Artificial neural network analysis of laboratory and in situ spectra for the estimation of macronutrients in soils of Lop Buri (Thailand)

Reflectance spectrometry is an emerging and non-destructive detection technique bearing fast, cheap, and accurate results compared with conventional assessments. Most field and laboratory-based spectrometers are restricted to VNIR (visible–near-infrared). However, soils fail to show well-defined narrow absorption bands in this region. This obstructs the use of curve feature as a diagnostic criterion for soil nutrient predictions. In this paper artificial neural network (ANN) is implemented to estimate soil organic matter, phosphorous, and potassium from the VNIR spectrum (400–1100 nm). Macronutrients were modelled from 41 bare soil reflectances of Lop Buri province, Thailand. Neurons were trained from 7 bandwidth categories derived from laboratory-based StellarNet spectroradiometer and in situ photometer. Satisfactory results were attained and compared across different synthesised bandwidths. Models exhibited slightly better estimates from the laboratory than in situ spectra, and from narrower than broader bandwidths. Widening bandwidth corresponds with attenuated predictive powers, coupled with rising errors. Cross validation of models yielded acceptable correlations. The strength of models confirmed the capability of ANN to estimate macronutrients by solving difficulties incurred from high cross-channel correlations prevailing in conventional statistical techniques.

Metabolism of D-[1-13C]glucose in livers of Meriones unguiculatus infected with Echinococcus multilocularis

Following administration of [1-13C]glucose, sequential 13C nuclear magnetic resonance (NMR) in situ spectra were obtained from the liver of uninfected jirds (Meriones unguiculatus) and those infected with Echinococcus multilocularis over a period of 2 h. Quantitative evaluation of the flow of labelled carbon through the liver at 80 and 120 min after glucose administration revealed that although the percentage of labelled glucose utilized by the liver was the same for both groups, glycogen synthesis differed. At both times, the livers of infected animals had incorporated a smaller percentage of the [1-13C]glucose into glycogen labelled at C1 and a larger percentage into the C6 position of glucose/glycogen. In another experiment, identical with respect to the substrate administered, NMR analysis of perchloric acid extracts revealed that the livers of infected animals had lower concentrations of labelled glucose and glycogen and higher concentrations of labelled alanine and lactate than those of uninfected controls. Concentration differences were also noted for some of the unlabelled metabolites. Echinococcus multilocularis cysts contained the same labelled metabolites as the livers but the concentration of lactate was much higher. Parasite cysts also contained labelled acetate.