Granulometry is an initial factor to be considered in soil research as it plays a fundamental role in physical and chemical properties. The objective of this study was to characterize the granulometric fractions of soil, obtained using the screening and sedimentation method. The Dynamic Light Scattering (DLS), Mid-Infrared (MIR), and Scanning Electron Microscopy with Field Emission Gun (SEM-FEG) techniques were used for this purpose. The quantitative results showed that this soil presents high percentage of clay, followed by fine sand fraction, silt fraction and, finally, the coarse sand fraction. The results obtained by DLS qualify this technique as a procedure to evaluate the quality of the granulometric fractionation of the clay fraction. The MIR analyzes detected characteristic vibrational states of minerals such as kaolinite, halloysite, gibbsite, and quartz. Few works in the literature characterize the clay fraction of the soil without chemical treatment using the SEM-FEG technique. Thus, in this work, pseudo-hexagonal structures were identified, typical of the kaolinite mineral and, to a lesser extent, structures with a filamentous needle-like morphology, which can be ascribed to illite and/or halloysite, whose inorganic functional groups were identified by MIR in the clay fraction of the soil.

ABSTRACT Use of soil in forensic science is related to its several chemical, physical, and biological properties associated with its capacity to adhere to different materials and surfaces. Forensic soil experts and police investigators have been using soil samples as an aid in criminal investigations. Soils can act as fingerprints because they present contrasting physical, chemical, biological, and mineralogical properties. However, depending on the analytical tools utilized to characterize the soil, differentiating the samples when they have similar properties might be impossible. Thus, soil utilization as a fingerprint material requires increasing the number of variables measured as well as the accuracy and precision of the measurements. This study presents the feasibility of methods based on X-ray fluorescence (XRF) and radiation interaction parameters to discriminate soils for forensic investigations. Analyses of soil particle size, elemental composition (XRF), mass attenuation coefficient (μ), atomic (σa) and electronic (σe) cross-sections, effective atomic number (Zeff), and electron density (Nel) were carried out to evaluate the potential of nuclear parameters to differentiate soils. Ten different soil types collected at 0.00-0.05 m layer were studied. The radiation interaction parameters were obtained through the XCOM computer code, while the experimental measurements were carried out by the traditional gamma-ray attenuation method utilizing the radioactive sources of 241Am and 137Cs. The results showed that the soils presented broad differences in terms of clay, silt, and sand contents as well as in the major oxides. These differences influenced the radiation attenuation properties as verified through the multivariate analysis. For the lowest photon energy studied (10 and 30 keV), σe was the most interesting parameter to discriminate the soils. For energies above 59.5 keV, Zeff and Nel were the most important parameters. Good agreement was found between the calculated and measured parameters. The findings of this study indicate that radiation interaction parameters have great potential for crime scene investigation providing new parameters for better discrimination of soils. The main advantage of the method presented here is that it is fast, easy to implement, does not require powerful computers, and the XCOM code can be run online at the NIST (National Institute of Standards and Technology, USA) website.

Abstract The purpose of this research was to discriminate soil fractions using mineralogical and elemental analyses and to show those fractions that present greater contribution to the soil mass attenuation coefficient (μ) as well as their partial cross-sections for photoelectric absorption (PA), coherent scattering (CS) and incoherent scattering (IS). Soil samples from different places of Brazil classified as Yellow Argisol, Yellow Latosol and Gray Argisol were submitted to elemental and mineralogical analyses through energy dispersive X-ray fluorescence (EDXRF) and Rietveld Method with X-ray diffraction data (RM-XRD). The mixture rule was utilized to calculate μ of each soil. The EDXRF analysis showed as predominant elements Si, Al, Fe and Ti oxides. The highest contents were Si (914.3 to 981.3 g kg-1) in the sand fractions, Al (507.9 to 543.7 g kg-1) and Fe (32.5 to 76.7 g kg-1) in the clay fractions, and Ti (18.0 to 59.0 g kg-1) in the silt fractions. The RM-XRD allowed identifying that the sand fractions are predominantly made of quartz (913.3 to 995.0 g kg-1), while the clay greatest portion is made of kaolinite (465.0 to 660.6 g kg-1) and halloysite (169.0 to 385.0 g kg-1). The main effect responsible for μ was IS (50 to 61.4%) followed by PA (28 to 40.1%) and CS (9.9 to 10.6%). By using the principal component analysis (PC-1: 57.5% and PC-2: 20.9%), the samples were differentiated through the discrimination between physical, chemical and mineralogical properties. The results obtained suggest that general information about the radiation interaction in soils can be obtained through the elemental and mineralogical analyses of their fractions.

Este trabalho trata da análise dos centros de massa e do cálculo da estabilidade das quatro posturas básicas do Kung Fu Pak Hok. Embora a biomecânica tenha surgido em 1960, a sua aplicação em artes marciais, como no Kung Fu ainda é pouco frequente. Apesar de haver estudos de movimentos do Kung Fu, não há trabalhos sobre o centro de massa e a estabilidade para as posturas mais básicas. Este trabalho como objetivo descrever o centro de massa e a estabilidade das quatro posturas mais básicas do Kung-fu Pak Hok usando o método analítico por imagem de forma que seja possível sua utilização no ensino de física de forma contextualizada, e também em conjunto com a Educação Física. O cálculo da estabilidade foi realizado por meio do conceito de estabilidade entre os torques estabelecidos entre a força peso e uma força desestabilizadora. Os centros de massa em cada uma das quatro posturas se mantiveram muito próximos da região do umbigo. Foi verificado que as posturas mais estáveis corroboram com estâncias mais defensivas enquanto que posturas mais instáveis corroboram com estâncias mais ofensivas. Com isso, a análise quantitativa está de acordo com o conhecimento cultural e qualitativo associado ao Kung-fu.

In this paper we analyse the mass center and the postural stability of four basic Kung Fu Pak Hok postures. Although biomechanics arose in 60's, its application in martial arts such as Kung Fu, isn't often. There are few case studies which accounts the movements of Kung Fu, however there are none based on the study of its mass center and stability of its basic postures. This paper has as objective to describe the mass center and the stability of each of the four most basic postures of the Kung Fu Pak Hok using the image analytical method in a way that is possible to assemble Physics and Sports in an educational context. In order to calculate the mass center of each posture, it was carried out the image analytical method. The stability calculation was carried out by means of the equilibrium concept associated to the torques generated by the weight force and a destabilizing force. The mass center for each of the four postures was about the belly button. Also, it was noticed that the most stable postures were associated to defensive stances while unstable postures were associated to offensive stances. Nevertheless, the quantitative analysis stand on tune with the qualitative approach linked to the cultural background in the Kung Fu martial art.

RESUMO Atualmente há uma ampla investigação sobre ligas de alumínio, principalmente devido a sua larga aplicação na indústria automotiva e aeroespacial devida a características, como baixa densidade, alta condutividade térmica e elétrica, além de elevada resistência à corrosão a temperatura ambiente. Ligas de Al-Fe possuem um alto grau de modificação de sua microestrutura, no caso da utilização de um tratamento adequado, permitindo, assim, o aprimoramento de suas propriedades. Neste trabalho, a amostra estudada foi a liga Al-1,5%Fe tratada através da refusão superficial a laser (RSL) de modo a aprimorar suas características superficiais. A identificação dessa liga, com relação às fases presentes, foi realizada por meio dos difratogramas de raios X com ângulo de incidência rasante (DRXIR), em função da profundidade. Nesta técnica, o ângulo de incidência dos raios X é fixo e o detector move-se fazendo a varredura 2θ, a fim de obter difratogramas em diferentes profundidades variando-se apenas o ângulo de incidência. A análise foi realizada em escala micrométrica em duas condições de coleta de dados diferentes de DRXIR. A primeira variou-se o ângulo de incidência entre 0,5° a 6°, com intervalos de 0,5°, em modo de varredura contínua de 20º a 90°. A segunda, em ângulos de incidência 3° e 6°, em modo de varredura passo a passo de 20° a 120°, usada para melhorar a qualidade dos difratogramas e, em consequência, a melhoria da identificação de fases. Como resultado, foi realizado a caracterização microestrutural da superfície tradada pela técnica de RSL, bem como da parte transversal da camada tratada por meio de microscopia ótica (MO), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS) e por meio de DRXIR da camada tratada em função da profundidade, a identificação de fases simples, como o Al e o Fe, e metaestáveis, como o AlN, Al2,144O3,2 e o Al2O3, em uma camada entre 0,6 a 7,8 µm, como consequência da alta velocidade de resfriamento e do tratamento de RSL ter sido realizado em atmosfera não controlada e sem gás de proteção.

ABSTRACT There are currently an extensive research on aluminum alloys, mainly due to its wide application in the automo-tive and aerospace industry, due to its characteristics, such as, low density, high thermal and eletric conductivity and high corrosion resistance at room temperature. Fe-Al alloys have a high degree of modification of their mi-crostructure when used an appropriate treatment, consequently to improve their properties. In this work, the study sample was Al-1.5 wt.% Fe alloy treated through laser superficial remelting (LSR) in order to improve its surface characteristics. The identification of this alloy, with respect the present phases, was performed by means of grazing incidence X-ray diffraction (GIXRD) as a function of depth. In this technique, the angle incidence of X-rays is fixed, and the scanning 2θ detected by detector, in order to obtain diffraction patterns at different depths varying only the angle of incidence. The analysis was performed in micrometer scale in two different collections DRXIR data. First, the angle of incidence was varied from 0.5° to 6°, at intervals of 0.5° in continuous scan mode from 20° to 90°. The second, with incidence angles of 3° and 6°, for step scan mode at 20° to 120°, used to improve the quality of diffraction patterns, and hence improve the identification phase. As a result, characterization of the microstructure of the surface treated by the technique LSR, as well as the cross section of the treated layer by SEM and light microscopy and energy dispersive spectroscopy (EDS) was made, furthermore, to the application of the technique GIXRD, phase profile as a function of depth in a layer 0.6 to 7.8 µm were obtained, metastable phases, such as AlN, Al2O3 and Al2.144O3.2, and simple phase, as Al and Fe were identified in consequence of the high cooling speed and the treatment was conducted in the atmospheric environment.

RESUMO Densidade de partículas, umidades gravimétrica e volumétrica e porosidade são conceitos básicos importantes para caracterizar sistemas porosos, como é o caso do solo. Neste estudo, apresentou-se uma proposta de método experimental para a medida dessas grandezas físicas, em aulas de física experimental, em amostras de meios porosos compostos de esferas de diâmetros iguais (meio monodisperso) e diâmetros diferentes (meio polidisperso). A não utilização de amostras de solo é em razão da dificuldade de trabalhar com amostras desse meio poroso em laboratórios dedicados ao ensino de física experimental básica. O artigo apresenta o método a ser seguido e os resultados para dois estudos de caso, um meio monodisperso e outro polidisperso. Os resultados de densidade de partículas apresentados foram bastante próximos dos valores teóricos para as esferas de chumbo, cujo desvio relativo (DR) foi de -2,9 %, e para as esferas de ferro, de +0,1 %. A porosidade também evidenciou baixos DR, -3,6 %, para esferas de chumbo, e -1,2 %, para esferas de ferro, na comparação dos procedimentos, utilizando as densidades de partículas e do meio poroso e a umidade volumétrica de saturação, e dos meios monodisperso e polidisperso.

ABSTRACT Particle density, gravimetric and volumetric water contents and porosity are important basic concepts to characterize porous systems such as soils. This paper presents a proposal of an experimental method to measure these physical properties, applicable in experimental physics classes, in porous media samples consisting of spheres with the same diameter (monodisperse medium) and with different diameters (polydisperse medium). Soil samples are not used given the difficulty of working with this porous medium in laboratories dedicated to teaching basic experimental physics. The paper describes the method to be followed and results of two case studies, one in monodisperse medium and the other in polydisperse medium. The particle density results were very close to theoretical values for lead spheres, whose relative deviation (RD) was -2.9 % and +0.1 % RD for the iron spheres. The RD of porosity was also low: -3.6 % for lead spheres and -1.2 % for iron spheres, in the comparison of procedures – using particle and porous medium densities and saturated volumetric water content – and monodisperse and polydisperse media.

A caracterização mineralógica por meio da quantificação dos minerais presentes em solos brasileiros por difração de raios X usando o Método de Rietveld é, ainda, pouco comum. Neste trabalho foi realizada a quantificação mineralógica de um Latossolo Vermelho ácrico da região de Ponta Grossa, Paraná, Brasil, utilizando o Método de Rietveld com dados de Difração de Raios X e também verificado se o método foi adequado na quantificação mineral de um solo altamente intemperizado. Os horizontes A, AB e B3 foram separados fisicamente nas frações: argila, silte, areia fina (por meio da Lei de Stokes) e areia grossa (por peneiramento) sem qualquer tratamento químico. As técnicas de Fluorescência de raios X, Espectroscopia de Emissão Atômica com Fonte de Plasma Induzido, Espectroscopia de Infravermelho e Espectroscopia Mössbauer foram utilizadas para auxiliar na identificação e quantificação dos minerais. O Método de Rietveld possibilitou a quantificação dos minerais presentes nas frações argila e silte de todos os horizontes: quartzo, gibbsita, rutílio, hematita, goethita, caulinita e haloisita. Na fração silte os horizontes mais profundos são diferentes do mais superficial devido à presença de grandes quantidades de quartzo. As frações areia fina e grossa são constituídas principalmente de quartzo. Portanto, o Método de Rietveld foi adequado para quantificação dos minerais, principalmente, das frações mais finas (argila e silte).

The mineralogical characterization through mineral quantification of Brazilian soils by X-ray diffraction data using the Rietveld Method is not common. A mineralogical quantification of an Acric Ferralsol from the Ponta Grossa region, state of Paraná, Brazil, was carried out using this Method with X-Ray Diffraction data to verify if this method was suitable for mineral quantification of a highly-weathered soil. The A, AB and B3 horizons were fractioned to separate the different particle sizes: clay, silt, fine sand (by Stokes Law) and coarse sand fractions (by sieving), with the procedure free of chemical treatments. X-ray Fluorescence, Inductively Coupled Plasma Atomic Emission Spectrometry, Infrared Spectroscopy and Mössbauer Spectroscopy were used in order to assist the mineral identification and quantification. The Rietveld Method enabled the quantification of the present minerals. In a general way, the quantitative mineralogical characterization by the Rietveld Method revealed that quartz, gibbsite, rutile, hematite, goethite, kaolinite and halloysite were present in the clay and silt fractions of all horizons. The silt fractions of the deeper horizons were different from the more superficial ones due to the presence of large amounts of quartz. The fine and the coarse sand fractions are constituted mainly by quartz. Therefore, a mineralogical quantification of the finer fraction (clay and silt) by the Rietveld Method was successful.

A coesão de horizontes de solos do Brasil vem sendo associada, principalmente, a fatores físicos e químicos inter-relacionados, mas a influência das propriedades mineralógicas e cristalográficas dos minerais da fração argila também foi aventada por alguns pesquisadores. Neste trabalho, testou-se a hipótese de que a fração argila de horizontes coesos de solos do Sedimento Barreiras da faixa dos Tabuleiros Costeiros é dominantemente caulinítica e apresenta elevado grau de cristalinidade e ordenamento, o que pode favorecer o ajuste face a face dos cristais. O objetivo deste trabalho foi avaliar as características mineralógicas e cristalográficas dos minerais da fração argila de horizontes coesos provenientes de solos de sedimentos do Grupo Barreiras e uma possível contribuição para a ocorrência do caráter coeso. Para isso, foram analisados cinco horizontes coesos e um não-coeso de solos distribuídos ao longo da faixa dos Tabuleiros Costeiros. Também foi incluída, como referência, uma caulinita com elevado grau de cristalinidade. Todos os perfis foram analisados para classificação taxonômica e localização dos horizontes de interesse. Nas amostras dos horizontes selecionados, foram removidos a matéria orgânica e os óxidos. Após a dispersão de partículas, a fração argila foi individualizada, tratada e analisada por difração de raios X (DRX) para determinar os minerais e o grau de ordem/desordem estrutural, segundo o Método Especialista de Plançon & Zacharie (1990). Todos os horizontes coesos apresentaram caulinitas com grau de ordenamento estrutural similar ao do horizonte não-coeso e inferior à caulinita de referência, o que não permitiu associar o empacotamento da fração argila com a manifestação do caráter coeso nos horizontes estudados, a partir das avalioações obtidas pelo método utilizado.

The cohesion of hardsetting horizons of Brazilian soils has been mainly associated to inter-related physical and chemical factors, but an influence of mineralogical and crystallographic properties of clay minerals was also suggested by some researchers. In this study we tested the possibility that clay fraction of hardsetting horizons of soils from the Barreiras sediments of Coastal Tablelands are predominantly kaolinitic and highly crystalline and organized, which can favor a face-to-face arrangement of the crystals. The purpose of this study was to evaluate the crystallographic and mineralogical characteristics of clay minerals in hardsetting soil horizons from the sediment group Barreiras and their contribution to the hardsetting character. One non-hardsetting and five hardsetting horizons were studied along the coastal tableland. A kaolinite sample with high crystallinity degree was also included as reference. All profiles were analyzed for taxonomic classification and location of the horizons of interest. Organic matter and oxides were removed from the samples of the selected horizons. After soil dispersion, the clay fraction was individualized, treated and examined by X-ray diffraction (XRD) to determine the minerals and structure degree of order/disorder, according to the method described by Plançon & Zacarie (1990). The degree of structural organization of the kaolinites of the hardsetting and non-hardsetting horizons was similar to and lower than the kaolinite used as reference. Results indicated that the hardsetting behavior of the studied soils could not be explained by clay packaging.

Atualmente, procuram-se sistemas de manejo que preservem ou melhorem as qualidades do solo, tanto mineralógicas como orgânicas, priorizando maior produtividade. Este trabalho teve como objetivo verificar qualitativamente, por meio das técnicas de fluorescência de raios X, difração de raios X e infravermelho com transformada de Fourier, os efeitos provocados pela utilização dos manejos: plantio convencional, preparo mínimo e plantio direto, por 24 anos, na mineralogia de um Latossolo Vermelho distrófico de Ponta Grossa, PR. Não foram observadas mudanças significativas na mineralogia do Latossolo estudado, por meio das técnicas utilizadas, quanto aos diferentes manejos durante os anos de sua aplicação. Pôde-se verificar, qualitativamente, a presença dos minerais gibbsita, caulinita, haloisita, montmorilonita, hematita, rutilo, anatásio, goethita e quartzo.

The search for management systems that preserve or improve soil qualities, the mineralogical as well as the organic composition, with a view to higher yields, is becoming more and more intense. The objective this study was to qualitatively verify the mineralogical effects of different management types: conventional , minimum and no-tillage for 24 years on a Red Latosol in Ponta Grossa, PR, Brazil, by the following techniques: X-ray diffraction, X-ray fluorescence and Fourier transform infrared. No significant changes in the mineralogy of the Red Latosol were observed by the techniques applied, as a result of the different management types. It was however possible to qualitatively verify the presence of the following minerals: gibbsite, kaolinite, halloysite, montmorillonite, hematite, rutile, anatase, goethite and quartz.

Laser-induced fluorescence spectroscopy was used to determine the humification degree of the organic matter of a whole soil, that is, soil without any physical or chemical treatment. Particle size was determined in physically separated fractions. The humification of organic matter, the depth of the soil and the planting system can be correlated. On the surface of the soil, no tillage provided the smallest humification in comparison with the conventional tillage and reduced tillage. The fractions of the superficial layer of the soil (0-20 cm) indicated larger humification in the fraction from 20 to 53 µm and the smallest in the fraction of <2 µm.