Neck masses are common in adults, but the underlying cause is not always easily identified. This guideline is an important instrument for the early diagnosis and treatment of potentially malignant growths, especially with the rise of HPV-related head and neck cancer.
It is easily produced by igniting a mixture of zinc and sulfur. Since zinc sulfide is insoluble in water, it can also be produced in a precipitation reaction. Solutions containing Zn 2+ salts readily form a precipitate ZnS in the presence of sulfide ions (e.g., from H 2 S). Zn 2+ + S 2â â ZnS. This reaction is the basis of a gravimetric analysis for zinc.
The main problems with the higher zinc alloys are dezincification and stress corrosion cracking (SCC). In dezincification, a porous layer of zinc free material is formed locally or in layers on the surface. Dezincification in the high-zinc alloys can occur in a wide variety of acid, neutral and alkaline media. Dezincification can be avoided by maintaining the zinc content below about 15%, and minimized by adding 1% tin such as in Admiralty brass (C44300) and Naval brass (C46400).