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A pH-dependent model for the speciation of divalent Cu, Zn, Cd, and Pb ions in seawater was constructed with available and estimated thermodynamic stability constants and individual ion activity coefficients.This model was used to calculate the degree of interaction bctwccn each of the metal ions and the anions Cl-, Sod'-, HCOX-, CO,'-, and OH-as a function of pH. Interactions between a cation and an anion were assumed to result only in the formation of complexes with coordination numbers of 1 to 4; polynuclcar and mixedligand complexes wcrc not included in the model.The calculations showed the following: All four metals are complexed to a considerable extent in seawater; with the exception of Cd, the distributions of chemical species of the metals vary greatly with changes in pH; Cu interacts primarily with OH-and COs2-, Zn with OH-, Pb with COa2-and Cl-, and Cd with Cl-; complexes with high coordination numbers (i.e. 3 and 4) are not formed to any appreciable extent in seawater.

Bunsen solubility coefficients for hydrogen in distilled water, in NaCl solutions at two concentrations, and in seawater at three salinities were determined with an estimated accuracy of 0.5%. A new data reduction method. utilizing the least-squares technique, was developed to fit the experimental data to an equation established by Weiss. A table of Bunsen solubility coefficients covering the temperature range -2' to 30°C and the salinity range 0-40 parts per thousand was calculated from the fitted equation. Solubility values for distilled water were in agreement with composite values of several workers reported by Linke. Solubility coefficients for NaCl solutions were compared with previous measurements and with solubility coefficients for seawater.Recent measurements of dissolved hydrogen in surface seawater (7, 72) have indicated an apparent excess of this gas with respect to atmospheric concentrations. Proper interpretation of such information requires accurate saturation values for dissolved hydrogen in seawater. This paper reports the measurement of Bunsen solubility coefficients for hydrogen in distilled water, in NaCl solutions at two concentrations, and in seawater at three salinities.Hydrogen solubilities in distilled water have been reported previously by several workers, but there are considerable differences among their results (7, 6, 9. 73).Generally accepted values are those of Linke ( 5 ) who averaged values from several workers. Solubilities in seawater have not been reported previously. Measurements have. however, been made in NaCl solutions by several investigators, most recently by Morrison and Billett (6).Both graphical and numerical methods have been used previously to reduce gas solubility data with respect to temperature and salinity. Douglas (3) used strictly graphical methods to fit his data for argon and nitrogen. Morrison and Billett (6) used a modified form of Van't Hoff's law to describe their data. Recently, Weiss (70) has established a thermodynamically consistent equation describing solubility in terms of temperature and salinity which he fit to solubility data by a stepwise method involving four separate least-squares fits. In the present work a data reduction method was developed to fit the entire set of solubilities in a single step to Weiss' equation by the least-squares technique. ExperimentalResearch grade hydrogen gas (Linde Specialty Gas, 99.9995% purity) was used for all measurements. Seawater was filtered through 0.45-1.rm Millipore filter membranes, poisoned with HgC12 (1 mg/l.), and stored in the dark. The seawater was then boiled or diluted to obtain desired salinities. Salinities were determined with a Beckman Induction Salinometer having an accuracy of f0.003 parts per thousand. Glass distilled water was used for distilled water measurements. The thermometer used in this work was calibrated against NBS standard ihermometers.' To whom correspondence should be addressed Seawater and distilled water were degassed by the vacuum extraction method developed by Douglas (3)...

To estimate the impact of fish farming operated at household level on nutritional status among children 6-59 months of age, a cross-sectional study was conducted in Zomba district, Malawi. Anthropometric measurements of 66 children in each type of household (fish-farming and non-fish-farming households) and structured interviews with their parents were undertaken. A total of 21 background variables were employed and examined using bivariate and multivariate analyses. Overall, a lower prevalence of malnutrition was detected among the children in fish-farming households than those in non-fish-farming households in all the malnutrition indicators, i.e. stunting, underweight and wasting. In particular, a significantly lower prevalence was detected among the children in fish-farming households than those in non-fish-farming households in both severe (P=0.045) and global underweight (P=0.042). 'Higher proportion of income from fish farming to total income', 'more frequent intake of oil and fats other than never/seldom' and 'breastfeeding practice for the appropriate duration' are the protective factors against being underweight. Household fish farming may have indirectly contributed to lower prevalence of underweight through increasing frequency of intake of oil and fats by strengthening households' purchasing power. The study supports 12 months as the threshold for appropriate breastfeeding duration.

Oligosaccharides in therapeutic recombinant antibodies play important roles in regulation of various biological functions. To monitor the glycosylation profiles of antibody pharmaceuticals in the manufacturing process, a highly sensitive and specific method is required. We extended partial-filling techniques using lectins and exoglycosidases in capillary electrophoresis for the characterization of 8-aminopylene-1,3,6-trisulfonic acid labeled N-linked oligosaccharides derived from the therapeutic antibody rituximab. In the lectin-filling method, Galb1–4GlcNAc-specific Erythrina cristagali agglutinin, a1, 6-linked Fuc-specific Aleuria aurantia lectin and Neu5Aca2–3Gal-specific Maackia amurensis lectin were used. The oligosaccharides migrated through the lectin plug during separation; the changes in separation profiles were observed according to the interaction with the lectins. The glycosidase-filling method allowed rapid digestion as suggested by the electropherograms. Partial-filling CE methods can avoid tedious hands-on procedures such as overnight incubation and optimization reaction condition with lectins and exoglycosidases. Combination of these partial-filling capillary electrophoresis methods makes the characterization of oligosaccharide profiles of therapeutic antibodies easier and faster.

A simple and efficient method was developed for fabrication of an anionic sample preconcentrator on a channel of a commercial poly(methyl methacrylate) (PMMA)-made microchip using no photolithography or etching technique. The originality of our preconcentrator is based on simple photochemical copolymerization of monomers using the following procedure: All channels of the PMMA-made microchip were filled with gel solution comprising acrylamide, N,N'-methylene-bisacrylamide, and 2-acrylamide-2-methylpropanesulfonic acid with riboflavin as a photocatalytic initiator. In situ polymerization near the cross of the sample outlet channel was performed by irradiation with an argon ion laser beam, which is also used as the light source for fluorometric detection. The electrokinetic property and electric repulsion between sample components and anionic groups on the polyacrylamide gel layer produce, trap, and concentrate anions within a few minutes at the interface of the cathodic side of the gel layer. This method displays concentration factors as high as 10 (5). The availability of ionic preconcentrator was demonstrated by applying sensitive analysis of oligosaccharides labeled with 8-aminopyrene-1,3,6-trisulfonate and some glycoproteins labeled with fluorescein isothiocyanate under various buffer systems.

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