“What’s your favorite color?” is a common question, particularly among children. However, there is a new color that might offer a partial solution to global warming by one day reducing the need for air conditioning (AC).

According to the Environmental Protection Agency, AC only causes a part of global greenhouse gas emissions. But that threat will continue to grow as temperatures rise with climate change, and people install (安装) more AC units. Facing this problem, researchers at Purdue University tried to replace the need for conditioning power and invented the world’s whitest paint. It is so white that it could efficiently reflect enough sunlight to cool off buildings.

In 2021, the researchers focused on two key parts of the white paint. The first is that the chemical mixture barium sulfate (BaSO3) can effectively reflect light. The second is that BaSO3 particles change in size allowing the paint to reflect more incoming light. The white paint reflects 98.1% of solar rays and sends out infrared heat (红外线热量) at the same time. Using highly accurate temperature-reading technology, researchers found that the paint kept surfaces 34.2­°C cooler, even during the hottest hours of the day.

The white paint can be a suitable choice to replace traditional AC. Air cooling power uses an about 5 kilowatts per 1000 square meter, but the researchers showed that their white paint could double that amount of power. If this innovation (革新) is applied to the outside of buildings, AC will be replaced with paint.

The team is optimistic about getting this paint into the market. They are working with a company at present. The white color can change the way people think about their cooling systems. Instead of installing large AC units that already use a lot of electrical power, people can turn to the world’s whitest paint to do the same job.

Safety is a huge concern whenever I run with my earphones in. But I need music to run. Otherwise all I hear is the sound of my own breathing. So I’ve found a compromise: I run with only one earphone in. The music sounds off. It’s an imperfect solution.

An updated pair of headphones, called AfterShokz, aim to do better. AfterShokz bills itself as using bone conducting technology to conduct music from the front of the ear, delivering sound through your cheekbone and inner ear. This keeps your eardrum (鼓膜) free to hear everything else.

“Earbuds (耳塞式耳机) are typically designed to block out all sound, which is fine when you’re inside. But when you’re outside, you need all your senses. It would be like sending you out cycling with a blindfold on,” says Rod Annet, managing director of AfterShokz.

Here’s where AfterShokz comes in. The headphones hook over the back of your head with the main “bud” resting high up against your cheek. This keeps your ear free to delight in other sounds.

So do they work? In a word, yes. During a 45-minute jog, they didn’t bounce or shift. I heard far more of my environment than I normally do: a nearby bike there; a runner passing me again to my left; and so forth.

What about the downsides? If you’re a huge fan of high-quality sound, you might find the headphones a bit tinny. One friend expressed concerns about missing the ability to get lost in the music as you might be distracted by other noises, although I personally didn’t find that an issue.

Yet those are all minor details. For me, probably the biggest problem is the price. Ranging between £ 49.96 to £ 83.29, AfterShokz headphones aren’t exactly cheap.

With all that considered, would I recommend them? Yes. AfterShokz headphones are quite useful. While out jogging, they were light, painless, and easy to use. They made me feel safer.

Hybrid (混合动力) cars are cars that run on petrol and electricity. They have a small standard petrol engine and a battery electric motor to provide electric power.

There are some differences between different models of hybrid cars, but the general principle is that the car runs on petrol, and the electric motor kicks in when additional power is required, for example, when going uphill or accelerating (加速). In some hybrid cars the petrol engine turns itself off when not needed, for example when the car has stopped at lights, keeping only the electric engine running.

Conventional (传统) cars have large engines to deal with driving uphill and accelerating. Hybrid cars have much smaller petrol engines, improved by electric motors when needed, so they use less petrol. Another way that fuel consumption (消耗) is cut is by a system of “regenerative (再生的) braking”. The electric motor is used to slow down the car, rather than conventional brakes. The energy produced by slowing the car is changed into electrical power, which is automatically stored in the battery. In effect, the battery recharges when you brake. In conventional cars the energy produced when braking is wasted.

In 1928, Ferdinand Porsche built and experimental hybrid car. The first mass-produced hybrid car, the Toyota Prius, came out in Japan at the end of 1997. However, hybrid cars became available in the USA only in 1999. As they use fuel, hybrid cars are cheaper to run. There are also many voices in place to encourage people to buy them. In some countries, hybrid cars owners pay a rate of tax, and don’t need to pay on certain roads. In some cities, hybrid cars allowed to park for free.