Welcome to Helotes. Surrounded by the beauty of the Texas Hill County, the City of Helotes is a vibrant community boasting a flourishing economy and a high quality of life. Located just northwest of San Antonio, Helotes was incorporated in 1981 as a Type A General Law City.
The passive diffusion samplers act as a filter, so field filtering is not necessary. In fact, passive diffusion bags (PDBs) will block potassium permanganate from samples for sites using it in their remediation processes. PDB Samplers. Samples volatile organics. Available in both pre-filled and unfilled versions.
Facilitated Diffusion. Facilitated diffusion involves the use of a protein to transport molecules across the cell membrane. Photo Credit: Mariana Ruiz Villarreal. Facilitated diffusion is a type of passive transport that allows substances to cross membranes with the assistance of special transport proteins.