Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010
The tensile fatigue behavior of long aligned sisal fiber reinforced cement composites was investi... more The tensile fatigue behavior of long aligned sisal fiber reinforced cement composites was investigated. The fatigue behavior was examined in terms of the stress versus cycles and stress–strain hysteresis behavior of the composites. Composites were tested at stress levels ranging between 4 and 9.8MPa which represent approximately 30–80% of the monotonic ultimate tensile strength. The composites did not fail in
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009
The tensile fatigue behavior of individual sisal fibers was investigated. The fatigue behavior wa... more The tensile fatigue behavior of individual sisal fibers was investigated. The fatigue behavior was examined in terms of the stress versus cycles and stress–strain hysteresis behavior of the fibers. Fibers were tested at stress levels ranging between 80 and 400MPa. The sisal fibers did not fatigue below a maximum fatigue level of 320. The stress versus cycles curve was normalized
Failures in stability and COD removal performance often occurred in full-scale anaerobic reactors... more Failures in stability and COD removal performance often occurred in full-scale anaerobic reactors treating the evaporator condensate from a sulphite pulp mill due to substrate inhibition and occasional contaminations with red liquor (wood cooking liquor). With this work, the beneficial effect provided by the continuous addition of an external carbon source (sugarcane molasses) on the overall performance and stability of the biological process was evaluated. With a moderate addition of molasses the inhibition was mitigated which led to an increase of the COD removal rate from 52% to 77% and a methane production increase from 460 to 1650mld(-1) at an organic loading rate of 2.61g CODl(-1)d(-1). A similar conclusion can be drawn for the case when contamination with red liquor occurs. These results suggest that sugarcane molasses addition may be regarded as a low-cost operational strategy for the anaerobic treatment of sulphite evaporator condensate.
Eucalyptus grandis wood samples decayed by white- and brown-rot fungi were cooked at 180°C for 5 ... more Eucalyptus grandis wood samples decayed by white- and brown-rot fungi were cooked at 180°C for 5 to 100 min with methanol/water (78:22 v/v) containing 25 mM of CaCl2 and 25 mM MgSO4. Mathematical models for describing organosolv pulping kinetics of the fungally pretreated samples were developed to estimate delignification constants, and also rate constants for xylan and wood mass solubilization.
ABSTRACT Six lignins were used to obtain granular controlled release matrix formulations of the h... more ABSTRACT Six lignins were used to obtain granular controlled release matrix formulations of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). The water insoluble lignins were sourced from sugar cane (Saccharum officinarum) bagasse and Eucalyptus sp. and Pinus sp. woods. Each lignin was characterized by its functional groups and molecular weight distributions. The formulations were prepared by melting the 2,4-D and mixing in the lignins individually and then granulating (to 0.7−1.0 mm) the glassy matrix. Release rates determined in static water were correlated to a diffusion-controlled mechanism according to the square root of time. Principal component regression of the slopes of these lines showed that these depend inversely on the molecular weight and the total and aliphatic hydroxyls of the lignins. For the other functional groups (aromatic hydroxyls, methoxyls, and carbonyls), the higher their contents, the higher the diffusion and release rates. Keywords: Controlled-release; 2,4-D; lignin; chemical structure; release rates
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010
The tensile fatigue behavior of long aligned sisal fiber reinforced cement composites was investi... more The tensile fatigue behavior of long aligned sisal fiber reinforced cement composites was investigated. The fatigue behavior was examined in terms of the stress versus cycles and stress–strain hysteresis behavior of the composites. Composites were tested at stress levels ranging between 4 and 9.8MPa which represent approximately 30–80% of the monotonic ultimate tensile strength. The composites did not fail in
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009
The tensile fatigue behavior of individual sisal fibers was investigated. The fatigue behavior wa... more The tensile fatigue behavior of individual sisal fibers was investigated. The fatigue behavior was examined in terms of the stress versus cycles and stress–strain hysteresis behavior of the fibers. Fibers were tested at stress levels ranging between 80 and 400MPa. The sisal fibers did not fatigue below a maximum fatigue level of 320. The stress versus cycles curve was normalized
Failures in stability and COD removal performance often occurred in full-scale anaerobic reactors... more Failures in stability and COD removal performance often occurred in full-scale anaerobic reactors treating the evaporator condensate from a sulphite pulp mill due to substrate inhibition and occasional contaminations with red liquor (wood cooking liquor). With this work, the beneficial effect provided by the continuous addition of an external carbon source (sugarcane molasses) on the overall performance and stability of the biological process was evaluated. With a moderate addition of molasses the inhibition was mitigated which led to an increase of the COD removal rate from 52% to 77% and a methane production increase from 460 to 1650mld(-1) at an organic loading rate of 2.61g CODl(-1)d(-1). A similar conclusion can be drawn for the case when contamination with red liquor occurs. These results suggest that sugarcane molasses addition may be regarded as a low-cost operational strategy for the anaerobic treatment of sulphite evaporator condensate.
Eucalyptus grandis wood samples decayed by white- and brown-rot fungi were cooked at 180°C for 5 ... more Eucalyptus grandis wood samples decayed by white- and brown-rot fungi were cooked at 180°C for 5 to 100 min with methanol/water (78:22 v/v) containing 25 mM of CaCl2 and 25 mM MgSO4. Mathematical models for describing organosolv pulping kinetics of the fungally pretreated samples were developed to estimate delignification constants, and also rate constants for xylan and wood mass solubilization.
ABSTRACT Six lignins were used to obtain granular controlled release matrix formulations of the h... more ABSTRACT Six lignins were used to obtain granular controlled release matrix formulations of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). The water insoluble lignins were sourced from sugar cane (Saccharum officinarum) bagasse and Eucalyptus sp. and Pinus sp. woods. Each lignin was characterized by its functional groups and molecular weight distributions. The formulations were prepared by melting the 2,4-D and mixing in the lignins individually and then granulating (to 0.7−1.0 mm) the glassy matrix. Release rates determined in static water were correlated to a diffusion-controlled mechanism according to the square root of time. Principal component regression of the slopes of these lines showed that these depend inversely on the molecular weight and the total and aliphatic hydroxyls of the lignins. For the other functional groups (aromatic hydroxyls, methoxyls, and carbonyls), the higher their contents, the higher the diffusion and release rates. Keywords: Controlled-release; 2,4-D; lignin; chemical structure; release rates
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