In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms, but differ in the three-dimensional orientations of their atoms in space. This contrasts with structural isomers, which share the same molecular formula, but the bond connections or their order differs. By definition, molecules that are stereoisomers of each other represent the same structural isomer. Enantiomers known as optical isomers, are two stereoisomers that are related to each other by a reflection: they are mirror images of each other that are non-superposable. Human hands are a macroscopic analog of this; every stereogenic center in one has the opposite configuration in the other. Two compounds that are enantiomers of each other have the same physical properties, except for the direction in which they rotate polarized light and how they interact with different optical isomers of other compounds; as a result, different enantiomers of a compound may have different biological effects.

Pure enantiomers exhibit the phenomenon of optical activity and can be separated only with the use of a chiral agent. In nature, only one enantiomer of most chiral biological compounds, such as amino acids, is present. An optically active compound shows two forms: D- form and L- form. Diastereomers are stereoisomers not related through a reflection operation, they are not mirror images of each other. These include meso compounds, cis–trans isomers, E-Z isomers, non-enantiomeric optical isomers. Diastereomers have the same physical properties. In the example shown below, the meso form of tartaric acid forms a diastereomeric pair with both levo and dextro tartaric acids, which form an enantiomeric pair; the D- and L- labeling of the isomers above is not the same as the d- and l- labeling more seen, explaining why these may appear reversed to those familiar with only the latter naming convention. Stereoisomerism about double bonds arises because rotation about the double bond is restricted, keeping the substituents fixed relative to each other.

If the two substituents on at least one end of a double bond are the same there is no stereoisomer and the double bond is not a stereocenter, e.g. propene, CH3CH=CH2 where the two substituents at one end are both H. Traditionally, double bond stereochemistry was described as either cis or trans, in reference to the relative position of substituents on either side of a double bond; the simplest examples of cis-trans isomerism are the 1,2-disubstituted ethenes, like the dichloroethene isomers shown below. Molecule I is cis-1,2-dichloroethene and molecule II is trans-1,2-dichloroethene. Due to occasional ambiguity, IUPAC adopted a more rigorous system wherein the substituents at each end of the double bond are assigned priority based on their atomic number. If the high-priority substituents are on the same side of the bond, it is assigned Z. If they are on opposite sides, it is E. Since chlorine has a larger atomic number than hydrogen, it is the highest-priority group. Using this notation to name the above pictured molecules, molecule I is -1,2-dichloroethene and molecule II is -1,2-dichloroethene.

It is not the case that cis or E and trans are always interchangeable. Consider the following fluoromethylpentene: The proper name for this molecule is either trans-2-fluoro-3-methylpent-2-ene because the alkyl groups that form the backbone chain reside across the double bond from each other, or -2-fluoro-3-methylpent-2-ene because the highest-priority groups on each side of the double bond are on the same side of the double bond. Fluoro is the highest-priority group on the left side of the double bond, ethyl is the highest-priority group on the right side of the molecule; the terms cis and trans are used to describe the relative position of two substituents on a ring. Conformational isomerism is a form of isomerism that describes the phenomenon of molecules with the same structural formula but with different shapes due to rotations about one or more bonds. Different conformations can have different energies, can interconvert, are rarely isolatable. For example, cyclohexane can exist in a variety of different conformations including a chair conformation and a boat conformation, for cyclohexane itself, these can never be separated.

The boat conformation represents the energy maximum on a conformational itinerary between the two equivalent chair forms. There are some molecules that can be isolated in several conformations, due to the large energy barriers between different conformations. 2,2',6,6'-Tetrasubstituted biphenyls can fit into this latter category. Anomerism is an identity for single bonded ring structures where "cis" or "E" and "trans" or "Z" needs to name the substitutions on a carbon atom that displays the identity of chirality. Anomers are named "alpha" or "axial" and "beta" or "equatorial" when substituting a cyclic ring structure that has single bonds between the carbon atoms of the ring for example, a hydroxyl group, a methyl hydroxyl group, a methoxy group or another pyranose or furanose group which are typical single bond substitutions but not limited to these. Axial geometric isomerism will be perpendicular to a reference plane and equatorial will be 120 degrees away from the axial bond or devi

Plains is a village outside the town of Airdrie, in North Lanarkshire, about 14 miles east of Glasgow city centre and 32 miles west of Edinburgh. The nearest major towns are Coatbridge; the village is west of the North Calder Water. The population is about 2,740; the origin of the name "Plains" is unknown. One suggestion is that the name derives from the view afforded to the Cistercian Monks of Newbattle Abbey as they travelled to what is now the site of the village; these monks farmed the wider area for grain in. But the geography of the area runs contrary to this idea. Alternatively, the name may be a contraction of "The Plains of Waterloo" - a name given by a returning soldier from the Napoleonic wars. Either way, it is not uncommon for locals to refer to the village as "The Plains". Plains is situated on the gentle south facing slope of the valley of the North Calder Water, a tributary of the River Clyde. To the north of the settlement runs a series of unclassified roads known to older residents as The Backies.

Opencast mining in the 1970s and 1980s took away much of the natural beauty within this network of roads which since has further been eroded with the advent of a landfill site. The Main Street runs in a straight line for about 1 mile east to west. All of the residential housing of the village lies on the northern side of Main St. forming a square shape. To the south of Main St. the valley drops more steeply down to the North Calder steeply up the other side, home to the parkland Easter Moffat golf course. Plains lies at around 500 ft above sea level. From the nearby Airdriehill Farm, there is a wide vista to the west across the urbanised lower Clyde valley. Beyond, on a clear day, it is possible to see the Isle of Arran. To the south-east of Plains, the land rises to 1000 feet – the highest land in the narrow isthmus across central Scotland spanning the Scottish watershed; the area was chosen as the location for Scotland's first television transmitting stations. The Black Hill Transmitter, at 1000 ft tall, is a prominent local landmark.

It began broadcasting independent Scottish Television services in August 1957. Nearby, but not so tall or prominent, is Kirk o'Shotts transmitter mast, which broadcast Scotland's first BBC television signals in March 1952. There is now a second transmitter which will replace the older one, which itself will be relocated within the Scottish transmitting network; the village was founded in the mid-19th century along. The population of the village in 1860 is recorded at just over 200. Much of the original growth of the village was in keeping with the expansion of the coal mining industry in North Lanarkshire, most notably the Ardenrigg Coal Co Ltd; this coal mining activity dwindled in the second half of the 20th century. However, Scotland's largest opencast coal mine is in operation at Drumshangie Moss, a few miles north-west of Plains. There has been controversy regarding the impact of this mine on the site of the Stanrigg Mining Disaster where, in July 1918, a collapse led to the deaths of 19 local mine workers.

Late 20th century expansion of the village has been to the north of the A89 road in separate developments of local government or Council houses, consisting of blocks of terraced houses. Planned as affordable, rented accommodations for the predominantly working class population, a large percentage have become owner occupied in recent years. At the beginning of the 21st century, a new development of large, detached houses was established in the north-east corner of the village. There is no significant single employer within the village. During the last decades of the 20th century, the main employers were Beechams. Geest occupied a site in the middle of the village, south towards the railway, was involved in the receipt and packaging of fruit for distribution throughout the country; the site is now a timber yard managed by a company called Rowan Timber. The Beecham site was a warehouse and distribution facility employing a number of local drivers and located adjacent to Geest Bananas; the warehouse was demolished and the site is to be developed for additional housing.

Today, Plains is a working class settlement with local people commuting for employment throughout urban central Scotland. There have been recent housing developments; these tend to be more up-market dwellings, are more modern than the council houses which predominate in the village. There has been a new swing park added to Plains and a post office was opened in 2016. A campaign to bring a railway station has not yet been successful. Plains has an active Community Council. Christian worship takes place at Plains Evangelical Church. What is now Plains Evangelical Church, a thriving non-denominational independent church, was begun by Mr Robert McCracken in 1900. St David's Catholic church remains open for worship. There are two state schools: St David's Primary and Plains Primary. Both schools are accommodated in a shared campus built on the former football pitches on the west side of Bruce Street; these football pitches were the former site of pit bings which were only removed as the result of community pressure in the 1960s.

National Cycle Route 75, a Sustrans long distance cycle path, ran parallel and around 100 metres south of Main Street. This was constructed along the bed of a former North British Railway line which had linked Glasgow and Edinburgh. On 10 May 2007, the bill to allowing this line to be re-established as a commuter rai

Lox is a fillet of brined salmon. Lox is one type of salmon product served on a bagel with cream cheese, is garnished with tomato, sliced onion and sometimes capers; the American English word lox is derived from the Yiddish word for salmon, לאַקס laks, which derives from the Germanic word for salmon, *laks-. The word lox has cognates in numerous Germanic languages. For example, cured salmon in Scandinavian countries is known by different versions of the name gravlax or gravad laks, its wide distribution means it existed in its current form in a Proto-Indo-European language. Nova or Nova Scotia salmon, sometimes called Nova lox, is cured with a milder brine and cold-smoked; the name dates from a time. Today, the name refers to the milder brining, as compared to regular lox, the fish may come from other waters or be raised on farms. Scotch or Scottish-style salmon. A mixture of salt and sometimes sugars and other flavorings is applied directly to the meat of the fish; the brine mixture is rinsed off, the fish is cold-smoked.

Nordic-style smoked salmon. The fish is cold-smoked. Gravad lax or gravlax; this is a traditional Nordic means of preparing salmon. The salmon is coated with a spice mixture, which includes dill, sugars and spices like juniper berry, it is served with a sweet mustard-dill sauce. Other similar brined and smoked fish products are popular in delis and fish stores in Chicago and the New York City boroughs, such as chubs, smoked sturgeon, smoked whitefish, kippered herring. Smoked fish Smoked salmon List of smoked foods