1.In 1959, the famous physicist and future Nobel Prize winner Richard Feynman gave a lecture to the American Physical Society called "There's Plenty of Room at the Bottom" («Там внизу много места»). His speech was about the field of miniaturization and how he believed man would create increasingly smaller, powerful devices. In 1986, Eric Drexler wrote "Engines of Creation" («Машины созидания») and introduced the term nanotechnology.
2.At the nanoscale, objects are so small that we cannot see them -- even with a light microscope. Nanoscientists have to use tools like scanning tunneling microscopes or atomic force microscopes to observe anything at the nanoscale. Scanning tunneling microscopes use a weak electric current to study the scanned material. Atomic force microscopes scan surfaces with an incredibly fine tip. Both microscopes send data to a computer, which can collect the information and display it graphically on a monitor.
3.What is the difference between graphite and diamonds? Both materials are made of carbon, but both have very different properties. Graphite is soft; diamonds are hard. Graphite conducts electricity, but diamonds are insulators and cannot conduct electricity. Graphite absorbs light; diamonds are usually transparent. Graphite and diamonds have
these properties because of their differences at the nanoscale. They have different crystal structures: the way the carbon atoms are arranged in space is different for carbon and diamonds.
4.Eric Drexler, the man who introduced the word nanotechnology, presented a frightening end-of-the-world picture -- self-replicating (самовоспроизводящиеся) nanorobots getting out of control and rapidly consuming all matter on Earth as they use carbon from the environment to build more of themselves. It is called the "grey goo" («серая слизь») scenario, in which synthetic nano-size devices replace all organic material. According to another scenario, nanodevices made of organic material wipe out the Earth -- the "green goo" scenario.
5.You may be surprised to find out how many products on the market are already based on nanotechnology: sunscreens, self-cleaning glass, clothing, scratch-resistant coatings, antimicrobial bandages,
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swimming-pool cleaners and disinfectants. New products incorporating nanotechnology are coming out every day. Wrinkle-resistant fabrics, deep-penetrating cosmetics, liquid crystal displays (LCD) and other goods using nanotechnology are on the market. Very soon, we'll see dozens of other nanotechnology products ranging from Intel microprocessors to bio-nanobatteries only a few nanometers thick.
UNIT 3
Reading 3-А
Radiation and Radioactivity
"Life on earth has developed with an ever present background of radiation. It is not something new, invented by the wit of man: radiation has always been there."
Eric J. Hall
1.As is the case with so many discoveries, the discovery of the phenomenon of radioactivity was purely accidental. It was discovered in 1896 by the French physicist Henri Becquerel (1852-1908), who was interested at that time in the phenomenon of fluorescence. Не found that compounds of uranium emitted rays that gave an impression on а photographic plate covered with black paper. These rays were able to pass through thin sheets of metal and other substances that are opaque to light. Becquerel called these rays 'radiation'.
2.It is now known that radiation is emitted by the atoms themselves. The radiation may be in the form of particles, such as neutrons, alpha particles, and beta particles, or waves of energy, such as gamma and X- rays. The property of certain atoms to emit radiation is called radioactivity. Such atoms are called radioactive, and the process in which they spontaneously disintegrate or decay emitting both particles and energy is known as radioactive decay. This process occurs because unstable isotopes tend to transform into different, more stable atoms.
3.As unstable isotopes decay and stabilize themselves in this way, a radioactive material becomes less radioactive. Atoms in a radioactive substance decay at a characteristic rate. Each radioactive substance has its own 'half-life'. The half-life is the time taken for half of the atoms of a radioactive substance to decay. Half-lives can range from a millionth of a second to millions of years depending on the element concerned. After one half-life
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the level of radioactivity of a substance is halved, after two half-lives it is reduced to one quarter, after three half-lives to one-eighth, and so on. Take iodine-131, which has a half-life of eight days. If we start off with a billion atoms of I-131, it will be practically all gone within three months. On the other hand, uranium-238 has a half-life of about 4.6 billion years, which is about the lifetime of the earth. Starting with a billion atoms of uranium, it takes 4. 6 billion years for half of them to become stable.
4. This leads to a very important fact about radioactivity. If a substance has a long half-life, it will not give off much radiation in a second - it will have 'low activity’. In general, substances with very long half-lives are not very radioactive. On the other hand, substances with very short half-lives are very radioactive but are soon gone. The most dangerous ones are those in between, such as caesium (half-life 28 years), which are radioactive enough to cause a problem, but have a long enough half-life to remain radioactive for a considerable period of time.
Exercise 1. The following sentences (A-F) summarize the four paragraphs of Reading 3-A. Read the sentences and then match them to the paragraphs of Reading 3-A, 1-4.
A.The radioactivity of a substance depends on its half-life.
B.Radiation and radioactivity are not the same thing.
C.The discovery of radioactivity was purely accidental.
D.Each radioactive isotope has its own characteristic half-life which can range from a millionth of a second to millions of years.
Exercise 2. Match the two parts of the sentences. Look at Reading 3-A to help you.
1.The property of certain atoms to emit radiation...
2.The radiation may be in the form of particles,...
3.The process in which radioactive atoms spontaneously disintegrate or decay...
4.This process occurs because unstable isotopes...
5.The half-life is the time...
6.Substances with very long half-lives are not very radioactive, … A. .... emitting both particles and energy is known as radioactive decay. B. .... tend to transform into different, more stable atoms.
C. .... taken for half of the atoms of a radioactive substance to decay.
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D. .... while substances with very short half-lives are very radioactive but are soon gone.
E. .... such as neutrons, alpha particles, and beta particles, or waves of energy, such as gamma and X-rays.
F. ….is called radioactivity.
Exercise 3. Classify the nouns below according to their suffixes. Copy them out.
Radiation, measurement, fluorescence, emission, impression, ability, passage, property, disintegration, stability, equipment, difference, excitation, tendency, dependence, density, voltage, requirement, existence, brevity, absorption, achievement, deflection, invention, isolation, substance, radioactivity, storage, development, accuracy.
Exercise 4. Use Reading 3-A to find the English equivalents for the following Russian phrases.
Как часто бывает с открытиями; интересоваться явлением; элементы и соединения; соединения урана; оставлять отпечаток на; проходить сквозь тонкие листы; непроницаемый для света; энергия в виде волн; радиоактивный распад; распадаться с характерной скоростью; находиться в диапазоне от… до…; данный элемент; вызывать проблему; оставаться радиоактивным; значительный период времени.
Exercise 5. Read the text again and answer the questions below.
1.When was the phenomenon of radioactivity discovered? Who made this discovery?
2.How was the discovery made?
3.Where does radiation come from?
4.In what form can radiation be emitted?
5.What is radioactivity? What is the difference between radiation and radioactivity?
6.What is meant by radioactive decay?
7.Why does the process of radioactive decay occur?
8.What happens when unstable isotopes decay?
9.What is meant by the half-life of a radioactive substance?
10.What does the half-life of a radioactive substance depend on?
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11.Which is more radioactive: substances with very long half-lives or those with very short half-lives?
12.What radioactive substances are the most dangerous ones?
Reading 3-B
Alpha, Beta and Gamma Rays
Three different types оf radiation are emitted by radioactive substances. These radiations for brevity are called alpha rays, beta rays, and gamma rays.
The alpha rays consist of positively charged particles projected from the parent atom with а velocity about one-tenth the velocity оf light. They are very easily absorbed by thin foil or by a few centimeters of air. They affect а photographic plate, cause many bodies to fluoresce brilliantly, and ionize the air through which they pass. They are deflected by an electric or a magnetic field.
The beta rays consist of negatively charged particles which are projected from the atom of the radioactive substance with a velocity which is nearly, but not quite, as great as the velocity of light. Because of their larger velocities and smaller mass, they are much more penetrating than the alpha particles. They produce much less ionization in the gas through which they pass than do the alpha particles and are less active photographically than alpha particles. In an electric and magnetic field they are deflected just as cathode rays are deflected.
The gamma rays are extremely penetrating, and are not deflected by either а magnetic or an electric field. Their nature is entirely different from that of the alpha or beta rays. They are electromagnetic pulses like very penetrating Х-rays.
Exercise 1. Use Reading 3-B to find the English equivalents for the following Russian phrases.
Поглощать излучение; воздействовать на фотопластинку; исходный атом; вызывать свечение; отклоняться в магнитном поле; из-за высокой скорости; проникающее излучение; ионизировать газ; вызывать ионизацию; электромагнитные импульсы; для краткости.
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