High blood potassium
Calcium gluconate is used as a cardioprotective agent in people with high blood potassium levels, with one alternative being the use of calcium chloride. It is recommended when the potassium levels are high (>6.5 mmol/L) or when the electrocardiogram (ECG) shows changes due to high blood potassium.Though it does not have an effect on potassium levels in the blood, it reduces the excitability of cardiomyocytes, thereby lowering the likelihood of cardiac arrhythmias. Magnesium sulfate overdose
It is also used to counteract an overdose of Epsom salts magnesium sulfate, which is often administered to pregnant women in order to prophylactically prevent seizures (as in a patient experiencing preeclampsia). Magnesium sulfate is no longer given to pregnant women who are experiencing premature labor in order to slow or stop their contractions (other tocolytics are now used instead due to better efficacy and side effect profiles). Excess magnesium sulfate results in magnesium sulfate toxicity, which results in both respiratory depression and a loss of deep tendon reflexes (hyporeflexia). Hydrofluoric acid burns
Gel preparations of calcium gluconate are used to treat hydrofluoric acid burns. The calcium gluconate reacts with hydrofluoric acid to form insoluble, non-toxic calcium fluoride. In addition to a 2.5% calcium gluconate gel being applied directly to the chemical burn, the person may also receive calcium gluconate supplements because the fluoride ion precipitates serum calcium, causing hypocalcemia. Cardiac arrest
While intravenous calcium has been used in cardiac arrest, its general use is not recommended.
This is ascribed to electron exchange between the FeII and FeIII centres in Fe3O4. Uses
Fe3O4 is used as a black pigment and is known as C.I pigment black 11 (C.I. No.77499) or Mars Black.Fe3O4 is used as a catalyst in the Haber process and in the water-gas shift reaction. The latter uses an HTS (high temperature shift catalyst) of iron oxide stabilised by chromium oxide. This iron–chrome catalyst is reduced at reactor start up to generate Fe3O4 from α-Fe2O3  and Cr2O3 to CrO3.Bluing is a passivation process that produces a layer of Fe3O4 on the surface of steel to protect it from rust. Along with sulfur and aluminium, it is an ingredient in steel-cutting thermite. Medical uses
Nano particles of Fe3O4 are used as contrast agents in MRI scanning.Ferumoxytol, sold under the brand names Feraheme and Rienso, is an intravenous Fe3O4 preparation for treatment of anemia resulting from chronic kidney disease. Ferumoxytol is manufactured and globally distributed by AMAG Pharmaceuticals. Biological occurrence
Magnetite has been found as nano-crystals in magnetotactic bacteria (42–45 nm) and in the beak tissue of homing pigeons. References
External links
"Ferumoxytol". Drug Information Portal. U.S. National Library of Medicine.