What is defined as a semi-permeable membrane in this context?

In the context of this question, a semi-permeable membrane is best defined as a synthetic barrier. Semi-permeable membranes are materials that allow certain molecules or ions to pass through while blocking others. They are commonly used in various fields, including biological and chemical systems, to control the movement of substances across a boundary.

In many applications, a semi-permeable membrane can be created through synthetic materials designed to selectively allow the passage of specific particles based on size, charge, or solubility, acting as a barrier that regulates what can move through. Understanding the properties and functions of such membranes is crucial in areas like gas turbine systems, where separation and filtration of substances may be required.

The idea of a living organism inside does not align with the definition of a semi-permeable membrane, as living organisms are complex systems that have their own membranes but are not classified as membranes themselves.