The scientific understanding of the molecular size and shape of humic substances (HS) is critically reviewed. The traditional view that HS are polymers in soil is not substantiated by any direct evidence but is assumed only on the basis of laboratory experiments with model molecules and unwarranted

The supramolecular structure of humic substances

The scientific understanding of the molecular structure of humic substances is critically reviewed here. The traditional view that humic substances are polymers in soil is not substantiated by any direct evidence but only assumed on the basis of laboratory experiments with model molecules and unwarranted results by incorrectly applying either analytical procedures or mathematical treatments developed for purified and undisputed biopolymers. A large body of evidence instead shows an alternative understanding of the conformational nature of humic substances which should be regarded as supramolecular associations of self-assembling heterogeneous and relatively small molecules deriving from the degradation and decomposition of dead biological material. A major aspect of the humic supramolecular structure is that it is predominantly stabilized by weak dispersive forces instead of covalent linkages. Hydrophobic (van der Waals, π-π, CH-π) and hydrogen bonds are responsible for the apparent large molecular size of humic substances, the former becoming more important with the increase of pH. Such novel description of humic substances structure better accounts for their essential role in providing and maintaining soil physical and chemical quality and their reactivity towards pesticides and other environmental soil contaminants. This innovative understanding of the nature of humic substances implies a further development of the science and technology for the control of the chemistry and dynamics of natural organic matter in the soil and the environment.

The supramolecular structure of humic substances: A novel understanding of humus chemistry and implications in soil science

Purpose: Fatty liver disease (FLD) is an increasing prevalent disease that can be reversed if detected early. Ultrasound is the safest and ubiquitous method for identifying FLD. Since expert sonographers are required to accurately interpret the liverultrasoundimages, lack of the same will result in interobserver variability. For more objective interpretation, high accuracy, and quick second opinions, computer aided diagnostic(CAD) techniques may be exploited. The purpose of this work is to develop one such CAD technique for accurate classification of normal livers and abnormal livers affected by FLD. Methods: In this paper, the authors present a CAD technique (called Symtosis) that uses a novel combination of significant features based on the texture, wavelet transform, and higher order spectra of the liverultrasoundimages in various supervised learning-based classifiers in order to determine parameters that classify normal and FLD-affected abnormal livers. Results: On evaluating the proposed technique on a database of 58 abnormal and 42 normal liverultrasoundimages, the authors were able to achieve a high classification accuracy of 93.3% using the decision tree classifier. Conclusions: This high accuracy added to the completely automated classification procedure makes the authors' proposed technique highly suitable for clinical deployment and usage.

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Data mining framework for fatty liver disease classification in ultrasound: a hybrid feature extraction paradigm.

Full Length Article: An information fusion based method for liver classification using texture analysis of ultrasound images

Summary

Humic substances were investigated by both UV and visible absorption spectroscopic methods with special emphasis on their macromolecular characteristics. The spectral ranges examined were 200–350 nm and 350–700 nm. Conclusions were drawn on the basis of absorption intensities in optical density (O.D.) vs. wavelength (λ) curves, slopes of log O.D. vs. log λ plots, nature of shoulders in the 250–270 nm region, and E4/E6 ratios. As macromolecular characteristics are expected to be dependent on the medium, studies were carried out at different pH values as well as at different neutral salt concentrations, the two major parameters influencing the soil environment.



It was noted that with increasing neutral electrolyte concentrations, the particle size decreased, probably due to the coiling of the macromolecule.



On increasing the pH from 6.5 to 9.5, the particle size increased slightly, possibly because of partial association through homolytic bonding. At pH 3.5 (with FA only), the degree of association was greater than that at pH 9.5. However, here association occurred by a different mechanism, that of intermolecular hydrogen bonding. At pH 2.0 (with FA only), association was markedly pronounced because of the very dominant role played by intermolecular hydrogen bonding.

Uv and visible absorption spectroscopic investigations in relation to macromolecular characteristics of humic substances

The objective of this study is to establish that subjective evaluation of fatty as well as normal ultrasound human liver images based on echotexture (spatial pattern of echoes) and echogenicity by visual inspection can be corroborated by Haralick's statistical texture analysis. Seventy-six ultrasound scan images of human normal livers and twenty-four ultrasound images of fatty livers as identified by the radiologist on the basis of echotexture and echogenecity, have been collected from hospital for this study. An unsupervised neural network learning technique, namely, Self Organising Map (SOM) has been employed to generate profile plots. Using Student's t like statistic for each feature as a measure of distinction between normal and fatty livers, two most appropriate features, namely, maximum probability (Maxp) and uniformity (Uni) are selected from this profile plots. These two features are found to form clusters with little overlap for normal and fatty livers. Thus statistical texture analysis of the ultrasound human images using 'Maxp" and "Uni" presented the best results for corroborating the classification as made the radiologist by visual inspection. This work may be a humble beginning to model the radiologists' perceptual findings that may emerge in future as a new tool with respect to 'ultrasonic biopsy'.

Corroborating the Subjective Classification of Ultrasound Images of Normal and Fatty Human Livers by the Radiologist through Texture Analysis and SOM

The polyelectrolyte character of four natural and ten synthetic hymatomelanic acids, synthesized from possible monomers both in the presence and absence of catalysts, was established by means of viscosity measurements. Intrinsic viscosities were evaluated for the purpose of comparison. The number-average molecular weights of some typical natural and synthetic hymatomelanic acids were determined from osmotic pressure measurements. Using the Flory-Fox relationship in an approximate manner, the root-mean-square average end-to-end separations were also evaluated.

Hymatomelanic acids as polyelectrolytes. I. Viscometric and osmometric studies

By utilizing a static method, based on slight modification of the Wilhelmy plate method, the interfacial properties of one natural and two synthetic hymatomelanic acids were studied at both the air–water and oil–water interfaces. On this basis their number-average molecular weights, flexibility and shape of the macromolecular chains at the interface, and the related thermodynamic parameters were evaluated.

S. K. Mukherjee

Papers

Corroborating the Subjective Classification of Ultrasound Images of Normal and Fatty Human Livers by the Radiologist through Texture Analysis and SOM

Hymatomelanic acids as polyelectrolytes. I. Viscometric and osmometric studies

Studies on adsorption of natural and synthetic hymatomelanic acids at air–water and at oil–water interfaces