國(guó)際科技信息

The blackest substance on Earth: Nasa creates material that absorbs almost all light

Scientists already planning range of space applications, from light suppression to heat and weight reduction

Nasa engineers have come up with a material that absorbs more than 99 per cent of all light that strikes it.

Absorbent material usually pulls in ultraviolet and visible light - but this new material also captures infrared and far infrared light.

The development has even taken fellow Nasa scientists by surprise, and it promises to open new frontiers in space technology.

The team of engineers at Nasa's Goddard Space Flight Center in Greenbelt, Maryland, reported the findings recently at the SPIE Optics and Photonics conference.

John Hagopian, leading the team, said reflectance tests were extremely positive, showing that the material has 50 times more absorbtion qualities than its rivals.

He said: 'Though other researchers are reporting nearperfect absorption levels, mainly in the ultraviolet and visible, our material is darn near perfect across multiple wavelength bands - from the ultraviolet to the far infrared.

'No one else has achieved this milestone yet.'

The material is a thin coating of carbon nanotubes - hollow and multi-walled tubes about 10,000 times thinner than a strand of human hair.

They stand at 90 degrees from the surface they coat, which Nasa scientists have referred to as looking like shag-pile carpet.

It can be applied to a variety of surfaces, including silicon, silicon nitride, titanium, and stainless steel -the materials most commonly used in space science instruments.

Nasa is already thinking about practical applications for the material - the most obvious being as light-suppression on sensitive equipment.

The tiny gaps between the tubes collect and trap background light to prevent it from refl ecting off surfaces and interfering with the light that scientists actually want to measure.

Because only a small fraction of light refl ects off the coating, the human eye and sensitive detectors see the material as black.

The material could dramatically slash light refl ected off deep space equipment that is already straining to detect the faintest and farthest light sources.

Less obvious, however, is the fact that the material could also be used as a coolant.

The blacker the material, the more heat it radiates away, so the coating could be used on devices that remove heat from instruments and radiate it away to deep space.

Finally, it is a lot lighter than other materials that off less absorbtion - and weight is a critical factor in any payload being sent into space.

Goddard engineer Manuel Quijada, who co-authored the SPIE paper and carried out the refl ectance tests, said: 'We are a litile surprised by the results'.

He added: 'We knew it was absorbent. We just didn't think it would be this absorbent from the ultraviolet to the far infrared.'

Goddard scientist Ed Wollack summed it up by saying: 'This is a very promising material. It's robust, lightweight, and extremely black. It is betier than black paint by a long shot.'

美科學(xué)家研制出一種新超黑材料

美國(guó)科學(xué)家研制出一種新的超黑材料，能吸收幾乎所有照射在其上的光，吸收率超過(guò)99%，在從紫外線到遠(yuǎn)紅外線多個(gè)波段都獲得了幾近完美的吸光效果?？茖W(xué)家們表示，這種材料可廣泛應(yīng)用于從光抑制到為太空設(shè)備降溫和“瘦身”等領(lǐng)域，有望開啟太空技術(shù)研究的新時(shí)代。

新材料是由中空且多壁的碳納米管組成的一層纖薄涂層，納米管之間細(xì)小的孔隙能收集和捕獲背景光以防止其從表面反射出去對(duì)要測(cè)量的光造成干擾，由于只有很少一部分光反射離開，人眼和靈敏的探測(cè)器看到該材料為黑色。該材料可用在太空科學(xué)儀器中主要使用的硅、氮化硅、鈦、不銹鋼等不同表面上。

科學(xué)家們表示，這種材料能顯著減少用于探測(cè)宇宙中最微弱和最遙遠(yuǎn)的光的深空設(shè)備的發(fā)射光數(shù)量，因此，其最有可能用做太空傳感裝置的光抑制劑。另外，因?yàn)椴牧显胶冢漭椛涞臒崃烤驮蕉?，所以，這種涂層也可作為冷卻劑，用在一些為太空裝置移除熱量并將熱量輻射回深空的設(shè)備中。在宇宙探索中，這些太空裝置必須在超冷環(huán)境下工作，以收集宇宙深處物體發(fā)出的非常微弱的遠(yuǎn)紅外信號(hào)。如果這些裝置的冷度不夠，其產(chǎn)生的熱會(huì)淹沒微弱信號(hào)。而且，這種涂層比其他吸光材料更輕，而對(duì)任何發(fā)往太空的裝置來(lái)說(shuō)，重量都是一個(gè)非常關(guān)鍵的因素。

領(lǐng)導(dǎo)該研究的美國(guó)航空航天局（NASA）戈達(dá)德太空飛行中心的科學(xué)家約翰·哈格比安表示：“反射測(cè)試的結(jié)果表明，該材料的吸收能力是目前吸收能力最強(qiáng)材料的50多倍，其在從紫外線到遠(yuǎn)紅外線多個(gè)波段都獲得了幾近完美的吸收效果，這是前所未有的創(chuàng)新?！?/p>

該研究論文的合作者、戈達(dá)德研究中心的工程師曼紐爾·基哈達(dá)表示：“我們都對(duì)實(shí)驗(yàn)結(jié)果感到震驚，我們知道其吸光能力很強(qiáng)，但并沒有想到其能將從紫外線到遠(yuǎn)紅外線的光線一網(wǎng)打盡?！?/p>

戈達(dá)德的科學(xué)家愛德·沃萊克補(bǔ)充道：“這是一種非常有潛力的材料。它柔韌、輕便且非常黑，它比現(xiàn)在廣泛使用的吸光材料黑漆不止好一點(diǎn)?！?/p>

Malaria Vaccine Candidate RTS,S Reduces the Risk of Malaria by Half in African Children, Study Finds

First results from a large-scale Phase III trial of RTS,S, published online in the New England Journal of Medicine (NEJM), show the malaria vaccine candidate to provide young African children with significant protection against clinical and severe malaria with an acceptable safety and tolerability profile. The results were announced at the Malaria Forum hosted by the Bill & Melinda Gates Foundation in Seattle, Washington.

Half the world's population is at risk of malaria. The disease is responsible for close to 800,000 deaths each year, most of whom are children under five in sub-Saharan Africa.

5 to 17 month-old children

The trial, conducted at 11 trial sites in seven countries across sub-Saharan Africa, including a UNC-led site in Lilongwe, Malawi, showed that three doses of RTS,S reduced the risk of children experiencing clinical malaria and severe malaria by 56 percent and 47 percent, respectively. This analysis was performed on data from the first 6,000 children aged 5 to 17 months, over a 12-month period following vaccination. Clinical malaria results in high fevers and chills. It can rapidly develop into severe malaria, typified by serious effects on the blood, brain, or kidneys that can prove fatal. These first Phase III results are in line with those from previous Phase II studies.

The widespread coverage of insecticidetreated bed nets (75 percent) in this study indicated that RTS,S can provide protection in addition to that already offered by existing malaria control interventions.

6 to 12 week-old infants

The trial is ongoing and efficacy and safety results in 6 to 12 week-old infants are expected by the end of 2012. These data will provide an understanding of the efficacy profile of the RTS,S malaria vaccine candidate in this age group, for both clinical and severe malaria.

Combined data in 6 to 12 week-old infants and 5 to 17 month-old children

An analysis of severe malaria episodes so far reported in all 15,460 infants and children enrolled in the trial at 6 weeks to 17 months of age has been performed. This analysis showed 35 percent efficacy over a follow-up period ranging between 0 and 22 months (average 11.5 months).

"The publication of the first results in children aged 5 to 17 months marks an important milestone in the development of RTS,S," said Irving Hoffman, PA, MPH, co-principal investigator at the Lilongwe site. "These results confirm findings from previous Phase II studies and support ongoing efforts to advance the development of this malaria vaccine candidate," said Hoffman, who is also associate professor of medicine in the UNC School of Medicine.

Long-term efficacy

The RTS,S malaria vaccine candidate is still under development. Further information about the longer-term protective effects of the vaccine, 30 months after the third dose, should be available by the end of 2014. This will provide evidence for national public health and regulatory authorities, as well as international public health organizations, to evaluate the benefits and risks of RTS,S.

Safety

The overall incidence of serious adverse events (SAEs) in this trial was comparable between the RTS,S candidate vaccine (18 percent) recipients and those receiving a control vaccine (22 percent)

Differences in rates of SAEs were observed between the vaccines groups for specific events, such as seizures and meningitis, and were higher in the malaria vaccine group. Seizures were considered to be related to fever and meningitis was considered unlikely to be vaccine-related. These events will continue to be monitored and additional information about the safety profile of the RTS,S malaria vaccine candidate will become available over the next three years.

"Making progress against this disease has been extremely difficult, and sadly, many have resigned themselves to malaria being a fact of life in Africa. This need not be the case," said Francis Martinson, MPH, PhD, co-principal investigator in Lilongwe and country director of UNC Project-Malawi. "Renewed interest in malaria by the international community, and scientific evidence such as that we are reporting today, should bring new hope that malaria can be controlled."

The vaccine is being developed in partnership by GSK and the PATH Malaria Vaccine Initiative (MVI), together with prominent African research centers. The partners are all represented on the Clinical Trials Partnership Committee, which is responsible for the conduct of the trial. Major funding for clinical development comes from a grant by the Bill & Melinda Gates Foundation to MVI.

瘧疾疫苗研究現(xiàn)突破

英國(guó)制藥企業(yè)葛蘭素史克公司一款瘧疾疫苗的臨床測(cè)試結(jié)果顯示，它可使非洲5個(gè)月至17個(gè)月年齡段嬰兒患瘧疾的風(fēng)險(xiǎn)降低大約一半。

顯效果

這款疫苗名為“RTS，S”或Mosquirix，由葛蘭素史克公司和非營(yíng)利機(jī)構(gòu)“瘧疾疫苗倡議”合作研發(fā)。

這款疫苗1987年在葛蘭素史克公司位于比利時(shí)的生物學(xué)實(shí)驗(yàn)室首度“現(xiàn)身”，1992年起以歐洲和美國(guó)健康成年人為對(duì)象展開測(cè)試，1998年起以贊比亞為起點(diǎn)，開始在非洲測(cè)試。

“RTS，S”疫苗現(xiàn)已進(jìn)入最后一個(gè)臨床試驗(yàn)階段，以非洲布基納法索、加蓬、加納、肯尼亞、馬拉維、莫桑比克和坦桑尼亞的15460名嬰幼兒為對(duì)象，測(cè)定這一疫苗對(duì)這一瘧疾易感染群體的效用。

與6000名5個(gè)月至17個(gè)月幼兒相關(guān)的測(cè)試結(jié)果已經(jīng)得出，刊登于最新一期《新英格蘭醫(yī)學(xué)雜志》周刊，由比爾和梅琳達(dá)·蓋茨基金會(huì)主持的“瘧疾論壇”同步公開。

法新社18日援引測(cè)試結(jié)果報(bào)道，5個(gè)月至17個(gè)月幼兒注射3劑“RTS，S”疫苗后，患臨床診斷性瘧疾的風(fēng)險(xiǎn)降低56%。在瘧疾的這一發(fā)病階段，患者一般會(huì)出現(xiàn)高燒、發(fā)冷等癥狀。

另外，“RTS，S”可使這一年齡段幼兒患惡性瘧疾的風(fēng)險(xiǎn)降低47%。惡性瘧疾有可能導(dǎo)致血液、腦部和腎臟并發(fā)癥，有致命威脅。

針對(duì)6周至12周嬰兒的測(cè)試結(jié)果定于明年發(fā)布。

是突破

瘧疾由瘧原蟲引發(fā)，經(jīng)由瘧蚊傳播，嬰幼兒是易感染群體。依據(jù)世界衛(wèi)生組織公布的數(shù)據(jù)，全球78.1萬(wàn)人在2009年因瘧疾失去生命，其中90%身處非洲，92%為5歲以下兒童。

一般而言，人體遭受瘧蚊叮咬后，瘧原蟲進(jìn)入人體血液，借助血液循環(huán)到達(dá)肝臟后發(fā)育成熟、繁殖，隨后返回血液循環(huán)，影響血紅細(xì)胞，引起發(fā)燒、身體疼痛甚至一些惡性并發(fā)癥并導(dǎo)致死亡。

“RTS，S”的特別之處在于，它以寄生蟲而非病毒、細(xì)菌為打擊目標(biāo)，免疫機(jī)理是在瘧原蟲進(jìn)入人體血液后觸發(fā)人體免疫應(yīng)答，阻止這些寄生蟲進(jìn)入肝臟發(fā)育、繁殖。這款疫苗的副作用包括發(fā)燒和接種點(diǎn)紅腫，屬于兒童疫苗的常見反應(yīng)。

葛蘭素史克公司首席執(zhí)行官安德魯·威蒂說(shuō)，這款疫苗取得前所未有的突破，但只能控制瘧疾，難言根除。

比爾和梅琳達(dá)·蓋茨基金會(huì)聯(lián)合主席、美國(guó)微軟公司創(chuàng)始人比爾·蓋茨說(shuō)，這款疫苗具“里程碑”意義，根除瘧疾不再是不切實(shí)際的幻想。

存疑問(wèn)

對(duì)抗瘧疾的曙光顯現(xiàn)，但疑問(wèn)尚存。全球疫苗和免疫聯(lián)盟首席執(zhí)行官塞思·伯克利告訴法新社記者，若要把“RTS，S”推向市場(chǎng)，有效期和價(jià)格是需要解決的主要難題。

他說(shuō)，瘧疾“是最窮苦民眾面臨的巨大難題，疫苗研究耗時(shí)長(zhǎng)久，因此，成功至關(guān)重要，即便是不完美的成功”。

英國(guó)國(guó)際開發(fā)大臣安德魯·米切爾說(shuō)：“有效、長(zhǎng)效和劃算的疫苗將對(duì)控制瘧疾作出巨大貢獻(xiàn)。”

葛蘭素史克公司首席執(zhí)行官威蒂說(shuō)，這家企業(yè)已投入3億美元研發(fā)“RTS，S”疫苗，力求低價(jià)生產(chǎn)，不求利潤(rùn)，當(dāng)前尚難以確定價(jià)格。

“我們希望，可以在2015年前給非洲兒童送去這款疫苗，”威蒂說(shuō)。

Germany: A fi rst as hydrogen-hybrid power station commissioned

Described as “a world premiere”, the Prime Minister of the State of Brandenburg, Matihias Platzeck, put into operation a hydrogen-hybrid power station in Prenzlau located north of Berlin (Germany) at the end of October.

Enertrag AG, Total Deutschland GmbH, Vattenfall and Deutsche Bahn have all been involved in this groundbreaking project, which aims to demonstrate the feasibility of a safe and sustainable supply and storage of energy by using a mix of purely renewable energy sources in practical testing. This technology is also important for the energy sector, because it enables the storage of wind energy and the smooth feed-in of power from wind farms into the grid.

As shown in the diagram, the hydrogen-hybrid power station unites for the first time wind, hydrogen and biogas to one compound. The electricity generated by three wind turbines is proportionately used to manufacture carbon dioxide-free hydrogen. This green hydrogen is stored and used to produce electricity and heat by means of a combined hydrogen-biogas power plant at times of high demand and simultaneously low supply of wind energy. Moreover, this hydrogen is also used in the pumps at Total hydrogen filling stations in Berlin and Hamburg. In this way, green hydrogen from the district where the plant is located guarantees carbon dioxide-free mobility in Berlin.

The total sum of investments for this hybrid power station adds up to €21 million. This pioneering project is being sponsored by the State of Brandenburg and the Federal Ministry of Transport.

At the event held to celebrate the offi cial opening, Prime Minister Matthias Platzeck said: “The hydrogen-hybrid power station is providing a real boost! This project is an innovative, practicable and efficient contribution to be more climate-friendly. This plant, unique in the world, makes it possible to transform the fluctuating wind energy into a reliable factor that can then be deployed in the long-term as a predictable source of energy for electricity, heat and mobility. We are assisting a quantum leap in modern storage technology today."

Werner Diwald, executive board member of Enertrag also said: “The goal of providing sufficient energy to cover all our electricity, heating and mobility needs solely from renewable sources is a central facet of the energy revolution and of a sustainable, economically viable and secure energy supply. The storage of renewable energy will play a significant role here. Hydrogen is unanimously considered to represent the primary medium for this job, as it is easily able to transport and store energy in large quantities at the required speed. For this reason, ENERTRAG has chosen to focus on hydrogen and, together with industrial partners, is developing solutions that will enable the supply of energy generated using domestic resources in Germany in accordance with society’s political goals.”

世界上第一座風(fēng)力-氫混合發(fā)電站在德國(guó)投入運(yùn)營(yíng)

在德國(guó)勃蘭登堡州的普倫茨勞，世界上第一座風(fēng)力-氫氣混合發(fā)電站投入運(yùn)營(yíng)。混合發(fā)電站可以把太陽(yáng)能、風(fēng)能等可再生能源和氫氣、生物沼氣、地?zé)崮艿饶茉葱问浇Y(jié)合起來(lái)，用來(lái)解決可再生能源并網(wǎng)電量不穩(wěn)定的問(wèn)題。德國(guó)的這座電站可把風(fēng)力發(fā)電產(chǎn)生的多余電量用來(lái)電解制取氫氣，氫氣可以直接用于電動(dòng)汽車的氫燃料電池或者在用電高峰期和天然氣混合用來(lái)重新發(fā)電?，F(xiàn)階段該電站的規(guī)模還比較小，由三臺(tái)兩兆瓦的風(fēng)力發(fā)電機(jī)組成。下一階段將會(huì)繼續(xù)建設(shè)三座電站，建設(shè)更大的示范設(shè)備并將制備的氫氣并網(wǎng)到天然氣輸送管道中去。

德國(guó)的能源企業(yè)Vattenfall、德意志鐵路和石油企業(yè)Total都參與了該項(xiàng)目。目前可再生能源發(fā)電的大容量存儲(chǔ)有現(xiàn)實(shí)的需求，但是由于在制取氫氣過(guò)程中存在高達(dá)百分之六十的能量損失，該存儲(chǔ)方案的經(jīng)濟(jì)型還有待驗(yàn)證。目前對(duì)于可再生能源的大容量長(zhǎng)時(shí)間存儲(chǔ)的技術(shù)方案還很有限，無(wú)論如何，該電站的實(shí)際運(yùn)營(yíng)都被認(rèn)為是一個(gè)重要的開始。

Galaxy DNA-analysis software is now available 'in the cloud'

Galaxy -- an open-source, web-based platform for dataintensive biomedical and genetic research -- is now available as a "cloud computing" resource. A team of researchers including Anton Nekrutenko, an associate professor of biochemistry and molecular biology at Penn State University; Kateryna Makova, an associate professor of biology at Penn State; and James Taylor from Emory University, developed the new technology, which will help scientists and biomedical researchers to harness such tools as DNA-sequencing and analysis sotiware, as well as storage capacity for large quantities of scientific data. Details of the development will be published as a letier in the journal Nature Biotechnology.

Earlier papers by Nekrutenko and co-authors describing the technology and its uses are published in the journals Genome Research and Genome Biology.

Nekrutenko said that he and his team first developed the Galaxy computing system (http:// galaxyproject.org) in 2005 because "biology is in a state of shock. Biochemistry and biology labs generate mountains of data, and then scientists wonder, 'What do we do now? How do we analyze all these data?'" Galaxy, which was developed at Penn State and continues to use the University's servers for its computing power, solves many of the problems that researchers encounter by pulling together a variety of tools that allow for easy retrieval and analysis of large amounts of data, simplifying the process of genomic analysis. As described in one of the team's early papers in the journal Genome Research, Galaxy "combines the power of existing genome-annotation databases with a simple Web portal to enable users to search remote resources, combine data from independent queries, and visualize the results." Galaxy also allows other researchers to be able to review the steps that have been taken, for example, in the analysis of a string of genetic code. "Galaxy off ers scientifi c transparency -- the option of creating a public report of analyses. So, after a paper has been published, scientists in other labs can do studies in order to reproduce the results described," Nekrutenko said.

Now, Nekrutenko's team has taken Galaxy to the next level by developing an "in the cloud" option using, for example, the popular Amazon Web Services cloud. "A cloud is basically a network of powerful computers that can be accessed remotely without the need to worry about heating, cooling, and system administration. Such a system allows users, no matter where they are in the world, to shift the workload of software storage, data storage, and hardware infrastructure to this remote location of networked computers," Nekrutenko explained. "Rather than run Galaxy on one's own computer or use Penn State's servers to access Galaxy, now a researcher can harness the power of the cloud, which allows almost unlimited computing power." As a case study, the authors report on recent research published in Genome Biology in which scientists, with the help of Ian Paul, a professor of pediatrics at Penn State's Hershey Medical Center, analyzed DNA from nine individuals across three families using Galaxy Cloud. Thanks to the enormous computing power of the platiorm, the researchers were able to identify four heteroplasmic sites --variations in mitochondria, the part of the genome passed exclusively from mother to child.

"Galaxy Cloud offers many advantages other than the obvious ones, such as computing power for large amounts of data and the ability for a scientist without much computer training to use DNA-analysis tools that might not otherwise be accessible," Nekrutenko said. "For example, researchers need not invest in expensive computer infrastructure to be able to perform dataintensive, sophisticated scientific analyses."

Yet another advantage of Galaxy Cloud is its data-storage capacity. Using the Amazon Web Services cloud, researchers have the option of storing vast amounts of data in a secure location. "There are emerging technologies that will produce 100 times more data than existing 'next-generation' DNA sequencing, which already has reached the point where even more storage becomes an issue, not to mention analysis," Nekrutenko said.

新銀河系統(tǒng)利用“云”分析DNA

美國(guó)賓夕法尼亞州立大學(xué)和埃默里大學(xué)的研究人員開發(fā)的新銀河（Galaxy）系統(tǒng)，能利用“云”實(shí)現(xiàn)科學(xué)家對(duì)于與DNA（脫氧核糖核酸）測(cè)序和分析等相關(guān)軟件工具的“駕馭”，并存儲(chǔ)大量科學(xué)數(shù)據(jù)。相關(guān)研究進(jìn)展將發(fā)表在《自然·生物技術(shù)》雜志上。

生物化學(xué)和生物學(xué)實(shí)驗(yàn)經(jīng)常會(huì)產(chǎn)生如山的數(shù)據(jù)，如何分析這些數(shù)據(jù)令科學(xué)家十分頭疼。Galaxy計(jì)算系統(tǒng)是為數(shù)據(jù)密集的生物醫(yī)藥和基因研究而設(shè)的、基于網(wǎng)絡(luò)的開源平臺(tái)。其能通過(guò)聚集多個(gè)具備快速檢索功能和海量數(shù)據(jù)分析功用的工具，簡(jiǎn)化基因組分析的工程，從而解決科研人員面臨的難題。

“云”是強(qiáng)大計(jì)算機(jī)的基礎(chǔ)網(wǎng)絡(luò)，可以遠(yuǎn)程使用，無(wú)需擔(dān)心過(guò)熱、過(guò)冷和系統(tǒng)管理。這種系統(tǒng)允許用戶無(wú)論身處何方，都能轉(zhuǎn)換軟件存儲(chǔ)的工作量和硬件的基礎(chǔ)架構(gòu)，以配合遠(yuǎn)程的網(wǎng)絡(luò)計(jì)算機(jī)，同時(shí)近乎支持無(wú)限的計(jì)算能力?？蒲腥藛T無(wú)需在自己的電腦上運(yùn)行Galaxy，或者使用大學(xué)的服務(wù)器進(jìn)入Galaxy，卻仍能成為“云”的駕馭者。系統(tǒng)綜合了現(xiàn)有基因組數(shù)據(jù)庫(kù)和簡(jiǎn)易網(wǎng)絡(luò)的力量，可令用戶搜索遠(yuǎn)程的資源，整合單獨(dú)的查詢數(shù)據(jù)，并令結(jié)果可視化。同時(shí)，其他實(shí)驗(yàn)室的科研人員也可以查看Galaxy的工作進(jìn)程，例如查看對(duì)于遺傳密碼的分析，賦予科學(xué)極大的透明性。

研究小組在之前發(fā)表的論文里，描述了如何利用Galaxy云服務(wù)為9個(gè)人分析DNA?；谶@個(gè)平臺(tái)的超強(qiáng)計(jì)算能力，科研人員能夠識(shí)別出4個(gè)單細(xì)胞內(nèi)含有兩種或兩種以上的細(xì)胞質(zhì)的區(qū)域，即線粒體內(nèi)的變異，基因組的這個(gè)部分會(huì)由母親遺傳給孩子。

此外，Galaxy云服務(wù)的一大優(yōu)勢(shì)就是它的數(shù)據(jù)存儲(chǔ)和計(jì)算能力?？蒲腥藛T表示，新興技術(shù)將產(chǎn)生比現(xiàn)有的下一代DNA測(cè)序多100余倍的數(shù)據(jù)，但目前這些數(shù)據(jù)的存儲(chǔ)已經(jīng)成了問(wèn)題，更不必說(shuō)對(duì)其進(jìn)行分析。而使用網(wǎng)絡(luò)云服務(wù)，研究人員可以選擇在安全的地方存儲(chǔ)大量數(shù)據(jù)。

Galaxy的云服務(wù)還具有其他優(yōu)點(diǎn)，例如可讓對(duì)于計(jì)算機(jī)了解不多的科學(xué)家也能使用不易接觸的DNA分析工具，因此不需要在計(jì)算機(jī)的基礎(chǔ)建設(shè)方面過(guò)多投資，也能保證數(shù)據(jù)密集、復(fù)雜的科學(xué)分析得以執(zhí)行。

Zinc oxide microwires improve the performance of light-emitting diodes壓電—光電效應(yīng)可將LED效能

Researchers have used zinc oxide microwires to signifi cantly improve the efficiency at which gallium nitride light-emitting diodes (LED) convert electricity to ultraviolet light. The devices are believed to be the first LEDs whose performance has been enhanced by the creation of an electrical charge in a piezoelectric material using the piezo-phototronic eff ect.

By applying mechanical strain to the microwires, researchers at the Georgia Institute of Technology created a piezoelectric potential in the wires, and that potential was used to tune the charge transport and enhance carrier injection in the LEDs. This control of an optoelectronic device with piezoelectric potential, known as piezo-phototronics, represents another example of how materials that have both piezoelectric and semiconducting properties can be controlled mechanically.

"By utilizing this effect, we can enhance the external effi ciency of these devices by a factor of more than four times, up to eight percent," said Zhong Lin Wang, a Regents professor in the Georgia Tech School of Materials Science and Engineering. "From a practical standpoint, this new effect could have many impacts for electrooptical processes – including improvements in the energy effi ciency of lighting devices."

Details of the research were reported in the Sept. 14 issue of the journal Nano Letters. The research was sponsored by the Defense Advanced Research Projects Agency (DARPA) and the U.S. Department of Energy (DOE). In addition to Wang, the research team mainly included Qing Yang, a visiting scientist at Georgia Tech from the Department of Optical Engineering at Zhejiang University in China.

Because of the polarization of ions in the crystals of piezoelectric materials such as zinc oxide, mechanically compressing or otherwise straining structures made from the materials creates a piezoelectric potential – an electrical charge. In the gallium nitride LEDs, the researchers used the local piezoelectric potential to tune the charge transport at the p-n junction.

The effect was to increase the rate at which electrons and holes recombined to generate photons, enhancing the external efficiency of the device through improved light emission and higher injection current. "The eff ect of the piezopotential on the transport behavior of charge carriers is signifi cant due to its modifi cation of the band structure at the junction," Wang explained.

提升4倍

美國(guó)佐治亞理工學(xué)院的研究人員利用氧化鋅納米線大幅提升了氮化鎵發(fā)光二極管（LED）將電流轉(zhuǎn)化為紫外線的效能。這個(gè)裝置被認(rèn)為是首個(gè)通過(guò)壓電—光電效應(yīng)在壓電材料中產(chǎn)生電荷，從而使自身性能大幅提升的LED。相關(guān)研究報(bào)告發(fā)表在近期出版的《納米快報(bào)》雜志上。

通過(guò)在納米線上施加機(jī)械應(yīng)變，佐治亞理工學(xué)院的研究人員在其中制造了壓電電勢(shì)。該電勢(shì)被用于調(diào)整電荷的傳輸，并加強(qiáng)LED的載子注入。這種壓電電勢(shì)對(duì)于光電設(shè)備的控制被稱為壓電—光電效應(yīng)。這一效應(yīng)可增加電子和空穴重新結(jié)合以產(chǎn)生光子的速率，并通過(guò)提升發(fā)光強(qiáng)度和增加注入電流，加強(qiáng)設(shè)備的外部效能，使其提升4倍之多。

該校材料科學(xué)和工程系董事教授王中林表示，從實(shí)際情況來(lái)看，這個(gè)新效應(yīng)可對(duì)光電過(guò)程產(chǎn)生諸多影響，包括提升照明裝置的能源效率等。傳統(tǒng)的LED一般使用量子阱等結(jié)構(gòu)囚禁電子和空穴，這需要兩者長(zhǎng)時(shí)間保持足夠靠近以進(jìn)行重組。電子和空穴靠近的時(shí)間越長(zhǎng)，LED裝置的效率就越高。雖然一般LED的內(nèi)部量子效率能達(dá)到80%，但傳統(tǒng)的單p-n結(jié)點(diǎn)薄膜LED的外部效率卻只有3%。

新裝置內(nèi)的氧化鋅納米線構(gòu)成了p-n結(jié)的n，氮化鎵薄膜則可作為其中的p。自由載子將被囚禁在這個(gè)界面區(qū)域內(nèi)。壓電—光電效應(yīng)可在對(duì)設(shè)備施加0.093%壓應(yīng)力的情況下，使發(fā)光強(qiáng)度提升17倍，令結(jié)點(diǎn)電流增強(qiáng)4倍，從而使光電轉(zhuǎn)化率提高約4.25倍。而在合適外應(yīng)力的作用下，新裝置的外部效率可達(dá)到7.82%，大大超過(guò)了傳統(tǒng)LED的外量子效率。

研究小組制成的LED能發(fā)出波長(zhǎng)約為390納米的紫外線，但王中林教授認(rèn)為未來(lái)可延伸至可見光范圍，適用于各類光電設(shè)備。目前，高效的紫外線發(fā)射器在化學(xué)、生物、航空航天、軍事和醫(yī)療技術(shù)領(lǐng)域都有需要。

王中林教授還表示，此次研究開辟了利用壓電—光電效應(yīng)調(diào)整光電設(shè)備的新領(lǐng)域。大幅提升LED照明設(shè)備的效率有望帶來(lái)可觀的能源節(jié)約，這對(duì)于在綠色和可再生能源技術(shù)領(lǐng)域的應(yīng)用而言十分重要，此外，這一發(fā)現(xiàn)還能應(yīng)用于其他由電場(chǎng)控制的光學(xué)器件上。

New generation of superlattice cameras add more 'color' to night vision

Recent breakthroughs have enabled scientists from the Northwestern University's Center for Quantum Devices to build cameras that can see more than one optical waveband or "color" in the dark. The semiconducting material used in the cameras –called type-II superlatices – can be tuned to absorb a wide range of infrared wavelengths, and now, a number of distinct infrared bands at the same time

The idea of capturing light simultaneously at different wavelengths isn't new. Digital cameras in the visible spectrum are commonly equipped with detectors that sense red, green, and blue light to replicate a vast majority of colors perceived by the human eye. Multi-color detection in the infrared spectrum, however, off ers unique functionalities beyond color representation. The resonant frequencies of compounds can often be found in this spectral range, which means that chemical spectroscopy can be relayed in images real-time.

"When coupled with imageprocessing algorithms performed on multiple wavebands, the amount of information rendered in a particular scene is tremendous," said Manijeh Razeghi, Walter P. Murphy Professor in Electrical Engineering and Computer Science at the McCormick School of Engineering and director of the Center for Quantum Devices.

Razeghi's group engineered the detection energies on the cameras to be extremely narrow, close to one-tenth of an electron volt, in what is known as the longwave infrared window. Creating the cameras was diffi cult, however, because the light-absorbing layers are prone to parasitic effects. Furthermore, the detectors were designed to be stacked one on top of another, which provided spatially coincident pixel registration but added significantly to the growth and fabrication challenges. Nevertheless, a dual-band longwave infrared 320-by-256 sized type-II superlattice camera was demonstrated for the first time in the world, the results of which were published in the July 2011 issue of Optics Letiers.

Such infrared photon cameras based on another material called HgCdTe were used in disaster relief in March 2011 when a catastrophic tsunami damaged Japans' nuclear reactors. These cameras provided accurate temperature information about the reactors from unmanned aerial vehicles, providing officials the information they needed to orchestrate cooling efforts and prevent nuclear meltdown.

HgCdTe, however, is considered to be an expensive technology in the long-wave infrared due to its poor spectral uniformity and therefore yield –areas in which type-II superlatices may prove more effi cient.

"Type-II superlattices can be grown uniformly even at very long-wavelengths because its energy gap is determined by the alternating InAs and GaSb quantum well thicknesses, rather than its composition as is the case with HgCdTe," Razeghi said. The high-resolution multi-band type-II superlatice camera also off ered very impressive performances, requiring only 0.5 milliseconds to capture a frame with temperature sensitivities as good as 0.015°C. "The high-performance, multifunctionality, and low cost off ered by type-II superlatices truly make it an atiractive infrared technology," she added.

新型超晶格攝像機(jī)問(wèn)世

美國(guó)西北大學(xué)量子設(shè)備中心最近開發(fā)出一種功能強(qiáng)大的Ⅱ型超晶格攝像機(jī)，能通過(guò)調(diào)節(jié)吸收更寬波段的紅外光，讓人們能在黑夜中看到更加豐富多彩的景色。他們的研究發(fā)表在最近出版的《光學(xué)通訊》上。

可見光波段的數(shù)字?jǐn)z像機(jī)配備的探測(cè)器通常只能感測(cè)紅、綠、藍(lán)那些能被裸眼看到的顏色，而紅外波段多色彩探測(cè)提供了一種獨(dú)特的功能，不僅僅是表現(xiàn)色彩。人們?cè)谶@一光譜范圍發(fā)現(xiàn)了多種相應(yīng)頻率的化學(xué)物質(zhì)，因此能在圖像中實(shí)時(shí)表現(xiàn)化學(xué)光譜。

新一代攝像機(jī)是世界上第一個(gè)雙波段長(zhǎng)波紅外超晶格攝像機(jī)。他們?yōu)閿z像機(jī)設(shè)計(jì)的探測(cè)能量極為狹窄，接近1/10電子伏特，也就是長(zhǎng)波紅外窗口的波長(zhǎng)。探測(cè)器被設(shè)計(jì)成堆疊式，一個(gè)加在另一個(gè)上面，以使記錄的像素保持空間一致。

麥克科密工程學(xué)院電力工程于計(jì)算機(jī)科學(xué)教授、量子設(shè)備中心主管曼尼亞·雷茨表示，將該攝像機(jī)和多波段圖形處理算法結(jié)合，拍下的照片能攜帶大量信息。其高分辨率多帶寬的性能，只需0.5毫秒就能捕獲一幀清晰的畫面，且溫度敏感性達(dá)到0.015攝氏度。

這種紅外光子攝像機(jī)是在另一種紅外光探測(cè)材料碲鎘汞（HgCdTe）的基礎(chǔ)上造出來(lái)的。今年3月份，他們?cè)肏gCdTe探測(cè)攝像機(jī)拍攝日本被海嘯損壞的核反應(yīng)堆，為官方提供了精確的溫度信息，協(xié)助制定冷卻策略，預(yù)防核反應(yīng)堆的融化。

然而在長(zhǎng)紅外波領(lǐng)域，HgCdTe是一種昂貴的技術(shù)，它們的光譜狹窄單一，所以新的攝像機(jī)有更多的利益。雷茨說(shuō)：“即使在超長(zhǎng)波段，Type-Ⅱ超晶格也能被均勻地生長(zhǎng)出來(lái)，因?yàn)樗哪軒чg隙（energy gap）是由砷化銦（InAs）和銻化鎵（GaSb）交替決定，而不像HgCdTe那樣由其成分確定?！?/p>

Brain circuits connected with memory discovered

A new study published last week in Science reveals the discovery of a brain pathway that helps us link events that happen close together and play a role in memories.

The research, led by Dr. Junghyup Suh from the Massachusetts Institute of Technology found the connection between the hippocampus and the entorhinal cortex. The entorhinal cortex receives the information from areas around the brain and then passes the information to the hippocampus.

To test this pathway, the researchers used specifically bred mice. These mice had a mutant strain which allowed the cells in the entorhinal cortex to be disabled by removing doxycycline from the food the mice were fed.

When mice are presented with a sound and then within 20 seconds given a shock, they quickly learn to associate this sound with the coming shock and freeze in their tracks when the sound is heard. This experiment was conducted on the mice with the disabled entorhinal cortex and researchers discovered that the mutant mice were less likely to react to the sound.

However, when the researchers administered the shock at the same time as the sound, both mice behaved the same. This shows that there is a connection between the connection of time and the entorhinal cortex.

Another experiment used a water maze and a small platform where the mice could fi nd to stop swimming and rest. They were allowed to find the platform and then 30 seconds later placed in the water maze. The mutant mice were less likely to be able to find the platform even though they had just found it 30 seconds prior. The linking of memories to what was currently happening appeared diffi cult for these mice.

When it comes to Alzheimer’s disease, patients have difficulty with memory. In Alzheimer’s, the entorhinal cortex is one of the fi rst areas of the brain that is damaged.

科學(xué)家發(fā)現(xiàn)與記憶相連腦路線

美國(guó)麻省理工學(xué)院大腦與認(rèn)知科學(xué)院經(jīng)實(shí)驗(yàn)研究，發(fā)現(xiàn)了在記憶過(guò)程中起關(guān)鍵作用的神經(jīng)路徑，能幫人們把相繼發(fā)生的緊密事件聯(lián)系在一起。相關(guān)論文發(fā)表在上周出版的《科學(xué)》雜志上。

要想形成情景記憶和工作記憶，必須能將各種不連續(xù)的短暫因素串在一起，而這要依靠大腦中的海馬回—內(nèi)嗅皮質(zhì)網(wǎng)絡(luò)，內(nèi)嗅皮質(zhì)接收來(lái)自周邊腦區(qū)的信息，再把信息傳遞給海馬回。但是哪些神經(jīng)線路促成了這些因素互相連接還是個(gè)謎。在新研究中，麻省理工學(xué)院徐情浹（音譯）博士領(lǐng)導(dǎo)的研究小組認(rèn)為，是內(nèi)嗅皮質(zhì)到海馬回的第三層輸入端促成了這一過(guò)程的實(shí)現(xiàn)。

為了對(duì)這一路徑進(jìn)行檢測(cè)，研究小組設(shè)計(jì)了一系列實(shí)驗(yàn)。他們先給小鼠一個(gè)聲音，隨后20秒內(nèi)給它們制造一次震動(dòng)，這些小鼠很快就學(xué)會(huì)了把聲音和即將到來(lái)的震動(dòng)聯(lián)系在一起。再次聽到聲音時(shí)，它們會(huì)立即僵住，停止所有動(dòng)作。他們還專門養(yǎng)了一種特殊的轉(zhuǎn)基因鼠，這種鼠從內(nèi)嗅皮質(zhì)到海馬回的第三層輸入端被抑制，用這種轉(zhuǎn)基因鼠來(lái)實(shí)驗(yàn)時(shí)，研究人員發(fā)現(xiàn)它們對(duì)聲音的反應(yīng)更少。而在聲音和震動(dòng)同時(shí)出現(xiàn)的情況下，兩種小鼠行為相同。這表明在時(shí)間聯(lián)想記憶和內(nèi)嗅皮質(zhì)之間存在一定的聯(lián)系。

另外一項(xiàng)實(shí)驗(yàn)是利用水迷宮和一個(gè)小平臺(tái)進(jìn)行，小鼠發(fā)現(xiàn)這個(gè)平臺(tái)就可以不必游泳而上來(lái)休息，在平臺(tái)上呆30秒后它們將被放回水迷宮。而轉(zhuǎn)基因鼠找到小平臺(tái)的機(jī)會(huì)更少，即使它們30秒前剛剛在平臺(tái)上呆過(guò)。研究人員發(fā)現(xiàn)，它們很難在記憶和最近所發(fā)生事件之間建立聯(lián)系。

研究人員解釋說(shuō)，轉(zhuǎn)基因鼠在執(zhí)行空間工作記憶任務(wù)和追溯恐懼制約的編碼階段，顯出了很大缺陷。而老年癡呆癥患者在記憶方面也存在很大困難，病人的內(nèi)嗅皮質(zhì)區(qū)是最早受到傷害的腦區(qū)之一。這些結(jié)果表明，從內(nèi)嗅皮質(zhì)到海馬回之間的第三層輸入端，在短期聯(lián)想記憶中起著關(guān)鍵作用。