VOA慢速英语2014 橡胶或很快能从杂草提炼

 

Rubber May Soon Come from Weed 橡胶或很快能从杂草提炼

People have been using products made with synthetic¹ rubber for more than a century. But high-quality tires for cars, trucks and aircraft still must contain 40 percent or more natural rubber. 

Rubber trees are not very strong. They often have problems in bad weather and suffer from disease. Naturally, then, scientists are looking for rubber substitutes.

Rubber trees grow mainly on plantations² in Southeast Asia. These trees are most productive only under the best atmospheric³ conditions. They need even amounts of rainfall and bright sunshine -- and no strong winds. Rubber trees can be infected with a plant disease. The disease has ruined many rubber plantations in South America, where the trees first grew. 

Dandelion plants are much stronger. Anyone who has dandelions on their property knows how hard it is to remove them. These flowering weeds spread easily. They grow in poor soil and do not suffer too much in a changing climate.  But qualities that make people dislike dandelions also make them a possible source of synthetic rubber. 

Scientists have known for a long time that the dandelion’s milky⁴ fluid contains latex, the main substance in raw rubber. The richest source of latex is a plant native to Kazakhstan.

Researchers from Germany are working to engineer the dandelion’s genetic⁵ material. The researchers are with the Fraunhofer Institute for Molecular⁶ Biology and Applied⁷ Ecology. Dirk Pruefer of the Institute says the goal is to produce large amounts of latex that can be used in industry.  He said one of the most difficult parts of dandelion research was to produce plants that will be economical.

“And that is why we’re working since years on the breeding program to develop new traits in the plants, stabilized⁸ traits – for example, stable rubber content.”                       

The genetically-engineered dandelion is already producing half a ton of rubber per hectare. But Dirk Pruefer says the scientists’ goal is about two times as much. They would also like to grow taller plants with upright leaves. Machine harvesting works better with such leaves.

Mr. Pruefer says a leading tire manufacturer, Continental⁹ AG, already is testing tires made with dandelion-based rubber. 

 “They made a lot of testing tissues to see the quality of the material. And what you can see is that the quality is similar to that what they have originally done with the rubber from the rubber tree.”

Researchers believe rubber-producing yellow blooms may someday cover large fields that are currently not being used because of poor soil. 

1 synthetic   

adj.合成的，人工的；综合的；n.人工制品

参考例句：

• We felt the salesman's synthetic friendliness.我们感觉到那位销售员的虚情假意。
• It's a synthetic diamond.这是人造钻石。

2 plantations   

n.种植园，大农场( plantation的名词复数 )

参考例句：

• Soon great plantations, supported by slave labor, made some families very wealthy. 不久之后出现了依靠奴隶劳动的大庄园，使一些家庭成了富豪。 来自英汉非文学 - 政府文件
• Winterborne's contract was completed, and the plantations were deserted. 维恩特波恩的合同完成后，那片林地变得荒废了。 来自辞典例句

3 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

4 milky   

adj.牛奶的，多奶的；乳白色的

参考例句：

• Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
• I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。

5 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

6 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

7 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

8 stabilized   

v.（使）稳定， （使）稳固( stabilize的过去式和过去分词 )

参考例句：

• The patient's condition stabilized. 患者的病情稳定下来。
• His blood pressure has stabilized. 他的血压已经稳定下来了。 来自《现代英汉综合大词典》

9 continental   

adj.大陆的，大陆性的，欧洲大陆的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。