Portland cementPortland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding 2 to 3 percent of gypsum. Several types of portland cement are available.
User interfaceIn the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine from the human end, while the machine simultaneously feeds back information that aids the operators' decision-making process. Examples of this broad concept of user interfaces include the interactive aspects of computer operating systems, hand tools, heavy machinery operator controls and process controls.
Philosophy of lawPhilosophy of law is a branch of philosophy that examines the nature of law and law's relationship to other systems of norms, especially ethics and political philosophy. It asks questions like "What is law?", "What are the criteria for legal validity?", and "What is the relationship between law and morality?" Philosophy of law and jurisprudence are often used interchangeably, though jurisprudence sometimes encompasses forms of reasoning that fit into economics or sociology.
