A Darker Shade of Black

With a reflective index of 0.045 per cent--the new standard for "dark" captures 99.955 of incident light. Darker darks and whiter whites are not just for laundry detergents, painters, and interior designers. The ability to control radiative energy is useful to scientists, engineers, and industrialists.

An ideal black object absorbs all the colours of light and reflects none of them. In theory, it should be possible to make something that approaches the "perfect absorber"...But it has proved difficult to construct an object that does not reflect light at all...Researchers at Rensselaer Polytechnic Institute in Troy, New York, turned to carbon nanotubes - structures made from carbon, billionths of a metre across, that have unique properties.

...A team led by Dr Pulickel Ajayan, who is presently at Rice University in Houston, Texas, built an array of vertically aligned, low-density carbon nanotubes. Dr Shawn Lin measured the optical properties....The roughness of the material's surface was tuned to minimise its optical reflectance....Experiments showed that this "forest" of carbon nanotubes was very good at absorbing light, and very poor at reflecting it.

Reporting their findings in the journal Nano Letters, Dr Ajayan, Dr Lin and colleagues say the reflectance of the material is three times lower than previously achieved.

BBC

Here is the key to the image above-- "uses of nanotech" (BBC):
1 - Organic Light Emitting Diodes (OLEDs) for displays
2 - Photovoltaic film that converts light into electricity
3 - Scratch-proof coated windows that clean themselves with UV
4 - Fabrics coated to resist stains and control temperature
5 - Intelligent clothing measures pulse and respiration
6 - Bucky-tubeframe is light but very strong
7 - Hip-joint made from biocompatible materials
8 - Nano-particle paint to prevent corrosion
9 - Thermo-chromic glass to regulate light
10 - Magnetic layers for compact data memory
11 - Carbon nanotube fuel cells to power electronics and vehicles
12 - Nano-engineered cochlear implant

Of course, those are only a very few of the uses of nanotech.

H/T Bayou Renaissance Man


This nanotube material absorbs well within visible wavelengths. What is needed is material that absorbs well across the entire electromagnetic spectrum. From X-rays to long wave radio. That would be a stealthy material.

It is still a very useful discovery--giving a way to capture almost all visible light will allow manipulating radiative energies in ways never before possible.

When Maxwell invented his famous "daemon", he did not anticipate the discoveries in nanotechnology that would allow humans to get down to the scale of atoms and molecules. Humans are looking for ways to cheat entropy.

Any sufficiently advanced technology becomes indistinguishable from magic--acording to Arthur C. Clarke. We are standing on the verge of sufficiently advanced technologies.

Harvesting Waste Heat: Nanowire Thermoelectrics

Silicon nanowires offer us yet another way to turn waste heat from heat engines into electric power. Silicon is less expensive than previously used bismuth and tellurium.

The thermoelectric effect occurs when one end of a material, such as a wire, is heated. Electrons travel to the colder end, producing an electrical current. However, to harness this energy effectively it is critical that the temperature difference is maintained. This requires a material with an unusual combination of properties - excellent electrical conductivity but poor heat conductivity. As silicon conducts heat well, no-one was expecting it to be a good candidate.

...James Heath of the California Institute of Technology led one of the teams. 'It was a surprise,' he told Chemistry World. 'We found that when you make extremely small silicon nanowires there are some fundamental differences in how these materials behave and transfer heat.'...Heath believes that with further research the efficiency of these materials could be boosted even further. The technology could help to cool and power microchips in the future, he added.

...Francis DiSalvo has worked extensively on thermoelectric materials at the Cornell Fuel Cell Institute, Cornell University, New York. 'This research is exciting but there is still some way to go,' he told Chemistry World...One important role for thermoelectric materials would be capturing heat that is lost during energy production by power stations or car engines, DiSalvo said. 'If these materials can be made cheaply enough, capturing even a fraction of this wasted heat would make them worthwhile,' he added.

ChemistryWorld

One reason nanowires are able to perform better than bulk materials is that thermoelectric efficiency is dependent upon "ZT", the thermoelectric figure of merit. A ZT of 1 or greater provides a higher thermoelectric conversion efficiency. T is temperature, but Z = S**2σ/κ, where S is the Seebeck coefficient, sigma is the electrical conductivity, and kappa is the thermal conductivity. It was recently discovered that in nanowires, the ratio of electrical and thermal conductivities can be better controlled in the higher, more favourable direction.

“Bulk silicon is a poor thermoelectric material at room temperature, but by substantially reducing the thermal conductivity of our silicon nanowires without significantly reducing electrical conductivity, we have obtained ZT values of 0.60 at room temperatures in wires that were approximately 50 nanometers in diameter,” said Yang. “By reducing the diameter of the wires in combination with optimized doping and roughness control, we should be able to obtain ZT values of 1.0 or higher at room temperature.”

...When scaled up, thermoelectric modules could eventually be used in co-generating power with gas or steam turbines.

Source

By capturing an ever increasing percentage of waste heat, society is able to "turn back entropy" somewhat.

Now we simply need to develop ways of "turning back the entropy" that has taken hold in educational systems, political systems, and nihilistic religions and philosophies.


H/T Brian Wang

Probing the Cell With Many Fingers

Eric Drexler talks about nanobots that roam the human body, looking for problems in cells--then jumping into the cell to repair any damage or dysfunction. Developing these "cell repair machines" will take some time. In the meantime, we need to learn different ways to probe the inner and outer workings of cells.

For example, we may want to develop a tiny nano-voltmeter to monitor the internal electric field of cells:

"The basic idea behind this field of research is to follow cellular processes---both normal and abnormal---by monitoring physical properties inside the cell. There's a long history of research on the chemistry happening inside the cell, but now we're getting interested in measuring the physical properties, because physical and chemical processes are related," said Kopelman, who is the Richard Smalley Distinguished University Professor of Chemistry, Physics and Applied Physics.

With a diameter of about 30 nanometers, the spherical device is 1,000-fold smaller than existing voltmeters, Kopelman said. It is a photonic instrument, meaning that it uses light to do its work, rather than the electrons that electronic devices employ.

Kopelman's former postdoctoral fellow Katherine Tyner, now at the U.S. Food and Drug Administration, used the nano-voltmeter to measure electric fields deep inside a cell---a feat that until now was impossible. Scientists have measured electric fields in the membranes that surround cells, but not in the interior, Kopelman said.

With the new approach, the researchers don't simply insert a single voltmeter; they're able to deploy thousands of voltmeters at once, spread throughout the cell. Each unit is a single nano-particle that contains voltage-sensitive dyes. When stimulated with blue light, the dyes emit red and green light, and the ratio of red to green corresponds to the strength of the electric field in the area of interest.

Eurekalert

Clever, no? Or perhaps researchers could use X-rays to take snapshots of the cell in action:

A research team led by Jue Chen, an associate professor of biological sciences, obtained a snapshot of the tiny protein gate complex that opens and closes pathways through the protective cellular membrane. The gates, operated by small protein machines that push them open and closed, bring nutrients into the cell and flush out waste.

The Purdue-led team was the first to achieve an image of the middle step of the process, capturing the molecular interactions as material passes through the membrane.

...The research team used X-ray crystallography to obtain a picture of a special protein, called an ABC transporter protein, as it moved material through the cellular membrane. The work was published in last week's issue of Nature.

Purdue

But there are many more approaches (many fingers) used to probe cells:

• Cryo-electron Tomography
  
• Optical Biosensors
• Nano-Interfaces in Microfluidics
• MEMS Devices
• NMR
• Impedance Spectroscopy
• By Computer
• Oncoprobe
• Scanning Electrode
• Patterned Substratum

Etc.

Lighting Your Future Life

Interactive lighting. More lumens for less power cost. A brighter world that costs less to light.

Below is a look at the magic crystal ball.

Hat tips to Impact Lab and Gizmodo.