Vinyltrimethylsilane-co-N-vinyl-2-pyrrolidone and vinyltrimethoxysilane-co-N-vinyl-2-pyrrolidone copolymersSynthesis and reactivity ratios

Summary Copolymers containing vinyltrimethylsilane and vinyltrimethoxysilane with N-vinyl-2-pyrrolidone at different compositions were synthesized and characterized. The reactivity ratios was estimated by using the classical Fineman-Ross and Kelen Tüdos linear fitting procedures. These parameters were also estimated through a computer program based on nonlinear minimization algorithm, starting from the r₁ and r₂ values obtained by the former procedures. The analysis of the results allow us to interpret the reactivity behaviour of these polymers in terms of the relative reactivity of the substiuents. The effect of the chemical structure of the polymer side group is discussed in terms of the different contributions to the stabilization of the radical intermediates. Received: 18 February 1998/Revised version: 11 March 1998/Accepted: 16 March 1998     

Nocistatin reverses nociceptin inhibition of glutamate release from rat brain slices

We have examined the effects of the recently described heptadecapeptide nocistatin on K+-evoked glutamate release from rat cerebrocortical slices in vitro. In vivo, nocistatin reverses the action of nociceptin. Nocistatin (100 nM, n = 7) did not inhibit K+-evoked glutamate release alone. Nociceptin (100 nM) inhibited glutamate release by 51.7 +/- 8.3% (P < 0.05, n = 6) and this was fully reversed by nocistatin (100 nM). Nocistatin also appears to be an antagonist of nociceptin action in vitro.     

Multivariate Analysis of Multiple Datasets: a Practical Guide for Chemical Ecology

Chemical ecology has strong links with metabolomics, the large-scale study of all metabolites detectable in a biological sample. Consequently, chemical ecologists are often challenged by the statistical analyses of such large datasets. This holds especially true when the purpose is to integrate multiple datasets to obtain a holistic view and a better understanding of a biological system under study. The present article provides a comprehensive resource to analyze such complex datasets using multivariate methods. It starts from the necessary pre-treatment of data including data transformations and distance calculations, to the application of both gold standard and novel multivariate methods for the integration of different omics data. We illustrate the process of analysis along with detailed results interpretations for six issues representative of the different types of biological questions encountered by chemical ecologists. We provide the necessary knowledge and tools with reproducible R codes and chemical-ecological datasets to practice and teach multivariate methods.     

Natural and NH<Subscript>4</Subscript><Superscript>+</Superscript>-enriched zeolitite amendment effects on nitrate leaching from a reclaimed agricultural soil (Ferrara Province,Italy)

In this paper we report an overview of the main outcomes of a 3-years experimental cultivation carried out in an Italian reclaimed agricultural field amended with different types of zeolitites (rock containing > 50% of zeolites), under cereals cultivation (Sorghum vulgare Pers, Zea mays and Triticum durum). The aim of the experiment was to exploit the properties of zeolite-rich volcanic rocks (zeolitites) for reducing the excessively high NO₃^? content in the soil and in waters flowing out the sub-surface drainage system of the field and flushing into the surface water system, reducing concomitantly also chemical fertilization application rates (up to 50%). Zeolitites were tested both in their natural state and in a NH₄⁺-enriched form, obtained through an enrichment process with NH₄⁺-rich zoo-technical effluents (pig slurry). NO₃^? content in soils and in waters discharged through SSDS were periodically monitored during the experimentation and crop yield quantified. Results showed that, for three consecutive cultivation cycles, the overall NO₃^? concentrations in water extracts was reduced by 45% in the zeolitite treated soils, while in SSDS waters the reduction reached the 64%. Notwithstanding the lower N input from chemical fertilizers, crop yield was not negatively affected in the zeolitite amended soils with respect to the control. Zeolitite addition increased thus soil NH₄⁺ retention and probably influenced several pathways of N losses, allowing a better fertilizer use efficiency by plants and a reduction of the overall NO₃^? concentrations in the surface waters.     

The effect of surface roughness on condensing steam

Heal transfer coefficients for steam condensing on the outside of a smooth, and three artificially roughened pipes have been obtained for a condensate film Reynolds Number range of 1,500 to 9,000. Dimensionless local and mean heat transfer coefficient are presented, and in all cases significant increases in tht coefficients for the rough pipes are observed.     

A robust microcomputer routine for the identification of outlying and influential points in radioimmunoassay standard curves

This paper describes a suite of robust logit-log optimization routines for the fitting of a linear relation to laboratory data. The microcomputer routines assign a weighting value to each data point corresponding to the relative importance of that point. This procedure ensures that the routines identify and deal with any outlying data points. The routines are designed to generate the results of both a standard, unweighted least-squares algorithm and a robust, weighted algorithm thus providing the laboratory analyst with invaluable information concerning the data and the fitted relation. The routines are thoroughly tested on "perfect" and perturbed laboratory data.