12,427 research outputs found
Mosses from the Mascarenes - 7 : a small collection from Rodrigues
No full textFifteen taxa of mosses are reported from the island of Rodrigues. The second African report of Luisierella barbula (Schwaegr.) Steere bridges the Asian and New World disjunctions of this taxon. Three other species are reported new to the Mascarenes, i.e., Calymperes tenerum C.Müller var. tenerum, Fissidens ramulosus Mitten and Weissia edentula Mitten. Three are new to Rodrigues, i.e., Bryum truncorum Bridel, Fissidens sciophyllus Mitten and Vesicularia ayresii (Schimper ex Besch.) Broth
Colheita da azeitona
No full textCom o aproximar do Outono a safra parece estar definida. Contudo, muito poderá
ainda ser feito para valorizar a produção. O método de colheita utilizado, o estado
de maturação da azeitona no momento da apanha e, também, o acondicionamento dos
frutos antes da laboração influenciam significativamente a qualidade do azeite. A agressividade
do método de colheita sobre a árvore e a data de realização podem exercer também
influência sobre a safra do ano seguinte
Deep anisotropic dry etching of silicon microstructures by high-density plasmas
No full textThis thesis deals with the dry etching of deep anisotropic microstructures in monocrystalline silicon by high-density plasmas. High aspect ratio trenches are necessary in the fabrication of sensitive inertial devices such as accellerometers and gyroscopes. The etching of silicon in fluorine-based plasmas is isotropic. To obtain anisotropy the addition of sidewall passivation is necessary. This is achieved with both oxygen passivation at low temperatures and fluorocarbon passivation at room temperature. A quantitative approach was pursued to explain the etching mechanism. The etch results were analysed using the measured plasma species fluxes and the surface composition. Moreover, the transport of the plasma species in narrow anisotropic structures is a fundamental factor determining the etch rate and the profile evolution. The experimental methods such as the etching equipment, plasma diagnostics, surface analysis and sample preparation are described in chapter 2. Three etching processes were investigated: the cryogenic etching process with oxygen passivation at low temperatures, the Bosch process with fluorocarbon passivation at room temperature and the novel triple pulse process that was developed in our laboratory. The polymer deposition mechanism and the characteristic role of the ions are also explained. The cryogenic etching process is discussed in chapter 3. Fluorine radicals, oxygen radicals and ion bombardment are responsible for the three main sub-processes, that is, etching, sidewall passivation and depassivation of the trench bottom, respectively. Etching experiments with an extremely low ion-to-radical flux ratio were used to reveal the etching mechanism. Crystal orientation dependent etching leading to Si(111) crystal facets is observed in a surface kinetics controlled regime. By varying the plasma conditions it is possible to adjust the etching mechanism from fluorine-limited to ion-limited. Controlled etching is obtained because the etching is tuned from aspect ratio dependent in the fluorine-limited domain to aspect ratio independent in the ion-limited domain. The transport of radicals in high aspect ratio trenches is an important limiting factor and was investigated with special structures. The etch results are described by an analytic model that is based on the surface site balance of fluorine and oxygen radicals. The results are further explained with a Monte Carlo simulation model. The Bosch process is clarified in chapter 4. The anisotropy of the etched structures is controlled by balancing the etching and passivation pulse. However, the maximal obtainable aspect ratio is limited by convergence of the trench sidewalls due to excessive passivation. The maximal obtainable aspect ratio increases if the ion-to-radical flux ratio increases. The transport of ions is an important limiting factor in the depassivation of the bottom of the trench. Divergence of the ion beam leads to a reduction of the ion flux, so that the fluorocarbon passivation is insufficiently removed near the base of the sidewalls. The average ion angle was measured and correlated to the maximal obtainable aspect ratio. The Bosch process was improved at the depassivation side with the triple pulse process and at the passivation side with preferential sidewall deposition. The triple pulse process that is described in chapter 5 has the aim to improve the depassivation in deep trenches. The three main sub-processes are decoupled using a separate depassivation pulse directly after the etching and passivation pulses. The fluorocarbon passivation is efficiently removed with low-pressure, high-density, oxygen-based plasmas. The investigated plasma chemistries include O2, CO2 and SO2. The triple pulse process leads to better profile control with a straight trench bottom. However, the maximal obtainable aspect ratio is comparable to the Bosch process because a larger etch depth and a small lateral etch cancel out. The polymer deposition mechanism is treated in chapter 6 with the aim to understand the fluorocarbon passivation in deep trenches. The deposition on plane surfaces and on special structures was investigated to distinguish between the radical-induced and ion-enhanced components. A simple analytical model, which explains the main deposition characteristics, was developed. Preferential sidewall deposition is obtained for higher ion fluxes and higher bias voltages where sputtering plays an important role. In this case no fluorocarbon passivation has to be removed from the bottom of the trench. The trench profile was optimised in the Bosch process by tuning the bias voltage during etching and passivation independently. It resulted in perfectly anisotropic trenches but the maximal obtainable aspect ratio was still limited by a small lateral etch. The characteristic role of the ions in the etching mechanism is explained in chapter 7. Ion-induced etching of both SiC in a SF6-O2 plasma and Si in a Cl2 plasma were investigated. The impact of the ions on the profile evolution can be examined more explicitly because spontaneous chemical reactions are absent for these plasma-material systems. The etching mechanism varies from fluorine-limited to ion-limited depending on the radical-to-ion flux ratio. Microtrenches are observed for an ion-limited etching mechanism. Fluorine-limited SiC etching is aspect ratio dependent in contrast to ion-limited SiC etching, which is aspect ratio independent. The etching of high aspect ratio SiC structures is limited by the positive sidewall taper. This is presumably caused by insufficient removal of the thin fluorocarbon layer on the surface. Si etching in a Cl2 plasma is always aspect ratio independent in contrast to SiC etching because of the low reaction probability. The conclusions and recommendations of this thesis are given in chapter 8.Applied Science
The Role of Mobile Banking in the new Digital Financial Framework: a literature review.
No full textThe impacts of FinTechs (Financial Technology) and digitalization
on the financial sector, and on the banking industry in particular, are more and more consistent, almost disruptive. Progress in mobile device development, with the actual diffusion of smartphones, with a cheaper and widely-spread Internet have led to a growing number of Mobile Banking users all over the world. The present research wants
to analyze the role of Mobile Banking in the present financial digital framework according to the banking perspective. To reach this aim the paper starts with a literature review regarding the significance of Mobile Banking, being difficult to find a relative univocal definition in literature, with no consensus for example in its definition and role in developed and developing countries. Then the paper investigates how FinTech and Digitalization can impact on Banking Industry, considering also the effects of Covid-19 crisis. The work wants also to explore the various channels through which Mobile Money Services affect bank performances. The analysis is able to point out that the actual disruptive changes in mobile financial services and payments can represent also a great opportunity for banks to reduce their marginal costs and to increase their productivity, giving them the possibility to leverage innovative and less costly business models too. The paper in its final part indicates also some critical issues concerning the development of Mobile Banking and, finally, some topics for further researches regarding these subjects
Influência da aplicação de biochar e zeólitos na dinâmica de nitrogênio e de outros nutrientes no solo
No full textMestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáA fertilização nitrogenada tem sido uma boa alternativa para a melhor produtividade na agricultura. No entanto, as aplicações frequentes e generosas conduzem a perdas do nitrogênio (N) principalmente por lixiviação. Os impactos ambientais ocorrem quando há grande quantidade deste nutriente em diferentes ecossistemas, como rios e lagos ou lençóis freáticos. A utilização de condicionadores tem demonstrado a sua utilidade na retenção dos nutrientes no solo reduzindo as perdas para o ambiente. O objetivo deste trabalho foi avaliar o impacto da aplicação de biochar e zeólitos na disponibilidade de N aplicado na forma de ureia para as plantas. Para a realização do trabalho, foi instalado um ensaio em vasos de 3 kg de solo com cinco tratamentos e duas culturas como plantas teste. Os tratamentos foram: Solo (S), Solo + Ureia (SU), Solo + Ureia + Biochar (SUB), Solo + Ureia + Zeólitos (SUZ) e Solo + Ureia + Biochar + Zeólitos (SUBZ). Cada tratamento teve 4 repetições. Em cada vaso foram aplicados nutrientes em quantidades não limitantes para as plantas, como fósforo, potássio e micronutrientes. À exceção do tratamento S, todos os outros tiveram uma quantidade de 360 mg de N por vaso, aplicado na forma de ureia com 45% de N. Os condicionadores (biochar e zeólitos) foram aplicados na quantidade de 15 g/vaso. As plantas utilizadas para testar o efeito dos condicionadores foram alface (Lactuca sativa L.), em dois ciclos vegetativos, e azevém (Lollium multiflorum L.) sujeito a cinco cortes. Após os ciclos da alface e cada corte no azevém procedeu-se à avaliação da matéria seca produzida. No final do ensaio realizaram-se análises ao solo de cada vaso e a biomassa produzida. No solo, os condicionadores tiveram um impacto positivo no teor de matéria orgânica. Os zeólitos aumentaram a disponibilidade de potássio. De um modo geral verificou-se um decréscimo na disponibilidade de nutrientes associado à presença dos condicionadores, mas a dinâmica de imobilização pareceu depender do tipo de íon. As plantas responderam significativamente à aplicação de ureia e a presença dos condicionadores reduziu a produção. Os condicionadores pareceram limitar a quantidade de nutrientes no solo, reduzindo a sua eventual perda por lixiviação.Nitrogen (N) fertilization has been intensively used to increase agricultural productivity. However, frequent and excessive applications lead to N losses from soil. Environmental impacts occur when large amounts of N are lost to water bodies, such as rivers and lakes or even to groundwater. The use of soil conditioners has demonstrated usefulness in retaining nutrients in the soil, reducing losses to the environment. The objective of this study was to evaluate the effect of the application of biochar and zeolites on the availability of N applied as urea to plants. An experiment was performed in pots of 3 kg of soil with five treatments and two crops as plant test. The treatments were: Soil (S), Soil + Urea (SU), Soil + Urea + Biochar (SUB), Soil + Urea + Zeolites (SUZ) and Soil + Urea + Biochar + Zeolites (SUBZ). Each treatment had 4 replications. Phosphorus, potassium, and micronutrients were applied to each pot in non-limiting quantities. With the exception of S treatment, all others received an amount of 360 mg N per pot, applied in the urea form (45% N). The conditioners (biochar and zeolites) were applied in the amount of 15 g per pot. The plants used to test the effect of the soil conditioners were lettuce (Lactuca sativa L.), two growing seasons, and ryegrass (Lollium multiflorum L.) subjected to five cuts. After each lettuce growing cycle and each cut of ryegrass, the dry matter yield was evaluated. At the end of the experiment, analyses were performed on the soil of each pot and on produced biomass. In the soil, the conditioners had a positive impact on the organic matter content. Zeolites increased potassium availability. In general, it was observed a decrease in soil nutrient availability associated with the presence of soil conditioners, but the dynamics of immobilization seemed depend on the type of ion. The plants responded significantly to the urea application and the presence of conditioners reduced dry matter yield. The soil conditioners seemed to limit the amount of nutrients in the soil, which potentially may reduce nutrient loss by leaching
Influência da aplicação de biochar e zeólitos na dinâmica de nitrogênio e de outros nutrientes no solo
No full textMestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáA fertilização nitrogenada tem sido uma boa alternativa para a melhor produtividade na agricultura. No entanto, as aplicações frequentes e generosas conduzem a perdas do nitrogênio (N) principalmente por lixiviação. Os impactos ambientais ocorrem quando há grande quantidade deste nutriente em diferentes ecossistemas, como rios e lagos ou lençóis freáticos. A utilização de condicionadores tem demonstrado a sua utilidade na retenção dos nutrientes no solo reduzindo as perdas para o ambiente. O objetivo deste trabalho foi avaliar o impacto da aplicação de biochar e zeólitos na disponibilidade de N aplicado na forma de ureia para as plantas. Para a realização do trabalho, foi instalado um ensaio em vasos de 3 kg de solo com cinco tratamentos e duas culturas como plantas teste. Os tratamentos foram: Solo (S), Solo + Ureia (SU), Solo + Ureia + Biochar (SUB), Solo + Ureia + Zeólitos (SUZ) e Solo + Ureia + Biochar + Zeólitos (SUBZ). Cada tratamento teve 4 repetições. Em cada vaso foram aplicados nutrientes em quantidades não limitantes para as plantas, como fósforo, potássio e micronutrientes. À exceção do tratamento S, todos os outros tiveram uma quantidade de 360 mg de N por vaso, aplicado na forma de ureia com 45% de N. Os condicionadores (biochar e zeólitos) foram aplicados na quantidade de 15 g/vaso. As plantas utilizadas para testar o efeito dos condicionadores foram alface (Lactuca sativa L.), em dois ciclos vegetativos, e azevém (Lollium multiflorum L.) sujeito a cinco cortes. Após os ciclos da alface e cada corte no azevém procedeu-se à avaliação da matéria seca produzida. No final do ensaio realizaram-se análises ao solo de cada vaso e a biomassa produzida. No solo, os condicionadores tiveram um impacto positivo no teor de matéria orgânica. Os zeólitos aumentaram a disponibilidade de potássio. De um modo geral verificou-se um decréscimo na disponibilidade de nutrientes associado à presença dos condicionadores, mas a dinâmica de imobilização pareceu depender do tipo de íon. As plantas responderam significativamente à aplicação de ureia e a presença dos condicionadores reduziu a produção. Os condicionadores pareceram limitar a quantidade de nutrientes no solo, reduzindo a sua eventual perda por lixiviação.Nitrogen (N) fertilization has been intensively used to increase agricultural productivity. However, frequent and excessive applications lead to N losses from soil. Environmental impacts occur when large amounts of N are lost to water bodies, such as rivers and lakes or even to groundwater. The use of soil conditioners has demonstrated usefulness in retaining nutrients in the soil, reducing losses to the environment. The objective of this study was to evaluate the effect of the application of biochar and zeolites on the availability of N applied as urea to plants. An experiment was performed in pots of 3 kg of soil with five treatments and two crops as plant test. The treatments were: Soil (S), Soil + Urea (SU), Soil + Urea + Biochar (SUB), Soil + Urea + Zeolites (SUZ) and Soil + Urea + Biochar + Zeolites (SUBZ). Each treatment had 4 replications. Phosphorus, potassium, and micronutrients were applied to each pot in non-limiting quantities. With the exception of S treatment, all others received an amount of 360 mg N per pot, applied in the urea form (45% N). The conditioners (biochar and zeolites) were applied in the amount of 15 g per pot. The plants used to test the effect of the soil conditioners were lettuce (Lactuca sativa L.), two growing seasons, and ryegrass (Lollium multiflorum L.) subjected to five cuts. After each lettuce growing cycle and each cut of ryegrass, the dry matter yield was evaluated. At the end of the experiment, analyses were performed on the soil of each pot and on produced biomass. In the soil, the conditioners had a positive impact on the organic matter content. Zeolites increased potassium availability. In general, it was observed a decrease in soil nutrient availability associated with the presence of soil conditioners, but the dynamics of immobilization seemed depend on the type of ion. The plants responded significantly to the urea application and the presence of conditioners reduced dry matter yield. The soil conditioners seemed to limit the amount of nutrients in the soil, which potentially may reduce nutrient loss by leaching
Assessment of Models for Near Wall Behavior and Swirling Flows in Nuclear Reactor Sub-system Simulations
No full textAccurate simulation of turbulence remains one of the most challenging problems in nuclear reactor analysis and design. Due to limitations in computing resources, Reynolds averaged Navier Stokes models (RANS) continue to play an important role in reactor simulations. The Consortium for advanced simulations of light water reactors (CASL) is a Department of Energy technology hub that is investing in research and developmentof a state-of-the-art computational fluid dynamics capabilityto meet the challenges of turbulent simulation of nuclear reactors. In this presentation, we assess several RANS eddy viscosity models appropriate for single-phase incompressible turbulent flows. Specifically, we compare the single equation Splalart-Allmaras to several variations of the model. The assessment takes into consideration elements of full system reactor cores such as complex geometries, heterogeneous meshes, swirling flow, near wall flow behavior, heat transfer and robustness issues. The goal of this strategically oriented assessment is to provide an accurate and robust turbulent simulation capability for the CASL community. Metrics of performance will be constructed by comparing different models on a strategically chosen set of problems that represent reactor core sub-systems
O zarubežnoj dejatel'nosti professora M.A. Kumaxova
No full textOn professor M.A. Kumakhov's work and research abroad (in Russian)
Professor Mukhadin A. Kumakhov and the author collaborated in the area of Northwest Caucasian languages under a period from 1991 to 2008. The fruitful collaboration at Lund and Malmö universities resulted in three joint monographs and a number of articles, which is outlined in the article. Mukhadin A. Kumakhov became Honorary Doctor of the Philosophical Faculty of Lund University in 1998
Bringing clouds into our lab!: The influence of turbulence on early stage rain droplets
No full textWe are investigating a droplet-laden flow in an air-filled turbulence chamber, forced by speaker-driven air jets. The speakers are running in a random manner; yet they allow us to control and define the statistics of the turbulence. We study the motion of droplets with tunable size in a turbulent flow, mimicking the early stages of raindrop formation. 3D Particle Tracking Velocimetry (PTV) is chosen as the experimental method to track the droplets and collect data for statistical analysis. Thereby it is possible to study the spatial distribution of the droplets in turbulence using the so-called Radial Distribution Function (RDF), a statistical measure to quantify the clustering of particles. Additionally, this technique allows us to measure velocity statistics of the droplets and the influence of the turbulence on droplet trajectories, both individually and collectively. In this contribution, we will present velocity statistics of the droplets and quantify their clustering using the RDF for different turbulence conditions
The Story about the constructed SARS COV-2 Virus - A Review of three Research Groups
No full textAbstract
A literature research on synthetic recombinant SARS Coronavirus was made to answer two questions. Is the SARS CoV-2 virus designed in a laboratory? And why has the SARS CoV-2 such a high mutation rate? A total of 12 research articles, 2 reviews and 10 experimental studies were attributed to three Research Groups, the Wadsworth Center New York, the Vanderbilt Medical Center, and the Chapel Hill North Carolina. The research papers were published between 1991 and 2014. All 12 research papers reported the successful construction of recombinant SARS Coronaviruses based on RNA reverse genetic and molecular techniques. The Research group from the Medical Center at Vanderbilt University proved how an engineered SARS Coronavirus with an impaired Exonuclease resulted in a progeny virus with high mutation rate. Furthermore, the review showed that a zoonotic-human transmission was just possible with specific genetic manipulations at the SARS CoV virus genome through selection of virus species for recombination, and targeted manipulation at non-structural virus domains. But importantly, the studies showed that a SARS Coronavirus cross-species infection such as between zoonotic and humans or between different animal species without the exchange of the virus spike protein domain with the host-specific receptor-binding domain (RBD) and additional point mutations was not possible. Therefore, the SARS CoV-2 was deliberately constructed to overcome the receptor limiting factor for animal-human infection. Interestingly, the review revealed that the study purpose of constructed recombinant SARS CoV changed from the scientific research point of view to vaccine production and development. Competing interests for all reviewed studies by grants from private investors such as the Gates Foundation and vaccine production companies were part of the discussion. Keywords: SARS CoV-2, Covid19, Spike protein, gene sequencing, Vanderbilt University, University North Carolina, Wadsworth Research Center, New York Health Department, Coronavirus, Bill & Melinda Gates Foundation, WHO, Pfizer, Merck, Novartis, AlphaVaxThe author declares no competing interests.
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