Production of biodiesel from the resources endogeneous of Timor Leste

Os biocombustíveis têm estado na linha da frente das políticas energéticas mundiais visto que as suas vantagens conseguem colmatar as incertezas e resolver alguns dos problemas associados aos combustíveis fósseis. O biodiesel tem provado ser um combustível muito fiável, alternativo ao petrodiesel. É uma mistura de ésteres alquílicos produzidos a partir de óleos vegetais e gorduras animais através de uma reacção de transesterificação. Como combustível, o biodiesel é economicamente viável, socialmente responsável, tecnicamente compatível e ambientalmente amigável. O principal desafio associado ao seu desenvolvimento tem a ver com a escolha de matéria-prima para a sua produção. Nos países do terceiro mundo, óleos alimentares são mais importantes para alimentar pessoas do que fazer funcionar carros. Esta tese tem como objectivos produzir/processar biodiesel a partir de recursos endógenos de Timor-Leste e medir/prever as propriedades termodinâmicas do biodiesel, a partir das dos esteres alquílicos. A síntese do biodiesel a partir dos óleos de Aleurites moluccana, Jatropha curcas e borras de café foram aqui estudados. As propriedades termodinâmicas como densidade, viscosidade, tensão superficial, volatilidade e velocidade do som também foram medidas e estimadas usando modelos preditivos disponíveis na literatura, incluindo as equações de estado CPA e soft-SAFT. Timor-Leste é um país muito rico em recursos naturais, mas a maioria da população ainda vive na pobreza e na privação de acesso a serviços básicos e condições de vida decentes. A exploração de petróleo e gás no mar de Timor tem sido controlado pelo Fundo Petrolífero. O país ainda carece de electricidade e combustíveis que são cruciais para materializar as políticas de redução da pobreza. Como solução, o governo timorense criou recentemente o Plano Estratégico de Desenvolvimento a 20 anos cujas prioridades incluem trazer o desenvolvimento do petróleo do mar para a costa sul de Timor-Leste e desenvolver as energias renováveis. É neste último contexto que o biodiesel se insere. O seu desenvolvimento no país poderá ser uma solução para o fornecimento de electricidade, a criação de empregos e sobretudo o combate contra a pobreza e a privação. Para ser usado como combustível, no entanto, o biodiesel deve possuir propriedades termodinâmicas coerentes com as especificadas nas normas da ASTM D6751 (nos Estados Unidos) ou EN 14214 (na Europa) para garantir uma adequada ignição, atomização e combustão do biodiesel no motor.

Determinação da qualidade do fruto em citrinos de diferentes modos de produção

Dissertação mest., Agricultura Sustentável, Universidade do Algarve, 2007

Human factors required for mycobacterium tuberculosis macrophage infection

Tese de doutoramento, Farmácia (Biologia Celular e Molecular), Universidade de Lisboa, Faculdade de Farmácia, 2014

How does developmental plasticity differ between diverse types of nutrition regimes?

Tese de mestrado em Biologia Evolutiva e do Desenvolvimento, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016

Lyophilisation of influenza, rabies and Marburg lentiviral pseudotype viruses for the development and distribution of a neutralisation-assay based diagnostic kit

Pseudotype viruses (PVs) are chimeric, replication-deficient virions that mimic wild-type virus entry mechanisms and can be safely employed in neutralisation assays, bypassing the need for high biosafety requirements and performing comparably to established serological assays. However, PV supernatant necessitates -80°C long-term storage and cold-chain maintenance during transport, which limits the scope of dissemination and application throughout resource-limited laboratories. We therefore investigated the effects of lyophilisation on influenza, rabies and Marburg PV stability, with a view to developing a pseudotype virus neutralisation assay (PVNA) based kit suitable for affordable global distribution. Infectivity of each PV was calculated after lyophilisation and immediate reconstitution, as well as subsequent to incubation of freeze-dried pellets at varying temperatures, humidities and timepoints. Integrity of glycoprotein structure following treatment was also assessed by employing lyophilised PVs in downstream PVNAs. In the presence of 0.5M sucrose-PBS cryoprotectant, each freeze-dried pseudotype was stably stored for 4 weeks at up to 37°C and could be neutralised to the same potency as unlyophilised PVs when employed in PVNAs. These results confirm the viability of a freeze-dried PVNA-based kit, which could significantly facilitate low-cost serology for a wide portfolio of emerging infectious viruses.

Intake of dairy products in relation to periodontitis in older Danish adults

This cross-sectional study investigates whether calcium intakes from dairy and non-dairy sources, and absolute intakes of various dairy products, are associated with periodontitis. The calcium intake (mg/day) of 135 older Danish adults was estimated by a diet history interview and divided into dairy and non-dairy calcium. Dairy food intake (g/day) was classified into four groups: milk, cheese, fermented foods and other foods. Periodontitis was defined as the number of teeth with attachment loss ≥3 mm. Intakes of total dairy calcium (Incidence-rate ratio (IRR) = 0.97; p = 0.021), calcium from milk (IRR = 0.97; p = 0.025) and fermented foods (IRR = 0.96; p = 0.03) were inversely and significantly associated with periodontitis after adjustment for age, gender, education, sucrose intake, alcohol consumption, smoking, physical activity, vitamin D intake, heart disease, visits to the dentist, use of dental floss and bleeding on probing, but non-dairy calcium, calcium from cheese and other types of dairy food intakes were not. Total dairy foods (IRR = 0.96; p = 0.003), milk (IRR = 0.96; p = 0.028) and fermented foods intakes (IRR = 0.97; p = 0.029) were associated with reduced risk of periodontitis, but cheese and other dairy foods intakes were not. These results suggest that dairy calcium, particularly from milk and fermented products, may protect against periodontitis. Prospective studies are required to confirm these findings.

Calcium, vitamin D, casein and whey protein intakes and periodontitis among Danish adults

Objective: To investigate whether intakes of Ca, vitamin D, casein and whey are associated with periodontitis and to investigate the possibility of interactions between them. Design: Cross-sectional study. An Internet-based, 267-item FFQ was used to assess dietary intake. Intakes of casein (32·0 g/d), whey proteins (9·6 g/d) and vitamin D (5·8 μg/d) were classified as within v. above the 50th percentile. Ca intake was classified as within v. below age-specific recommendations. Severe periodontitis was defined as having ≥2 inter-proximal sites with clinical attachment loss ≥6 mm (not on the same tooth) and ≥1 inter-proximal site with pocket depth ≥5 mm. Since vitamin D influences Ca absorption, models were stratified by lower and higher (<5·8 v. ≥5·8 µg/d) vitamin D intake. Setting Danish Health Examination Survey (DANHES) 2007–2008. Subjects Adult participants (n 3287) in the oral health study of DANHES 2007–2008. Results Intakes of Ca within recommendations (OR=0·76; 95 % CI 0·58, 0·99), whey ≥9·6 g/d (OR=0·75; 95 % CI 0·58, 0·97) and casein ≥32 g/d (OR=0·75 95 % CI 0·58, 0·97) were associated with lower likelihood of severe periodontitis after adjustment for age, gender, education, smoking, sucrose intake, alcohol consumption, number of teeth, daily brushing, regular visits to the dentist and chronic illness, irrespective of vitamin D intake levels. Intake of vitamin D alone was not associated severe with periodontitis. Conclusions Intakes of Ca, casein and whey protein were inversely associated with periodontitis. Consumption of foods rich in Ca, casein and whey (e.g. dairy foods) should be promoted, as they may contribute to the prevention of periodontitis. Further longitudinal studies are required to confirm these associations.

Calcium, vitamin D, casein and whey protein intakes and periodontitis among Danish adults

OBJECTIVE: To investigate whether intakes of Ca, vitamin D, casein and whey are associated with periodontitis and to investigate the possibility of interactions between them. DESIGN: Cross-sectional study. An Internet-based, 267-item FFQ was used to assess dietary intake. Intakes of casein (32.0 g/d), whey proteins (9.6 g/d) and vitamin D (5.8 mug/d) were classified as within v. above the 50th percentile. Ca intake was classified as within v. below age-specific recommendations. Severe periodontitis was defined as having >/=2 inter-proximal sites with clinical attachment loss >/=6 mm (not on the same tooth) and >/=1 inter-proximal site with pocket depth >/=5 mm. Since vitamin D influences Ca absorption, models were stratified by lower and higher (<5.8 v. >/=5.8 microg/d) vitamin D intake. SETTING: Danish Health Examination Survey (DANHES) 2007-2008. SUBJECTS: Adult participants (n 3287) in the oral health study of DANHES 2007-2008. RESULTS: Intakes of Ca within recommendations (OR=0.76; 95 % CI 0.58, 0.99), whey >/=9.6 g/d (OR=0.75; 95 % CI 0.58, 0.97) and casein >/=32 g/d (OR=0.75 95 % CI 0.58, 0.97) were associated with lower likelihood of severe periodontitis after adjustment for age, gender, education, smoking, sucrose intake, alcohol consumption, number of teeth, daily brushing, regular visits to the dentist and chronic illness, irrespective of vitamin D intake levels. Intake of vitamin D alone was not associated severe with periodontitis. CONCLUSIONS: Intakes of Ca, casein and whey protein were inversely associated with periodontitis. Consumption of foods rich in Ca, casein and whey (e.g. dairy foods) should be promoted, as they may contribute to the prevention of periodontitis. Further longitudinal studies are required to confirm these associations.

Determination of tartaric acid in wines by FIA with tubular tartrate-selective electrodes

A flow injection analysis (FIA) system comprising a tartrate- (TAT) selective electrode has been developed for determination of tartaric acid in wines. Several electrodes constructed for this purpose had a PVC membrane with a complex of quaternary ammonium and TAT as anion exchanger, a phenol derivative as additive, and a more or less polar mediator solvent. Characterization of the electrodes showed behavior was best for membranes with o-nitrophenyl octyl ether as solvent. On injection of 500 μL into a phosphate buffer carrier (pH = 3.1; ionic strength 10–2 mol/L) flowing at 3 mL/min, the slope was 58.06 ± 0.6 with a lower limit of linear range of 5.0 × 10–4 mol/L TAT and R2 = 0.9989. The interference of several species, e.g. chloride, bromide, iodide, nitrate, gallic acid, tannin, sucrose, glucose, fructose, acetate, and citrate, was evaluated in terms of potentiometric selectivity coefficients. The Hofmeister series was followed for inorganic species and the most interfering organic ion was citrate. When red and white wines were analyzed and the results compared with those from an independent method they were found to be accurate, with relative standard deviations below 5.0%.

Citrate selective electrodes for the flow injection analysis of soft drinks, beers and pharmaceutical products

Aiming the establishment of simple and accurate readings of citric acid (CA) in complex samples, citrate (CIT) selective electrodes with tubular configuration and polymeric membranes plus a quaternary ammonium ion exchanger were constructed. Several selective membranes were prepared for this purpose, having distinct mediator solvents (with quite different polarities) and, in some cases, p-tert-octylphenol (TOP) as additive. The latter was used regarding a possible increase in selectivity. The general working characteristics of all prepared electrodes were evaluated in a low dispersion flow injection analysis (FIA) manifold by injecting 500µl of citrate standard solutions into an ionic strength (IS) adjuster carrier (10−2 mol l−1) flowing at 3ml min−1. Good potentiometric response, with an average slope and a repeatability of 61.9mV per decade and ±0.8%, respectively, resulted from selective membranes comprising additive and bis(2-ethylhexyl)sebacate (bEHS) as mediator solvent. The same membranes conducted as well to the best selectivity characteristics, assessed by the separated solutions method and for several chemical species, such as chloride, nitrate, ascorbate, glucose, fructose and sucrose. Pharmaceutical preparations, soft drinks and beers were analyzed under conditions that enabled simultaneous pH and ionic strength adjustment (pH = 3.2; ionic strength = 10−2 mol l−1), and the attained results agreed well with the used reference method (relative error < 4%). The above experimental conditions promoted a significant increase in sensitivity of the potentiometric response, with a supra-Nernstian slope of 80.2mV per decade, and allowed the analysis of about 90 samples per hour, with a relative standard deviation <1.0%.

Construction and evaluation of cysteine selective electrodes for FIA analysis of pharmaceuticals

A flow injection analysis (FIA) system comprising a cysteine selective electrode as detection system was developed for determination of this amino acid in pharmaceuticals. Several electrodes were constructed for this purpose, having PVC membranes with different ionic exchangers and mediator solvents. Better working characteristics were attained with membranes comprising o-nitrophenyl octyl ether as mediator solvent and a tetraphenylborate based ionic-sensor. Injection of 500 µL standard solutions into an ionic strength adjuster carrier (3x10-3 M) of barium chloride flowing at 2.4mL min-1, showed linearity ranges from 5.0x10-5 to 5.0x10-3 M, with slopes of 76.4±0.6mV decade-1 and R2>0.9935. Slope decreased significantly under the requirement of a pH adjustment, selected at 4.5. Interference of several compounds (sodium, potassium, magnesium, barium, glucose, fructose, and sucrose) was estimated by potentiometric selectivity coefficients and considered negligible. Analysis of real samples were performed and considered accurate, with a relative error to an independent method of +2.7%.

Ciprofloxacin-imprinted polymeric receptors as ionophores for potentiometric transduction

A 3D-mirror synthetic receptor for ciprofloxacin host–guest interactions and potentiometric transduction is presented. The host cavity was shaped on a polymeric surface assembled with methacrylic acid or 2-vinyl pyridine monomers by radical polymerization. Molecularly imprinted particles were dispersed in 2-nitrophenyl octyl ether and entrapped in a poly(vinyl chloride) matrix. The sensors exhibited a near-Nernstian response in steady state evaluations. Slopes and detection limits ranged from 26.8 to 50.0mVdecade−1 and 1.0×10−5 to 2.7×10−5 mol L−1, respectively. Good selectivity was observed for trimethoprim, enrofloxacin, tetracycline, cysteine, galactose, hydroxylamine, creatinine, ammonium chloride, sucrose, glucose, sulphamerazine and sulfadiazine. The sensors were successfully applied to the determination of ciprofloxacin concentrations in fish and in pharmaceuticals. The method presented offered the advantages of simplicity, accuracy, applicability to colored and turbid samples and automation feasibility, as well as confirming the use of molecularly imprinted polymers as ionophores for organic ion recognition in potentiometric transduction.

Artificial antibodies for troponin T by its imprinting on the surface of multiwalled carbon nanotubes: Its use as sensory surfaces

A novel artificial antibody for troponin T (TnT) was synthesized by molecular imprint (MI) on the surface of multiwalled carbon nanotubes (MWCNT). This was done by attaching TnT to the MWCNT surface, and filling the vacant spaces by polymerizing under mild conditions acrylamide (monomer) in N,N′-methylenebisacrylamide (cross-linker) and ammonium persulphate (initiator). After removing the template, the obtained biomaterial was able to rebind TnT and discriminate it among other interfering species. Stereochemical recognition of TnT was confirmed by the non-rebinding ability displayed by non-imprinted (NI) materials, obtained by imprinting without a template. SEM and FTIR analysis confirmed the surface modification of the MWCNT. The ability of this biomaterial to rebind TnT was confirmed by including it as electroactive compound in a PVC/plasticizer mixture coating a wire of silver, gold or titanium. Anionic slopes of 50 mV decade−1 were obtained for the gold wire coated with MI-based membranes dipped in HEPES buffer of pH 7. The limit of detection was 0.16 μg mL−1. Neither the NI-MWCNT nor the MWCNT showed the ability to recognize the template. Good selectivity was observed against creatinine, sucrose, fructose, myoglobin, sodium glutamate, thiamine and urea. The sensor was tested successfully on serum samples. It is expected that this work opens new horizons on the design of new artificial antibodies for complex protein structures.

Ciprofloxacin-imprinted polymeric receptors as ionophores for potentiometric transduction

A 3D-mirror synthetic receptor for ciprofloxacin host–guest interactions and potentiometric transduction is presented. The host cavity was shaped on a polymeric surface assembled with methacrylic acid or 2-vinyl pyridine monomers by radical polymerization. Molecularly imprinted particles were dispersed in 2-nitrophenyl octyl ether and entrapped in a poly(vinyl chloride) matrix. The sensors exhibited a near-Nernstian response in steady state evaluations. Slopes and detection limits ranged from 26.8 to 50.0 mV decade−1 and 1.0 × 10−5 to 2.7 × 10−5 mol L−1, respectively. Good selectivity was observed for trimethoprim, enrofloxacin, tetracycline, cysteine, galactose, hydroxylamine, creatinine, ammonium chloride, sucrose, glucose, sulphamerazine and sulfadiazine. The sensors were successfully applied to the determination of ciprofloxacin concentrations in fish and in pharmaceuticals. The method presented offered the advantages of simplicity, accuracy, applicability to colored and turbid samples and automation feasibility, as well as confirming the use of molecularly imprinted polymers as ionophores for organic ion recognition in potentiometric transduction.

Valorização da Borra de Café: Otimização da Produção de Biodiesel por Catálise Enzimática

O decréscimo das reservas de petróleo e as consequências ambientais resultantes do recurso a combustíveis fósseis nos motores a diesel têm levado à procura de combustíveis alternativos. Esta pesquisa alicerçada nas fontes de energia renovável tornou-se essencial, face à crescente procura de energia e ao limitado fornecimento de combustíveis fósseis . Resíduos de óleo de cozinha, gordura animal, entre outros resíduos de origem biológica, tais como a borra de café, são exemplos de matérias-primas para a produção de biodiesel. A sua valorização tem interesse quer pela perspetiva ambiental, quer pela económica, pois aumenta não só a flexibilidade e diversificação das matérias-primas, mas também contribui para uma estabilidade de custos e alteração nas políticas agrícolas e de uso do solo. É neste contexto que se enquadra o biodiesel e a borra de café, pretendendo-se aqui efetuar o estudo da produção, à escala laboratorial, de biodiesel a partir da borra de café, por transesterificação enzimática, visando a procura das melhores condições reacionais. Iniciando-se com a caracterização da borra de café, foram avaliados antes e após a extração do óleo da borra de café, diversos parâmetros, de entre os quais se destacam: o teor de humidade (16,97% e 6,79%), teor de cinzas (1,91 e 1,57%), teor de azoto (1,71 e 2,30%), teor de proteínas (10,7 e 14,4%), teor de carbono (70,2 e 71,7%), teor de celulose bruta (14,77 e 18,48%), teor de lenhina (31,03% e 30,97%) e poder calorifico superior (19,5 MJ/kg e 19,9 MJ/kg). Sumariamente, constatou-se que os valores da maioria dos parâmetros não difere substancialmente dos valores encontrados na literatura, tendo sido evidenciado o potencial da utilização desta biomassa, como fonte calorifica para queima e geração de energia. Sendo a caracterização do óleo extraído da borra de café um dos objetivos antecedentes à produção do biodiesel, pretendeu-se avaliar os diferentes parâmetros mais significativos. No que diz respeito à caracterização do óleo extraído, distingue-se a sua viscosidade cinemática (38,04 mm2/s), densidade 0,9032 g/cm3, poder calorífico de 37,9 kcal/kg, índice de iodo igual a 63,0 gI2/ 100 g óleo, o teor de água do óleo foi de 0,15 %, o índice de acidez igual a 44,8 mg KOH/g óleo, ponto de inflamação superior a 120 ºC e teor em ácidos gordos de 82,8%. Inicialmente foram efetuados ensaios preliminares, a fim de selecionar a lipase (Lipase RMIM, TL 100L e CALB L) e álcool (metanol ou etanol puros) mais adequados à produção de biodiesel, pelo que o rendimento de 83,5% foi obtido através da transesterificação mediada pela lipase RMIM, utilizando como álcool o etanol. Sendo outro dos objetivos a otimização do processo de transesterificação enzimática, através de um desenho composto central a três variáveis (razão molar etanol: óleo, concentração de enzima e temperatura), recorrendo ao software JMP 8.0, determinou-se como melhores condições, uma razão molar etanol: óleo 5:1, adição de 4,5% (m/m) de enzima e uma temperatura de 45 ºC, que conduziram a um rendimento experimental equivalente a 96,7 % e teor de ésteres 87,6%. Nestas condições, o rendimento teórico foi de 99,98%. Procurou-se ainda estudar o efeito da adição de água ao etanol, isto é, o efeito da variação da concentração do etanol pela adição de água, para teores de etanol de 92%, 85% e 75%. Verificou-se que até 92% decorreu um aumento da transesterificação (97,2%) para um teor de ésteres de (92,2%), pelo que para teores superiores de água adicionada (75% e 85%) ocorreu um decréscimo no teor final em ésteres (77,2% e 89,9%) e no rendimento da reação (84,3% e 91,9%). Isto indica a ocorrência da reação de hidrólise em maior extensão, que leva ao desvio do equilíbrio no sentido contrário à reação de formação dos produtos, isto é, dos ésteres. Finalmente, relativamente aos custos associados ao processo de produção de biodiesel, foram estimados para o conjunto de 27 ensaios realizados neste trabalho, e que corresponderam a 767,4 g de biodiesel produzido, sendo o custo dos reagentes superior ao custo energético, de 156,16 € e 126,02 €, respetivamente. Naturalmente que não esperamos que, a nível industrial os custos sejam desta ordem de grandeza, tanto mais que há economia de escala e que as enzimas utilizadas no processo deveriam ser reutilizadas diversas vezes.