Non-stoichiometry and electrochemical properties of lithiated iron hydroxysulfides.

LiFeOHS is a material with Li2(OH)2 layers intercalated between Fe2S2 planes. Its hydrothermal synthesis in various concentrations of LiOH yields materials with a high non-stoichiometry of the Li/Fe ratio which can be explained by partial substitution of Li+ for Fe2+ in the Li2(OH)2 layers. Thermogravimetry, X-ray diffraction and Mössbauer studies indicate that the charge balance is obtained by substitution of hydroxyl ions OH- by oxide ions O2-. This material has been tested as an electrode for lithium-ion batteries against lithium metal. Specific capacities above 200 mA h g-1 at C/10 are achieved, involving 1 lithium per chemical formula when cycled between 1 V and 3 V vs. lithium. The first irreversible discharge leads to the insertion of one lithium atom and the evolution of hydrogen gas while iron remains in its +2-oxidation state. An original Li2OFeS oxysulfide is formed. The following reversible oxidation/reduction cycles involve the Fe3+/Fe2+ redox couple between the two limiting compositions: Li2OFeIIS and LiOFeIIIS.

Comparative structural and vibrational investigations between cocoa butter (CB) and cocoa butter equivalent (CBE) by ESI/MALDI-HRMS, XRD, DSC, MIR and Raman spectroscopy.

A high quality chocolate requires not only a shiny surface, a crunchy and pleasant texture, but also a proper resistance to blooming. All these characteristics are influenced by the physical and chemical properties of the components, which are directly related to their crystalline structure. Some works found that the proportion of cocoa butter (CB), cocoa butter equivalent (CBE) and milk fatty acid (AMF) tend to strongly delay the blooming when mixing them. The goal of our research is to determine how the choice of adding CBE to the mixture delays chocolate blooming. ESI/MALDI-HRMS, X-ray, DSC, MIR and Raman investigations were used to analyze the structure features and the vibrational modes of CB and CBE. The comparison of these experimental results between CB and CBE made it possible to highlight markers of differentiation between CB and CBE which seems to explain the impact of CBE in the chocolate blooming. Part of these triglycerides remains in form IV instead. The presence of the latter seems to be a key parameter that favors the transformation deceleration to the form VI, which is responsible for the fat bloom development.

Temperature dependent Raman and X-ray diffraction studies of anhydrous milk fat.

Raman spectroscopy was used to characterize the polymorphs and liquid state of anhydrous milk fat, with emphasis placed on the thermal evolution of the ester carbonyl stretching modes (1800-1700cm-1) and the comparative study of the Raman-active CC (1660cm-1) and CH (3000-2700cm-1) vibrational modes. Specific Raman signatures in the crystalline phase were found and attributed to the coexistence of two groups of triglycerides. This was confirmed using differential scanning calorimetry and X-ray diffraction methods. In the ester carbonyl band, the effect of changing temperature on both the number of modes and new defined intensity ratios was studied and enabled polymorph discrimination. CH stretching signals increased with polymorph stability, indicating the dominance of antisymmetric CH methylene vibrations as the anhydrous milk fats crystal lattice became more ordered. The change in intensity of the CH stretching bands as a function of temperature was used to probe the order-disorder transition.

A new sensitive organic/inorganic hybrid material based on titanium oxide for the potentiometric detection of iron(III).

The formation of a new hybrid material based on titanium dioxide as inorganic support and containing an iron organochelator (ICL670) is described. An organophosphorous coupling agent was used to graft the organic molecule on the oxide surface. The attachment of the organic substrate was well-confirmed by FTIR (DRIFT), solid-state (31)P and (13)C CPMAS NMR, thermal analysis and the integrity of the structural and morphological parameters were verified using XRD and TEM analyses. The interaction between the material and dissolved iron(III) was also investigated through potentiometric measurements and demonstrated the interest of this new non-siliceous based hybrid material. The obtained linear evolution of the open circuit potential from 10(-2) to 10(-6) mol L(-1) can be used for the analytical detection of iron(III).

The genesis and collapse of third millennium north mesopotamian civilization.

Archaeological and soil-stratigraphic data define the origin, growth, and collapse of Subir, the third millennium rain-fed agriculture civilization of northern Mesopotamia on the Habur Plains of Syria. At 2200 B. C., a marked increase in aridity and wind circulation, subsequent to a volcanic eruption, induced a considerable degradation of land-use conditions. After four centuries of urban life, this abrupt climatic change evidently caused abandonment of Tell Leilan, regional desertion, and collapse of the Akkadian empire based in southern Mesopotamia. Synchronous collapse in adjacent regions suggests that the impact of the abrupt climatic change was extensive.