Academic literature on the topic 'NATURAL SOLUTION'

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-09-29T13:05:00Z No. of bitstreams: 1 Mariovane Sabino Donini - 2017.pdf: 4347435 bytes, checksum: b83edb6c2d0b7868757722dc435be9fa (MD5)<br>Approved for entry into archive by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2017-09-29T16:25:43Z (GMT) No. of bitstreams: 1 Mariovane Sabino Donini - 2017.pdf: 4347435 bytes, checksum: b83edb6c2d0b7868757722dc435be9fa (MD5)<br>Made available in DSpace on 2017-09-29T16:25:43Z (GMT). No. of bitstreams: 1 Mariovane Sabino Donini - 2017.pdf: 4347435 bytes, checksum: b83edb6c2d0b7868757722dc435be9fa (MD5) Previous issue date: 2017<br>In the present work, vaporization and combustion of an isolated fuel droplet at diferente ambient temperatures are examined numerically in order to analyze the effect of buoyancy force on the flame. Generally, fuel droplets in combustion devices are so small that the influence of buoyancy force on vaporization and combustion of droplets is negligible. On the other hand, fuel droplets in experimental devices are affected by the buoyancy force due to their diameters being around or more than 1 mm. To reduce the buoyancy effects, expensive experimental studies are performed in microgravity ambient (drop-tower or out of space). In normal-gravity conditions, the buoyancy force is induced by temperature gradient on ambient atmosphere. The buoyancy is positive in regions of hot gases and negative in regions of cold gases compared with the ambient atmosphere gas. Hot gases move upward and cold gases downward. Playing with the positive buoyancy force of hot gases around the flame and with the negative (cold) buoyancy force of cold gases around the droplet via ambient atmosphere temperature, it is possible to modify the flame shape. In the numerical simulations, incompressible Navier–Stokes equations along with mixture fraction and excess enthalpy conservation equations are solved using a finite volume technique with a uniform structured grid. An artificial compressibility method was applied to reach steady state solutions. The numerical predictions have been compared with analytical results for a zero gravity condition, showing good agreement. For normal gravity condition the numerical results showed that when the ambient temperature increases, the velocity gradient and buoyancy source term decreases. Despite that, the flame increased in all directions. The results have also shown that increasing the ambient temperature, decreases the temperature gradient in the flame, which ends up affecting the flame position.<br>No presente trabalho, a vaporização e a combustão de uma gota de combustível isolada a diferentes temperaturas ambiente são examinadas numericamente para analisar o efeito da força de flutuação na chama. Geralmente, as gotículas de combustível em dispositivos de combustão são tão pequenas que a influência da força de flutuação na vaporização e na combustão de gotículas é insignificante. Por outro lado, as gotículas de combustível em dispositivos experimentais são afetadas pela força de flutuabilidade devido ao seu diâmetro em torno de ou mais de 1 mm. Para reduzir os efeitos de flutuabilidade, estudos experimentais caros são realizados em ambiente de microgravidade (drop-tower ou fora do espaço). Em condições de gravidade normal, a força de flutuação é induzida por gradiente de temperatura na atmosfera ambiente. A flutuabilidade é positiva em regiões de gases quentes e negativas em regiões de gases frios em comparação com o gás atmosférico ambiente. Os gases quentes movem-se para cima e os gases frios para baixo. Jogando com a força de flutuação positiva dos gases quentes ao redor da chama e com a força de flutuação negativa (fria) dos gases frios ao redor da gota através da temperatura da atmosfera ambiente, é possível modificar a forma da chama. Nas simulações numéricas, as equações de Navier-Stokes incompressíveis juntamente com a fração de mistura e as equações de conservação de entalpia em excesso são resolvidas usando uma técnica de volume finito com uma grade estruturada uniforme. Foi aplicado um método de compressibilidade artificial para alcançar soluções de estado estacionário. As previsões numéricas foram comparadas com resultados analíticos para uma condição de gravidade zero, mostrando boa concordância. Para a condição de gravidade normal, os resultados numéricos mostraram que, quando a temperatura ambiente aumenta, o gradiente de velocidade e o termo da fonte de flutuação diminuem. Apesar disso, a chama aumentou em todas as direções. Os resultados também mostraram que aumentar a temperatura ambiente, diminui o gradiente de temperatura na chama, o que acaba afetando a posição da chama.

This Thesis comprises of experimental and the theoretical work done on the analysis of hydrocarbon solubility in amine solutions used for natural gas processing. The objective of this study is the solubility of hydrocarbons in different Amine solutions and the comparison of the results obtained, in order to understand their behaviour in applications related to Natural Gas processing. From solubility knowledge indeed several informations of interest could be obtained such as: i) quantification of possible losses of hydrocarbons during amine treatment ii) evaluation of the amount of these components reaching the stripper and iii) determination of the additional work to be done for purification of the amine solutions after the absorber. Data for the solubility of the different hydrocarbon and Amines are indeed important for proper modelling of absorption columns and the strippers. The peculiarity of the study is that in addition to the analysis of solubility on pure and mixed amine solution also the solubility of loaded amine solutions will be considered, i.e. Amine solution mixed with acid gas like CO2 and/or H2S. Indeed, while there had been previous measurements made on this project, but they were basically for the non-loaded amine solution, giving therefore only partial information on this topic. This experiment is carried out at the laboratories of the group of Chemical Engineering at Aalto School of Chemical Technology and written at the University of Bologna Italy. The chief apparatus for this study among others are BBQ apparatus with a capacity of 30 vials and GC Agilent 7890 B. The following Hydrocarbons were used: Benzene, Ethylbenzene, Toluene, Hexane, Cyclohexane and 2,2,4-Trimethylpentane and the following amines solutions: Diglycolamine (DGA), N-methyl-diethanolamine(MDEA), Monoethanolamine(MEA), Di-Ethanolamine(DEA), and Piperazine. Tests were carried out at (define T and P) and at H2S and CO2 loading level ranging from about 0.15 to 0.45

Peptoids are synthetic mimics of naturally-occurring peptides (the natural building blocks of proteins). These interesting building blocks are more resistant to temperature, pH and solvent denaturation, and possess a more exible backbone compared to their peptide counterparts. As a result, peptoids are emerging as promising biomimetic materials for a range of applications. Despite this potential, very little is known about the intermolecular interactions which determine their stability and solubility, including hydrogen-bonding, hydrophobic interactions and hydration properties, as well the structural properties of the individual imino acid blocks that make them. This thesis presents neutron diffraction experiments coupled with isotopic substitution and computational modelling to complete a structural study on a model imino acid in aqueous solution. The focus here has been on glutamine, a molecule that is capable of forming multiple hydrogen bonds and is thought to self-assemble through preferential side-chain hydrogen bond interactions, making it an interesting model system. Furthermore, glutamine is important in many biochemical processes and its presence has been associated with a number of neurodegenerative diseases. By probing the structural properties of the model system in aqueous solution and of its amino acid equivalent, L-glutamine, it has been possible to uncover details of important intermolecular interactions that govern the properties of these biomolecules. The interactions of the model imino acid have also been observed with respect to temperature and concentration and compared to a naturally-occurring imino acid, sarcosine, to determine the impact of side chain on imino acid interactions. This work also serves as a reference for completing structural studies on such biomolecules, covering methodological benefits and limitations. This is the necessary first step in building a framework to understand the self-assembly and driving forces in more complex peptoid and peptide structures and serves as a reference for completing neutron studies on natural and synthetic biomolecules.

This study proposes an accuracy comparison of two of the best performing machine learning algorithms in natural language processing, the Bayesian Network and the Long Short-Term Memory (LSTM) Recurrent Neural Network, in detecting Alzheimer’s disease symptoms in conversation transcripts. Because of the current global rise of life expectancy, the number of seniors affected by Alzheimer’s disease worldwide is increasing each year. Early detection is important to ensure that affected seniors take measures to relieve symptoms when possible or prepare plans before further cognitive decline occurs. Literature shows that natural language processing can be a valid tool for early diagnosis of the disease. This study found that mild dementia and possible Alzheimer’s can be detected in conversation transcripts with promising results, and that the LSTM is particularly accurate in said detection, reaching an accuracy of 86.5% on the chosen dataset. The Bayesian Network classified with an accuracy of 72.1%. The study confirms the effectiveness of a natural language processing approach to detecting Alzheimer’s disease.

Lipid peroxidation has been implicated in the onset and progression of many degenerative diseases, including cardiovascular disease, Alzheimer’s disease and cancer. Accordingly, for more than 50 years, considerable effort has been devoted to the design of synthetic compounds or the discovery of natural products that can slow lipid peroxidation. Despite the enormous investments made to date, no clear antioxidant strategies have emerged for the treatment and/or prevention of degenerative disease. We argue that this is because of a lack of fundamental understanding of the chemical reactivity of these compounds in relevant contexts. Herein, we describe studies of our optimized synthetic radical-trapping antioxidant (RTA) – the tetrahydronaphthyridinols (THNs). We first present the synthesis of a series of THN analogs of α-tocopherol (Nature’s premier lipid-soluble radical-trapping antioxidant) with varying sidechain substitution and then demonstrate how systematic changes in the lipophilicity of these potent antioxidants impact their peroxyl radical-trapping activities in lipid bilayers and mammalian cell culture. Their regenerability by water-soluble reductants in lipid bilayers, binding to human tocopherol transport protein (hTTP), and cytotoxicity were also evaluated to provide insight on whether this type of antioxidant can be potentially pushed toward animal studies. We also describe analogous studies of natural products such as the garlic-derived thiosulfinate allicin and the grape-derived polyphenol resveratrol. These compounds have attracted significant attention in the past 20 years due to their purported health benefits, which are often ascribed to their purported radical-trapping activities. To date, systematic studies on their radical-trapping activities in solution, lipid bilayers and mammalian cells have been lacking. We have determined that allicin and petivericin, while effective RTAs in solution, are not so in lipid bilayers. Moreover, the compounds are not antioxidants in cell culture, but instead kill the cells. Similarly, resveratrol and its dimers pallidol and quadrangularin A, are found to be inefficient RTAs in lipid bilayers. Our studies to date rather suggest that they autoxidize readily to produce hydrogen peroxide, which may induce expression of phase 2 antioxidant enzymes, affording cytoprotection. Our insights underscore the need for systematic studies of antioxidant activity in multiple contexts.

<p>The main goal for a packaging is to protect the product inside. Typical packaging nowadays is made of layers of paper and barriers consisting of plastics or aluminum foil. A problem with the barrier used today is the environmental thinking. Xylophane® is an environmental friendly and biodegradable alternative to the current barrier material used in packaging. It consists of the natural carbohydrate xylan and additives. Xylophane® is an efficient barrier to oxygen, grease and aroma and can prolong the shelf life of sensitive food.</p><p>The raw material xylan is water soluble and Xylophane® can be coated on paper, board and plastics without using other solvents. A problem with the drying process is the amount of energy needed and the consumption needs to be decreased. Also, the drying capacity of the equipment to be used is often limited and the amount of water to be dried off is critical for the success of the coating process. By increasing the dry content of Xylophane® without increasing the viscosity too much, the drying process can be more effective. In this thesis, studies were made of using a filler as an additive to increase the dry content without destroying the barrier properties.</p><p>With an experimental design, a suitable relationship between the ingredients xylan (X), plasticizer (P) and filler (F) was found. Xylan is the main component and is needed to get a good oxygen barrier. The plasticizer decreases the oxygen barrier properties but is needed to make the material more flexible. The filler is positive for the barrier properties. The chosen composition was X:P = 7:3 and X:F = 1:1. Some extra experiments were made to find a reasonable value of the dry content. Dry contents around 18 % work well with temperatures at and above 45°C, but to manage to perform coating at room temperature the dry content needs to be lower.</p>