Cimentos injetáveis à base de fosfatos de cálcio para vertebroplastia

O principal objectivo desta investigação foi o desenvolvimento cimentos de fosfatos de cálcio com injetabilidade melhorada e propriedades mecânicas adequadas para aplicação em vertebroplastia. Os pós de fosfato de tricálcico (TCP) não dopados e dopados (Mg, Sr e Mn) usados neste estudo foram obtidos pelo processo de precipitação em meio aquoso, seguidos de tratamento térmico de forma a obter as fases pretendidas, α− e β−TCP. A substituição parcial de iões Ca por iões dopantes mostrou ter implicações em termos de estabilidade térmica da fase β−TCP. Os resultados demonstraram que as transformações de fase alotrópicas β↔α−TCP são fortemente influenciadas por variáveis experimentais como a taxa de arrefecimento, a presença de impurezas de pirofosfato de cálcio e a extensão do grau de dopagem com Mg. Os cimentos foram preparados através da mistura de pós, β−TCP (não dopados e dopados) e fosfato monocálcico monidratado (MCPM), com meios líquidos diferentes usando ácido cítrico e açucares (sucrose e frutose) como agentes retardadores de presa, e o polietilenoglicol, a hidroxipropilmetilcelulose e a polivinilpirrolidona como agentes gelificantes. Estes aditivos, principalmente o ácido cítrico, e o MCPM aumentam significativamente a força iónica do meio, influenciando a injetabilidade das pastas. Os resultados também mostraram que a distribuição de tamanho de partícula dos pós é um factor determinante na injetabilidade das pastas cimentícias. A combinação da co-dopagem de Mn e Sr com a adição de sucrose no líquido de presa e com uma distribuição de tamanho de partícula dos pós adequada resultou em cimentos de brushite com propriedades bastante melhoradas em termos de manuseamento, microestrutura, comportamento mecânico e biológico: (i) o tempo inicial de presa passou de ~3 min to ~9 min; (ii) as pastas cimentícias foram totalmente injectadas para uma razão liquido/pó de 0.28 mL g−1 com ausência do efeito de “filter-pressing��� (separação de fases líquida e sólida); (iii) após imersão numa solução durante 48 h, as amostras de cimento molhadas apresentam uma porosidade total de ~32% e uma resistência a compressão de ~17 MPa, valor muito superior ao obtido para os cimentos sem açúcar não dopados (5 MPa) ou dopados só com Sr (10 MPa); e (iv) o desempenho biológico, incluindo a adesão e crescimento de células osteoblásticas na superfície do cimento, foi muito melhorado. Este conjunto de propriedades torna os cimentos excelentes para regeneração óssea e engenharia de tecidos, e muito promissores para aplicação em vertebroplastia.

Caracterização da fração de óleo de café extraido de grãos sadios, verdes e preto-verdes, e a influência na adição deste na sensorial de café liofilizado

The application of roasted coffee oil directly on freeze dried soluble coffee is used to minimize the formation of fine poder which adhere on the glass packaging, which results in a negative visual appearance, as well as contributes to the aromatic impact when opening the packaging. The coffee oil is considered a high cost product obtained from Arabica coffee beans, previosly selected and roasted, by mechanical press. In Brazil the coffee culture and marketing results in the selection of the beans by type of defects and beverage, the volume of exportation works with types of coffee beans with low quantity of defects resulting in a large volume of defective coffee beans trading on the domestic market. Nevertheless, coffees which present defective grains like green, black-green beans present differences in the final flavor of the roasted coffees. The aim of this study was to evaluate the chemical composition of the oils extracted from grains classified as normal, green and black-green, at natural and roasted conditions. The oil was obtained by cold extraction using solvents of different polarities, and yield was calculated as well as its fatty acid composition. The oil of the roasted defective coffee grains was also used to prepare drinks of lyophilized soluble coffee in order to verify if jugdes were able to differenciate the sensory caracteristics of the beverages, in comparison to the product prepared using commercial oil obtained by mechanical pressing. Samples of oil obtained from defective grains showed similar extraction yields compared to hot extraction. Cromatographs of oils of the deffective grains did not showed differences compared to normal grains. In relation to the sensory analysis of the soluble coffee beverages, it was verified that when applying oils of light roasted black-green beans or oils of medium and dark roasted green beans obtained with rapid process, judges had more difficulties to distinguish differences between samples. Economic viability demonstrated that with the actual prices of the coffee beans, the use of defective beans could reduce in 64% the costs of the raw beans.

A construção do professor generalista enquanto afirmação plena da profissionalidade docente

Relatório de estágio apresentado à Escola Superior de Educação de Paula Frassinetti para a obtenção do grau de Mestre em Ensino do 1.º e 2.º Ciclo do Ensino Básico

Suomen turvallisuuspoliittisen ratkaisun lähtökohtia

Suomi luopui puolueettomuuspolitiikasta turvallisuuspoliittisena linjanaan kun se liittyi Euroopan unioniin ennen kaikkea turvallisuussyistä. Vaikka Suomi on EU-jäsenyyden myötä poliittisesti liittoutunut ja vaikka se on jatkuvasti laajentanut ja syventänyt yhteistyötään NATOn kanssa, Suomi on yhä sotilaallisesti liittoutumaton valtio. Suomen turvallisuuspoliittinen toimintaympäristö on ollut poikkeuksellisen vakaa kylmän sodan jälkeen ennen kaikkea siksi, että maailman voimakkain suurvalta Yhdysvallat on yhä sotilaallisesti läsnä Euroopassa ja Euroopan integraatio on jatkunut ja syventynyt. Suomi on sitonut nykyisen turvallisuuspoliittisen linjansa turvallisuusympäristönsä pysyvyyteen. Viime vuosina NATOn laajentuminen entisen Neuvostoliiton alueelle on voimistanut läntisten suurvaltojen ja Venäjän välistä valtakamppailua ja turvallisuuskilpailua Suomen lähialueella. Viimeistään Ukrainan konflikti on tehnyt ajankohtaiseksi myös kysymyksen Suomen sotilaallisesta liittoutumisesta. Tässä artikkeliteoksessa turvallisuuspolitiikan asiantuntijat analysoivat keskeisimpien ulkoisten toimijoiden – EU:n, Ruotsin, Viron, Venäjän, Yhdysvaltojen ja NATOn – merkitystä Suomen turvallisuuspoliittisen toimintaympäristön vakaudelle ja Suomen turvallisuudelle sekä pohtivat, onko Suomen syytä muuttaa nykyistä turvallisuuspoliittista linjaansa turvallisuusympäristössä tapahtuneiden muutosten vuoksi. Kirjoittajat myös arvioivat Suomen mahdolliseen sotilaalliseen liittoutumiseen liittyviä etuja ja haittoja verrattuna nykyiseen turvallisuuspoliittiseen ratkaisuun. Teoksen kirjoittajien toisistaan poikkeavat näkemykset Suomen turvallisuuspoliittisen toimintaympäristön vakaudesta, NATOn laajentumisen vaikutuksista Itämeren alueella, Venäjän valtapolitiikasta ja sen Suomelle muodostaman sotilaallisen uhan voimakkuudesta, NATOn pelotteen uskottavuudesta ja Yhdysvaltojen sitoutumisesta liittolaistensa puolustamiseen sekä Suomen NATO-jäsenyyden eduista ja haitoista valaisevat laajasti kysymystä Suomen turvallisuudesta ja turvallisuuspoliittisesta ratkaisusta. Suomelle sen geopoliittinen asema Venäjälle strategisesti elintärkeiden Kuolan alueen ja Pietari–Moskova-ydinalueen välittömässä läheisyydessä on ongelmallinen maan turvallisuuden kannalta. Suurvalta Venäjä onkin edelleen keskeisin Suomen turvallisuuteen ja turvallisuuspoliittiseen ratkaisuun vaikuttava ulkoinen toimija. Neuvostoliiton hajoamisen jälkeen Suomella on ollut ainutlaatuinen mahdollisuus liittoutua Yhdysvaltojen kanssa NATO-jäsenyyden myötä Venäjän potentiaalista sotilaallista uhkaa vastaan. Toisaalta Suomella ei kuitenkaan ole ollut pakottavaa tarvetta siihen, koska se on välillisesti hyötynyt Yhdysvaltojen suurstrategiasta Euroopassa ja koska Venäjän valtapolitiikka on kohdistunut ennen kaikkea entisen Neuvostoliiton alueelle. Vaikka Ukrainan konflikti onkin lisännyt poliittista ja sotilaallista jännitettä Itämeren alueella, tämän teoksen perusteella on kuitenkin mahdotonta antaa yksiselitteistä vastausta siihen, pitäisikö Suomen sen turvallisuuspoliittisessa toimintaympäristössä tapahtuneen muutoksen seurauksena liittyä NATOn jäseneksi vai ei. Halutessaan Suomi voi siis edelleen jatkaa nykyisellä turvallisuuspoliittisella linjallaan sotilaallisesti liittoutumattomana valtiona, mutta samalla sen täytyy kuitenkin pitää myös sotilaallinen liittoutuminen avoimena turvallisuuspoliittisena vaihtoehtona tulevaisuudessa.

Studies on the synthesis of novel PP2A inhibitors and a GPCR detergent

Chapter 1 While targeting kinases in oncology research has been explored extensively, targeting protein phosphatases is currently in its infancy. However, a number of pharmaceutical companies are currently looking to expand their research efforts in this area. PP2A has been shown to down-regulate ERK5, a mitogen-activated protein kinase (MAPK) that has been shown to be important in driving the invasive phenotype of prostate cancer. Fostriecin and its related structural analogues PD 113,270 and 113,271 have been shown to inhibit a mitotic entry checkpoint in cell growth through the potent and selective inhibition of protein phosphatases PP1, PP2A, and PP4 (IC50 of 45 μM, 1.5 nM, and 3 nM respectively). Fostriecin is one of the most selective protein phosphatase inhibitors disclosed to date with a 104 fold selectivity for PP2A/PP4 versus PP1. Unfortunately, fostriecin and its analogues are very unstable, and this instability has effectively prevented them from being used as effective therapeutic leads. The microcystins and nodularins on the other hand, exhibit significant inhibitory activity against PP1 and PP2A (IC50 = 26 pM and 1.8 nM respectively), but their high toxicity has prevented any therapeutic application. Truncation of the ADDA chain from these polypeptides completely attenuates PP inhibitory activity. Simpler analogues incorporating the N-acylated ADDA chain and D-Ala retain moderate activity against PP1 and PP2A (IC50 = 1.0 μM and 0.17 μM respectively). The generation of a new series of fostriecin analogues to further expand its structure-activity relationship is envisaged with a view to creating new more stable PP2A inhibitors. It was hoped that by incorporating some of the more stable structural features of ADDA into fostriecin that stability and activity could be reconciled. With that in mind a series of PP2A inhibitors were synthesised and biologically evaluated. Chapter 2 GPCRs are an important area of research and are the targets of a quarter of the drugs on the market (2005). As a result, GPCRs continue to be at the forefront of research in both small and large drug companies. However one of the difficulties in studying this diverse class of membrane proteins is their tendency to denature in aqueous solution. As a result there is a pressing need to develop new detergents to solubilise, stabilise and crystallise GPCRs in their native form for further study. Cholesterol analogues have been shown to be important for stabilising membrane proteins and preventing their thermal inactivation. In addition the β2-adrenergic receptor, a GPCR membrane protein, has been crystallised in the active state with two cholesterol molecules bound between the I, II, III and IV helices of the protein. This appears to represent a distinct cholesterol binding pocket on the membrane protein that is speculated to be conserved across up to 44% of the rhodopsin class of GPCRs. CHOBIMALT is a cholesterol-based detergent that has been shown to exhibit promising GPCR-stabilising properties. When benchmarked against other cholesterol based detergents it was found to be superior to all others tested except for cholesteryl hemisuccinate.1 CHOBIMALT has an aggregation number of roughly 200 and forms 210 ± 30 kDa micelles, which are significantly larger than those of most detergents used for biological systems which is likely due to the packing constraints associated with CHOBMALT’s large polar headgroup.2 As a result, CHOBIMALT is used mostly as an additive to other commercially available detergents in order to decrease micelle size. A branched dimaltoside motif is common in recently synthesised detergents by Chae and co-workers. These detergents have shown promising detergent properties, for example the maltose neopentyl glycol (MNG) detergent synthesised by Chae. This branched dimaltoside detergent was shown to be able to solubilise and stabilise the very labile light harvesting complex I (LHI) from Rhodopsin capsulatus in its active form for 20 days with little loss of protein conformation.3 A cholesterol-based detergent was envisaged that combines the cholesterol framework of CHOBIMALT but replaces its linear tetrasaccharide with a branched dimaltoside. This detergent would then be investigated to assess its ability to solubilise, stabilise and crystallise GPCR proteins. This cholesterol-based detergent (shown below) was eventually synthesised in 9 linear steps from cholesterol.

Multiraciality Enters the University: Mixed Race Identity and Knowledge Production in Higher Education

“Multiraciality Enters the University: Mixed Race Identity and Knowledge Production in Higher Education,” explores how the category of “mixed race” has underpinned university politics in California, through student organizing, admissions debates, and the development of a new field of study. By treating the concept of privatization as central to both multiraciality and the neoliberal university, this project asks how and in what capacity has the discourses of multiracialism and the growing recognition of mixed race student populations shaped administrative, social, and academic debates at the state’s flagship universities—the University of California at Berkeley and Los Angeles. This project argues that the mixed race population symbolizing so-called “post-racial societies” is fundamentally attached to the concept of self-authorship, which can work to challenge the rights and resources for college students of color. Through a close reading of texts, including archival materials, policy and media debates, and interviews, I assert that the contemporary deployment of mixed race within the US academy represents a particularly post-civil rights development, undergirded by a genealogy of U.S. liberal individualism. This project ultimately reveals the pressing need to rethink ways to disrupt institutionalized racism in the new millennium.

Sedimentary evidence for a mid-Holocene iceberg-generated tsunami in a coastal lake, west Greenland

We report sedimentological evidence for a tsunami from a coastal lake at Innaarsuit, Disko Bugt (west Greenland), which was most likely generated by a rolling iceberg. The tsunami invaded the lake c. 6000 years ago, during a period of time when relative sea level (RSL) was falling quickly because of isostatic rebound. We use the background rate of RSL fall, together with an age model for the sediment sequence, to infer a minimum wave run-up during the event of c. 3.3 m. The stratigraphic signature of the event bears similarities to that described from studies of the early-Holocene Storegga slide tsunami in Norwegian coastal basins. Conditions conducive to iceberg tsunami include a supply of icebergs, deep water close to the shore, a depositional setting protected from storms or landslide tsunami, and a coastal configuration that has the potential to amplify the height of tsunami waves as water depths shallow and the waves approach and impact the coast. Future warming of polar regions will lead to increased calving and iceberg production, at a time when human use of polar coasts will also grow. We predict, therefore, that iceberg-generated tsunami will become a growing hazard in polar coastal waters, especially in areas adjacent to large, fast-flowing, marine-terminating ice streams that are close to human populations or infrastructure.

Post-rift evolution of the Gulf of Lion margin tested by stratigraphic modelling

The sedimentary architecture of basins and passive margins is determined by a complex interaction of parameters, including subsidence, eustasy, and sediment supply. A quantification of the post-rift (20 Ma-0 Ma) vertical movements of the Gulf of Lion (West Mediterranean) is proposed here based on the stratigraphic study of sedimentary paleomarkers using a large 3D grid of reflection seismic data, correlations with existing drillings, and refraction data. Post-rift subsidence was measured by the direct use of sedimentary geometries analysed in 3D and validated by numerical stratigraphic modelling. Three domains of subsidence were found: on the continental shelf and slope, subsidence corresponds to a seaward tilting with different amplitudes, whereas the deep basin subsides purely vertically. We show that these domains fit with the deeper crustal domains highlighted by previous geophysical data, and that post-break-up subsidence follows the initial hinge lines of the rifting phase. Subsidence rates are quantified on each domain for each stratigraphic interval. At a constant distance from the rotational hinge line, the Plio-Quaternary subsidence rate is constant on the shelf overall. Conversely, Miocene subsidence rates are very different on the eastern and western shelves. Stratigraphic simulations focused on the Messinian salinity crisis (MSC) were also performed. Their results are discussed together with our post-rift subsidence estimates in order to provide ideas and hypotheses for future detailed quantifications of Miocene subsidence, including isostatic readjustments linked to the MSC.

Close encounters: international exhibitions and the material culture of the British Empire, c.1880-1940

Apparitions of empire and imperial ideologies were deeply embedded in the International Exhibition, a distinct exhibitionary paradigm that came to prominence in the mid-nineteenth century. Exhibitions were platforms for the display of objects, the movement of people, and the dissemination of ideas across and between regions of the British Empire, thereby facilitating contact between its different cultures and societies. This thesis aims to disrupt a dominant understanding of International Exhibitions, which forwards the notion that all exhibitions, irrespective of when or where they were staged, upheld a singular imperial discourse (i.e. Greenhalgh 1988, Rydell 1984). Rather, this thesis suggests International Exhibitions responded to and reflected the unique social, political and economic circumstances in which they took place, functioning as cultural environments in which pressing concerns of the day were worked through. Understood thus, the International Exhibition becomes a space for self-presentation, serving as a stage from which a multitude of interests and identities were constructed, performed and projected. This thesis looks to the visual and material culture of the International Exhibition in order to uncover this more nuanced history, and foregrounds an analysis of the intersections between practices of exhibition-making and identity-making. The primary focus is a set of exhibitions held in Glasgow in the late-1880s and early-1900s, which extends the geographic and temporal boundaries of the existing scholarship. What is more, it looks at representations of Canada at these events, another party whose involvement in the International Exhibition tradition has gone largely unnoticed. Consequently, this thesis is a thematic investigation of the links between a municipality routinely deemed the ‘Second City of the Empire’ and a Dominion settler colony, two types of geographic setting rarely brought into dialogue. It analyses three key elements of the exhibition-making process, exploring how iconographies of ‘quasi-nationhood’ were expressed through an exhibition’s planning and negotiation, its architecture and its displays. This original research framework deliberately cuts across strata that continue to define conceptions of the British Empire, and pushes beyond a conceptual model defined by metropole and colony. Through examining International Exhibitions held in Glasgow in the late-Victorian and Edwardian periods, and visions of Canada in evidence at these events, the goal is to offer a novel intervention into the existing literature concerning the cultural history of empire, one that emphasises fluidity rather than fixity and which muddles the boundaries between centre and periphery.

Experiencia colombiana en reparación de núcleos de transformadores de potencia

Este artículo presenta el reporte de caso sobre fallas presentadas en el núcleo de transformadores de potencia y algunas experiencias técnicas y metodológicas en la reparación parcial y total de los mismos a varias unidades, hechas en Industrias Explorer Ingeniería S. A. S., empresa dedicada al mantenimiento y reparación de transformadores. También es presentada la metodología para la selección del tipo de lámina, sistema de corte, ensamble, ajuste y prensado del núcleo, ya que estas actividades son decisivas para conseguir un equipo con menores pérdidas y corrientes de vacío, así como menores niveles de ruido. Se describen las etapas para cálculo del flujo de operación del núcleo, circuito de prueba para la saturación del mismo, consideraciones para realizar la inspección termográfica y medición de las pérdidas de vacío, selección del tipo de lámina y técnicas de ensamble empleadas. Se presentan algunas experiencias como: cambio de medio núcleo, reaislamiento de zonas afectadas empleando fibras Nómex entre láminas, cambio total del núcleo por corte mal realizado desde fábrica, cambio total del núcleo por doble aterrizamiento que ocasionó calentamiento del mismo y afectó el aislamiento de sus láminas dejándolas en corto. En todos los casos se evidencia una disminución de las pérdidas de vacío. Finalmente se presentan el comportamiento de los transformadores después de ser puestos nuevamente en servicio.

Quantifying uplift and denudation of a thermally heterogeneous crust: a detailed multi-thermochronometeric study of central west Britain

Topography is often thought as exclusively linked to mountain ranges formed by plates collision. It is now, however, known that apart from compression, uplift and denudation of rocks may be triggered by rifting, like it happens at elevated passive margins, and away from plate boundaries by both intra-plate stress causing reactivation of older structures, and by epeirogenic movements driven by mantle dynamics and initiating long-wavelength uplift. In the Cenozoic, central west Britain and other parts of the North Atlantic margins experienced multiple episodes of rock uplift and denudation that have been variable both at spatial and temporal scales. The origin of topography in central west Britain is enigmatic, and because of its location, it may be related to any of the processes mentioned above. In this study, three low temperature thermochronometers, the apatite fission track (AFT) and apatite and zircon (U-Th-Sm)/He (AHe and ZHe, respectively) methods were used to establish the rock cooling history from 200◦C to 30◦C. The samples were collected from the intrusive rocks in the high elevation, high relief regions of the Lake District (NW England), southern Scotland and northern Wales. AFT ages from the region are youngest (55–70 Ma) in the Lake District and increase northwards into southern Scotland and southwards in north Wales (>200 Ma). AHe and ZHe ages show no systematic pattern; the former range from 50 to 80 Ma and the latter tend to record the post-emplacement cooling of the intrusions (200–400 Ma). The complex, multi-thermochronometric inverse modelling suggests a ubiquitous, rapid Late Cretaceous/early Palaeogene cooling event that is particularly marked in Lake District and Criffell. The timing and rate of cooling in southern Scotland and in northern Wales is poorly resolved as the amount of cooling was less than 60◦C. The Lake District plutons were at >110◦C prior to the early Palaeogene; cooling due to a combined effect of high heat flow, from the heat producing granite batholith, and the blanketing effect of the overlying low conductivity Late Mesozoic limestones and mudstones. Modelling of the heat transfer suggests that this combination produced an elevated geothermal gradient within the sedimentary rocks (50–70◦C/km) that was about two times higher than at the present day. Inverse modelling of the AFT and AHe data taking the crustal structure into consideration suggests that denudation was the highest, 2.0–2.5 km, in the coastal areas of the Lake District and southern Scotland, gradually decreasing to less than 1 km in the northern Southern Uplands and northern Wales. Both the rift-related uplift and the intra-plate compression poorly correlate with the timing, location and spatial distribution of the early Palaeogene denudation. The pattern of early Palaeogene denudation correlates with the thickness of magmatic underplating, if the changes of mean topography, Late Cretaceous water depth and eroded rock density are taken into consideration. However, the uplift due to underplating alone cannot fully justify the total early Palaeogene denudation. The amount that is not ex- plained by underplating is, however, roughly spatially constant across the study area and can be referred to the transient thermal uplift induced by the mantle plume arrival. No other mechanisms are required to explain the observed pattern of denudation. The onset of denudation across the region is not uniform. Denudation started at 70–75 Ma in the central part of the Lake District whereas the coastal areas the rapid erosion appears to have initiated later (65–60 Ma). This is ~10 Ma earlier than the first vol- canic manifestation of the proto-Iceland plume and favours the hypothesis of the short period of plume incubation below the lithosphere before the volcanism. In most of the localities, the rocks had cooled to temperatures lower than 30◦C by the end of the Palaeogene, suggesting that the total Neogene denudation was, at a maximum, several hundreds of metres. Rapid cooling in the last 3 million years is resolved in some places in southern Scotland, where it could be explained by glacial erosion and post-glacial isostatic uplift.

Ultra high pressure homogenization (UHPH) inactivation of Bacillus amyloliquefaciens spores in phosphate buffered saline (PBS) and milk

Ultra high pressure homogenization (UHPH) opens up new areas for dynamic high pressure assisted thermal sterilization of liquids. Bacillus amyloliquefaciens spores are resistant to high isostatic pressure and temperature and were suggested as potential surrogate for high pressure thermal sterilization validation. B. amyloliquefaciens spores suspended in PBS buffer (0.01 M, pH 7.0), low fat milk (1.5%, pH 6.7), and whole milk (3.5%, pH 6.7) at initial concentration of similar to 10(6) CFU/mL were subjected to UHPH treatments at 200, 300, and 350 MPa with an inlet temperature at similar to 80 degrees C. Thermal inactivation kinetics of B. amyloliquefaciens spores in PBS and milk were assessed with thin wall glass capillaries and modeled using first-order and Weibull models. The residence time during UHPH treatments was estimated to determine the contribution of temperature to spore inactivation by UHPH. No sublethal injury was detected after UHPH treatments using sodium chloride as selective component in the nutrient agar medium. The inactivation profiles of spores in PBS buffer and milk were compared and fat provided no clear protective effect for spores against treatments. Treatment at 200 MPa with valve temperatures lower than 125 degrees C caused no reduction of spores. A reduction of 3.5 log(10)CFU/mL of B. amyloliquefaciens spores was achieved by treatment at 350 MPa with a valve temperature higher than 150 degrees C. The modeled thermal inactivation and observed inactivation during UHPH treatments suggest that temperature could be the main lethal effect driving inactivation.

Síntese de carboidratos por microalgas e produção de bioetanol

A maior parte da energia hoje consumida no mundo é derivada de fontes como petróleo, carvão e gás natural. Essas fontes, no entanto, não são renováveis e podem se esgotar em data futura. Nas últimas décadas, as fontes renováveis de combustíveis de base biológica, em especial o bioetanol, têm sido consideradas como alternativa à matriz energética convencional. Porém, existe a necessidade de ampliação da oferta de matérias-primas para produção de etanol, sem pressionar a área plantada para produção de alimentos, o que tem levado empresas e países a investirem em pesquisas para maior utilização de outras matériasprimas. As microalgas surgem como uma das alternativas mais promissoras para a produção de bioetanol, sendo que modificações nas condições de cultivo podem propiciar incremento na concentração de carboidratos destas. Neste contexto, o objetivo deste trabalho foi avaliar a influência da concentração de nutrientes na concentração de carboidratos de microalgas e produzir bioetanol a partir destas. Avaliou-se a síntese de carboidratos das microalgas Chlorella homosphaera e Spirulina platensis LEB 52 em cultivos mixotróficos com diferentes concentrações do componente nitrogenado e cloreto de sódio adicionados aos meios de cultivo. Para a microalga Chlorella minutissima, foram avaliados os efeitos do meio de cultivo e das concentrações dos componentes nitrogenado e fosfatados utilizados no meio de cultivo da microalga sobre a concentração de carboidratos desta. Foram realizadas fermentações alcoólicas utilizando como substrato biomassa das microalgas Chlorella pyrenoidosa e Spirulina sp. LEB 18 acrescidos de glicose e sacarose. Para a microalga Chlorella homosphaera, a maior produtividade em carboidratos foi obtida nos ensaios realizados com a maior concentração de KNO3 com menor concentração de NaCl e menor concentração de KNO3 com maior concentração de NaCl (0,014±0,001 g.L-1 .d-1 e 0,015±0,002 g.L-1 .d-1 , respectivamente). A maior produtividade em carboidratos nos cultivos de Spirulina platensis LEB 52 (0,116±0,002 g.L-1 .d-1 ) foi verificada no experimento no qual a microalga foi cultivada nas menores concentrações de NaNO3 e NaCl. A microalga Spirulina platensis LEB 52 apresentou maior produtividade em carboidratos quando comparada à microalga Chlorella homosphaera. A microalga Chlorella minutissima cultivada em meio Basal, com adição de 0,125 g.L-1 do componente nitrogenado (KNO3) e sem adição dos componentes fosfatados (K2HPO4 e KH2PO4) apresentou a maior produtividade em carboidratos nos cultivos (0,030±0,002 g.L-1 .d-1 ). O ensaio com biomassa de Spirulina sp. LEB 18 com adição de glicose apresentou eficiência superior na formação de etanol e produtividade em etanol (68,487±2,592% e 1,182±0,051g.L-1 .h-1 , respectivamente).

Harvesting and Collection of Animal Forest Species

The harvest and trade of corals and other benthic organisms from the world’s shallow tropical reefs is a lucrative industry that can have positive socioeconomic benefits for communities while supplying the increasing demand specimens for aquaria and curios. For most countries, this trade has historically been almost entirely unregulated. More recently, in response to concerns about the rapid decline of some reefs in the face of anthropogenic and natural pressures, as well as indications of depletions and even localized extinctions of some species caused by harvesting, there have been attempts to improve the sustainability of the industry. Both developing and developed countries face different impediments to this reform, the most pressing and common of which is the lack of reliable data on world trade through CITES. Thereafter, differences in the processes through which reform can be implemented are based principally on the length of the supply chain from collection to export, the degree of industry stewardship, and resourcing. The coral collection fishery in Queensland, Australia, provides an example where continual improvements in reporting and risk assessments and adopting a comanagement approach are delivering better adaptive management of the resource, although the on-ground sustainability benefits of this approach are still to be tested. A simpler approach to sustainable use of coral is to favor the replacement of wild harvested specimens with those bred or grown entirely in an aquaculture facility (as opposed to merely collected and then grown out in culture). Yet there are major impediments to this change, including the dependence of many public aquaria on the same sources as the hobbyist community, difficulties of culturing some species in captivity, and infrastructure costs. Nevertheless, this approach will likely play an important part in reef conservation efforts in the future.

Cogestion des ressources naturelles : une approche structurale pour quantifier la contribution des réseaux d'acteurs à la résilience des systèmes socio-écologiques

Alors que les activités anthropiques font basculer de nombreux écosystèmes vers des régimes fonctionnels différents, la résilience des systèmes socio-écologiques devient un problème pressant. Des acteurs locaux, impliqués dans une grande diversité de groupes — allant d’initiatives locales et indépendantes à de grandes institutions formelles — peuvent agir sur ces questions en collaborant au développement, à la promotion ou à l’implantation de pratiques plus en accord avec ce que l’environnement peut fournir. De ces collaborations répétées émergent des réseaux complexes, et il a été montré que la topologie de ces réseaux peut améliorer la résilience des systèmes socio-écologiques (SSÉ) auxquels ils participent. La topologie des réseaux d’acteurs favorisant la résilience de leur SSÉ est caractérisée par une combinaison de plusieurs facteurs : la structure doit être modulaire afin d’aider les différents groupes à développer et proposer des solutions à la fois plus innovantes (en réduisant l’homogénéisation du réseau), et plus proches de leurs intérêts propres ; elle doit être bien connectée et facilement synchronisable afin de faciliter les consensus, d’augmenter le capital social, ainsi que la capacité d’apprentissage ; enfin, elle doit être robuste, afin d’éviter que les deux premières caractéristiques ne souffrent du retrait volontaire ou de la mise à l’écart de certains acteurs. Ces caractéristiques, qui sont relativement intuitives à la fois conceptuellement et dans leur application mathématique, sont souvent employées séparément pour analyser les qualités structurales de réseaux d’acteurs empiriques. Cependant, certaines sont, par nature, incompatibles entre elles. Par exemple, le degré de modularité d’un réseau ne peut pas augmenter au même rythme que sa connectivité, et cette dernière ne peut pas être améliorée tout en améliorant sa robustesse. Cet obstacle rend difficile la création d’une mesure globale, car le niveau auquel le réseau des acteurs contribue à améliorer la résilience du SSÉ ne peut pas être la simple addition des caractéristiques citées, mais plutôt le résultat d’un compromis subtil entre celles-ci. Le travail présenté ici a pour objectifs (1), d’explorer les compromis entre ces caractéristiques ; (2) de proposer une mesure du degré auquel un réseau empirique d’acteurs contribue à la résilience de son SSÉ ; et (3) d’analyser un réseau empirique à la lumière, entre autres, de ces qualités structurales. Cette thèse s’articule autour d’une introduction et de quatre chapitres numérotés de 2 à 5. Le chapitre 2 est une revue de la littérature sur la résilience des SSÉ. Il identifie une série de caractéristiques structurales (ainsi que les mesures de réseaux qui leur correspondent) liées à l’amélioration de la résilience dans les SSÉ. Le chapitre 3 est une étude de cas sur la péninsule d’Eyre, une région rurale d’Australie-Méridionale où l’occupation du sol, ainsi que les changements climatiques, contribuent à l’érosion de la biodiversité. Pour cette étude de cas, des travaux de terrain ont été effectués en 2010 et 2011 durant lesquels une série d’entrevues a permis de créer une liste des acteurs de la cogestion de la biodiversité sur la péninsule. Les données collectées ont été utilisées pour le développement d’un questionnaire en ligne permettant de documenter les interactions entre ces acteurs. Ces deux étapes ont permis la reconstitution d’un réseau pondéré et dirigé de 129 acteurs individuels et 1180 relations. Le chapitre 4 décrit une méthodologie pour mesurer le degré auquel un réseau d’acteurs participe à la résilience du SSÉ dans lequel il est inclus. La méthode s’articule en deux étapes : premièrement, un algorithme d’optimisation (recuit simulé) est utilisé pour fabriquer un archétype semi-aléatoire correspondant à un compromis entre des niveaux élevés de modularité, de connectivité et de robustesse. Deuxièmement, un réseau empirique (comme celui de la péninsule d’Eyre) est comparé au réseau archétypique par le biais d’une mesure de distance structurelle. Plus la distance est courte, et plus le réseau empirique est proche de sa configuration optimale. La cinquième et dernier chapitre est une amélioration de l’algorithme de recuit simulé utilisé dans le chapitre 4. Comme il est d’usage pour ce genre d’algorithmes, le recuit simulé utilisé projetait les dimensions du problème multiobjectif dans une seule dimension (sous la forme d’une moyenne pondérée). Si cette technique donne de très bons résultats ponctuellement, elle n’autorise la production que d’une seule solution parmi la multitude de compromis possibles entre les différents objectifs. Afin de mieux explorer ces compromis, nous proposons un algorithme de recuit simulé multiobjectifs qui, plutôt que d’optimiser une seule solution, optimise une surface multidimensionnelle de solutions. Cette étude, qui se concentre sur la partie sociale des systèmes socio-écologiques, améliore notre compréhension des structures actorielles qui contribuent à la résilience des SSÉ. Elle montre que si certaines caractéristiques profitables à la résilience sont incompatibles (modularité et connectivité, ou — dans une moindre mesure — connectivité et robustesse), d’autres sont plus facilement conciliables (connectivité et synchronisabilité, ou — dans une moindre mesure — modularité et robustesse). Elle fournit également une méthode intuitive pour mesurer quantitativement des réseaux d’acteurs empiriques, et ouvre ainsi la voie vers, par exemple, des comparaisons d’études de cas, ou des suivis — dans le temps — de réseaux d’acteurs. De plus, cette thèse inclut une étude de cas qui fait la lumière sur l’importance de certains groupes institutionnels pour la coordination des collaborations et des échanges de connaissances entre des acteurs aux intérêts potentiellement divergents.