The chief interest of Antioch under the empire lies in its relation to Christianity.
In 638, during the reign of the emperor Heraclius, Antioch was conquered by the Muslim Arabs during the Battle of Iron Bridge, and became known in Arabic as أنطاكيّة Antākiyyah.
In recent years, what remains of the Roman and late antique city have suffered severe damage as a result of construction related to the expansion of Antakya. In the 1960s, the last surviving Roman bridge was demolished to make way for a modern two-lane bridge. The northern edge of Antakya has been growing rapidly over recent years, and this construction has begun to expose large portions of the ancient city, which are frequently bulldozed and rarely protected by the local museum.
Board
Board could mean:
Pitman arm
The Pitman arm is a part used in automobiles, trucks, SUVs and other vehicles to steer the wheels. When the steering wheel is turned right or left the pitman transmits the motion it receives from the steering gearbox to the tie rod. A "drop pitman arm" is used to correct the steering when a vehicle has a suspension lift.
F1
F1 is a function key on the keyboard. It is mainly used to open help pages about an application or a part of it.
Solvent
A solvent is a substance that becomes a solution by dissolving a solid, liquid, or gaseous solute. A solvent is usually a liquid, but can also be a solid or gas. The most common solvent in everyday life is water.
Most other commonly-used solvents are organic (carbon-containing) chemicals. These are called organic solvents. Solvents usually have a low boiling point and evaporate easily or can be removed by distillation, thereby leaving the dissolved substance behind. Solvents should therefore not react chemically with the dissolved compounds - they have to be inert. Solvents can also be used to extract soluble compounds from a mixture, the most common example is the brewing of coffee or tea with hot water. Solvents are usually clear and colorless liquids and many have a characteristic smell. The concentration of a solution is the amount of compound that is dissolved in a certain volume of solvent. The solubility is the maximal amount of compound that is soluble in a certain volume of solvent at a specified temperature.
Common uses for organic solvents are in dry cleaning (e.g. tetrachloroethylene), as paint thinners (e.g. toluene, turpentine), as nail polish removers and glue solvents (acetone, methyl acetate, ethyl acetate), in spot removers (e.g. hexane, petrol ether), in detergents (citrus terpenes), in perfumes (ethanol), and in chemical syntheses. Inorganic solvents are used in research chemistry and in a few technological processes.
Some solvents including chloroform and benzene (an ingredient of gasoline) are carcinogenic. Many others can damage internal organs like the liver, the kidneys, or the brain. Many also can catch fire easily. Ways to work safely include:
The solvents are grouped into non-polar, polar aprotic, and polar protic solvents and ordered by increasing polarity. The polarity is given as the Dielectric constant. The density of nonpolar solvents that are heavier than water is bolded.
Chemically inert
In chemistry, the term inert is used to describe something that is not chemically active. The noble gases were described as being inert because they did not react with the other elements or themselves.
Inert gases are completely inert to basic chemical reactions (such as combustion, for example) because their outer valence shell is completely filled with electrons. With a filled outer valence shell, an inert atom is not able to acquire or lose an electron, and is therefore not able to participate in any chemical reactions. For inert atoms or molecules, a lot of energy is involved before it can combine with other elements to form compounds. A high temperature and pressure is necessary, and sometimes requires the presence of a catalyst.
For example, elemental nitrogen is inert under standard room conditions and exists as a diatomic molecule, N. The inertness of nitrogen is due to the presence of the very strong triple covalent bond in the N molecule.
Inert atmospheres of gases such as dinitrogen and argon are routinely used in chemical reactions where air sensitive and water sensitive compounds are handled.
Electron shell
An electron shell, or main energy level, is the part of an atom where electrons are found orbiting the atom's nucleus.
In chemistry and atomic physics, an electron shell may be thought of as an orbit followed by electrons around an atom's nucleus. All atoms have one or more electron shell(s), all of which have varying numbers of electrons.
Each electron shell has one or more electron sub-shells, or sub-levels. Electron shells make up the electron configuration of an atom. The number of electrons that can be in a certain shell is equal to formula_1.
The name for electron shells came from the Bohr model, which states that electrons orbit the nucleus at certain distances so that their orbits form "shells". This term was presented by Niels Henrik David Bohr.
The valence shell is the outermost shell of an atom in its neutral state. The valence shell contains the electrons most likely to be involved in reactions.
In a noble gas, an atom tends to have eight electrons in its outer shell (except helium, which is only able to fill its shell with two electrons). Noble gases serve as the model for the octet rule, which states that atoms tend to form bonds or create ions so that they can have eight electrons in their outermost shell. This is mostly applicable to the main-group elements of the second and third periods.
For coordination complexes containing transition metals, the valence shell consists of 18 electrons. This is referred to as the "eighteen electron rule".
Electron sub-shells are identified by the letters s, p, d, f, g, h, i, etc., corresponding to the : 0, 1, 2, 3, 4, 5, 6, etc. Each shell is able to hold 2, 6, 10, 14, and 18 electrons respectively.
Wheelchair
A wheelchair is a type of chair usually used by disabled people.
A wheelchair is moved either manually (by pushing the wheels with the hands, or pushed from behind with handles by somebody who is not sitting in the wheelchair) or by automated systems such as electric motors which can be controlled by the wheelchair user (the person sitting in the chair) or by somebody walking behind or beside the wheelchair if the wheelchair user needs help to move their wheelchair.
Wheelchairs are used by people for whom walking is difficult or impossible due to illness, injury, or disability. Wheelchairs can have extra cushions and other parts added to improve support if the wheelchair user cannot keep their body in a good sitting position, or to make the wheelchair more comfortable to sit in. The earliest record of the wheelchair in England dates from the 1670s [Oxford English Dictionary, (2nd Ed.), 1989, Vol. XX., p. 203.], and in continental Europe this technology dates back to the German Renaissance.
Fuel oil
Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue at the oil refinery.
Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash point of approximately +40 °C and oils burned in cotton or wool-wick burners. In this sense, diesel is a type of fuel oil. Fuel oil is made of long hydrocarbon chains, particularly alkanes, cycloalkanes and aromatics. The term "fuel oil" is also used in a stricter sense to refer only to the heaviest commercial fuel that can be obtained from crude oil, heavier than gasoline and naphtha.