1,636 research outputs found
Treatability and CCA Preservative Distribution Within Ten Indonesian Hardwoods
Samples were cut from stems of 10 Indonesian hardwoods. They were conditioned to 12% moisture content and then pressure-treated in a commercial plant using CCA type C. Liquid preservative uptake, penetration depth, fraction of voids filled, and distribution (percent of each cell type penetrated) were measured. Heartwood and sapwood of many of the species had high uptakes and good penetration, making them promising candidates for further work. Some of the species that showed good uptake exhibited poorly treated fibers, ray cells, or axial parenchyma. Tyloses, gummy materials, axial parenchyma presence and location, and ray canals affected preservative liquid uptake and distribution
Modelling Direct Current Resistivity Of Wood Polymer Composites
Resistivity of wood and treated wood decreased with increasing MC and increasing polymer loading. A rule of mixtures model using decreasing resistivities of polymer and wood with increase in MC agreed reasonably with experimental results
Bending Strength and Stiffness of Caribbean Pine from Trinidad and Tobago
Small samples of Caribbean pine wood grown in Trinidad were measured for specific gravity, modulus of elasticity, and modulus of rupture in bending. Core and outer wood and samples from along the length of the tree were studied. Mechanical properties and specific gravity varied along and across the trees. Linear relationships between specific gravity and mechanical properties were better for the outer wood than for the core wood. Core wood was weaker than outer wood. The bolts varied in properties along the tree, with a maximum in the second 2-m bolt
Swelling of a Cell Lumen Filled and A Cell-Wall Bulked Wood Polymer Composite in Water
Liquid water swelling of lumen-filled and cell-wall bulked wood polymer composite (WPC) samples was measured at room temperature and 80 C. Ultimate swelling was greater (approximately that of untreated wood) and moisture diffusion coefficient lower for the lumen filled wood. The higher density, lumen filled sample had lower swelling than the lower density one. At 80 C, fiber saturation points (FSP) were 8% for the cell-wall samples and above 20% for the cell lumen samples. The FSP for more highly loaded cell lumen samples was lower than that for lower loading
The HR 4796A Debris System: Discovery of Extensive Exo-Ring Dust Material
The optically and IR bright, and starlight-scattering, HR 4796A ring-like
debris disk is one of the most (and best) studied exoplanetary debris systems.
The presence of a yet-undetected planet has been inferred (or suggested) from
the narrow width and inner/outer truncation radii of its r = 1.05" (77 au)
debris ring. We present new, highly sensitive, Hubble Space Telescope (HST)
visible-light images of the HR 4796A circumstellar debris system and its
environment over a very wide range of stellocentric angles from 0.32" (23 au)
to ~ 15" (1100 au). These very high contrast images were obtained with the
Space Telescope Imaging Spectrograph (STIS) using 6-roll PSF-template
subtracted coronagraphy suppressing the primary light of HR 4796A and using
three image plane occulters and simultaneously subtracting the background light
from its close angular proximity M2.5V companion. The resulting images
unambiguously reveal the debris ring embedded within a much larger,
morphologically complex, and bi-axially asymmetric exoring scattering
structure. These images at visible wavelengths are sensitive to, and map, the
spatial distribution, brightness, and radial surface density of micron size
particles over 5 dex in surface brightness. These particles in the exo-ring
environment may be unbound from the system and interacting with the local ISM.
Herein we present a new morphological and photometric view of the larger than
prior seen HR 4796A exoplanetary debris system with sensitivity to small
particles at stellocentric distances an order of magnitude greater than has
previously been observed.Comment: 28 pages, 17 figures, accepted for publication in the Astronomical
Journal 21 December 201
Magnetic Resonance Imaging of Water Concentration in Low Moisture Content Wood
A new magnetic resonance imaging (MRI) technique, termed SPRITE (Single Point Ramped Imaging with T1 Enhancement) permits visualization of water content in previously inaccessible wood fiber systems. We demonstrate the superiority of SPRITE methods, in comparison to conventional MRI methods, for studying fluid content in low water content wood materials. SPRITE and conventional MRI images were acquired from four species of wood, equilibrated at multiple moisture content levels. Both methods were also used to examine relative moisture content during forced drying of a white ash wood sample
Actitudes de emprendimiento y los "Cinco Grandes": una comparación intercultural entre España y Estados Unidos
Culture may interact with personality to facilitate or inhibit entrepreneurial behaviors. 296 undergraduates in the United States and 257 in Spain completed the Big Five Personality Inventory and the Entrepreneurial Attitudes Scale for Students (Mean age = 20.16 years; SD = 3.39). We hypothesized that across cultures, conscientiousness and openness would predict greater risk taking whereas neuroticism and agreeableness would be a negative correlate. Personality variables explained a larger proportion of the variance in entrepreneurial attitudes in the U.S. data. The associations between the personality dimensions and entrepreneurship varied considerably by country and gender. Significant positive correlations were found between conscientiousness and risk taking only for Spanish men. Neuroticism was significantly and negatively correlated with risk taking only for American participants.La cultura puede interactuar con la personalidad para facilitar o inhibir las conductas emprendedoras. 296 estudiantes universitarios en Estados Unidos y 257 en España completaron el inventario de los Cinco Grandes de Personalidad y la escala de Actitudes Emprendedoras para Estudiantes (Media de edad = 20.16 años; DT = 3.39). Se hipotetiza que, a través de culturas, conciencia y apertura serán predictores de mayor toma de riesgos, mientras neuroticismo y amigabilidad lo harán en negativo. Las variables de personalidad explican una mayor proporción de varianza en actitudes emprendedoras en los datos estadounidenses. Las asociaciones entre las dimensiones de personalidad y emprendimiento varían considerablemente por país y género. Se encontraron correlaciones positivas significativas entre conciencia y toma de riesgos solo en hombres españoles. El neuroticismo correlaciona negativa y significativamente con la toma de riesgos, solo en el caso de los participantes americanos
Revealing Asymmetries in the HD181327 Debris Disk: A Recent Massive Collision or Interstellar Medium Warping
New multi-roll coronagraphic images of the HD181327 debris disk obtained using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope reveal the debris ring in its entirety at high signal-to-noise ratio and unprecedented spatial resolution. We present and apply a new multi-roll image processing routine to identify and further remove quasi-static point-spread function-subtraction residuals and quantify systematic uncertainties. We also use a new iterative image deprojection technique to constrain the true disk geometry and aggressively remove any surface brightness asymmetries that can be explained without invoking dust density enhancements/ deficits. The measured empirical scattering phase function for the disk is more forward scattering than previously thought and is not well-fit by a Henyey-Greenstein function. The empirical scattering phase function varies with stellocentric distance, consistent with the expected radiation pressured-induced size segregation exterior to the belt. Within the belt, the empirical scattering phase function contradicts unperturbed debris ring models, suggesting the presence of an unseen planet. The radial profile of the flux density is degenerate with a radially varying scattering phase function; therefore estimates of the ring's true width and edge slope may be highly uncertain.We detect large scale asymmetries in the disk, consistent with either the recent catastrophic disruption of a body with mass greater than 1% the mass of Pluto, or disk warping due to strong interactions with the interstellar medium
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