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PM2.5是指大气中直径不大于2.5微米的颗粒物,也称为可吸入肺颗粒物.由于它能通过肺泡直接进入循环系统,对人体危害极大.为了探究空气中PM2.5的浓度与车流量是否相关,北京市某中学的同学在城市广场周边对空气进行采样,采样时段与统计结果如图:

组别

PM2.5(微克/立方米)

清晨

上班时段

中午

下班时段

(车流量最少)

(车流量大)

(车流量小)

(车流量最大)

第1组

19

89

43

97

第2组

22

83

38

98

第3组

20

86

41

99

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    Phone Soap: Charge and Clean Your Phone

    You may charge your phone every day, but do you clean your phone as much? Whatever your hands touch, your phones touch. It has been discovered that some phones have 18 times more bacteria and viruses than any surface in a public restroom. So it probably won't surprise you that a 2011 University of London study found that one in six of our phones have bacteria and viruses on them—specifically, the bacteria called E. coli.

    The research on bacteria and viruses led to the invention of Phone Soap. It is not actually liquid like dishwasher soap. It is a phone charger that uses the electromagnetic radiation (辐射) used in hospitals to kill 99.9 percent of bacteria and viruses, cleaning your phone while it charges.

    “There are really certain types of bacteria and viruses that we should not be in touch with, and they are really on our phones,” says Wes Barnes, the Phone Soap co-founder. It all started while his cousin and co-founder, Dan LaPorte, was in his cancer research lab at college. “He realized he got the idea of getting rid of bacteria and viruses on the phones,” said Barnes. “In the lab they used UV-C light for destroying them. He realized this would be the fastest, most powerful way to kill any bacteria and viruses living on electronic machines.”

    Phone Soap looks like a little metal suitcase. Your phone rests in to charge and get cleaned at the same time. Instead of plugging your phone into the wall, you'd plug it into the Phone Soap charger box. The process only takes a few minutes but, Barnes says, “The idea is that you can leave it in there overnight if you want to keep charging. Reflective paint keeps the light completely around the phone so it cleans the phone fully.”

    The co-founders spent 2013 finding the right companies and they started shipping the product in late November. By last week's International Consumer Electronics Show in Las Vegas, Phone Soap was all grown-up. Both co-founders have left their previous jobs and are selling Phone Soap nonstop. “We're shipping almost more than we can handle each day,” Barnes says. “It's been a great adventure.”