seleniumrelated

Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal with semiconductor properties and occurs in several allotropes, including gray, red, and black forms. Selenium lies in the chalcogen group of the periodic table and can adopt oxidation states from −2 to +6. It was discovered in 1817 by J. J. Berzelius and has long been used in photography, electronics, and glassmaking.

In industry, selenium is obtained as a byproduct of copper and other metal refining, and is extracted from sulfide-containing ore concentrates. It is used to color glass and ceramics, in pigments, as a trace additive in plastics and rubber, and in electronic and photovoltaic devices. Selenium compounds, such as selenides and selenites, have specialized roles in catalysis and chemical synthesis.

Biologically, selenium is an essential micronutrient for many organisms, including humans, where it is incorporated as the amino acid selenocysteine into selenoproteins such as glutathione peroxidases, thioredoxin reductases, and iodothyronine deiodinases. These enzymes support antioxidant defense and thyroid hormone metabolism. Deficiency can contribute to cardiomyopathy and thyroid disorders, while excessive intake can cause selenium toxicity (selenosis) with symptoms such as hair loss, nail brittleness, and nervous-system effects.

From an environmental and safety perspective, selenium can be toxic at elevated concentrations and may accumulate in water and sediments near mining operations. Regulations limit occupational exposure and environmental releases, and proper handling of selenium compounds is required. Cleanup and remediation strategies address selenium mobility and bioavailability to protect ecosystems and public health.

Beyond chemistry, selenium-related also refers to the Selenium project, an open-source suite of tools for automating web browsers. Selenium WebDriver, Selenium IDE, and Selenium Grid enable web testing across languages such as Java, Python, C#, and JavaScript. The term is commonly used in software development to describe topics connected to this framework.