洗手皂会变脏吗?
文章来源:未知 文章作者:enread 发布时间:2020-09-19 07:19 字体: [ ]  进入论坛
(单词翻译:双击或拖选)
When you see lovely little bars of lemon-thyme or lavender hand soaps on the rim1 of a sink, you know they are there to make you feel as fresh as a gardenia-scented daisy. We all know washing our hands is important, but, like washcloths and towels, can the bars of hand soap we use to clean ourselves become dirty as well?
 
Soaps are simply mixtures of sodium2 or potassium salts derived3 from fatty acids and alkali solutions during a process called saponification. Each soap molecule4 is made of a long, non-polar, hydrophobic (repelled6 by water) hydrocarbon7 chain (the "tail") capped by a polar, hydrophilic (water-soluble8) "salt" head. Because soap molecules9 have both polar and non-polar properties, they're great emulsifiers, which means they can disperse10 one liquid into another.
 
When you wash your dirty hands with soap and water, the tails of the soap molecules are repelled by water and attracted to oils, which attract dirt. The tails cluster together and form structures called micelles, trapping the dirt and oils. The micelles are negatively charged and soluble in water, so they repel5 each other and remain dispersed11 in water-and can easily be washed away.
 
So, yes, soap does indeed get dirty. That's sort of how it gets your hands clean: by latching12 onto grease, dirt and oil more strongly than your skin does. Of course, when you're using soap, you're washing all those loose, dirt-trapping, dirty soap molecules away, but a bar of soap sitting on the bathroom counter or liquid soap in a bottle can also be contaminated with microorganisms.
 
This doesn't seem to be much of a problem, though. In the few studies that have been done on the matter, test subjects were given bars of soap laden13 with E. coli and other bacteria and instructed to wash up. None of the studies found any evidence of bacteria transfer from the soap to the subjects' hands. (It should be noted14 that two of these studies were conducted by Procter & Gamble and the Dial Corp., though no contradictory15 evidence has been found.)
 
Dirty soap can't clean itself, though. A contaminated bar of soap gets cleaned via the same mechanical action that helps clean you up when you wash your hands: good ol' fashioned scrubbing. The friction16 from rubbing your hands against the soap, as well as the flushing action of running water, removes any harmful microorganisms from both your hands and the soap and sends them down the drain.


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1 rim RXSxl     
n.(圆物的)边,轮缘;边界
参考例句:
  • The water was even with the rim of the basin.盆里的水与盆边平齐了。
  • She looked at him over the rim of her glass.她的目光越过玻璃杯的边沿看着他。
2 sodium Hrpyc     
n.(化)钠
参考例句:
  • Out over the town the sodium lights were lit.在外面,全城的钠光灯都亮了。
  • Common salt is a compound of sodium and chlorine.食盐是钠和氯的复合物。
3 derived 6cddb7353e699051a384686b6b3ff1e2     
vi.起源;由来;衍生;导出v.得到( derive的过去式和过去分词 );(从…中)得到获得;源于;(从…中)提取
参考例句:
  • Many English words are derived from Latin and Greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
  • He derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》
4 molecule Y6Tzn     
n.分子,克分子
参考例句:
  • A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈?f婘??妈?成的。
  • This gives us the structural formula of the molecule.这种方式给出了分子的结构式。
5 repel 1BHzf     
v.击退,抵制,拒绝,排斥
参考例句:
  • A country must have the will to repel any invader.一个国家得有决心击退任何入侵者。
  • Particles with similar electric charges repel each other.电荷同性的分子互相排斥。
6 repelled 1f6f5c5c87abe7bd26a5c5deddd88c92     
v.击退( repel的过去式和过去分词 );使厌恶;排斥;推开
参考例句:
  • They repelled the enemy. 他们击退了敌军。 来自《简明英汉词典》
  • The minister tremulously, but decidedly, repelled the old man's arm. 而丁梅斯代尔牧师却哆里哆嗦地断然推开了那老人的胳臂。 来自英汉文学 - 红字
7 hydrocarbon tcMzs     
n.烃,碳氢化合物
参考例句:
  • During incomplete combustion some of the hydrocarbon fuel is cracked.在不完全的燃烧中,一些烃燃料裂解。
  • The hydrocarbon must be an alkene.这个碳氢化合物必定是烯烃。
8 soluble LrMya     
adj.可溶的;可以解决的
参考例句:
  • These tablets are soluble in water.这些药片可在水中溶解。
  • Camphor is soluble in alcohol.樟脑在酒精中可以溶化。
9 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
10 disperse ulxzL     
vi.使分散;使消失;vt.分散;驱散
参考例句:
  • The cattle were swinging their tails to disperse the flies.那些牛甩动着尾巴驱赶苍蝇。
  • The children disperse for the holidays.孩子们放假了。
11 dispersed b24c637ca8e58669bce3496236c839fa     
adj. 被驱散的, 被分散的, 散布的
参考例句:
  • The clouds dispersed themselves. 云散了。
  • After school the children dispersed to their homes. 放学后,孩子们四散回家了。
12 latching 2b71831177828e5f2b28e5aca264d966     
n.闭塞;闭锁;关闭;闭塞装置v.理解( latch的现在分词 );纠缠;用碰锁锁上(门等);附着(在某物上)
参考例句:
  • They have a reputation for latching onto all the latest crazes. 大家都知道他们对所有的最新时尚都有兴趣。 来自《简明英汉词典》
  • Sometimes we should tolerate people's mistakes instead of latching on to them. 有的时候我们要能够容错,不要揪着对方的失误不放。 来自互联网
13 laden P2gx5     
adj.装满了的;充满了的;负了重担的;苦恼的
参考例句:
  • He is laden with heavy responsibility.他肩负重任。
  • Dragging the fully laden boat across the sand dunes was no mean feat.将满载货物的船拖过沙丘是一件了不起的事。
14 noted 5n4zXc     
adj.著名的,知名的
参考例句:
  • The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
  • Jim is noted for arriving late for work.吉姆上班迟到出了名。
15 contradictory VpazV     
adj.反驳的,反对的,抗辩的;n.正反对,矛盾对立
参考例句:
  • The argument is internally contradictory.论据本身自相矛盾。
  • What he said was self-contradictory.他讲话前后不符。
16 friction JQMzr     
n.摩擦,摩擦力
参考例句:
  • When Joan returned to work,the friction between them increased.琼回来工作后,他们之间的摩擦加剧了。
  • Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体,并使其停止。
TAG标签: skin bacteria soaps
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