Soldering other precipitation may wash the lead into the groundwater. Unfortunately, most lead-free solders are not eutectic formulations, melting at around , making it more difficult to create reliable joints with them. Other common solders include low-temperature formulations (often containing bismuth), which are often used to join previously-soldered assemblies without unsoldering earlier connections, and high-temperature formulations (usually containing silver) which are used for high-temperature operation or for first assembly of items which must not become unsoldered during subsequent operations. Alloying silver with other metals changes the melting point, adhesion and wetting characteristics, and tensile strength. Of all the brazing alloys, silver
C-rich stability element been mapped to a pyrimidine-rich segment of its 3' UTR. This region confers stability by directing the assembly of a specific alpha ribonucleoprotein complex at this site. Subsequently Holcik and Liebhaber identified three other highly stable eukaryotic mRNAs that assemble the alpha globin protein complex at homologous pyrimidine-rich regions within their 3'UTRs (rabbit lipoxygenase, rat tyrosine hydroxylase, and human alpha(I)-collagen). There is some debate as to the number and identity of trans-acting factors recruited to the C-rich element. However the alpha globin poly(C)-binding protein (alphaCP) is agreed to be the core constituent of what is known as the alpha complex.