Recent works show that organic matter accumulation in some soils from coastal Antarctica is highe... more Recent works show that organic matter accumulation in some soils from coastal Antarctica is higher than previously expected. The objective of the present work was to estimate the organic C stocks for soils from maritime Antarctica. Cryosols from subpolar desert landscapes presented the lowest organic C stocks. Ornithogenic soils are the most important C reservoirs in terrestrial ecosystems in this
Structural features of the acidic, highly substituted glycanoxylan (LCP; 87% yield) from the gum ... more Structural features of the acidic, highly substituted glycanoxylan (LCP; 87% yield) from the gum exudate of the palm, Livistona chinensis, family Arecaceae, were determined. It had [α]D −30°, Mw 1.9×105 and a polydispersity ratio Mw/Mn of ∼1.0. Acid hydrolysis gave rise to Rha, Fuc, Ara, Xyl, and Gal, in a 1:6:46:44:3 molar ratio, and 12% of uronic acid was present.
... 2. Materials and methods. 2.1. Collection of gum exudate and isolation of its polysaccharide ... more ... 2. Materials and methods. 2.1. Collection of gum exudate and isolation of its polysaccharide (SRP). ... 2.2. Investigation of low molecular weight material in the gum exudate. The exudate (30 g) was immersed in H 2 O (1.0 L) for 16 h and gum then triturated in a blender. ...
The polysaccharide (VTh) extracted with water from the gum exudate of the trunk Vochysia thyrsoid... more The polysaccharide (VTh) extracted with water from the gum exudate of the trunk Vochysia thyrsoidea gave a solution of high viscosity and was homogeneous, with Mw 92.5×103 and dn/dc=0.212. Partial hydrolysis gave a main chain of →4)-β-d-GlcpA-(1→2)-α-d-Manp-(1→ repeating groups. Since VTh contained 24% GlcA, neither its monosaccharide ratio (GC–MS of alditol acetates) nor methylation results were accurate. It was therefore
There exists many kinds of technologies and sensors for measuring temperature, however, two of th... more There exists many kinds of technologies and sensors for measuring temperature, however, two of the most common types of sensors are thermocouples and thermistors. These sensors have dynamical response to a temperature change in the surroundings, and also have nonlinearities in the mapping between temperature and electrical signal at their output. When dealing with the characterization of thermal hysteretic devices, the nonlinear dynamical response of the temperature sensor may cause a severe distortion in the shape of the hysteresis curve. In this paper is presented a nonlinear inverse filtering structure using an artificial neural network for distortion correction in vanadium dioxide films thermal hysteresis measurements. A time-delay neural network is applied to obtain an approximation of the true hysteretic characteristics, removing the undesired distortion. The network training is performed using experimentally measured data. A comparison is presented between the neural method and a parametric estimation.
Recent works show that organic matter accumulation in some soils from coastal Antarctica is highe... more Recent works show that organic matter accumulation in some soils from coastal Antarctica is higher than previously expected. The objective of the present work was to estimate the organic C stocks for soils from maritime Antarctica. Cryosols from subpolar desert landscapes presented the lowest organic C stocks. Ornithogenic soils are the most important C reservoirs in terrestrial ecosystems in this
Structural features of the acidic, highly substituted glycanoxylan (LCP; 87% yield) from the gum ... more Structural features of the acidic, highly substituted glycanoxylan (LCP; 87% yield) from the gum exudate of the palm, Livistona chinensis, family Arecaceae, were determined. It had [α]D −30°, Mw 1.9×105 and a polydispersity ratio Mw/Mn of ∼1.0. Acid hydrolysis gave rise to Rha, Fuc, Ara, Xyl, and Gal, in a 1:6:46:44:3 molar ratio, and 12% of uronic acid was present.
... 2. Materials and methods. 2.1. Collection of gum exudate and isolation of its polysaccharide ... more ... 2. Materials and methods. 2.1. Collection of gum exudate and isolation of its polysaccharide (SRP). ... 2.2. Investigation of low molecular weight material in the gum exudate. The exudate (30 g) was immersed in H 2 O (1.0 L) for 16 h and gum then triturated in a blender. ...
The polysaccharide (VTh) extracted with water from the gum exudate of the trunk Vochysia thyrsoid... more The polysaccharide (VTh) extracted with water from the gum exudate of the trunk Vochysia thyrsoidea gave a solution of high viscosity and was homogeneous, with Mw 92.5×103 and dn/dc=0.212. Partial hydrolysis gave a main chain of →4)-β-d-GlcpA-(1→2)-α-d-Manp-(1→ repeating groups. Since VTh contained 24% GlcA, neither its monosaccharide ratio (GC–MS of alditol acetates) nor methylation results were accurate. It was therefore
There exists many kinds of technologies and sensors for measuring temperature, however, two of th... more There exists many kinds of technologies and sensors for measuring temperature, however, two of the most common types of sensors are thermocouples and thermistors. These sensors have dynamical response to a temperature change in the surroundings, and also have nonlinearities in the mapping between temperature and electrical signal at their output. When dealing with the characterization of thermal hysteretic devices, the nonlinear dynamical response of the temperature sensor may cause a severe distortion in the shape of the hysteresis curve. In this paper is presented a nonlinear inverse filtering structure using an artificial neural network for distortion correction in vanadium dioxide films thermal hysteresis measurements. A time-delay neural network is applied to obtain an approximation of the true hysteretic characteristics, removing the undesired distortion. The network training is performed using experimentally measured data. A comparison is presented between the neural method and a parametric estimation.
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