Isotope characterization and estimated temperature of formation of calcite veins in ODP Sites 124-768 and 124-770 (Table 1)

Secondary carbonate minerals were recovered within the basalts at both ODP Sites 768 and 770 in the Sulu and Celebes seas. Petrographic and X-ray diffraction analyses indicate that the carbonates are calcites. Other alteration products recognized in the thin sections are smectites, iron oxides, and gypsum. The 13C values of carbonates from both sites range from 1.6 per mil to 2.3 per mil, which are indicative of inorganic carbonate formation with no contributions from 13C-depleted sources such as oxidized organic carbon or methane. The oxygen isotopes at Site 770 range from 30.8 per mil to 31.6 per mil, which indicates a pervasive circulation of cold seawater (9° to 12°C) during alteration of the Celebes Sea basalts. In contrast, carbonates associated with Site 768 basalts have less positive d18O values (21.0 per mil to 27.3 per mil). A lighter 18O isotopic signature indicates the formation of secondary calcite at either higher temperatures or in a system closed to seawater. The rapidly deposited pyroclastic flows at Site 768 would have limited water access to the crust very soon after its formation, which leads us to speculate that the carbonates in the Sulu Sea basalts were formed by isotopically modified fluids resulting from basalt alteration in a closed system.

A note on the effect of the HCl concentration on the heat of solution of thorium tetrachloride /

Work performed at the Argonne National Laboratory.

The total and free energies of formation of the oxides of thirty-two metals,

Bibliographical foot-notes.

The art of hatching and bringing up domestick fowls of all kinds at any time of the year. Either by means of the heat of hot-beds, or that of common fire.

Goldsmiths'-Kress no. 08498.8-1, suppl.

Thermometrical observations as connected with navigation : the utility ... in ascertaining the relative heat of the sea-water ... to discover the passage of a vessel through the Gulf Stream and from deep water into soundings ... to avoid danger ... /

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Identities: Of light and heat, of caloric and electricity ...

Mode of access: Internet.

Comparative studies of hyperhomodesmotic reactions for the calculation of standard heats of formation of fullerenes

How can the accuracy of the calculated standard heats of formation Delta H-f(0) of fullerenes be improved? How reliable are the values of Delta H-f(0) calculated from hyperhomodesmotic reactions? This work is the first to address these questions. By comparing the results obtained from three hyperhomodesmotic reactions containing only fullerenes, it is illustrated that both the resonance contribution and the strain energy contribution should be considered in the construction of hyperhomodesmotic reactions. An attempt to construct such hyperhomodesmotic reactions for fullerenes has been carried out, and several new insights are indicated.

Exploring oxidative modifications of tyrosine:an update on mechanisms of formation, advances in analysis and biological consequences

Protein oxidation is increasingly recognised as an important modulator of biochemical pathways controlling both physiological and pathological processes. While much attention has focused on cysteine modifications in reversible redox signalling, there is increasing evidence that other protein residues are oxidised in vivo with impact on cellular homeostasis and redox signalling pathways. A notable example is tyrosine, which can undergo a number of oxidative post-translational modifications to form 3-hydroxy-tyrosine, tyrosine crosslinks, 3-nitrotyrosine and halogenated tyrosine, with different effects on cellular functions. Tyrosine oxidation has been studied extensively in vitro, and this has generated detailed information about the molecular mechanisms that may occur in vivo. An important aspect of studying tyrosine oxidation both in vitro and in biological systems is the ability to monitor the formation of oxidised derivatives, which depends on a variety of analytical techniques. While antibody-dependent techniques such as ELISAs are commonly used, these have limitations, and more specific assays based on spectroscopic or spectrometric techniques are required to provide information on the exact residues modified and the nature of the modification. These approaches have helped understanding of the consequences of tyrosine oxidation in biological systems, especially its effects on cell signalling and cell dysfunction, linking to roles in disease. There is mounting evidence that tyrosine oxidation processes are important in vivo and can contribute to cellular pathology.