Exploratory research analysis on emissions generated in internal combustion engines

It is common knowledge that internal combustion engines have the function of transforming thermal energy into useful mechanical work. During the combustion process of the fuel and air mixture (heat generation) a quantity of gases are produced and released into the environment by the exhaust system of these engines. When these machines were invented, their creators might not have had the notion that the generated gases would be aggressors to nature. The constant population growth, the increasing demand for the use of these engines and observations of the impact in nature, among them the health and greenhouse effects, evidenced mainly from the end of the last century, led scientists to study the problem related to gaseous emissions from these machines. The present work aims to study and evaluate the emissions of internal combustion engines, their consequences both to the human health and to the environment, the evolution of government legislation and also the control mechanisms implemented to reduce these pollutants. The applied methodology is a qualitative and exploratory study of bibliographic character of theoretical and experimental works that were presented in master's dissertations, doctoral theses, scientific articles and websites of companies specialized in the subject

Numerical study of inflow turbulence distortion and noise for airfoils

In this work, the interaction of grid-generated turbulence with airfoils of different thicknesses, namely, a National Advisory Committee for Aeronautics (NACA) 0008 and a NACA 0018, is investigated, leading to a deeper understanding of the influence of the airfoil geometry on the near-field flow and on the far-field pressure fluctuations. Experimentally validated lattice-Boltzmann simulations are used to analyze the flow properties in the leading-edge (LE) vicinity. The analysis of the velocity fluctuations near the LE shows that momentum is transferred from the streamwise to the transverse velocity for the NACA 0008 airfoil interacting with a large turbulence length scale. This mechanism changes with the increase in the airfoil thickness because the inflow turbulence length scale becomes comparable to the airfoil thickness in the LE region, resulting in a higher concentration of vortices near the LE oriented in the transverse direction, creating high-velocity fluctuations in the spanwise direction. The near- and far-field pressure fluctuations are analyzed to understand the impact of the inflow turbulence distortion on these parameters and the limitations of analytical methods for real airfoils. Results show that the wall-pressure fluctuations are affected by the turbulence distortion in the LE region. Thick airfoils have noise directivity patterns significantly different compared to the Amiet predictions for higher frequencies, radiating higher noise levels upstream of the LE than the thin airfoil. This is likely associated with a drastic change in the pressure fluctuation distribution near the airfoil LE region, attributed to the change in the distortion of the vortical structures in the LE area.</p

Wheat Production Performance In Response To Nitrogen Sidedressing And Molybdenum Leaf Application

The application of nitrogen (N) at the appropriate time can be effective for crop productivity, changing the grain yield by increasing yield components. Thus, new alternatives that enable a better application of N fertilizer are sought. The aim of this study was to evaluate the components of yield and productivity of wheat cultivated with different doses of N sidedressing and molybdenum (Mo) via leaf application, using two cultivars, CD 150 and Quartzo. The experiment was conducted in the crop years of 2013 and 2014. The experiment used a randomized, factorial 4 x 4 block design, with four replicates. Four doses of N sidedressing in the form of urea were applied (0, 30, 60, and 90 kg ha-1) during tillering. In the same period, leaf molybdic fertilizer was applied, using four dosages of Mo in the form of potassium molybdate (0, 20, 40, and 60 g ha-1). Grain number per ear (GNPE), 1,000-grain mass (TGM), hectoliter weight (HW), and grain productivity (PROD) were evaluated. N fertilizer sidedressing did not promote the yield components of either of the wheat cultivars, although the GNPE of the Quartzo cultivar increased with increasing N doses in both crop years. The increase in N fertilizer increased the PROD of both wheat cultivars. The foliar application of Mo did not promote the yield components or wheat PROD of either cultivar. The HW was influenced by N and Mo rates, and was reduced in the absence of either of these fertilizer elements, indicating that the two nutrients were dependent on each other.3752963297

Cryptosporidium Spp. And Giardia Spp. In Feces And Water And The Associated Exposure Factors On Dairy Farms

The aims of this study were to verify the prevalence of Cryptosporidium spp. and Giardia spp. in animal feces and drinking water on dairy farms and to identify a possible relation between the exposure factors and the presence of these parasites. Fecal samples from cattle and humans and water samples were collected on dairy farms in Paraná, Brazil. Analysis of (oo)cysts in the feces was performed by the modified Ziehl-Neelsen staining and centrifugal flotation in zinc sulfate. Test-positive samples were subjected to nested PCR amplification of the 18SSU ribosomal RNA gene for identification of Cryptosporidium and Giardia and of the gp60 gene for subtyping of Cryptosporidium. Microbiological analysis of water was carried out by the multiple-tube method and by means of a chromogenic substrate, and parasitological analysis was performed on 31 samples by direct immunofluorescence and nested PCR of the genes mentioned above. Identification of the species of Cryptosporidium was performed by sequencing and PCR with analysis of restriction fragment length polymorphisms. The prevalence of Giardia and Cryptosporidium was higher in calves than in adults. Among the samples of cattle feces, Cryptosporidium parvum was identified in 41 (64%), C. ryanae in eight (12.5%), C. bovis in four (6.3%), C. andersoni in five (7.8%), and a mixed infection in 20 samples (31.3%). These parasites were not identified in the samples of human feces. Thermotolerant coliform bacteria were identified in 25 samples of water (45.5%). Giardia duodenalis and C. parvum were identified in three water samples. The gp60 gene analysis of C. parvum isolates revealed the presence of two strains (IIaA20G1R1 and IIaA17G2R2) in the fecal samples and one (IIaA17G2R1) in the water samples. The presence of coliforms was associated with the water source, structure and degradation of springs, rain, and turbidity. The prevalence of protozoa was higher in calves up to six months of age. C. parvum and G. duodenalis were identified in the water of dairy farms, as were thermotolerant coliforms; these findings point to the need for guidance on handling of animals, preservation of water sources, and water treatment. © 2017 Toledo et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.12

Anatomical study and phytochemical screening of leaves from Eucalyptus benthamii Maiden et Cambage

O óleo essencial das folhas de Eucalyptus benthamii Maiden et Cambage, espécie de elevada resistência ao frio, contém α-pineno como constituinte majoritário. Este trabalho avaliou a anatomia foliar de E. benthamii e realizou um screening fitoquímico para investigar a presença de outros metabólitos secundários nas folhas desse táxon. A partir do material botânico fixado, foram conduzidas as análises anatômicas, utilizando os métodos usuais de microscopia fotônica e eletrônica. O screening fitoquímico foi desenvolvido por meio de reações específicas para triterpenos/esteróides, alcalóides, antraquinonas, cumarinas, flavonóides, saponinas e taninos. A anatomia foliar evidenciou estômatos anomocíticos em ambas as faces do limbo foliar, mesofilo heterogêneo simétrico isobilateral, nervura mediana plano-convexa e sistema vascular do tipo bicolateral em arco aberto. Também foram visualizados idioblastos contendo cristais de oxalato de cálcio, cavidades secretoras com conteúdo lipofílico e súber cicatricial. O estudo fitoquímico revelou a presença de triterpenos e/ou esteróides, glicosídeos flavônicos, glicosídeos saponínicos e taninos.Eucalyptus benthamii Maiden et Cambage is a species with remarkable cold tolerance. Its essential oil showed α-pinene as the major constituent. The aim of this paper was to evaluate the anatomy of leaves from E. benthamii. Also a phytochemical screening of others secondary metabolites was investigated. The anatomical analyses of previously fixed leaves from E. benthamii were performed by the usual light and scanning microtechniques. Phytochemical study was carried out by qualitative reactions for triterpenes/steroids, alkaloids, anthraquinones, coumarins, flavonoids, saponins and tannins. Anomocytic stomata were observed on both surfaces of leaves from E. benthamii. Foliar blade showed a heterogeneous and symmetrical mesophyll as isobilateral arrange. The midrib showed plain-convex cross-section and was traversed by a bicollateral vascular bundle in open arc. Idioblasts with calcium oxalate prisms, secretory cavities with oil content and lenticel-like structures were also reported. The phytochemical screening revealed triterpenes/steroids, flavonoid glycosides, saponin glycosides and tannins.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Collapse dynamics of trapped Bose-Einstein condensates

We analyze the implosion and subsequent explosion of a trapped condensate after the scattering length is switched to a negative value. Our results compare very well qualitatively and fairly well quantitatively with the results of recent experiments at JILA.Comment: 4 pages, 3 figure

Metastable neon collisions: anisotropy and scattering length

In this paper we investigate the effective scattering length $a$ of spin-polarized Ne*. Due to its anisotropic electrostatic interaction, its scattering length is determined by five interaction potentials instead of one, even in the spin-polarized case, a unique property among the Bose condensed species and candidates. Because the interaction potentials of Ne* are not known accurately enough to predict the value of the scattering length, we investigate the behavior of $a$ as a function of the five phase integrals corresponding to the five interaction potentials. We find that the scattering length has five resonances instead of only one and cannot be described by a simple gas-kinetic approach or the DIS approximation. However, the probability for finding a positive or large value of the scattering length is not enhanced compared to the single potential case. The complex behavior of $a$ is studied by comparing a quantum mechanical five-channel numerical calculation to simpler two-channel models. We find that the induced dipole-dipole interaction is responsible for coupling between the different |\Omega> states, resulting in an inhomogeneous shift of the resonance positions and widths in the quantum mechanical calculation as compared to the DIS approach. The dependence of the resonance positions and widths on the input potentials turns out to be rather straightforward. The existence of two bosonic isotopes of Ne* enables us to choose the isotope with the most favorable scattering length for efficient evaporative cooling towards the Bose-Einstein Condensation transition, greatly enhancing the feasibility to reach this transition.Comment: 13pages, 8 eps figures, analytical model in section V has been remove

Sílice de las Algas Diatomeas (Clase Bacillariophyceae) como material complejo y su importancia nanotecnológica

The presence of mineral deposition is very common in microorganisms, plants, mushrooms and mammals. This organisms are an excellent natural model to study the relation between the principal parts involved in the process, the biopolymeric and mineral phases. The importance of this kind of studies is the relation with nanotechnology. Being a relatively new science, nanotechnology studies the chemical and physical phenomena is a scale under the 500 nanometers. When the system under study has a biological significance, with active biologic structures, the term bionanotechnology is used. This is the case of the study of the biomineralization in diatomeas seaweed. Due to the difficulty in the production of controlled micro and nanostructures containing silica (SiO2), this study is relevant. The possible technological applications of this kind of crystals are drug liberation structures, photovoltaic cells and high performance ceramic materials. Factors that affect the geometry, mechanical and physicochemical properties are poorly understood, whereby this kind of studies are important. Understanding the interactions and processes involved in the production of biological crystals could yield to a rational production of new and sophisticated nanostructured material with a broad application in nanotechnology (hybrid semiconductors), biology and biomedicime (biomaterials, drug liberation structures). In the work we establish a “bottom up” draft of the synthesis of “biosilica” by diatomeas emphasizing the impact in nanotechnology.La presencia de depósitos minerales es muy común en microorganismos, plantas, hongos y mamíferos. Estos organismos son, por lo tanto, un modelo natural excelente para estudiar la relación entre las principales partes que los componen, es decir la fase biopolímérica y la mineral. La importancia de este tipo de estudios se relaciona directamente con la nanotecnología, una rama científica relativamente reciente, encargada de estudiar los fenómenos químicos y físicos a escalas menores a los 500 nm. Cuando el sistema de estudio tiene importancia biológica, posee estructuras biológicamente activas o procede de un sistema biológico, se llama entonces bionanotecnología. Este es el caso del estudio de la biomineralización en las algas diatomeas. Esta línea de investigación tiene alta relevancia por la dificultad de producir micro y nanoestructuras altamente controladas de dióxido de silicio o sílice (SiO2), un tipo de vidrio que tiene potencialmente aplicaciones tecnológicas en liberación de drogas, celdas solares y materiales cerámicos de alto rendimiento. Los factores que afectan la geometría, las propiedades mecánicas y fisicoquímicas en estas estructuras son pobremente comprendidos, por lo que este tipo de estudios es de suma importancia. Si se logra entender las interacciones y los procesos de formación en estos sistemas que producen vidrio en entes biológicos, podremos acercarnos racionalmente a la síntesis de nuevos y sofisticados materiales nanoestructurados, con aplicaciones en una gran gama de áreas que van desde la nanotecnología (semiconductores híbridos) hasta la biología y biomedicina (biomateriales y estructuras liberadoras de drogas). En el presente trabajo se hace un esbozo “ascendente” (bottomup) de la síntesis de “biosilice” en diatomeas donde se enfatiza la importancia de este fenómeno en la nanotecnología

Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tetheredballoon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2-3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds