O desgaste de máquinas e seus componentes têm grande influência econômica em diversos setores da indústria. Diante dessa situação, tem sido feitos estudos visando desenvolver novos materiais e revestimentos que apresentem maior resistência ao desgaste. O revestimento é um dos métodos mais utilizados quando se procura garantir a uma superfície alguma propriedade mecânica que não é intrínseca ao metal base. O objetivo deste trabalho é realizar um estudo comparativo de ligas de diferentes composições químicas, através do desenvolvimento de um consumível para soldagem manual ao arco elétrico a ser aplicado especialmente para o recobrimento de superfícies submetidas ao desgaste abrasivo. Os eletrodos desenvolvidos foram compostos pela combinação de cromo-carbono e tungstênio-carbono misturados em um revestimento base com rutilo-carbonato de cálcio-fluorita, resultando em eletrodos revestidos com sete diferentes composições. A comparação e avaliação da resistência à abrasão foi feita com base nos dados obtidos no ensaio de desgaste abrasivo, segundo a norma ASTM G65-91, e também baseada nos resultados da composição química, microestrutura e análise microestrutural dos revestimentos. Os resultados mostraram que os depósitos com maior resistência ao desgaste abrasivo foram obtidos com eletrodos com as composições contendo carbono e 7% de tungstênio e carbono e 1,5% de cromo. Esses mesmos depósitos foram os que apresentaram valores mais elevados de microdureza, e em sua microestrutura pode-se perceber a formação de maior quantidade de carbonetos. / The wear in machines and equipments is one of the main sources of economic losses. Nowadays many studies have been conducted to develop new materials and coverages to produce wear resistance. The hardfacing is one of most common methods to produce a deposit having properties not intrinsic to that of the base material. The main objective of this work is to study the viability of using different alloys compositions to produce covered electrodes for shielded metal arc welding (SMAW) resistant to abrasive wear. The covered electrodes were produced adding chromiumcarbon and tungsten-carbon to rutile-calcium carbide-fluorite base. Comparison and evaluation of wear resistance of the developed electrodes was based in ASTM G65-91 wear tests, deposit chemical compositions and the resultant microstructures. The results shown that electrodes containing additions of C-W 7 % and C-Cr 1.5 % produced best performance of wear test deposits. These compositions produced deposits containing the higher amounts of carbides and exhibit higher hardness values.

O desgaste de máquinas e seus componentes têm grande influência econômica em diversos setores da indústria. Diante dessa situação, tem sido feitos estudos visando desenvolver novos materiais e revestimentos que apresentem maior resistência ao desgaste. O revestimento é um dos métodos mais utilizados quando se procura garantir a uma superfície alguma propriedade mecânica que não é intrínseca ao metal base. O objetivo deste trabalho é realizar um estudo comparativo de ligas de diferentes composições químicas, através do desenvolvimento de um consumível para soldagem manual ao arco elétrico a ser aplicado especialmente para o recobrimento de superfícies submetidas ao desgaste abrasivo. Os eletrodos desenvolvidos foram compostos pela combinação de cromo-carbono e tungstênio-carbono misturados em um revestimento base com rutilo-carbonato de cálcio-fluorita, resultando em eletrodos revestidos com sete diferentes composições. A comparação e avaliação da resistência à abrasão foi feita com base nos dados obtidos no ensaio de desgaste abrasivo, segundo a norma ASTM G65-91, e também baseada nos resultados da composição química, microestrutura e análise microestrutural dos revestimentos. Os resultados mostraram que os depósitos com maior resistência ao desgaste abrasivo foram obtidos com eletrodos com as composições contendo carbono e 7% de tungstênio e carbono e 1,5% de cromo. Esses mesmos depósitos foram os que apresentaram valores mais elevados de microdureza, e em sua microestrutura pode-se perceber a formação de maior quantidade de carbonetos. / The wear in machines and equipments is one of the main sources of economic losses. Nowadays many studies have been conducted to develop new materials and coverages to produce wear resistance. The hardfacing is one of most common methods to produce a deposit having properties not intrinsic to that of the base material. The main objective of this work is to study the viability of using different alloys compositions to produce covered electrodes for shielded metal arc welding (SMAW) resistant to abrasive wear. The covered electrodes were produced adding chromiumcarbon and tungsten-carbon to rutile-calcium carbide-fluorite base. Comparison and evaluation of wear resistance of the developed electrodes was based in ASTM G65-91 wear tests, deposit chemical compositions and the resultant microstructures. The results shown that electrodes containing additions of C-W 7 % and C-Cr 1.5 % produced best performance of wear test deposits. These compositions produced deposits containing the higher amounts of carbides and exhibit higher hardness values.

Ground penetrating radar (GPR) is widely used to identify locations of sinkholes in covered karst terrain in Florida. Some sinkholes serve as hydraulic conduits between the surficial and underlying aquifers. Their role is critical in determining the surficial aquifer response to pumping in deeper aquifers. Improved methods for discriminating between hydraulically active sinkholes and plugged sinkholes could help regional water management. In the covered karst of west-central Florida a clay-rich weathering horizon forms over the limestone. The clay-rich layer is in turn overlain by surficial sands. Ground penetrating radar profiles typically show a strong reflector from the top of clay-rich horizon as well as internal layering within sands. Active sinkholes are expected to have sandy conduits that broach the clay layer, and perhaps layering in the overlying sand indicative of ongoing subsidence. Three dimensional simulations of GPR profiles over sinkhole with and without conduits were run with the finite-difference time-domain (FDTD) program GPRMAX. Results from the synthetic surveys were then processed with standard techniques, including migration. The modeling confirms that conduits appear in GPR records primarily as gaps in the return from the clay layer. The modeling also shows that non-traditional survey geometries (varying antenna spacing and orientation) are unlikely to recover more information than traditional proximal transmitter-receiver separation. Also examined are GPR profiles and 3D grids over a set of active and inactive sinkholes in Tampa, Florida. Results from these surveys showed decent structural recovery of a small sinkhole similar in structure to that of the modeled ones. Indications of active subsidence and possible conduit structure were apparent from this data. Finally, the dense surveys served as a benchmark to compare interpretations taken with the same surveys at lower spatial resolutions and profiles with 2D-only processing methods in order to understand errors in analysis and interpretation that are possible from 2D surveys. Two-dimensional surveys, 2D processed and migrated, showed some similarity to the 3D results previously mentioned but contained more complexities and artifacts, which led to poorer interpretation ability.

Antarctic debris-covered glaciers are potential archives of long-term climate change. However, the geomorphic response of these systems to climate forcing is not well understood. To address this concern, I conducted a series of field-based and numerical modeling studies in the McMurdo Dry Valleys of Antarctica (MDV), with a focus on Mullins and Friedman glaciers. I used data and results from geophysical surveys, ice-core collection and analysis, geomorphic mapping, micro-meteorological stations, and numerical-process models to (1) determine the precise origin and distribution of englacial and supraglacial debris within these buried-ice systems, (2) quantify the fundamental processes and feedbacks that govern interactions among englacial and supraglacial debris, (3) establish a process-based model to quantify the inventory of cosmogenic nuclides within englacial and supraglacial debris, and (4) isolate the governing relationships between the evolution of englacial /supraglacial debris and regional climate forcing. Results from 93 field excavations, 21 ice cores, and 24 km of ground-penetrating radar data show that Mullins and Friedman glaciers contain vast areas of clean glacier ice interspersed with inclined layers of concentrated debris. The similarity in the pattern of englacial debris bands across both glaciers, along with model results that call for negligible basal entrainment, is best explained by episodic environmental change at valley headwalls. To constrain better the timing of debris-band formation, I developed a modeling framework that tracks the accumulation of cosmogenic 3He in englacial and supraglacial debris. Results imply that ice within Mullins Glacier increases in age non-linearly from 12 ka to ~220 ka in areas of active flow (up to >> 1.6 Ma in areas of slow-moving-to-stagnant ice) and that englacial debris bands originate with a periodicity of ~41 ka. Modeling studies suggest that debris bands originate in synchronicity with changes in obliquity-paced, total integrated summer insolation. The implication is that the englacial structure and surface morphology of some cold-based, debris-covered glaciers can preserve high-resolution climate archives that exceed the typical resolution of Antarctic terrestrial deposits and moraine records.

Wheat is the most important cereal crop in the world. It is the principal staple food in Russia, United States, China, Canada, India and a number of other countries. Covered smut is one of the most serious disease of wheat all over the world. According to Woolman and Humphrey (82) it was known from very early times and is referred to by Theoprastus and other early Greek Roman writers.

Målet med denna rapport är att undersöka vad bolånefonder är, och hur de skiljer sig mot säkerställda obligationer. Avgränsningar görs till att endast ta upp svenska aktörer, och framförallt bostadskreditinstitutet Stabelo. Arbetet baseras på en kvalitativ metod där skillnader i säkerhet för bolånen, finansieringsstruktur, risk, avkastning samt tillsyn, kapitalkrav och riskhantering analyseras genom att bland annat studera bankers och bostadskreditinstitutet Stabelos belåningsgrad och avkastningskurvor. Skillnaderna mellan de två finansieringsformerna är, sett till vad de åstadkommer, inte stora. En slutsats är däremot att det finns en väsentlig skillnad i hur finansieringssätten är strukturerade, och att denna skillnad kan attrahera olika investerare. / The goal with this bachelor thesis is to examine what an alternative investment fund is, and how it differs from covered bonds. The report is limited to only covering Swedish market participants, and therein especially the alternative investment fund by Stabelo. The report takes a qualitative approach, where differences in financing structure, risk, yield as well as governance, capital requirement and risk management are being analysed, through studying the yield and underlying loan-to-value of banks and Stabelo. The differences between the two forms of financing, in the perspective of what they accomplish, are not immense. However, a major conclusion is that the difference lies in the way they are structured, and that this difference might suits different investors.

Algae extracts are used as cosmetic products and used as additives in specific foods because of their antioxidant activity. Reactive oxygen species (ROS) such as hydrogen peroxide and superoxide radicals are toxic on the skin and can be scavenged by antioxidants, which are abundant in microalgae. Antioxidant substances protect the skin against external factors such as ultraviolet light (UV). Many creams that are concerned with treating the skin have antioxidant molecules. Researchers are performing many studies to achieve natural and non-chemical skin maintenance for the skin. Conducting in vivo studies to analyze the antioxidant potential of extracts on skin needs ethical permission to recruit a specific number of people. In this study, pig ear skin was used with the help of a skin-membrane-covered oxygen electrode (SCOE) to analyze the antioxidant effect of an extract from the microalgae Chlamydomonas reinhardtii. A study proved that this method was effective in measuring other antioxidants. Hydroquinone was used as a control to see if the system worked correctly. Hydroquinone showed that it could penetrate the skin and give antioxidant activity. When the algae extract was used, the same effect as for hydroquinone could not be detected. With a 2,2-diphenylpicrylhydrazyl (DPPH) assay, the algae extract was analyzed for its antioxidant capacity, and the assay revealed a positive antioxidant effect of the extract. The spectrophotometric measurement of the amount of bioactive antioxidant molecules in the extract in different solutions suggested that the one resuspended in ethanol presented a higher amount of carotenoids and chlorophylls than the extract resuspended in an aqueous buffer. Additional research will be needed to characterize the antioxidant potential of the extract from the microalgae Chlamydomonas reinhardtii.

Yes / Ice cover formed on an alluvial channel can significantly alter the flow characteristics, such as the vertical distributions of streamwise velocity and shear stress, and hence the water and sediment transport process. The vertical profile of the suspended sediment concentration in the ice-covered alluvial channels with steady uniform flows is investigated in this study. To calculate the suspended sediment concentration, we are based on the Schmidt O’Brien equation and deduce an analytical model that employs an existing eddy viscosity model and a modified formula of the sediment fall velocity considering the common effects of the upper and lower boundaries. The proposed analytical model is then validated by using available experimental data reported in the literature. The predicted accuracy of the proposed model is evaluated through error statistics by comparing to previous modeled results. The relative concentration profiles of the suspended sediment are subsequently simulated by applying the validated analytical model with different characteristic parameters. Results show that the relative concentration decreases with the increase of both the ice cover roughness and the sediment fall velocity. The uniformity of the relative concentration distribution is closely related to the value of the proportionality parameter σ, revealing the physical mechanism that the more prominent the turbulent diffusion effect is, the more uniform the relative concentration profile is. / This work was supported by the National Natural Science Foundation of China (grant 604 numbers 52020105006 and 11872285) and the Open Funding of State Key Laboratory of Water Resources and Hydropower Engineering Science (WRHES), Wuhan University (Project number 2018HLG01).

Thesis (M.M. (Finance & Investment))--University of the Witwatersrand, Faculty of Commerce, Law and Management, Graduate School of Business Administration, 2014. / The use of a Covered Call strategy has long been favoured by investors the world over for its potential to enhance yield in a long-only equity portfolio. There already exists a wealth of research examining the risk and return features and theories of this strategy. This paper aims to contribute to this debate by conducting research that is specific to the South African equity market and considered from the perspective of a retail investor, particularly by tracking the negative friction induced by transaction costs. It also seeks to answer the question of which Covered Call strategies provide the best risk-adjusted returns by pricing various expiry range and moneyness combinations over differing market trend phases during a 13-year period of trade on the JSE.

The Patient Protection and Affordability Act of 2010 (PPACA) addressed the access to healthcare in the United States. One of the problems of this healthcare access was rooted in disproportionally lower access among minority populations. The purpose of this quantitative study, guided by the consumer behavior theory, was to examine the association between race/ethnicity and enrollment within the Covered California-?¢ (CoveredCA) Insurance Exchange. A cross-sectional study design was used to investigate the association between race/ethnicity and the use of Covered CA health benefit exchange. Logistic regression analysis was used to examine the relationship between enrollment and race/ethnicity, having adjusted for covariates of age, gender, and literacy. The results revealed that, while all other race/ethnicity groups were less likely to purchase Bronze level versus Silver and above coverage compared to the Hispanic race/ethnicity, Asians (OR =1.16, 95% CI: 1.11, 1.20) and Whites (OR = 1.12, 95% CI: 1.02, 1.14) were more likely to purchase Bronze level versus Silver and above coverage compared to the Hispanic group. Chi-square test results indicated a statistically significant difference in the proportion of individuals selecting the Bronze level coverage compared to the Silver and above among the various race/ethnicity groups ï?£2 (13, N= 763,531), 1922.083, p < 0.0001. The Hispanic race/ethnicity was more likely to enroll in the Bronze versus Silver and above compared to other race/ethnicities. The results of this study may contribute to positive social change by informing policy that besides income and age, race/ethnicity is an important determinant of the likelihood of enrollment in the Covered CA health exchange.