Mass Loss

Although USLE and RUSLE have been adjusted and validated for use in Uruguay, soil mass losses should be expressed in terms of soil productivity or land value losses, in order to guide management decision-making, and assess its impact in productive and economic terms. Procedures to this have been published (e.g. EPIC), but are not yet validated in Uruguay. Being extensive animal production, based on natural pastures grazing, the main agricultural activity in Uruguay (about 80% of the land), soil productivity loss due to soil erosion should be better expressed in these terms. Uruguay has a system of soil productivity assessment at individual farm level, that expresses soil potential animal production of beef and wool as a quantitative Productivity Index (PI), referred to the national average (PI=100). This system was developed 25 years ago overlapping soil maps at 1:20,000 scale, with the official records of production of 721 administrative divisions of the country, and the available ...

Information about the times of thermal breakthrough and subsequent rates of thermal drawdown in enhanced geothermal systems (EGS) is necessary for reservoir management, designing fracture stimulation and well drilling programs, and forecasting economic return. Thermal breakthrough in heterogeneous porous media can be estimated using conservative tracers and assumptions about heat transfer rates; however, tracers that undergo temperature-dependent changes can provide more detailed information about the thermal profile along the flow path through the reservoir. To be effectively applied, the thermal reaction rates of such temperature sensitive traces must be well characterized for the range of conditions that exist in geothermal systems. Reactive tracers proposed in the literature include benzoic and

Thermal decomposition of precursor xerogels for TiO2, obtained by gelling of acetylacetonate-modified titanium(IV) tetraisopropoxide (prepared at Ti-alkoxide:acetylacetone molar ratios of 1:1 (Ti-1) and 1:2 (Ti-2)) in boiling 2-methoxyethanol, was monitored by simultaneous TG/DTA/EGA-MS and EGA-FTIR measurements. Thermal degradation processes of Ti-1 and Ti-2 in the temperature range of 30–700°C consist of six mass loss steps, the total mass loss being 46.3% and 54.4%, respectively. EGA by FTIR and MS revealed release of H2O below 120°C; followed by evolution of acetone and acetic acid between approximately 100 and 320°C, and that of CO2 up to 560°C. Acetylacetone is evolved to a significant extent from sample Ti-2 at 120–200°C.

Calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world. Calving rates can increase dramatically in response to increases in velocity and/or retreat of the glacier margin, with important implications for sea level change. Despite their importance, calving and related dynamic processes are poorly represented in the current generation of ice sheet models. This is largely because understanding the 'calving problem' involves several other long-standing problems in glaciology, combined with the difficulties and dangers of field data collection. In this paper, we systematically review different aspects of the calving problem, and outline a new framework for representing calving processes in ice sheet models. We define a hierarchy of calving processes, to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events. The first-order control on calving is the strain rate arising from spatial variations in velocity (particularly sliding speed), which determines the location and depth of surface crevasses. Superimposed on this first-order process are second-order processes that can further erode the ice margin. These include: fracture propagation in response to local stress imbalances in the immediate vicinity of the glacier front; undercutting of the glacier terminus by melting at or below the waterline; and bending at the junction between grounded and buoyant parts of an ice tongue. Calving of projecting, submerged 'ice feet' can be regarded as a third-order process, because it is paced by first- or second-order calving above the waterline. First-order calving can be represented in glacier models using a calving criterion based on crevasse depth, which is a function of longitudinal strain rate. Modelling changes in terminus position and calving rates thus reduces to the problem of determining the ice geometry and velocity distribution. Realistic solutions to the problem of modelling ice flow therefore depend critically on an appropriate choice of sliding law. Models that assume that basal velocities are controlled by basal drag can replicate much of the observed behaviour of calving glaciers with grounded termini, but an important limitation is that they cannot be used to model floating glacier termini or ice shelves. Alternative sliding laws that parameterise drag from the glacier margins provide more flexible and robust ways of representing calving in ice sheet models. Such models can explain a remarkable range of observed phenomena within a simple, unifying framework, including: downglacier increases in velocity and strain rates where basal and/or lateral drag diminishes; flow acceleration in response to thinning through time; the tendency for glaciers to stabilise at 'pinning points' in relatively shallow water or fjord narrowings; the constraints on ice shelf stability; and the contrasts in calving rates between tidewater and freshwater calving glaciers. Many unresolved issues remain, however, including the role played by the removal of backstress in the acceleration of retreating calving glaciers, and the controls on melting at and below the waterline.

The aim of this paper is to assess the performance of self-compacting glass concrete (SCGC) after exposure to four elevated temperatures of 300 °C, 500 °C, 600 °C and 800 °C. The influence of curing conditions on the high temperature performance of SCGC was also investigated. For each curing regime, five SCGC mixtures were prepared with recycled glass (RG) which was used to replace natural fine aggregate at the level of 0%, 25%, 50%, 75% and 100%. After exposure to the elevated temperatures, concrete mass loss, density, water porosity, ultrasonic pulse velocity (UPV) and water sorptivity were determined and then a compressive strength test was conducted. The test results indicate that regardless of the exposure temperature, all the water cured specimens had higher residual strengths and mass losses while the water porosity and water sorptivity values were lower as compared to the corresponding air cured specimens. The incorporation of RG in the concrete mixes helped to maintain the concrete properties after the high temperature exposure due to the melting and resolidification of the recycled glass in the concrete matrix.

Sapwood samples of Pinus pinaster wood were treated with a 70% furfuryl alcohol mixture. Weight percent gain (WPG), equilibrium moisture content, dimensional stability, MOE, bending strength, hardness, density and durability were determined. WPG was on average 38%. Equilibrium moisture content decreased more than 40%. Dimensional stability increased reaching an ASE of 45%. MOE was little affected by the treatment but bending strength increased by about 6%. Hardness increased by about 50%, and density by 37%. Mass loss due to Postia placenta and Coniophora puteana decreased by 96% and 86%, respectively. Furfurylation of Pinus pinaster wood shows an interesting potential to improve the wood quality for solid timber products. Kiefernsplintholzproben (Pinus pinaster) wurden mit einer 70% Furfurylalkohol-Mischung behandelt und die prozentuale Massezunahme (WPG), die Gleichgewichtsfeuchte, die Dimensionsstabilität, der Elastizitätsmodul, die Biegefestigkeit, die Härte, die Dichte und die Dauerhaftigkeit wurden bestimmt. Die prozentuale Massezunahme lag im Durchschnitt bei 38%. Die Gleichgewichtsfeuchte nahm mehr als 40% ab. Die Dimensionsstabilität nahm zu und erreichte ein Quellresistenzvermögen (ASE) von 45%. Die Behandlung hatte nur wenig Einfluss auf den Elastizitätsmodul, während die Biegefestigkeit um 6% zunahm. Die Härte erhöhte sich um ca. 50% und die Dichte um 37%. Der Masseverlust durch Postia placenta und Coniophora puteana ging um 96% bzw. 86% zurück. Die Furfurylierung von Pinus pinaster Holz zeigt ein hohes Potential zur Verbesserung der Holzqualität von Massivholzprodukten.

The kinetics of the chlorination of gallium oxide in chlorine atmosphere was studied between 650 °C and 800 °C. The calculations of the Gibbs standard free energy variation with temperature for the reaction Ga2O3(S)+3Cl2 (g)→2GaCl3(g)+1.5O2 (g) show that direct chlorination is favorable above 850 °C. Thermogravimetric experiments were performed under isothermal and nonisothermal conditions. The effect of temperature, gas flow rate, and Cl2 partial pressure were studied. The solids were characterized by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The nonisothermal results showed that chlorination of Ga2O3 starts at approximately 650 °C, with a mass loss of 50 pct at 850 °C. The isothermal results between 650 °C and 800 °C indicated that the reaction rate increased with temperature. The correlation of the experimental data with different solid-gas reaction models showed that the results are adequately represented by the model proposed by Shieh and Lee: X=1−{1−b 22[b 21t+e −b 21t−1]}1/(1−γ). From this model, it was found that the rate of reaction for the chlorination of Ga2O3 is of the order 0.68 with respect to Cl2 and the activation energy is 113.23 kJ/mol. On the other hand, the order of the activation rate of the interface surface is 0.111 with respect to Cl2 and its activation energy is 23.81 kJ/mol.

The main objective of this study was to compare methods for mass loss evaluation in green coffee to water content determination by Karl Fischer titration (KFT). The following methodologies were tested: (i) ISO 6673 (oven drying at 105 °C for 16 h); (ii) the reference method employed by the Brazilian Agriculture Ministry (oven drying at 105 °C for 24 h)—BRAMw, employing whole beans and BRAMg, employing ground beans; and (iii) infrared drying (IRD). Reference oven drying methodologies ISO 6673 and BRAMw presented results statistically equivalent (p>0.05p>0.05) to those from KFT in the moisture content range that is of interest for green coffee commercialization (8–13 g/100 g), whereas IRD results were lower than those for KFT. ISO 6673 and BRAMw also presented the highest values of correlation coefficients to KFT. Differences in moisture content determination became more significant for lower moisture content values (4–7 g/100 g), probably due to loss of organic volatile substances during drying and occurrence of moisture loss during sample grinding.

... inserting (Moore & Hoseney, 1986). Oven rise is assessed by loaf height tracker, assuming it is uniaxial, a reasonable assumption for tin-moulded breads (Kilborn, Preston, & Kubota, 1990). This measurement is important since ...