Thursday, January 29, 2009

Negative Pressure : a Critical Invention.

Negative Pressure : a Critical Invention.
Andre Willers
29 Jan 2009

Source :
NewScientist 13 Sept 2008 p26 " Making the most of trees pulling power"

Synopsis :
Negative pressure joins negative refraction index and negative Kelvin temperature as
useful constructs .
The presence of negative pressure in trees makes one wonder whether the other two items might not also be found in nature .

Discussion :
Ever wonder why trees can be so tall ?
Capillary action only works up to 10 meters height .

The reason :
Leaves have nano-pores that allow only water molecules to pass , but not air .
The hydrogen-bonds in water form a linked chain from the leaf to the root .
As the water molecule is pulled out at the leaf-pore , it tugs on the whole chain .
This is expressed as negative pressure .

The Trick .
The hydrogel material used in soft contact lenses has the right size nano-pores to allow water molecules to pass , but not air . Just like leaves of a plant .

Synthetic trees:
Using this material , Abraham Stroock of Cornell University constructed artificial trees with negative pressures of 10 atmospheres . (ie a 100 meter tree equivalent)

Some consequences :

1.What does this do to eyeballs with soft contact lenses ? Glaucoma?
Can the cornea be shaped by using fixed hydrogels ?

2. Powerful nano- and micro pumps .
Nano-tech .
Phase-change medicine delivery systems . Concentration variation .
A lot of micro-pumps together = macro pump . (Our old friend the tree)

3. Cosmetics.
There seems to be some promise for cosmetic procedures involving pumping out surplus fluid from cells by dabbing on hydrogels .
Argh! Those cucumbers slices on the eyes might work after all !
See "Cool as a cucumber"

3. Chemo therapy
Killing targeted cells by dehydration .
Cancer cells by definition must use more water than normal cells . So hit them with the water bill . Or better yet , a prepaid meter .

4. Food preparation and preservation .
Instant biltong .

5. Construction .
Concrete curing can be accelerated . Significant time-savings are possible .And time is money .

6. Desalinization = detoxification .
Removing the pure water out of a poisonous soup using only a hydrogel and a wind or fan seems to hold a powerful promise . A true cheap nanotechnology.

7. What will happen if you line a stomach with hydrogels ? Maybe intestinal bacteria are already doing the equivalent .

8. What will happen if you line alveoli in the lungs with hydrogel aerosols ? Emphysema , asthma .

9. Stealth propulsion .
Probably already used by oceanic slimy creatures . Tentacles coated by hydrogels with suitable hydrophilic and hydrophobic additions will dramatically increase silent propulsion efficiency .

10. Cavitation nullification in marine propellers .
Coating a propeller in hydrogel should dramatically increase propulsion efficiency and reduce noise and cavitation . An obvious money-spinner .

11. Terraforming .
See "Cool as a cucumber"
This is already part of the Earth's terraforming process .
Pseudonomas syringae is only one of the bacteria that uses nano-systems like hydrogels to influence the water concentration and by implication the remainder of gas concentrations of the planetary ecosystem .
What happens to the gases dissolved in droplets of water when they freeze ?

12. Paper
See "Paper"
Felt can be dispensed with , enabling much finer cellulose fibres . Benefits as discussed.

14. 3D Printing .
See "Beads"
Nano-printing becomes easier , as nearly any material can be suspended in water , printed via an Ink-jet type 3D printer , then dehydrated using hydrogels and then fixated .

As you can see , it goes on and on .

Cheap , precisely controlled variation of water concentrations is really important to water-based life-forms .

This is why this is a critical finding and invention .

Happy hunting!


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