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The microstructure and composition, including chemical speciation of sulphur (S), of two mollusc shells were investigated using a combination of scanning electron microscopy, X-ray absorption near-edge structure spectroscopy (XANES) and electron probe microanalysis (EPMA). The shell of Pinna is composed of monocrystalline, and Pinctada, of polycrystalline, calcite prisms separated by organic-rich walls. Sulphur speciation information from XANES spectra using a scanning X-ray microscope showed that the protein S content of the interprismatic walls is higher than the S[O.sup.4] content, whereas the reverse is true for the intraprismatic structures. High-spatial-resolution XANES maps for the different S species across adjacent calcite prisms confirm their distinctive distributions in the molluscan shells and illustrate the presence of narrow, submicron transverse growth features. On a larger scale, a series of wider growth zones, incorporating the submicron zones, are aligned parallel to each other and cross-cut many calcite prisms. EPMA element maps for magnesium (Mg) and S demonstrate that these growth increments are compositionally zoned, comprising alternating layers of high mineral (Mg-rich) and high organic (S-rich) components. Additionally, these maps confirm that the organic interprismatic walls have lower Mg and higher S than the intraprismatic structures.

Abstract Michael addition reactions were utilized to form A[B.sub.2] type monomers and esterified to form polyaspartate esters (PASPE). FTIR and NMR spectroscopic methods indicate that a relatively linear architecture was [...]

Describes the method for screening rice germplasm for resistance to the African rice gall midge (AfRGM) in Nigeria. Role of partial resistance on the management of AfRGM; Development of resistant varieties; Percentage rate of tiller infestation levels.

Farmer-managed trials of the rice variety Cisadane were undertaken at 47 rainfed lowland sites around Abakaliki, south-east Nigeria, a major outbreak area of the African rice gall midge (ARGM). At each site a plot of Cisadane was grown alongside a control plot of the participating farmer's usual variety. On average the Cisadane yielded 26% higher than the controls but ARGM infestation levels on it were only slightly lower, suggesting thatithad greater tolerance to the pest butlittle antixenotic or antibiotic resistance. For all of 14 evaluation criteria, most participating farmers rated Cisadane as better than their control varieties. It appears to be a useful component for an ARGM management strategy. Regression analyses of yield on alternative variables for ARGM infestation derived from data recorded at 3, 7 or 11 w.a.t. (weeks after transplanting) showed that the log-transformed percent tiller infestation at 7 w.a.t. was the best predictor of yield. Variables for site topography, water level, fertilizer use in the nursery, and plant spacing also had significant partial regression coefficients. Excluding plots with tiller infestation levels above 30%, the relationship between yield and infestation was approximately linear and suggested a yield loss of 2.9% per 1% increase in infestation. [ABSTRACT FROM AUTHOR]