Score
Title
90
AskScience Panel of Scientists XVIII
269
AskScience AMA Series: "I am Rhett Allain, physicist and technical consultant on Mythbusters and MacGyver. Ask me about the physics of pretty much anything!
34700
Why is it that during winter it's not uncommon to have days with abnormally high temperature and summer-like weather, but in the summer it never drops to winter-like weather for a day?
198
If 2 people dislike the same food, are they then more likely to dislike other similar foods?
12
Whats the truth about applying water to burns? Will cold water cause it to blister or stifle it? What about lukewarm water?
11
If both the liver and the kidney are filtering organs, what are their different responsibilities? Are there other organs that perform similar functions?
8
Are there any materials that only allow radio waves to pass through in one direction?
52
Does the Mach Cone occurs only appears when crossing the 1 Mach speed or it can also appear later during the supersonic flight (> 1 Mach)?
11
Are there positions of a chess board that are impossible to achieve legally?
29
What was going on in the science community when the first dinosaur bones were discovered? Did we realize early on what we were looking at? What was the attitude of the community towards the discovery?
5
Why does water make paper products translucent?
18
Could a planet with a highly eccentric orbit be tidally locked?
2
Why do martian rovers last so much longer than planned?
3
How are the eggs of birds formed and what is the process called? Are they formed to the size that they are eventually hatched?
538
Can dogs observe and recognize aging in adult humans? Do they differentiate between young adult, middle-aged and elderly humans?
3
What physically happens inside a computer when it crashes or freezes?
3
Is energy gain relative?
6
Is there a theoretical limit to how many protons an atom can contain?
8
At what frequency does a repetitive sound become a solid sound?
25
Why don't the palms of our hands and the soles of our feet tan or burn?
9
Does the gravitational force of the sun and moon affect the atmosphere the same way it affects the tide? Is there an increase in oxygen during high tide/low tide?
8
Are there any known mutations in drosophila melanogaster that cause a phenotype of folded downward wings?
7
Why are there so few species of mammals?
11
Is it possible to trigger or "activate" a volcanic eruption?
0
If Earth were larger, would it move closer to the sun or farther away?
11004
When does a mushroom die? When it's picked? When it's packaged? Refrigerated? Sliced? Digested?
6
Are blood bags usually sealed (in a vacuum)?
12
When you physically break or shatter a flash storage chip, to what degree is the data still readable from the fragments?
1
How uneven can London Dispersion Forces make an atom?
2
Is white light dispersed by a prism always the same? (angles to colour)?
2
When receiving donated blood, how do u screen for blood diseases before releasing them to hospitals?
3
Does energy accumulate in geographical faults in such a manner that the longer that energy isn't released, the bigger energy-releases we can expect at once? (i.e. earthquakes, volcanos).
40
Is it possible to transform martian soil into fertile soil through bacteria and fungi?
22
Do cats purr voluntarily or unvoluntarily?
7
How do processors make sure their calculations are done correctly when out of the billions of transistors they have, a few will surely fail over time?
6
Are seatbelt/phone detection cameras a real thing? And if so, how do they work?
16
What is the most amount of electrons forcibly added to an atom?
12
Why does the taste of tap water vary between locations?
5
Is there Ice at the bottom of Challenger Deep?
4
Can the Maillard reaction be reversed? Or, Is it possible to untoast bread?
54
Why do things like saliva or melted cheese pull into strings when you try to separate them?
11
Do any of the stars we can observe with tbe naked eye at night have planets orbiting them?
7 NanotechNinja I use scanning tunneling microscopy (STM), which is a similar probe technique to AFM. (It has the "restriction" that you can only measure conductive samples, whereas AFM can measure insulators, but it allows you to get additional electronic information in addition to topology.) Our tips are made of polycrystalline tungsten wire, 0.25mm in diameter. We prepare them by a fairly standard electrochemical etching method, as follows. 1. A small beaker is filled with a solution of potassium hydroxide. 2. A ring shaped wire is positioned at the surface of the solution 3. The tip wire is suspended partially in the solution in the middle of the ring, and a voltage is applied between ring and tip wire. 4. This causes the tip wire to etch preferentially at the surface of the solution. 5. The weight of the section of the tip in the solution causes the area being etched to stretch out as it gets etched. 6. At some point, the lower section of the wire drops off. This has an associated drop in current, which we use as an indicator to stop the etching. (This is pretty important, if you don't stop the etching as soon as possible after dropoff, the newly formed tip gets blunter; the electronic trigger which detects current drop stops the voltage in about a microsecond) 7. The tip is rinsed in deionized water (to remove KOH residue) and inserted into ultra high vacuum ASAP. By this method we routinely achieve tips sharp enough for atomic resolution measurements. For standard AFM, I know that people typically use silicon nitride tips. I believe these are made by standard photolithography processes with a silicon wafer, and then the nitride layer is grown on top.
9 whitcwa Early on, they were made by smashing diamonds with hammers and then looking for good candidates with an optical microscope. They don't need to be smaller than the atoms they are imaging. If you use a rounded 25mm broomstick end, you can easily feel a 1mm bump.
4 bearsnchairs Some specialized AFM tips have a CO molecule on them, for subatomic resolution. http://aip.scitation.org/doi/abs/10.1063/1.4934273?journalCode=apl The reason why CO is used is because oxygen is one of the smallest atoms, and the CO bond is very stable and you don’t need to worry as much about it reacting with your surface like you might with fluorine.
4 cantgetno197 I don't know much about how they're made, though I'd imagine it's using the same techniques they use for all MEMs, which is basically what they are. You can read some basics on MEM fabrication process flow here: https://en.wikipedia.org/wiki/Microelectromechanical_systems#MEMS_basic_processes But they're definitely not smaller than the atoms they're manipulating. The tips are in the nanometers to 10s of nanometers range in size I believe. Which is about ~100-1,000 atoms wide.
8 0 NanotechNinja I use scanning tunneling microscopy (STM), which is a similar probe technique to AFM. (It has the "restriction" that you can only measure conductive samples, whereas AFM can measure insulators, but it allows you to get additional electronic information in addition to topology.) Our tips are made of polycrystalline tungsten wire, 0.25mm in diameter. We prepare them by a fairly standard electrochemical etching method, as follows. 1. A small beaker is filled with a solution of potassium hydroxide. 2. A ring shaped wire is positioned at the surface of the solution 3. The tip wire is suspended partially in the solution in the middle of the ring, and a voltage is applied between ring and tip wire. 4. This causes the tip wire to etch preferentially at the surface of the solution. 5. The weight of the section of the tip in the solution causes the area being etched to stretch out as it gets etched. 6. At some point, the lower section of the wire drops off. This has an associated drop in current, which we use as an indicator to stop the etching. (This is pretty important, if you don't stop the etching as soon as possible after dropoff, the newly formed tip gets blunter; the electronic trigger which detects current drop stops the voltage in about a microsecond) 7. The tip is rinsed in deionized water (to remove KOH residue) and inserted into ultra high vacuum ASAP. By this method we routinely achieve tips sharp enough for atomic resolution measurements. For standard AFM, I know that people typically use silicon nitride tips. I believe these are made by standard photolithography processes with a silicon wafer, and then the nitride layer is grown on top.
9 0 whitcwa Early on, they were made by smashing diamonds with hammers and then looking for good candidates with an optical microscope. They don't need to be smaller than the atoms they are imaging. If you use a rounded 25mm broomstick end, you can easily feel a 1mm bump.
5 0 bearsnchairs Some specialized AFM tips have a CO molecule on them, for subatomic resolution. http://aip.scitation.org/doi/abs/10.1063/1.4934273?journalCode=apl The reason why CO is used is because oxygen is one of the smallest atoms, and the CO bond is very stable and you don’t need to worry as much about it reacting with your surface like you might with fluorine.
4 0 cantgetno197 I don't know much about how they're made, though I'd imagine it's using the same techniques they use for all MEMs, which is basically what they are. You can read some basics on MEM fabrication process flow here: https://en.wikipedia.org/wiki/Microelectromechanical_systems#MEMS_basic_processes But they're definitely not smaller than the atoms they're manipulating. The tips are in the nanometers to 10s of nanometers range in size I believe. Which is about ~100-1,000 atoms wide.