首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Antiseptics(杀菌剂) have saved countless lives, but they are most effective when the bacteria they are attacking are individual cel
Antiseptics(杀菌剂) have saved countless lives, but they are most effective when the bacteria they are attacking are individual cel
admin
2013-06-02
38
问题
Antiseptics(杀菌剂) have saved countless lives, but they are most effective when the bacteria they are attacking are individual cells in suspension. Once bacteria have attached themselves to solid surfaces and formed films, they are far harder to eradicate with standard disinfectants. Bacterial pollution of medical devices is a particular problem, as those devices are then used on people whose immune systems may be in less than best condition. Surgical instruments may be treated with ultraviolet light, but that is not appropriate for everything. The result is that infections arising from bacteria attached to surfaces in clinics and hospitals are reckoned to cause up to 1.4m deaths per year.
In order to develop a better method of disinfection, a team led by David Whitten of the University of New Mexico and Kirk Schanze of the University of Florida set out to design the equivalent of a mousetrap for bacteria. The device they came up with is an empty capsule five microns across. It is made of alternating layers of two polymers’(聚合体) ,one of which is positively charged, and the other negatively so. These opposite charges serve to hold the capsule together.
The polymers in question also absorb light in a way that is likely to transfer the absorbed energy to nearby oxygen molecules (氧分子) to create what is known as singlet oxygen, a particularly reactive form of the element that would kill any bacteria inside the capsule.
To test this idea, the two researchers ran a series of experiments in which they exposed their newly built microcapsules to Pseudomonas aeruginosa, a fatal bacterium commonly, found in hospitals, and also to Cobetia marina, a bacterium that frequently adheres to ships and marine equipment, causing dirt. They found that in both cases the microcapsules attracted and captured bacteria that were nearby. After one hour of exposure to light, they report in a forthcoming issue of Applied Materials & Interfaces, the capsules killed more than 95% of the bacteria used in the study.
What kills the bacteria is clear: it is the singlet oxygen. What is attracting them into the microcapsules, though, is not well understood. The researchers infer that the positive electric charge may have the function of attracting bacteria, since many bacteria are negatively charged and would thus be attracted to the polymer in question. Alternatively, because both bacteria and polymers are repelled by water they may be pushed together by this joint repulsion. However it works, the result is what Dr. Whitten describes as a micro-sized Roach Motel ("Bacteria check in, but they don’t check out"). If the idea can be scaled up, it may prove a useful weapon in the fight against hospital-caused infection and marine-dirt alike.
According to the passage, the antiseptics will be less effective when ______.
选项
A、the bacteria are floating in individual cells
B、the bacteria pollute the medical devices in the hospital
C、the bacteria adhere to solid surfaces, wrapped by films
D、the disinfectants are not so standard
答案
C
解析
细节题。由定位句可知,当细菌粘附到固体表面并且形成薄膜时,一般的消毒剂便很难将其消除,即此时杀菌剂的效能降低,C符合题意。
转载请注明原文地址:https://kaotiyun.com/show/oBn7777K
0
大学英语六级
相关试题推荐
Probablyatnotimeinhislifeistheaverageindividualmorelikelytobeconcernedabouttheproblemofmoralvaluesandstan
Probablyatnotimeinhislifeistheaverageindividualmorelikelytobeconcernedabouttheproblemofmoralvaluesandstan
Probablyatnotimeinhislifeistheaverageindividualmorelikelytobeconcernedabouttheproblemofmoralvaluesandstan
Probablyatnotimeinhislifeistheaverageindividualmorelikelytobeconcernedabouttheproblemofmoralvaluesandstan
Probablyatnotimeinhislifeistheaverageindividualmorelikelytobeconcernedabouttheproblemofmoralvaluesandstan
Probablyatnotimeinhislifeistheaverageindividualmorelikelytobeconcernedabouttheproblemofmoralvaluesandstan
Probablyatnotimeinhislifeistheaverageindividualmorelikelytobeconcernedabouttheproblemofmoralvaluesandstan
Probablyatnotimeinhislifeistheaverageindividualmorelikelytobeconcernedabouttheproblemofmoralvaluesandstan
随机试题
SavingMoneyWhereyousaveyourmoneyoftendependsonwhatyouaresavingfor.Ifyouaresavingtobuyadictionaryorto
下列有关类脂中错误的叙述是
氯原酸具有如下哪些性质()
房地产经纪合同是双务合同,双方当事人存在着()关系。
根据《税收征收管理法》,我国现行的税率中()适用于从量计征。
贷款期限的审查要点有()。
习近平2016年4月在安徽调研时指出,在当前经济下行压力加大、社会问题矛盾增多的情况下,尤其要履行好()的兜底责任。
有人认为,公民在行使自己的权利时,只要动机是好的,其他并不重要。这一观点忽视了我们在行使权利时:
怎样理解“学生的发展”?
已知,则秩r(AB+2A)=______。
最新回复
(
0
)