Shell chemistry

Because Olivella biplicata snails grow in tidal environments, it was hypothesized that their shell chemistry might be influenced by nearshore seawater chemistry, which would include dissolved minerals from local shoreline deposits. If geology varied enough along the California coast, certain regions might be bathed by seawater with a chemically distinct composition that would be incorporated into the shells. 

Harkness RE, Berkas WR, Norbeck SW, Robinson SM (2000) Water Resources Data, North Dakota, Water Year 1999, Vol. 1 Surface Water. USGS Water Resources of North Dakota ND-99-1 Harrison TM, Copeland P, Kidd WSF, Yin A (1992) Raising Tibet. Science 255 1663-1670 Holmes JA, Chivas AR (2002) Ostracod shell chemistry - Overview. In The Ostracoda Applications in Quaternary Research. Holmes JA, Chivas AR (ed) AGU Geophysical Monograph 131 185-204 Hoppe KA (2006) Correlation between the oxygen isotope ratio of North American bison teeth and local waters Implications for paleoclimatic reconstructions. Earth Planet Sci Lett 244 408-417... 

The lower the surface free energy of the shell chemistry, the smaller is the contact angle hysteresis on the closely packed surface arrays. Further the contact angles varied with increasing height roughness. A possible explanation for this behaviour is that the vertical roughness influences the curvature radius of the liquid in trapped air pockets at the solid-liquid interface as was already assumed in the literature for nanostructured metal surfaces and paraffin-coated steel balls. 

In this work, ordered arrays of core-shell particles were used as model surfaces to study the water wetting behaviour of these surfaces. Two factors were varied in the wetting experiments (i) the shell chemistry and hence the solid surface tension of the organic shell, and (ii) the height roughness from sub- xm up to xm roughness values whereas the Wenzel roughness factor was kept constant. 

As we have seen, J -matrices indicate how bonds and electrons are redistributed in a reaction. These electron and bond shifting schemes can be formally generated and classified. For closed-shell chemistry, 38 R-matrices breaking one, two, or three bonds have been found9, l0 These./ -matrices are of different chemical importance some represent mechanistic steps, others comprise powerful synthetic reactions. A... 

Shell chemistry can be precisely controlled to achieve nnstrained (core)shell epitaxy. For example, the zinc-cadminm alloy, ZnCdSc2 was used for the preparation... 

McCorkle D. C., Martin P. A., Lea D. W., and Klinkhammer G. P. (1995) Evidence of a dissolution effect on benthic foraminiferal shell chemistry delta C-13, Cd/Ca, Ba/Ca, and Sr/Ca results from the Ontong Java Plateau. Paleoceano-graphy 10(4), 699-714. 

It is postulated that the role of the HBP in toughening will be to act similarily to a coreshell particle that is, the core of the HBP will act to cavitate and promote shear yielding, and the shell will be able to be tailored to control aggregation and interactivity with the epoxy-resin matrix. Increases in core should promote cavitation, and shell-chemistry functionalization should increase dissolution and reactivity with the epoxy resin. However, unlike with the core-shell particles, the inherently greater number of shell sites and low viscosity of the HBP will enable the toughening to occur without deleterious effects on other properties. 

We determined the shell C and O isotopic composition of the cultured foraminifera, and compared these isotopic values with the water chemistry of the culture chambers, and also with the shell chemistry of field specimens collected from sites on the North Carolina and South Carolina (USA) continental margin. The culmred foraminifera showed substantial offsets from the 8 C of system water dissolved inorganic carbon (—0.5 to —2.5%c, depending on species) and smaller offsets (0 to — 0.5%o) from the predicted 8 0 of calcite in equilibrium with the culture system water at the growth temperature. These offsets reflect at least three factors species-dependent vital effects ontogenetic variations in shell chemistry and the aqueous carbonate chemistry ([COJ] or pH) of the experimental system. 

However, differences between paired foraminiferal shell chemistry records demonstrate that our understanding of these proxies remains incomplete (e.g. Boyle 1992 Rosenthal et al. 1995 Boyle Rosenthal 1996). Field calibration studies have revealed potential artifacts that can complicate proxy interpretations (McCorkle et al. 1990 Mackensen et al. 1993 McCorkle et al. 1995), and staining studies have documented the microhabitats (i.e. epibenthic (at the sediment-water interface) and endobenthic (within the sediments)) occupied by different benthic foraminiferal species (Corliss 1985 Mackensen Douglas 1989 Corliss Emerson 1990). Staining methods have been used both to focus palaeochemical calibration efforts on live (or recently live) specimens, and to use species microhabitat preferences... 

At sea, flocculent surface sediments were siphoned off the tops of Soutar box cores and gently sieved, taking care to keep the sediment material at in-situ temperatures. The >75 p,m fraction was kept in bottom water at in-situ temperatures for the duration of each cruise, and returned to the laboratory in Columbia, SC, where stock foraminiferal cultures were maintained in a 7 °C environmental chamber. Separate sediment samples from the top 0.5 cm of cores collected at each site were incubated on board the ship at in-situ temperature with the vital probe CeUTracker Green (Molecular Probes, Invitrogen Detection Technologies) to label foraminifera that were alive at the time of core collection (Bernhard 2000), and these sediments were then preserved for later foraminiferal identification and shell chemistry analyses on shore. 

Consistent interspecies differences in foraminiferal 8 C and 8 0 values were observed in comparisons of B. aculeata and R. vilardeboana from the same culture chambers. Since the experiments were designed to minimize the possible influence of microhabitats on shell chemistry, these isotopic differences demonstrate the existence of species-specific, non-environmental vital effects on benthic foraminiferal shell chemistry. 

Before isotopic compositions from fossil benthic foraminiferal specimens are used in palaeoenviron-mental reconstructions, it is important to determine whether the shell chemistry of live individuals (i.e. those stained with rose Bengal Bernhard 2000) of a particular species reflect the conditions of the surrounding seawater, i.e. does the foraminifera calcify in isotopic equilibrium with the surrounding environment ... 

Multicenter Chemistry => Integral Chemistry => Closed Shell Chemistry => Restricted Chemistry. 

In closed shell chemistry, the ic-matrices have even entries on the main diagonal. Making the... 

In closed shell chemistry, all the elements of the set CB n) have each diagonal entry even, or zero. Thus, making the... 

Remark. The basis vectors (Vy + Utj) of closed shell chemistry correspond to the elementary heteroaptia and heterolytic reactions R2 and... 

Because R n) and CR(n) have the same rank, they are isomorphic. We exploit this to establish a relation between general and closed shell chemistry ... 

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