Экзамен по английскому языку
- Письменный перевод английского текста со словарем (3 тысячи знаков).
- Пересказ английского текста (на английском), взятого из английского журнала, без словаря (2 тысячи знаков).
- Аудирование (1,5 тысячи знаков).
- Беседа о научной деятельности (на английском языке).
Пример текста для письменного перевода (вар. 1)
Пример текста для письменного перевода со словарем — облегченный вариант, — 2100 зн.
The concept of hydrogen energy system, proposing the transfer of power engineering industry and transport to hydrogen, was born in mid 1970s, against a background of the worldwide oil crisis. The main attention was paid at that time to the improvement of technical and economic indices of hydrogen production as well as to increase the efficiency of its consumption. At the same time, hydrogen production, storage and transportation remained in shadow. During 1970s the factor of environment hazard began to be introduced into economic calculators, the ecological cleanness of hydrogen made its usage in a number of production processes potentially profitable. Simultaneously, solution for hydrogen storage problem world over became a reality for scientific community.
The problem of hydrogen storage is clearly connected to the necessity of development of reliable and effective methods of hydrogen compression. Hydrogen often behaves as an element of the halogen group like fluorine or chlorine. Forming hydrocarbons like methane, gasoline and all sorts of plastics. In the periodic system, however, Mendelejiv positioned it above the alkali metals on the basis of its mass and it stayed there as it has a single electron in the s-shell like all elements in the last row. When hydrogen behaves like metal it forms compounds with metals like Li, Na, Mg, Ti, which generally known as metal hydride. Generally the Miedema model applies, which says that the more stable an interrnetallic compound is, the less stable its hydride and vice versa. These metals form initially a solid solution of the a-phase when they are hydrided and the lattice of this a-phase expands as each hydrogen atom adds an effective volume of 2−3 A3. The a-phase is characterized by a relatively low hydrogen concentration, so that the interactions between hydrogen atoms are weak and mobility is generally very high. Mutual interactions between dissolved hydrogen atoms cause a gas liquid a-p transition when the hydrogen concentration increases. The whole process of hydride formation for gaseous hydrogen can be described by the PCI curves as shown in Fig.1.
The problem of hydrogen storage is clearly connected to the necessity of development of reliable and effective methods of hydrogen compression. Hydrogen often behaves as an element of the halogen group like fluorine or chlorine. Forming hydrocarbons like methane, gasoline and all sorts of plastics. In the periodic system, however, Mendelejiv positioned it above the alkali metals on the basis of its mass and it stayed there as it has a single electron in the s-shell like all elements in the last row. When hydrogen behaves like metal it forms compounds with metals like Li, Na, Mg, Ti, which generally known as metal hydride. Generally the Miedema model applies, which says that the more stable an interrnetallic compound is, the less stable its hydride and vice versa. These metals form initially a solid solution of the a-phase when they are hydrided and the lattice of this a-phase expands as each hydrogen atom adds an effective volume of 2−3 A3. The a-phase is characterized by a relatively low hydrogen concentration, so that the interactions between hydrogen atoms are weak and mobility is generally very high. Mutual interactions between dissolved hydrogen atoms cause a gas liquid a-p transition when the hydrogen concentration increases. The whole process of hydride formation for gaseous hydrogen can be described by the PCI curves as shown in Fig.1.
Пример текста для письменного перевода (вар. 2)
Пример текста для письменного перевода, вариант 2 — 2100 зн.
The ball milling / mechanical milling has shown a path to overcome this problem which relies on mechanical impact and friction to refine and alloy powder materials. Mechanical alloying can lead to several changes by the introduction of structural defects, phase change, and /or crystallinity. A heavily defected or amorphous structure possesses different hydriding characteristics from the crystalline counterpart. Usually, hydrogen atoms occupy similar interstitial sites in the amorphous structure to those in the crystalline structure, but the binding energy of the interstitial site varies, due to heavy and varied lattice distortion in the former. Zaluska et al. has investigated the improvement in the both morphology of the Mg powder and the surface activity for hydrogenation. Depending on the ball milling conditions, the shift of the onset of desorption temperature can be as large as 100C for MgH2 and 40C for Mg2NiH4. It has been found that with the decrease in crystal grain size, the desorption energy decreases drastically, reducing the desorption temperature up to 200 °C. Another approach has been adopted in the form of milling under hydrogen atmosphere which provides a easy way to diffuse hydrogen into the material. The results indicated that the pulverization and deformation processes occurring during high energy ball milling play a major role in the hydriding reaction. So it is concluded that nano-structured materials can provide much better results for storing high content of hydrogen with fast kinetics. However, the preparation of such small particles by ball milling at large scale is a major challenge. Recent work has indicated an alternative method to prepare large amounts of nanometer-sized non-oxidized magnesium crystallites. The method is based on infiltration of nanoporous carbon with molten magnesium. The size of thus prepared Mg crystallites has been reported from 2−5 nm to less than 2 nm. Another alternative for ball milling to modify the microstructure of the material is Equal channel angular pressing technique.
Пример текста для пересказа
Примерный текст для реферирования — 1500 знаков
Ученые из Университета Саутгемптона (Великобритания) считают, что между метаматериалами и металлической или диэлектрической пластиной может возникать принципиально новая оптическая сила. Она может быть сильнее земного притяжения, что потенциально открывает широкий ряд применений в различных высокотехнологических отраслях и наноисследованиях.
Метаматериалы, имеющие особые и управляемые оптические свойства, могут иметь на поверхности плазмоны — слабые колебания электронов. Амплитуда колебания измеряется в нанометрах и приблизительно соотносится с длиной видимого света. Плазмоны взаимодействуют с электронами материала, из которого состоит пластина, в результате чего, теоретически, наноматериал и пластина должны притянуться друг к другу.
Более того, весь процесс может управляться с помощью света. Меняя частоту и интенсивность светового излучения, в результате чего меняется оказываемое им давление, можно влиять на притяжение, считают английские ученые. Другими словами, силу можно приводить в действие или прекращать быстро и просто. Чтобы более точно объяснить, о чем идет речь, Джо Чжан и коллеги приводят в качестве примера пальцы ящерицы геккона. С помощью ван-дер-ваальсовых сил пресмыкающееся способно перемещаться практически по любой вертикальной поверхности.
По словам физиков, эту силу обнаружить будет довольно легко. В скором времени планируется начало экспериментов, первые результаты которых хотят представить через несколько недель или месяцев.
Метаматериалы, имеющие особые и управляемые оптические свойства, могут иметь на поверхности плазмоны — слабые колебания электронов. Амплитуда колебания измеряется в нанометрах и приблизительно соотносится с длиной видимого света. Плазмоны взаимодействуют с электронами материала, из которого состоит пластина, в результате чего, теоретически, наноматериал и пластина должны притянуться друг к другу.
Более того, весь процесс может управляться с помощью света. Меняя частоту и интенсивность светового излучения, в результате чего меняется оказываемое им давление, можно влиять на притяжение, считают английские ученые. Другими словами, силу можно приводить в действие или прекращать быстро и просто. Чтобы более точно объяснить, о чем идет речь, Джо Чжан и коллеги приводят в качестве примера пальцы ящерицы геккона. С помощью ван-дер-ваальсовых сил пресмыкающееся способно перемещаться практически по любой вертикальной поверхности.
По словам физиков, эту силу обнаружить будет довольно легко. В скором времени планируется начало экспериментов, первые результаты которых хотят представить через несколько недель или месяцев.
- геккон gecko
- пресмыкающееся reptile
Пример текста для аудирования
Пример текста для аудирования — 1500 зн.
Semiconductor nanowires have witnessed an explosion of interest in the last few years because of advances in synthesis and the unique thermal, optoelectronic, chemical, and mechanical properties of these materials. The potential applications of single-crystalline nanowires are truly impressive, including computational technology, communications, spectroscopic sensing, alternative energy, and the biological sciences.
While lithographic Si processes are rapidly approaching their physical size limits, optical information processing promises to be a low-power, high-bandwidth alternative for the continuation of Moore’s law. In the context of global energy needs, low-cost solution-phase nanowire synthesis has also sparked interest in novel solar cell architectures that may play a significant role in the renewable energy sector. Additionally, the use of compact, integrated optical sensors can be envisioned for the detection of pathogenic molecules in the arena of national security or for the diagnosis and study of human disease. This breadth of application naturally requires a multidisciplinary community, including but not limited to materials scientists, chemists, engineers, physicists, and microbiologists, all coming together to solve challenging optical problems at nanometer length scales. However, it is essential for the materials to be synthesized and characterized before the exploration of their properties and applications can take place.
Possible questions:
1) Why have semiconductor nanowires become so popular recently?
2) What are, according to the text, the potential applications of single-crystalline nanowires?
3) What does this breadth of applications require?
While lithographic Si processes are rapidly approaching their physical size limits, optical information processing promises to be a low-power, high-bandwidth alternative for the continuation of Moore’s law. In the context of global energy needs, low-cost solution-phase nanowire synthesis has also sparked interest in novel solar cell architectures that may play a significant role in the renewable energy sector. Additionally, the use of compact, integrated optical sensors can be envisioned for the detection of pathogenic molecules in the arena of national security or for the diagnosis and study of human disease. This breadth of application naturally requires a multidisciplinary community, including but not limited to materials scientists, chemists, engineers, physicists, and microbiologists, all coming together to solve challenging optical problems at nanometer length scales. However, it is essential for the materials to be synthesized and characterized before the exploration of their properties and applications can take place.
Possible questions:
1) Why have semiconductor nanowires become so popular recently?
2) What are, according to the text, the potential applications of single-crystalline nanowires?
3) What does this breadth of applications require?