24,929 research outputs found

    Desarrollo de papeles biocativos por injerto de moléculas específicas en celulosa

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    Tesis (DCI)--FCEFN-UNC, 2019En la presente tesis se presenta el desarrollo de papeles bioactivos con potencial aplicaci√≥n en el envasado activo de alimentos. Para tal fin, se propuso el injerto de eugenol, un compuesto de origen natural con propiedades antimicrobiana, antioxidante y repelente de insectos, en celulosa, utilizando √°cido policarbox√≠lico como agente ligante. Con el objetivo de evaluar la escalabilidad del proceso propuesto, se estudiaron distintas tecnolog√≠as de curado, tales como calentamiento por convecci√≥n, infrarrojo, microondas y conducci√≥n. En todos los casos, se analizaron la influencia de las variables operativas sobre el avance de la reacci√≥n y propiedades finales del papel preparado, utilizando un dise√Īo de experimentos Doehlert para elegir las experiencias a realizar, y analizando los resultados mediante metodolog√≠a de superficie de respuesta y an√°lisis estad√≠stico ANOVA. Se pudo comprobar que la reacci√≥n de injerto de eugenol en papel comercial se produjo con √©xito en todas las tecnolog√≠as estudiadas. Asimismo, se encontraron las condiciones √≥ptimas de reacci√≥n para cada una de las tecnolog√≠as, para lo cual se busc√≥ un compromiso entre el avance de la reacci√≥n y las propiedades finales del material (mec√°nicas y color). A partir de estas condiciones, se prepararon papeles y se realiz√≥ una caracterizaci√≥n m√°s espec√≠fica para su aplicaci√≥n como envase de alimentos comparando los papeles modificados con el papel virgen. Se analizaron las propiedades mec√°nicas por ensayo de tracci√≥n, rasgado y punzonado y se midi√≥ la absorci√≥n de agua y la capacidad de degradaci√≥n. Por otro lado, las propiedades bioactivas analizadas fueron la actividad antioxidante, antimicrobiana, repelente e insecticida de gorgojos (T. castaneum y R. dominica). Una vez probado que el papel modificado presenta buenas caracter√≠sticas f√≠sicas y bioactivas para su posible aplicaci√≥n en el envasado de alimentos, se realizaron prototipos de envasado para harina, como alimento representativo de alimentos derivados de cereales, susceptibles al ataque de plagas. En este estudio se analiz√≥ la migraci√≥n de reactivos, propiedades organol√©pticas y conservaci√≥n del alimento, arrojando resultados promisorios para la industria de envases de alimentos. Finalmente, se realiz√≥ una comparaci√≥n de las tecnolog√≠as de curado ensayadas, analizando diferentes aspectos como avance de reacci√≥n, propiedades finales, apariencia, tiempo de reacci√≥n, consumo de energ√≠a, entre otros, como as√≠ tambi√©n disponibilidad y uso de estas tecnolog√≠as a escala industrial, seleccionando la tecnolog√≠a de conducci√≥n como la m√°s adecuada para una propuesta de escalado industrial.Fil: Muratore, Florencia. Universidad Nacional de C√≥rdoba. Facultad de Ciencias Exactas, F√≠sicas y Naturales; Argentina.Fil: Muratore, Florencia. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Instituto de Investigaci√≥n y Desarrollo en Ingenier√≠a de Procesos y Qu√≠mica Aplicada; Argentina

    Identifying and responding to people with mild learning disabilities in the probation service

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    It has long been recognised that, like many other individuals, people with learningdisabilities find their way into the criminal justice system. This fact is not disputed. Whathas been disputed, however, is the extent to which those with learning disabilities arerepresented within the various agencies of the criminal justice system and the ways inwhich the criminal justice system (and society) should address this. Recently, social andlegislative confusion over the best way to deal with offenders with learning disabilities andmental health problems has meant that the waters have become even more muddied.Despite current government uncertainty concerning the best way to support offenders withlearning disabilities, the probation service is likely to continue to play a key role in thesupervision of such offenders. The three studies contained herein aim to clarify the extentto which those with learning disabilities are represented in the probation service, toexamine the effectiveness of probation for them and to explore some of the ways in whichprobation could be adapted to fit their needs.Study 1 and study 2 showed that around 10% of offenders on probation in Kent appearedto have an IQ below 75, putting them in the bottom 5% of the general population. Study 3was designed to assess some of the support needs of those with learning disabilities in theprobation service, finding that many of the materials used by the probation service arelikely to be too complex for those with learning disabilities to use effectively. To addressthis, a model for service provision is tentatively suggested. This is based on the findings ofthe three studies and a pragmatic assessment of what the probation service is likely to becapable of achieving in the near future

    Consent and the Construction of the Volunteer: Institutional Settings of Experimental Research on Human Beings in Britain during the Cold War

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    This study challenges the primacy of consent in the history of human experimentation and argues that privileging the cultural frameworks adds nuance to our understanding of the construction of the volunteer in the period 1945 to 1970. Historians and bio-ethicists have argued that medical ethics codes have marked out the parameters of using people as subjects in medical scientific research and that the consent of the subjects was fundamental to their status as volunteers. However, the temporality of the creation of medical ethics codes means that they need to be understood within their historical context. That medical ethics codes arose from a specific historical context rather than a concerted and conscious determination to safeguard the well-being of subjects needs to be acknowledged. The British context of human experimentation is under-researched and there has been even less focus on the cultural frameworks within which experiments took place. This study demonstrates, through a close analysis of the Medical Research Council's Common Cold Research Unit (CCRU) and the government's military research facility, the Chemical Defence Experimental Establishment, Porton Down (Porton), that the `volunteer' in human experiments was a subjective entity whose identity was specific to the institution which recruited and made use of the subject. By examining representations of volunteers in the British press, the rhetoric of the government's collectivist agenda becomes evident and this fed into the institutional construction of the volunteer at the CCRU. In contrast, discussions between Porton scientists, staff members, and government officials demonstrate that the use of military personnel in secret chemical warfare experiments was far more complex. Conflicting interests of the military, the government and the scientific imperative affected how the military volunteer was perceived

    Changes in sediment methanogenic archaea community structure and methane production potential following conversion of coastal marsh to aquaculture ponds

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    Widespread conversion of coastal wetlands into aquaculture ponds in the Chinese coastal region often results in degradation of the wetland ecosystems, but its effects on sediment‚Äôs potential to produce greenhouse gases remain unclear. Using field sampling, incubation experiments and molecular analysis, we studied the sediment CH4 production potential and the relevant microbial communities in a brackish marsh and the nearby aquaculture ponds in the Min River Estuary in southeastern China. Sediment CH4 production potential was higher in the summer and autumn months than in spring and winter months, and it was best correlated with sediment carbon content among all environmental variables. The mean sediment CH4 production potential in the aquaculture ponds (20.1 ng g‚Äď1 d‚Äď1) was significantly lower than that in the marsh (45.2 ng g‚Äď1 d‚Äď1). While Methanobacterium dominated in both habitats (41-59%), the overall composition of sediment methanogenic archaea communities differed significantly between the two habitats (p<0.05) and methanogenic archaea alpha diversity was lower in the aquaculture ponds (p<0.01). Network analysis revealed that interactions between sediment methanogenic archaea were much weaker in the ponds than in the marsh. Overall, these findings suggest that conversion of marsh land to aquaculture ponds significantly altered the sediment methanogenic archaea community structure and diversity and lowered the sediment‚Äôs capacity to produce CH4

    Aflatoxins

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    The aflatoxin producing fungi Aspergillus flavus, A. parasiticus, and A. nomius, although they are also produced by other species of Aspergillus as well as by Emericella spp.(Telemorph). There are many types of aflatoxins, but the four main ones are aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), and aflatoxin G2 (AFG2, while aflatoxin M1 (AFM1) and M2 (AFM2) are the hydroxylated metabolites of AFB1 and AFB2. Aflatoxin B1, which is a genotoxic hepatocarcinogen, which presumptively causes cancer by inducing DNA, adducts leading to genetic changes in target liver cells. Cytochrome-P450 enzymes to the reactive intermediate AFB1‚Äď8, 9 epoxide (AFBO) which binds to liver cell DNA, resulting in DNA adducts, metabolize AFB1 Ingestion of contaminated food is the main source of exposure to aflatoxins, which adversely affect the health of both humans and animals. The compounds can cause acute or chronic toxic effects of a teratogenic, mutagenic, carcinogenic, immunotoxic or hepatotoxic character. You can reduce your aflatoxin exposure by buying only major commercial brands of food and by discarding that look moldy, discolored, or shriveled

    Understanding the Responses, Mechanism and Development of Salinity Stress Tolerant Cultivars in Rice

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    Rice is the most important staple food crop of much of the world’s population. Production and consumption of rice is higher in Asia but adverse environmental conditions critically threaten the rice production. Soil salinity has been a key abiotic constraint affecting the crop production by reducing growth, development and yield of the plant. Rice is highly sensitive to salinity specifically at the early vegetative and late reproductive stages. Therefore, studying the responses of crop at the morphological, physiological, biochemical and molecular level is an effective strategy. Understanding the mechanisms behind the salinity such as osmotic stress and osmolytes, ion exclusion, inclusion and compartmentation, antioxidant response and hormonal regulation. Different screening strategies such as phenotypic and genotypic screening for rice under salinity and select the salt tolerant lines. Using the conventional and molecular breeding approaches is a prerequisite for its effective management and to develop salt tolerant cultivars in rice

    Persistent Organic Pollutants in the Bizerte Lagoon Ecosystem: Occurrence, Distribution, and Ecotoxicological Assessment Using Marine Organism

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    Marine ecosystem represents an ecologically and economically important water bodies for human and animal living. Their increasing pollution by persistent organic pollutants has represented a major environmental alarm during the last years. In the current study, we examined the occurrence, local distribution and ecotoxicological menace of organic pollutants, comprising brominated flame retardants (BFR), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) in different matrices from the Northern Tunisian Coastal Ecosystem (Bizerte lagoon). The pollutant existence in this biome is related with a negative impact on the biocenosis health. Many approach including (i) chemical analyses; (ii) taxonomic structure and ecological indices analyses; (iii) and biochemical experimental studies, were investigated to determine the ecosystem quality and the contaminant effects. Our chapter introduces the baseline information on the organic contaminations extent and toxicological impact, as well as, it contribute to evaluate the ecological quality of this marine coastal ecosystem
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