A large explosion finally managed to find its way to Earth after traveling across thousands of years in space. This explosion is known from the XMM-Newton and Integral ESA's Space Observatories, and the astronomers were able to find the star died from a very rare group, namely, the magnetar.
Magnetar Illustration. Credit: NASA, the data burst SGR0501 +4516
Magnetar Illustration. Credit: NASA, the data burst SGR0501 +4516
X-rays from this giant explosion arrived at Earth, August 22, 2008, and triggered the automatic sensor on the International Swidt NASA satellite on. twelve hours later XMM-Newton began to gather in order to study the radiation spectrum of the decay in the magnetar explosion in more detail.
Ended in a burst of 4 hours, and during that time hundreds of small explosion had measured. Nanda Rea of the University of Amsterdam who led the team to investigate this incident states, magnetar is a matter of extreme conditions that can not be produced on Earth.
Magnetar is an object with a very strong kemagnitan in the universe. Magnetic field is in the range of 10 thousand million times stronger than Earth's. If the magnetar magically appeared on the half distance between the Earth-Moon, it is undeniable that at the time magnetna field will remove smeua credit card details that are on earth.
Magnetar that appeared and arrested XMM-Newton is known as SGR 0501 +4516, and is estimated to be at a distance of 15,000 light years. Magnetar is by no dikeal to reveal its existence letupannya own. Explosion or explosion occurred in the setting of the magnetar's magnetic field is unstable so that the magnetar's crust and pushing the material was overflowing out of a volcanic explosion is very exotic. Tanglement between the material and magnetic fields can then modify the existing configuration and release more energy.
Five days after the big bang, Integral detects the presence of X-ray high-energy coming from the blast, in a range that can be seen XMM-Newton. X-ray high-energy is then gilang within 10 days and is expected as a result of changes in the magnetar's magnetic configuration. Magnetar explosion could give as much energy with solar flares, although located far across the galaxy, while the sun was not far from us.
X-ray high berenerdi from SGR 0501 +4516 were observed Integral. Credit: ESA / INTEGRAL / IBIS-SIGRI (Rea et al. 2009)
X-ray high berenerdi from SGR 0501 +4516 were observed Integral. Credit: ESA / INTEGRAL / IBIS-SIGRI (Rea et al. 2009)
How can magnetar formed? Until now, there are two ideas put forward about the formation of magnetar. The idea of the first states, magnetar comes from a very small core is left when a star dies magnetk. But the star with a big kemagnitan is extremely rare. There are only a few in our galaxy. Other ideas expressed, throughout the process of a normal star's death, a small part of the core will accelerate and strengthen the dynamo makes medang magnernya and then turned into a magnetar.
We have more astronomers believe that the first idea, but still no real evidence belumm can strengthen these allegations. If there magnetar in galaxy clusters kemagitan stars with large, then the evidence could be obtained.
Until now, only 15 are known to exist magnetar in our galaxy. SGR 0501 +4516 is the first type of "soft gamma repeaters", one of the magnetar type 2 was found after a search for a decade.
Searching was continued with waiting for the next big explosion. And for SGR 0501 +4516, the research team will examine it again next year with the XMM-Newton in the hope of seeing the object in a calmer situation is not in the condition of the explosion, so the research can be done to calm conditions after the storm hit.
Kamis, 19 November 2009
Sabtu, 07 November 2009
Making Own Solar Cell? Part 1: Processing of Silicon
There are a few questions from the many visitors who unfortunately have not had time to author a response. Many ways and forms of the question, but the core is all mawon sami. The first question related to the possibility of making or assembling their own solar cells or independently. While the second question is about the use of raw materials for solar cells made more specifically for the type of silicon solar cells which currently rule the solar cell market. Well, this article will explore two questions little by way of merging the two questions above in two separate articles; can we make solar cells made from independently with natural materials around?
The author believed the sweet promises and wonderful dreams teklnologi offered by solar cells to provide electricity in the long term have been invited even thinking intention to develop their own solar cells in the homeland. Physical form of solar cells that look very simple, easy to install and fairly easy to carry, easy to invite the assumption solar cells. Then, after knowing that the basic material of silicon solar cells authentic type of sand or soil is silica which many have encountered in our homeland, growing more common assumption that the solar cells is likely be developed in a clear ground water will be enough business aroma stung in the future.
A fellow visitors of this blog to write a question like the one below. Authors take this question as a sample of some previous similar questions and preparing this article the author to explain what and how the processing of silicon from silica sand, as well as deciding whether the production of silicon for solar cells we can do or not.
Eric said:
September 12, 2008 at 5:16 pm
Salam kenal Pak Adhi ..
I am interested to produce mono or poly crystalline silica krital. considering in this country there are lots of silica sand but still not optimally use. My question is, whether to convert from natural silica to poly / mono-crystal requires complicated processes? And what kira2 requisite investment costs ..
Thank you ..
There are a lot of silicon in the earth. He is the second largest element in the Earth's crust after oxygen. There are in nature in the form of silica sand or quartz degan also known by the chemical formula SiO2. Land where we pijak also contains silicon. For example, in Indonesia penamnangan silica sand was carried out in Central Kalimantan and Central Java. On the south coast of Java is also believed to have the silica sand deposits. Silicon used for semiconductors and solar cells taken from the separation of Si and O. Currently, the largest silicon producer in the world is China, America, Brazil, Norway and France. Silica resource reserves and the availability of electricity is large enough to be the reason why the countries in the lead in producing silicon.
It takes great power.
The first stage begins with the manufacture of silicon silicon separating the road from the SiO2. The separation is done in a furnace (furnace) is supplied with high-powered electricity. Scheme for the separation of silicon furnaces can be seen below.
Figure 1. Scheme of separation / manufacture of silicon from silica sand. Adapted from here.
Silica sand and carbon (C) simultaneously (picture at left) is inserted into the furnace is equipped with electrodes where the electric current flowing in (middle picture). Silicon separated by silica sand reacting with carbon at high temperatures, ie above 1900 up to 2100 degrees Celsius. This is considering both sand and carbon are two solids in which the reaction takes place only when they melt / melt / melt, coupled with melting point of silica sand over 1800 degrees Celsius. (The chemical reaction is not included).
The high temperature separation process of silicon from silica sand with high consequences of absolute power consumption is used. Why must the electricity and not by burning? Any combustion will not be able to reach the required temperature process for treating silica sand with carbon, so the only way a large flow of electricity aurs is an ideal process temperature can be achieved.
Recorded about 10 to 30 MW (megawatts) of electricity needed in this process depends on how much the furnace is used. Not surprisingly, the only countries which have abundant resources and electricity comes from nuclear power plants or other who may be economically separate the silicon from silica sand because electricity is needed in this process is very large; approximately one-tenth of the electricity produced by the Muara Karang power plant (300 MW) out just for this process.
Figure 2. Muara Karang power plant. One-tenth of its capacity of 300 MW is needed to separate the silicon from silica sand.
Silicon resulting from the separation of Si and O in the silica sand should be purified back to achieve purity silicon levels above 99%. There are two stages to purify the silicon result silica sand separation. The first stage, silicon still has a separation of "impurity" in the form of iron (Fe), aluminum (Al), calcium (Ca) and titanium (Ti) and carbon (C) to be issued. Done at this stage purification process just after the molten silicon out of the furnace (Fig. left center). This process involves the oxidative gas is conducted at a temperature of 1700 degrees Celsius. Large electric power is still needed in this phase. Until this stage, the resulting silicon is called the Metallurgical grade silicon with impurity levels in units of parts per million (ppm, parts per million) are true enough to be used for many purposes.
The next stage, is the preparation and purification of the raw material silicon for solar cells and semiconductor or semiconductor-called grade silicon. This stage is done in other places apart from the separation process of silicon. For information, silicon for semiconductors require purity levels are very high that different from Metallurgical grade silicon. In the world of semiconductors, known as the "nine-eleven" or 11 number 9 which states the level of purity silicon in percent; 99.999999999%. Silicon for the semiconductor must have an element of impurity in units of parts per billion (ppb, parts per billion) or parts per setrilyun (ppt, parts per trillion). Quite simply, if the silicon purity levels below the nominal value, can be guaranteed that a computer processor or memory or solar cells can not walk very well.
Purification of silicon for solar cells and other semiconductors made in the form of gas through a process called the Siemens process. Silicon from the first purification step (Metallurgical grade silicon) reacted with hydrochloric acid gas (HCl) to make silicon chloride gas. This reaction process carried out at a temperature of 350 degrees Celsius.
Silicon chloride and then inserted into the reactor Siemens (picture below), together with hydrogen gas. In the Siemens reactor are the bait rod silicon (silicon feed rod) inverted U-shaped heated at a temperature of 1100 degrees Celsius and cooling. Silicon chloride having a decomposition reaction or a decomposition reaction on the surface of a silicon-silicon bait rod, and silicon results are attached to and unraveling terendap in these bars. The longer the process, the more silicon that settles that enlarges into silicon with a purity level of 11 number 9 on the (chemical reaction is not included).
Figure 3. Schematic diagram of the process and the Siemens reactor for purifying silicon. Adapted from here.
To this end, silicon has a purity that can be used for the purposes of solar cells.
Silicon for solar cells
Solar cells made from silicon in the form of a flat square with a size of 5 x 5 cm or 10 x 10 cm square. The thickness of silicon is about 2 mm. Flat square slab called a silicon wafer for solar cells. Form of silicon wafer solar cells is different from silicon wafers to other semiconductor (chip, computer processor, RAM memory) is a flat round despite having the same thickness (see figure below).
Figure 4. Silicon wafers for electronics (round and flat) and solar cells (blue squares).
This silicon wafer is made through the silicon wafer manufacturing process using high purity silicon-yield previously (semiconductor grade silicon). In summary, the authors describe several ways to make silicon wafers for solar cells.
1. Monokristal type silicon wafer.
Mono crystalline silicon here means it is composed of a single crystal only. While other types of silicon wafers are polycrystals consisting of many krstal. Monokristal silicon wafer is made through a process of Czochralski (CZ) which is the heart of the silicon wafer manufacturing process for semiconductors as well. The process involves the fusion semiconductor grade silicon, followed by income bait rod in the molten silicon into silicon. When the bait rod is withdrawn slowly from the molten silicon, it will automatically be molten silicon from the trunk mennempel bait and frozen as a single large crystal silicon. Temperatures ranged from the 1000-1200 degrees Celsius, the temperature at which silicon can be melted / melting / melted. Silicon which had been frozen was eventually cut into pieces to produce wafers with a thickness of about 2 millimeters.
Figure 5. Scheme Cz process to make silicon wafers. (Top) reactor where the wafer manufacturing slikon, (Middle top) state tengat silicon rod pulled by the feeder. Note the color of the fluorescent signal silicon is still in a state of semi-liquid / melt. (Middle bottom) Room silicon wafer manufacturing plant that is always maintained clean and uniform workers who always used. (Bottom) The resulting silicon wafer (diameter 20-40 cm in length can reach 1-2 m). Adapted from here and here and here.
Figure 6. Solar cells using silicon base material monokristal. Consider a homogeneous blue color on the solar cells.
2. Polycrystals type silicon wafer.
Monokristal silicon wafer is relatively far more difficult and more expensive. Monokristal silicon is used for base material in semiconductor microchip, processor, transistor, memory and so on. State monokristal (containing only one single crystal) makes silicon monokristal almost flawless and very good levels of electricity and heat conductivity. Solar cells will work very well with a high level of efficiency when using this type of silicon.
However, keep in mind that the big issue is how the solar cells to reduce prices still far from the reach of the community. Use clear silicone will monokristal price melonjakkan solar cells that eventually it kontraprduktif. Industry and research community solar cells eventually turn into another type of silicon that is cheaper, easier to make, though somewhat less sacrificing efficiency levels. Currently, both the silicon and polycrystals monokristal same as used by the public.
The author believed the sweet promises and wonderful dreams teklnologi offered by solar cells to provide electricity in the long term have been invited even thinking intention to develop their own solar cells in the homeland. Physical form of solar cells that look very simple, easy to install and fairly easy to carry, easy to invite the assumption solar cells. Then, after knowing that the basic material of silicon solar cells authentic type of sand or soil is silica which many have encountered in our homeland, growing more common assumption that the solar cells is likely be developed in a clear ground water will be enough business aroma stung in the future.
A fellow visitors of this blog to write a question like the one below. Authors take this question as a sample of some previous similar questions and preparing this article the author to explain what and how the processing of silicon from silica sand, as well as deciding whether the production of silicon for solar cells we can do or not.
Eric said:
September 12, 2008 at 5:16 pm
Salam kenal Pak Adhi ..
I am interested to produce mono or poly crystalline silica krital. considering in this country there are lots of silica sand but still not optimally use. My question is, whether to convert from natural silica to poly / mono-crystal requires complicated processes? And what kira2 requisite investment costs ..
Thank you ..
There are a lot of silicon in the earth. He is the second largest element in the Earth's crust after oxygen. There are in nature in the form of silica sand or quartz degan also known by the chemical formula SiO2. Land where we pijak also contains silicon. For example, in Indonesia penamnangan silica sand was carried out in Central Kalimantan and Central Java. On the south coast of Java is also believed to have the silica sand deposits. Silicon used for semiconductors and solar cells taken from the separation of Si and O. Currently, the largest silicon producer in the world is China, America, Brazil, Norway and France. Silica resource reserves and the availability of electricity is large enough to be the reason why the countries in the lead in producing silicon.
It takes great power.
The first stage begins with the manufacture of silicon silicon separating the road from the SiO2. The separation is done in a furnace (furnace) is supplied with high-powered electricity. Scheme for the separation of silicon furnaces can be seen below.
Figure 1. Scheme of separation / manufacture of silicon from silica sand. Adapted from here.
Silica sand and carbon (C) simultaneously (picture at left) is inserted into the furnace is equipped with electrodes where the electric current flowing in (middle picture). Silicon separated by silica sand reacting with carbon at high temperatures, ie above 1900 up to 2100 degrees Celsius. This is considering both sand and carbon are two solids in which the reaction takes place only when they melt / melt / melt, coupled with melting point of silica sand over 1800 degrees Celsius. (The chemical reaction is not included).
The high temperature separation process of silicon from silica sand with high consequences of absolute power consumption is used. Why must the electricity and not by burning? Any combustion will not be able to reach the required temperature process for treating silica sand with carbon, so the only way a large flow of electricity aurs is an ideal process temperature can be achieved.
Recorded about 10 to 30 MW (megawatts) of electricity needed in this process depends on how much the furnace is used. Not surprisingly, the only countries which have abundant resources and electricity comes from nuclear power plants or other who may be economically separate the silicon from silica sand because electricity is needed in this process is very large; approximately one-tenth of the electricity produced by the Muara Karang power plant (300 MW) out just for this process.
Figure 2. Muara Karang power plant. One-tenth of its capacity of 300 MW is needed to separate the silicon from silica sand.
Silicon resulting from the separation of Si and O in the silica sand should be purified back to achieve purity silicon levels above 99%. There are two stages to purify the silicon result silica sand separation. The first stage, silicon still has a separation of "impurity" in the form of iron (Fe), aluminum (Al), calcium (Ca) and titanium (Ti) and carbon (C) to be issued. Done at this stage purification process just after the molten silicon out of the furnace (Fig. left center). This process involves the oxidative gas is conducted at a temperature of 1700 degrees Celsius. Large electric power is still needed in this phase. Until this stage, the resulting silicon is called the Metallurgical grade silicon with impurity levels in units of parts per million (ppm, parts per million) are true enough to be used for many purposes.
The next stage, is the preparation and purification of the raw material silicon for solar cells and semiconductor or semiconductor-called grade silicon. This stage is done in other places apart from the separation process of silicon. For information, silicon for semiconductors require purity levels are very high that different from Metallurgical grade silicon. In the world of semiconductors, known as the "nine-eleven" or 11 number 9 which states the level of purity silicon in percent; 99.999999999%. Silicon for the semiconductor must have an element of impurity in units of parts per billion (ppb, parts per billion) or parts per setrilyun (ppt, parts per trillion). Quite simply, if the silicon purity levels below the nominal value, can be guaranteed that a computer processor or memory or solar cells can not walk very well.
Purification of silicon for solar cells and other semiconductors made in the form of gas through a process called the Siemens process. Silicon from the first purification step (Metallurgical grade silicon) reacted with hydrochloric acid gas (HCl) to make silicon chloride gas. This reaction process carried out at a temperature of 350 degrees Celsius.
Silicon chloride and then inserted into the reactor Siemens (picture below), together with hydrogen gas. In the Siemens reactor are the bait rod silicon (silicon feed rod) inverted U-shaped heated at a temperature of 1100 degrees Celsius and cooling. Silicon chloride having a decomposition reaction or a decomposition reaction on the surface of a silicon-silicon bait rod, and silicon results are attached to and unraveling terendap in these bars. The longer the process, the more silicon that settles that enlarges into silicon with a purity level of 11 number 9 on the (chemical reaction is not included).
Figure 3. Schematic diagram of the process and the Siemens reactor for purifying silicon. Adapted from here.
To this end, silicon has a purity that can be used for the purposes of solar cells.
Silicon for solar cells
Solar cells made from silicon in the form of a flat square with a size of 5 x 5 cm or 10 x 10 cm square. The thickness of silicon is about 2 mm. Flat square slab called a silicon wafer for solar cells. Form of silicon wafer solar cells is different from silicon wafers to other semiconductor (chip, computer processor, RAM memory) is a flat round despite having the same thickness (see figure below).
Figure 4. Silicon wafers for electronics (round and flat) and solar cells (blue squares).
This silicon wafer is made through the silicon wafer manufacturing process using high purity silicon-yield previously (semiconductor grade silicon). In summary, the authors describe several ways to make silicon wafers for solar cells.
1. Monokristal type silicon wafer.
Mono crystalline silicon here means it is composed of a single crystal only. While other types of silicon wafers are polycrystals consisting of many krstal. Monokristal silicon wafer is made through a process of Czochralski (CZ) which is the heart of the silicon wafer manufacturing process for semiconductors as well. The process involves the fusion semiconductor grade silicon, followed by income bait rod in the molten silicon into silicon. When the bait rod is withdrawn slowly from the molten silicon, it will automatically be molten silicon from the trunk mennempel bait and frozen as a single large crystal silicon. Temperatures ranged from the 1000-1200 degrees Celsius, the temperature at which silicon can be melted / melting / melted. Silicon which had been frozen was eventually cut into pieces to produce wafers with a thickness of about 2 millimeters.
Figure 5. Scheme Cz process to make silicon wafers. (Top) reactor where the wafer manufacturing slikon, (Middle top) state tengat silicon rod pulled by the feeder. Note the color of the fluorescent signal silicon is still in a state of semi-liquid / melt. (Middle bottom) Room silicon wafer manufacturing plant that is always maintained clean and uniform workers who always used. (Bottom) The resulting silicon wafer (diameter 20-40 cm in length can reach 1-2 m). Adapted from here and here and here.
Figure 6. Solar cells using silicon base material monokristal. Consider a homogeneous blue color on the solar cells.
2. Polycrystals type silicon wafer.
Monokristal silicon wafer is relatively far more difficult and more expensive. Monokristal silicon is used for base material in semiconductor microchip, processor, transistor, memory and so on. State monokristal (containing only one single crystal) makes silicon monokristal almost flawless and very good levels of electricity and heat conductivity. Solar cells will work very well with a high level of efficiency when using this type of silicon.
However, keep in mind that the big issue is how the solar cells to reduce prices still far from the reach of the community. Use clear silicone will monokristal price melonjakkan solar cells that eventually it kontraprduktif. Industry and research community solar cells eventually turn into another type of silicon that is cheaper, easier to make, though somewhat less sacrificing efficiency levels. Currently, both the silicon and polycrystals monokristal same as used by the public.
Jumat, 23 Oktober 2009
Biological weapons and biotechnology
[Science News, 1/8/2002; By Arief B. Witarto] [Download PDF 50 KB] It was still warm in our ears, the case of bioterrorism in the United States as a continuation of the attacks' terror 11 November "to the two twin towers of the World Trade Center in New York. It is a bioterrorism mode by sending a letter filled with bacterial spores of Bacillus anthracis. Cases in the United States had been eating some of the victims died. Followed by a similar threat in Europe and Japan, although to be "merely" idle action, bioterrorism in this mode can elicit fear in a letter that has become the most common medium of communication in society. This paper is intended to provide information about biological weapons (biological weapons / bioweapon) and the prohibition of business use. Biological weapons and biotechnology
Biological weapons are often referred to as "poor man's nuclear weapon" (Gould, 1997). Cost and technology needed to make biological weapons are much lower and easier than nuclear or chemical weapons. However, the effect of mass destruction was no less powerful than the two weapons had been. According to the calculations of the Office of Technology Assessment in the U.S. Congress in 1993, 100 kg of Bacillus anthracis spores were spread on the capital of Washington could lead to casualties 3 million people. In fact, a similar spread of bacteria from biological weapons installations in the city of Yekaterinburg Russia on 2-3 April 1979 have claimed the victims were killed "tens of thousands of lives' in the surrounding area reported the Union for Chemical Safety, although the official government reports only 66 people (Graeves , 1999). In contrast to nuclear weapons, biological weapons have many types. Although chemical weapons also have many types (such as sarin gas, VX gas, cyanide and so on), because of biological weapons use biological agents such as viruses and bacteria, the numbers tend to increase with the emergence of various new fatal infectious diseases such as Ebola virus, Lassa virus and other on. However, the true agents have been used as a biological weapon is a bacterium that has long been known to man, readily available in nature and is not difficult to handle. Bacillus anthracis, the cause of anthrax disease is the primary option and has proven to be used in the incident in America recently and tried to made in Russia and Iraq. In addition, the deadly bacteria, and recorded as a biological weapon agent is Yersinia pestis causes plague, a poison Clostridium botulinium causes botulism, Francisella tularensis (tularaemia), and others. On the other hand, because the pathogen bacteria was long known, the treatment was known to many antibiotics and its prevention can be done with vaccination. What is more frightening is the agent of biological weapons that have been engineered in biotechnology so that antibiotic resistant, more virulent, stable in storage and so on. The easiest is engineered for resistance to antibiotics. Such properties are usually only caused by a simple collection of genes or even a single gene, so easily moved from one type of bacteria to other bacteria. This technology also has become standard in every molecular biology experiment. Bacillus anthracis can be killed with antibiotics penicillin types can easily be made resistant to gene transfer -lactamase enzymes. Biopreparat, making installation of a network of biological weapons in Russia, reportedly had fake plague-causing bacteria with resistance to 16 kinds of antibiotics. Other engineering methods that enable a technology called "directed evolution" (directed evolution). This method was first developed in 1994 by Dr. Willem Stemmer researchers at biotechnology company, Maxygen, based in Redwood City, California. Method based on the exchange of DNA fragments at random, or referred to as DNA shuffling, was first applied to a single gene coding for a protein. But then expanded to a larger level, which is a collection of genes to the genome. Stemmer and current vice president of the company has managed to engineer the bacterium Escherichia coli that has a resistance to antibiotics Cefotaxime, 32 thousand times higher. Current knowledge of the complete genome sequences of pathogens such as bacteria cause tuberculosis, cholera, leprosy etc., will make it easier for engineering bacteria with a power greater suicide, using this method. Although the two stories above the new limited scenarios, but it is no longer a dream. The research team from the CSIRO, Australia led by Dr. Ronald J. Jackson, published in the Journal of Virology in February 2001 issue, gives a clear picture. The research team was to genetically engineered mousepox virus to control the fertility of rats. The virus is not so dangerous, but when both genes are also mensisipkan protein interleukin-4, mousepox became so deadly. Though the goal is to improve the efficiency of viral lower fertility by extending the production of mouse antibodies to the egg cell itself. The result was sensational allegations outside the scientific community because of mousepox virus is a close relative of smallpox virus causes smallpox. Can imagine this technology is likely to apply to the smallpox virus which ranked first in the kebahayaannya level as a biological weapon. Prohibiting biological weapons Agreement on the international level which prohibit the use of biological weapons began in the Geneva Protocol of 1925. However, history shows that the development of biological weapons continues. One of the documented examples are the use of biological weapons by Japanese troops in World War 2 in China. For that, the treaty agreed in 1972 Biological and Toxin Weapons Convention (BTWC) which was sponsored by the United Nations. In this agreement, more emphasized again about "banning the development, manufacture and storage of all types of biological weapons". Until now no fewer than 140 countries have signed this agreement, including Indonesia, America, and Russia. However, the main weaknesses of the BTWC is no collective agreement for monitoring and verification, so the agreement is similar to "lion with no teeth". Russia and Iraq proved to develop biological weapons despite signing the agreement. This led to the establishment of an ad hoc group in 1995 to create inspection and verification protocols in the field. In the beginning, America fully supports the Ad Hoc committee work through President Clinton's statement in 1998. However, at the end of the protocol is almost complete, the American attitude of government under President Bush turned to the total with not only rejected the protocol, but also threatened to walk out of the agreement. This attitude is reminiscent of the American step out of the Kyoto treaty on reducing emissions of carbon dioxide gas or agreements intercontinental missiles. The main reasons put forward by the United States in July 2001 and is a favorite of the lack of routine inspections or sudden to all military installations, academic and industry-related weapons, which may cause leaking of trade secrets. In addition, Americans have worried protocol, can be dangerous arms trade and related technology. As reported the journal Nature Biotechnology, until now the U.S. is the lawyer-related technology exports, the largest in the world. In 1994 alone, there are 531 licenses sold to foreign countries. The rejection policy is strongly supported by the U.S. pharmaceutical industry association (PHRMA). On the other hand, America was strengthening in domestic preparedness against biological weapons attacks. Disclosure of secret program Russia and Iraq as well as manufacturing and distribution of the bacteria Bacillus anthracis by deviant sect Aum Shinrikyo in Japan, in 1995, have triggered it. In 1999, the U.S. Congress has allocated 111 million dollars for the Centers for Disease Control and Prevention (CDC) to strengthen the system of early detection and treatment of the dangers of biological weapons (Khan, 2000). Associated with it in April 2000, CDC has issued recommendations for the strategic measures against biological weapons attacks by forming a network of laboratories across the country. Not only at the level of civilians, Americans also have prepared themselves to military strength. For example with the anthrax vaccine to all military personnel (Fidler, 1999). In the end, which was originally BTWC validation will be performed at the 5th Review Conference meeting in Geneva, Switzerland on 19 November to 7 December 2001 that then, fail. According to the President of the Conference, Tibor Toth of Hungary, is already 98% the way to the signing of the BTWC through smoothly. Many parties, the American rejection rate is the main cause of this failure. In the end it was decided to setahuan again backed the deal. Conclusion Pharmaceutical and biotechnology industries Americans, need to reconsider its rejection of this protocol. Actually, if there is goodwill, there is no difficulty to find the middle ground. For example, the chemical industry has proven to be arranged between the interests of inspection rules trade secrets that treaty banning chemical weapons, Chemical Weapons Convention (1993) to function properly. In the United States own country, the voices against the government refusal enough especially among scientists, for example from Dr. Barbara Rosenberg, chairman of the Federation of American Scientists' Working Group on Biological Weapons. Even the government's adviser for chemical and biological weapons, Professor Matthew Meselson of Harvard University warned that America's unilateral refusal to be captured as an attempt "hiding something" (the journal Nature, July 2001). We all hope that recent events are reminded again to the dangers of biological weapons. [*]
Nanotechnology
nanotechnology is now increasingly rapid development. Nanometer itself means one by one billion meters, so this technology is also related to the creation of small objects. Incorporated therein physics, engineering, molecular biology, and chemistry.
Albert Einstein himself, as part of his doctoral dissertation, to calculate the size of a sugar molecule from experimental data. The result of each molecule is about one nanometer. Nearly a hundred years later, nanometers has become the agenda of many researchers.
But, actually, not all this nanotechnology really nano. There is a real deal micron size structures, or one by one million meters, a thousandth, and greater than other nano. Nano technology in most cases is not really technology. But, more basic research in the form of various structures with dimensions of one to hundreds of nanometers.
Another confusion, a number of nano technology is there all the time. For example, black carbon particles nano size was used as an additional sticker tires since a hundred years ago. Vaccines are often comprised of one or more protein-dimensional nano-scale can also be included in these technologies.
Nature has a lot to create nano structures. But, a more stringent definition may be submitted as Mihail C Rocco from the National Science Foundation (NSF) in the United States. According to the site Sciam.com Mihail, nano technology has several important elements; dimensions between one and 100 nanometers, designed through a process of chemical controls and physics, and can be combined to form larger structures.
And, according to the definition of technology was really there. For example combining several nonmagnetic layers, each layer thickness of less than one nanometer, can produce sensors for disk drives are more sensitive. Since the introduction in 1975, these magnetic products have become the growth drivers of the data storage industry.
Increasingly small electronic chip size is also a factor that fosters interest in nano technology. Computer companies that have a large laboratory, such as IBM and Hewlett-Packard, incorporating a nano in its activities. As the conventional silicon electronic equipment is not used anymore, maybe ten or 25 years, electronic equipment likely will replace nano technology.
Outside of biology and electronics, nano particles are used to improve the quality of everyday products. For example a company called Nanophase Technologies has made the particles of zinc oxide for sun screen products (sunscreen), so the cream is usually white became transparent.
Technological dreams
U.S. government itself has its own agenda for nano technology. They wanted to create nano size material that can reduce the size, weight, and power source requirements of the shuttle, making environmentally friendly manufacturing processes, and form the basis for biodegradable pesticides.
Every study has his own risk. But nanotechnology has problems of its own. Desire happen as a respectable science rules often mixed with an association of the futurists who see the nano as a way to techno-utopian, such as the industrial world without pollution, wealth without limit, even the desire to reach eternal life.
In 1986 for example, appears the book Engines of Creation by Eric Drexler K is quite popular. This book describes a number of nano machines that can produce virtually all types of goods, and eliminate the problem of global warming, cure disease and prolong life dramatically.
For the nonilmuwan, Drexler fantasy of nanotechnology is seen as a bridge connecting the world of science and fiction. Scientists who always wanted to find a solution would also be interested in talking about delaying the product of age or food grower machine.
Indirectly, Drexler's work may also be a really interesting person into the scientific world. As a subgenre of science fiction books, works of Drexler technologies like Star Trek movies that promote interest in the youth space that will eventually pursue a career in astrophysics or aeronautics.
Among chemists and scientists who is now a nanotechnology expert, predicted Drexler has its own charm. Because until now not been able to create machines that such nanoskopik able to help revive the brain that have been frozen.
Zyvex, a company that is interested in nano technology Drexlerian style, have experienced how difficult it is to create nanometer-sized robots. Thus, the company is now more satisfied handle elements greater micromechanics.
Outside of this issue, nano technology world is still struggling to unify the view. Some research will continue to run whatever it is. IBM will continue to build such magnetoresistive product regardless of whether research is nanotechnology or not.
Example of this concept can be incorporated nano, the technology can be the basis for the new industrial revolution. To be successful, the technology does not only need to throw away the dream of generating nano robot's body, but also eliminates the excessive rhetoric. More importantly, the basic nano science must move to identify the type of nanotechnology should be realized.
solar cells
History of solar cells
The term "photovoltaic" comes from the Greek φῶς (phōs) meaning "light", and "voltaic", meaning electric, from the name of the Italian physicist Volta, after whom a unit of electrical potential, the volt, is named. The term "photo-voltaic" has been in use in English since 1849.[1]
The photovoltaic effect was first recognized in 1839 by French physicist A. E. Becquerel. However, it was not until 1883 that the first solar cell was built, by Charles Fritts, who coated the semiconductor selenium with an extremely thin layer of gold to form the junctions. The device was only around 1% efficient. Sven Ason Berglund had a number of patents concerning methods of increasing the capacity of these cells. Russell Ohl patented the modern junction semiconductor solar cell in 1946[2], which was discovered while working on the series of advances that would lead to the transistor.
The modern age of solar power technology arrived in 1954 when Bell Laboratories, experimenting with semiconductors, accidentally found that silicon doped with certain impurities was very sensitive to light. Daryl Chapin, with Bell Labs colleagues Calvin Fuller and Gerald Pearson, invented the first practical device for converting sunlight into useful electrical power.[3] This resulted in the production of the first practical solar cells with a sunlight energy conversion efficiency of around 6%.The solar battery was first demonstrated on April 25, 1954. The first spacecraft to use solar panels was the US satellite Vanguard 1, launched in March 1958 with solar cells made by Hoffman Electronics. This milestone created interest in producing and launching a geostationary communications satellite, in which solar energy would provide a viable power supply. This was a crucial development which stimulated funding from several governments into research for improved solar cells.
In 1970 the first highly effective GaAs heterostructure solar cells were created by Zhores Alferov and his team in the USSR.[4][5] Metal Organic Chemical Vapor Deposition (MOCVD, or OMCVD) production equipment was not developed until the early 1980s, limiting the ability of companies to manufacture the GaAs solar cell. In the United States, the first 17% efficient air mass zero (AM0) single-junction GaAs solar cells were manufactured in production quantities in 1988 by Applied Solar Energy Corporation (ASEC). The "dual junction" cell was accidentally produced in quantity by ASEC in 1989 as a result of the change from GaAs on GaAs substrates to GaAs on Germanium (Ge) substrates. The accidental doping of Ge with the GaAs buffer layer created higher open circuit voltages, demonstrating the potential of using the Ge substrate as another cell. As GaAs single-junction cells topped 19% AM0 production efficiency in 1993, ASEC developed the first dual junction cells for spacecraft use in the United States, with a starting efficiency of approximately 20%. These cells did not utilize the Ge as a second cell, but used another GaAs-based cell with different doping. Eventually GaAs dual junction cells reached production efficiencies of about 22%. Triple Junction solar cells began with AM0 efficiencies of approximately 24% in 2000, 26% in 2002, 28% in 2005, and in 2007 have evolved to a 30% AM0 production efficiency, currently in qualification.
Recent world record claims of efficiency for multiple junction solar cells are discussed in the Records section.
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