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Minerals, Volume 2, Issue 2 (June 2012), Pages 85-168

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Research

Open AccessArticle Biochemical Change at the Setting-up of the Crossed-Lamellar Layer in Nerita undata Shell (Mollusca, Gastropoda)
Minerals 2012, 2(2), 85-99; doi:10.3390/min2020085
Received: 28 January 2012 / Revised: 24 February 2012 / Accepted: 21 March 2012 / Published: 29 March 2012
Cited by 3 | PDF Full-text (2006 KB) | HTML Full-text | XML Full-text
Abstract
Nerita undata is a marine gastropod, the shell of which consists of an external layer composed of very fine, long and undulating calcite prisms, and of an internal aragonite crossed-lamellar layer. As for any Ca-carbonate shell, both layers are composite materials, resulting from
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Nerita undata is a marine gastropod, the shell of which consists of an external layer composed of very fine, long and undulating calcite prisms, and of an internal aragonite crossed-lamellar layer. As for any Ca-carbonate shell, both layers are composite materials, resulting from the sub-micrometric association of organic macromolecules with the mineral phase. But at the transition between the two layers, in situ synchrotron-based mapping using μ-XANES spectroscopy performed at the S K-edge and SR-FTIR spectroscopy reveals that biochemical compositions change correlatively with the mineral phase, such as displayed by the distribution of sulfur-containing organic compounds (S-polysaccharides or S-amino acids) and organic molecular groups (amide I and II bands). These results highlight the complex change of secretory activity operated by the mineralizing tissue (the mollusk mantle) between these two parts of the shell, which is suspected to minutely control the setting-up of the crossed-lamellar microstructural pattern over the calcite prisms—A not so straightforward feature. Full article
(This article belongs to the Special Issue Advances in Biominerals)
Open AccessArticle Dehydration and Rehydration of Carbonated Fluor- and Hydroxylapatite
Minerals 2012, 2(2), 100-117; doi:10.3390/min2020100
Received: 12 January 2012 / Revised: 19 March 2012 / Accepted: 21 March 2012 / Published: 30 March 2012
Cited by 7 | PDF Full-text (615 KB) | HTML Full-text | XML Full-text
Abstract
The recent definitive deuterium solid state NMR spectroscopic evidence for structural water in fluor- and hydroxylapatites has prompted our study of the conditions necessary for the removal and reincorporation of this important structural feature of apatites. Thermal gravimetric analysis of 20 synthetic carbonated
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The recent definitive deuterium solid state NMR spectroscopic evidence for structural water in fluor- and hydroxylapatites has prompted our study of the conditions necessary for the removal and reincorporation of this important structural feature of apatites. Thermal gravimetric analysis of 20 synthetic carbonated calcium hydroxylapatite (CCaApOH) samples and nine carbonated calcium fluorapatite (CCaApF) samples has been used to determine the amount of structural and adsorbed water in each sample. No correlation between the weight percent and number of moles of structural water and the weight percent carbonate in CCaApOH and CCaApF has been found. In contrast, there appears to be a relationship between the amount of adsorbed water and the carbonate concentration in the fluorapatites prepared with a two hour digestion time, as well as in the hydroxylapatites prepared with one hour digestion periods, presumably due to the effect of carbonate on crystallite size. Structural water can be removed from the apatite lattice, primarily above 200 °C, but heating to over 550 °C is required for complete removal. This water can be partly reincorporated through an apparently kinetically-controlled process that is enhanced by an increase in time and/or temperature. We speculate that the incorporation of structural water occurs at the beginning of the formation of the apatite structure, approximately coincident with the incorporation of carbonate. We also speculate that water is both removed and reincorporated by proton transfers from water molecules to hydroxide ions. Full article
Figures

Open AccessArticle A Novel Method for Culturing of Leptothrix sp. Strain OUMS1 in Natural Conditions
Minerals 2012, 2(2), 118-128; doi:10.3390/min2020118
Received: 8 February 2012 / Revised: 23 March 2012 / Accepted: 15 May 2012 / Published: 23 May 2012
Cited by 6 | PDF Full-text (419 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Although some strains of Leptothrix spp. isolated from aquatic environments have been characterized by culturing them in laboratory conditions, they often show morphological and chemical features distinct from those found in natural environments. To resolve this discrepancy, a novel cultivation method was devised
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Although some strains of Leptothrix spp. isolated from aquatic environments have been characterized by culturing them in laboratory conditions, they often show morphological and chemical features distinct from those found in natural environments. To resolve this discrepancy, a novel cultivation method was devised for culturing such strains in natural groundwater. Leptothrix sp. strain OUMS1 was pre-cultured in a medium lacking Fe for 2 days, and then injected into a small dialysis tube bag and immersed in a container with continuously flowing groundwater for 1–3 and 14 days. Microscopic analysis of the initial phase of sheath formation and arbitrary comparisons with medium cultures revealed that in groundwater the surface coat of the sheath comprised much thinner fibrils, and an inner sheath wall that was much thinner and more indistinct compared with medium cultures. These differences were probably attributable to poorer secretion from the cell surface in groundwater conditions. A nutrient-rich medium likely activates cell metabolism and promotes secretion, resulting in a thicker inner sheath wall and thicker outer coat fibrils. Aqueous-phase Fe was deposited on immature sheaths in a similar manner in both cultures. These results indicate that laboratory culture of isolated microbes does not always reflect their characteristics in natural environments. Full article
(This article belongs to the Special Issue Advances in Biominerals)
Open AccessArticle Psycho-Social Issues in Mine Emergencies: The Impact on the Individual, the Organization and the Community
Minerals 2012, 2(2), 129-168; doi:10.3390/min2020129
Received: 12 April 2012 / Revised: 15 May 2012 / Accepted: 17 May 2012 / Published: 11 June 2012
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Abstract
This paper draws on research conducted in the past two decades examining issues related to the human element in mine disasters. While much of the emergency response community employs a systems approach that takes into account psychosocial issues as they impact all aspects
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This paper draws on research conducted in the past two decades examining issues related to the human element in mine disasters. While much of the emergency response community employs a systems approach that takes into account psychosocial issues as they impact all aspects of an emergency, the mining industry has lagged behind in integrating this critical element. It is only within the past few years that behavioral interventions have begun to be seen as a part of disaster readiness and resiliency in the industry. The authors discuss the potential applications of psychosocial studies and suggest ways to improve mine emergency planning, psychological support, and decision-making during a response, as well as actions in the aftermath of incidents. Topics covered, among others, include an economic rationale for including such studies in planning a mine emergency response, sociological issues as they impact such things as leadership and rescue team dynamics, and psychological issues that have an effect on individual capacity to function under stress such as during escape, in refuge alternatives, and in body recovery. This information is intended to influence the mine emergency escape curriculum and impact actions and decision-making during and after a mine emergency. The ultimate goal is to mitigate the trauma experienced by individuals, the organization, and the community. Full article
(This article belongs to the Special Issue Safety & Health in Mining)

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