October 29, 2008

On cancer warnings and MIDI-making

Posted: 12:00 PM ET

Have you ever seen a small label on electronic devices, glassware, or other products that warns you about chemicals known to the state of California to cause cancer and reproductive harm?

A warning label says you should wash your hands after using this MIDI device, but the company says don't worry.

I recently discovered this warning on my MIDI interface, a small device that has cables connecting my keyboard to my laptop so I can record and edit the music that I play.

(Side note: MIDI stands for Musical Instrument Digital Interface, and refers to the protocol that allows instruments and computers to communicate. If you own a computer and a musical keyboard, I highly recommend you try connecting them and playing with a program such as Apple's GarageBand. The program, coupled with the keyboard, allows your keyboard to take on the sounds of dozens of instruments, from "orchestral strings" to "Fiji afterglow.")

Great, but I didn't want playing "Falling Slowly" using "tula bass" sounds to give me cancer. So, I called the maker of the MIDI interface device, and found out that the warning is required by California law for products sold in California that contain more than a minimum amount of particular substances, such as lead. But, according to the company, M-Audio, I shouldn't worry about getting toxic chemicals on my hands.

What's inside a product with a warning label? Read more on "Paging Dr. Gupta."

–Elizabeth Landau, Health Writer/Producer,

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Filed under: computers • Materials

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September 19, 2008

Concrete Solutions

Posted: 12:13 PM ET

Hard, flat, tough, solid. These are all words that you could use to describe concrete. But green? That’s not usually an adjective many people would apply to cement – unless, of course, they knocked over a can of emerald paint on their driveway… But here’s a rundown of some new environmentally friendly products that are paving the way to greener, well, pavement.

Workers lay Filtercrete (left) and Flexi-Pave (right) instead of regular concrete. Source: CNN/KBI

Recently used to green Chicago’s alleys (watch story here), Filtercrete is one of a few products that help improve normal pavement by making it porous. It is filled with tiny holes that allow water and air to flow between the surface and the soil. This reduces the runoff to local waterways, while increasing water input to local underground aquifers. Because water is less likely to be trapped in the porous concrete, there is a reduction in cracks caused by water freezing to ice. Filtercrete’s holes also harbor bacteria that break down contaminants like oil and grease, so water is cleaned as it passes into the ground.

Flexi-Pave: KB Industries’ flagship product Flexi-Pave adds one more green aspect to porous pavement. Used for ‘low-speed’ surfaces like sidewalks, trails, and parking lots, Flexi-Pave is made primarily of recycled tires. Considering they are used at a rate of one per person per year, there are a lot of worn-out rubber tires out there that could be diverted from landfills and recycled into pavement.

Because it’s made of rubber, Filterpave can expand with any freezing water that happens to be caught in the product’s pores, further reducing the chance of cracking. Also, the product can be outfitted with subsurface heated water pipes to help melt snow lying on the pavement’s surface. “[It] causes any snow to immediately turn to water and pass through the product,” says Chief Operating Officer Trey Wylie, “[Clients] have eliminated snow removal costs and no longer have to apply chemicals throughout the winter.”

Air-Purifying Concrete: It’s still in the research stage, but scientists at the University of Twente in the Netherlands are developing a form of concrete that could help clear nitrogen oxides from the air. Nitrogen oxides are those chemicals that cause problems like smog and acid rain, but this new concrete will contain a chemical – titanium dioxide – that converts nitrogen oxides into harmless nitrate salts.

The salts are rinsed off the surface and into drainage systems when it rains, and the concrete should continue to perform over time. “[Titanium dioxide] is a catalyst, so it is enabling the reaction, but not participating, not consumed, so it never wears out,” says researcher Jos Brouwers. He adds that the air-purifying concrete could potentially be combined with porous concrete products like those mentioned above or even used in decorative facades of buildings. Results on how effectively the concrete performs in field tests are expected in 2009.

So what do you think of these products? Where can green pavement go from here?

Julia Griffin, CNN Science & Technology

Filed under: Cars • environment • Materials • recycling • Tires

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April 3, 2008

Solving a Sticky Problem

Posted: 12:14 PM ET

It seems there's virtually no dilemma plaguing humanity that hasn't been studied by some scientist, somewhere.

A torn poster in Serbia-Montenegro illustrates the "wallpaper problem." Source: DIMITAR DILKOFF/AFP/Getty Images

Case in point: You know how, when you try to tear down old wallpaper, or pull a label off something, it invariably peels on a diagonal line instead of coming off straight, so you end up with a point still stuck to the surface?

Well, apparently that really bothered a team of scientists from MIT, the Centre National de la Recherche Scientifique in Paris, and the Universidad de Santiago, Chile.

"This shape is really robust, so there must be something fundamental going on that gives rise to these shapes," said Pedro Reis, a mathematics instructor at MIT.

Now, the researchers have explained the physics of what they call "the wallpaper problem," according to a press release from MIT.

The team analyzed how the stiffness and toughness of a material being pulled off a surface interacts with the strength of the adhesive holding it in place.

The scientists say energy builds up along the line where the strip of wallpaper (or whatever) is peeling from the wall, and one way for the energy to be released is for the strip to become narrower – so it does.

The team also came up with a way to predict the angle at which a given piece of wallpaper will tear.

The scientists say the same thing happens when you peel a tomato or a grape. It's not clear whether any of the researchers actually sat around peeling grapes.

The research could actually have practical applications in industries where the properties of sticky films are important.

The study was published in the journal "Nature Materials."

–Kate King, Writer,

Filed under: Materials • Physics

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