听力原文:

Detecting explosives
爆炸物检测
The litmus test
石蕊测试
A new way to spot home-made bombs
一种检测自制炸弹的新办法
ALTHOUGH surveillance has increased around the world following March 22nd’s bombings in Brussels, it remains extremely difficult to detect explosives carried into railway stations, shopping malls and other public places. The bombs used in Belgium might well have been picked up after the check-in desks at Zaventem Airport, but the suicide-attackers probably never intended to reach the security gate. The intensive screening carried out inside airports is not practical in many other places. That could change as new techniques are developed.

重点词汇：

1 litmus 石蕊;
2 spot 看见；看出；注意到；发现
3 screening 筛查

听力原文:

The bombs in Brussels were composed of triacetone triperoxide, known as TATP. This is the same explosive used to kill 52 people in London in train and bus attacks in 2005. It is extremely unstable, but for terrorists bent on sacrificing themselves TATP has considerable appeal since it can be made from compounds found in easily obtained materials such as paint thinners and hair-bleaching agents.

重点词汇：

1 triacetone 丙硫酮;
2 triperoxide 丙酮
3 TATP 三过氧化三丙酮
4 thinner 涂料、清漆等的）稀料，稀释剂
5 hair-bleaching agents 漂白剂
6 agents （化学）剂
7 bent on 决心要做，一心想做（通常指坏事）
8 appeal 吸引力；感染力；魅力
注释：2005年7月7日早上交通尖峰时间，4名受“基地”组织指使的英国人在伦敦三辆地铁和一辆巴士上引爆自杀式炸弹，造成52名乘客遇难，700多人受伤。此次恐怖袭击被称为伦敦七七爆炸案。

听力原文:

TATP can be detected with traditional technologies, like ion mobility spectrometry. This uses a desktop machine to analyse swabs. As the process can pick up minute traces of substances associated with explosives, it is hard to prevent at least a few molecules escaping onto someone’s hands and belongings. But even in airports, not every passenger is swabbed. Some machines sample air puffed onto passengers standing in cubicles, but it is a slow process. Dogs can pick out TATP, but handlers had been reluctant to train their animals to find the explosive because even tiny amounts can detonate. Now, though, trainers can use TATP as beads encased in a polymer that prevents detonation but also releases the odour.

重点词汇：

1 ion 离子
2 spectrometry 光谱测定法，度谱术; 谱测量;
3 ion mobility spectrometry 离子迁移率光谱测定法
4 swab （医用的）拭子，药签
5 minute traces 微小的足迹， 蛛丝马迹
6 substance 物质；物品；东西
7 molecule 分子
8 puff吹；喷；吐
9 sample 抽样检验；取样；采样
10 cubicle （大房间分隔出的）小房间，隔间
11 handler 驯兽员；（尤指）驯犬员
12 detonate（使）爆炸；引爆；起爆
13 bead 珠子；小珠
14 encase 把…装箱（或围住、包起）
15 polymer polymer 聚合物；多聚体
16 odour 气味

听力原文:

Such developments help, but airport-style security would be expensive and highly disruptive if these measures were imposed at all the entry points to crowded public places. Far better would be a system that can automatically analyse air samples and raise an alarm if any dangerous compounds are detected. That idea had seemed fanciful, but Kenneth Suslick at the University of Illinois at Urbana-Champaign thinks he has found a way to do it.

重点词汇：

1 fanciful 空想的；想象的
2 Illinois 伊利诺斯州

听力原文:

Dr Suslick’s strategy is to hunt for TATP using chemical dyes which can readily bind to reactive airborne compounds, changing colour when they do so. By using differently coloured dyes that each have an affinity for molecules of a specific compound released into the air by different explosives, the system would generate a unique colour signature when a dangerous material was nearby. Dr Suslick thinks that adding sensors onto a small cartridge-type device containing an array of different dyes would improve the system further by measuring other characteristics of airborne particles, such as their acidity and molecular polarity (the way they conduct a charge). It appears to be a complex bit of kit, but Dr Suslick is quick to point out that the method is really not much different to a multidimensional form of litmus paper.

重点词汇：

1 dye 染料；染液
2 readily 快捷地；轻而易举地；便利地
3 bind （使）联合在一起，结合
4 airborne 空气传播的
5 reactive 能起化学反应的；易反应的
6 compound 化合物
7 affinity 密切的关系；类同
8 cartridge 胶片盒；暗盒；墨盒
9 array 大堆；大群；大量
10 particle颗粒；微粒
11 acidity 酸味；酸性
12 polarity 极性（两极并存的状态）
13 molecular polarity 分子极性
14 multidimensional 多面的，多维的

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