【推荐3】When you go running in the woods in your running tights, elastane (氨纶) is the reason why they fit you so comfortably. Elastane is an elastic material that allows the fabric to stretch and adapt to your body.

But when elastane fibres are mixed with cotton, wool, nylon or other fibres, as is the case in many clothes today, the clothes become almost impossible to recycle. It is extremely difficult to separate out the different fibres, and therefore the materials in the clothes cannot be recycled.

But this may change, says Assistant Professor Steffan Kvist Kristensen from the Interdisciplinary Nanoscience Center at Aarhus University. Together with a number of colleagues, he is behind a new technology that can separate out fibres in mixed fabrics.

“We’ve developed a method to remove elastane completely from nylon. We’re not quite there yet with cotton, because some of the cotton fibres are broken down in the process. But we believe that, with some minor adjustments, we can solve this problem,” he says.

It is not easy to separate elastane and other fibres once they have been woven(编织) together. Clothes are made by winding the main fibres, such as nylon or cotton, around the elastane fibres, which consist of long chains of molecules (分子). The fibres only break apart if we break the long chains of molecules, explains Steffan Kvist Kristensen.

By heating the clothes to 225 degrees Celsius and adding a specific alcohol, the researchers have found a method to break down the bonds in elastane chain. When this happens, the chains fall apart and the materials separate. “The whole process takes place in what is in effect a large pressure cooker that we feed the clothes into. We then add a little alcohol and a potassium hydroxide(氢氧化钾) base and heat it up. Then we let it cook for just over four hours, and when we open the lid again, the different fibres will have been separated.” says Steffan Kvist Kristensen.

So far, Steffan Kvist Kristensen and his colleagues have only experimented with two nylon stockings at a time. The technology is therefore not yet ready for application at industrial scale.

【推荐3】Tropical rainforests are disappearing at an alarming rate, and according to a new report by Rainforest Foundation Norway, humans are to blame. The world's dependence on coal, farming. soy. palm oil and mining has resulted in two-thirds of Earth's tropical rainforests being completely destroyed, and the remaining ecosystems being put closer to a tipping point.

Tropical rainforests once covered 14.5 million square kilometers of Earth's surface, but now, just one-third of that remains intact. Of the original area tropical rainforests once occupied, 34% is completely gone and 30%is suffering from degradation. All that remains is roughly 9.5 million square kilometers, and45% of that is in a degraded state, the report says.

Researchers blame human consumption for the loss. While agriculture has always been a driving factor of rainforest loss, the report said that energy consumption, international trade and the production of soy and palm oil, logging and mining have been the largest threats over the past century. A significant number of U. S. commodities rely on resources from tropical rainforests. The country heavily relies on palm oil, rubber and cocoa, all of which come from forests around the world. Oftentimes, these resources are harvested from illegally deforested lands.

Tropical rainforests are home to more than half of the Earth's biodiversity and have more carbon in living organisms than any other ecosystem. Along with supporting significant animal life, tropical rainforests are also essential to slowing down global warming. “These highly specialized ecosystems are suffering from constant abuse, through our bottomless appetite for land and resources,” said Anders Krogh, who authored the report. “We expect that upcoming UN climate and biodiversity summits provide specific targets and measures to protect intact tropical rainforests.”

The rescarchers also believe that the loss of tropical rainforests puts the whole world at risk of future pandemics. “Massive deforestation is violating nature's natural virus protection systems.” Krogh said. “The aftermath of COVID-19 should bring rainforest protection to the top of the agenda of all policy makers and world leaders concerned about preventing the outbreak of new pandemics.”

【推荐1】Andrew runs a car repair workshop in a village in London, where swallows have made their nests on the crossbeams beneath its roof. All day long, they fly in and out, bringing back insects for their hungry chicks, seemingly unconscious of the constant noise and the comings and goings of customers. However, this spring the swallows didn’t arrive back at his workshop until 10 April — the latest they have returned in nearly 40 years. Actually, the average return date has been 8 April, but this year I didn’t see one over my garden in Scottish Highlands until the 25th. Numbers are down, too. While the tide appears to have turned up from last weekend onwards, other familiar species, like house martin (毛脚燕), needle-tailed swift, etc have been very few and far between.

There are two reasons for their late arrival. Unlike many other migrating (迁徙) birds, which fatten themselves up before they depart, these species feed as they travel, replenishing (补充) lost energy by catching flying insects. For that reason, they are especially vulnerable to bad weather. And the weather in southern Europe this spring has been very unpredictable.

The second reason is that, here in Britain these years, although the weather has been mainly dry, there have been persistent easterly and northeasterly winds, which may have also slowed down the birds’ progress as they headed north.

How might this end up affecting these global travellers over the long term? Migrating birds usually live for only one or two years, so they need to get down to raising a family as soon as they return. Swallows, which usually start nesting in early April, may only be able to raise a single hatch this year, rather than two as they do in most years.

I have seen swallows all over the world and discovered just how important they are as a sign of spring: not just in Britain but all the way across the northern hemisphere. Yet I am concerned that rapid changes in the world’s climate pose a real threat to their chances of breeding successfully and their long-term future, even a week or two delays.

Fortunately, warm weather and clear skies have finally come to southern Europe, and the migration floodgates have opened. Earlier last week, down on the Somerset coast, I saw a steady passage of swallows, together with a few house martins, all heading steadily northwards. With warm sunshine and enough rain to produce quantities of insects, the swallows might be able to compensate for their lost time.

【推荐2】Dreams have fascinated people for thousands of years, yet we struggle to understand their purpose. A more recent theory suggests nighttime dreams protect visual areas of the brain from being taken over during sleep by other sensory functions, such as hearing or touch.

David Eagle-man, a neuroscience at Stanford University, has proposed the idea that dreaming is necessary to protect the visual cortex (大脑皮层)—the part of the brain responsible for processing vision. He argues that neurons (神经元) compete for survival. The brain, Eagle-man explains, distributes its resources by “implementing a do-or-die competition” for brain territory in which sensory areas “gain or lose neural territory when inputs slow, stop or shift.” Eagle-man points to people who lose sight or hearing. They show heightened sensitivity in the remaining senses because the region of the brain normally used by the lost sense is taken over by other senses.

When you sleep, you can smell, hear and feel, but visual information is absent —except during REM sleep. About 90 minutes after drifting off to sleep, you enter REM. It begins when neurons in your brain stem signal the beginning of two important tasks. Activity of these neurons, for one, paralyze major muscles, preventing the sleeper from acting out what is happening in the dream. Also, these brain cells send messages directly to the visual cortex, which starts the dreaming process. Scans of dreaming people show most of the brain activity associated with REM is within the visual cortex. Dreams are the brain’s way of fighting takeover from other senses, according to Eagle-man.

Eagle-man says that his theory can accommodate other explanations for dreams and that REM sleep may serve many purposes besides protecting the visual cortex. Think of dreaming like a computer screen saver that is set to go off every 90 minutes —except that instead of protecting against frozen images, dreams prevent the visual cortex from being occupied by other functions.

【推荐3】Characteristics of Publicity

Publicity offers several benefits. There are no costs for message time or space. An ad in prime-time television may cost $250, 000 to $5,000, 000 or more per minute, whereas a five-minute report on a network newscast would not cost anything. Publicity reaches a mass audience within a short time and new products or company policies are widely known.

Credibility about messages is high, because they are reported in independent media. A newspaper review of a movie has more believability than an ad in the same paper, because the reader associates independence with objectivity. Similarly, people are more likely to pay attention to news reports than to ads. For example, Women’s Wear Daily has both fashion reports and advertisements. Readers spend time reading the stories, but they skim through the ads. Furthermore, there may be 10 commercials during a half-hour television programme or hundreds of ads in a magazine. Feature stories are much fewer in number and stand out clearly.

Publicity also has some significant limitations. A firm has little control over messages, their timing, their placement, or their coverage by a given medium. It may issue detailed news releases and find only portions mentioned by the media, and media have the ability to be much more critical than a firm would like.

For example, in 1982, Procter Gamble faced a massive publicity problem over the meaning of its 123-year-old company logo. To fight this negative publicity, the firm had a spokesperson appear on Good Morning America to disprove the rumor. The false rumors were temporarily put to rest. However, in 1985, publicity became so troublemaking that Procter Gamble decided to remove the logo from its products.

A firm may want publicity during certain periods, such as when a new product is introduced or new store opened, but the media may not cover the introduction or opening until after the time it would aid the firm. Similarly, media determine the placement of a story; it may follow a report on crime or sports. Finally, the media decide whether to cover a story at all and the amount of coverage to be devoted to it.