You must have often heard this name Field-effect transistor, electric field people know it by its short-form FET. But do you exactly what it is and for what it is used? I know most of you do not know about it, Although many of you have heard this name many times before, but still you never paid attention to it. So in this article, we will know about Field-effect transistors, what it is, and its usage.
What is Field-effect transistor
The field-effect transistor which is known as FET is an electronic device that uses an electric field to control the flow of current. Like many other transistors, the field-effect transistor has also three terminals which are called ‘source’, ‘drain’, and ‘gate’. FETs control the flow of current by the application of a voltage to the gate and applying a threshold voltage to the gate allows a current to flow from the source to the drain. The field-effect transistor can be used as a switch by increasing and decreasing the gate voltage around its threshold value. By increasing the gate voltage above the threshold, Field Effect Transistor operates as current amplifiers.
There is another name by which field-effect transistor is known, and that is “Unipolar Transistor.” And the reason why it is known as Unipolar Transistor is that they involve a single-carrier-type operation. That is, FETs use holes or electrons as charge carriers in their operation, but not both.
The Beginning Of Field Effect Transistor
It was 1925 when the first time the concept of a field-effect transistor (FET) was first patented and the Austro Hungarian physicist Julius Edgar Lilienfeld is the man who was behind it. Also, there was another man Pakar Heal, who did this in 1934. But unfortunately, both of them were unable to build a working practical semiconducting device based on their concept.
After the 17-year patent expired, in 1947, the transistor was observed and explained by William Schockley’s team at Bell Laboratories. Shockley initially attempted to build a working FET by trying to modulate the conductivity of a semiconductor but was also unsuccessful. The first FET device to be successfully built was the Junction Field-Effect Transistor (JFET) which was first patented in 1945 by Heinrich Welker. In 1950, two Japanese engineers Jun-ichi Nishizawa and Y. Watanabe invented a new type of JEFT, which known as the static induction transistor (SIT). In 1953 two engineers George F. Dacey and Ian M. Ross were built a working practical JFET and the special thing about this invention is that they built it by following Shockley’s theoretical treatment.
Although JFET was a very useful tool, it still had issues, and in the process to repair these issues many other variants of the field-effect transistor were invented. In 1959 there was a major change that came in the field of a field-effect transistor, and that change was the discovery of MOSFET i.e. metal – oxide – semiconductor field-effect transistor. The metal–oxide–semiconductor field-effect transistor (MOSFET) was invented by Mohamed Atalla and Dawon Kahng.
After that in the field of field-effect transistor many other things also invented, such as CMOS (complementary MOS) by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963, the first report of a floating-gate MOSFET by Dawon Kahng and Simon Sze in 1967 and a double-gate MOSFET was first demonstrated in 1984 by Electrotechnical Laboratory researchers Toshihiro Sekigawa and Yutaka Hayashi.
Terminals of Field Effect Transistor
As I mentioned above there are three terminals of field-effect transistor, Source, Drain, and Gate, so let’s take a short instruction of them…
- Source – Source (S), is the terminal through which the carriers enter the channel, and traditionally, current entering the channel at S is designated by IS.
- Drain – Drain (D), is the terminal through which the carriers leave the channel, and traditionally, current entering the channel at D is designated by ID and Drain-to-source voltage is VDS.
- Gate – Gate (G) is the terminal that modulates the channel conductivity and by applying a voltage to G, one can control ID.
Types Of Field Effect transistors
Although I mentioned some type or subtype of Field-effect transistors above but still there are so many others. Field-effect transistors have total 16 types, so here are the names…
The MOSFET (metal-oxide-semiconductor field-effect transistor)
The JFET (junction field-effect transistor)
The MNOS (metal–nitride–oxide–semiconductor transistor)
The FREDFET (fast-reverse or fast-recovery epitaxial diode)
The HIGFET (heterostructure insulated-gate field-effect transistor)
The MODFET (modulation-doped field-effect transistor)
The TFET (tunnel field-effect transistor)
The HEMT (high-electron-mobility transistor)
The ISFET (ion-sensitive field-effect transistor)
The BioFET (Biologically sensitive field-effect transistor)
The MESFET (metal-semiconductor field-effect transistor)
The GNRFET (graphene nanoribbon field-effect transistor)
The VeSFET (vertical-slit field-effect transistor)
The CNTFET (carbon nanotube field-effect transistor)
The OFET (organic field-effect transistor)
The DNAFET (DNA field-effect transistor)
The QFET (quantum field-effect transistor)
The SB-FET (Schottky-barrier field-effect transistor)
So these are the types of field-effect transistors that are more than 20. At present, A MOSFET (metal-oxide-semiconductor field-effect transistor) is the fundamental transistor behind most of the electronics including computers. MOSFET has a metal contact for the gate and it is separated from the bulk transistor (substrate) by an oxide layer, typically SiO2 (silicon dioxide) which makes sure no current flows through the gate.
So that is the basic of field-effect transistor, in future we will learn more about it such as how field-effect transistor works and its advantages and disadvantages. Hopefully, today’s article will prove useful to you but still if you have any questions or concerns about field-effect transistors.
About The World’s First Immortal Human Cell Line
Did you know, which were the world’s first immortal human cell line? I know most of us do not know about it, so HeLa cells are the first immortal human cell line. This cell line developed from a sample of cervical cancer cells which was taken from an African-American woman, Henrietta Lacks, on February 8, 1951. The name of this cell line, HeLa, also came from the name of the same African-American woman Henrietta Lacks, the name was composed by the mixing first two letters of Henrietta Lack’s first and last name. Henrietta Lacks herself did not even know about the removal of this cell line from her cells. After researching these cell lines, In 1953, Theodor Puck and Philip Marcus made a clone of hela, which became the first human cell to be cloned and then freely distributed samples of HeLa to other researchers.
Since the cells’ first mass replications, they have been used by researchers in several types of experiments, including disease research, gene mapping, the effects of toxic substances on organisms and radiation effects on humans. Although the primary use of the Hela cell line was for cancer research but HeLa cells gave many other medical breakthroughs and gave approximately 11,000 patents.
Why HeLa Cell Line Known As Immortal Cell Line?
These were the first human cells that grew up in a laboratory that was naturally “immortal”, which means that they do not die after a certain number of cell division. Usually, human cell culture dies within a few days after a set number of cell divisions, which process is called senescence. This causes a problem for the researchers because experiments with using normal cells can not be repeated on identical cells (clones), nor can the same cells be used for extended study. Cell biologist George Otto Gay took one of the HeLa cells and divide that cell, and found that if the cell was given proper nutrients and appropriate environment then the culture survived indefinitely. The original cells continued to mutate.
Hela cells are able to split frequently, they have an enzyme called telomerase, overactive telomerase rebuilds telomeres after each division, prevents cellular aging and cellular senescence, and allows permanent division of cells. Now, Hela has many strains, all get from the same cell. Along with this, HeLa cells grow easily and abnormally fast; they double cellular count in only 24 hours, making them ideal for large-scale testing. They grow so fast that they can contaminate other cell cultures and overtake them. Although there are other immortal human cells also exist but HeLa cell line is the first among them.
HeLa Cells Use in Research
As I mentioned above, HeLa cells used by researchers in several kinds of experiments such as disease research, gene mapping, the effects of toxic substances on organisms and radiation effects on humans, etc. In all these uses, in my opinion, the most important application of HeLa cells is in the development of the polio vaccine, and that was when polio was becoming one of the biggest deadly diseases. In 1953, a cell culture factory was established to supply salk and other labs along with HeLa cells, And in less than a year, the salak vaccine was prepared for human trials. Hela cells were also used in testing how the Parvovirus infects the cells of humans, dogs, and cats. These cells have also been used to research on viruses such as orophu virus (OROV).
In the year 2011, Hela cells were used in the researches of the novel Hepatamethin Dye IR-808 and other analogs, which are currently available for their unique uses in medical diagnostics, the development of theranostics, the individualized treatment of cancer patients with the aid of PDT, co-administration with other medicine, and irradiation. Also in the year 2014, HeLa cells were shown to be viable cell lines for tumor xenografts in C57BL / 6 naked mice, and later on to investigate the vivo effects of fluoxetine and cisplatin on cervical cancer.
So this everything about the world’s first immortal human cells, HeLa cells. Hopefully, now you may have understood what is HeLa cells and it’s immortality and advantages in researches. Still, if you any questions about the hela cell line or immortal human cell line so you can ask us in the comments section.
How Glass is Made in Factory |Process of Making Glass
Glass, a special kind of metal from which many useful things can be made. We are surrounded by things made of glass, whether it be the glass windows of our house, the windshield of our car, the showcase of our house or our mirror in which we see the reflection of ourselves. Despite having so much available around us, many of us are unaware of how glass is made, and where from it came the very first time. So let’s know everything important about glass and start it by knowing process of making glass…
How Glass is Made
Glass is an amorphous solid. The glass is usually brittle and often optically transparent. Glass is a transparent or opaque material made of inorganic materials, from which many other things are produced. The invention of glass was a huge event for the world and glass has great importance in today’s scientific progress.
Only a very few people know this and you may be also surprised to know that glass is made of sand because the most important material for making glass is silica, which is an integral part of sand.
Silica is found in a free state in nature and is also found as silicate compounds. Silica is most commonly found in quartz form. Now this question will definitely be in your mind that, which type of sand is suitable for making glass, is it the exact sand that we see around us, or any special sand? So the most suitable sand for making glass is one in which the silica content is at least 99 percent and iron as ferric oxide (Fe2O3) is less than 0.1 percent. The sand particles should also be 0.5–0.25 millimeters in diameter. Sand is also washed by water to produce good glass.
To make a glass, the sand and some other material are melted in a furnace at about 1500 degrees Celsius and then after melting perfectly, the molten glass is poured into the grooves, so we can make our desired things. This process looks quite simple, but to make glass you must be proficient in this process.
The most common glass is soda-lime glass which has been used for centuries to make windows and glass glasses etc. The soda-lime glass contains approximately 75% silica (SiO2), sodium oxide (Na2O) and lime (CaO), and many other substances in small quantities.
It is also very important to have some alkaline substances like sodium carbonate for making normal glass. With this mixture, the liquid content is reduced and the fluidization process becomes simple. The glass that is formed by the dissolution of these two substances is known as water glass because it is water-soluble. To make the glass permanent, some type of dibasic oxides such as calcium oxide (lime) or sis oxide also has to be added. Each substance produces certain properties in glass and keeping these properties in mind, mixtures of glass are made.
History Of Glass
Although there is no complete evidence that shows how and when the glass was first discovered but according to some old saying, Humans came to know about glass when some traders placed food vessels on clay slopes on the coastline of Phineasia in Syria. When the fire ignited, they saw a stream of liquefied glass flowing. This glass was formed by the combination of sand and Shore.
Historically, the first method of producing a glass-like glow on utensils was invented in Mesopotamia (Iraq) about 12,000 years before Christ. The earliest glass found in Egypt in the form of molded amulets believed to be 7,000 years before Christ.
With the passage of time, the manufacture of different types of glass in each country progressed with its requirements and scientific advancement. England, France, Germany, and the United States owe a lot of credit for the modern growth of the glass industry.
So hopefully, now you know everything about glass such as how glass is made or the history of glass and the process of making glass in factories but still, if you have any questions in your mind you can ask us in the comments section.
Why does the Moon Actually Change its Shape Everyday?
Every night we see the moon in a new shape, the phases of the moon changes every day, and that we all have watcher and witnessed, so does the moon really change its shape? Can it happen? So what is the reasons, let’s know about it….
Who does not cherish the fine arts of the moon? Where in the sky Sun is always seen in a perfectly spherical shape, but the same moon changes its shape from day to day. This rise and fall of the moon always continues in a sequence. There comes a time when the moon becomes completely lost, which we call the new moon, and when the moon comes in its full form, it is called a full moon. The journey from full moon to new moon takes 15 days. It takes 15 days to reach new moon from a full moon, and again 15 days for the full moon from newmoon. However, if seen completely, there is a difference of about twenty-nine days between one full moon to another full moon. This whole process of changing its shapes known as “phases of moon.”
Before understanding this, it is necessary to know that, like many planets and natural satellite, the moon does not have any light of its own, rather it is the light of the sun falling on it which is reflected to us. When any round object is illuminated, then half of its front is illuminated, but the light does not reach the back part and remains dark there. We can see the same part of the moon which is illuminated. But due to the orbit of the moon, we are not always able to see even that half.
In short, The phase of the moon is how much of the moon appears to us on Earth to be illuminated by the sun.
As I already mentioned, in every 29.53 days the phases of the moon make a complete cycle. As the moon circles the earth, we can only see a portion of the illuminated side of the moon. As the moon orbits or circles the Earth, the phase changes. We’ll start with what is called the New Moon phase. This is where we can’t see any of the lighted side of the moon.
At the beginning of this phase, the moon lies between our Earth and the Sun, and as the Moon revolves around the Earth, we begin to see more and more illuminated sides of the Moon, and this process continues until finally, the Moon does not reach the opposite direction of the earth from sun and we get a full moon. And then as the moon revolves around the Earth, we see less and and less of the lighted side.
So it would not be wrong to say that we have a full moon every night, but we are able to see only the part which has illuminated by sunlight. So it is clear now that the moon does not change its shape, it always remains the same, but it visible in different shapes because of sunlight reflections.
Hopefully, now you may have understood what is the phases of the moon and why moon changes its shape every night. But still, if you have any questions About phases of moon so you can ask us in the comments section.