Magnesium metal is an ideal rechargeable battery anode material because of its high volumetric energy density, high negative reduction potential and natural abundance. Coupling Mg with high capacity, low-cost cathode materials such as electrophilic sulphur is only possible with a non-nucleophilic electrolyte. Here we show how the crystallization of the electrochemically active species formed from the reaction between hexamethyldisilazide magnesium chloride and aluminum trichloride enables the synthesis of a non-nucleophilic electrolyte. Furthermore, crystallization was essential in the identification of the electroactive species, [Mg2(μ-Cl)3·6THF]+, and vital to improvements in the voltage stability and coulombic efficiency of the electrolyte. X-ray photoelectron spectroscopy analysis of the sulphur electrode confirmed that the electrochemical conversion between sulphur and magnesium sulfide can be successfully performed using this electrolyte.

We report a static secondary ion mass spectrometry (SSIMS) study of self-assembled monolayers (SAMs)of alkanethiols [CH3(CH2)nSH, where n = 1,9,11,15,17] adsorbed on Au. A rich variety of molecular secondary ions are observed in the negative SSIMS spectra including (M -H)~, (AuM)~, (AuSM)~, and (Au2[M -H])~a nd a relatively strong (Au[M -H]2)~w here M is the complete alkanethiol molecule. Sulfonates and alkanesulfonates are observed in SSIMS spectra of SAMs that have been atmosphere exposed for prolonged periods; however, sulfonate species are not detected from samples that are analyzed immediately after withdrawal from thiol-ethanol solutions. SSIMS results indicate that sulfonates formed by air oxidation can be displaced by reimmersion of samples in thiol adsorbate solution. Molecular secondary ions are not observed for perfluoromercaptan and carboxylic acid-terminated SAMs, although spectra distinct from those of the alkanethiol SAMs were obtained. Damage profiles indicate that the emission of molecular secondary ions is very sensitive to extremely low primary ion beam doses. In addition, the relative intensities of Au substrate and molecular ions are strongly influenced by the energy of the primary ion beam suggesting a beam penetration depth effect.

Proton pumping across the mitochondrial inner membrane and proton leak back through the natural proton conductance pathway make up a futile cycle that dissipates redox energy. We measured respiration and average mitochondrial membrane potential in perfused rat hindquarter with maximal tetanic contraction of the left gastrocnemius-soleus-plantaris muscle group, and we estimate that the mitochondrial proton cycle accounted for 34% of the respiration rate of the preparation. Similar measurements in rat hepatocytes given substrates to cause a high rate of gluconeogenesis and ureagenesis showed that the proton cycle accounted for 22% of the respiration rate of these cells. Combining these in vitro values with literature values for the contribution of skeletal muscle and liver to standard metabolic rate (SMR), we calculate that the proton cycle in working muscle and liver may account for 15% of SMR in vivo. Although this value is less than the 20% of SMR we calculated previously using data from resting skeletal muscle and hepatocytes, it is still large, and we conclude that the futile proton cycle is a major contributor to SMR.

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