Copper in biologyCopper is an essential trace element that is vital to the health of all living things (plants, animals and microorganisms). In humans, copper is essential to the proper functioning of organs and metabolic processes. The human body has complex homeostatic mechanisms which attempt to ensure a constant supply of available copper, while eliminating excess copper whenever this occurs. However, like all essential elements and nutrients, too much or too little nutritional ingestion of copper can result in a corresponding condition of copper excess or deficiency in the body, each of which has its own unique set of adverse health effects.
Antimicrobial copper-alloy touch surfacesAntimicrobial copper-alloy touch surfaces can prevent frequently touched surfaces from serving as reservoirs for the spread of pathogenic microbes. This is especially true in healthcare facilities, where harmful viruses, bacteria, and fungi colonize and persist on doorknobs, push plates, railings, tray tables, tap (faucet) handles, IV poles, HVAC systems, and other equipment. These microbes can sometimes survive on surfaces for more than 30 days.
NanoclusterNanoclusters are atomically precise, crystalline materials most often existing on the 0-2 nanometer scale. They are often considered kinetically stable intermediates that form during the synthesis of comparatively larger materials such as semiconductor and metallic nanocrystals. The majority of research conducted to study nanoclusters has focused on characterizing their crystal structures and understanding their role in the nucleation and growth mechanisms of larger materials.
Negative-feedback amplifierA negative-feedback amplifier (or feedback amplifier) is an electronic amplifier that subtracts a fraction of its output from its input, so that negative feedback opposes the original signal. The applied negative feedback can improve its performance (gain stability, linearity, frequency response, step response) and reduces sensitivity to parameter variations due to manufacturing or environment. Because of these advantages, many amplifiers and control systems use negative feedback.
N-Butyllithiumn-Butyllithium C4H9Li (abbreviated n-BuLi) is an organolithium reagent. It is widely used as a polymerization initiator in the production of elastomers such as polybutadiene or styrene-butadiene-styrene (SBS). Also, it is broadly employed as a strong base (superbase) in the synthesis of organic compounds as in the pharmaceutical industry. Butyllithium is commercially available as solutions (15%, 25%, 1.5 M, 2 M, 2.5 M, 10 M, etc.) in alkanes such as pentane, hexanes, and heptanes.
Climate change feedbackClimate change feedbacks are effects of global warming that amplify or diminish the effect of forces that initially cause the warming. Positive feedbacks enhance global warming while negative feedbacks weaken it. Feedbacks are important in the understanding of climate change because they play an important part in determining the sensitivity of the climate to warming forces. Climate forcings and feedbacks together determine how much and how fast the climate changes.
MolybdenumMolybdenum is a chemical element with the symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from Neo-Latin molybdaenum, which is based on Ancient Greek Μόλυβδος molybdos, meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm.
AzuriteAzurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the type locality at Chessy-les-Mines near Lyon, France. The mineral, a basic carbonate with the chemical formula Cu3(CO3)2(OH)2, has been known since ancient times, and was mentioned in Pliny the Elder's Natural History under the Greek name (κυανός: "deep blue," root of English cyan) and the Latin name caeruleum. Copper (Cu2+) gives it its blue color.
ArsenicArsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the grey form, which has a metallic appearance, is important to industry. The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices.
Negative resistanceIn electronics, negative resistance (NR) is a property of some electrical circuits and devices in which an increase in voltage across the device's terminals results in a decrease in electric current through it. This is in contrast to an ordinary resistor in which an increase of applied voltage causes a proportional increase in current due to Ohm's law, resulting in a positive resistance. While a positive resistance consumes power from current passing through it, a negative resistance produces power.
