Characterization of Atrazine-Loaded Biodegradable Poly(Hydroxybutyrate-Co-Hydroxyvalerate) Microspheres

Polyhydroxybutyrate-co-hydroxyvalerate microspheres (PHBV-MS) were prepared as a delivery system for the herbicide atrazine (ATZ). Characterization of the system included investigation of in vitro release properties and genotoxicity. ATZ - PHBV-MS particle diameters showed a size distribution range of 1-13 mu m. Differential scanning calorimetry analyses indicated that ATZ was associated with the PHBV microparticles. The release profiles showed a different release behavior for the pure herbicide in solution, as compared with that containing ATZ-loaded PHBV-MS. Korsmeyer-Peppas model analyses showed that atrazine release from the microparticles occurred by a combination of diffusion through the matrix and partial diffusion through water-filled pores of the PHBV microparticles. A Lactuca sativa test result showed that the genotoxicity of ATZ-loaded PHBV-MP was decreased in relation to ATZ alone. The results demonstrate a viable biodegradable herbicide release system using atrazine for agrochemical purposes.

Institutions de microfinance et prêteurs informels de l’agriculture familiale en Côte d’ivoire : de la cohabitation à la fusion

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Food-Web Complexity in Guaymas Basin Hydrothermal Vents and Cold Seeps

In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB) cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA) cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemosynthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities, foundation species may have the potential to partly release the competitive pressure within communities of low fluid-flux habitats. Finally, ecosystem functioning in vents and seeps was highly similar despite environmental differences (e.g. physico-chemistry, dominant basal sources) suggesting that ecological niches are not specifically linked to the nature of fluids. This comparison of seep and vent functioning in the Guaymas basin thus provides further supports to the hypothesis of continuity among deep-sea chemosynthetic ecosystems.

RISKS TO FOOD AVAILABILITY AND ACCESS FROM CLIMATE POLICIES: AN INTEGRATED ASSESSMENT OF REGIONAL FOOD AVAILABILITY AND ACCESS WITH ALTERNATIVE CLIMATE MITIGATION STRATEGIES TO 2050

Although mitigating GHG emissions is necessary to reduce the overall negative climate change impacts on crop yields and agricultural production, certain mitigation measures may generate unintended consequences to food availability and access due to land use competition and economic burden of mitigation. Prior studies have examined the co-impacts on food availability and global producer prices caused by alternative climate policies. More recent studies have looked at the reduction in total caloric intake driven by both changing income and changing food prices under one specific climate policy. However, due to inelastic calorie demand, consumers’ well-being are likely further reduced by increased food expenditures. Built upon existing literature, my dissertation explores how alternative climate policy designs might adversely affect both caloric intake and staple food budget share to 2050, by using the Global Change Assessment Model (GCAM) and a post-estimated metric of food availability and access (FAA). My dissertation first develop a set of new metrics and methods to explore new perspectives of food availability and access under new conditions. The FAA metric consists of two components, the fraction of GDP per capita spent on five categories of staple food and total caloric intake relative to a reference level. By testing the metric against alternate expectations of the future, it shows consistent results with previous studies that economic growth dominates the improvement of FAA. As we increase our ambition to achieve stringent climate targets, two policy conditions tend to have large impacts on FAA driven by competing land use and increasing food prices. Strict conservation policies leave the competition between bioenergy and agriculture production on existing commercial land, while pricing terrestrial carbon encourages large-scale afforestation. To avoid unintended outcomes to food availability and access for the poor, pricing land emissions in frontier forests has the advantage of selecting more productive land for agricultural activities compared to the full conservation approach, but the land carbon price should not be linked to the price of energy system emissions. These results are highly relevant to effective policy-making to reduce land use change emissions, such as the Reduced Emissions from Deforestation and Forest Degradation (REDD).

Enhancement of ion dynamics in organic ionic plastic crystal/PVDF composite electrolytes prepared by co-electrospinning

Electrospun fibers are widely used in composite material design and fabrication due to their high aspect ratio, high surface area and favorable mechanical properties. In this report, novel organic ionic plastic crystal (OIPC) modified poly(vinylidene difluoride) (PVDF) composite fiber membranes were prepared by electrospinning. These composite materials are of interest for application as solid electrolytes in devices including lithium and sodium batteries. The influence of the OIPC, N-ethyl-N-methylpyrrolidinium tetrafluoroborate [C2mpyr][BF4], on the morphology and phase behavior of the composite fibers was investigated by scanning electron microscopy and Fourier transform infrared spectroscopy. Compared with pure electrospun PVDF fibers, which have an electroactive β phase and a small amount of non-polar α phase, the ion-dipole interaction between OIPC and the polymer in the co-electrospun composite system can reduce the non-polar α phase PVDF, resulting in almost entirely electroactive β phase PVDF. Differential scanning calorimetry shows that the ion-dipole interaction between the OIPC and PVDF can also interrupt the crystalline structure of the OIPC. Solid state NMR analysis also reveals different molecular dynamics of the [C2mpyr][BF4] in co-electrospun fibers compared with pure OIPC. Thus, electrospun [C2mpyr][BF4]/PVDF composite fibers that combine both increased ionic conductivity and almost pure β phase PVDF are demonstrated.

Survival and fermentation activity of probiotic bacteria and oxidative stability of omega-3 oil in co-microcapsules during storage

Tuna oil (O) and probiotic bacteria Lactobacillus casei (P) were co-microencapsulated in whey protein isolate (WPI)-gum Arabic (GA) complex coacervate. The co-microcapsules (WPI-P-O-GA), L. casei microcapsules (WPI-P-GA) and tuna oil microcapsules (WPI-O-GA) were converted into powder using spray and freeze drying. The interaction between probiotic bacteria and omega-3 oil in co-microcapsules, particularly in terms of oxidative stability of omega-3 oil and vitality/viability of probiotic bacteria and any synergistic outcome, was studied. The effect of storage temperature (5 and 25 °C) and time (90 days) on the survival and fermentation activity of L. casei and oxidative stability of tuna oil in the microcapsules/co-microcapsules was determined. A synergism between oxidative stability of omega-3 oil and vitality of probiotic bacteria was observed, when they were co-microencapsulated and spray dried. These co-microcapsules will likely have utility in functional food formulations due to simple and cost effective stabilisation and delivery of two important functional ingredients.

Dietary niche overlap of free-roaming dingoes and domestic dogs: the role of human provided food

As both companion animals and opportunistic predators, dogs (Canis lupus spp.) have had a long and complex relationship with humans. In Australia, the dingo (C. l. dingo) was introduced 4,000 years ago and, other than humans, is now the continent's top mammalian predator. Domestic dogs (C. l. familiaris) were introduced by Europeans more recently and they interbreed with dingoes. This hybridization has caused growing concern about the roles that domestic dogs and dingoes play in shaping ecosystem processes. There is also considerable debate about whether anthropogenic environmental changes can alter the ecological roles of dingoes. We used scat analysis to test whether the dingo, as the longer-established predator, occupies a different dietary niche from that of free-roaming domestic dogs, irrespective of human influence. Our results demonstrate considerable dietary overlap between dingoes and domestic dogs in areas where humans provide supplementary food, providing evidence against our hypothesis. However, the consumption by dingoes of a greater diversity of prey, in association with historical differences in the interactions between dingoes and humans, suggests a partial separation of their dietary niche from that of domestic dogs. We conclude that anthropogenic changes in resource availability could prevent dingoes from fulfilling their trophic regulatory or pre-European roles. Effective management of human-provided food is therefore required urgently to minimize the potential for subsidized populations of dingoes and domestic dogs to negatively affect co-occurring prey.

Análisis del sector del food service a partir del modelo de competitividad de Michael Porter para determinar la viabilidad de incursión de la empresa Bakery Service Foods

Las Mipymes son un componente fundamental para el desarrollo económico y social de cualquier país, en especial de un país como Colombia en donde representan el 99,9% de las empresas actualmente constituidas, concentrando el 81% de los empleados a nivel nacional (Fedesarrollo, 2013). Aunque juegan un papel protagónico en la economía colombiana, las Mipymes aún deben recorrer un camino extenso para poder explotar todo el potencial con el que cuentan, puesto que presentan un alto índice de mortandad empresarial en los primeros años de funcionamiento, esto evidenciado en los resultados del estudio GEM (Global Entrepreneurship Monitor, 2009) en donde se encontró que sólo el 12,61% de los negocios lograron superar los 42 meses de permanencia en el mercado (El País, 2010) principalmente a causa de la ausencia de una planeación estratégica de largo plazo que les permita a los negocios emprendedores del país alcanzar la competitividad. Si bien es cierto que crear empresa es relativamente sencillo, son múltiples los retos tanto internos como externos que deben enfrentar las organizaciones para poder alcanzar una etapa de madurez empresarial, sobre todo en los primeros años de funcionamiento que son los más críticos y decisivos para el futuro de cualquier empresa, es por esto que se hace indispensable emplear estrategias que les permitan ser sostenibles a largo plazo, en un entorno altamente competitivo por empresas tanto nacionales como internacionales, siendo este uno de los propósitos fundamentales al que deberían apostar los empresarios colombianos para crear un impacto positivo en la sociedad y aportar a la competitividad nacional. Bakery Service Foods, es una empresa dedicada a la comercialización y distribución de insumos de panadería con sede en el barrio Carvajal en la ciudad de Bogotá. Desde su constitución, el 29 de diciembre de 2008, la empresa ha buscado posicionarse en un mercado en donde tanto empresas grandes como Grasco, Grupo Team, Sigra, Duquesa, Conaceites, Alvarado, Aceites Finos; así como microempresas sin infraestructura ni solidez económica, componen un entorno altamente competitivo y hacinado que representa un desafío para una pequeña empresa familiar que no cuenta con un músculo financiero significativo. Por otra parte, Bakery Service Foods a traviesa por un período de alta incertidumbre debido a que el proveedor que representa el 85% de las ventas de los productos a los cuales representan, FANAGRA S.A, atraviesa por una completa reestructuración debido a la venta de dicha empresa a una multinacional suiza. Esta situación representa un alto riesgo para la compañía y exige que se emprendan acciones oportunas que les permitan reducir la alta dependencia en un único proveedor. Teniendo en cuenta que una de las ambiciones desde la fundación de la compañía ha sido incursionar y ser una empresa competitiva en el mercado de Food Service, que perdure en el tiempo, ¿Qué tan viable es diversificar el portafolio de la empresa Bakery Service Foods (BSF) en el mercado Food Service? Con este proyecto se busca diseñar una propuesta de diversificación de portafolio para la empresa Bakery Service Foods (BSF) analizando el mercado Food Service, por medio del modelo de Ventaja Competitiva de Michael Porter; lo anterior, con el propósito de que la empresa se consolide en este mercado como un aliado estratégico para sus clientes y representados, y con un modelo de negocio sostenible a largo plazo. Finalmente, se espera que a través de la propuesta de mejora para Bakery Service Foods, se afiancen los conocimientos administrativos obtenidos durante el pregrado en Administración de Empresas, aplicando satisfactoriamente las herramientas, metodologías y bases conceptuales adquiridas, para enriquecer el proceso de aprendizaje profesional y aportar valor a una empresa colombiana desde el mercado de Food Service.

Bioactivity of Ruta graveolens and Satureja montana Essential Oils on Solanum tuberosum Hairy Roots and Solanum tuberosum Hairy Roots with Meloidogyne chitwoodi Co-cultures

As a nematotoxics screening biotechnological system, Solanum tuberosum hairy roots (StHR) and S. tuberosum hairy roots with Meloidogyne chitwoodi co-cultures (StHR/CRKN) were evaluated, with and without the addition of the essential oils (EOs) of Satureja montana and Ruta graveolens. EOs nematotoxic and phytotoxic effects were followed weekly by evaluating nematode population density in the co-cultures as well as growth and volatile profiles of both in vitro cultures types. Growth, measured by the dissimilation method and by fresh and dry weight determination, was inhibited after EO addition. Nematode population increased in control cultures, while in EO-added cultures numbers were kept stable. In addition to each of the EOs main components, and in vitro cultures constitutive volatiles, new volatiles were detected by gas chromatography and gas chromatography coupled to mass spectrometry in both culture types. StHR with CRKN co-cultures showed to be suitable for preliminary assessment of nematotoxic EOs.

An investigation of contact transmission of methicillin-resistant staphylococcus aureus

Hand hygiene is critical in the healthcare setting and it is believed that methicillin-resistant Staphylococcus aureus (MRSA), for example, is transmitted from patient to patient largely via the hands of health professionals. A study has been carried out at a large teaching hospital to estimate how often the gloves of a healthcare worker are contaminated with MRSA after contact with a colonized patient. The effectiveness of handwashing procedures to decontaminate the health professionals' hands was also investigated, together with how well different healthcare professional groups complied with handwashing procedures. The study showed that about 17% (9–25%) of contacts between a healthcare worker and a MRSA-colonized patient results in transmission of MRSA from a patient to the gloves of a healthcare worker. Different health professional groups have different rates of compliance with infection control procedures. Non-contact staff (cleaners, food services) had the shortest handwashing times. In this study, glove use compliance rates were 75% or above in all healthcare worker groups except doctors whose compliance was only 27%.