Grafeno

 - ¿Qué es el grafeno? 
Es una sustancia de estructura laminar plana formada por hexágonos unidos por sus vértices y que en cada vértice hubiera un átomo de carbono.
- ¿Cuáles son sus características?
Su conductividad, superior a la del sílice, no desprende tanto calor ante el desplazamiento de los electrones por su superficie. De ello se deriva uno de sus principales usos: como procesador en dispositivos informáticos portátiles. Estos se han basado siempre en obleas de sílice y han registrado diversos problemas, sobre todo, en aparatos pequeños como los móviles y los ordenadores portátiles. Uno de ellos es el excesivo calentamiento por culpa del procesador, lo que deriva en pérdida de eficiencia y desgaste de los materiales. La segunda cualidad notable del grafeno está muy relacionada con la primera: para que los electrones se desplacen por su superficie, se requiere menos energía de la que precisa el sílice. Por tanto, en un dispositivo portátil, un hipotético procesador basado en grafeno conseguiría un mayor ahorro energético y duración de la batería, además de un menor calentamiento.

- Aplicaciones: 
* Los investigadores están pensando en usarlos en el futuro como reforzadores de plásticos para construir aviones o coches más ligeros y seguros.
* Se piensa en utilizarlo en la medicina en implantes de cadera, por tratarse de materiales ligeros, duros y resistentes.
* En electrónica, se aprovecha su propiedad de ser buenos emisores de electrones para diseñar nuevas pantallas planas.
* También se utilizan para fabricar memorias que almacenan más información, o baterías que almacenan más energía durante más tiempo (lo que resulta de aplicación en coches, teléfonos móviles, ordenadores portátiles...)

MARCO POLO'S ACTIVITIES

-Who was Marco Polo? He was a Venetian merchant traveler from the Venetian Republic whose travels are recorded in Il Milione, a book which did much to introduce Europeans to Central Asia and China. He learned about trading whilst his father and uncle, Niccòlo and Maffeo, travelled through Asia and apparently met Kublai Khan. In 1269, they returned to Venice to meet Marco for the first time. The three of them embarked on an epic journey to Asia, returning after 24 years to find Venice at war with Genoa; Marco was imprisoned, and dictated his stories to a cellmate. He was released in 1299, became a wealthy merchant, married and had 3 children. He died in 1324, and was buried in San Lorenzo.

-What historical period is the text from? The historical period is in the Middle Age

-What do you know about this period? It was a divided class period and in this epoch the people discovered many things about science and new form of getting confortable, like have different types of warm systems. For example: the coal. After coal, they used wood to make them warm.

-What region does the text discuss? The region was Catai.

-What do we call it nowadays? Cathay is the Anglicized version of "Catai" and an alternative name for China in English.

-Compare the technological development of the East with that of the West during this period.

The early Middle Ages coincided with the Islamic Golden Age. In this period there weren't many invents and at that time, Islamic philosophy, science, and technology were more advanced than in Western Europe. The period saw major technological advances, including the invention of the cannon, spectacles, and artesian wells, and the cross-cultural introduction of gunpowder, silk, the compass, and the astrolabe from the east; so in the Middle ages in the Eastern part of Europe had more technological development than the Western part.

-Why do you think the book was given this title? In my opinion, the book “ Libro de las maravillas” was given this title because inside of this, you can find stories about new sources to make energy that in the book's author period it was wonderful and fantastic, because it was the begining of the uses of the energy so that wasn't very known and make the people feel amazed.

-What stones do you think the text is talking about? I think the text is talking about coal because it says something about black stones that they found in the nature and that is very flammable.

-What properties and advantages do the stones in the text have? The properties and advantages are: these stones are mined from the mountains, and which glow, making flames like firewood: they are consumed completely like charcoal. They maintain a fire and produce heat for cooking better than wood. And if you make a fire at night and make sure that it catches well, it will stay alight for the whole night, right through to the morning.

EJERCICIO 9

EJERCICIO 8

EJERCICIO 7

EJERCICIO 6

EJERCICIO 5