Superconductors and Surfaces

Theory has a key role in developing and understanding modern advanced materials. In order to predict the properties of materials from fundamental physical principles, it is important to be able to calculate the electronic wave functions, densi­ties of states, optical properties, conductivities, etc. As an example, recently discovered copper-oxide materials are found to be superconducting at temperatures much higher than were previously possible.

Understanding the origin of this superconductivity is a fundamental and challenging physical problem involving new concepts and ideas, detailed calculations of various models, and careful comparisons with experimental results.

James Annett is currently working on the theory of electron states at metal surfaces, particularly for surfaces that are not ideal and that have surface steps or other imperfections. This work involves large-scale computer calculations in order to numerically solve the Schrodinger equation for electrons near the defect. These surface-step sites are very important for a number of surface phenomena, such as surface growth, chemical bonding of atoms to the surface, and ordering of the surface. The theory should lead to an improved understanding of these phenomena and, perhaps, to predictions of new properties. In previous work, James Annett has shown how the interatomic bonding within a metallic surface may differ from that in a bulk solid. This led to an explanation of why most ideal metallic surfaces are under a state of stress, and are often unstable to atomic rearrangements (reconstruction).

The other main area of James Annett's work is on the theory of high-temperature superconductivity in the metal-copper-oxides. These remarkable materials become superconducting (have perfectly zero resistance) at temperatures above the boiling point of nitrogen (seventy-seven degrees above absolute zero), which was once thought impossible. James Annett's work has focused on the possibility that the electron pairs causing the zero resistance have a different sym­metry from the pairs in ordinary superconductors, such as lead. He is also studying the electron correlations that occur because of the antiferromagnetism in these materials, which may hold the key to explaining their unusual properties.

VI. Translate these sentences into Ukrainian; underline the predicates and define their verb forms:

1. Surface-step sites are very important for a number of surface phenomena, such as surface growth, chemical bonding of atoms to the surface, and ordering of the surface.

2. The remarkable materials become superconducting at temperatures above the boiling point of nitrogen.

3. James Annett's work involves large-scale computer calculations in order to numerically solve the Schrodinger equation for electrons near the defect.

4. James Annett studies the electron correlations that occur because of the antiferromagnetism in these materials, which may hold the key to explaining their unusual properties.

5. The theory of superconductivity has a key role in developing and understanding modern advanced materials.

VII. Find in the text nouns corresponding to the following words; translate them into Ukrainian:

phenomena, metallic, bulk, atomic, high-temperature, zero, wave, careful.

VIII. Translate the following word combinations into English:

ключова роль, функції електронної хвилі, ретельні порівняння з експериментальними результатами, рівняння Шрюдінгера, хімічні зв’язки атомів з поверхнею, передбачення нових властивостей, високотемпературна надпровідність.

3 курс 2 семестр

Контрольна робота № 5

І. Underline the correct verb in the sentences and translate them into Ukrainian:

1. The group of students is/are working in the laboratory now.

2. Rob and Lucy have/has not attended the lectures for two weeks.

3. Physics was/were a very difficult subject for the student.

4. Polytechnics is/are centres for advanced courses in a wide range of subjects.

5. If the weather wasn’t/weren’t so bad, I would go away for the weekend.

II. Define the type of the conditional sentences and translate them:

1. If I had had any free time yesterday, I should have done the work myself.

2. Had he come, I should have been glad.

3. If you had repeated the rules, you would know them better now.

4. If you were more sensible, you wouldn’t have spoken to your boss like that.

5. If I had seen him yesterday, I should have asked him about it.

III. State the meaning of the Modal + Perfect Infinitive constructions in the following sentences and translate them into Ukrainian:

1. He could not have overlooked such a serious mis­take.

2. They may not have received our message.

3. She ought not to have borrowed his car without asking.

4. He could have been injured, but he wasn’t.

5. You would have used a computer specially designed to allow for certain physical changes in the atmosphere.

IV. Complete the sentences with too or enough and translate them:

1. Some people are … proud to admit that they don’t know.

2. Emma’s exam results aren’t good … to go to university.

3. The project is … expensive to get off the ground.

4. You put … much water in the measuring glass.

5. The student went to bed early last night because he was … tired to stay up late.

V. Translate the text into Ukrainian:

Forging

Forging is the shaping of a piece of metal by pushing with open or closed dies. It is usually done hot in order to reduce the required force and increase the metal's plas­ticity.

Open-die forging is usually done by hammering a part between two flat faces. It is used to make parts that are too big to be formed in a closed die or in cases where only a few parts are to be made. The earliest forging machines lifted a large hammer that was then dropped on the workpiece, but now air or steam hammers are used, since they allow greater control over the force and the rate of forming. The part is shaped by moving or turning it be­tween blows.

Closed-die forging is the shaping of hot metal within the walls of two dies that come together to enclose the workpiece on all sides. The process starts with a rod or bar cut to the length needed to fill the die. Since large, complex shapes and large strains are involved, several dies may be used to go from the initial bar to the final shape. With closed dies, parts can be made to close toler­ances so that little finish machining is required.

Two closed-die forging operations are given special names. They are upsetting and coining. Coining takes its name from the final stage of forming metal coins, where the desired imprint is formed on a metal disk that is pressed in a closed die. Coining involves small strains and is done cold. Upsetting involves a flow of the metal back upon itself. An example of this process is the push­ing of a short length of a rod through a hole, clamping the rod, and then hitting the exposed length with a die to form the head of a nail or bolt.

VI. Translate these sentences into Ukrainian; underline the predicates and define their verb forms:

1. Open-die forging is used to make parts that are too big to be formed in a closed die or in cases where only a few parts are to be made.

2. Forging is usually done hot in order to reduce the required force and increase the metal's plasticity.

3. Closed-die forging starts with a rod or bar cut to the length needed to fill the die.

4. Coining takes its name from the final stage of forming metal coins, where the desired imprint is formed on a metal disk that is pressed in a closed die.

5. The earliest forging machines lifted a large hammer that was then dropped on the workpiece.

VII. Find in the text nouns corresponding to the following words; translate them into Ukrainian:

Plas­ticity, required, hammer, complex, coin, desired, closed, short.

VIII. Translate the following words and word combinations into English:

Кування у відкритому штампі, необхідний, кування, прут (стрижень), прут (брусок), карбування, відбиток, збільшення, операція штампування.