1. What problem does a group of researchers appear to have solved?
a) the problem of pasta-shaped radio waves
b) the problem of radio congestion
c) the problem of the University of Padova
2. How can a wave twist about its axis?
a) a certain number of times
b) in either a clockwise or anti-clockwise direction
3. Even in the very same frequency band, each of the twisted beams can be .
a) generated and detected
b) independently generated, propagated and detected
4. What did the researchers do to demonstrate the solution?
a) transmitted two twisted radio waves over a distance of 442 metres
b) transmitted two twisted radio waves in the 2.4 GHz band over a distance of 442 metres
c) cooked two plates of fusillli-pasta
5. How is it possible to obtain 55 channels in the same frequency band?
a) using multiplexing
b) using five orbital angular momentum states
Task 5. Choose the correct words.
1. A method for generating and detecting twisted radio waves / fusillli-pasta could lead to an explosion in the number of available communication channels.
2. A group of Italian and Swedish researchers appears to have solved the problem of radio jam / congestion.
3. The number of radio frequency gangs / bands available to broadcast information gets smaller and smaller.
4. The twisted beams behave as independent communication canals / channels.
5. The researchers transmitted two twisted radio waves to a satellite plate /dish.
Task 6. Complete the sentences according to the text «Pasta-shaped Radio Waves Beamed across Venice» in your own words.
1. A group of Italian and Swedish researchers … .
2. A solution to the congested bands is … .
3. A wave can twist … .
4. It is possible to obtain… .
Task 7. Write a summary of the text «Pasta-shaped Radio Waves Beamed across Venice».
UNIT 4. NANOTECHNOLOGY AROUND US
«In thinking about nanotechnology today, what's most important is understanding where it leads, what nanotechnology will look like after we reach the assembler breakthrough».
K. Eric Drexler
|absorb ( V ) – поглощать altitude ( N ) – высота над уровнем моря, pl . возвышенность, высокая местность benefit ( N ) – выгода, преимущество bump ( N ) – изгиб, выпуклость cell ( N ) – клетка challenge ( N ) – сложная задача, проблема constructive ( Adj ) – конструктивный, созидательный consumption ( N ) – потребление contaminate (V) – загрязнять destructive ( Adj ) – деструктивный, ослабляющий dimension ( N ) – измерение, величина||enhance ( V ) – усилить, улучшить evolve ( V ) – обнаруживать, filament ( N ) – волокно, нить hexagonal ( Adj ) – шестиугольный hollow ( Adj ) – пустой, полый interference (N) – интерференция выделять (тепло), издавать (звук) multilayer (Adj) – многослойный nanoscale (N) – наноразмерный nanometer ( N ) – миллимикрон, нанометр, нм nanostructure ( N ) – наноструктура nanotechnology ( N ) – нанотехнология pattern ( N ) – образец, рисунок reflectance ( N ) – коэффициент отражения, отражательная способность|
Task 1. Discuss with a partner.
1. Do you agree or disagree with the quotation above?
2. Is «nanotechnology» important (revolutionary, transformative, powerful, dangerous, beneficial)?
3. Are there examples of nanostructures in nature?
Task 2. Read the text and say the examples of nanostructures in nature.
Nanostructures in Nature
Nanostructures – objects with nanometer scale features – are not new nor were they first created by man. There are many examples of nanostructures in nature in the way that plants and animals have evolved.
On the surface of a butterfly’s wings are multilayer nanoscale patterns. These structures filter light and reflect mostly one wavelength, so we see a single bright colour. For instance the wings of the male Morpho Rhetenor appear bright blue. But the wing material is not, in fact, blue; it just appears blue because of particular nanostructures on the surface. The nanostructures on the butterfly’s wings are about the same size as the wavelength of visible light and because of the multiple layers in these structures optical interferences are created. There is constructive interference for a given wavelength (around 450nm for the Morpho Rhetenor) and destructive interferences for the other wavelengths, so we see a very bright blue colour. In the laboratory, many scientific instruments use this same phenomena to analyze the colour of light.
A moth’s eye has very small bumps on its surface. They have a hexagonal shape and are a few hundred nanometers tall and apart. Because these patterns are smaller than the wavelength of visible light (350-800nm), the eye surface has a very low reflectance for the visible light so the moth’s eye can absorb more light. The moth can see much better than humans in dim or dark conditions because these nanostructures absorb light very efficiently. In the lab, scientists have used similar man-made nanostructures to enhance the absorption of infra-red light (heat) in a type of power source (a thermo-voltaic cell) to make them more efficient!
The edelweiss (Leontopodium nivale) is an alpine flower which lives at high altitudes, up to 3000m / 10,000 ft, where UV radiation is strong. The flowers are covered with thin hollow filaments that have nanoscale structures (100-200nm) on their periphery. They will absorb ultraviolet light, which wavelength is around the same dimension as the filaments, but reflect all visible light. This explains the white colour of the flower. Because the layer of filaments absorbs UV light, it also protects the flower’s cells from possible damage due to this high-energy radiation.
Дата: 2018-12-28, просмотров: 258.