In chemistry, a superbase is an extremely strong base. It is a compound that has a high affinity for protons.
Hydroxide ion is the strongest base possible in water (aqueous) solutions, but superbases are much stronger than aqueous bases. Such bases are useful in organic synthesis and are fundamental to physical organic chemistry.
Superbases have been described and used since the 1850s. Reactions involving superbases often require special techniques since they are destroyed by water, carbon dioxide, and oxygen in the air. Inert atmosphere techniques and low temperatures minimize these side reactions.
IUPAC defines superbases simply as a "compound having a very high basicity, such as lithium diisopropylamide".
Argyria
Argyria is a medical condition caused by the exposure to silver. People with this condition may have a change in skin color to pale or "greyish".
Windows Task Manager
Windows Task Manager is a task manager application. It is part of the Microsoft Windows NT family of operating systems. Windows Task Manager gives detailed information about computer performance and applications that are currently running. It also gives information about processes and CPU usage, commit charge and memory information, network activity and statistics, logged-in users, and system services. The application can be used to set process priorities, processor affinity, forcibly terminating (ending) processes. In Windows XP only, the application can be used to shut down, restart, hibernate or log off from Windows.
Chemical species
A chemical species is one of a group of atoms, molecules, molecular fragments, ions, etc., made to go through to a chemical process or to a measurement. Generally, a chemical species can be defined as an ensemble of chemically identical molecular entities that can explore the same set of molecular energy levels on a defined time scale. Chemists also use chemical species to mean a set of chemically identical atomic or molecular structural units in a solid array.
For example, when molecules of NaCl dissolve in water we don't really have any NaCl as such in the solution. We have Na and Cl ions because NaCl dissociates. We say the species present in solution are Na(aq) and Cl(aq). In this case, the species present in solution are the ions. In other cases, where the molecules don't dissolve in water, we would have molecular species in solution rather than ionic species.
In supramolecular chemistry, chemical species are those supramolecular structures whose interactions and associations are brought about by forming or breaking intermolecular bonds. Studying these actions is the main topic of supramolecular chemistry.
Task manager
A task manager is a computer program that is used to show information about the processes and programs running on a computer. Task managers also show the general status of the computer. They can be used to terminate (end) processes and programs, as well as change the processes priority. An example of a task manager is Windows Task Manager.
Blind spot (vision)
A blind spot is a part of the visual field our brains get no information from. It is the place in the visual field that corresponds to the lack of light-detecting photoreceptor cells where the optic nerve passes through the optic disc of the retina. Since there are no cells to detect light on the optic disc, a part of the field of vision is not perceived. The brain fills in with surrounding detail with information from the other eye, so the blind spot is not normally perceived.
Although all vertebrates have this blind spot, cephalopod eyes, which are superficially similar, do not. In them, the optic nerve approaches the receptors from behind, so it does not create a break in the retina.
The first documented observation of the phenomenon was in the 1660s by Edme Mariotte in France. At the time it was generally thought that the point at which the optic nerve entered the eye should actually be the most sensitive portion of the retina; however, Mariotte's discovery disproved this theory.
As to why the blind spot is normally not seen, there are two theories. One, less favoured, is that it is simply ignored by the brain. The other is that they are 'filled in' by the brain with information from surrounding areas. Perception theorists have generally favoured this second hypothesis. The filling-in works with quite complex and unusual visual patterns, suggesting an active brain process works to mimic patterns surrounding the blind spot.
These natural blind spots are present only in the eyes of vertebrates. Cephalopods have their optic nerves attached to the back of the retina, so they are not a problem. The vertebrate eye is illogical because light must go through and past the nerve fibres before getting to the retina.
This comes about because vertebrate eyes are outgrowths from the brain; they grow outward from the embryological tissue which forms the brain.
Lo Barnechea
Lo Barnechea is a commune and city of Santiago Province. According to the Chilean census in 2002, Lo Barnechea has an area of and 74,749 people live there..
Incubus (1966 movie)
Incubus is an American horror movie. It is black and white. It was released in 1966 and a restored copy of the movie was released in 2001. Leslie Stevens directed the movie and William Shatner starred in it. The actors in the movie did not speak in English. They spoke in Esperanto. The movie was called "Inkubo" in Esperanto. "Incubus" was lost for many years, but an old copy was found in France. The movie was filmed in 18 days in California during 1965. "Incubus" did not become popular and was only distributed in France. Some people believe the movie is cursed because of all of the bad things that happened to the actors and crew. Several of them died by murder or suicide, or had other bad things happen to them, after making the movie.
Supramolecular chemistry
Supramolecular chemistry is area of chemistry that studies the relationship and linking molecules into bigger systems. It focuses on the chemical systems made up of a discrete number of assembled molecular subunits or components. The study of non-covalent interactions is crucial to understanding many biological processes from cell structure to vision that rely on these forces for structure and function. Biological systems are often the inspiration for supramolecular research.
Chondroitin sulfate
Chondroitin sulfate is a sulfated glycosaminoglycan (GAG). It is a chain of alternating sugars (N-acetylgalactosamine and glucuronic acid). It is usually found attached to proteins as part of a proteoglycan. A chondroitin chain can have over 100 individual sugars, each of which can be sulfated in variable positions and quantities. Chondroitin sulfate is an important structural component of cartilage and provides much of its resistance to compression. Along with glucosamine, chondroitin sulfate has become a widely used dietary supplement for treatment of osteoarthritis. It is commonly extracted from shark cartilage.
Chondroitin sulfate was originally isolated well before chemists learned its structure. So, its name changed over time. Early researchers identified different types of the substance with letters.
"Chondroitin sulfate B" is an old name for dermatan sulfate, and it is no longer classified as a form of chondroitin sulfate.
"Chondroitin", without the "sulfate", has been used to describe a type with little or no sulfation. However, this distinction is not used by all.
The name "chondroitin sulfate" sounds like a salt with a sulfate counter-anion. This is not the case. The sulfate is attached to the sugar with a covalent bond. Since the molecule has multiple negative charges at physiological pH, a cation is present in salts of chondroitin sulfate. Commercial preparations of chondroitin sulfate typically are the sodium salt. Barnhill et al. have suggested that all such preparations of chondroitin sulfate be referred to as "sodium chondroitin" regardless of their sulfation status.