एन्टिबायोटिक

गि्रक भाषामा एन्टी भनेको विपरीत र बायोस् भनेको जीवन हो । अर्को शब्दमा भन्ने हो भने एन्टिबायोटिक भनेको जीवनाशक वस्तु हो र यसले जीवाणुलाई नाश गरेर मानिसलाई रोगबाट छुटकारा दिलाउँछ । जीवाणु नाश गर्ने एन्टिबायोटिकलाई ब्याक्टेरियल साइडल र फैलिन नदिनेलाई ब्याक्टेरियो स्टाटिक भनिन्छ । सन् १९२८ मा एलेक्जेन्डर फ्लेमिङले फंगसबाट पेनिसिलिन निकालेका हुन् । फ्लेमिङ फ्लोरी र चेनले उक्त उपलब्धिका लागि संयुक्त रूपमा सन् १९४५ मा नोबेल पुरस्कार पाएका थिए । हिजोआज विभिन्न किसिमका एन्टिबायोटिक बजारमा उपलब्ध छन् । धेरै चिकित्सकले चलाउने एमोक्सिलिन सन् १९९८ मा मात्र उपलब्ध भएको हो ।

Om!

Om bhur bhuvah svah
tat savitur varenyam
bhargo devasya dhimahi
dhiyo yonah prachodayat
Translation:

"We meditate on the transcendental Glory of the Deity Supreme, who is inside the heart of the earth, inside the life of the sky and inside the soul of Heaven. May He stimulate and illuminate our minds."

 Lets belive in PEACE PEACE & PEACE

 Don't take tension to earn money just do belive in HARDWORK.

Thankyou.

Everybody in earth are under the effect of solar system and the whole condition of universe.

 

My Father and mother.

My birth place

PEOPLE SHOULD BE FREE NOT BOUNDED AS ELECTRON.

The Transistor in a Century of Electronics

A Three Terminal Device

The transistor is a three terminal, solid state electronic device. In a three terminal device we can control electric current or voltage between two of the terminals by applying an electric current or voltage to the third terminal. This three terminal character of the transistor is what allows us to make an amplifier for electrical signals, like the one in our radio. With the three-terminal transistor we can also make an electric switch, which can be controlled by another electrical switch. By cascading these switches (switches that control switches that control switches, etc.) we can build up very complicated logic circuits. These logic circuits can be built very compact on a silicon chip with 1,000,000 transistors per square centimeter. We can turn them on and off very rapidly by switching every 0.000000001 seconds. Such logic chips are at the heart of your personal computer and many other gadgets you use today.

Light Bulbs and Vacuum Tubes

The transistor was not the first three terminal device. The vacuum tube triode preceded the transistor by nearly 50 years. Vacuum tubes played an important role in the emergence of home electronics and in the scientific discoveries and technical innovations which are the foundation for our modern electronic technology. Thomas Edison's light bulb was one of the first uses of vacuum tubes for electrical applications. Soon after the discovery of the light bulb, a third electrode was placed in the vacuum tube to investigate the effect that this electrode would have on "cathode rays," which were observed around the filament of the light bulb. Joseph John Thomson developed a vacuum tube to carefully investigate the nature of cathode rays, which resulted in his discovery, published in 1897. He showed that the cathode rays were really made up of particles, or "corpuscles" as Thomson called them, that were contained in all material. Thomson had discovered the electron, for which he received the Nobel Prize in Physics 1906.

Lee De Forest and The Radio

At the same time as physicists were trying to understand what cathode rays were, engineers were trying to apply them to make electronic devices. In 1906, an American inventor and physicists, Lee De Forest, made the vacuum tube triode, or audion as he called it. The triode was a three terminal device that allowed him to make an amplifier for audio signals, making AM radio possible. Radio revolutionized the way in which information and entertainment reached the great majority of people. The vacuum tube triode also helped push the development of computers forward a great deal. Electronic tubes were used in several different computer designs in the late 1940's and early 1950's. But the limits of these tubes were soon reached. As the electric circuits became more complicated, one needed more and more triodes. Engineers packed several triodes into one vacuum tube (that is why the tube has so many legs) to make the tube circuits more efficient.

Early Computers

The vacuum tubes tended to leak, and the metal that emitted electrons in the vacuum tubes burned out. The tubes also required so much power that big and complicated circuits were too large and took too much energy to run. In the late 1940's, big computers were built with over 10,000 vacuum tubes and occupied over 93 square meters of space. The problems with vacuum tubes lead scientists and engineers to think of other ways to make three terminal devices. Instead of using electrons in vacuum, scientists began to consider how one might control electrons in solid materials, like metals and semiconductors. Already in the 1920's, scientists understood how to make a two terminal device by making a point contact between a sharp metal tip and a piece of semiconductor crystal. These point-contact diodes were used to rectify signals (change oscillating signals to steady signals), and make simple AM radio receivers (crystal radios). However, it took many years before the three terminal solid state device - the transistor - was discovered.

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