DrP

Yea - some synthetics can be made harder than diamond now. Some guy I knew made a substance during a project he was on at uni in France. He reckons the hardness was above diamond. Can't remember what it was though - think that might have been some boride as well.

The compounds which oxidise the noble gasses mainly contain Fluorine iirc. XenonFluride (XeF6)is a good example of a possible xenon compound.......and guess what?? It's the fluorine doing the oxidising! Woelen posted about Na4XeO6.8H2O being a really strong oxidizer - this is probably due to the fact that the Xe is so weak at keeping it's oxygen that it readily gives it up (it's stable enough without it anyway).

Upsidedown pizza sounds great! It leads me to a question though! Why is it that people consider pizza to be unhealthy? We have: Bread Base (V. Healthy) Tomatoes (V. Healthy) Onions (Healthy) Cheese (Dairy product, contains fat, but so what - Healthy food) Toppings (other vegetables and mushrooms [Healthy] and meat [also required in a non veggie diet, so healthy]) So why is it that when all of these perfectly healthy ingredients are put together to make a mouth watering pizza - it is considered an unhealthy food option by some? ..... SO - here's my healthy option recipe: Pizza! AND - accompany said pizza with a nice large glass of red wine for extra health benefits!

We had something similar here, if you haven't voted already: http://www.scienceforums.net/forum/showthread.php?t=34540&highlight=election

To add to this (I once had to write a leaflet in English for an Indian man who sold these solar powered water heating units) - the copper pipe should be 'squashed' so that instead of a circular x-section you have a flat elipse. Thus - more area at 90 degrees to the incident rays - also - more internal suface area for the transfer of heat to the water from the pipe. - And yes - paint it matt black. You want the piping to be as long as possible over the solar pannel - snaking the whole length, and yes the the pannel should also be metal, black and have as much of it's area in contact with the piping (so any energy it absorbs can also be transfered to the pipes also).

Ah well, what your forgetting is that we have genetically engineered this horse you see, so that its waste gets stored in a marsupial like sack just benieth it's behind - it gets stored there for emptying upon landing. Anyway - if you did happen to get some spillage, then the effects of impact would be umplesent, but probably not fatal. Also - there would be no need to fly at 5,000 feet - you could stick to a couple of hundered feet.

OK - that last one was a HPLC pump apparently.

Well if we are talking 'what if' technology, then i suppose we could genetically engineer a horse/eagle hybrid to create some kind of pegasus type beast. They'd be enviromentally freindly and much safer than a flying car. How cool would they be? .

. Well why not? Well that's pretty much it: Covailent - sharing of electrons through the bond with overlapping orbitals Ionic - Strong attraction between highly positive and negaive atoms. Hydrogen - weak attraction between partially positive and negative areas on a molecule. Depends on your text book and what level of detail you wish to know about. When begining chemistry, you usually get tought things as being far simpler than they actually are. As as your understanding grows and you qualify further and further you get introduced to more complicated and advanced models which better explain in more detail what actually happens. Each year as you go through your education in chemistry you learn more complex models to replace the old ones you learnt. Example - it's important to under stand the basics of positive negative attraction between charges and the importance of an atom filling up its outer shell of electrons to become stable, before learning about bonding (because bonding is about getting the atom into a more stable state by filling up shells of electrons to balance charges) -- it get more complicated than that - but you learn the basic need first, otherwise you wont understand the later theorys.

Schottky & Bader (AT&T BELL) - The transistor? - is the first thing that comes to mind.

What about 4? - Obama will win by the seat of his hanging chad.

Sorry - forgot you were talking about Bi specifically rather than diamagnetism in general. The paramagnetic effect is ment to be stronger - I see your point - I've never actually thought about it. I can't find anything whilst briefly searching around, but the electron thing does seem to make sense. Let us know if you find out!!

Not at all - sorry if I missed your point. Pioneers post goes into more detail, beyond that of what you need to learn for school or for a basic understanding - interesting though.

Yea - it's the standard practical demo with the magnet next to the running tap pushing the water stream away. So nothing, iirc, to do with crystal stucture.

hmm - what about water though.

We can look at the stars and see them move across the sky - as we can with the sun. The motion of the stars suggests that we are moving as well as them. wrt the pendulum - as I mentioned before - we had one set up swinging over a hemispherical map in our physics foyer. This was constantly in opperation (ahem.. when it was actually working) and had a little battery at the top of the wire which gave teh pendulum a little extra push occasionally so it wouldn't slow down.

I'm with Obilix here - he asked about experiments to show the earths rotation - like the classic swinging pendulum expt. (we had that one set up and running perminantly in the foyer of our physics dept. at uni). I don't think he ever claimed anything about the earth NOT rotating at all. He just asked how you can prove it does (with classic expts like the swinging pendulum). I'm confused now..

Fair enough, but so what?, I still don't see how this creates any confusion as to what the differences are between covailent bonds and H-bonds. One being an actualy chemical bond with electron sharing and the other being an electrostatic attraction between 2 molecules with dipolar moments. I think that they are pretty well understood.

Well that's kinda my point (which I didn't explain to well in post #12) - I reckon that if you worked out how many balloons would give this pressure then you would need more than calculated due to the packing of the balloons as they stack. (If some jam against the edges of the cylinder and make an arch or bidge like structure - protecting those below from new pressures being added from above - these structure could repeat several times as the volume of balloons grows, starting teh stack anew each time) Just a thought - this could be rubbish. Does anyone know what I am talking about here or am I barking up the wrong tree - i.e. would this happen at all?

I thought it was pretty clear cut really. A H-bond is a dipolar attraction between delta- and delta+ areas between molecules. A Covailent bond is the actual overlapping of shells to share electrons across a bond. Very different and is well understood and defined - What is it that we are still researching aspects of then npts?? We we taught about H-bonding quite early in chemistry lessons.

wise man say: "Tree that's buffeted by wind grows strong. Is last one standing when hurricane come".

My thoughts and speculations: Say we did this experiment inside a huge cylinder - say 5 to 10 meters across and very high. I stand in the middle at the bottom of the cylinder and the balloons start to rain in from the top of the cylinder. As they stack arround me and over me and start to build up and fill the cylinder, not all of there mass will be causing a pressure straight down on me. Depending on the way thay stack - the forces will be distributed and dispersed around me as the balloons stack and form a structure in themselves. Some of the weight will be directed into the walls of the cylinder..... I don't think I am explaining this very well - but imagine an avalanche..... You can be trapped under alot of snow without being crushed as the the snow makes a structure of compact composite out of itself and shields you from more weight. I reckon this would happen with the balloons too. (?)

I Think that 'heat rises' normally means through convection - which obviously wont happen in a vacuum. Heat transfer by radiation and conduction through contact would be the only mechanisms which would work in a vacuum. I don't think they are effected by orrientation (up and down) rather than from path of least resistance from hot to cold and radiation in a straight line. I would say no based on the energy transfer here being radiated and conducted alone - no convection inside the bulb. There would be convected heat from the bulb, which would go upwards of course, but in the vacuum of the bulb I can't see how orientation would effect the heating of the casing or base one way or the other.

I'm not a biologist so someone else can reply. But the first things that spring to mind are rates of decay and growth. This was always the example given to us as 'maths in biology'. These days I wouls guess that drug delivery systems need a bit of math (as they are more chemistry/physics really) - rates of transport through membraines and stuff. ?