A Simple Way to Detect the Deadly Microcystin-LR Algae-Producing Toxin in Our Drinking Water!

A Simple Way to Detect the Deadly Microcystin-LR Algae-Producing Toxin in Our Drinking Water!

Microcystin-LR (MC-LR) is a deadly carcinogenic toxin found in blue-green algae or cyanobacteria. Microcystin-LR even in very minute quantities is responsible for causing liver cancer. MC-LR and other similar substances are found to be prominent players in biological water pollution. The algae-producing toxin was the chief culprit for causing large scale poisoning in humans, centuries ago when wells, springs, and lakes were the main sources for drinking water. A group of scientists lead by Nicholas Kotov, a professor in the departments of chemical Engineering, Biomedical Engineering and Materials Science and Engineering at the University of Michigan discovered a simple method for testing the presence of MC-LR in drinking water.

The researchers found out that a strip of paper infused with carbon nanotubes could quickly and detect the MC-LR toxin produced by algae in drinking water. They found that the paper strips perform 28 times faster than the complicated method most commonly used today to detect microcystin-LR, (University of Michigan).

Water treatment plants, even in developed countries don’t always remove MC-LR completely according to Kotov. The safety of our drinking water is a vital issue in many developing countries and in many parts of the United States, He said.

There have been so many talks about the quality of our drinking water. So, whatever we can do to help the public stay safe from contracting diseases from drinking water is more than appreciated. This new technology for testing water can be used by cities and states to test drinking water quality on a regular basis. In addition, the technology can also be used to test for toxins in foods.

The technique works by measuring electrical conductivity of nanotubes in a special synthesized paper. Before the nanotubes are introduced into the paper, they are mixed with antibodies for the MC-LR toxin. So, when the paper comes in contact with water that is contaminated with the MC-LR toxin, those antibodies go between the nanotubes to bond with the MC-LR toxin, thus, causing the nanotubes to spread apart, (University of Michigan).

This spreading-apart of the nanotubes, cause a significant change to the nanotubes’ electrical conductivity. This electrical conductivity is measured by an external monitor, the researchers said. The result of testing water appears in about 12 minutes, (University of Michigan). Therefore, such rapid resulting can be beneficial to any city or state that wants to rule out a particular biological contaminant suspected in drinking water in very rapid fashion.

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Using Carbon Nanotubes To Produce Electricity

Using Carbon Nanotubes To Produce Electricity

The researchers of Massachusetts Institute of Technology (MIT) have uncovered a new phenomenon of carbon nanotubes. They found that carbon nanotubes discharge powerful waves of electricity under certain circumstances. MIT team named it as thermopower waves. They are pinning their hope on thermopower waves to produce electricity to be utilized in small electrical appliances or maybe in large-scale applications too. This project was funded by the Air Force Office of Scientific Research, and the US National Science Foundation (NSF).

This discharge of electricity from carbon nanotubes is a very rare occurrence. Traditionally we derive electricity from water, sun, wind, coal or heat produced by burning of fossil fuels. The thermopower wave, “opens up a new area of energy research, which is rare,” said Michael Stranowho is MIT’s Charles and Hilda Roddey associate professor of Chemical Engineering. His work was published in scientific journal Nature Materials.

Carbon nanotubes are submicroscopic structures. They are just billionths of a meter in diameter. Carbon nanotubes resemble honeycombs. For the past twenty years scientists are focusing their energies on carbon nanotubes, graphene sheets and buckeyballs. They find these three most promising for clean and green energy research. These three substances can be valuable for the medicine, nanotechnology, geoengineering, biology, and for the electronics industry.

Researchers associated with this project find the whole phenomenon quite unusual. They have observed that as the moving pulses of heat pass through the carbon naotubes, electrons also travel along. This movement of electrons is responsible for generation of electric current. Strano says, “There’s something else happening here. We call it electron entrainment since part of the current appears to scale with wave velocity.”

Researchers coated carbon nanotubes with a layer of reactive fuel that can generate heat by decomposing. This fuel was then ignited by a laser beam or high voltage spark at the one end of the nanotube. This ignition resulted in fast moving thermal waves. When this thermal wave enters into carbon nanotube its velocity increases thousand times than the fuel itself. When heat waves contact the thermal coating they produce a temperature of 3,000 kelvins. This ring of heat runs to the length of the tube 10,000 times faster than the normal spread of this chemical reaction. The unusual occurrence is that electrons also travel with the heat inside the tube. Strano says that events like this “have been studied mathematically for more than 100 years” but he was the first to envisage that such waves could be guided by a nanotube or nanowire and that this wave of heat could thrust an electrical current all along that wire.

Strano explains, “There’s something else happening here. We call it electron entrainment, since part of the current appears to scale with wave velocity.” He confirms that the thermal waves are behaving like ocean waves. We have observed that when ocean waves travel they carry the debris on their surface. Strano thinks that this property is responsible for the high power output by the system. Strano suggests the possible use of this discovery. He says that one possible use could be enabling new kinds of ultra-small electronic devices having sensors or treatment devices that would be injected into the body.

Ray Baughman, director of the Nanotech Institute at the University of Texas at Dallas, shares his views regarding the whole project that it “started with a seminal initial idea, which some might find crazy, and provided exciting experimental results, the discovery of new phenomena, deep theoretical understanding, and prospects for applications.” Because it revealed a previously unknown phenomenon, he says, it could open up “an exciting new area of investigation.”

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Nanoseries 1/5: What is a carbon nanotube?

What are carbon nanotubes? First episode of the nanoseries. Videos sponsored from WomenInNano, nano2hybrids and Vega Science Trust. www.nano2hybrids.net http Also available in spanish and french
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CNT has been prepared by fusing carbon rods at high temperature.

Charectization Of Carbon Nanotubes Based On Spectroscopic Techniques & Their Optical Properties

Charectization Of Carbon Nanotubes Based On Spectroscopic Techniques & Their Optical Properties

 

Charectization of carbon nanotubes based on spectroscopic techniques & their optical properties.

The optical properties of carbon nanotubes refers to the absorption, photoluminescence, and Raman spectroscopy of carbon nanotubes. Because spectroscopic techniques  allow quick and reliable characterization of “nanotube quality” in terms of non-tubular carbon content, structure (chirality) of the produced nanotubes, and structural defects. Those features determine nearly any other properties such as optical, mechanical, and electrical properties.

Carbon nanotubes are unique “one dimensional systems” which can be achieved by rolling graphene sheet.This rolling can be done at different angles and curvatures resulting in different nanotube properties. The diameter canvaries in the range 0.4–40 nm, but the length nanotube is about ~10,000 times reaching 4 cm. Thus the nanotube  have aspect ratio, (i.e  the length-to-diameter ratio) as high as 28,000,000:1,which is unequalled by any other material.As a result, all the properties of the carbon nanotubes relative to those of conventional semiconductors are extremely anisotropic and tunable.

 The tunability of properties is most useful in optics and photonics.

Carbon nanotubes are of three types

1.zig-zag

2.armchair

3.chiral

Following are the optical methods of charecterization ogf CNTs:

1. Optical absorption

Optical absorption in carbon nanotubes differs from absorption in conventional 3D materials by presence of sharp peaks (1D nanotubes) instead of an absorption threshold followed by an absorption increase (most 3D solids). Absorption in nanotubes originates from electronic transitions from the v2 to c2 (energy E22) or v1 to c1 (E11) levels, etc. The transitions are relatively sharp and can be used to identify nanotube types.

Interactions between nanotubes, such as bundling, broaden optical lines. While bundling strongly affects photoluminescence, it has much weaker effect on optical absorption and Raman scattering.

Optical absorption is routinely used to justify the  quality of the carbon nanotube powders. The spectrum is analyzed in terms of intensities of nanotube-related peaks, background and pi-carbon peak; the latter two mostly originate from non-nanotube carbon.
2.Carbon nanotubes as a black body

An ideal black body should have emissivity or absorbance of 1.0, which is difficult to attain in practice, especially in a wide spectral range. Vertically aligned “forests” of single-wall carbon nanotubes can have absorbances of 0.98–0.99 from the far-ultraviolet (200 nm) to far-infrared (200 μm) wavelengths. By coating Super black( a chemically etched nickel-phosphorus) the absorption of 1.0 can be achieved.

These SWNT forests (buckypaper) were grown by the super-growth CVD method to about 10 μm height. Two factors could contribute to strong light absorption by these structures: (i) a distribution of CNT chiralities resulted in various bandgaps for individual CNTs. Thus a compound material was formed with broadband absorption. (ii) Light might be trapped in those forests due to multiple reflections.

3.Luminescence

 

The Photoluminescence map of single-wall carbon nanotubes.  Can be help ful in identifying the nanotube semiconducting nanotubes with indices (n,m). The PL measurements do not detect other nanotubes with  indices n = m or mExcitation mechanism.Hence Photoluminescence (PL) is one of the important tools for nanotube characterization.

The excitation  mechnism of PL

 The excitation  mechnism of PL occurs as follows: an electron in a nanotube absorbs excitation light via S22 transition, creating an electron-hole pair (exciton). Both electron and hole rapidly relax (via phonon-assisted processes) from c2 to c1 and from v2 to v1 states, respectively. Then they

Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications (Topics in Applied Physics)

Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications (Topics in Applied Physics)

The carbon nanotubes field has evolved substantially since the publication of the bestseller Carbon Nanotubes: Synthesis, Structure, Properties and Applications . The present volume builds on the generic aspects of the aforementioned book, which emphasizes the fundamentals, with the new volume emphasizing areas that have grown rapidly since the first volume, guiding future directions where research is needed and highlighting applications. The volume also includes an emphasis on areas like graphe

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