题目内容
Passage Three Scraps of food could soon be helping power your home, thanks to an ultra-cheap bacteria-driven battery. Its developers hope that instead of feeding the dog or making garden compost(混合肥料) ,organic household waste could top up your home’s electricity. Although such "microbial fuel cells" (MFCs)have been developed in the past, they have always proved extremely inefficient and expensive. Now Chris Melhuish and technologists at the University of the West of England(UWE)in Bristol have come up with a simplified MFC that costs as little as ￡10 to make. Right now, their fuel cell runs only on sugar cubes, since these produce almost no waste when broken down, but they aim to move on to carrot power. "It has to be able to use raw materials, rather than giving it a refined fuel," says Melhuish. Inside the Walkman-sized battery, a colony of E. coil bacteria produce enzymes that break down carbohydrates, releasing hydrogen atoms. The cell also contains chemicals that drive a series of redox, or reduction and oxidation reactions, stripping electrons from the hydrogen atoms and delivering them steadily to the fuel cell’s anode(正极). This creates a voltage that can be used to power a circuit. To prove the MFC works, the researchers are using it to power a small light-sensitive robot. And when a number of the cells are connected in series, they could power domestic appliances, running a 40-watt bulb for eight hours on about 50 grams of sugar. Earlier MFCs were inefficient because they relied on energy-hungry filters and pumps. By experimenting with different anode materials, the UWE team have figured out how to make their system work: they dump the bacteria and redox chemicals directly into the cell. In its current form, the UWE team says its organic battery can produce eight times as much power as any previous MFC. But Melhuish wants to improve this, both by scaling it up and finding a better mix of redox chemicals. According to Melhuish, his present MFC ______.
查看答案
搜索结果不匹配？点我反馈
更多问题
After a good 2003, will 2004 be betterThe past year has been a good one for Southeast Asian stocks. Markets in both Singapore and the Philippines have risen by more than 30% in dollar terms; Indonesia has surged more than 70%; and tigerish Thailand has leapt by almost 130%. Investors, needless to say, are keen to know whether lightning will strike again in the same places in 2004. There is indeed something good in store: elections.The gains of the past year are easy to explain. Indonesia, for one, has finally found its feet after years of chaos following the regional crisis in 1997. Inflation and interest rates are failing, and the economy has grown by around 4% in the past year.Thailand’s economy, meanwhile, has been doing even better. It has grown at an annual rate of 6.5% in the year as a whole. Because of low interest rates, consumers have been wildly purchasing cars and houses, helping crisis-hit companies pay off their debts and thus improving the balance sheets of Thailand’s struggling banks.Analysts tell similar tales of asset increase all around the region. Markus Rosgen, of ING, a Dutch bank, notes that Asians have been piling up deposits in their bank accounts since the crisis. With interest rates so low, he argues, they now have an incentive either to consume more or to put their savings into more lucrative investments. Either way, share prices should rise. Even now, ail Southeast Asian markets are still well below their pre-crisis highs. Moreover, points out Christopher Wood of CLSA, an investment bank, all Southeast Asian markets except Singapore serve as useful hedges against America, since they do not rise and fall with Wall Street.Unexpected events might yet upset these rosy prospects. There will be elections in the Philippines and Indonesia in 2004, and probably in Malaysia, too. Thailand goes to the polls at the beginning of 2005. Economically corrupted governments, street protests or bombing campaigns are always a possibility. But the responsible leaders seem likely to get re-elected in all four countries. Furthermore, they will spend a lot of money in the process, out of both the state budget and their own pockets, giving their economies a further boost. As a recent report by ING points out, Indonesian stocks rose in the nm-up to all of the past three elections. What has happened in Indonesia in the past year（）
Many students find the experience of attending university lectures to be a confusing and frustrating experience. The lecturer speaks for one or two hours, perhaps (61) the talk with slides, writing up important information on the blackboard, (62) reading material and giving out (63) The new student sees the other students continuously writing on notebooks and (64) what to write. Very often the student leaves the lecture (65) notes which do not catch the main points and (66) become hard even for the students to understand. Most institutions provide courses which (67) new students to develop the skills they need to be (68) listeners and note-takers. (69) these are unavailable, there are many useful study-skills guides which (70) learners to practice these skills independently. In all cases it is important to (71) the problem before actually starting your studies. It is important to (72) that most students have difficulty in acquiring the language skills (73) in college study. One way of (74) these difficulties is to attend the language and study-skills classes which most institutions provide throughout the (75) year. Another basic strategy is to find a study partner with whom it is possible to identify difficulties, exchange ideas and provide support.
设向量α=(a1，a2，…，an)T，β=(b1，b2，…，bn)T都是非零向量，且满足条件αTβ=0．记n阶矩阵A=αβT．求： (1) A2; (2) 矩阵A的特征值和特征向量．
Many students find the experience of attending university lectures to be a confusing and frustrating experience. The lecturer speaks for one or two hours, perhaps (61) the talk with slides, writing up important information on the blackboard, (62) reading material and giving out (63) The new student sees the other students continuously writing on notebooks and (64) what to write. Very often the student leaves the lecture (65) notes which do not catch the main points and (66) become hard even for the students to understand. Most institutions provide courses which (67) new students to develop the skills they need to be (68) listeners and note-takers. (69) these are unavailable, there are many useful study-skills guides which (70) learners to practice these skills independently. In all cases it is important to (71) the problem before actually starting your studies. It is important to (72) that most students have difficulty in acquiring the language skills (73) in college study. One way of (74) these difficulties is to attend the language and study-skills classes which most institutions provide throughout the (75) year. Another basic strategy is to find a study partner with whom it is possible to identify difficulties, exchange ideas and provide support.
微信支付 
支付宝支付