# Tag Info

8

It's not simply a matter of size. Generally nanoparticles are a few nm to 100 nm and most molecules are smaller. But, for example, single chain of a high molecular weight polymer or a DNA molecule can easily be much larger than 100 nm which would put it outside the conventional "nano" range. The distinction is somewhat fuzzy. Is a fullerene a molecule or a ...

7

Quite likely, the two materials would stick together and form a seamless bond. If you have two two identical crystal lattices, and each one is bond-deficient at the surface, it will be energetically favorable for the surfaces to bond. Moreover, by making the surfaces as flat as possible, you have made it likely that large-scale alignment will occur. Think ...

5

A nanoparticle as typically used in nanotechnology refers to a particle with diameter on the order of 1-100 nanometers, or $10^{-9}$ to $10^{-7}$ meters. However, it's not just a matter of size. These particles are not typically "molecular" in the sense that they are not stoichiometric units made out of atoms held together by covalent bonds. Indeed, most ...

5

It has to do with size. A molecule is in the range of picometers. A carbon-carbon bond is 154 picometers, so you expect most molecules to fall within the range 100-1000 picometers = 0.1 to 1 nanometers. A big molecule, such as a ribosome, or DNA, falls in the range of 10-1000 nanometers. Everything that falls in this range is "nano" by very nature. ...

4

I think the real answer is that when it comes to nanorobots, the materials we're using readily oxidise. Put them out of a vaccum and they're toast the instant they come into contact with the atomosphere. Biology manages to deal with this by using a different material set, and encapsulating everything pretty well so that the environment doesn't damage cell ...

4

The website is clearly supported by lots of money which doesn't guarantee that it reflects the most accurate scientific information. The very page you quoted says under the picture: The material is graphene, also known as graphite... Well, no. Graphene is not the same thing as graphite. Graphite is a 3-dimensional material used to produce pencils - and ...

4

In the picure below, you can see how the row-column grid correspond to the graphene structure. To have a (n,m) nanotube, you "just" have to roll your graphene sheet so that the (0,0) hexagon coincides with the (n,m) hexagon. Of course, it is much easier said than done !

4

A carbon nanotube can be seen as a sheet of graphene that is "rolled up". Now, graphene is a two-dimensional lattice and hence has two lattice vectors, $\vec{a}_1$ and $\vec{a}_2$. (If you are unfamiliar with lattice vectors let me know and I will expand on this). The numbers $(n,m)$ simply state that your tube is obtained from taking one atom of the ...

3

Laws of classical mechanics cannot just be scaled down to the nano-regime, as alot of additional forces come up (chemical interaction, friction must be inspected newly, cannot be described by rough material parameters as in classical mechanics). Also microfabrication is a highly tricky process, especially if u want to do it in a parallel style fabrication ...

3

The numbers will greatly vary depending on the kind of nanotube. The following are some examples from cursory Google searches. Electrical conductivity was increased by 50 percent to 1,230 siemens per meter. http://news.ncsu.edu/releases/wms-zhu-cnt-composites/ And that’s not all: colossal carbon tubes are ductile and can be stretched, which ...

2

Depends on your definition of a quantum dot. Usually they are understood to be a collection of excitons (bound states of electrons and holes) confined to a small volume. But the smaller the volume, the higher the energy of the system and eventually you would destroy the exciton bonds (besides, there would be a technical problem of how to maintain such a ...

2

This is a footnote to Chris' answer (+1 BTW :-) The microsocopic source of friction is exactly the cold welding mentioned by Chris and DJBunk. When you touch two rough surfaces together their real area of contact will be much less than the total area because only the high spots touch. At these high spots the surfaces adhere due to the same forces that act ...

2

The reason is that you have periodic boundary conditions in the azimuthal direction while there are no special constraints along the cylinder axis (note that, as in the radial direction we have the $\pi$ bonds of the carbon lattice the electron's wavefunction must be strongly confined). Other way to see this, in the azimuthal direction you must have an ...

2

I don't believe that the materials we use for engineering on the macroscopic scales, gears and wheels and metals and so forth, will be appropriate for nano-devices. Macroscopic devices are usually built out of chemically homogenous materials, which do not afford flexibility in knowing where to cut and splice to design new shapes, or how to assemble the parts ...

1

Sure - the relativistic doppler effect means that light which is scattered off a moving object can be redshifted or blueshifted. And there can be more redshifted photons than blueshifted photons, or vice-versa, depending on where the object is, and how it's moving, relative to the center of the trap. But since the object is moving much much much less than ...

1

I used an arc-welder to make thermocouples from wires like your starting materials. Your desired objective looks like some of my 'failures.' Try loading a wire in tension and then break it with an arc (i.e. heat and melt a short section.) The ends might draw to the fine diameters you're trying to achieve. I'd try using one of the welders that are designed ...

1

1) Not at all! There are many applications and examples not needing three PhDs to understand. Gosh, where to start... 2) Too many to list here, and I'm not expert, but one important general method is depositing layers onto a material, for example how transistors and other semiconductor devices are made. Vapor deposition, ion bombardment, and more. ...

1

Resistivity is the relevant parameter for three-dimensional materials. Sheet resistance (less commonly called "sheet resistivity") is the relevant parameter for two-dimensional materials, and its inverse is called "sheet conductance" or "sheet conductivity". In the Novoselov paper you cited, they talk about sheet resistance and sheet conductance. Please ...

1

normal matter structure is entirely constructed from the electronic bindings, so it is in the realm of the possible to engineer how the atoms are binded together exactly and this is the aim of lower-level nanotechnology. However, it is with current technogy and physics, impossible to create complex structures at lower scales (i.e: nuclear scale). And i don't ...

1

Your questions may be confusing your enquiry by too closely comparing DNA-based life and nanotech. Although they both operate at a nanoscale to create much larger objects they are very different in approach. DNA is the end result of many trillions of random events. Various simple molecules that tended to create more of themselves eventually resulted in more ...

1

If you read the laser fusion article in wikipedia you will see that white light is used in some designs to feed the lasers, not very efficiently. Better wave guides might improve efficiency but certainly cannot substitute for the energy concentration of lasers on the fuel pellets.

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Assuming that you have a source whose temperature is T, the best any optics system can do (in applying the energy from the source to a target) is in such a way that the target may be heated up to the temperature T. This is because of a basic law of thermodynamics: heat flows from hot things to cold things and never vice versa. There's another way of saying ...

1

A molecule is the collection of atoms all connected by covalent bonds, while a nanoparticle is any kind of particle1 with a size in the nanometer scale, that is (usually) between 1-999 nm. Also, Although the size of most molecules would fit into the above outline, individual molecules are usually not referred to as nanoparticles. 1)For example ...

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