970 resultados para liposome stabilization
Resumo:
In-package pasteurization is the most used method for beer microbiological stabilization. The search for safer and better quality food has created a need to better understand the processes involved in producing it. However, little is known about the temperature and velocity profiles during the thermal processes of liquid foods in commercial packaging, which results in over-dimensioned processes to guarantee safety, decreasing the sensorial and nutritional characteristics of the product and increasing process costs. Simulations using Computational Fluid-Dynamics (CFD) have been used by various authors to evaluate those processes. The objective of the present paper was to evaluate the effect of packaging orientation in the pasteurization of beer in a commercial aluminum can using CFD. A heating process was simulated at 60 ºC up to 15 PUs (a conventional beer process, in which 1 Pasteurization Unit (PU) is equivalent to 1minute at 60 ºC). The temperature profile and convection current velocity along the process and the variation of the PUs were evaluated in relation to time considering the cans in the conventional, inverted, and horizontal positions. The temperature and velocity profiles were similar to those presented in the literature. The package position did not result in process improvement.
Resumo:
Rice bran is a byproduct commonly used for animal feeding; however its nutritional value and potential application in human diet have attracted market interest. Its preservation for safe use is still a challenge, so the objective of this study was to determine the quality of commercially available rice bran samples subjected to different heat treatments (extruding, parboiling, toasting, and microwave oven heating) in order to promote stabilization during storage under room temperature. Rice bran samples were collected from two industries, and each treatment was divided in three parts, each corresponding to three repetitions. All samples were evaluated for moisture content, total microorganisms, mold and yeast counting, hydrolytic rancidity, and lipase activity during 90 days of storage. Most of the heat treatments, including domestic and thermoplastic extrusion, generated products which may be used for human consumption under the tested conditions in terms of physicochemical and microbiological quality. The domestic treatments were more efficient in eliminating microorganisms or keeping them within acceptable limits. The toasted rice bran showed satisfactory results in terms of moisture, hydrolytic rancidity control, and lipase activity.
Resumo:
The hydration kinetics of five barley cultivars was studied at six different temperatures ranging from 10 to 35 ºC for 32 hours applying the Peleg model. Response Surface was used to describe dynamic of the process and identify the hydration time for each cultivar. The activation energy (Ea), enthalpy (ΔH*), entropy (ΔS*), and Gibbs free energy (ΔG*) were estimated from the adjusted parameters and Arrhenius equation. Temperature had significant effect on the hydration of the five cultivars. At low temperatures, the stabilization time for hydration was faster. Peleg constants K1 and K2 decreased with increasing temperature. The cultivar BRS BRAU showed the lowest value of initial absorption rate (R0 = 0.149 kg.h-1) at 10 ºC, while the cultivar BRS BOREMA had the highest value of R0 (0.367 kg.h-1 at 35 ºC). The equilibrium moisture content (Me) increased with increasing temperature. The cultivars BRS CAUE and BRS BRAU showed the lowest values of Ea, ΔH*, ΔS* showed negative values, and ΔG* increased with increasing temperature, confirming the effect of temperature on hydration.
Resumo:
The 1980s' debt crisis is a landmark in developing economies' growth and stabilization. According to the most quoted empirical articles, external shocks and vicissitudes gave rise to crisis just because of delays in stabilization policies, engendered by internal conflicts and institutional immaturity. I review some of these papers, and find out some problems - in the measurement of shocks and foreign indebtedness, namely - whose corrections lead to opposite results: external shocks and foreign indebtedness explain that crisis regardless of domestic policies. At the same time, the strong correlation of income distribution to terms of trade changes and foreign indebtedness suggest that inequality may have contributed differently to that crisis: either through an economic channel, or through a political channel based on delays in reforms.
Resumo:
This paper analyses the relationship between bargaining outcomes in seventeen units regarding the manufacturing sector in Rio Grande do Sul, and change in the relevant economic environment from 1979 to 1995. Theories on the determinants of bargaining outcomes are discussed in order to provide a basis for hypothesizing about the specific case. Statistical outcomes suggest that collective bargaining have been basically influenced by unemployment, manufacturing relative prices, the stabilization policies starting in 1986, and, specifically for negotiated minimum wages, change in the official rates of minimum wages.
Resumo:
Tässä kanditaatintyössä selvitettiin kuinka erilaiset sideaineseokset soveltuvat raskas-metallien sitomiseen 28 vuorokautta stabiloiduissa näytteistä. Työssä oletettiin teollisten jätefraktioiden käytön tehostavan eräiden metallien, kuten kupari ja sinkki, immobilisointia lievästi pilaantuneista maa-aineksista. Kokeellisessa osassa stabiloitiin Kokkolan satamasta ruopattua sedimenttiä, jonka sinkkipitoisuudet olivat ylittäneet saastuneen sedimentin ohjearvon (≥400 mg/kg). Sedimenttiin lisättiin eri sideaineseoksia ja näytteiden annettiin stabiloitua 28 vuorokautta, minkä jälkeen niistä testattiin liukenevat raskasmetallit muokatulla ravistelutestillä. Eri sideaineseoksilla saatuja tuloksia verrattiin pelkän yleissementin käyttöön. Lisäksi erillisistä näytteistä otettiin pyyhkäisyelektronimikros-koopilla (SEM) kuvia havainnollistamaan stabiloitumista. Näissä näytteissä käytettiin samoja sideaineita kuin tehdyissä kokeissa. Liukoisuustestien tuloksista voidaan huomata näytteissä ongelmalliseksi raskasmetalliksi identifioidun sinkin sitoutuvan parhaiten sementin ja kipsin sekoituksella. Myös tuhkaa sisältävät sideainesekoitukset pienensivät sinkin liukoisuutta verrattuna pelkkään yleis-sementtiin. Jatkotutkimuksissa voitaisiin testata erilaisia sideainesekoituksia betonira-kentamisessa, joilla saadaan ainakin 25 MPa lujuusarvo, pilaantunutta sedimenttiä tai maa-ainesta käyttäen.
Resumo:
The global economic crisis has created an opportunity to rethink macroeconomics for development. Such rethinking is both necessary and desirable. It is essential to redefine macroeconomic objectives so that the emphasis is on fostering employment creation and supporting economic growth instead of the focus on price stability alone. It is just as important to rethink macroeconomic policies which cannot simply be used for the management of inflation and the elimination of macroeconomic imbalances, since fiscal and monetary policies are powerful and versatile instruments in the pursuit of development objectives. In doing so, it is essential to the overcome the constraints embedded in orthodox economic thinking and recognize the constraints implicit in the politics of ideology and interests.
Resumo:
This paper aims at evaluating the conduction of monetary policy after the adoption of inflation targeting. Formation of Selic rate is modeled by estimating a reaction function of the BCB. Results show an excessive degree of interest rate smoothing and a high level of equilibrium interest rate. This evidence supports the belief that Selic rate's formation is ruled by a conservative behavior. The conservative conduction of monetary policy is related to two distinct features of BCB's reaction function: i) the great weight of autoregressive components; and, chiefly, ii) a very high level of the equilibrium interest rate. The main conclusion is that, all remaining unchanged, the interest rate would hardly be reduced in a satisfactory way. Massive and chronic deflation would be needed if Selic were to reach a reasonable level, closer to that of rates in the rest of the world. This evidences the need for a debate on the adequacy of current stabilization strategy.
Resumo:
Molecular oxygen (O2) is a key component in cellular respiration and aerobic life. Through the redox potential of O2, the amount of free energy available to organisms that utilize it is greatly increased. Yet, due to the nature of the O2 electron configuration, it is non-reactive to most organic molecules in the ground state. For O2 to react with most organic compounds it must be activated. By activating O2, oxygenases can catalyze reactions involving oxygen incorporation into organic compounds. The oxygen activation mechanisms employed by many oxygenases to have been studied, and they often include transition metals and selected organic compounds. Despite the diversity of mechanisms for O2 activation explored in this thesis, all of the monooxygenases studied in the experimental part activate O2 through a transient carbanion intermediate. One of these enzymes is the small cofactorless monooxygenase SnoaB. Cofactorless monooxygenases are unusual oxygenases that require neither transition metals nor cofactors to activate oxygen. Based on our biochemical characterization and the crystal structure of this enzyme, the mechanism most likely employed by SnoaB relies on a carbanion intermediate to activate oxygen, which is consistent with the proposed substrate-assisted mechanism for this family of enzymes. From the studies conducted on the two-component system AlnT and AlnH, both the functions of the NADH-dependent flavin reductase, AlnH, and the reduced flavin dependent monooxygenase, AlnT, were confirmed. The unusual regiochemistry proposed for AlnT was also confirmed on the basis of the structure of a reaction product. The mechanism of AlnT, as with other flavin-dependent monooxygenases, is likely to involve a caged radical pair consisting of a superoxide anion and a neutral flavin radical formed from an initial carbanion intermediate. In the studies concerning the engineering of the S-adenosyl-L-methionine (SAM) dependent 4-O-methylase DnrK and the homologous atypical 10-hydroxylase RdmB, our data suggest that an initial decarboxylation of the substrate is catalyzed by both of these enzymes, which results in the generation of a carbanion intermediate. This intermediate is not essential for the 4-O-methylation reaction, but it is important for the 10-hydroxylation reaction, since it enables substrate-assisted activation of molecular oxygen involving a single electron transfer to O2 from a carbanion intermediate. The only role for SAM in the hydroxylation reaction is likely to be stabilization of the carbanion through the positive charge of the cofactor. Based on the DnrK variant crystal structure and the characterizations of several DnrK variants, the insertion of a single amino acid in DnrK (S297) is sufficient for gaining a hydroxylation function, which is likely caused by carbanion stabilization through active site solvent restriction. Despite large differences in the three-dimensional structures of the oxygenases and the potential for multiple oxygen activation mechanisms, all the enzymes in my studies rely on carbanion intermediates to activate oxygen from either flavins or their substrates. This thesis provides interesting examples of divergent evolution and the prevalence of carbanion intermediates within polyketide biosynthesis. This mechanism appears to be recurrent in aromatic polyketide biosynthesis and may reflect the acidic nature of these compounds, propensity towards hydrogen bonding and their ability to delocalize π-electrons.
Resumo:
The main goal of our paper is to provide analytical arguments to explain why Brazil has not been able to restore its long-term capacity for economic growth, especially compared with its economy in the 1950-1979 period (7.3 per cent per year on average) or even with a select number of emerging economies in the 1980-2010 period(6.7 per cent per year on average, against 2.3 per cent per year on average in Brazil in the same period). We build our idea of convention to growth based on the Keynesian concept of convention. For our purposes, this concept could be briefly summarized as the way in which the set of public and private economic decisions related to different objectives, such as how much to produce and invest, how much to charge for products and services, how to finance public and private debt, how to finance research and development, and so on, are indefinitely - or at least until there is no change- carried out by the political, economic and social institutions. This analytical reference can be connected to the Neo-Schumpeterian National Innovation System (NIS) concept, which emphasizes not only institutions associated with science and technology per se, but also the complex interaction among them and other institutions. In this paper we identify two conventions to long-term growth in the last three decades in Brazil: the liberal and the neo-developmental. We show that the poor performance in the Brazilian economy in terms of real GDP growth from the 1980s on can be explained by a weak coordination between short-term macroeconomic policies and long-term industrial and technological policies. This weak coordination, in turn, can be associated with the prevalence of the liberal convention from the 1990s on, which has emphasized price stabilization to the detriment of a neo-developmental strategy whose primary goal is to sustain higher rates of growth and full employment in Brazil.
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The paper analyzes the shortcomings of the Real Plan combining political science and economics, considering evidences on difficulties in implementing a complete plan of deindexation, namely: the distributional conflict, the corporatist relations between the State and society and the bureaucratic isolation of a highly specialized technocracy. The announcement of the plan triggered defensive reactions, fueling distributive tensions during the URV period, forcing the economic team to take measures that contradicted the overall guidelines followed. The persistence of indexation mechanisms indicate the resulting obstacles in seeking a reform of the State through a stabilization plan, even though the latter has the former as a precondition.
Resumo:
The paper analyzes the contributions of Mário Henrique Simonsen to the construction of the concept of inertial inflation and to its connected literature. Simonsen's curve, in which the idea of inertial inflation was implicit, is analyzed, alongside with the feedback model (modelo de realimentação) and it's shown how Simonsen built a model which considered inflationary inertia, neutralization possibilities and possible problems and costs of stabilization, anticipating many of the issued that guided the debate in the 1980s.
Resumo:
The signalling sphingolipid sphingosine-1-phosphate (S1P) is necessary for development of the immune system and vasculature and on a cellular level regulates migration, proliferation and survival. Due to these traits S1P has an important role in cancer biology. It is considered a primarily cancer-promoting factor and the enzyme which produces it, sphingosine kinase (SphK), is often over-expressed in tumours. S1P is naturally present in the blood, lymph, tissue fluids and cell cytoplasm and functions through its cell surface receptors (S1P1-5) and as an intracellular second messenger. Sphingosylphosphorylcholine (SPC) is closely related to S1P and has similar regulatory functions but has not been extensively studied. Both S1P and SPC are able to evoke either stimulatory or inhibitory effects on cancer cells depending on the context. The aim of this thesis work was to study novel regulatory targets of S1P and SPC, which mediate the effects of S1P/SPC signalling on cancer cell behaviour. The investigated targets are the transcription factor hypoxia-inducible factor 1 (HIF-1), the intermediate filament protein vimentin and components of the Hippo signalling pathway. HIF-1 has a central role in cancer biology, as it regulates a multitude of cancer-related genes and is potently activated by intratumoural hypoxia through stabilization of the regulatory subunit HIF-1α. Tumours typically harbour high HIF-1α levels and HIF-1, in turn, facilitates tumour angiogenesis and metastasis and regulates cancer cell metabolism. We found S1P to induce follicular thyroid cancer cell migration in normal oxygen conditions by increasing HIF-1α synthesis and stability and subsequently HIF-1 activity. Vimentin is a central regulator of cell motility and is also commonly over-expressed in cancers. Vimentin filaments form a cytoskeletal network in mesenchymal cells as well as epithelial cancer cells which have gone through epithelial-mesenchymal transition (EMT). Vimentin is heavily involved in cancer cell invasion and gives tumours metastatic potential. We saw both S1P and SPC induce phosphorylation of vimentin monomers and reorganization of the vimentin filament network in breast and anaplastic thyroid cancer cells. We also found vimentin to mediate the anti-migratory effect of S1P/SPC on these cells. The Hippo pathway is a novel signalling cascade which controls cancer-related processes such as cellular proliferation and survival in response to various extracellular signals. The core of the pathway consists of the transcriptional regulators YAP and TAZ, which activate predominantly cancer-promoting genes, and the tumour suppressive kinases Lats1 and Lats2 which inhibit YAP/TAZ. Increased YAP expression and activity has been reported for a wide variety of cancers. We found SPC to regulate Hippo signalling in breast cancer cells in a two-fold manner through effects on phosphorylation status, activity and/or expression of YAP and Lats2. In conclusion, this thesis reveals new details of the signalling function of S1P and SPC and regulation of the central oncogenic factors HIF-1 and vimentin as well as the novel cancer-related pathway Hippo.
Resumo:
The present world energy production is heavily relying on the combustion of solid fuels like coals, peat, biomass, municipal solid waste, whereas the share of renewable fuels is anticipated to increase in the future to mitigate climate change. In Finland, peat and wood are widely used for energy production. In any case, the combustion of solid fuels results in generation of several types of thermal conversion residues, such as bottom ash, fly ash, and boiler slag. The predominant residue type is determined by the incineration technology applied, while its composition is primarily relevant to the composition of fuels combusted. An extensive research has been conducted on technical suitability of ash for multiple recycling methods. Most of attention was drawn to the recycling of the coal combustion residues, as coal is the primary solid fuel consumed globally. The recycling methods of coal residues include utilization in a cement industry, in concrete manufacturing, and mine backfilling, to name few. Biomass combustion residues were also studied to some extent with forest fertilization, road construction, and road stabilization being the predominant utilization options. Lastly, residues form municipal solid waste incineration attracted more attention recently following the growing number of waste incineration plants globally. The recycling methods of waste incineration residues are the most limited due to its hazardous nature and varying composition, and include, among others, landfill construction, road construction, mine backfilling. In the study, environmental and economic aspects of multiple recycling options of thermal conversion residues generated within a case-study area were studied. The case-study area was South-East Finland. The environmental analysis was performed using an internationally recognized methodology — life cycle assessment. Economic assessment was conducted applying a widely used methodology — cost-benefit analysis. Finally, the results of the analyses were combined to enable easier comparison of the recycling methods. The recycling methods included the use of ash in forest fertilization, road construction, road stabilization, and landfill construction. Ash landfilling was set as a baseline scenario. Quantitative data about the amounts of ash generated and its composition was obtained from companies, their environmental reports, technical reports and other previously published literature. Overall, the amount of ash in the case-study area was 101 700 t. However, the data about 58 400 t of fly ash and 35 100 t of bottom ash and boiler slag were included in the study due to lack of data about leaching of heavy metals in some cases. The recycling methods were modelled according to the scientific studies published previously. Overall, the results of the study indicated that ash utilization for fertilization and neutralization of 17 600 ha of forest was the most economically beneficial method, which resulted in the net present value increase by 58% compared to ash landfilling. Regarding the environmental impact, the use of ash in the construction of 11 km of roads was the most attractive method with decreased environmental impact of 13% compared to ash landfilling. The least preferred method was the use of ash for landfill construction since it only enabled 11% increase of net present value, while inducing additional 1% of negative impact on the environment. Therefore, a following recycling route was proposed in the study. Where possible and legally acceptable, recycle fly and bottom ash for forest fertilization, which has strictest requirements out of all studied methods. If the quality of fly ash is not suitable for forest fertilization, then it should be utilized, first, in paved road construction, second, in road stabilization. Bottom ash not suitable for forest fertilization, as well as boiler slag, should be used in landfill construction. Landfilling should only be practiced when recycling by either of the methods is not possible due to legal requirements or there is not enough demand on the market. Current demand on ash and possible changes in the future were assessed in the study. Currently, the area of forest fertilized in the case-study are is only 451 ha, whereas about 17 600 ha of forest could be fertilized with ash generated in the region. Provided that the average forest fertilizing values in Finland are higher and the area treated with fellings is about 40 000 ha, the amount of ash utilized in forest fertilization could be increased. Regarding road construction, no new projects launched by the Center of Economic Development, Transport and the Environment in the case-study area were identified. A potential application can be found in the construction of private roads. However, no centralized data about such projects is available. The use of ash in stabilization of forest roads is not expected to increased in the future with a current downwards trend in the length of forest roads built. Finally, the use of ash in landfill construction is not a promising option due to the reducing number of landfills in operation in Finland.
Resumo:
Abstract This thesis seeks to answer a number of questions concerning the deficit and debt in Canada. It focuses pri.arily on the federal level of government but with SOBe discussion of provincial governaent policy as well. In ~997, Canada's federal debt caae close ro six hundred billion dollars - $594 billion or 74.4 % of Gross Do.estic Product (GDP) to be exact. The purpose of this theses is threefold: To find out why Canada accu.ulated such a debt, to discover if there is a so-called debt crisis; and to discover if it is possible to preserve Canada's national welfare state given the financial restraints that have been adopted by both federal and provincial governments. Politicians are torn between economist' two contrasting views regarding deficits: Neo-Keynesian and neo-conservative. The neoKeynesian school focuses al1llOst exclusively on the short term stability of the economy and tends to dismiss concerns regarding the level of debt. Neo conservatives focus almost exclusively on the perceived costs of growth in the national debt and are willing to forego any stabilization benefits to ensure that the debt is controlled. These polar view do have one thing in coa.on; both confix-. that deficits influence govermaent policies. Both of these econoBic theories will have far-reaching influences on the federal gover1lJlJent's decision-making process. These economic theories will be discussed throughout this thesis.