Заглавная страница Избранные статьи Случайная статья Познавательные статьи Новые добавления Обратная связь
Влияние общества на человека
Приготовление дезинфицирующих растворов различной концентрации
Практические работы по географии для 6 класса
Организация работы процедурного кабинета
Обработка изделий медицинского назначения многократного применения
Изменения в неживой природе осенью
Уборка процедурного кабинета
Сольфеджио. Все правила по сольфеджио
Балочные системы. Определение реакций опор и моментов защемления
Medical teams, rescue teams, trapped, rubble, epidemic, casualties, toll, collapse, outbreak, earthquake
In some parts of the world the ground shakes from time to time. This is called an _____ and if it’s a bad one, the number of (dead and injured people) is sometimes large. Buildings often _____ and _____ have to search for people who are _____ under the _____. Sometimes water supplies are affected and there is an _____ of disease, called an _____. _____are sent by the government to help the sick. The death _____ can reach hundreds or even thousands.
Задание 3. Заполните пропуски словами
Healthy, solid particles, quantities, ultraviolet, dump, combustion, wild plants, atmosphere, pollution
1) Hydrocarbons are caused by the _____ of oil and petrol and it effects the environment with carcinogen.
2) Radioactive isotopes which are caused by small _____ from nuclear waste and nuclear accidents have a carcinogenic effect on the environment as well.
3) Besides that optical effect it causes an increase of ozone in the lower _____ and the health conditions of the particular organism living in such an area.
4) In Scandinavia, which receives a high proportion of its air _____ from Britain, once productive lakes are now completely devoid of fish.
5) Emissions of dust can and should be controlled by filters which remove _____ before gases are discharged.
6) More and more often people are told not to be in direct sunlight, because _____ radiation from the sun can cause skin cancer.
7) There is no ocean or sea which is not used as a _____.
8) It may be that the medicines we need will be discovered in _____ in savannas, deserts or rainforests.
9) We need to choose cheap electricity and polluting the environment and expensive electricity but _____ life and clean environment.
Задание 1. Прочитайте текст. Задайте вопросы к выделенным предложениям
A new atomic clock being developed for navigation satellites will perform better than previous devices. The clock, which incorporates a hydrogen maser, will use new microwave cavity design to provide a compact and lightweight package, and new electronic techniques to maintain long-term stability. The clock can provide precise navigation information because it is stable to one second in three million years.The differences in the time when signals from four satellites arrive at one location can be used to calculate that position to within a few yards.
Задание 2. Представьте, что вы являетесь членом организации по защите окружающей среды "Green Peace ". Напишите обращение к людям, используя модальные глаголы must, needn’t, mustn’t. Вы можете использовать следующие словосочетания:
to keep your region green; to drop litter in public places; to plant trees and flowers; to care for the animals; to pollute air with gases.
ОБУЧАЮЩИЙ МОДУЛЬ 8.2
The Atom and Its Peaceful Usage
Задание 1. Прочитайте и переведите тексты со словарем
Henri Becquerel (1852—1908), a French scientist kept a collection of curious minerals in his desk. It so happened that in this desk were several boxes of unopened photographic plates. One day he decided to open one of the boxes and discovered that the plates were not only fogged, but intensively exposed. After studying these happenings he found that they must have been caused by rays given off from a mineral "pitchblende". Further investigation showed that the rays could pass through solid substances. If these rays had no penetrating power, they would not pass through solid substances. They could make gases good conductors of electricity, just like X-rays, which had been discovered only a year before.
These new rays needed no special equipment to produce them. It was found that the heavy elements — uranium, thorium, actinium — gave out these radiations. In fact, the radiations went on naturally, and were quite unaffected by any chemical or physical action. This strange discovery was called "natural radioactivity", and scientists soon came to believe that the reasons for these happenings were to be found deep inside each atom of the substance.
Becquerel placed a piece of uranium inside a lead block, leaving only a thin hole to allow the escape of the radioactivity. By using a magnet, he showed that the radiations were of three different kinds. One was caused by negatively charged particles which the magnet bent to one side, and another kind was formed by positively charged particles, bent by the magnet in the opposite way. The third form of radiation was not bent in any way. The radiations carrying positive charges were called "alpha rays". The negatively charged particles were found to be fast electrons, and were named "beta rays". The rays that were not bent by the magnet were discovered to be X-rays of very short wave length, and were called "gamma rays". If all the particles were electrically neutral as gamma rays are, they would not be deflected by a magnetic field.
By the beginning of the 20th century man had begun to learn something of the structure of the atom. In 1896, a French scientist Becquerel made an observation that a piece of uranium ore gave out a mysterious radiation. This radiation was even more powerful than the X-rays which Roentgen had recently discovered. Year in and year out, uranium and all of its compounds send out their highly penetrating radiation. Nothing you can do in any way prevents it. Undisturbed the uranium just keeps on giving off its radiation. We call this action radioactivity;
The discovery that uranium and other elements possessed radioactive properties led to a systematic search by the Curies. They found that thorium and its compounds acted like uranium, too. They also noticed that pitchblende, an ore of uranium, was more radioactive than pure uranium itself. So they decided that pitchblende must contain an unknown substance much more radioactive than uranium.
Many years of untiring work passed before Irene Curie, after the death of her husband, succeeded in separating of a gram of radium from many tons of pitchblende. She found that this element, radium, was more than 100,000,000 times as radioactive as uranium. The era of radioactive chemistry had arrived.
Industry and the Atom
Several designs for nuclear-powered electric generating plants are in use. One of these designs is illustrated by this model and diagram.
The velocity of the fragments produced by fission in the reactor corresponds to a temperature of about 600 billion degrees Celsius (one trillion degrees Fahrenheit). No way has yet been found to utilize this tremendous heat energy directly. Instead a coolant, such as liquid sodium or water, may be circulated through the reactor to absorb part of this heat. The coolant is then piped under high pressure to an exchanger, where it passes through coils surrounded by water at a lower pressure and lower temperature. As this water becomes heated, it changes to steam which is then used to operate a turbine. The turbine, in turn, powers a generator which produces electricity. The spent steam is cooled to its liquid state in the condenser and pumped back to the heat exchanger.
Nuclear fuels are much easier to transport. This is particularly important for designers of ships and planes. Atomic-powered submarines and ships have already been built which are capable of sailing around the world without stopping to refuel.
New fissionable materials are an important by-product of the reactor. Thorium and normal uranium are not fissionable in their natural state. But, when they are irradiated with neutrons, they are changed into fissionable isotopes that can be used as nuclear fuel.
Isotopes of many other elements can be produced by irradiation in a reactor. These isotopes are used in a number of interesting industrial processes. But, more important, is their great value to plant science, animal biology, and medicine.
Plants and the Atom
Scientists are studying the effects of atomic radiation on plants. Exposure to atomic radiation produces a number of interesting changes in the structure and functions of plants and their offspring. The study of these changes is leading to a better understanding of the nature of plant life. Some of the discoveries may result in the development of better crop plants.
For many years, scientists have known which elements occur in plants and their proportion. But they were not certain how the various elements entered the plant, nor did they understand the action of the elements within the plant.
Recently, however, plant scientists have learned to trace "tagged" atoms — radioactive isotopes which release small amounts of radiation — by the use of radiation detecting devices. When a few "tagged" atoms are mixed with normal ones, the movement of an element can be followed from the soil, through the plant, until it is stored in tissue or discharged from the plant. Atomic research already has led to many advances in our knowledge of plant life. These discoveries have been put to many practical uses, including the improvement of fertilizing technique.
Animals and the Atom
Radioactive isotopes are revealing new facts about animals, too. Scientists can follow changes which occur in various chemicals from the instant they enter an animal's body until they leave it. To determine how a cow manufactures milk, radioactive isotopes were added to the animal's food and injected into various parts of its body. Tracer elements are also used to study how hens make eggs. Scientists are using tracers to follow the activities and processes of mice, fish, flies, and other animals.
"Tagged" atoms are widely used in medicine. The discovery that iodine always collects in the thyroid gland led to the development of a new method of treating cancer of that organ. Radioactive iodine taken by a patient accumulates in the thyroid and its radiations kill the cancer cells.
Scientists are now searching for chemicals that accumulate selectively, in other organs of the body. When a harmless radioactive gas is taken into the lungs of a patient it is carried to the left side of the heart. If radioactivity is detected immediately in blood samples drawn from an artery supplied by the right side of the heart, surgeons know that there is a leak between the two chambers of the heart.
Research workers are also studying the harmful effect of radiation on the human body. Experiments which may cause malformations cannot be performed on humans. Much data valuable to medicine is therefore obtained by studying the effect of radiation upon animals.
Задание 2. Заполните таблицу, опираясь на тексты
Задание 1. Прочитайте и переведите тексты
The Largest Nuclear Complex in the World “Mayak”
«Mayak» is a nuclear fuel reprocessing plant between the towns of Kasli and Kyshtym 72 km northwest of Chelyabinsk in Russia. The plant is located in the Ozersk central administrative territorial unit, formerly known as Chelyabinsk-40, later as Chelyabinsk-65, and the part of the Chelyabinsk Oblast.
The “Mayak” plant was built in 1945-48, in a great hurry and in total secrecy, as the part of the Soviet Union's nuclear weapon program. The plant's original mission was to make, refine, and machine plutonium for weapons. Five nuclear reactors were built for this purpose. Later the plant came to specialize in reprocessing plutonium from decommissioned weapons, and waste from nuclear reactors. Today the plant makes tritium and radioisotopes, but no plutonium. In recent years, proposals that the plant reprocess waste from foreign nuclear reactors have given rise to controversy. Now plans are being made to import 20,000 tones of nuclear waste in exchange for over 20 billion US dollars. Potential exporting countries include: Japan, South Korea, Taiwan, Bulgaria, Hungary, Switzerland, Germany and Spain. Russian authorities now hope to negotiate future reprocessing contracts with Switzerland, Spain, South Korea, Slovenia, Italy, Belgium, and Slovakia.
In the early years of its operation, the “Mayak” plant released quantities of radioactively contaminated water into several small lakes near the plant, and into the Techa river, the source of drinking water for many villages. It exposed 124,000 people to medium- and high levels of radiation.
Working conditions at “Mayak” resulted in severe health hazards and accidents. The most notable accident occurred on 29 September 1957, when the failure of the cooling system for a tank storing tens of thousands of tons of dissolved nuclear waste resulted in a non-nuclear explosion having a force estimated at about 75 tons of TNT, which released some 2 million Curies of radioactivity over 15,000 sq. miles. Some villagers were evacuated, but many were not. At least 272,000 people were affected by radiation. Hundreds of square miles were left barren and unusable for decades and maybe centuries. Today, around 7,000 people still live in direct contact with the highly polluted Techa river or on contaminated land.
Последнее изменение этой страницы: 2016-04-19; Нарушение авторского права страницы
infopedia.su Все материалы представленные на сайте исключительно с целью ознакомления читателями и не преследуют коммерческих целей или нарушение авторских прав. Обратная связь - 220.127.116.11 (0.011 с.)