Dynamical scaling properties of nanoporous undoped and Sb-doped SnO2 supported thin films during tri- and bidimensional structure coarsening

The coarsening of the nanoporous structure developed in undoped and 3% Sb-doped SnO2 sol-gel dip-coated films deposited on a mica substrate was studied by time-resolved small-angle x-ray scattering (SAXS) during in situ isothermal treatments at 450 and 650 degrees C. The time dependence of the structure function derived from the experimental SAXS data is in reasonable agreement with the predictions of the statistical theory of dynamical scaling, thus suggesting that the coarsening process in the studied nanoporous structures exhibits dynamical self-similar properties. The kinetic exponents of the power time dependence of the characteristic scaling length of undoped SnO2 and 3% Sb-doped SnO2 films are similar (alpha approximate to 0.09), this value being invariant with respect to the firing temperature. In the case of undoped SnO2 films, another kinetic exponent, alpha('), corresponding to the maximum of the structure function was determined to be approximately equal to three times the value of the exponent alpha, as expected for the random tridimensional coarsening process in the dynamical scaling regime. Instead, for 3% Sb-doped SnO2 films fired at 650 degrees C, we have determined that alpha(')approximate to 2 alpha, thus suggesting a bidimensional coarsening of the porous structure. The analyses of the dynamical scaling functions and their asymptotic behavior at high q (q being the modulus of the scattering vector) provided additional evidence for the two-dimensional features of the pore structure of 3% Sb-doped SnO2 films. The presented experimental results support the hypotheses of the validity of the dynamic scaling concept to describe the coarsening process in anisotropic nanoporous systems.

A new bidimensional compound containing (μ-thiocyanate)(bpy)copper(II) molecules: synthesis, crystal structure and magnetic properties of [Cu(bpy)(NCS)2]n (bpy = 2,2'-bipyridyl)

The crystal structure of the first bidimensional copper(II) compound containing only thiocyanate as bridging ligands [Cu(bpy)(NCS) 2 ] n , where bpy=2,2'-bipyridyl, has been determined by X-ray diffraction on single-crystals. Two different environments for both types of copper(II) ions in the unit cell are apparent: a distorted octahedron and a square pyramid. A bidimensional structure with a deformed honeycomb-layer motif is formed, the bipyridyl ligands filling the interlayer space. The magnetic susceptibility data of the compound have been investigated between 280 and 1.8 K. The compound presents a very weak antiferromagnetic interaction that has been fitted by using the Bleaney-Bowers expression for a dimeric unit, whereby a J value of -1.01(1) cm - 1 (H=-JS 1 .S 2 ) and a g value of 2.08(1) have been obtained.

Efeito da variação de parâmetros reacionais na preparação de grafeno via oxidação e redução do grafite

This work shows the influence of several reactional parameters for obtaining graphene through successive steps of oxidation and exfoliation of bulk graphite (resulting in graphene oxide), followed by chemical reduction. The results showed that changes in temperature, reaction time, reducing agent and source of primary graphite lead to different surface compositions and stability in dispersion of graphene oxide. Also, the use of different reducing agents promoted different degrees of restoration of C=C bonds in the bidimensional structure of graphene.

Algorithm BIDIMS for Automated Systematization of Data Array. Case Study: Rediscovering Mendeleev’s Periodic Table of Chemical Elements

The method (algorithm BIDIMS) of multivariate objects display to bidimensional structure in which the sum of differences of objects properties and their nearest neighbors is minimal is being described. The basic regularities on the set of objects at this ordering become evident. Besides, such structures (tables) have high inductive opportunities: many latent properties of objects may be predicted on their coordinates in this table. Opportunities of a method are illustrated on an example of bidimentional ordering of chemical elements. The table received in result practically coincides with the periodic Mendeleev table.

Influence of stiffness in bolted connections in wooden plane structure of truss type

Trusses are structural systems commonly used in projects, being employed mainly in roof structures, present in most rural buildings. The design of trusses, as well as other structural systems, requires the determination of displacements, strains and stresses. However, the project is developed from an ideal model of calculation, considering free rotation between the elements of a connection. This paper presents a computer program for the analysis of bidimensional wooden trusses with connections formed with two screws per node. The formulation is based on the flexibility method, taking into account the influence of the effect of semi-rigid connections formed by two screws. An example of a structure is presented and analyzed by the program developed here, highlighting the importance of behavior analysis on semi-rigid connections.

Anatomia de la auriculilla izquierda: análisis comparativo por ecocardiografia transesofagica bidimensional y tridimensional

Introducción. La auriculilla izquierda es una estructura cardiaca que facilita la generación de trombos en su interior, favoreciendo la aparición de evento embolicos, por lo que su análisis a partir de imágenes bidimensionales y mas recientemente tridimensionales, adquieren cada vez mayor importancia Objetivo. Comparar los hallazgos anatómicos de la auriculilla izquierda obtenidos a través de la ecocardiografía tridimensional con respecto a los obtenidos por ecocardiografía bidimensional en un grupo de pacientes con ritmo sinusal y con fibrilación auricular. Métodos. Se trata de un estudio observacional analítico, transversal, en el que se compararan los resultados en las mediciones anatómicas obtenidas por ecocardiograma bidimensional en pacientes con rimo sinusal y fibrilación auricular, con los resultados de dichas mediciones obtenidas a través del ecocardiograma tridimensional en el mismo grupo de pacientes. Resultados. Se evaluaron 48 pacientes, 32 pacientes (66%) se encontraron en ritmo sinusal, la edad promedio fue de 58,2 años; 41,7% fueron mujeres y la mayoría, 32 pacientes (66,7%), tenían una o varias comorbilidades de importancia de riesgo cardiovascular, con evidencia de compromiso de la función sistólica en 20 paciente, encontrando una mayor homogeneidad en las variables área y profundidad de la auriculilla izquierda. Discusión. Los resultados nos permiten apoyar el concepto que las imágenes obtenidas por ecocardiografía tridimensional nos ofrecen una mejor evaluación de la auriculilla izquierda, observando una mayor homogeneidad con la ecocardiografía bidimensional en las variables área y profundidad, existiendo a su vez heterogeneidad en la variable longitud. Conclusión. El presente estudio demostró que la ecocardiografía tridimensional, es un aporte importante desde el punto de vista diagnostico tanto cualitativo como cuantitativo en el análisis de la auriculilla izquierda, permitiendo una fácil adquisición de imágenes en tiempo real y comparativas con las imágenes bidimensionales.

Analysis of the problems associated with dynamic interaction between train, track and structure at transition zones

El gran desarrollo experimentado por la alta velocidad en los principales países de la Unión Europea, en los últimos 30 años, hace que este campo haya sido y aún sea uno de los principales referentes en lo que a investigación se refiere. Por otra parte, la aparición del concepto super − alta velocidad hace que la investigación en el campo de la ingeniería ferroviaria siga adquiriendo importancia en los principales centros de investigación de los países en los que se desea implantar este modo de transporte, o en los que habiendo sido ya implantado, se pretenda mejorar. Las premisas de eficacia, eficiencia, seguridad y confort, que este medio de transporte tiene como razón de ser pueden verse comprometidas por diversos factores. Las zonas de transición, definidas en la ingeniería ferroviaria como aquellas secciones en las que se produce un cambio en las condiciones de soporte de la vía, pueden afectar al normal comportamiento para el que fue diseñada la infraestructura, comprometiendo seriamente los estándares de eficiencia en el tiempo de viaje, confort de los pasajeros y aumentando considerablemente los costes de mantenimiento de la vía, si no se toman las medidas oportunas. En esta tesis se realiza un estudio detallado de la zonas de transición, concretamente de aquellas en las que existe una cambio en la rigidez vertical de la vía debido a la presencia de un marco hidráulico. Para realizar dicho estudio se lleva a cabo un análisis numérico de interacción entre el vehículo y la estructura, con un modelo bidimensional de elemento finitos, calibrado experimentalmente, en estado de tensión plana. En este análisis se tiene en cuenta el efecto de las irregularidades de la vía y el comportamiento mecánico de la interfaz suelo-estructura, con el objetivo de reproducir de la forma más real posible el efecto de interacción entre el vehículo, la vía y la estructura. Otros efectos como la influencia de la velocidad del tren y los asientos diferenciales, debidos a deformaciones por consolidación de los terraplenes a ambos lados el marco hidráulico, son también analizados en este trabajo. En esta tesis, los cálculos de interacción se han llevado a cabo en dos fases diferentes. En la primera, se ha considerado una interacción sencilla debida al paso de un bogie de un tren Eurostar. Los cálculos derivados de esta fase se han denominado cálculos a corto plazo. En la segunda, se ha realizado un análisis considerando múltiples pasos de bogie del tren Eurostar, conformando un análisis de degradación en el que se tiene en cuenta, en cada ciclo, la deformación de la capa de balasto. Los cálculos derivados de esta fase, son denominados en el texto como cálculos a largo plazo. Los resultados analizados muestran que la utilización de los denominados elementos de contacto es fundamental cuando se desea estudiar la influencia de asientos diferenciales, especialmente en transiciones terraplén-estructura en las que la cuña de cimentación no llega hasta la base de cimentación de la estructura. Por otra parte, tener en cuenta los asientos del terraplén, es sumamente importante, cuando se desea realizar un análisis de degradación de la vía ya que su influencia en la interacción entre el vehículo y la vía es muy elevada, especialmente para valores altos de velocidad del tren. En cuanto a la influencia de las irregularidades de la vía, en los cálculos efectuados, se revela que su importancia es muy notable, siendo su influencia muy destacada cuanto mayor sea la velocidad del tren. En este punto cabe destacar la diferencia de resultados derivada de la consideración de perfiles de irregularidades de distinta naturaleza. Los resultados provenientes de considerar perfiles artificiales son en general muy elevados, siendo estos más apropiados para realizar estudios de otra índole, como por ejemplo de seguridad al descarrilamiento. Los resultados provenientes de perfiles reales, dados por diferentes Administradores ferroviarios, presentan resultados menos elevados y más propios del problema analizar. Su influencia en la interacción dinámica entre el vehículo y la vía es muy importante, especialmente para velocidades elevadas del tren. Además el fenómeno de degradación conocido como danza de traviesas, asociado a zonas de transición, es muy susceptible a la consideración de irregularidades de la vía, tal y como se desprende de los cálculos efectuados a largo plazo. The major development experienced by high speed in the main countries of the European Union, in the last 30 years, makes railway research one of the main references in the research field. It should also be mentioned that the emergence of the concept superhigh − speed makes research in the field of Railway Engineering continues to gain importance in major research centers in the countries in which this mode of transportation is already implemented or planned to be implemented. The characteristics that this transport has as rationale such as: effectiveness, efficiency, safety and comfort, may be compromised by several factors. The transition zones are defined in railway engineering as a region in which there is an abrupt change of track stiffness. This stiffness variation can affect the normal behavior for which the infrastructure has been designed, seriously compromising efficiency standards in the travel time, passenger comfort and significantly increasing the costs of track maintenance, if appropriate measures are not taken. In this thesis a detailed study of the transition zones has been performed, particularly of those in which there is a change in vertical stiffness of the track due to the presence of a reinforced concrete culvert. To perform such a study a numerical interaction analysis between the vehicle, the track and the structure has been developed. With this purpose a two-dimensional finite element model, experimentally calibrated, in a state of plane stress, has been used. The implemented numerical models have considered the effects of track irregularities and mechanical behavior of soil-structure interface, with the objective of reproducing as accurately as possible the dynamic interaction between the vehicle the track and the structure. Other effects such as the influence of train speed and differential settlement, due to secondary consolidation of the embankments on both sides of culvert, have also been analyzed. In this work, the interaction analysis has been carried out in two different phases. In the first part a simple interaction due to the passage of a bogie of a Eurostar train has been considered. Calculations derived from this phase have been named short-term analysis. In the second part, a multi-load assessment considering an Eurostar train bogie moving along the transition zone, has been performed. The objective here is to simulate a degradation process in which vertical deformation of the ballast layer was considered. Calculations derived from this phase have been named long-term analysis. The analyzed results show that the use of so-called contact elements is essential when one wants to analyze the influence of differential settlements, especially in embankment-structure transitions in which the wedge-shaped backfill does not reach the foundation base of the structure. Moreover, considering embankment settlement is extremely important when it is desired to perform an analysis of track degradation. In these cases the influence on the interaction behaviour between the vehicle and the track is very high, especially for higher values of speed train. Regarding the influence of the track irregularities, this study has proven that the track’s dynamic response is heavily influenced by the irregularity profile and that this influence is more important for higher train velocities. It should also be noted that the difference in results derived from consideration of irregularities profiles of different nature. The results coming from artificial profiles are generally very high, these might be more appropriate in order to study other effects, such as derailment safety. Results from real profiles, given by the monitoring works of different rail Managers, are softer and they fit better to the context of this thesis. The influence of irregularity profiles on the dynamic interaction between the train and the track is very important, especially for high-speeds of the train. Furthermore, the degradation phenomenon known as hanging sleepers, associated with transition zones, is very susceptible to the consideration of track irregularities, as it can be concluded from the long-term analysis.

Changes In Chromatin Structure In Nih 3t3 Cells Induced By Valproic Acid And Trichostatin A.

Valproic acid (VPA) and trichostatin A (TSA) are known histone deacetylase inhibitors (HDACIs) with epigenetic activity that affect chromatin supra-organization, nuclear architecture, and cellular proliferation, particularly in tumor cells. In this study, chromatin remodeling with effects extending to heterochromatic areas was investigated by image analysis in non-transformed NIH 3T3 cells treated for different periods with different doses of VPA and TSA under conditions that indicated no loss of cell viability. Image analysis revealed chromatin decondensation that affected not only euchromatin but also heterochromatin, concomitant with a decreased activity of histone deacetylases and a general increase in histone H3 acetylation. Heterochromatin protein 1-α (HP1-α), identified immunocytochemically, was depleted from the pericentromeric heterochromatin following exposure to both HDACIs. Drastic changes affecting cell proliferation and micronucleation but not alteration in CCND2 expression and in ratios of Bcl-2/Bax expression and cell death occurred following a 48-h exposure of the NIH 3T3 cells particularly in response to higher doses of VPA. Our results demonstrated that even low doses of VPA (0.05 mM) and TSA (10 ng/ml) treatments for 1 h can affect chromatin structure, including that of the heterochromatin areas, in non-transformed cells. HP1-α depletion, probably related to histone demethylation at H3K9me3, in addition to the effect of VPA and TSA on histone H3 acetylation, is induced on NIH 3T3 cells. Despite these facts, alterations in cell proliferation and micronucleation, possibly depending on mitotic spindle defects, require a longer exposure to higher doses of VPA and TSA.

Matrix Metalloproteinases And Left Ventricular Function And Structure In Spinal Cord Injured Subjects.

Subjects with spinal cord injury (SCI) exhibit impaired left ventricular (LV) diastolic function, which has been reported to be attenuated by regular physical activity. This study investigated the relationship between circulating matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) and echocardiographic parameters in SCI subjects and the role of physical activity in this regard. Forty-two men with SCI [19 sedentary (S-SCI) and 23 physically-active (PA-SCI)] were evaluated by clinical, anthropometric, laboratory, and echocardiographic analysis. Plasmatic pro-MMP-2, MMP-2, MMP-8, pro-MMP-9, MMP-9, TIMP-1 and TIMP-2 levels were determined by enzyme-linked immunosorbent assay and zymography. PA-SCI subjects presented lower pro-MMP-2 and pro-MMP-2/TIMP-2 levels and improved markers of LV diastolic function (lower E/Em and higher Em and E/A values) than S-SCI ones. Bivariate analysis showed that pro-MMP-2 correlated inversely with Em and directly with E/Em, while MMP-9 correlated directly with LV mass index and LV end-diastolic diameter in the whole sample. Following multiple regression analysis, pro-MMP-2, but not physical activity, remained associated with Em, while MMP-9 was associated with LV mass index in the whole sample. These findings suggest differing roles for MMPs in LV structure and function regulation and an interaction among pro-MMP-2, diastolic function and physical activity in SCI subjects.

Growth Factor Stimulation Improves The Structure And Properties Of Scaffold-free Engineered Auricular Cartilage Constructs.

The reconstruction of the external ear to correct congenital deformities or repair following trauma remains a significant challenge in reconstructive surgery. Previously, we have developed a novel approach to create scaffold-free, tissue engineering elastic cartilage constructs directly from a small population of donor cells. Although the developed constructs appeared to adopt the structural appearance of native auricular cartilage, the constructs displayed limited expression and poor localization of elastin. In the present study, the effect of growth factor supplementation (insulin, IGF-1, or TGF-β1) was investigated to stimulate elastogenesis as well as to improve overall tissue formation. Using rabbit auricular chondrocytes, bioreactor-cultivated constructs supplemented with either insulin or IGF-1 displayed increased deposition of cartilaginous ECM, improved mechanical properties, and thicknesses comparable to native auricular cartilage after 4 weeks of growth. Similarly, growth factor supplementation resulted in increased expression and improved localization of elastin, primarily restricted within the cartilaginous region of the tissue construct. Additional studies were conducted to determine whether scaffold-free engineered auricular cartilage constructs could be developed in the 3D shape of the external ear. Isolated auricular chondrocytes were grown in rapid-prototyped tissue culture molds with additional insulin or IGF-1 supplementation during bioreactor cultivation. Using this approach, the developed tissue constructs were flexible and had a 3D shape in very good agreement to the culture mold (average error <400 µm). While scaffold-free, engineered auricular cartilage constructs can be created with both the appropriate tissue structure and 3D shape of the external ear, future studies will be aimed assessing potential changes in construct shape and properties after subcutaneous implantation.

Ssr-based Genetic Diversity And Structure Of Garlic Accessions From Brazil.

Garlic is a spice and a medicinal plant; hence, there is an increasing interest in 'developing' new varieties with different culinary properties or with high content of nutraceutical compounds. Phenotypic traits and dominant molecular markers are predominantly used to evaluate the genetic diversity of garlic clones. However, 24 SSR markers (codominant) specific for garlic are available in the literature, fostering germplasm researches. In this study, we genotyped 130 garlic accessions from Brazil and abroad using 17 polymorphic SSR markers to assess the genetic diversity and structure. This is the first attempt to evaluate a large set of accessions maintained by Brazilian institutions. A high level of redundancy was detected in the collection (50 % of the accessions represented eight haplotypes). However, non-redundant accessions presented high genetic diversity. We detected on average five alleles per locus, Shannon index of 1.2, HO of 0.5, and HE of 0.6. A core collection was set with 17 accessions, covering 100 % of the alleles with minimum redundancy. Overall FST and D values indicate a strong genetic structure within accessions. Two major groups identified by both model-based (Bayesian approach) and hierarchical clustering (UPGMA dendrogram) techniques were coherent with the classification of accessions according to maturity time (growth cycle): early-late and midseason accessions. Assessing genetic diversity and structure of garlic collections is the first step towards an efficient management and conservation of accessions in genebanks, as well as to advance future genetic studies and improvement of garlic worldwide.

The Atomic Structure Of A Bare Buffer Layer On Sic(0001) Chemically Resolved.

A chemical-specific photoelectron diffraction structure determination of a carbon rich buffer layer on SiC is reported. In addition to the long-range ripple of this surface, a local buckling in the hexagonal sublattice, which breaks the local range order symmetry, was unraveled.

Crystal Structure Of (3e)-3-[(4-nitro-phen-oxy)-meth-yl]-4-phenyl-but-3-en-2-one.

In the title compound, C17H15NO4, the conformation about the C=C double bond [1.348 (2) Å] is E with the ketone group almost co-planar [C-C-C-C torsion angle = 7.2 (2)°] but the phenyl group twisted away [C-C-C-C = 160.93 (17)°]. The terminal aromatic rings are almost perpendicular to each other [dihedral angle = 81.61 (9)°] giving the mol-ecule an overall U-shape. The crystal packing feature benzene-C-H⋯O(ketone) contacts that lead to supra-molecular helical chains along the b axis. These are connected by π-π inter-actions between benzene and phenyl rings [inter-centroid distance = 3.6648 (14) Å], resulting in the formation of a supra-molecular layer in the bc plane.

Crystal Structure Of (3e)-3-(2,4-di-nitro-phen-oxy-meth-yl)-4-phenyl-but-3-en-2-one.

In the title compound, C17H14N2O6, the conformation about the C=C double bond [1.345 (2) Å] is E, with the ketone moiety almost coplanar [C-C-C-C torsion angle = 9.5 (2)°] along with the phenyl ring [C-C-C-C = 5.9 (2)°]. The aromatic rings are almost perpendicular to each other [dihedral angle = 86.66 (7)°]. The 4-nitro moiety is approximately coplanar with the benzene ring to which it is attached [O-N-C-C = 4.2 (2)°], whereas the one in the ortho position is twisted [O-N-C-C = 138.28 (13)°]. The mol-ecules associate via C-H⋯O inter-actions, involving both O atoms from the 2-nitro group, to form a helical supra-molecular chain along [010]. Nitro-nitro N⋯O inter-actions [2.8461 (19) Å] connect the chains into layers that stack along [001].

On The Consistency Of Monte Carlo Track Structure Dna Damage Simulations.

Monte Carlo track structures (MCTS) simulations have been recognized as useful tools for radiobiological modeling. However, the authors noticed several issues regarding the consistency of reported data. Therefore, in this work, they analyze the impact of various user defined parameters on simulated direct DNA damage yields. In addition, they draw attention to discrepancies in published literature in DNA strand break (SB) yields and selected methodologies. The MCTS code Geant4-DNA was used to compare radial dose profiles in a nanometer-scale region of interest (ROI) for photon sources of varying sizes and energies. Then, electron tracks of 0.28 keV-220 keV were superimposed on a geometric DNA model composed of 2.7 × 10(6) nucleosomes, and SBs were simulated according to four definitions based on energy deposits or energy transfers in DNA strand targets compared to a threshold energy ETH. The SB frequencies and complexities in nucleosomes as a function of incident electron energies were obtained. SBs were classified into higher order clusters such as single and double strand breaks (SSBs and DSBs) based on inter-SB distances and on the number of affected strands. Comparisons of different nonuniform dose distributions lacking charged particle equilibrium may lead to erroneous conclusions regarding the effect of energy on relative biological effectiveness. The energy transfer-based SB definitions give similar SB yields as the one based on energy deposit when ETH ≈ 10.79 eV, but deviate significantly for higher ETH values. Between 30 and 40 nucleosomes/Gy show at least one SB in the ROI. The number of nucleosomes that present a complex damage pattern of more than 2 SBs and the degree of complexity of the damage in these nucleosomes diminish as the incident electron energy increases. DNA damage classification into SSB and DSB is highly dependent on the definitions of these higher order structures and their implementations. The authors' show that, for the four studied models, different yields are expected by up to 54% for SSBs and by up to 32% for DSBs, as a function of the incident electrons energy and of the models being compared. MCTS simulations allow to compare direct DNA damage types and complexities induced by ionizing radiation. However, simulation results depend to a large degree on user-defined parameters, definitions, and algorithms such as: DNA model, dose distribution, SB definition, and the DNA damage clustering algorithm. These interdependencies should be well controlled during the simulations and explicitly reported when comparing results to experiments or calculations.