Oldest Dryas

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Oldest_Dryas 

 

Alpine valley, like Oldest Dryas

The Oldest Dryas is a biostratigraphic subdivision layer corresponding to an abrupt cooling event, or stadial, which occurred during the last glacial retreat. The time period to which the layer corresponds varies between regions, but it is generally dated as starting at 18.5-17 ka BP and ending 15-14 ka BP. As with the Younger and Older Dryas events, the stratigraphic layer is marked by abundance of the pollen and other remains of Dryas octopetala, an indicator species that colonizes arctic-alpine regions. In the Alps, the Oldest Dryas corresponds to the Gschnitz stadial of the Würm glaciation. The term was originally defined specifically for terrestrial records in the region of Scandinavia, but has come to be used both for ice core stratigraphy in areas across the world and to refer to the time period itself and its associated temporary reversal of the glacial retreat.

Dating

The edge of the ice in Greenland

The period was between 16,050-13,050 BC, from Roberts, 1998. A date from Kilkeel, Northern Ireland, extends the start of the period to as early as 17,050 BC. A strong sequence of carbon-14 dates derived from layered material in the Hauterive/Rouges-Terres excavations on the northwest shore of Lake Neuchâtel in Switzerland, 1992–1993, places the end of the Oldest Dryas at about 12,700 BC, calibrated. The same date from Antarctica and the south China sea is 14,600 and 14,700, respectively, and a Greenland ice core indicates 14,500. David Miles refers to the Oldest Dryas as the last Heinrich event (H1) and dates it to between 16,500 and 14,500 years ago.

The ultimate standard to which all these dates are to be compared is the graph of the oxygen isotope ratio cycles, which gives change in isotope concentration on the y-axis, with time on the x-axis. The graph plots many events that are sharply defined, but others are not. The selection of a terminal point is sometimes partially arbitrary.

The end of the Oldest Dryas is sharply defined. The beginning is a long, gently sloping band, probably no earlier than 17,050 BC, but the date might be set later by approximately 1000 years. Data derived from isotope variation of nitrogen and argon trapped in Greenland ice gives a high-resolution date for the end of the oldest Dryas at the sharp temperature rise of 14.67 ky BP.

Lake Neuchatel

The complete sequence of late Pleistocene climatic periods, defined for Northern Europe, are the Oldest Dryas (stadial), the Bölling (interstadial), the Older Dryas (stadial), the Allerød (interstadial), and the Younger Dryas (stadial). The Holocene begins immediately afterward. The last three are also Blytt-Sernander periods. 

Sometimes, the Older Dryas is missing, as in the Jura Mountains of France, or it is negligible in the evidence. In that case, the initial part of the sequence appears to be Oldest Dryas (cold), Bølling-Allerød (warm), Younger Dryas (cold). The Bølling-Allerød corresponds to the Windermere interstadial in Britain.

Often, however, the apparently-missing Older Dryas is a problem of resolution in the evidence. Some scientists have undertaken high-resolution studies, which combine a variety of climatological methods. They, like the ones conducted on Owens and Mono Lakes, in California, usually detect the Older Dryas. Even when it is detected, it appears to be no more than a few centuries of slightly-cooler weather on the oxygen isotope ratio graph.

Flora

During the Oldest Dryas, Europe was treeless and similar to the Arctic tundra, but much drier and grassier than the modern tundra. It contained shrubs and herbaceous plants such as the following:

• Poaceae, grasses
• Artemisia
• Betula nana, dwarf birch
• Salix retusa, dwarf willow
• Dryas octopetala

• 

  Grassland (Inner Mongolia)
  
• 

  Artemisia vulgaris
  
• 

  Betula nana
  
• 

  Dryas octopetala
  

Fauna

Species were mainly Arctic but during the Glacial Maximum, the warmer weather species had withdrawn into refugia and began to repopulate Europe in the Oldest Dryas. 

The brown bear, Ursos arctos, was among the first to arrive in the north. Genetic studies indicate North European brown bears came from a refugium in the Carpathians of Moldavia. Other refugia were in Italy, Spain and Greece. 

The bears would not have returned north except in pursuit of food. The tundra must already have been well populated. It is likely that the species hunted by humans at Lake Neuchâtel in Switzerland by the end of the period were present during it. Here are other animals present:

Aves

• Gavia arctica, black-throated diver
• Podiceps nigricollis, black-necked grebe
• Cygnus cygnus, whooper swan
• Aquila chrysaetos, golden eagle

• 

  Gavia arctica
  
• 

  Podiceps nigricollis
  
• 

  Cygnus cygnus
  
• 

  Aquila chrysaetos
  

The above birds are primarily maritime. They must have fed in the copious glacial waters of the north that were just beginning to be released.

Fish

• Lota lota, burbot
• Thymallus thymallus, grayling
• Rutilus rutilus, roach
• Salmo trutta, trout
• Salvelinus alpinus, char

• 

  Glacial stream
  
• 

  Lota lota
  
• 

  Salmo trutta
  
• 

  Salvelinus
  

The smaller mammals of the food chain inhabited the herbaceous blanket of the tundra:

Cricetidae

• Discrotonyx torquatus, collared lemming
• Microtus oeconomus, root vole
• Microtus arvalis, common vole
• Chionmys nivalis, snowy vole

Leporidae

• Lepus timidus, Arctic hare

Sciuridae

• Marmota marmota, marmot

• 

  Microtus oeconomus
  
• 

  Microtus arvalis
  
• 

  Lepus timidus
  
• 

  Marmota marmota
  

In addition to bears and birds were other predators of the following small animals:

Carnivora

• Felis lynx, lynx
• Alopex lagopus, Arctic fox
• Canis lupus, wolf

• 

  Lynx (or Felis) lynx
  
• 

  Alopex lagopus
  
• 

  Canis lupus
  
• 

  Icelandic horse, perhaps like Equus ferus
  

Humans were interested in the large mammals, which included:

• Rangifer tarandus, reindeer
• Equus ferus, wild horse
• Capra ibex, ibex

At some point, the larger mammals arrived: hyena, woolly rhinoceros, cave bear and mammoth.

• 

  Rangifer tarandus
  
• 

  Capra ibex
  
• 

  Woolly rhinoceros
  
• 

  Mammoth
  

Human prehistory

Jōmon pottery

Human cultures in Europe were Upper Palaeolithic and belonged to Cro-Magnon man. Neanderthals had long since disappeared by replacement or amalgamation with Homo sapiens. The Magdalenian culture of reindeer hunters prevailed in Western Europe. From the Carpathians eastward, the Epigravettian continued the prior Gravettian. In Japan, the Jōmon culture had already become sedentary and was producing some food, and possibly grew rice, but it was not at all urban. It was manufacturing the first known pottery.

One of the most remarkable discoveries of the period was the domestic wolf, a distinct breed of Canis lupus, with smaller teeth. The domestic dog, Canis familiaris, also has been found. It is thought that the animals helped with the hunting, but they would, by the nature of the hunt, have gradually become adept at herding.

Older Dryas

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Older_Dryas 

 

The Older Dryas was a stadial (cold) period between the Bølling and Allerød interstadials (warmer phases), about 14,000 years Before Present), towards the end of the Pleistocene. Its date is not well defined, with estimates varying by 400 years, but its duration is agreed to have been around 200 years.

The gradual warming since the Last Glacial Maximum (27,000 to 24,000 years BP) has been interrupted by two cold spells: the Older Dryas and the Younger Dryas (c. 12,900-11,650 BP). In northern Scotland, the glaciers were thicker and deeper during the Older Dryas than the succeeding Younger Dryas, and there is no evidence of human occupation of Britain. In Northwestern Europe was also an earlier Oldest Dryas (18.5-17 ka BP-15-14 ka BP). The Dryas are named after an indicator genus, the Arctic and Alpine plant Dryas, the remains of which are found in higher concentrations in deposits from colder periods.

The Older Dryas was a variable cold, dry Blytt-Sernander period, observed in climatological evidence in only some regions, depending on latitude. In regions in which it is not observed, the Bølling-Allerød is considered a single interstadial period. Evidence of the Older Dryas is strongest in northern Eurasia, particularly part of Northern Europe, roughly equivalent to Pollen zone Ic.

Dates

In the Greenland oxygen isotope record, the Older Dryas appears as a downward peak establishing a small, low-intensity gap between the Bølling and the Allerød. That configuration presents a difficulty in estimating its time, as it is more of a point than a segment. The segment is small enough to escape the resolution of most carbon-14 series, as the points are not close enough together to find the segment.

One approach to the problem assigns a point and then picks an arbitrary segment. The Older Dryas is sometimes considered to be "centered" near 14,100 BP or to be 100 to 150 years long "at" 14,250 BP.

A second approach finds carbon-14 or other dates as close to the end of the Bølling and the beginning of the Allerød as possible and then selects endpoints that based on them: for example, 14,000-13,700 BP.

The best approach attempts to include the Older Dryas in a sequence of points as close together as possible (high resolution) or within a known event.

For example, pollen from the island of Hokkaidō, Japan, records a Larix pollen peak and matching sphagnum decline at 14,600-13700 BP. In the White Sea, a cooling occurred at 14,700-13,400/13,000, which resulted in a re-advance of the glacier in the initial Allerød. In Canada, the Shulie Lake phase, a re-advance, is dated to 14,000-13,500 BP. On the other hand, varve chronology in southern Sweden indicates a range of 14,050-13,900 BP.

Capturing the Older Dryas by high resolution continues to be of interest to climatologists.

Description

Northern Europe offered an alternation of steppe and tundra environments depending on the permafrost line and the latitude. In moister regions, around lakes and streams, were thickets of dwarf birch, willow, sea buckthorn, and juniper. In the river valleys and uplands, to the south, were open birch forests.

The first trees, birch and pine, had spread into Northern Europe 500 years earlier. During the Older Dryas, the glacier re-advanced, and the trees retreated southward, to be replaced by a mixture of grassland and cool-weather alpine species. The biome has been called "Park Tundra," "Arctic tundra," "Arctic pioneer vegetation," or “birch woodlands." It is now in the transition between taiga and tundra in Siberia. Then, it stretched from Siberia to Great Britain, in a more-or-less unbroken expanse. 

To the northwest was the Baltic ice lake, which was truncated by the edge of the glacier. Species had access to Denmark and southern Sweden. Most of Finland and the Baltic countries were under the ice or the lake for most of the period. Northern Scandinavia was glaciated. Between Britain and the Continental Europe were rolling hills prolifically populated with animals. Thousands of specimens, hundreds of tons of bones, have been recovered from the bottom of the North Sea, called "Doggerland," and they continue to be recovered.

There are many more species found for the period than in this article. Most families were more diverse than they are today, and they were yet more so in the last interglacial. A great extinction, especially of mammals, continued throughout the end of the Pleistocene, and it may be continuing today.

Evidence

The Older Dryas is a period of cooling during the Bølling-Allerød warming, estimated to be from 13,900 to 13,600 years before present (BP), and the estimated ages can vary using different age dating methods. Numerous studies on chronology and palaeoclimate of last deglaciation show a cooling event within Bølling-Allerød warming that reflects the occurrence of Older Dryas. The determination of paleotemperatures varies from study to study depending on the sample collected. δ¹⁸O measurements are most common when analyzing Ice core samples whereas the changing abundance pattern of fauna and flora are most commonly used when examining lake sediments. Moraine belts are usually studied in places with palaeoglacier presented. As for ocean sediments, the variations of alkenone levels and faunal abundances were measured to model paleotemperatures in separate studies showed in the following sections.

Ice core δ¹⁸O evidence

The North Greenland Ice Core Project (GRIP) members drilled an undisturbed ice core from North Greenland (75.1 8N, 42.3 8W). The ice core record showed a cold oscillation between 14,025 to13,904 years BP, which is reflected in the increased δ¹⁸O during this period. This cold oscillation was also observed in earlier ice core records (GRIP^[8][9] and GISP2) drilled in early 1990s by GRIP members.

Lake sediment evidence

A multi-proxy study on late glacial lake sediments of Moervaart palaeolake shows multiple pieces of evidence in various aspects to support Older Dryas.

The lake sediment had an erosional surface prior to Older Dryas suggesting a change to colder climate. Microstructure observation of the sediments shows that fossil soil wedges or frost cracks were observed in the top of Older Dryas deposits, which indicates mean annual air temperatures below -1 to 0 ℃ and cold winters. This conclusion is also supported by the presence of Juniperus, which indicates a protecting snow cover in winter. This change is also shown on the records at the Rieme sites on the Great SandRidge of Maldegem-Stekene at Snellegem in NW Belgium, and many other sites in north-western Europe.

δ¹⁸O measurements show a decreasing trend in δ¹⁸O at the transition to the Older Dryas, which corresponds to the ice core record of precipitation in the northern hemisphere.

Pollen analysis shows a temporary decrease in the pollen levels of trees and shrubs with a short-term increase of herbaceous pollen. The changed pollen pattern suggests an increased abundance of grass as well as a retreat of tree and shrubs. The change of vegetation distribution further indicates a colder and drier climate during this period. As for aquatic plant evidence, both aquatic and semi-aquatic botanical taxa show a sharp decrease, suggesting lower lake levels caused by drier climate. The drier climate is also reflected by increased salinity indicated by diatom analysis.

The change of Chironomids population also indicates a colder climate. Microtendipes is an indicator of intermediate temperature in Late glacial deposits in northern Europe (Brooks and Birks, 2001). The abundance of Microtendipes peaked in the early part of Older Dryas suggesting a cold oscillation. The mollusc data (Valvata piscinalis as a cold-water indicator) suggests a lower summer temperature comparing to previous Bølling period.

Ocean sediment evidence

Recent research on sea surface temperature (SST) for the past 15,000 years in southern Okinawa modelled the Paleoclimate of ocean sediment core (ODP 1202B) using an alkenone analysis. The results show a cooling stage at 14,300 to 13,700 years BP between Bølling and Allerød warm phases, corresponding to the Older Dryas event.

Another study on an ocean sediment core from Norwegian Trench also suggests a cooling between Bølling and Allerød warm phases. The glacial polar faunal study on ocean sediment core Troll 3.1 based on Neogloboquadrina pachyderma abundances suggests that there were two cooling events before Younger Dryas in which one of the events occurred within Bølling-Allerød interstadial and can be associated with Older Dryas.

Moraine evidence

The study on late-glacial climate change in White Mountains (New Hampshire, USA) refined the deglaciation history of White Mountain Moraine System (WMMS) by mapping moraine belts and related lake sequences. The result suggests that the Littleton-Bethlehem (L-B) readvance of ice sheet occurred between 14,000 and 13,800 years BP. The L-B readvance coincided with the Older Dryas events and provides the first well-documented and dated evidence of Older Dryas.

Another Glacial chronology and palaeoclimate study on moraine suggests a cold oscillation in the second late-glacial (LG2) following the first late-glacial readvance (LG1) at around 14,000±700 to 13,700±1200 years BP. The LG2 cold oscillation around 14,000 years BP can correspond to the cooling of Greenland Interstadial 1 (GI-1d-Older Dryas) that happened around the same time period, which is the first chronological evidence that supports the presence of Older Dryas in the Tatra Mountains.

Flora

Older Dryas species are usually found in sediment below the bottom layer of the bog. Indicator species are the Alpine plants:

• Betula pubescens or downy birch (Central Europe);
• Pinaceae or pine family (Poland);
• Dryas octopetala, or dryas;
• Salix herbacea, or dwarf willow;
• Oxyria digyna, or mountain sorrel.

Grasslands species are the following:

• Artemisia, sagebrush or wormwood;
• Ephedra, or joint-fir.
• Hippophae

Fauna

A well-stocked biozone prevailed on the Arctic plains and thickets of the Late Pleistocene. Plains mammals were most predominant:

Artiodactyls:

• Bison priscus, the steppe wisent or steppe bison
• Rangifer tarandus, the reindeer or caribou
• Megaloceros giganteus, the Irish elk
• Alces alces, the elk
• Cervus elaphus, the red deer
• Ovibos moschatus, the musk ox
• Saiga tatarica, the saiga

Perissodactyls:

• Equus ferus, the wild horse. Many authors refer to it as Equus caballus, but the latter term is most correctly reserved for the domestic horse. Ferus is presumed to be one or more ancestral or related stocks to caballus and has been described as "caballine".
• Coelodonta antiquitatis, woolly rhinoceros

Proboscidea:

• Mammuthus primigenius, the woolly mammoth

So much meat on the hoof must have supported large numbers of Carnivora: Ursidae:

• Ursus arctos, the brown bear
• Ursus spelaeus, the cave bear

Hyaenidae:

• Crocuta crocuta, the spotted hyena

Felidae:

• Panthera spelaea, the cave lion

Canidae:

• Canis lupus, the wolf
• Alopex lagopus, the Arctic fox

Mustelidae:

• Gulo gulo, the wolverine

The sea also had its share of carnivores; their maritime location made them survive until modern times: Phocidae:

• Pagophilus groenlandica, the harp seal
• Pusa hispida, the ringed seal

Odobenidae:

• Odobenus rosmarus, the walrus

Of the Cetacean Odontoceti, the Monodontidae:

• Delphinapterus leucas, the beluga

Delphinidae:

• Orcinus orca, the killer whale

Of the Mysticetian Eschrichtiidae:

• Eschrictius robustus, the gray whale

The top of the food chain was supported by larger numbers of smaller animals farther down, which lived in the herbaceous blanket covering the tundra or steppe and helped maintain it by carrying seeds, manuring and aerating it.

Leporidae:

• Lepus tanaiticus, the hare

Ochotonidae:

• Ochotona spelaeus, the pika

Cricetidae:

• Lemmus obensis, Siberian lemming
• Dicrostonix, collared lemming
• Lagurus lagurus, steppe lemming
• Microtus gregalis, narrow-headed vole
• Arvicola terrestris, water vole

Sciuridae:

• Spermophilus, ground squirrel

Dipodidae:

• Allactaga jaculus, the jerboa

Humans

Eurasia was populated by Homo sapiens sapiens (Cro-Magnon man) during the late Upper Paleolithic. Bands of humans survived by hunting the mammals of the plains. In Northern Europe they preferred reindeer, in Ukraine the woolly mammoth. They sheltered in huts and manufactured tools around campfires. Ukrainian shelters were supported by mammoth tusks. Humans were already established across Siberia and in North America.

Two domestic dogs (Canis familiaris) have been found in late Pleistocene Ukraine and were a heavy breed, similar to a Great Dane, perhaps useful to run down Elephantidae. The large number of mammoth bones at campsites make it clear that even then, the Elephantidae in Europe were approaching the limit of their duration. Their bones were used for many purposes, one being the numerous objects of art, including an engraved star map.

Late Upper Palaeolithic culture was by no means uniform. Many local traditions have been defined. The Hamburgian culture had occupied the lowlands and Northern Germany before the Older Dryas. During the Older Dryas, contemporaneous with the Havelte Group of the late Hamburgian, the Federmesser culture appeared and occupied Denmark and southern Sweden, following the reindeer. South of the Hamburgian was the longstanding Magdalenian. In Ukraine was the Moldovan, which used tusks to build shelters.

Wax

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Wax

Cetyl palmitate, a typical wax ester.

 

Commercial honeycomb foundation, made by pressing beeswax between patterned metal rollers.

 

Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give low viscosity liquids. Waxes are insoluble in water but soluble in organic, nonpolar solvents. Natural waxes of different types are produced by plants and animals and occur in petroleum.

Chemistry

Ceroline brand wax for floors and furniture, first half of 20th century. From the Museo del Objeto del Objeto collection

Waxes are organic compounds that characteristically consist of long alkyl chains. Natural waxes may contain unsaturated bonds and include various functional groups such as fatty acids, primary and secondary alcohols, ketones, aldehydes and fatty acid esters, and aromatic compounds may also be present. Synthetic waxes often consist of homologous series of long-chain aliphatic hydrocarbons (alkanes or paraffins) that lack functional groups.

Plant and animal waxes

Waxes are synthesized by many plants and animals. Those of animal origin typically consist of wax esters derived from a variety of fatty acids and carboxylic alcohols. In waxes of plant origin, characteristic mixtures of unesterified hydrocarbons may predominate over esters. The composition depends not only on species, but also on geographic location of the organism.

Animal waxes

The best known animal wax is beeswax used in constructing the honeycombs of honeybees, but other insects secrete waxes. A major component of the beeswax is myricyl palmitate which is an ester of triacontanol and palmitic acid. Its melting point is 62-65 °C. Spermaceti occurs in large amounts in the head oil of the sperm whale. One of its main constituents is cetyl palmitate, another ester of a fatty acid and a fatty alcohol. Lanolin is a wax obtained from wool, consisting of esters of sterols.

Plant waxes

Plants secrete waxes into and on the surface of their cuticles as a way to control evaporation, wettability and hydration. The epicuticular waxes of plants are mixtures of substituted long-chain aliphatic hydrocarbons, containing alkanes, alkyl esters, fatty acids, primary and secondary alcohols, diols, ketones, aldehydes. From the commercial perspective, the most important plant wax is carnauba wax, a hard wax obtained from the Brazilian palm Copernicia prunifera. Containing the ester myricyl cerotate, it has many applications, such as confectionery and other food coatings, car and furniture polish, floss coating, and surfboard wax. Other more specialized vegetable waxes include jojoba oil, candelilla wax and ouricury wax.

Modified plant and animal waxes

Plant and animal based waxes or oils can undergo selective chemical modifications to produce waxes with more desirable properties than are available in the unmodified starting material. This approach has relied on green chemistry approaches including olefin metathesis and enzymatic reactions and can be used to produce waxes from inexpensive starting materials like vegetable oils.

Petroleum derived waxes

Although many natural waxes contain esters, paraffin waxes are hydrocarbons, mixtures of alkanes usually in a homologous series of chain lengths. These materials represent a significant fraction of petroleum. They are refined by vacuum distillation. Paraffin waxes are mixtures of saturated n- and iso- alkanes, naphthenes, and alkyl- and naphthene-substituted aromatic compounds. A typical alkane paraffin wax chemical composition comprises hydrocarbons with the general formula C_nH_2n+2, such as hentriacontane, C₃₁H₆₄. The degree of branching has an important influence on the properties. Microcrystalline wax is a lesser produced petroleum based wax that contains higher percentage of isoparaffinic (branched) hydrocarbons and naphthenic hydrocarbons.

Millions of tons of paraffin waxes are produced annually. They are used in foods (such as chewing gum and cheese wrapping), in candles and cosmetics, as non-stick and waterproofing coatings and in polishes.

Montan wax

Montan wax is a fossilized wax extracted from coal and lignite. It is very hard, reflecting the high concentration of saturated fatty acids and alcohols. Although dark brown and odorous, they can be purified and bleached to give commercially useful products.

Polyethylene and related derivatives

As of 1995, about 200 million kilograms/y were consumed.

Polyethylene waxes are manufactured by one of three methods: 1- direct polymerization of ethylene (may include co -monomers also); 2- thermal degradation of high molecular weight polyethylene resin; 3- recovery of low molecular weight fractions from high molecular weight resin production.

Each production technique generates products with slightly different properties. Key properties of low molecular weight polyethylene waxes are viscosity, density and melt point.

Polyethylene waxes produced by means of degradation or recovery from polyethylene resin streams contain very low molecular weight materials that must be removed to prevent volatilization and potential fire hazards during use. Polyethylene waxes manufactured by this method are usually stripped of low molecular weight fractions to yield a flash point > 500°F(> 260°C). Many polyethylene resin plants produce a low molecular weight stream often referred to as Low Polymer Wax (LPW). LPW is unrefined and contains volatile oligomers, corrosive catalyst and may contain other foreign material and water. Refining of LPW to produce a polyethylene wax involves removal of oligomers and hazardous catalyst. Proper refining of LPW to produce polyethylene wax is especially important when being used in applications requiring FDA or other regulatory certification.

Uses

Waxes are mainly consumed industrially as components of complex formulations, often for coatings. The main use of polyethylene and polypropylene waxes is in the formulation of colourants for plastics. Waxes confer matting effects and wear resistance to paints. Polyethylene waxes are incorporated into inks in the form of dispersions to decrease friction. They are employed as release agents, find use as slip agents in furniture, and confer corrosion resistance.

Candles

Wax candle.

Waxes such as paraffin wax or beeswax, and hard fats such as tallow are used to make candles, used for lighting and decoration.

Wax products

Waxes are used as finishes and coatings for wood products. Beeswax is frequently used as a lubricant on drawer slides where wood to wood contact occurs.

Other uses

A lava lamp is a novelty item that contains wax melted from below by a bulb. The wax rises and falls in decorative, molten blobs.

Sealing wax was used to close important documents in the Middle Ages. Wax tablets were used as writing surfaces. There were different types of wax in the Middle Ages, namely four kinds of wax (Ragusan, Montenegro, Byzantine, and Bulgarian), "ordinary" waxes from Spain, Poland, and Riga, unrefined waxes and colored waxes (red, white, and green). Waxes are used to make wax paper, impregnating and coating paper and card to waterproof it or make it resistant to staining, or to modify its surface properties. Waxes are also used in shoe polishes, wood polishes, and automotive polishes, as mold release agents in mold making, as a coating for many cheeses, and to waterproof leather and fabric. Wax has been used since antiquity as a temporary, removable model in lost-wax casting of gold, silver and other materials.

Wax with colorful pigments added has been used as a medium in encaustic painting, and is used today in the manufacture of crayons, china markers and colored pencils. Carbon paper, used for making duplicate typewritten documents was coated with carbon black suspended in wax, typically montan wax, but has largely been superseded by photocopiers and computer printers. In another context, lipstick and mascara are blends of various fats and waxes colored with pigments, and both beeswax and lanolin are used in other cosmetics. Ski wax is used in skiing and snowboarding. Also, the sports of surfing and skateboarding often use wax to enhance the performance.

Some waxes are considered food-safe and are used to coat wooden cutting boards and other items that come into contact with food. Beeswax or coloured synthetic wax is used to decorate Easter eggs in Romania, Ukraine, Poland, Lithuania and the Czech Republic. Paraffin wax is used in making chocolate covered sweets.

Wax is also used in wax bullets, which are used as simulation aids.

Specific examples

Animal waxes

• Beeswax - produced by honey bees
• Chinese wax - produced by the scale insect Ceroplastes ceriferus
• Lanolin (wool wax) - from the sebaceous glands of sheep
• Shellac wax - from the lac insect Kerria lacca
• Spermaceti - from the head cavities and blubber of the sperm whale

Vegetable waxes

• Bayberry wax - from the surface wax of the fruits of the bayberry shrub, Myrica faya
• Candelilla wax - from the Mexican shrubs Euphorbia cerifera and Euphorbia antisyphilitica
• Carnauba wax - from the leaves of the Carnauba palm, Copernicia cerifera
• Castor wax - catalytically hydrogenated castor oil
• Esparto wax - a byproduct of making paper from esparto grass, (Macrochloa tenacissima)
• Japan wax - a vegetable triglyceride (not a true wax), from the berries of Rhus and Toxicodendron species
• Jojoba oil - a liquid wax ester, from the seed of Simmondsia chinensis.
• Ouricury wax - from the Brazilian feather palm, Syagrus coronata.
• Rice bran wax - obtained from rice bran (Oryza sativa)
• Soy wax - from soybean oil
• Tallow Tree wax - from the seeds of the tallow tree Triadica sebifera.

Mineral waxes

• Ceresin waxes
• Montan wax - extracted from lignite and brown coal
• Ozocerite - found in lignite beds
• Peat waxes

Petroleum waxes

• Paraffin wax - made of long-chain alkane hydrocarbons
• Microcrystalline wax - with very fine crystalline structure

Royal jelly

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Royal_jelly

Developing queen larvae surrounded by royal jelly

Royal jelly is a honey bee secretion that is used in the nutrition of larvae, as well as adult queens. It is secreted from the glands in the hypopharynx of nurse bees, and fed to all larvae in the colony, regardless of sex or caste.

During the process that a hive is creating new queens, the workers construct special queen cells. The larvae in these cells are fed with copious amounts of royal jelly. This type of feeding triggers the development of queen morphology, including the fully developed ovaries needed to lay eggs.

Royal jelly is widely marketed as a dietary supplement. It is an alternative medicine that falls under the category of apitherapy. Both the European Food Safety Authority and United States Food and Drug Administration have concluded that the current evidence does not support the claim of health benefits, and have actively discouraged the sale and consumption of the jelly. In the United States, the Food and Drug Administration has taken legal action against companies that have used unfounded claims of health benefits to market royal jelly products. There have also been documented cases of allergic reactions, namely hives, asthma, and anaphylaxis, due to consumption of royal jelly.

Production

Royal jelly is secreted from the glands in the heads of worker bees and is fed to all bee larvae, whether they are destined to become drones (males), workers (sterile females), or queens (fertile females). After three days, the drone and worker larvae are no longer fed with royal jelly, but queen larvae continue to be fed this special substance throughout their development.

Composition

Royal jelly is 67% water, 12.5% protein, 11% simple sugars (monosaccharides), 6% fatty acids and 3.5% 10-hydroxy-2-decenoic acid (10-HDA). It also contains trace minerals, antibacterial and antibiotic components, pantothenic acid (vitamin B₅), pyridoxine (vitamin B₆) and trace amounts of vitamin C, but none of the fat-soluble vitamins: A, D, E or K.

Proteins

Major royal jelly proteins (MRJPs) are a family of proteins secreted by honey bees. The family consists of nine proteins, of which MRJP1 (also called royalactin), MRJP2, MRJP3, MRJP4, and MRJP5 are present in the royal jelly secreted by worker bees. MRJP1 is the most abundant, and largest in size. The five proteins constitute 83–90% of the total proteins in royal jelly. Royal jelly has been used in traditional medicine since ancient times, and the MRJPs are shown to be the main medicinal components. They are synthesised by a family of nine genes (mrjp genes), which are in turn members of the yellow family of genes such as in the fruitfly (Drosophila) and bacteria. They are attributed to be involved in differential development of queen larva and worker larvae, thus establishing division of labour in the bee colony.

Epigenetic effects

The honey bee queens and workers represent one of the most striking examples of environmentally controlled phenotypic polymorphism. Even if two larvae had identical DNA, one raised to be a worker, the other a queen, the two adults would be strongly differentiated across a wide range of characteristics including anatomical and physiological differences, longevity, and reproductive capacity. Queens constitute the female sexual caste and have large active ovaries, whereas female workers have only rudimentary, inactive ovaries and are functionally sterile. The queen–worker developmental divide is controlled epigenetically by differential feeding with royal jelly; this appears to be due specifically to the protein royalactin. A female larva destined to become a queen is fed large quantities of royal jelly; this triggers a cascade of molecular events resulting in development of a queen. It has been shown that this phenomenon is mediated by an epigenetic modification of DNA known as CpG methylation. Silencing the expression of an enzyme that methylates DNA in newly hatched larvae led to a royal jelly-like effect on the larval developmental trajectory; the majority of individuals with reduced DNA methylation levels emerged as queens with fully developed ovaries. This finding suggests that DNA methylation in honey bees allows the expression of epigenetic information to be differentially altered by nutritional input.

Use by humans

Royal jelly is collected and sold as a dietary supplement for humans, but the European Food Safety Authority has concluded that the current evidence does not support the claim that consuming royal jelly will give health benefits in humans. In the United States, the Food and Drug Administration has taken legal action against companies that have used unfounded claims of health benefits to market royal jelly products.

Cultivation

Royal jelly is harvested by stimulating colonies with movable frame hives to produce queen bees. Royal jelly is collected from each individual queen cell (honeycomb) when the queen larvae are about four days old. These are the only cells in which large amounts are deposited; when royal jelly is fed to worker larvae, it is fed directly to them, and they consume it as it is produced, while the cells of queen larvae are "stocked" with royal jelly much faster than the larvae can consume it. Therefore, only in queen cells is the harvest of royal jelly practical. A well-managed hive during a season of 5–6 months can produce approximately 500 g of royal jelly. Since the product is perishable, producers must have immediate access to proper cold storage (e.g., a household refrigerator or freezer) in which the royal jelly is stored until it is sold or conveyed to a collection center. Sometimes honey or beeswax is added to the royal jelly, which is thought to aid its preservation.

Adverse effects

Royal jelly may cause allergic reactions in humans ranging from hives, asthma, to even fatal anaphylaxis. The incidence of allergic side effects in people who consume royal jelly is unknown. The risk of having an allergy to royal jelly is higher in people who have other allergies.