Vores Øl (Danish for Our Beer) is presented as the first open source beer. Today also known as Free Beer. The recipe is published under a Creative Commons license. The beer was created by students at the IT-University in Copenhagen together with Superflex, a Copenhagen-based artist collective, to illustrate how open source concepts might be applied outside the digital world. The students brewed the first 100 litre batch, titled 'version 1.0', of the dark heavy beer in the school cafeteria, and created label designs and a website to promote the beer and publish the recipe.
Recipe
The following recipe is as shown on the official website (As of September 2005), although other variants may exist due to the freedom given to modify the recipe.
Recipe for approximately 85 l (approximately 6% alcohol by volume).
Malt extract
Four types of malted barley are used:
6 kg pilsner malt
4 kg münsner malt
1 kg caramel malt
1 kg lager malt
The malt is crushed and put in 55–60 °C hot water for 1–2 hours.
The mash is filtered and the liquid now contains about 10 kg malt extract.
Taste and sugar
50 g Hallertauer (Northern Brewer) hops
60 g Tettnang hops
300 g guarana beans (Guarana beans can typically be bought at health food stores).
4 kg sugar
The malt extract is brought to a boil in a large pot with Hallertauer NB hops and approximately 70 l (18.5 gal) of water.
After half an hour, the guarana beans and sugar are added.
The mixture simmers for about an hour, the heat is turned off, and the Tettnang hops are added and left to sit for 10 minutes. The mixture is then filtered and cooled in a sealed container.
Fermentation
Yeast is added and the beer is fermented at room temperature for approximately 2 weeks.
When the beer is fully fermented, it is transferred to bottles. First 4 g sugar is added per liter and some yeast from the bottom of the fermentation tanks for priming.
The beer is then left in the bottles at room temperature for 8-10 days for carbonation.
source :
http://www.superflex.net/projects/freebeer/
http://freebeer.org
Saturday, March 24, 2007
Friday, March 23, 2007
Molecular Nanobot in Various Uses
In Japan photo-reactive nanocrystals are being developed for more efficient solar cell production. Rice University is developing methods that use the reactivity of nanoparticles to clean contaminants, especially biological contaminants from water. In agriculture, nano-sensors will be sprinkled on crops or soil to monitor temperature, water, salinity, nitrogen and disease. Robert Freitas is developing an artificial red blood cell able to deliver 236 times more oxygen to tissues than natural red blood cells. Freitas predicts his device will be used to treat anaemia and lung disorders, but also will enhance human performance in sport and warfare. Researchers at the Florida University have created a nanocapsule gel to deliver drugs into the eyes through soft contact lenses.
The importance of nanotechnology to the future of mankind cannot be overstated. Nanotech’s promise is clean industries, cures for disease, nearly unlimited energy supplies, a continuance of Moore’s Law, the end of hunger, and the elmination of aging. Welcome to Molecular Nanobots.
There is so much to explore once you start exploring within nanotechnology - you'll quickly find that the all aspects of the very small - end up being very, very large
source :- http://www.molecularnanobots.com/
The importance of nanotechnology to the future of mankind cannot be overstated. Nanotech’s promise is clean industries, cures for disease, nearly unlimited energy supplies, a continuance of Moore’s Law, the end of hunger, and the elmination of aging. Welcome to Molecular Nanobots.
There is so much to explore once you start exploring within nanotechnology - you'll quickly find that the all aspects of the very small - end up being very, very large
source :- http://www.molecularnanobots.com/
Tuesday, March 20, 2007
Virtual Lab From ChemCollective
The Virtual Laboratory from the ChemCollective is a new personal favorite. The online version is a java applet, but they now have a downloadable version that will run on any Windows desktop computer. The software allows a student or instructor to simulate many lab activities. Acid base titration, buffer chemistry, limiting reactant stoichiometry and solution equilibria are but a few of the simulations that are possible with this software. There is also an Authoring Program that allows instructors to design their own lab activities and add their own reagents.
If you have java virtual machine installed than download the 1 MBversion or else download the 12 MB version
Download 12 MB With Java Plugin
Download 1 MB (Without JAVA)
If you have java virtual machine installed than download the 1 MBversion or else download the 12 MB version
Download 12 MB With Java Plugin
Download 1 MB (Without JAVA)
Friday, March 16, 2007
Potato Battery
If you thought that potatoes were only good for eating than you are wrong . Potatoes can also be used as low voltage battey and to prove this i will teach you to light a low voltage bulb with a potato battery .
Things you need : 2 potatoes (obviously) , glavanized zinc nails , copper wire , low voltage bulb
step 1 : Insert the galvanized nail to the ends of each potato .
step 2: Insert the copper wire to the other end of the patato keeping it as far as possible from the nail
step 3: Join the copper wire from the first potato to the nail in second potato so that we have a connection in series
step 4: connect (any device) the bulb to the terminals (the copper terminal act as positive and the zinc act as negative)
The chemistry behind this is simple . The potatoes contain phospheric acid whis allows the electrons to flow from copper to zinc . This means that if you would use fruit like lemons or oranges instead of potatoe the battery would still work . A single potato produces about 0.5 volt of current .
Try experimenting with other low voltage devices or by adding more potatoes for more power
Do not eat the potatoes after using them for batteries .
Things you need : 2 potatoes (obviously) , glavanized zinc nails , copper wire , low voltage bulb
step 1 : Insert the galvanized nail to the ends of each potato .
step 2: Insert the copper wire to the other end of the patato keeping it as far as possible from the nail
step 3: Join the copper wire from the first potato to the nail in second potato so that we have a connection in series
step 4: connect (any device) the bulb to the terminals (the copper terminal act as positive and the zinc act as negative)
The chemistry behind this is simple . The potatoes contain phospheric acid whis allows the electrons to flow from copper to zinc . This means that if you would use fruit like lemons or oranges instead of potatoe the battery would still work . A single potato produces about 0.5 volt of current .
Try experimenting with other low voltage devices or by adding more potatoes for more power
Do not eat the potatoes after using them for batteries .
Artificial Snow
Once upon a time, making snow was a straightforward craft. One could simply grind up large blocks of ice and spread the pulverized material where desired or use a basic stand-in material such as cellulose powder or bits of paper. Nowadays, with the advent of better materials and machinery--and because the fluffy white stuff fascinates people to no end--there are myriad ways to pull off a big snow job for indoor or outdoor use using machine-made snow or artificial snow.
Machine-made snow has been substantially refined by the ski industry over the years. Snowmaking serves to extend the ski season or can rescue a dry winter, but it also has become important for controlling snow conditions as the number of skiers has increased and the mode of enjoying the slopes has evolved to include tubing, sledding, and snowboarding. Machine snow is also used in labs to learn how to forecast avalanches.
To make snow, water cooled to just above its freezing point is pumped under high pressure through the nozzles of a "snow gun." Compressed air or electric fans are usually used to help atomize the water into fine droplets and to disperse them over a wide area where they hopefully will freeze before they hit the ground. If not, the snow will be too wet. Other ways to make snow include using a combination of water and compressed air that is frozen by liquid nitrogen, a method used primarily for indoor sports centers. Snow also can be made from carbon dioxide.
Critical to snowmaking for skiing is getting the right combination of temperature and humidity--the lower the humidity, the higher the outdoor temperature can be to form snow. With untreated water, an air temperature of about –8 °C (18 °F) is needed. Another important factor is the need to generate sufficient nucleation sites for ice crystals to form. Nucleation sites can be a few water molecules that coalesce alone; calcium, magnesium, or other ions; or an impurity such as a clay particle or organic matter.
When the temperature isn't quite cold enough--above about –5 °C (23 °F)--snowmakers need little helpers in the form of seed materials added to the water to generate nucleation sites. Silver iodide, kaolin, soaps and detergents, and fungi or lichens are among the materials that have been used.
Currently, the most popular additive is Snomax, a freeze-dried protein powder sold by York Snow, Victor, N.Y. Snomax is derived from Pseudomonas syringae, a common bacterium found on grasses, trees, and vegetable crops. In the 1970s, plant pathologists studying the frost sensitivity of corn plants at the University of Wisconsin, Madison, discovered that the bacteria were responsible for initializing ice crystallization [Nature, 262, 282 (1976)].
A newer seeding product taking the market by storm is called Drift, a liquid polyether-substituted trisiloxane produced by Aquatrols in Cherry Hill, N.J. Drift works as a surfactant to decrease the level of hydrogen bonding in water so the water can freeze more quickly, according to the company.
When it comes to artificial snow, ice, or frost, there are more than 100 different materials that can be used, according to Snow Business, a U.K.-based company that supplies ersatz snow for movie sets. Different classes of materials include paper, plastic, starch and cellulose, or foam.
On movie sets, several products generally will be used in combination or with machine-made snow to create the desired effect. Machine snow is usually avoided because it melts and doesn't look flaky when it's falling. Paper, starch, and cellulose are good materials for falling snow. They can be sprinkled down onto a scene and kept aloft by fans blowing air from the edges of the set. A problem with fans, however, is that the noise may interfere with dialogue. During snow scenes there often will be no dialogue, only music, or the dialogue will be dubbed over.
Paper is one of the most versatile materials because it's weatherproof. Starch and cellulose can give the effect of a light dusting of snow or frost on plants and the ground, but they can be slippery to walk on and can generate a sticky mess. Shredded plastic snow is good for small-scale uses in a studio, although it's more expensive. Firefighting foam works well for deep snow and is fast and inexpensive to use, but it can't be walked on.
A favored material is instant mashed potato flakes. From a distance, the flake snow looks pretty real. The drawback: If it starts raining or the ground somehow gets wet, there's mashed potato slush to slog through. Also, in a close-up shot, potato flakes look like potato flakes, and on moist lips they could present a problem--pass the gravy!
One final type of artificial snow is called dryslope. This is a group of wood, metal, or plastic materials, usually laid down as latticework with void spaces, that is used to ski on out of season or in regions where it does not snow. One downside is the hard materials can lead to a greater risk of injury.
A newer type of dryslope that aims to curb injuries is a multilayer polymer composite matting that resembles carpeting. Two products are Snowflex, made by Briton Engineering Developments, Yorkshire, England, and Powderpak, made by an Atlanta-based company with the same name.
Snowflex, for example, has a slippery polybutylene terephthalate fiber surface layer that sits atop a shock-absorbing pad that has a woven backing. Water piped through the layers exits recessed nozzles and mists the surface, which helps reduce friction even further. This new type of dryslope can be laid out like carpet and cut to fit features such as moguls. It has been used indoors and outdoors to make half pipes and short slopes for freestyle (acrobatic) or downhill skiing and snowboarding.
January 19,2004
Volume 82, Number 03
CENEAR 82 03 p. 72
ISSN 0009-2347
STEVE RITTER
Machine-made snow has been substantially refined by the ski industry over the years. Snowmaking serves to extend the ski season or can rescue a dry winter, but it also has become important for controlling snow conditions as the number of skiers has increased and the mode of enjoying the slopes has evolved to include tubing, sledding, and snowboarding. Machine snow is also used in labs to learn how to forecast avalanches.
To make snow, water cooled to just above its freezing point is pumped under high pressure through the nozzles of a "snow gun." Compressed air or electric fans are usually used to help atomize the water into fine droplets and to disperse them over a wide area where they hopefully will freeze before they hit the ground. If not, the snow will be too wet. Other ways to make snow include using a combination of water and compressed air that is frozen by liquid nitrogen, a method used primarily for indoor sports centers. Snow also can be made from carbon dioxide.
Critical to snowmaking for skiing is getting the right combination of temperature and humidity--the lower the humidity, the higher the outdoor temperature can be to form snow. With untreated water, an air temperature of about –8 °C (18 °F) is needed. Another important factor is the need to generate sufficient nucleation sites for ice crystals to form. Nucleation sites can be a few water molecules that coalesce alone; calcium, magnesium, or other ions; or an impurity such as a clay particle or organic matter.
When the temperature isn't quite cold enough--above about –5 °C (23 °F)--snowmakers need little helpers in the form of seed materials added to the water to generate nucleation sites. Silver iodide, kaolin, soaps and detergents, and fungi or lichens are among the materials that have been used.
Currently, the most popular additive is Snomax, a freeze-dried protein powder sold by York Snow, Victor, N.Y. Snomax is derived from Pseudomonas syringae, a common bacterium found on grasses, trees, and vegetable crops. In the 1970s, plant pathologists studying the frost sensitivity of corn plants at the University of Wisconsin, Madison, discovered that the bacteria were responsible for initializing ice crystallization [Nature, 262, 282 (1976)].
A newer seeding product taking the market by storm is called Drift, a liquid polyether-substituted trisiloxane produced by Aquatrols in Cherry Hill, N.J. Drift works as a surfactant to decrease the level of hydrogen bonding in water so the water can freeze more quickly, according to the company.
When it comes to artificial snow, ice, or frost, there are more than 100 different materials that can be used, according to Snow Business, a U.K.-based company that supplies ersatz snow for movie sets. Different classes of materials include paper, plastic, starch and cellulose, or foam.
On movie sets, several products generally will be used in combination or with machine-made snow to create the desired effect. Machine snow is usually avoided because it melts and doesn't look flaky when it's falling. Paper, starch, and cellulose are good materials for falling snow. They can be sprinkled down onto a scene and kept aloft by fans blowing air from the edges of the set. A problem with fans, however, is that the noise may interfere with dialogue. During snow scenes there often will be no dialogue, only music, or the dialogue will be dubbed over.
Paper is one of the most versatile materials because it's weatherproof. Starch and cellulose can give the effect of a light dusting of snow or frost on plants and the ground, but they can be slippery to walk on and can generate a sticky mess. Shredded plastic snow is good for small-scale uses in a studio, although it's more expensive. Firefighting foam works well for deep snow and is fast and inexpensive to use, but it can't be walked on.
A favored material is instant mashed potato flakes. From a distance, the flake snow looks pretty real. The drawback: If it starts raining or the ground somehow gets wet, there's mashed potato slush to slog through. Also, in a close-up shot, potato flakes look like potato flakes, and on moist lips they could present a problem--pass the gravy!
One final type of artificial snow is called dryslope. This is a group of wood, metal, or plastic materials, usually laid down as latticework with void spaces, that is used to ski on out of season or in regions where it does not snow. One downside is the hard materials can lead to a greater risk of injury.
A newer type of dryslope that aims to curb injuries is a multilayer polymer composite matting that resembles carpeting. Two products are Snowflex, made by Briton Engineering Developments, Yorkshire, England, and Powderpak, made by an Atlanta-based company with the same name.
Snowflex, for example, has a slippery polybutylene terephthalate fiber surface layer that sits atop a shock-absorbing pad that has a woven backing. Water piped through the layers exits recessed nozzles and mists the surface, which helps reduce friction even further. This new type of dryslope can be laid out like carpet and cut to fit features such as moguls. It has been used indoors and outdoors to make half pipes and short slopes for freestyle (acrobatic) or downhill skiing and snowboarding.
January 19,2004
Volume 82, Number 03
CENEAR 82 03 p. 72
ISSN 0009-2347
STEVE RITTER
Flash Perodic Table
Bored with the usual looking perodic table . Check out this cool flash version of the perodic table . You can get all sorts of informations on the elemnts on this perodic table .
Give it a try >>>>
Give it a try >>>>
Monday, March 12, 2007
Open Cola
OpenCola is a brand of cola unique in that the instructions for making it are freely available and modifiable. Anybody can make the drink, and anyone can modify and improve on the recipe as long as they, too, license their recipe under the GNU General Public License. The legal grounds for this are dubious however, as recipes are exempted from copyright as they are techniques, not artworks.
Although originally intended as a promotional tool to explain free software/open source software, the drink took on a life of its own and 150,000 cans were sold. The Toronto-based company Opencola founded by Grad Conn, Cory Doctorow and John Henson became better known for the drink than the software it was supposed to promote. Laird Brown, the company's senior strategist, attributes its success to a widespread mistrust of big corporations and the "proprietary nature of almost everything."
Flavouring formula
* 10.0 g food-grade gum arabic
* 3.50 mL orange oil
* 3.00 mL water
* 2.75 mL lime oil
* 1.25 mL cassia oil
* 1.00 mL lemon oil
* 1.00 mL nutmeg oil
* 0.25 mL coriander oil
* 0.25 mL neroli oil
* 0.25 mL lavender oil
Concentrate formula
* 2.36 kg plain granulated white table sugar
* 2.28 L water
* 30.0 mL caramel colour
* 3.50 tsp. 75% phosphoric acid or citric acid
* 2.00 tsp. flavouring formula
* 0.50 tsp. caffeine (optional)
Beverage formula
Mix the concentrate with 5 parts filtered water and force carbonate the beverage, or use a soda fountain that will combine the concentrate with carbonated water at the tap.
Some members of the free software movement have started an Italian OpenCola project, but without any commercial purpose. The only thing the Italian OpenCola and the "official" OpenCola have in common is the name. The Italian version is clear and has never been sold.
recipe for making open cola -> http://www.colawp.com/colas/400/cola467_recipe.html
or download the formula -> http://upload.wikimedia.org/wikipedia/commons/b/bf/OpenCola_soft_drink_recipe.pdf
Although originally intended as a promotional tool to explain free software/open source software, the drink took on a life of its own and 150,000 cans were sold. The Toronto-based company Opencola founded by Grad Conn, Cory Doctorow and John Henson became better known for the drink than the software it was supposed to promote. Laird Brown, the company's senior strategist, attributes its success to a widespread mistrust of big corporations and the "proprietary nature of almost everything."
Flavouring formula
* 10.0 g food-grade gum arabic
* 3.50 mL orange oil
* 3.00 mL water
* 2.75 mL lime oil
* 1.25 mL cassia oil
* 1.00 mL lemon oil
* 1.00 mL nutmeg oil
* 0.25 mL coriander oil
* 0.25 mL neroli oil
* 0.25 mL lavender oil
Concentrate formula
* 2.36 kg plain granulated white table sugar
* 2.28 L water
* 30.0 mL caramel colour
* 3.50 tsp. 75% phosphoric acid or citric acid
* 2.00 tsp. flavouring formula
* 0.50 tsp. caffeine (optional)
Beverage formula
Mix the concentrate with 5 parts filtered water and force carbonate the beverage, or use a soda fountain that will combine the concentrate with carbonated water at the tap.
Some members of the free software movement have started an Italian OpenCola project, but without any commercial purpose. The only thing the Italian OpenCola and the "official" OpenCola have in common is the name. The Italian version is clear and has never been sold.
recipe for making open cola -> http://www.colawp.com/colas/400/cola467_recipe.html
or download the formula -> http://upload.wikimedia.org/wikipedia/commons/b/bf/OpenCola_soft_drink_recipe.pdf
Tuesday, March 06, 2007
Why do we assume that other beings must be based on carbon? Why couldn't organisms be based on other substances?
Aurthor :- Joseph Lazio
[A portion of this entry is based on a lecture by Alain Leger (IAS) at
the SPIE Astronomical Telescopes and Instrumentation 2000 Conference.]
As far as SETI, the search for extraterrestrial intelligence, is
concerned, we do not assume that other being must be based on carbon.
In fact, SETI is a bit of a misnomer. We are searching for
extraterrestrial *technological* intelligences, technological
intelligences capable of broadcasting their existence over
interstellar distances. Whether the technological civilizations is
based on carbon or some other substance is largely irrelevant. (Of
course, one might worry that intelligences based on some substance
other than carbon might have such different perspectives on the
Universe that, even if they broadcast electromagnetic radiation, they
would do so in a fashion that we would never consider.)
However, when one moves to finding life on other bodies in the solar
system or traces of life on extrasolar planets, there is a definite
carbon chauvinism in our thinking. The most commonly mentioned
alternate to carbon (C) is silicon (Si). It has similar chemical
properties as C, lying just below C in the periodic table of the
elements.
Carbon chauvinism has arisen because C is able to form quite
complicated molecules, in part because its atomic structure is such
that C can bond with up to four other elements. Not only can it bond
with up to four other elements, but C can form multiple bonds with
other elements, particularly itself. (Atoms bond by sharing
electrons, when two atoms share more than one electron they have a
multiple bond. For instance, water is formed by an oxygen atom
sharing the two electrons from two hydrogen atoms. In contrast, there
are many C compounds in which a single C atom shares multiple
electrons with other atom.)
A clear indication of the versatility of C is found in interstellar
chemistry. Interstellar chemistry typically occurs on the surface of
microscopic dust grains contained with large clouds of gas between the
stars. The physical conditions are much different than anything on
the surface of a habitable planet. Nonetheless, of the molecules
identified in interstellar space as of 1998, 84 are based on C and 8
are based on Si. Moreover of the eight Si-based compounds, 4 also
include C.
Thus, while there is definitely a C bias in our thinking, there is at
least some evidence from Nature supporting this bias.
[A portion of this entry is based on a lecture by Alain Leger (IAS) at
the SPIE Astronomical Telescopes and Instrumentation 2000 Conference.]
As far as SETI, the search for extraterrestrial intelligence, is
concerned, we do not assume that other being must be based on carbon.
In fact, SETI is a bit of a misnomer. We are searching for
extraterrestrial *technological* intelligences, technological
intelligences capable of broadcasting their existence over
interstellar distances. Whether the technological civilizations is
based on carbon or some other substance is largely irrelevant. (Of
course, one might worry that intelligences based on some substance
other than carbon might have such different perspectives on the
Universe that, even if they broadcast electromagnetic radiation, they
would do so in a fashion that we would never consider.)
However, when one moves to finding life on other bodies in the solar
system or traces of life on extrasolar planets, there is a definite
carbon chauvinism in our thinking. The most commonly mentioned
alternate to carbon (C) is silicon (Si). It has similar chemical
properties as C, lying just below C in the periodic table of the
elements.
Carbon chauvinism has arisen because C is able to form quite
complicated molecules, in part because its atomic structure is such
that C can bond with up to four other elements. Not only can it bond
with up to four other elements, but C can form multiple bonds with
other elements, particularly itself. (Atoms bond by sharing
electrons, when two atoms share more than one electron they have a
multiple bond. For instance, water is formed by an oxygen atom
sharing the two electrons from two hydrogen atoms. In contrast, there
are many C compounds in which a single C atom shares multiple
electrons with other atom.)
A clear indication of the versatility of C is found in interstellar
chemistry. Interstellar chemistry typically occurs on the surface of
microscopic dust grains contained with large clouds of gas between the
stars. The physical conditions are much different than anything on
the surface of a habitable planet. Nonetheless, of the molecules
identified in interstellar space as of 1998, 84 are based on C and 8
are based on Si. Moreover of the eight Si-based compounds, 4 also
include C.
Thus, while there is definitely a C bias in our thinking, there is at
least some evidence from Nature supporting this bias.
Alternative biochemistry
Alternative biochemistry is the speculative biochemistry of alien life forms that differ radically from those on Earth. It includes biochemistries that use atoms other than carbon to construct primary cellular structures and/or use solvents besides water. Theories about extraterrestrial life based on alternative biochemistries is common in science fiction.
Atoms other than carbon
Scientists have speculated about the pros and cons of using atoms other than carbon to form the molecular structures necessary for life, but no one has proposed a theory employing such atoms to form all the molecular machinery necessary for life. Since humans are carbon-based beings and have never encountered any life that has evolved outside the earth’s environment, excluding the possibility of all other elements may be considered carbon chauvinism.
Silicon biochemistry
The most commonly proposed basis for an alternative biochemical system is the silicon atom, since silicon has many chemical properties similar to carbon and is in the same periodic table group, the carbon group.
But silicon has a number of handicaps as a carbon alternative. Because silicon atoms are much bigger, having a larger mass and atomic radius, they have difficulty forming double or triple covalent bonds, which are important for a biochemical system. Silanes, which are chemical compounds of hydrogen and silicon that are analogous to the alkane hydrocarbons, are highly reactive with water, and long-chain silanes spontaneously decompose. Molecules incorporating polymers of alternating silicon and oxygen atoms instead of direct bonds between silicon, known collectively as silicones, are much more stable. It has been suggested that silicone-based chemicals would be more stable than equivalent hydrocarbons in a sulphuric-acid-rich environment, as is found in some extraterrestrial locations. In general, however, complex long-chain silicone molecules are still more unstable than their carbon counterparts.
Another obstacle is that silicon dioxide (a common ingredient of many sands), the analog of carbon dioxide, is a non-soluble solid at the temperature range where water is liquid, making it difficult for silicon to be introduced into water-based biochemical systems even if the necessary range of biochemical molecules could be constructed out of it.
Finally, of the varieties of molecules identified in the interstellar medium as of 1998, 84 are based on carbon and 8 are based on silicon. Moreover, of those 8 compounds, four also include carbon within them. This suggests a greater variety of complex carbon compounds throughout the cosmos, providing less of a foundation upon which to build silicon-based biologies. The cosmic abundance of carbon to silicon is roughly 10 to 1.
The Earth, as well as other terrestrial planets, is exceptionally silicon-rich and carbon-poor. However, terrestrial life is carbon-based. Rare carbon proved to be much more successful as a life base than abundant silicon.
It is possible, however, that silicon compounds may be biologically useful under certain exotic environmental conditions, either in conjunction with or in a role less directly analogous to carbon. A simple real-world example is the silicate skeletal structure of diatoms. See biogenic silica.
A. G. Cairns-Smith has proposed that the first living organisms to exist were clay minerals - which were probably based on silicon.
Nitrogen and phosphorus biochemistry
Nitrogen and phosphorus also offer possibilities as the basis for biochemical molecules. Like carbon, phosphorus can form long chain molecules on its own, which would potentially allow it to form complex macromolecules if it were not so reactive. However, in combination with nitrogen, it can form much more stable covalent bonds and create a wide range of molecules, including rings.
Earth's atmosphere is approximately 78% nitrogen, but this would probably not be of much use to a phosphorus-nitrogen (P-N) lifeform since molecular nitrogen (N2) is nearly inert and energetically expensive to "fix" due to its triple bond. (On the other hand, certain Earth plants such as legumes can fix nitrogen using symbiotic anaerobic bacteria contained in their root nodules.) A nitrogen dioxide (NO2) or ammonia (NH3) atmosphere would be more useful. Nitrogen also forms a number of oxides, such as nitrogen monoxide, dinitrogen oxide, and dinitrogen tetraoxide, and all would be present in a nitrogen-dioxide-rich atmosphere.
In a nitrogen dioxide atmosphere, P-N plant analogues could absorb nitrogen dioxide from the air and phosphorus from the ground. The nitrogen dioxide would be reduced, with analogues to sugar being produced in the process, and waste oxygen would be released into the atmosphere. Animals based on phosphorus and nitrogen would consume the plants, use atmospheric oxygen to metabolize the sugar analogues, exhaling nitrogen dioxide and depositing phosphorus, or phosphorus-rich material, as solid waste.
In an ammonia atmosphere, P-N plants would absorb ammonia from the air and phosphorus from the ground, then oxidize the ammonia to produce P-N sugars and release hydrogen waste. P-N animals are now the reducers, breathing in hydrogen and converting the P-N sugars to ammonia and phosphorus. This is the opposite pattern of oxidation and reduction from a nitrogen dioxide world, and indeed from the known biochemistry of Earth. It would be analogous to Earth's atmospheric carbon supply being in the form of methane instead of carbon dioxide.
Debate continues, as several aspects of a phosphorus-nitrogen cycle biology would be energy deficient. Also, nitrogen and phosphorus are unlikely to occur in the ratios and quantity required in the real universe. Carbon, being preferentially formed during nuclear fusion, is more abundant and is more likely to end up in a preferred location.
Other exotic biochemical elements
Arsenic, which is chemically similar to phosphorus, while poisonous for most Earth life, is incorporated into the biochemistry of some organisms. Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Both arsenate reduction and arsenite oxidation have been observed in microbes. Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy.
Chlorine is sometimes proposed as a biological alternative to oxygen, either in carbon-based biologies or hypothetical non-carbon-based ones. But chlorine is much less abundant than oxygen in the universe, and so it is unlikely that a planet will be able to form which has a large enough concentration of chlorine available on its surface to form the basis of a biochemistry. Chlorine will instead likely be bound up in the form of salts and other inert compounds.
Sulfur is also able to form long-chain molecules, but suffers from the same high reactivity problems that phosphorus and silanes do. The biological use of sulfur as an alternative to carbon is purely theoretical, but strains of sulfur-reducing bacteria have been discovered in exotic locations on earth, and also not so exotic locations, such as aging water systems. These bacteria can utilize elemental sulfur instead of oxygen, reducing sulfur to hydrogen sulfide. Examples of this type of metabolism are green sulfur bacteria and purple sulfur bacteria.
Non-water solvents
In addition to carbon compounds, all currently known terrestrial life also requires water as a solvent. It is sometimes assumed that water is the only suitable chemical to fill this role. Some of the properties of water that are important for life processes include a large temperature range over which it is liquid, a high heat capacity useful for temperature regulation, a large heat of vaporization, and the ability to dissolve a wide variety of compounds. There are other chemicals with similar properties that have sometimes been proposed as alternatives.
Ammonia
Ammonia is perhaps the most commonly proposed alternative. Numerous chemical reactions are possible in an ammonia solution, and liquid ammonia has some chemical similarities with water. Ammonia can dissolve most organic molecules at least as well as water does, and in addition it is capable of dissolving many elemental metals. Given this set of chemical properties it has been theorized that ammonia-based life forms might be possible.
However, ammonia does have some problems as a basis for life. The hydrogen bonds between ammonia molecules are weaker than those in water, causing ammonia's heat of vaporization to be half that of water, its surface tension to be three times smaller, and reducing its ability to concentrate non-polar molecules through a hydrophobic effect. For these reasons, science questions how well ammonia could hold prebiotic molecules together in order to allow the emergence of a self-reproducing system. Ammonia is also combustible and oxidizable and could not exist sustainably in a biosphere that oxidizes it. It would, however, be stable in a reducing environment.
A biosphere based on ammonia would likely exist at temperatures or air pressures that are extremely unusual for terrestrial life. Terrestrial life usually exists within the melting point and boiling point of water at normal pressure, between 0°C (273 K) and 100°C (373 K); at normal pressure ammonia's melting and boiling points are between −78°C (195 K) and −33°C (240 K). Such extremely cooled temperatures create problems, as they slow biochemical reactions tremendously and may cause biochemical precipitation out of solution due to high melting points. Ammonia could be a liquid at normal temperatures, but at much higher pressures; for example, at 60 atm, ammonia melts at −77°C (196 K) and boils at 98°C (371 K).
Ammonia and ammonia-water mixtures remain liquid at temperatures far below the freezing point of pure water, so such biochemistries might be well suited to planets and moons orbiting outside the water-based "habitability zone". Such conditions could exist, for example, under the surface of Saturn's largest moon Titan.
Hydrogen Flouride
Hydrogen flouride like water is a polar molecule, and due to its polarity it can dissolve many ionic compounds. It's melting point is -84°C and its boiling point is 19.54°C, the difference between the two is more than 100°C. HF also hydrogen bonds with its neighbor molecules as do water and ammonia. All of these things make HF a candidate to host life on other planets.
Not much research has been done on liquid HF in regards to its ability to dissolve and react with non-polar molecules. It is possible that the biota in an HF ocean could use the flourine as an electron acceptor to photosynthesize energy.
Other solvents
Other solvents sometimes proposed include methanol, hydrogen sulfide and hydrogen chloride. The latter two suffer from a relatively low cosmic abundance of sulfur and chlorine, which tend to be bound up in solid minerals. A mixture of hydrocarbons, such as the methane/ethane seas once believed to exist on the surface of Titan, could act as a solvent over a wide range of temperatures but would lack polarity. Isaac Asimov, the biochemist and science fiction writer, suggested that poly-lipids could form a substitute for proteins in a non-polar solvent such as methane or liquid hydrogen. Other solvents such as formamide might also be suitable as a solvent that would support alternative biochemistry.
source :- wikipedia
Atoms other than carbon
Scientists have speculated about the pros and cons of using atoms other than carbon to form the molecular structures necessary for life, but no one has proposed a theory employing such atoms to form all the molecular machinery necessary for life. Since humans are carbon-based beings and have never encountered any life that has evolved outside the earth’s environment, excluding the possibility of all other elements may be considered carbon chauvinism.
Silicon biochemistry
The most commonly proposed basis for an alternative biochemical system is the silicon atom, since silicon has many chemical properties similar to carbon and is in the same periodic table group, the carbon group.
But silicon has a number of handicaps as a carbon alternative. Because silicon atoms are much bigger, having a larger mass and atomic radius, they have difficulty forming double or triple covalent bonds, which are important for a biochemical system. Silanes, which are chemical compounds of hydrogen and silicon that are analogous to the alkane hydrocarbons, are highly reactive with water, and long-chain silanes spontaneously decompose. Molecules incorporating polymers of alternating silicon and oxygen atoms instead of direct bonds between silicon, known collectively as silicones, are much more stable. It has been suggested that silicone-based chemicals would be more stable than equivalent hydrocarbons in a sulphuric-acid-rich environment, as is found in some extraterrestrial locations. In general, however, complex long-chain silicone molecules are still more unstable than their carbon counterparts.
Another obstacle is that silicon dioxide (a common ingredient of many sands), the analog of carbon dioxide, is a non-soluble solid at the temperature range where water is liquid, making it difficult for silicon to be introduced into water-based biochemical systems even if the necessary range of biochemical molecules could be constructed out of it.
Finally, of the varieties of molecules identified in the interstellar medium as of 1998, 84 are based on carbon and 8 are based on silicon. Moreover, of those 8 compounds, four also include carbon within them. This suggests a greater variety of complex carbon compounds throughout the cosmos, providing less of a foundation upon which to build silicon-based biologies. The cosmic abundance of carbon to silicon is roughly 10 to 1.
The Earth, as well as other terrestrial planets, is exceptionally silicon-rich and carbon-poor. However, terrestrial life is carbon-based. Rare carbon proved to be much more successful as a life base than abundant silicon.
It is possible, however, that silicon compounds may be biologically useful under certain exotic environmental conditions, either in conjunction with or in a role less directly analogous to carbon. A simple real-world example is the silicate skeletal structure of diatoms. See biogenic silica.
A. G. Cairns-Smith has proposed that the first living organisms to exist were clay minerals - which were probably based on silicon.
Nitrogen and phosphorus biochemistry
Nitrogen and phosphorus also offer possibilities as the basis for biochemical molecules. Like carbon, phosphorus can form long chain molecules on its own, which would potentially allow it to form complex macromolecules if it were not so reactive. However, in combination with nitrogen, it can form much more stable covalent bonds and create a wide range of molecules, including rings.
Earth's atmosphere is approximately 78% nitrogen, but this would probably not be of much use to a phosphorus-nitrogen (P-N) lifeform since molecular nitrogen (N2) is nearly inert and energetically expensive to "fix" due to its triple bond. (On the other hand, certain Earth plants such as legumes can fix nitrogen using symbiotic anaerobic bacteria contained in their root nodules.) A nitrogen dioxide (NO2) or ammonia (NH3) atmosphere would be more useful. Nitrogen also forms a number of oxides, such as nitrogen monoxide, dinitrogen oxide, and dinitrogen tetraoxide, and all would be present in a nitrogen-dioxide-rich atmosphere.
In a nitrogen dioxide atmosphere, P-N plant analogues could absorb nitrogen dioxide from the air and phosphorus from the ground. The nitrogen dioxide would be reduced, with analogues to sugar being produced in the process, and waste oxygen would be released into the atmosphere. Animals based on phosphorus and nitrogen would consume the plants, use atmospheric oxygen to metabolize the sugar analogues, exhaling nitrogen dioxide and depositing phosphorus, or phosphorus-rich material, as solid waste.
In an ammonia atmosphere, P-N plants would absorb ammonia from the air and phosphorus from the ground, then oxidize the ammonia to produce P-N sugars and release hydrogen waste. P-N animals are now the reducers, breathing in hydrogen and converting the P-N sugars to ammonia and phosphorus. This is the opposite pattern of oxidation and reduction from a nitrogen dioxide world, and indeed from the known biochemistry of Earth. It would be analogous to Earth's atmospheric carbon supply being in the form of methane instead of carbon dioxide.
Debate continues, as several aspects of a phosphorus-nitrogen cycle biology would be energy deficient. Also, nitrogen and phosphorus are unlikely to occur in the ratios and quantity required in the real universe. Carbon, being preferentially formed during nuclear fusion, is more abundant and is more likely to end up in a preferred location.
Other exotic biochemical elements
Arsenic, which is chemically similar to phosphorus, while poisonous for most Earth life, is incorporated into the biochemistry of some organisms. Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Both arsenate reduction and arsenite oxidation have been observed in microbes. Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy.
Chlorine is sometimes proposed as a biological alternative to oxygen, either in carbon-based biologies or hypothetical non-carbon-based ones. But chlorine is much less abundant than oxygen in the universe, and so it is unlikely that a planet will be able to form which has a large enough concentration of chlorine available on its surface to form the basis of a biochemistry. Chlorine will instead likely be bound up in the form of salts and other inert compounds.
Sulfur is also able to form long-chain molecules, but suffers from the same high reactivity problems that phosphorus and silanes do. The biological use of sulfur as an alternative to carbon is purely theoretical, but strains of sulfur-reducing bacteria have been discovered in exotic locations on earth, and also not so exotic locations, such as aging water systems. These bacteria can utilize elemental sulfur instead of oxygen, reducing sulfur to hydrogen sulfide. Examples of this type of metabolism are green sulfur bacteria and purple sulfur bacteria.
Non-water solvents
In addition to carbon compounds, all currently known terrestrial life also requires water as a solvent. It is sometimes assumed that water is the only suitable chemical to fill this role. Some of the properties of water that are important for life processes include a large temperature range over which it is liquid, a high heat capacity useful for temperature regulation, a large heat of vaporization, and the ability to dissolve a wide variety of compounds. There are other chemicals with similar properties that have sometimes been proposed as alternatives.
Ammonia
Ammonia is perhaps the most commonly proposed alternative. Numerous chemical reactions are possible in an ammonia solution, and liquid ammonia has some chemical similarities with water. Ammonia can dissolve most organic molecules at least as well as water does, and in addition it is capable of dissolving many elemental metals. Given this set of chemical properties it has been theorized that ammonia-based life forms might be possible.
However, ammonia does have some problems as a basis for life. The hydrogen bonds between ammonia molecules are weaker than those in water, causing ammonia's heat of vaporization to be half that of water, its surface tension to be three times smaller, and reducing its ability to concentrate non-polar molecules through a hydrophobic effect. For these reasons, science questions how well ammonia could hold prebiotic molecules together in order to allow the emergence of a self-reproducing system. Ammonia is also combustible and oxidizable and could not exist sustainably in a biosphere that oxidizes it. It would, however, be stable in a reducing environment.
A biosphere based on ammonia would likely exist at temperatures or air pressures that are extremely unusual for terrestrial life. Terrestrial life usually exists within the melting point and boiling point of water at normal pressure, between 0°C (273 K) and 100°C (373 K); at normal pressure ammonia's melting and boiling points are between −78°C (195 K) and −33°C (240 K). Such extremely cooled temperatures create problems, as they slow biochemical reactions tremendously and may cause biochemical precipitation out of solution due to high melting points. Ammonia could be a liquid at normal temperatures, but at much higher pressures; for example, at 60 atm, ammonia melts at −77°C (196 K) and boils at 98°C (371 K).
Ammonia and ammonia-water mixtures remain liquid at temperatures far below the freezing point of pure water, so such biochemistries might be well suited to planets and moons orbiting outside the water-based "habitability zone". Such conditions could exist, for example, under the surface of Saturn's largest moon Titan.
Hydrogen Flouride
Hydrogen flouride like water is a polar molecule, and due to its polarity it can dissolve many ionic compounds. It's melting point is -84°C and its boiling point is 19.54°C, the difference between the two is more than 100°C. HF also hydrogen bonds with its neighbor molecules as do water and ammonia. All of these things make HF a candidate to host life on other planets.
Not much research has been done on liquid HF in regards to its ability to dissolve and react with non-polar molecules. It is possible that the biota in an HF ocean could use the flourine as an electron acceptor to photosynthesize energy.
Other solvents
Other solvents sometimes proposed include methanol, hydrogen sulfide and hydrogen chloride. The latter two suffer from a relatively low cosmic abundance of sulfur and chlorine, which tend to be bound up in solid minerals. A mixture of hydrocarbons, such as the methane/ethane seas once believed to exist on the surface of Titan, could act as a solvent over a wide range of temperatures but would lack polarity. Isaac Asimov, the biochemist and science fiction writer, suggested that poly-lipids could form a substitute for proteins in a non-polar solvent such as methane or liquid hydrogen. Other solvents such as formamide might also be suitable as a solvent that would support alternative biochemistry.
source :- wikipedia
Cambridge Scientists Produce Live Video Showing How Carbon Nanotubes Form
A Cambridge University-led team of scientists have successfully produced live video footage that shows how carbon nanotubes, more than 10,000 times smaller in diameter than a human hair, form.
The video sequences show nanofibres and nanotubes nucleating around miniscule particles of nickel and are already offering greater insight into how these microscopic structures self-assemble. The films can be viewed on the Cambridge University website at:
http://www.admin.cam.ac.uk/news/special/20070301/
In particular, the team discovered that the carbon network is guided into tubular shape by a drastic restructuring of the nickel – the catalyst in the process. They were also able to track and time the deposition of the carbon around the nickel.
Carbon nanotubes are new building blocks enabling engineers to improve and further miniaturise everyday electronic devices like computers or mobile phones. At the moment scientists can grow nanotubes but cannot accurately control their structure.
Being able to do so is vital as it is the very structure of a nanotube that dictates its properties. The nano-scale video observations mean that scientists will be able to better understand the nucleation of nanotubes and are therefore an important step on the route towards application.
The two sequences show action taking place in real time on an astonishingly small scale. The difference in size between a single-walled nanotube and a human hair is close to the difference between the same human hair and the Eiffel Tower. The microscopic scale involved has, in the past, made it difficult to understand the growth process.
The team used X-rays produced at a synchrotron (a type of particle accelerator) and a modified high-resolution transmission electron microscope to observe and film a process called catalytic chemical vapour deposition. This is one of several methods of producing nanotubes, and involves the application of a gas containing carbon (in this case acetylene) to minute crystalline droplets referred to as “catalyst islands” (the nickel).
As the gas is applied carbon sticks to the catalyst islands forming layers of graphite. In conditions appropriate to creating nanofibres, the nickel particle was pushed upwards in a series of peristaltic movements as the carbon continued to deposit on its sides. At several points the nickel formed a cap which almost “popped” out of the forming tube, leaving a layer of graphite behind it. This process is called “bambooing”, because the resultant carbon nanofibre is a cylinder containing several cavities, each one separated by one of these graphite layers, similar in form to bamboo. Throughout the whole process, the nickel remained crystalline rather than liquid.
The team then looked at conditions more appropriate to producing single-walled carbon nanotubes, which involved less acetylene. The catalyst is not squeezed upwards. Instead, a cap of carbon formed on the top of the nickel, and gradually extended from it to form a tubular structure. The catalyst island was squeezed and reshaped by this process and was moulded by the carbon forming around it rather than retaining its original form.
Dr Stephan Hofmann, who led the research, said: “In order to reach the full application potential for nanotubes, we need to be able to accurately control their growth first. As a manifestation of the impressive progress of nanometrology, we are actually now able to watch molecular objects grow. This new video footage shows that the catalyst itself remains crystalline but is constantly changing its shape as the carbon network is formed around it.
“We cannot yet solve the problem of not being able to self-assemble carbon nanotubes with well-defined characteristics, but we have discovered that if we are to do so, we need to be mindful not just of the carbon dynamics but the changing shape of the catalyst as well.”
source :- http://www.cam.ac.uk
The video sequences show nanofibres and nanotubes nucleating around miniscule particles of nickel and are already offering greater insight into how these microscopic structures self-assemble. The films can be viewed on the Cambridge University website at:
http://www.admin.cam.ac.uk/news/special/20070301/
In particular, the team discovered that the carbon network is guided into tubular shape by a drastic restructuring of the nickel – the catalyst in the process. They were also able to track and time the deposition of the carbon around the nickel.
Carbon nanotubes are new building blocks enabling engineers to improve and further miniaturise everyday electronic devices like computers or mobile phones. At the moment scientists can grow nanotubes but cannot accurately control their structure.
Being able to do so is vital as it is the very structure of a nanotube that dictates its properties. The nano-scale video observations mean that scientists will be able to better understand the nucleation of nanotubes and are therefore an important step on the route towards application.
The two sequences show action taking place in real time on an astonishingly small scale. The difference in size between a single-walled nanotube and a human hair is close to the difference between the same human hair and the Eiffel Tower. The microscopic scale involved has, in the past, made it difficult to understand the growth process.
The team used X-rays produced at a synchrotron (a type of particle accelerator) and a modified high-resolution transmission electron microscope to observe and film a process called catalytic chemical vapour deposition. This is one of several methods of producing nanotubes, and involves the application of a gas containing carbon (in this case acetylene) to minute crystalline droplets referred to as “catalyst islands” (the nickel).
As the gas is applied carbon sticks to the catalyst islands forming layers of graphite. In conditions appropriate to creating nanofibres, the nickel particle was pushed upwards in a series of peristaltic movements as the carbon continued to deposit on its sides. At several points the nickel formed a cap which almost “popped” out of the forming tube, leaving a layer of graphite behind it. This process is called “bambooing”, because the resultant carbon nanofibre is a cylinder containing several cavities, each one separated by one of these graphite layers, similar in form to bamboo. Throughout the whole process, the nickel remained crystalline rather than liquid.
The team then looked at conditions more appropriate to producing single-walled carbon nanotubes, which involved less acetylene. The catalyst is not squeezed upwards. Instead, a cap of carbon formed on the top of the nickel, and gradually extended from it to form a tubular structure. The catalyst island was squeezed and reshaped by this process and was moulded by the carbon forming around it rather than retaining its original form.
Dr Stephan Hofmann, who led the research, said: “In order to reach the full application potential for nanotubes, we need to be able to accurately control their growth first. As a manifestation of the impressive progress of nanometrology, we are actually now able to watch molecular objects grow. This new video footage shows that the catalyst itself remains crystalline but is constantly changing its shape as the carbon network is formed around it.
“We cannot yet solve the problem of not being able to self-assemble carbon nanotubes with well-defined characteristics, but we have discovered that if we are to do so, we need to be mindful not just of the carbon dynamics but the changing shape of the catalyst as well.”
source :- http://www.cam.ac.uk
Monday, March 05, 2007
Electrochemical Uses Of Carbon
Carbon is one of the most abundant elements found on earth. It occurs freely in crystalline forms such as diamond and graphite.The diamond crystal is cubic, with the atoms arranged in a tetrahedral configuration. This arrangement of carbon atoms produces a solid that is the hardest known substance. Consequently, it is used as an industrial abrasive. In addition, diamond has a very high refractive index, hence it produces brilliant cut gems. Graphite, on the other hand, is soft, has a hexagonal structure, with the carbon atoms arranged in layer planes. The spacing between the layer planes in graphite is 0.3354 nm (nm = billionth of a meter). This layer structure facilitates easy cleavage along the planes, which makes it desirable as a solid lubricant. There are variations of the graphite structure. When the dimensions of the layer planes are small and the separation between the layer planes becomes large, the carbon is referred to as amorphous carbon (for example, charcoal, coke, and soot). Because of their difference in structures, diamond is an electrical insulator, whereas graphite is a good electrical conductor. The high conductivity of graphite and its good chemical stability are attractive features for its use in electrochemistry.
Read More :- http://electrochem.cwru.edu/ed/encycl/art-c01-carbon.htm
Read More :- http://electrochem.cwru.edu/ed/encycl/art-c01-carbon.htm
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