Nanoantennas

Date: 2015-10-07; view: 613.

Palladium nanoparticle above a gold nanoantenna.
Image courtesy of Alivisatos group.

Nano means one billionth. A nanoantenna is an antenna that is very, very small, and is not used to carry our embedded sound waves from one place to another. It is used to gain understanding about what is happening on an atomic scale. An image of a gold nanoantenna created by the Paul Alivisatos group at Lawrence Berkley National Laboratory, along with researchers at the University of Stuttgart in Germany, is shown below. Above the gold nanoantenna is a palladium nanoparticle. The purpose of their research is to figure out a way to measure interactions on the atomic scale so that an extremely sensitive gas sensor – one that might be able to detect a single particle – may be created. The optical properties of palladium are altered when hydrogen atoms are nearby and this should be detectable, but the effect is so small that it is hard to measure. Measuring the presence of hydrogen gas with more commonly used techniques can be dangerous because hydrogen is very explosive.

Hydrogen can be absorbed into palladium. The hydrogen atoms situate themselves between the palladium atoms rather easily. When the hydrogen atoms sit between the palladium atoms in this way the substance is called palladium hydride. The hydrogen atoms can also easily leave the palladium. Each time hydrogen enters or leaves the palladium structure, a change in how the palladium nanoparticle interacts with electromagnetic waves occurs.

Ex.7. Answer the following questions:

a) What type of waves does an antenna propagate, receive, and/or transmit?

b) Radio waves are just one type of electromagnetic wave, aren't they?

c) Do all electromagnetic waves or only radio-waves carry the original embedded sound information through the atmosphere or space around it?

d) What are radio waves used for?

e) What way is a radio-wave created?

f) An alternating current circuit forces the electrons in the electrically conducting antenna (a transmitter or receiver) to move back and forth along the antenna, doesn't it?

g) What is a frequency-modulated wave characterized with?

h) Is a nanoantenna an antenna which is used to carry our embedded sound waves from one place to another?

i) Is there a palladium nanoparticle or a silver nanoparticle above the gold nanoantenna in an image of a gold nanoantenna created by the Paul Alivisatos group at Lawrence Berkley National Laboratory?

j) Are the optical properties of palladium altered when hydrogen atoms are nearby during the experiment described in the text?

Ex.8. Agree or disagree with the following statements:

a) An antenna is a device used only to receive electromagnetic waves;

b) A sound wave may be translated into an electronic signal that is sent to a transmitter (antenna);

c) The antenna creates an electromagnetic as well as many other types of waves that carry the original embedded sound information through the atmosphere or space around it;

d) Radio waves are used for wireless transmissions;

e) The radio wave is never created by an accelerated charge;

f) It is an alternating current circuit which forces the electrons in the electrically conducting antenna (a transmitter or receiver) to move back and forth along the antenna;

g) There are 4 ways to embed information on a wave;

i) A nanoantenna is an antenna that is very, very small and it can be sometimes used to carry our embedded sound waves from one place to another;

j) A nanoantenna is never used to gain understanding about what is happening on an atomic scale;

k) During a special experiment which was carried out at Lawrence Berkley National Laboratory a gold nanoantenna was created by the Paul Alivisatos group.

Ex.9. Read and translate the text. Find constructions of the Passive Voice:

TEXT

FORENSIC SCIENSE MYSTERYIntroduction

Almost everyone believed that he or she loves a good mystery. Mysteries are the real meat of forensic science. The study of forensic science involves the analysis and interpretation of evidence for use in a court of law. Unlike “pure” disciplines, forensics is an applied science that uses scientific principles to meet specific goals. On the job, forensic scientists are working for finding out what happened at a crime scene. Such determinations are made by looking at the physical evidence at the scene and deducing what that evidence says about the crime.

Nowadays the use of forensics in the classroom is promoting great interest in science and to improve critical-thinking skills. Forensics is an engaging field of study, partly because of its popularization from media. The so called “CSI effect,” portrayal of the work of forensic scientists in crime-solving programs, has made students aware of the discipline. Although the depictions of television crime drama are not always completely accurate, they do reflect the use of science to solve problems. Such programming often makes it clear to students that science is relevant in today's world.

For the teacher who wants to integrate various disciplines, forensic science is an ideal vehicle of teaching students. Because this multidisciplinary field includes the Earth science, physics, chemistry, biology, anatomy and physiology. In the real-world work of forensics, these areas of study happen not to be isolated, but strongly interrelated and interdependent.

Relying heavily on the scientific method, forensic science is inquiry based. Students are usually required to read, perform research, develop hypotheses, think analytically, and conduct interviews. Once their data is collected, students must analyze it, employ deductive reasoning, draw conclusions, and share their results with others. To carry out these or those experiments to solve these or those inquiries, forensics employs many standard laboratory techniques that require students to use equipment such as microscopes, glassware, balances, and hot plates. For example, in the role game “Banana Autopsy,” students take on the roles of pathologists by carrying out examinations of “victims” of foul play, drawing conclusions about the cause of death, then sewing up the “bodies.”

“Characterization of Types of Carbohydrates” is a partial inquiry in which protocols for distinguishing starch, cellulose, and glycogen are developed by students. One of the full-inquiry experiments, “Rate of Cooling,” asks students to design their own experiment to find out whether a body cools faster in air or in water. Other topics include radioactive isotopes, shoes impressions, mitochondrial DNA, probative value of class evidence, DNA, blood spatter, specific gravity, soil identification, density, emission spectra of light, latent fingerprints, chromatography, deductive reasoning, presumptive blood test, lead poisoning, trace evidence, and textile fibers. No doubt that only through the participation in forensic science, students can have classroom experiences that help them see the connections between education and everyday life.

Ex.10. Answer the following questions:

a) What are mysteries known to be according to the text?

b) What does the study of forensic science involve?

c) Why is forensics considered to be an applied science?

d) What is the use of forensics in the classroom said to promote?

e) Do the depictions of television crime drama reflect the use of science to solve problems?

f) Why is forensic science believed to be an ideal vehicle of teaching students?

g) Forensic science is inquiry based, isn't it?

h) What scientific methods does the forensics employ to carry out various experiments?

i) Do students use special equipment such as microscopes, glassware, balances, and hot plates when carrying out their experiments?

j) Do students or teachers take on the roles of pathologists by carrying out examinations of “victims” of foul play in the role game “Banana Autopsy”?

k) In what partial inquiry do students develop protocols for distinguishing starch, cellulose, and glycogen?

l) What are students asked to do in one of the full-inquiry experiments called “Rate of Cooling”?

Ex.11. Match the words with their definitions. Translate the definitions into Russian:

1. forensic; 2. mystery; 3. analysis; 4. crime; 5. goal; 6. biology; 7. skill; 8. chemistry; 9. anatomy; 10. physiology; 11.blood; 12. poison; 13. inquiry; 14. cellulose; 15. microscope; 16. glassware; 17.evidence; 18. identification; 19. experiment; 20. fingerprint.

Ex.12. Retell the text “Forensic Science Mystery”