Stable Isotopes

The range of application of stable isotopes is very wide indeed. They have become an indispensable means for solving problems associated with modern research work and industrial production. Stable isotopes can be used without special safe­ty precautions in any laboratory.

Chemical changes caused by radioactive effects invariably associated with the use of radioactive isotopes do not occur in the use of non-radiant stable isotopes.

The use of stable isotopes differs in no way from the use of normal chemical substances as far as safety precautions are concerned. Stable isotopes are a valuable means for investi­gating reaction mechanisms.

Grammar: 1. The Emphatic Construction. The use of for. Revision of the Participle. Text: Some Semiconducting Materials. Lesson 15

selenide I'selinaid] telluride ['teljuraid] synthesis ['sinBisis] amorphous [o'mmfos] conventional [kon'venjonl] analogue f'senobgj

supercool ['sju:poku:l] advent ['aeavont] range [remd3]

transparency [traens'pearonsi] conductivity /kondAk'tiviti] vitreous ['vitrias]

Ex. 1. Pronounce the following words:

accidental [^seksi'dentl] technique [tek'nr.k]

chalcogenous glass [ksl'kadsmas 'glasj

Ex. 2. Read the following word combinations fluently:

semiconducting materials ['semikan'dAktig ma'tiaralz] a wide range of glasses [э 'waid 'remds 3v 'glasiz] chemical analogues ['kemikal 'aenalogz] a set of required conditions [э bet av ri'kwaiad kan'dijbnzj compared with the oxide [kam'pead wi3 5i -oksaid] a far lower softening point [a 'fa: -loua 'safnig 'paint] their radiation resistance [dea ,reidi'eijbn ri'zistans]

Ex. 3. Translate the following sentences according to the given models!

Model I: It was M. V. Lomonosov who founded the first University in Russia.

(Именно) M. В. Ломоносов основал первый университет в России.

1. It is this article that shows the progress of our industry.

3. It was D. I. Mendeleyev who first classified the elements according to their atomic weights. 3. It is the development of chemical processes that his report deals with. 4. It was not until 1911 that the first theory of atomic structure was suggest­ed. 5. It was in the Soviet Union that the first atomic power station was built. 6. It was the Dutch physicist, Christian Huygens, who offered an explanation for this new phenom­enon.

Model II: I do know this man very well.

Я действительно знаю этого человека очень хорошо.

1. Though these molecules are very small the examina­tion under a'very powerful electronic microscope may show that they do exist. 2. He did carry out this experiment with­out any outside help. 3. Water does dissolve some substances readily. 4. This metal does conduct electricity well. 5. Though this subject was very difficult for him he did master it well. 6. All of the weight relations in chemical reactions do depend upon the weights of the atoms of the elements. 7. The process of extraction does involve four steps. 8. These electrode reactions, like other chemical reactions, do occur in steps.

Ex. 4. Find the English equivalents of the following Russian sentences:

I. Именно этот полупроводник был использован в этом приборе нашими научными сотрудниками.