Evaluating the impact of stand composition and competition on white spruce and aspen wood attributes in the boreal mixedwood

I evaluated how intra- and inter-specific competition affects the development of eleven wood attributes of trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench) Voss) over 34 years. My analysis was conducted in a mixedwood trial site in Northern British Columbia, Canada, that included treatments consisting of 0, 1000, 2000, 5000, and 10000 stems per hectare of aspen. Competition was found to negatively influence wood attribute development in aspen and positively impact spruce (at low levels of competition). Plot level competition indices were the best predictor of variation in aspen wood attributes, while stand level competition (population density) best explained the majority of spruce wood attributes. Maintaining aspen at lower densities in intimate mixture can have a positive effect on spruce wood quality, while incurring relatively small reductions in spruce volume production and also retaining the ecological benefits associated with managing for mixed stands.

Organic–Inorganic Hybrid Materials

According to the IUPAC (International Union of Pure and Applied Chemistry), a hybrid material is that composed of an intimate mixture of inorganic components, organic components, or both types of components which usually interpenetrate on scales of less than 1 μm [...]

History of the Fractional Pollution of Saturn’s Rings from Cassini UVIS

<p><strong>Abstract</strong><br />Over the history of Saturn’s rings, they have been bombarded by exogenous meteoritic material which has altered their composition.  Utilizing our Markov-chain based model for the bombardment of the rings, we can characterize the history of the bombardment of the rings and track the fractional pollution over time.  However, this model does not tell us what the current state of the fractional pollution is, nor does it tell us what the composition of the meteoritic pollutant is.  For that, we can utilize spectroscopic observations from the UVIS instrument that was onboard the Cassini Spacecraft.<br />Utilizing the FUV dataset collected by UVIS, we calculate the current state of the fractional pollution of Saturn’s A, B and C rings by computing best-fits to the observed spectra using Hapke’s model for bidirectional reflectance of an intimate mixture of regolith grains (ice grains plus exogenous grains).  Further, we can test different pollutants to determine which pollutant spectra fits best to the observations.  Our candidate pollutant is cometary material reflectance as measured by the Rosetta spacecraft [5], which we compare against amorphous carbon.<br />Comparing our bombardment model with the fractional pollution calculated from UVIS, allows us to estimate the age of Saturn’s rings, and to gain insight into the history of the rings.</p> <p><br /><strong>1. Bombardment Model Updates</strong><br />We update our bombardment model [1] to include the latest estimates for the exogenous mass flux into the Saturn system [2].  We also compare our results to those presented by Estrada et al. at EPSC/DPS 2019 [6].</p> <p><br /><strong>2. Spectroscopy</strong><br />To determine the current fractional pollution of the rings, we perform a non-linear least-squares fit analysis using a Hapke [3] model for bidirectional reflectance of an intimate mixture of regolith of water-ice and pollutant grains.<br />As Poppe 2016 [7] modeled, we assume that the exogenous material entering the Saturn system originates primarily from the Kuiper belt.  As a proxy for Kuiper belt material spectra, we use the phase dependent spectra of comet 67P/Churyumov–Gerasimenko from the Rosetta Alice instrument [4,5] as our pollutant ring material.  <br />By computing a best-fit Hapke model, using these to material spectra, we can estimate the fractional pollution present in the Rings.</p> <p><br /><strong>3. Summary</strong><br />Our best fit spectra for the A, B and C rings yield a fractional pollution which is then compared to the updated bombardment model simulation in order to understand the history of the rings and their age.</p> <p><br /><strong>References</strong><br />[1] Elliott, J.P., Esposito, L.W.: Regolith depth growth on an icy body orbiting Saturn and evolution of bidirectional reflectance due to surface composition changes, Icarus, Vol. 212.1, pp. 268-274, 2011.<br />[2] Altobelli, N. et al.: Exogenous dust at Saturn observed by CASSINI-CDA, Cassini Science Symposium, 12-17 August 2018, Boulder Colorado, USA, 2018.<br />[3] Hapke, B.: Theory of reflectance and emittance spectroscopy. Cambridge university press, 2012.<br />[4] Stern, S. A., et al.: First extreme and far ultraviolet spectrum of a Comet Nucleus: Results from 67P/Churyumov-Gerasimenko. Icarus, Vol. 256, pp. 117-119, 2015.<br />[5] Feaga, L. M., et al.: Far-UV phase dependence and surface characteristics of comet 67P/Churyumov-Gerasimenko as observed with Rosetta Alice. A&A, Volume 583, 2015<br />[6] Estrada P. R., et al.: Evolution of Saturn’s Rings due to Combined ViscousSpreading and Micrometeoroid Bombardment. EPSC-DPS Joint Meeting, Geneva, 2019.<br />[7] Poppe A. R.: An improved model for interplanetary dust fluxes in the outer Solar System. Icarus, Vol 264, pp 369-386, 2016.</p>

Swelling capacity of mixed talc-like/stevensite layers in white/green clay infillings (“deweylite”/ “garnierite”) from serpentine veins of faulted peridotites, New Caledonia

White (Mg-rich) and green (Ni-rich) clay infillings (“deweylite”/ “garnierite”) found in serpentine veins of faulted peridotite formations from New Caledonia consist of an intimate mixture of fine-grained and poorly ordered 1:1 and 2:1 layer silicates, commonly referred to as non-expandable serpentine-like (SL) and talc-like (TL) minerals. New data on the swelling and shrinking capacity of these layer silicates were gathered from X-ray diffraction (XRD) after saturation of the clay fractions with different cations (Ca2+, Li+, K+), ethylene glycol (EG) solvation, and heat treatments. Simultaneously, layer charge distribution and vacancy density, respectively, were investigated by FTIR spectroscopy on NH4-saturated clay fractions and XRD on Li-saturated clay fractions before and after heating (Hofmann Klemen treatment). Five clay infillings, with dominant 2:1 layer silicates and variable Ni contents, were selected for this study, from a large set of veinlets, according to their swelling capacity. The crystal chemistry of these samples was characterized by FTIR spectroscopy and bulk chemical analyses. The swelling ability of the clay infillings is attributed to the 2:1 layer silicates. It does not seem to be affected by the relative fraction of Mg and Ni in their octahedral sheets. In XRD patterns, the swelling ability is reflected by slight shifts of the basal reflection of the 2:1 layer silicates toward low angles for bulk samples and by splitting of the peak into two contributions for clay fractions saturated with Ca (or Li) and solvated with EG. The split increases with the swelling capacity of the sample. It originates mainly from octahedral-layer charge generated by vacant sites. Such results lead us to consider the 2:1 layer silicates of the infillings as an intimate mixture of non-expandable (TL) and expandable (stevensite) phases. In agreement with previous studies that suggested a contribution of hydrothermal processes in the alteration of serpentine species into 2:1 layer silicates, we propose that the proportion of expandable phases in the clay infillings (or vacancy sites in the octahedral sheets of the 2:1 layer silicates) could be used as an efficient means for assessing the temperature of their formation. Clay infillings mostly made of stevensite would have formed at ambient temperatures, whereas those consisting mainly of non-expandable TL would have formed at higher temperatures.

Did a Complex Carbon Cycle Operate in the Inner Solar System?

Solids in the interstellar medium consist of an intimate mixture of silicate and carbonaceous grains. Because 99% of silicates in meteorites were reprocessed at high temperatures in the inner regions of the Solar Nebula, we propose that similar levels of heating of carbonaceous materials in the oxygen-rich Solar Nebula would have converted nearly all carbon in dust and grain coatings to CO. We discuss catalytic experiments on a variety of grain surfaces that not only produce gas phase species such as CH4, C2H6, C6H6, C6H5OH, or CH3CN, but also produce carbonaceous solids and fibers that would be much more readily incorporated into growing planetesimals. CH4 and other more volatile products of these surface-mediated reactions were likely transported outwards along with chondrule fragments and small Calcium Aluminum-rich Inclusions (CAIs) to enhance the organic content in the outer regions of the nebula where comets formed. Carbonaceous fibers formed on the surfaces of refractory oxides may have significantly improved the aggregation efficiency of chondrules and CAIs. Carbonaceous fibers incorporated into chondritic parent bodies might have served as the carbon source for the generation of more complex organic species during thermal or hydrous metamorphic processes on the evolving asteroid.

Did a Complex Carbon Cycle Operate in the Inner Solar System?

Solids in the interstellar medium consist of an intimate mixture of silicate and carbonaceous grains. Because 99% of silicates in meteorites were reprocessed at high temperatures in the inner regions of the Solar Nebula, we propose that similar levels of heating of carbonaceous materials in the oxygen-rich Solar Nebula would have converted nearly all carbon in dust and grain coatings to CO. We discuss catalytic experiments on a variety of grain surfaces that not only produce gas-phase species such as CH4, C2H6, C6H6, C6H5OH or CH3CN, but also produce carbonaceous solids and fibers that would be much more readily incorporated into growing planetesimals. CO and other more volatile products of these surface mediated reactions were likely transported outwards along with chondrule fragments and small Calcium Aluminum Inclusions (CAIs) to enhance the organic content in the outer regions of the nebula where comets formed. Carbonaceous fibers formed on the surfaces of refractory oxides may have significantly improved the aggregation efficiency of chondrules and CAIs. Carbonaceous fibers incorporated into chondritic parent bodies might have served as the carbon source for the generation of more complex organic species during thermal or hydrous metamorphic processes on the evolving asteroid.

A Case of Nasal Angiomyolipoma in Young Man

Angiomyolipoma is a benign tumor that is composed of adipose tissue, blood vessels and smooth muscle. The kidney is the most common site for this tumor. Although extrarenal angiomyolipoma is rarely found in areas other than the kidney, it has been observed in other organs such as liver, heart, mediastinum, spermatic cord, vaginal wall, oral cavity, and so on. Angiomyolipoma in the nasal cavity especially, has been very rarely reported in literature. Furthermore, nasal angiomyolipoma is mostly found in middle aged or old men. In this case, angiomyolipoma was found in a 29-year-old male patient who was the youngest of the reported cases. He complained of nasal obstruction and physical examination revealed a 1.5 cm sized mass in the left posterior part of the nasal septum. The mass was composed of an intimate mixture of mature fat, smooth muscle cells, and thick walled varying sized blood vessels histopathologically coinciding with angiomyolipoma. It was removed via endoscopic surgery without complications.

MCT CLASSIFICATION FOR COMPACTED MIXTURES OF SOIL-STEEL SLAG-FLY ASH FOR APPLICATION IN FOREST ROADS

ABSTRACT This work aimed to evaluate the potential application of a stabilizer derived from the intimate mixture of powder electric arc furnace oxidizing slag and fly ash, aiming at the improvement of soil engineering properties for enforcement purposes on forest roads. This evaluation was undertaken by means of an experimental program of laboratory tests to classify soils and mixtures of these with the proposed stabilizer according to the MCT (Miniature, Compacted, Tropical) methodology. The proportions of waste mixtures were 10% and 20% of the total dry mass of soil-waste combinations and percentages of ground steel slag were 75%, 87.5% and 100% relative to total dry mass of waste mixtures. It was shown the potential to technically enable the use of steel waste in the composition of forest roads, emphasizing the relevance of the proposal in meeting the need of steel companies to confer a sustainable destination for the waste and the need of forest companies to meet, with low-cost materials, the significant demands of their unpaved road network.

Dynamic nuclear polarization of a glassy matrix prepared by solid state mechanochemical amorphization of crystalline substances

“Solvent-free” co-milling effectively produces an intimate mixture of the solid substrate and the radical species for performing DNP.