These ions, like the hydrogen ions that are the heart of every acid, have a single positive charge.

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When they are done working, the particles reunite with the hydrogen ions and with oxygen in the air to emit water.

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Instead of oxygen ions, Dr Bruel fires hydrogen ions into the silicon.

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This liberates hydrogen ions for the acidity, turns insoluble sulfide into very soluble sulfate, and creates rust from reduced iron, a fascinating, if annoying, chemical process.

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So by building up the concentration of ammonium ions inside its retaining membrane, H. pylori is able to fend off the destructive attentions of the hydrogen ions in stomach acid and thus live free from competition by less hardy germs.

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Meanwhile, the hydrogen's stripped-off electrons race around the outside, trying to rejoin their ions, generating current in the process.

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