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-element slow environment. Note that the definition of C-element can be easily generalized for multiple-valued logic or even for continuous signals: For example, the truth table for a balanced ternary C-element with two inputs is Depending on the requirements to the switching speed and power consumption, the C-element can be realized as a coarse- or fine-grain circuit. Also, one should distinguish between single-output and differential realizations of C-element. Differential realization is possible using only NANDs (only NORs). A single-output realization is workable if and only if: There is a number of different single-output circuits of C-element built on logic gates. In