1,354,378 research outputs found
Spectrophotometric methods for lignin and cellulose in forest soils as predictors for humic substances
No full textThe origin and fate of humus, a soil organic matter fraction that is most resistant to decomposition, are not yet completely understood. Humus derives mainly from plant structural components; that is, lignin and cellulose, together with several other primary and secondary compounds. There are several methods to estimate lignin and cellulose in plant material; however, the applications to soil are limited and usually complicated and expensive. Conversely, humus can be estimated in soil by chemical titration methods, which estimate the carbon linked to humic and fulvic acids (HAC and FAC). Therefore, we carried out analyses that aimed to compare, within beech forest soils, spectrophotometric data for lignin and cellulose with those of HAC and FAC. We used soil samples from six different beech woods in Italy, sampling in four layers from 0–5 to 30–40 cm. The relations between spectrophotometric cellulose and lignin and HAC and FAC were tested by linear mixed models. Our results showed that both lignin and cellulose were significant predictors for HAC and FAC, even if cellulose had a larger conditional coefficient of determination (R2 c). The best fit was between cellulose and the sum of HAC and FAC (R2 c = 0.675). Our novel approach proved that spectrophotometric lignin and cellulose provide reliable results in both organic and mineral beech forest soils, even though lignin had a greater random variation than cellulose. Thus, spectrophotometric lignin and cellulose provide reliable and rapidly obtained predictors of humic substances in beech forest soils, with appropriate conversion factors to estimate HAC and FAC. Highlights: Humic substances are of pivotal importance in the global carbon cycle. There is a need for simple and rapid methods to estimate humic substances. Spectrophotometric methods provide fast results for cellulose and lignin in soils. Lignin and cellulose function as good predictors for humic substances in forest soil
A bill to be entitled an act relating to in memory of Danise Blalock of Mount Pleasant.
No full textConcurrent resolution introduced by the Texas House of Representatives and Senate relating to in memory of Danise Blalock of Mount Pleasant
Leaf traits of European Beech along altitudinal gradients on the Italian Apennines: relationships wiith climate and litter stock
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From Soil to Bird Community: a guild-based approach to investigate relationships between forest variables in a small-scale ecosystem
No full textSpectrophotometric methods for lignin and cellulose in forest soils as predictors for humic substances
No full textSummary: The origin and fate of humus, a soil organic matter fraction that is most resistant to decomposition, are not yet completely understood. Humus derives mainly from plant structural components; that is, lignin and cellulose, together with several other primary and secondary compounds. There are several methods to estimate lignin and cellulose in plant material; however, the applications to soil are limited and usually complicated and expensive. Conversely, humus can be estimated in soil by chemical titration methods, which estimate the carbon linked to humic and fulvic acids (HAC and FAC). Therefore, we carried out analyses that aimed to compare, within beech forest soils, spectrophotometric data for lignin and cellulose with those of HAC and FAC. We used soil samples from six different beech woods in Italy, sampling in four layers from 0–5 to 30–40 cm. The relations between spectrophotometric cellulose and lignin and HAC and FAC were tested by linear mixed models. Our results showed that both lignin and cellulose were significant predictors for HAC and FAC, even if cellulose had a larger conditional coefficient of determination (R2c). The best fit was between cellulose and the sum of HAC and FAC (R2c= 0.675). Our novel approach proved that spectrophotometric lignin and cellulose provide reliable results in both organic and mineral beech forest soils, even though lignin had a greater random variation than cellulose. Thus, spectrophotometric lignin and cellulose provide reliable and rapidly obtained predictors of humic substances in beech forest soils, with appropriate conversion factors to estimate HAC and FAC. Highlights: Humic substances are of pivotal importance in the global carbon cycle. There is a need for simple and rapid methods to estimate humic substances. Spectrophotometric methods provide fast results for cellulose and lignin in soils. Lignin and cellulose function as good predictors for humic substances in forest soils
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
THE EFFECT OF HIV-1 IN DECREASING MITOCHONDRIAL DNA IN PERIPHERAL BLOOD MONONUCLEAR CELLS OVERCOMES THE TOXIC EFFECT OF ANTIRETROVIRAL THERAPY (ART)
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