Fahad Azad, an engineer in India, invented a robot named DuctBot. The toy-car sized DuctBot measured 23 centimeters in length, 19 centimeters in width and 9 centimeters in height and weighed just two kilograms.

The robot is designed to snake through dark, narrow air conditioning ducts(管道) and clean them. A pair of LEDs fitted on the robot light up the dirty scenery, so it can be captured(抓拍) by a camera.

In order to control it more easily, Mr. Azad chooses to fix DuctBot on wheels. The robot can clean off lots of dirt, as well as dead pigeons and insects. Keeping indoor air in good quality and monitoring carbon-dioxide levels in buildings with central air conditioning is a challenge. It is important in some places where clean air can mean a difference between life and death, such as hospitals. Dirty air has a bad influence on peopled health.

EPSCO, a Dubai-based company which specializes in improving indoor air quality, read about Mr. Azad’s invention in a national newspaper after he had won an international robotics competition. EPSCO had cleaning equipment, but it needed someone to get into those ducts to do the dirty, dangerous work. Across India, for example, the task still falls to children. They are small enough to go through those ducts.

In 2005, Mr. Azad who was still at university decided to do something about it. Six years later his own company, Robosoft Systems, has Bluestar, EPSCO and the Indian Navy, some leading air condition makers, as partners.

Mr. Azad and his ten employees are currently exploring robot designs to examine oil tanks or sewage(污水) pipes. Their biggest challenge is to make the robots user-friendly enough. Mr. Azad hopes that the robot could eventually be operated not by engineers but by workers. There will be lots of difficulties they need to overcome in the future.

In 1996, someone found some very old clothes in an old mine in Nevada, USA; they included a pair of dirty old jeans. Today, those jeans are very valuable, and they are now in the Levi Strauss Archival Collection, in San Francisco. The jeans, which are over 140 years old, are the oldest pair of Levi’s 501 jeans in the world.

They are almost the same as a modern pair of 501’s; there are just some small differences in the detail For instance, today’s 501’s have two back pockets, the old pair just has one.

In 1853, a young tailor from Germany, called Levi Strauss, began working in San Francisco; Levi sold thick canvas to miners; the miners used the canvas to make tents.

One day, a miner told Levi that he could not find trousers that were strong enough for work in the gold mines. Levi decided to make some trousers out of canvas.

Very soon, he had sold all the canvas trousers he’d made! They were just what miners wanted.

However, the canvas was rather heavy and stiff Levi therefore began to look for a different textile; soon he found a heavy textile from France; it was called serge de Nimes. Americans just called this de Nimes, and this name soon got reduced to denim.

Denim was a bit lighter than canvas but it was very strong: it was ideal for miners.

However, original denim was almost white, and miners did not like the color! Their denim trousers got dirty as soon as they began working!

Levi Strauss therefore decided to use colored denim, and he chose dark blue. In 1873, he began to make denim trousers with metal rivets to make them stronger. This was a radical new idea: “Blue jeans” had arrived!

Levi’s jeans were so popular, that his company got bigger and bigger, soon, other firms were making blue jeans too. Miners liked them, but so did cowboys and other working men. Blue jeans became classic American working trousers. After the Second World War, jeans became popular all over the world. Today, blue jeans are now the international uniform worn by young people.

We are all aware of the damaging pollution that’s created by driving petrol and diesel (柴油) vehicles. Many of the world’s cities are jammed with traffic, creating poisonous gases such as nitrogen oxides. The solution for a cleaner, greener future could be electric vehicles. But how optimistic should we be?

There was much excitement last year when the UK government announced it will ban the sale of new petrol and diesel cars from 2030. But is that easier said than done?The road to global traffic being totally electric is still a long way off. Currently, battery life is an issue — a fully charged battery won’t take you as far as a full tank of petrol. Here are also limited numbers of charging points to plug an EV into.

Of course, technology is always improving. Some of the biggest tech companies, like Google and Tesla, are spending huge amounts of money developing electric cars. And most of the big car manufacturers are now making them too. Colin Herron, a consultant on low-carbon vehicle technology, told the BBC: “The big leap forward will come with solid-state batteries, which will appear first in mobile phones and laptops before they progress cars. These will charge more quickly, and give cars a a bigger range.”

Cost is another issue that may deter people switching to electric power. But some countries offer encouraging measures, such as cutting prices by reducing import taxes, and not charging for road tax and parking. Some also provide exclusive lanes for electric cars to be driven on, overtaking traditional cars which might be stuck in jams. These kinds of measures have made Norway the Country with the most electric cars per capita (人均) at more than thirty electric cars per 1,000 inhabitants.

But Colin Herron warns that “electric motoring” doesn’t mean a zero-carbon future.