Douglas D. Archibald

Decomposition of the finest root branching orders : linking belowground dynamics to fine-root function and structure

Root turnover is fastest in the finest roots of the root system (first root order). Additionally, tissue chemistry varies among even the finest root orders and between white roots and older, pigmented roots. Yet the effects of pigmentation and order on root decomposition have rarely been examined. We separated the first four root orders (all <1 mm) of four temperate tree species into three classes: white first- and second-order roots; pigmented first- and second-order roots; and pigmented third- and fourth-order roots. Roots were enclosed in litterbags and buried under their own and under a common species canopy in a 34-year-old common garden in Poland. When comparing decomposition of different root orders over 36 months, pigmented third- and fourth-order roots with a higher C:N ratio decomposed more rapidly, losing 20–40% of their mass, than pigmented first- and second-order roots, which lost no more than 20%. When comparing decomposition of roots of different levels of pigmentation within the same root ...

Quantification of cellulose nanowhiskers sulfate esterification levels.

Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, combustion gas analysis and N(2) adsorption were used to quantify the degree of desulfation of cellulose nanowhiskers (CNWs). CNWs were produced by hydrolyzing cotton cellulose with sulfuric acid or hydrochloric acid. Hydrochloric acid treatment did not result in any cellulose chemical modification. Hydrolysis using H(2)SO(4) introduced sulfate groups onto the cellulose surface. Our results indicate that commercial cotton cellulose as received contained sulfur. The sulfur content of H(2)SO(4)-prepared CNWs was higher than that exhibited by the original cellulose due to the esterification process. Two desulfation methods, acid-catalyzed and solvolytic desulfation, have been explored to remove the sulfate groups. Neither desulfation method examined removed the sulfate groups from H(2)SO(4)-prepared CNWs completely. An estimation of surface sulfate esterification levels was made based on a model of the cellulose structure and available surface area of CNWs. According to these models, more than one third of hydroxyl groups on the surface were substituted by sulfate.

Relationship of Sphinganine Analog Mycotoxin Contamination in Maize Silage to Seasonal Weather Conditions and to Agronomic and Ensiling Practices

ABSTRACT Sphinganine analog mycotoxins (SAMs) are reported in maize and maize based feeds. Our objectives were to detect and quantify fumonisins B(1) and B(2) and Alternaria toxins (AAL toxins) AAL-TA and AAL-TB and determine how agronomic practices, weather conditions, and ensiling affected the occurrence and levels in maize silage. Silage was collected at harvest and after ensiling in 2001 and 2002 from 30 to 40 dairies, representing four regions in Pennsylvania. SAMs were quantified using high pressure liquid chromatography (HPLC) with fluorescence detection and high pressure liquid chromatography-mass spectrometry HPLC-MS. The average concentrations and ranges were as follows: fumonisin B(1) 2.02 mug/g (0.20 to 10.10), fumonisin B(2) 0.98 mug/g (0.20 to 20.30), AAL-TA 0.17 mug/g (0.20 to 2.01), and AAL-TB 0.05 mug/g (0.03 to 0.90). Fumonisin B(1) was the most frequently detected toxin (92%) in all samples, followed by fumonisin B(2) (55%), AAL-TA (23%), and -TB (13%). Temperature during maize development was positively correlated with fumonisin occurrence and levels and negatively with AAL-TA, while moisture events were negatively correlated with fumonisins and positively with AAL-TA. Fumonisin levels were higher in silage harvested at later developmental stages (dough through physiological maturity). Ensiling did not affect toxin concentration nor did agronomic practices (tillage system, inoculant use, or silo type) or silage characteristics (dry matter, pH, or organic acid concentration). This is the first report of AAL-TB in silage and on factors that affect SAM frequency and levels in maize silage.

NIR-FT/Raman spectroscopy for nutritional classification of cereal foods

ABSTRACT The classification of cereals using near-infrared Fourier transform Raman (NIR-FT/Raman) spectroscopy was accomplished. Cereal-based food samples (n = 120) were utilized in the study. Ground samples were scanned in low-iron NMR tubes with a 1064 nm (NIR) excitation laser using 500 mW of power. Raman scatter was collected using a Ge (LN2) detector over the Raman shift range of 202.45~3399.89 cm-1. Samples were classified based on their primary nutritional components (total dietary fiber [TDF], fat, protein, and sugar) using principle component analysis (PCA) to extract the main information. Samples were classified according to high and low content of each component using the spectral variables. Both soft independent modeling of class analogy (SIMCA) and partial least squares (PLS) regression based classification were investigated to determine which technique was the most appropriate. PCA results suggested that the classification of a target component is subject to interference by other components ...

Determination of Sulfate Esterification Levels in Cellulose Nanocrystals by Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy

Cellulose nanocrystals were produced by hydrolyzing cotton cellulose with high concentration sulfuric acid. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used as a simple method to quantify the sulfate esterification levels of cellulose nanocrystals(CNCs) with different post treatments. Understanding the surface chemistry of cellulose is critical for creating realistic model systems for studying lignocellulose assembly. Cellulose nanocrystals prepared by a less efficient hydrochloric acid treatment, which do not have the sulfate content, were used as the zero sulfate standards. Dextran sulfate was added to the zero standards in order to create calibration curves. Our results indicate that both post hydrochloric acid and pyridine treatment after the sulfuric acid hydrolysis process did not remove the sulfate groups on the cellulose nanocrystals effectively, in contract to previously published data. Our data suggests that this method did not work well on cellulose and only cellulose pyridinium salts were obtained. This is under further study.