Disposing(处理) of waste has been a problem since humans started producing it. As more and more people choose to live close together in cities, the waste-disposal problem becomes increasingly difficult.

    During the eighteenth century, it was usual for several neighboring towns to get together to select a faraway spot as a dumpsite. Residents or trash haulers(垃圾托运者) would transport household rubbish, rotted wood, and old possessions to the site. Periodically(定期的) some of the trash was burned and the rest was buried. The unpleasant sights and smells caused no problem because nobody lived close by.

    Factories, mills, and other industrial sites also had waste to be disposed of. Those located on rivers often just dumped the unwanted remains into the water. Others built huge burners with chimneys to deal with the problem.

    Several facts make these choices unacceptable to modern society. The first problem is space. Dumps, which are now called landfills, are most needed in heavily populated areas. Such areas rarely have empty land suitable for this purpose. Property is either too expensive or too close to residential(住宅区的)neighborhoods. Long-distance trash hauling has been a common practice, but once farm areas are refusing to accept rubbish from elsewhere, cheap land within trucking distance of major city areas is almost nonexistent.

    Awareness of pollution dangers has resulted in more strict rules of waste disposal. Pollution of rivers, ground water, land and air is a price people can no longer pay to get rid of waste. The amount of waste, however, continues to grow.

    Recycling efforts have become commonplace, and many towns require their people to take part. Even the most efficient recycling programs, however, can hope to deal with only about 50 percent of a city's reusable waste.

    Japanese researchers say they have developed a new type of glass that can heal itself from cracks and breaks. Glass made from a low weight polymer (聚合物) called “polyether-thioureas” can heal breaks when pressed together by hand without the need for high heat to melt the material.

    The research, published in Science, by researchers led by Professor Takuzo Aida from the University of Tokyo, promises healable glass that could potentially be used in phone screens and other fragile (易碎的) devices, which they say are an important challenge for sustainable (可持续的) societies.

    While self-healing rubber and plastics have already been developed, the researchers said that the new material was the first hard substance of its kind that can be healed at room temperature. The new polymer glass is “highly robust mechanically yet can readily be repaired by compression (压紧) at broken surfaces”.

The characteristics of the polyether-thioureas glass were discovered by accident by a graduate school student named Yu Yanagisawa, who was preparing the material as a glue. Yanagisawa found that when the surface of the polymer was cut, the edges would adhere to each other, healing to form a strong sheet after being manually compressed for 30 seconds at 21℃. Further experiments found that the healed material regained its original strength after a couple of hours.

    Yanagisawa told NHK that he didn't believe the results at first and repeated his experiments several times to confirm the finding. He said, “I hope the repairable glass becomes a new environment-friendly material that avoids the need to be thrown away if broken.”

    This is not the first time a polymer has been suggested as a healable screen for devices such as smartphones. Researchers at the University of California suggested the use of polymer that could stretch to 50 times its original size and heal breaks within 24 hours.

    Smartphone manufacturers have already used self-healing materials in devices. LG's G Flex 2 shipped in 2016 with a coating on its back was capable of healing minor scratches over time, although failed to completely repair heavier damage.

    According to the research conducted by repair firm iMend, over 21% of UK smartphone users were living with a broken screen, with smashed displays being one of the biggest issues alongside poor battery life.

    With more and more people swimming at beaches every year, the problem of sharks (鲨鱼) takes on new importance. There are people who still insist that sharks never attack human beings unless they are bleeding or wounded, but this belief has not been clearly proved. In the past few years, on both the Atlantic and Pacific coasts, there have been cases of shark attacks which resulted in death. And just how many of the swimmers who have disappeared were victims of shark attacks will never be known. Clearly, these violent fish can be dangerous. Several species are known to attack human beings, and it is believed by some experts that certain sharks, once having tasted human blood, develop a taste for it.

    The chances that one will come across a shark are small, but certain precautions should be taken by everyone. (A precaution is something you do in order to prevent something dangerous or unpleasant from happening.) Putting hands or legs over the side of a boat in warm waters is to be avoided. Swimming far out from beaches is inviting trouble. No swimmer should go great distances from shore alone, or go into the water when nobody else is about. Skin divers, particularly those who go deep down in the water or among rocks and ledges (暗礁) that serve as hiding places for sharks, are taking unnecessary risks.

    If one is in a boat that is rubbed against by a shark, he should remember the creature is not trying to upset his boat; it is probably trying to rub off sea lice (海虱). A blow, especially on the nose, will drive it off. If a swimmer comes across a shark, he should swim away as quietly as possible, trying to avoid making it angry. He should also head for shore (岸) as quickly as possible.

    We talk a lot in the U.S. about success. Success is the dream and the end point. And not by coincidence the idea that hard work leads to personal success is as American as apple pie.

    But the reality is that sometimes we fail. And sometimes things, through no fault of our own, don't go our way. We're faced with a life-changing diagnosis (诊断), the passing of a loved one or job loss. We don't, as a society, have as much to say here.

    I think uncertainty does us all harm. We'd feel better equipped to deal with uncertainty if we talked about it more. I had so fully bought into the belief that with enough effort, I could control what happened in my life. I actually caught myself thinking I could "work my way out" of my cancer. As it turns out, cancer doesn't really care about one's work.

    We might also make wiser decisions — this isn't just a feel-good exercise. For example, technology and medicine have progressed to the point that many patients are living longer than they would have even a decade ago. These are achievements worth celebrating. And yet I wonder if the focus on success is sometimes misguided here as well. If it is one reason why we tend to pursue expensive end-of-life treatments, they often accomplish little other than to make a patient's final days painful and frightening. The fact is that, when asked, many patients would rather focus on living meaningfully in their final days.

    My hope here is to make a case for thinking about meaning, in the same way we think about pursuing success. In that spirit, I've asked several people, each of whom has met misfortune, how they find meaning in their lives. The diversity in their responses reflects the fact that there are no right or wrong answers here. We each can find meaning in different things.

    "What kind of rubbish are you?" This question might normally cause anger, but in Shanghai it has aroused complaints over the past week. On July 1st the city introduced strict rubbish-sorting regulations as a model for the country. Residents must divide their waste into four separate categories and throw it into specific public bins. They must do so at scheduled times, when monitors are present to ask the nature of one's rubbish, otherwise, they will face fines or worse.

    Shanghai authorities are responding to an obvious environmental problem. It generates 9 million tonnes of garbage a year, more than London's annual output and rises quickly. But like other cities in China, it lacks a recycling system. Individuals who fail to recycle could be fined up to 200 yuan (＄29). For repeat, the city can add black marks to their credit records, making it harder for them to obtain bank loans or even buy train tickets.

    Some object to this. Peng Feng of the Shanghai Academy of Social Sciences warns that the use of the credit system is overkill, raising a risk that officials will abuse their power. But others say a tough campaign is necessary. "Slowly people will get used to it," says Li Changjun of Fudan University.

    Many residents support recycling but are frustrated by the details. Rubbish must be divided according to whether it is food, recyclable, dry or harmful, the distinctions among which can be confusing, though there are apps to help work it out. Some have complained about the rules surrounding food waste. They must put it straight in the requisite public bin, forcing them to tear open plastic bags and toss (撕开) it by hand. Most upsetting are the short windows for throwing rubbish, typically a couple of hours, morning and evening. Along with the monitors at the bins, this means that people go at around the same time and can keep an eye on what is being thrown out; no one wants to look bad.

Few people enjoyed getting shots at the doctor's office. But many of these shots are important vaccines (疫苗) that help prevent us from getting certain diseases or types of infection.

Vaccines got their start in Europe in the 1720s, when a British woman named Lady Mary Wortley Montagu was visiting Turkey. She saw Turkish doctors purposefully inoculating (接种) people with small amounts of smallpox. Smallpox is a painful, deadly disease that had no cure at the time. But Lady Montagu was amazed that the patients not only recovered, but then proved to be immune (免疫的) to the disease!

Lady Montagu quickly returned to England, excited to share this new procedure. But inoculation took many years to catch on. One problem was that no one had a correct way of inoculating people safely. Occasionally, patients would become fully infected and then begin spreading the disease. However, inoculation eventually saved enough people for it to become the common practice for preventing smallpox.

Some years later, a scientist named Edward Jenner discovered that people who had been infected with a disease called cowpox became resistant to smallpox. Cowpox was less much harmful than smallpox. Jenner convinced doctors to inoculate people with cowpox, which led to a very safe vaccine and far fewer outbreaks of smallpox. Finally, a French scientist named Louis Pasteur realized that Jenner's idea could be used to treat other diseases. Since then, vaccines have been made for many other diseases, such as polio, tetanus, and rabies.

Today, scientists and doctors continue to create new vaccines that could potentially save millions of lives worldwide.