'Smart’ windows could save energy

Tiny droplets sandwiched between glass panes turn cloudy when it’s hot outside; this filter out some warming sunlight.

 

 
Sunlight streaming through a window can really heat up a room. In winter, when heating bills can soar, people tend to welcome that extra warmth. But in summer, that heat just boosts cooling costs. A homeowner could keep out some of that warming light by drawing the curtains or lowering the blinds. Or the window could change its transparency — blocking out some light, as needed — all by itself. That’s the idea behind new “smart” windows.

Some smart windows already exist. They work just like large versions of the LCDs (liquid crystal diodes) found in watches and other electronic devices. When an electric current flows through an LCD window, a coating on the panes of its glass darken. That blocks out some of the light. A homeowner can control the window’s light-blocking ability — or opacity — simply by flipping a switch. Or, a sensor connected to the window can automatically control the current, just like the thermostat used to control a furnace or air conditioner.

But the new smart window does not require such electronics. It depends only on the temperature outdoors, says Xuhong Guo. He’s a chemical engineer at the East China University of Science and Technology in Shanghai. His team designed a new liquid that it sandwiches between two panes of window glass. The researchers describe how this makes their window “smart” in the December 3 issue of Industrial & Engineering Chemistry Research.

The key: A heat sensitive gel

The material that Guo’s team designed is a colloid. That’s a substance in which tiny particles or droplets that don’t dissolve are spread throughout a larger volume of some other material. (Smoky air is one type of colloid. Milk is another.) The larger part of the new mix is a blend of water and alcohol. Floating inside are tiny globs of a gel.

Each glob is only between 200 and 700 nanometers across. That makes the diameter of the thinnest human hair about 24 to 85 times wider than each glob. The gel contains a heat-sensitive polymer (a chemical made from chain-shaped molecules). It also contains water and glycerol, a type of alcohol. The water and glycerol attach loosely to the polymer. This keeps the gel from dissolving into the larger volume of liquid. This also ensures that the gel globs don’t react with each other to form one big lump of goo.

Rewritable paper: Prints with light, not ink

A new paper design could eliminate tons of landfill waste.

 

 

A new type of paper can be used and reused up to 20 times. What’s more, it doesn’t require any ink. Its designers think that this new technology could cut down on tons of waste — and save people tons of money.
A special dye embedded in the paper makes it printable and rewritable. The dye goes from dark to clear and back when chemical reactions move electrons around. (Electrons are the subatomic particles that orbit in the outer regions of an atom.) The paper’s color-change chemical undergoes what are known as redox reactions. Redox is short for reduction and oxidation.
Oxidation steals one or more electrons from a molecule. Rust is an example of oxidation. “When iron rusts in air, its electrons move to nearby oxygen atoms,” explains Yadong Yin. He’s a chemist at the University of California, Riverside.

Reduction is the opposite of oxidation. It adds one or more electrons. As rust oxidizes iron, the process reduces those nearby oxygen atoms. That means that they gain electrons, which have a negative charge.

When dye in the new paper is oxidized, it appears blue, red or green. (What color depends on which dye is in the paper.) When the dye on some parts is reduced, color on those areas disappears. Controlling these two reactions makes it possible to print on, erase and reuse the new paper.

The starting base of the “paper” used in the study was a clear plastic. That allowed it to show how the paper works. But the technology also could be used with glass or conventional paper — the type made from wood pulp — as long as each contains the redox dyes and the other chemically active components.

How it works

The paper starts out with all of the dye oxidized, and therefore colored. Nano-scale crystals of titanium dioxide — each around a billionth-of-a-meter in size — cover the paper’s surface.

Seven ways that chemistry puts the magic into Christmas

From the enticing aroma of the turkey in the oven to the “whoosh’” of the flames as the brandy-soaked pudding comes alight, Christmas is a wonderful time for the senses. But have you ever considered the science behind our best-loved festive traditions? Here are seven of my food and flammable favourites:

Candle light, shining bright

 

Candle-lit carol services are part of Christmas for many people, as are the ones entwined in holly on the table. Traditionally beeswax was used but while it gives great flames, it is rather expensive. Nowadays the vast majority of candles are made of paraffin wax obtained as one of the products of oil refining. These waxes are hydrocarbons, molecules made of two different elements: carbon and hydrogen.

When you light a candle, wax is melted, and the molten wax gets drawn up the wick, which gives a larger area for the wax to evaporate. It is the gaseous wax that burns, forming carbon dioxide and water, and giving out energy, which is where the heat and light come from.

But not all the carbon atoms get turned into carbon dioxide at one go – it is carbon-rich soot particles glowing hot that give out the yellow light that characterises a candle flame.

Turkey time

Most people know that cooking involves chemistry, and where better to start than the Christmas Day turkey? The turkey meat you cook is muscle tissue, about 20% of which is protein (nearly all the rest is water), with a small but important amount of carbohydrate. If you “hang” the meat and allow it to age, enzyme catalysts naturally present in the muscle start to break down the proteins so that they lose their naturally rigid structure and the meat becomes more tender.

Bubbles, Bubbles Everywhere!

Bubbles are scientific?

That was the question I had when I first realized there was a Bubbles show at Science World at TELUS World of Science. Then, after watching the show and learning more about bubbles leading up to doing my own first Bubbles show performance, I learned that there is actually a lot of science and math involved. Even more, there’s a special chemistry and geometry when it comes to making bubbles.

What's bubble chemistry?

 

Well, bubbles are more than just a soap solution filled with air. Bubbles are actually made from a bubble film that looks like a sandwich with soap on the outsides and water on the inside. The soap works to reduce the surface tension of water so that the water can stretch. This means that bubble film is elastic and stretches out and snaps back to its original shape.

 

 
Why are bubbles round?
This is where the math comes in. Forming a bubble takes energy and bubbles want to form a shape that is the least stretched out. This shape must have the least amount of surface area for its size. The shape that results is a sphere. This is why bubbles are round when they are floating through the air around us!

Chemistry: Green and clean

Chemists are finding ways to save energy, cut waste and boost safety.

People have used chemistry to improve their lives for tens of thousands of years. An early example: fire. Our prehistoric ancestors tamed flames to transform plants and animal products — that is, to cook them into food. Over time, their descendants learned about the chemical properties of rocks and other minerals, and of chemicals derived from plants and animals. They mixed materials together. Sometimes, they also applied heat, pressure or both. Through trial and error, they learned how to make new and useful materials. Paints and soap are two notable early examples.

Today, chemistry plays a role in almost every product imaginable. Manufacturing companies have registered more than 83,000 chemicals with the U.S. government. Many of these find use in everything from foods and plastics to trucks and electronics.

Making, using and disposing of these chemicals, however, can pose risks to people or wildlife. Some chemicals, after all, are made from toxic raw materials, such as mercury or lead. Making other chemicals requires huge amounts of energy, clean water or other natural resources. And as we use them or discard them as trash, many chemicals can pollute the air, water or soil.

In the early 1990s, chemist Paul Anastas called for a change. While working for the U.S. Environmental Protection Agency, or EPA, he recognized that chemists usually probe possible risks of chemicals long after they have developed them. Anastas urged his fellow chemists instead to design products that would be safer and cleaner from the start.

The color green is often associated with anything that is good for the environment. So Anastas called this new field “green chemistry.” (It’s also sometimes called sustainable chemistry.)

X-rays shine light on atoms at work in a chemical reaction

For more than 100 years, scientists have “peered” at atoms in a crystal by analysing the way they scatter X-rays. This process, known as crystallography, reveals the chemical structure of compounds in the crystal and has applications so wide-ranging – from drugs to new materials – that it has become central to how science is done.

But almost all of these advances have depended on revealing the chemical structure of unchanging compounds. However, if Makoto Fujita at the University of Tokyo and his colleagues are proved correct, this may all change. For they have developed a method to capture “images” as chemical reactions happen. The difference is in someways as big as that when cameras went from capturing still images to shooting film.

Dark magic

At this very moment, there are billions of chemical reactions taking place in your body. And yet each of these chemical reaction is special, because for it to occur two or more molecules have come in close contact under the right conditions. These “right conditions” are mostly dependent on the energy available in the system. Without enough energy, the necessary movement of electrons will not occur and the reaction will fail.

In nature, the required amount of energy has always been a tricky thing to achieve. To overcome this situation, many biological reactions make use of a catalyst, which does not react with the substances but accelerates the reaction. For instance, your body contains small amounts of manganese, zinc, and copper that are all required as catalysts for key reactions in the body.

Mosquitoes, be gone!

Two teens find an extract from common seeds can kill mosquito larvae and also may repel the biting adult insects.

 

LOS ANGELES — Extracts from the seeds of a common plant can kill mosquito larvae, report two teen researchers. Smoke from a candle made with wax that includes the extracts also repels adult mosquitoes. The natural chemicals therefore show promise as an alternative to synthetic pesticides, the young scientists say.
The teens reported their findings here last week, at the Intel International Science and Engineering Fair, or Intel ISEF. The competition was created by Society for Science & the Public (which publishes Science News for Students) and is sponsored by Intel. Each year, Intel ISEF showcases some of the best high school science projects from around the globe.
Bixa orellana is a small tree or shrub found in many tropical regions in the Americas. Its bright red seeds already have many uses, says Ester Castro, 17. She’s an 11th-grader at Asuncion Rodriguez de Sala in Guayanilla, Puerto Rico. Extracts from the seeds are a popular food coloring, she notes. Powdered seeds also are part of spice mixtures used in cooking.

Ester and classmate Keren Galarza, 16, wanted to see if chemicals in the seeds might repel mosquitoes. The seeds contain many compounds. Some of the chemicals are smelly, oily substances that float on water. These are called “volatile oils” because they contain aromatic substances that evaporate easily. Others compounds are part of a thick, sticky substance called resin. The red substance used as a food coloring is called bixin, after the plant. The liquid that’s left behind when all of these substances are removed contains a yellow coloring, called orellina.

YOUNG SCIENTISTS: Better than plywood

Two teens made a strong, waterproof building material out of things that are normally thrown away.

Nurul Roslan (left) and Hanis Zaini (right), both 17, invented a new material from a blend of recycled plastic and pineapple leaf fibers. It’s waterproof and stronger than plywood, according to tests by these teens from Melaka, Malaysia.

 

LOS ANGELES — A new material made from plant leaves could be replace plywood for many uses. The material is strong, waterproof, cheap and easy to make. Two teens invented it using a blend of pineapple waste and recycled plastics.
Those raw ingredients are abundant in Malaysia, where the girls live. The largest part of the new material is a type of plastic called high-density polyethylene. It is used to make many things, including milk jugs and shampoo bottles. Known as HDPE, this plastic is often recycled or thrown away, says Nurul Roslan, 17. She attends Mara Junior Science College Terendak in Melaka, Malaysia. But when treated like trash, the plastic doesn’t degrade quickly. Studies show that this plastic can take about 450 years to break down, she says.

The other ingredient in the new material is fiber from pineapple leaves. These leaves are tough because they contain a strong material called lignin. It doesn’t decompose quickly. Farmers often burn the leaves to dispose of them. That causes air pollution, says Nurul’s classmate Hanis Zaini, who is also 17. If farmers don’t burn the leaves, they send them to a landfill. There they join the discarded plastic.

Science in Action Winner for 2013: Elif Bilgin

Elif Bilgin, winner of the 2013 Science in Action award, a $50,000 prize sponsored by Scientific American as part of the Google Science Fair. Credit: Elif Bilgin

“Genius,” Thomas Edison famously said, “is 1 percent inspiration and 99 percent perspiration.” He would have found a kindred spirit in Elif Bilgin, 16, of Istanbul, Turkey, winner of the 2013 $50,000 Science in Action award, part of the third annual Google Science Fair. The award honors a project that can make a practical difference by addressing an environmental, health or resources challenge; it should be innovative, easy to put into action and reproducible in other communities.

What makes rain smell so good?

A mixture of plant oils, bacterial spores and ozone is responsible for the powerful scent of fresh rain. Image via Wikimedia Commons/Juni

Step outside after the first storm after a dry spell and it invariably hits you: the sweet, fresh, powerfully evocative smell of fresh rain.

If you’ve ever noticed this mysterious scent and wondered what’s responsible for it, you’re not alone.

Back in 1964, a pair of Australian scientists (Isabel Joy Bear and R. G. Thomas) began the scientific study of rain’s aroma in earnest with an article in Nature titled “Nature of Agrillaceous Odor.” In it, they coined the term petrichor to help explain the phenomenon, combining a pair of Greek roots: petra (stone) and ichor (the blood of gods in ancient myth).