Improving A Homebrew CT Scanner With Barium

CTscanner

[Peter] has been working on his homebrew CT scanner for a while, and it’s finally become something more than a spinning torus of plywood. He’s managed to image the inside of a few pieces of produce using an off-the-shelf radiation detector and a radioactive barium source

When we last saw [Peter]‘s CT scanner, he had finished the mechanical and electronic part of the Stargate-like device, but the radioactive source was still out of reach. He had initially planned on using either cadmium 109 or barium 133. Both of these presented a few problems for the CT scanner.

The sensor [Peter] is a silicon photodiode high energy particle detector from Radiation Watch this detector was calibrated for cesium with a detection threshold of around 80keV. This just wasn’t sensitive enough to detect 22keV emissions from Cd109, but a small add-on board to the sensor can recalibrate the threshold of the sensor down to the noise floor.

Still, cadmium 109 just wasn’t giving [Peter] the results he wanted, resulting in a switch to barium 133. This was a much hotter source (but still negligible in the grand scheme of radioactivity) that allowed for a much better signal to noise ratio and shorter scans.

With a good source, [Peter] started to acquire some data on the internals of some fruit around his house. It’s still a slow process with very low resolution – the avocado in the pic above has 5mm resolution with an acquisition time of over an hour – but the whole thing works, imaging the internal structure of a bell pepper surprisingly well.

Researchers Create Synthetic Muscle 100 Times Stronger Than the Real Thing

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A team of researchers at the University of Texas at Dallas have come up with an ingenious way to make a low-cost, high strength, artificial muscle. Their secret? Fishing line. The study was just published today in the journal Science, and the best part is they describe how to recreate it at home.

To create it, the researchers take regular fishing line (polyethylene or nylon string) and twist it under tension until it curls up into a tightly formed spring. It can then be temperature treated to lock in this position.

When heated again, the plastic tries to untwist — the peculiar thing is, this causes the entire coil to compress — think of it as Chinese finger-trap. Polyethylene and nylon molecules also contract lengthwise when heated. It can contract up to about 49%, with as much pulling power as 100 times its equivalent human muscle in weight. This equates to about 5.3 kilowatts of mechanical work per kilogram of muscle weight — similar to the output of a jet engine.

Stick around to see the video of how to make it — we’re excited to see what you guys think up for project applications!

[Read more...]

Cleaning Slides with Plasma

Plasma Cleaner

[Ben Krasnow] hacked together a method of cleaning sides using plasma. His setup uses a mechanical vacuum pump to evacuate a bell jar. This bell jar is wrapped with a copper coil, which is connected to an RF transmitter. By transmitting RF into the coil, plasma is created inside the bell jar.

Plasma cleaning is used extensively in the semiconductor industry. Depending on the gas used, it can have different cleaning effects. For example, an oxygen rich environment is very effective at breaking down organic bonds and removing hydrocarbons. It is used after manual cleaning to ensure that all impurities in the solvents used for cleaning are fully removed. According to [Ben], it’s possible to get a surface atomically clean using this process, and even remove the substrate if the energy levels are too high.

These machines are usually expensive and specialized, but [Ben] managed to cook one up on his bench. After the break, check out a video walk through of [Ben]‘s plasma cleaner

[Read more...]

Retrotechtacular: Films Used to Be Recorded on Film

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We’re sure that this title makes some readers itch because there are still a number of well-respected directors who insist on shooting with film rather than digital, but the subject of this week’s Retrotechtacular shows a portion of the movie industry that has surely been relegated to life-support in the past few decades. Photo finishing, once the stronghold of chemical processes used by all to develop their photographs, has become virtually non-existent. This is the story of how film and photo finishing drove cinema for much of its life.

The reels seen above are negative and positive film. The negative film goes in the camera and captures the images. After developing and fixing the negative film, the process is repeated. Light shines through the fixed negative in order to expose a fresh reel of film. That film is finished and fixed to create the reel which can be used in a projector. This simple process is covered near the beginning of the clip found below. The 1940 presentation moves on to discuss the in-depth chemistry techniques used in the process. But you’re really in for a treat starting about half-way through when the old manual methods are shown, which have been replaced by the “modern laboratory”. We love those huge analog dials! The video concludes by showing the true industrialization of the film developing process.

We’re running out of Retrotechtacular topics. If you know of something that might be worth a feature please send in a tip!

[Read more...]

Machine Learning Used to Create an HIV Vaccine

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When we think of machine learning it’s usually in the context of robotics—giving an algorithm a large set of input data in order to train it for a certain task like navigation or understanding your handwriting. But it turns out you can also train a nasty virus to go to sleep and never wake up again. That’s exactly what the Immunity Project has been doing. They believe that they have a viable HIV vaccine and are trying to raise about $25 million to begin human testing.

The vaccine hacks the Human Immunodeficiency Virus itself, forcing it to mutate into a dormant form that will not attack its human carrier. It sounds so simple, but a lot of existing knowledge and procedures, as well as new technology, went into getting this far. Last week we spoke with [Reid Rubsamen, M.D.] about the process, which began by collecting blood samples from a wide range of “Controllers“. Controllers are people who carry HIV but manage to suppress the virus’s progression to AIDS. How do you find these people? That’s another story which Scientific American covered (PDF); the short answer is that thanks to the work of [Bruce D. Walker, M.D.] there was already a database of Controllers available.

The information accumulated by [Walker] then underwent a data crunching exercise. The data set was so enormous that a novel approach was adopted. For the laymen this is described as a spam filter: using computers to look at large sets of email to develop a complex process for sifting real messages out of the noise. The task at hand is to look at the genotype of a Controller and compare it with the epitope— a short chain of proteins—in the virus they carry. The power of machine learning managed to whittle down all the data to a list of the  first six epitopes that have the desired dormant-mutation property. The vaccine consists of a cocktail of these epitopes. It does, however, require some clever delivery tactics to reach the parts of the world where it’s most needed. The vaccine must not require refrigeration nor any special skills to administer.

The vaccine’s production uses existing methods to synthesize the amino acid peptides, which are the epitopes themselves. The packaging, however, is a new concept. [Dr. Rubsamen's] company, Flow Parma, Inc., is using microspheres to encapsulate the vaccine, which render it shelf-stable and allow it to be administered through a nasal spray. Learn more about the technology behind the production of microspheres from this white paper (PDF).

If the vaccine (which will be produced without profit) passes clinical trials, it could see mass distribution as early as 2017.

The $25M we mentioned earlier is a tall hill to climb, but think of the reward if the vaccine is successful. You can donate directly to help reach this goal. If you’re planning on giving gift cards this year, you can purchase them for many different retailers through Gyft, who is donating 100% of December proceeds to the project.

Boil Off Some White Gas in the Back Yard

Gas-still

[S Heath] is a Coleman lantern collector. Coleman lanterns can run from a variety of fuels, however they seem to run best with white gas, or Coleman fuel. Store bought Coleman fuel can cost upwards of $10USD/gallon. To keep the prices down, [S Heath] has created a still in his back yard to purify pump gas. We just want to take a second to say that this is not only one of those hacks that we wouldn’t want you to try at home, it’s also one that we wouldn’t try at home ourselves. Heating gasoline up past 120 degrees Celsius in a (mostly) closed container sounds like a recipe for disaster. [S Heath] has pulled it off though.

The still is a relatively standard setup. An electric hot plate is used to heat a metal tank. A column filled with broken glass (increased surface area for reflux) rises out of the tank. The vaporized liquid that does make it to the top of the column travels through a condenser – a pipe cooled with a water jacket. The purified gas then drips out for collection. The heart the system is a PID controller. A K-type thermocouple enters the still at the top of the reflux column. This thermocouple gives feedback to a PID controller at the Still’s control panel. The controller keeps the system at a set temperature, ensuring consistent operation. From 4000 mL of ethanol free pump gas, [S Heath] was able to generate 3100 mL of purified gas, and 500 mL of useless “dregs”. The missing 400 mL is mostly butane dissolved in the pump gas, which is expelled as fumes during the distillation process.

[Read more...]

The “Melt-O-Matic” – A Digital Melting Point Apparatus

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A common technique in organic chemistry is to determine the melting point of a specimen. While commercial options exist, [kymyst] decided to build one with similar (or better) functionality, and managed to keep it under $100. The basis of his rig is a 60W soldering iron. He simply replaced the normal soldering tip with an aluminum heating block that holds the capillary tubes and temperature probe. Two small fans are used to quickly cool the heating block, allowing fairly quick measurement times. It should be noted that building a project like this one will mean working with wires that carry 220V (or 115V, depending on your country). Please use proper precautions.

In case organic chemistry is on your list of ‘to learns’, [kymyst] included a nice writeup of the determination of melting points. It’s a great primer for those interested in learning more.

Using this setup, [kymyst] gets readings of ±0.1 °C. He mentions the possibility of adding a webcam for determining melting point automatically, something that would make this system competitive with much more expensive hardware.

The last time we saw one of these it used a hot glue gun as the heating element.

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