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Quantitative inorganic analysis
01 Jan 1957-
About: The article was published on 1957-01-01 and is currently open access. It has received 1391 citations till now.
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TL;DR: It is suggested that carboxyl groups provide the major site of metal deposition in the B. subtilis wall, whereas extraction of teichoic acid caused a stoichiometric reduction in levels.
Abstract: Amine and carboxyl groups of the cell wall of Bacillus subtilis were chemically modified individually to neutralize their electrochemical charge for determination of their contribution to the metal uptake process. Mild alkali treatment removed ca. 94% of the constituent teichoic acid (expressed as inorganic phosphorus) and allowed estimation of metal interaction with phosphodiester bonds. Chemical modifications of amine functions did not reduce the metal uptake values as compared to native walls, whereas extraction of teichoic acid caused a stoichiometric reduction in levels. In contrast, alteration of carboxyl groups severely limited metal deposition of most of the metals tested. X-ray diffraction and electron microscopy suggested, in this case, that the form and structure of the metal deposit could be different from that found in native walls. The observations suggest that carboxyl groups provide the major site of metal deposition in the B. subtilis wall.
984 citations
01 Mar 1974
TL;DR: An experimental investigation has shown that H+ and OH− are potential determining ions for the δMnO2 surface The pH (ZPC) was determined using electrophoretic mobilities and Na+ and K+ adsorption and found to be 225 Alkalimetric titration curves failed to provide a direct determination of the pH as mentioned in this paper.
Abstract: An experimental investigation has shown that H+ and OH− are potential determining ions for the δMnO2 surface The pH (ZPC) was determined using electrophoretic mobilities and Na+ and K+ adsorption and found to be 225 Alkalimetric titration curves failed to provide a direct determination of the pH (ZPC), however, when combined with the Na+ adsorption data they provide a means for estimating the surface charge Surface charge values of approximately 100 μ C/cm2 were found at pH 8, considerably higher than the charge on SiO2 which has a similar pH (ZPC) Below pH 35 manganese was released to solution and the experimental data suggest that this is due to the reduction of MnO2 δMnO2 is thermodynamically unstable with respect to H2O below that pH
473 citations
TL;DR: The distributions of the concentrations of methane, ethene, ethane, propene, and propane in twelve l-to 2m-long gravity cores for two transects from nearshore to midslope off the southwest Texas Gulf Coast are reported in this article.
Abstract: The distributions of the concentrations of methane, ethene, ethane, propene, and propane in twelve l-to 2-m-long gravity cores for two transects from nearshore to midslope off the southwest Texas Gulf Coast are reported. Methane profiles exhibit maxima in the top 40 cm of sediment on the shelf, in contrast to downward increasing gradients in the slope region. Nearshore surface methane concentrations ranging from 50 to 400 tl (normal temperature and pressure) per liter pore water are apparently due to microbial production ijsulfate-free microenvironments such as fecal pellets in a near-seawater sulfate environment. A decrease in sediment methane levels to less than 5 tl/l pore water in downslope sediments is attributed to reduced microbial activity due to lower organic contents and temperatures. Profiles of the saturated and unsaturated C: and Ca hydrocarbons suggest that these gases are also microbia!ly produced. plastic liner, was removed from the core barrel and sectioned at specific depths. Five-centimeter sections were immediately extruded into 0.5-1 containers holding 125 ml of sodium-azide- poisoned hydrocarbon-free seawater. The containers were capped, and the headspaces flushed with helium or nitrogen through septa in the lids. The hydrocarbon gases dissolved in the interstitial water were equilibrated with the gas phase by agitation for 5 min with a high-speed shaker. The shaker also dispersed the sodium azide throughout the sediment to inhibit microbial activity. The headspace gases were then analyzed, or the containers were inverted to form liquid seals around the lids and stored in darkness at near-freezing temperatures until analysis.
447 citations
TL;DR: In this article, a solid phase catalyst for the reduction of 4-nitrophenol in the presence of sodium borohydride has been presented, where the electrostatic field force has been taken into consideration for the immobilization of precursor ions onto the resin beads.
Abstract: Silver nanoshell-coated cationic polystyrene beads have been synthesized at room temperature through immobilization of specific silver precursor ions, followed by wet chemical reduction. The electrostatic field force has been taken into consideration for the immobilization of precursor ions onto the resin beads. The as-synthesized particles were characterized by XRD, XPS, SEM, TEM, EDX, and FTIR studies and have been exploited as a solid phase catalyst for the reduction of 4-nitrophenol in the presence of sodium borohydride. The detailed kinetics of the reduction process was monitored under varied experimental conditions. At the end of the reaction, the catalyst particles remain active. They can thus be separated from the product, 4-aminophenol, and can be recycled a number of times after the quantitative reduction of 4-nitrophenol. The activity of the solid catalyst particles has also been examined to promote the reduction of other nitrophenols, e.g., 2-, 3-nitrophenol. The synthesis of the solid catalyst particles, their applications and detailed kinetic aspects of the reduction of 4-nitrophenol have been reported.
275 citations
TL;DR: In this paper, four leafy vegetables species: Vernonia amygdalina (Bitter leaf), Solanum africana, Amaranthus hybridus (Green tete) and Telfaria occidentalis (Fluted pumpkins) were subjected to proximate analysis and determination of energy values and nutritionally valuable minerals.
231 citations