Sciencemadness Discussion Board

Talent show - demos in 5 minutes or less?

Brain&Force - 10-4-2014 at 15:57

At my school we're having a talent show. I wasn't planning to enter it, but they did like my idea of a chemistry demonstration, so I decided, "Why not? Outreach is fun!"

So here's the thing. I have 5 minutes (likely more, but I just want to keep this short) to complete some interesting demos. As much as possible, I want to have audience involvement. Here are some of my ideas. I don't have much access to chemicals in general, so assume I haven't done any of them before. Some of these may be more physics than chemistry inclined. Please note I do not have access to a Bunsen burner.

Chemical chameleon (maybe with peroxide?)
Iodine clock reaction (possibly without starch for one run, just for variety)
Colored flames with copper, strontium, and potassium
Baking soda volcano with transition metal salts
Chemical garden with sodium silicate
Gallium/aluminum alloy and water (if I can find the gallium)
Amphoteric aluminum
Hydrogen peroxide decomposition/relighting of a glowing splint
Complexation cocktails with nickel, copper, cobalt, and possibly chromium
White-burning magnesium vs. green-burning ytterbium (maybe)
Permanganate and glycerin

Here are some more complex demos:

Curie temperature demo with terbium: a piece of terbium metal is shown to be only slightly paramagnetic, but cooling to dry ice temperatures changes that property to significant ferromagnetism. I only have small pieces, though. If I can find gadolinium it'll work much better because I just need regular ice.

Implosion demo: a sealable container is filled with extremely hot steam and then placed in freezing water, causing it to implode. I've seen this done with an oil barrel once, but I don't know what scale I'd do this in.

Heat conduction demo: a block of aluminum and a block of plastic are touched by a volunteer. Because the aluminum conducts heat better, it feels colder to the touch, but a piece of ice will melt faster when placed on it.

pH sensitive fluorescence: pyranine, the chemical that makes highlighter fluid fluoresce, appears to be sensitive to pH changes when it fluoresces (the color becomes different). I have never seen this before, so I'll have to test it first.

These are possible, but I don't know if they can be approved.

Fake blood with iron/thiocyanate
Magnesium/silver nitrate flash powder
Lithium/sodium/potassium in water (I'd probably use this to make the alkali needed for the chemical chameleon. Or I could add indicator solution to the water).

Any other ideas? I have an audition hopefully by Friday of next week (it may be earlier).

[Edited on 11.4.2014 by Brain&Force]

DraconicAcid - 10-4-2014 at 16:14

Sodium acetate supersaturation. Pour it and watch it solidify.

Mixing calcium acetate with ethanol/phenolphthalein- it turns pink and gels rapidly, then you can set the gel on fire.

If you're doing the fake blood, what you can also do is set up a series of beakers, each with a small amount of solution in the bottom. One contains thiocyanate, one contains dilute salicylic acid, one contains tea, one contains sodium hydroxide, one contains iodide with some starch. Pour a colourless, dilute solution of iron(III) chloride into each one....

Zephyr - 10-4-2014 at 16:40

Draconic Acid, do you mean a reaction sort of like this?
https://www.youtube.com/watch?v=9NZvnVPuDKA

[Edited on 11-4-2014 by Pinkhippo11]

Brain&Force - 10-4-2014 at 16:41

What happens with the ferric chloride? I know about thiocyanate and hydroxide, and I probably don't have salicylic acid, but what about the tea and the iodide? I know ferric iodide is unstable and converts to ferrous iodide and iodine. As for the tea, I have no idea what happens.

What is the calcium acetate used for in the gel demo? Can it be replaced with a different acetate for a different colored flame?

And I'd specifically like to ask if anybody's done anything with pyranine (highlighter fluid's fluorescent compound).

Also, please tell me which of my demos you don't think I should do. That'll help cut down on time.

[edit] Yay, I'm an national hazard!

[Edited on 11.4.2014 by Brain&Force]

DraconicAcid - 10-4-2014 at 16:46

Salicyclic acid can be made from aspirin easily enough- you don't need a lot. It turns purple (make it dilute, or it will look black). Tea turns black.

With the calcium acetate, it's what makes the stuff gel when you add the alcohol. I don't know if other acetates would work very well.

gdflp - 10-4-2014 at 16:47

Calcium acetate causes alcohols to thicken and gel. I don't think it can be replaced by another acetate. You could also try the methylene blue/dextrose/sodium hydroxide reaction, though on second thought it might take too long.

Zephyr - 10-4-2014 at 16:56

The methylene blue reaction that gdflp mentioned can be easily adjusted to react in a certain amount of time using different ratios of dextrose to sodium hydroxide.
Of the list you compiled my favorites would Chemical garden and the fake blood.

Zyklon-A - 10-4-2014 at 16:58

Lots of awesome and mostly safe reactions in this video.https://www.youtube.com/watch?v=ti_E2ZKZpC4#aid=P-tJI1xvIPk

Chemosynthesis - 10-4-2014 at 18:05

If not in a link, elephant's toothpaste and ghost crystals.

bismuthate - 11-4-2014 at 03:03

Reduction of dichromates or Vanadium (V) is amazing if you have the materials and would be allowed to do so.

MrHomeScientist - 11-4-2014 at 05:46

Gallium can of course be obtained from Gallium Source , and I got my gadolinium from United Nuclear.

The type of demos you do depends greatly on the age/background of the audience and how close they are to you. That tells you how advanced you can get and how big the demo needs to be. One of my favorites is "penny alchemy" (my video) for close-up shows. This requires a heat source, though, which I also bought from United Nuclear (the butane micro burner).

If you really aren't allowed to have open flames, I think the iodine clock is the most impressive. Modified slightly, it can be made even more impressive as the iodine oscillator.

Brain&Force - 11-4-2014 at 20:06

So I've narrowed the demos down to a relatively small list of ones that will be in the program:

For starters, colored flames with methanol (I wanted to do the barking dog, but decided against it because I haven't been able to make it work).

Chemical chameleon

Fake blood with thiocyanate

Complexation/precipitation cocktails:
Nickel(II) with ammonia and chloride
Copper(II) with ammonia and chloride
Cobalt(II) with ammonia and chloride
Iron(III) with ammonia and thiocyanate
Iron(III) nitrate in water, then nitric acid
(Advise me on any complexes with ammonia, thiocyanate, or chloride that may be interesting)

Iodine clock (as a show-stopper). I'll just pretend the reaction failed or something. Anyone know the kinetics for this reaction?

I'll try to figure out if I can do sodium or potassium in water.

Chemosynthesis - 11-4-2014 at 20:32

Quote: Originally posted by Brain&Force  

Iodine clock (as a show-stopper). I'll just pretend the reaction failed or something. Anyone know the kinetics for this reaction?

Good choices. I'm glad you're doing outreach.

http://www.labandtheory.com/kinetics/kinetics-reaction-mecha...
That has your rate constants on the page if you scroll down.

Brain&Force - 11-4-2014 at 20:38

I'm setting it up differently:

Beaker A: Sulfuric acid, hydrogen peroxide
Beaker B: Thiosulfate, iodide, and starch

The kinetics you mentioned are different. But thanks anyway!

Now I have to gather the materials before Tuesday...

Chemosynthesis - 11-4-2014 at 21:15

Quote: Originally posted by Brain&Force  
I'm setting it up differently:

Beaker A: Sulfuric acid, hydrogen peroxide
Beaker B: Thiosulfate, iodide, and starch

The kinetics you mentioned are different. But thanks anyway!

Now I have to gather the materials before Tuesday...

Oh, oops. This procedure?
http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_nos_ps_20.pdf
Do you want the rate law, or the actual constant?

Oscilllator - 12-4-2014 at 04:17

Elaphant toothpaste could be a good one, but make sure it works beforehand, since it can have a tendency to be rather anticlimactic.

Artemus Gordon - 13-4-2014 at 12:56

Quote: Originally posted by Oscilllator  
Elaphant toothpaste could be a good one, but make sure it works beforehand, since it can have a tendency to be rather anticlimactic.

Really? I can see how old H2O2 could cause problems. What else could?

Oscilllator - 13-4-2014 at 21:14

Low concentrations of potassium iodide, a wide-necked flask (use a volumetric one if possible) and possibly low temperature of initial reactants. You might want to try MnO2 as a catalyst instead, see how that goes.

MrHomeScientist - 14-4-2014 at 06:28

I do the elephant toothpaste demo all the time as part of my outreach. In my method, I have ~125mL 35% H2O2 in a large plastic graduated cylinder (I think 1 liter? It's about 2 inches in diameter). Solution 2 is 14g KI in 10mL water, in a small beaker. When ready, quickly dump all of the beaker into the cylinder and step back! I have my cylinder sitting inside a shallow plastic tub, which usually catches most of the foam.

My toothpaste wasn't working as well not too long ago, so I experimented a bit to fix it. Increasing the concentration of the KI solution to what I wrote above seems to have done the trick (used to use 12g). Not sure why it started failing in the first place, though, since my peroxide and iodide both tested to still be perfectly good.

Volumetric flask is a great idea - I bet that would look a lot like silly string!

Brain&Force: What problems are you having with the barking dog? That's another one I do regularly for the show. Definitely my favorite demo.

Brain&Force - 14-4-2014 at 10:13

I'm not doing elephant toothpaste - too messy.

The problem I have with the barking dog is that I can't get the alcohol (methanol) to ignite. How do you set yours up? I'll also try copper chloride for color. Or is boric acid better?

I'm also going to attempt to acquire sodium or potassium, if possible.

I also wanted to do the ignition of glycerin with permanganate, but one of my teachers said he doesn't want to have me mess with oxidizers. :(

Also, does 3% peroxide work with the iodine clock?

[Edited on 14.4.2014 by Brain&Force]

Zyklon-A - 14-4-2014 at 10:33

"Doesn't want to mess with oxidizers"? Ah, that's too bad. He's just effectively ruled out ~80% of the best reactions. Can you concentrate you peroxide?

MrHomeScientist - 14-4-2014 at 11:38

The way I do the barking dog isn't about accurate measurment, but it works quite nicely for my purposes. I have a long glass tube (~4 ft long x 1.5 in wide) that I lay on a tabletop. One rubber stopper is very loosely fit into the far end of the tube. I take a balloon and fill it with nitrous oxide gas (from a lecture bottle tank) to a certain size, then weigh it to make sure it's somewhere in the neighborhood of 0.5 - 1.0 g. My lab scale is actually too sensitive to get a good reading this way, so I just ballpark it. I then take the balloon, attach a short length of PVC tubing to the end, insert the tubing into the glass tube, and slowly let the nitrous out of the balloon. This, plus the loose stopper at the other end, helps to mix the gas with air inside the tube instead of just blowing it all out the other end. I'm certainly losing some nitrous this way, but it still works. (It's the same density as air so there's really no good way to do this, except water displacement.) After filling, I quickly firmly stopper both ends and secure with electrical tape for transport.
Next, I take two small spatula-fulls of boric acid (probably something like 0.25 g) and place this in a tiny vial. I then add 1 mL of methanol, and shake until dissolved.
On demo day, I pour this vial into the big tube, replace the stoppers, and swirl around to vaporize the alcohol. You need to vent a few times to relieve excess pressure. I usually do this about 30 minutes before the demo, to evaporate as much as possible. I then stand it upright in a tube stand I made, uncork the top and ignite with a long BBQ grill lighter. Works every time!

Boric acid is ideal here because it not only dissolves in methanol, but also reacts to form trimethylborate, which is very volatile and imparts a strong and uniform green color. I haven't tried other coloring agents.

For Na and K metals, try galliumsource. I haven't used them myself but I hear lots of good things around here.

The iodine oscillator I perform uses 4.0M hydrogen peroxide, which I make by diluting some 35% peroxide I have. I think this equates to about 15% concentration. I have a feeling it won't work very well with just 3%. Worth a try if that's all you have. Try pool supply stores for higher concentration - I found 27% as a chlorine-free oxidizer called Baquashock.


No oxidizers? Don't tell him about the nitrous oxide, hydrogen peroxide, or nitric acid he's apparently ok with!

Brain&Force - 14-4-2014 at 12:35

Never mind, I got the barking dog to work! I didn't add any coloring agents though...I'll try strontium/lithium, potassium and copper. I have boric acid somewhere.

The "barking dog" refers to burning methanol in a volumetric flask, not the nitrous oxide/carbon disulfide reaction.

I lit it in front of a room full of people and they all suddenly turned and looked at me. It really does grab audience attention!

This is only one of my teachers, Zyklonb; I think the other one trusts me more.

[Edited on 14.4.2014 by Brain&Force]

MrHomeScientist - 14-4-2014 at 14:41

Nice! I actually use a different version of the barking dog than the standard one with CS2 (as described above), but it behaves in much the same way. Just green instead of blue, and it produces no irritating fumes (SO2 in the blue version). Your demo would technically be termed more of a "whoosh bottle" I think :) I have doubts about coloring agents in that case, though. The green one works so well because it makes a volatile compound. Dissolved salts would simply crystallize out on the walls of your container, rather than contributing to flame color. I could certainly be wrong though! Let us know how it goes.

bismuthate - 14-4-2014 at 16:49

Tonight I had a science fair and I brought in a small version of the Briggs-Rauscher reaction in as a demo and the people were amazed.

Brain&Force - 15-4-2014 at 15:54

Talent show audition is tonight!

Here is the final list of demos:

Fake blood with thiocyanate
Coordination cocktails
Reduction of permanganate in acid and base
"Thunder flasks" (methanol in a 100 mL flask, methanol with copper chloride in a 1 L flask, methanol in a water cooler jug. Should I add copper chloride to the water cooler jug?)

I didn't have either concentrated peroxide or thiosulfate for the iodine clock, so I can't do that one.

The copper chloride colors the flame green quite evenly in a 1 L flask. I have access to boric acid, but I like the color of copper salts better. I also tried strontium nitrate, but this did not color the flame evenly. Interestingly, part of the flame was gray!

Brain&Force - 17-4-2014 at 12:00

Well, I got mixed results:

First of all, right off the bat, they wouldn't let me do the thunder flask demo on any scale. I'm doing this in the school auditorium (which is used for most theater productions) and they couldn't have any open flames at all, even on the smallest scale. My chemistry teacher is trying to see if he can do anything about it.

Second, it seemed to take too long to set up. It took about 10 minutes. I can attribute this to bad preparation - if I make it to the show itself, I'll take bottles with each of the necessary solutions rather than the solid salts themselves.

Third, I had issues with getting a few of the demos to work, especially those with chloride complexation. I added a saltwater solution to copper chloride, nickel chloride, and cobalt chloride, but they actually ended up forming the hexaaqua complexes instead of the tetrachloro complexes desired.

And fourth, I FORGOT TO GET A FLASK FOR WASTE DISPOSAL. That was just me being a moron.

There's a lot more to consider that it sees when you do outreach!

MrHomeScientist - 17-4-2014 at 12:09

Ooooh yes I know all about that :) You never really feel completely prepared until you've done the same show about 10 times.

In fact I just did a live demonstration event at the beginning of this month, including thermite, screaming gummy bear, and KNO3/sugar smoke bombs. I prepared everything as much as possible at home beforehand: I mixed the thermite in ziploc bags, prepared several screw-cap test tubes with some potassium chlorate, and had all smoke bombs pre-assembled and ready to light. When I got there, I really only needed to unpack and do some very minor setup. Preparation is key!

How did copper chloride in the "thunder flask" work out? How well did it color it?

Chemosynthesis - 17-4-2014 at 12:17

Quote: Originally posted by Brain&Force  

There's a lot more to consider that it sees when you do outreach!

We had a professional group for outreach that I still try and help with on occasion. What we did was have an outreach/demonstration officer who was in charge of maintaining the outreach demonstrations, and would instruct members on their performance. You may propose this to your school as it would allow for resume padding and increased operational efficiency.

Please disregard the screen name...

Töilet Plünger - 17-4-2014 at 12:52

MrHomeScientist, read above - the thunder flask worked fine with copper chloride, but I couldn't have any open flames on stage. Even if a fire marshal was present, it would not be permitted anyway. :mad: My chemistry teacher and I are trying to get that changed, if possible.

Chemosynthesis, that would be a great idea! I am about to graduate from high school, but I could propose this on a university level.

[edit] Oh, wait, I forgot to explain: I'm actually Brain&Force. I forgot I'm logged into the other account.

[Edited on 2014-4-17 by Töilet Plünger]

ElizabethGreene - 20-4-2014 at 19:03

one of the most spectacular demos I've seen is from the Periodic Table Videos folks on Youtube.

They carve two pieces of dry ice with a hollow in the middle. Then they add a large pile of Mg shavings in the hollow and light it. Then they quickly put the other piece of dry ice on top, trapping the burning Mg in the middle.

The Mg pulls the O2 off of the dry ice and leaves behind Carbon and MgOx.

Visually it's stunning.
https://www.youtube.com/watch?v=0dSMzg0UPPo

Scrap the idea if elephant toothpaste is too messy. This is in an entirely different league.

thesmug - 20-4-2014 at 19:06

Where would he get that much dry ice? Also I don't think that's safe enough that a school would allow it. But... if it is allowed that is a really cool demonstration!

MrHomeScientist - 21-4-2014 at 07:01

Dry ice is readily available at grocery stores, in 5 pound blocks (in my area, at least). Also "Dippin' Dots" ice cream stores have their product shipped in dry ice, and I once had a vendor offer to give me some (they just leave it out to sublimate after unpacking).
I've also done the dry ice & magnesium demo, with a video on my channel. Much smaller scale and quite a bit less impressive, I admit. The sparks that come off it are similar to a sparkler, and if you set it up properly I doubt there would be much risk of a fire. The clouds of CO2(g) it releases might be the bigger problem if done in a confined space!

And Brain&Force, you just blew my mind revealing the shocking truth about your dual accounts. Why make two?

[Edited on 4-21-2014 by MrHomeScientist]

Brain&Force - 23-4-2014 at 14:53

I was not selected for the talent show. Oh well.

But we did have a leftover volumetric flask filled with methanol and copper chloride, and we ignited it. I made a short video which I won't be able to upload for a while, but here's a still from it:

<img src="http://i.imgur.com/b69MvRl.png" title="Might try it with boric acid next time." width=800>
the person in the photo is not me

The copper chloride did not color the flame at all! This is unusual because I've done this with the copper chloride and a large turquoise flame shot out. The difference here is that I put too much methanol in the flask - I don't know if this is related.

Quote: Originally posted by MrHomeScientist  

And Brain&Force, you just blew my mind revealing the shocking truth about your dual accounts. Why make two?


I was bored :) though I normally keep public school computers logged into the Töilet Plünger account, so it's also a safeguard, so I can keep using my other account in case someone decides to hack the other one for some reason.

[Edited on 23.4.2014 by Brain&Force]

Brain&Force - 25-4-2014 at 19:59

I may be able to participate in the talent show - I just have to cut down prep time and the actual demo time to 2.5 minutes. Cutting down the demo time shouldn't be a problem, but cutting down the prep and clean-up time is. I'm thinking that I need to store all of the necessary solutions in plastic water bottles before I perform. Afterwards store the waste in a volumetric flask or an Erlenmeyer with a cork to prevent any spills from occurring.

I figured out why the thunder flask may not have turned green - there was nowhere near the amount of copper chloride necessary in the flask. Normally, the copper complex with methanol is green, but the solution was blue because it was so dilute. I'll try this again with a sufficient amount of copper chloride. If that doesn't work (though it should) I'll settle for boric acid or some other coloring agents. (Strontium nitrate [insoluble in methanol] worked, but only colored a part of the flame. It was an interesting effect.)

Any other recommendations for coloring agents?

I've got a question for anyone willing to answer: are chloro complexes of transition metals more likely to form in acidic solution? I added an NaCl solution to one of CuCl2 and NiCl2 and got no color change! It may have been too dilute for complex formation though...

I just thought of another demo: dissolving aluminum in copper chloride. It's pretty unusual and a bit of a deviation from just "solutions A and B" demos.

I'm also trying to get the thunder flask demo certified for performance without breaching any fire codes. I don't really consider it an "open flame" when performed in a volumetric flask because the flame tends not to exit the flask after ignition. (The match, on the other hand, is one.) If performed in a 5 gallon water jug, however, the flame does exit, so it's probably not likely to be allowed.

Brain&Force - 14-5-2014 at 19:57

I've got a guaranteed spot in the talent show. I'm just doing the thunder flask demos on 3 scales: 1 L, 2 L, and 20 L. The 1 L flask will contain just methanol, the 2 L jar will contain methanol with lithium nitrate dissolved in it (for reference, lithium nitrate is EXTREMELY soluble in methanol) and the 20 L jug will contain trimethyl borate made in situ with methanol and boric acid.

I only have one problem now: I have tried to get a red explosion in the 2 L jar, but every time I try mixing the lithium nitrate solution in methanol with the air and igniting it, the flame doesn't cause a red explosion - instead the flask just fills with red flame that hovers in the flask for a few seconds. When I tried it again with trimethyl borate, it exploded in the same manner as a 1930s flash bulb. Does the drop in vaporized methanol due to the addition of lithium nitrate cause the flame to not propagate quickly enough?

I also have gotten a few total failures with the methanol and lithium nitrate - no ignition occurred, or only a weak flame was produced that lasted less than half a second.

Could it also be the geometry of the jar? It's similar to a Boston round, but it's clear.

I've discovered another interesting demo - lighting lithium nitrate dissolved in methanol in a beaker with a match produces a red flame. But if the flame lasts long enough, it will induce oxidation of the match and a plume of smoke and red fire will be emitted as the match is destroyed.

ScienceHideout - 18-5-2014 at 16:08

Traditionally I have always done this "20 L" thunder bottle demo using a 5 gallon plastic water jug and ethyl alcohol... It seems a lot safer this way.

Morgan - 18-5-2014 at 18:34

This one's pretty zippy.
https://www.youtube.com/watch?v=yYj0U9AMBZc

Brain&Force - 18-5-2014 at 21:50

I'm using methanol in a 5 gallon (I just refer to it as 20 L because I prefer metric). Methanol doesn't make the glass explode as in Morgan's video, but it does burn faster than ethanol or isopropanol (91%).

I tried it in a 3 L water bottle but with no explosion, just a slow flame.

Fantasma4500 - 1-8-2014 at 03:24

'water into red wine'
NaCl and CuSO4 dissolved in water along with ascorbic acid, this is heated with minimum water
this is then crashed into cold water and then filtered, you should be able to just decant off the impurities a few times and be left with CuCl at the bottom, white ppt
this is then dissolved in NH4OH, and excess ascorbic acid is added until the deep blue solution turns nearly perfectly colourless

when acetylene is added (or.. CaC2) it will quickly turn red, supposing its because Cu2C2 is formed, this however doesnt have any explosive properties when you dump CaC2 into the solution

pure CuCl2 with ascorbic acid added should work too, or CuCl2 + HCl + Al, or boiling CuCl2 with HCl and copper pieces for a few hours

Brain&Force - 1-8-2014 at 13:10

I never seemed to tell anyone what became of this...

The theater director decided to kick me out because he didn't like open flames. Oh well. But this thread is still a good reference for whoever needs it later. I have a few videos of the different flames, which I'll upload to YouTube and link here.

MrHomeScientist - 1-8-2014 at 13:16

Geez. Such a shame to see schools' fear of chemistry or anything remotely risky. I assume you'd have a fire extinguisher nearby, which should be plenty safe enough. Colorful flames would make a neat video for sure. I tried making one a long time ago but never could get it right - the camera couldn't handle the sudden brightness and every color just looked white.

I actually just had a somewhat similar experience with a school. I wanted to do some thermite demos to finish a STEM camp I was teaching with a 'bang', and had to clear it with the campus safety people. Initially they were pretty concerned, understandably. I had to reiterate several times that it was not explosive at all, but eventually I got the point across and they allowed it. I think it helped that I was able to send him a link to one of my thermite videos, which showed him exactly what it was and demonstrated that I'd done this sort of thing before.
The kids loved it, and I broke up the iron and slag products to hand out as souveniers. The winning team for the week also received the coveted Melted Bucket trophy. (Forgetting to bring my metal pail with sand for the products to drop into, I used a plastic one with sand instead. The molten products never touched the pail itself, but the radiated heat was enough to melt the whole bucket above where the sand was filled to!)

[Edited on 8-1-2014 by MrHomeScientist]

Brain&Force - 1-8-2014 at 13:25

Unfortunately, the main problem is that the theater directors didn't bother to buy fire safety curtains and didn't have the money to buy them. (They did have fire extinguishers handy though, and I have my own if I needed to bring one.)

[edit] here's the video with trimethyl borate:

<iframe sandbox width="560" height="315" src="//www.youtube.com/embed/-_0GfkXgBGA" frameborder="0" allowfullscreen></iframe>

[Edited on 1.8.2014 by Brain&Force]