國(guó)際科技信息

美國(guó)約翰·霍普金斯兒童中心、密西西比大學(xué)醫(yī)學(xué)中心和麻省大學(xué)醫(yī)學(xué)院的研究人員3月3日在第20屆逆轉(zhuǎn)錄病毒和機(jī)會(huì)性感染大會(huì)上報(bào)告說(shuō)，他們首次實(shí)現(xiàn)了對(duì)一名感染艾滋病病毒（HIV）嬰兒的“功能性治愈”。這項(xiàng)成果將有助于為根治兒童艾滋病病毒感染鋪平道路。

“功能性治愈”艾滋病嬰兒

據(jù)物理學(xué)家組織網(wǎng)報(bào)道，這名嬰兒的母親是位艾滋病病毒感染者，在他出生30小時(shí)后，醫(yī)生便對(duì)其實(shí)施了抗逆轉(zhuǎn)錄病毒聯(lián)合治療。一系列測(cè)試表明，嬰兒血液中的病毒在逐步減少，在他出生29天之后，病毒降低到了無(wú)法檢測(cè)的水平。治療一直持續(xù)到該嬰兒18個(gè)月大時(shí)停止。10個(gè)月后，多次對(duì)其進(jìn)行標(biāo)準(zhǔn)的血液檢測(cè)，均沒(méi)有發(fā)現(xiàn)血液中存在艾滋病病毒。HIV特異性抗體這

美國(guó)首次“功能性治愈”艾滋病嬰兒

一標(biāo)準(zhǔn)的HIV感染臨床指標(biāo)的測(cè)試結(jié)果也始終為負(fù)。

研究人員說(shuō)，這名嬰兒現(xiàn)在被視為“功能性治愈”，也就是說(shuō)，無(wú)需終身用藥，其體內(nèi)的HIV感染已被完全控制，且標(biāo)準(zhǔn)的臨床測(cè)試無(wú)法檢測(cè)到血液中的HIV復(fù)制。但“功能性治愈”患者體內(nèi)仍有少量病毒，可通過(guò)超靈敏方法識(shí)別出來(lái)，而與之相對(duì)而言的“根本性治愈”，則是指患者體內(nèi)病毒已完全清除。

研究人員認(rèn)為，可能是由于及時(shí)采用了抗病毒治療，制止了病毒宿主的形成，該嬰兒才得以治愈。病毒宿主指的是一種休眠細(xì)胞，其在大多數(shù)艾滋病患者停止治療后短短數(shù)周內(nèi)會(huì)再度引發(fā)感染，極難對(duì)付。

及早治療是關(guān)鍵

目前，為防止高風(fēng)險(xiǎn)新生兒感染HIV病毒，通常會(huì)對(duì)其施以為時(shí)6周的預(yù)防性劑量的多種抗病毒藥物聯(lián)合治療；而一旦確診感染，則改用治療性劑量。但研究人員說(shuō)，此次的特殊病例可能會(huì)改變目前的做法，因?yàn)樗癸@了在極早期采用抗逆轉(zhuǎn)錄病毒療法的治療潛力。

“立即對(duì)新生兒采取抗病毒療法，防止病毒的藏身之地在第一時(shí)間形成，由此可以幫助嬰兒清除病毒，實(shí)現(xiàn)（對(duì)感染的）長(zhǎng)期控制，而無(wú)需終身接受治療。” 該報(bào)告的主要作者、約翰·霍普金斯兒童中心的病毒學(xué)家德博拉·佩爾紹德說(shuō)。

專家表示，不需要治療、具有天然抑制艾滋病病毒的能力是極為罕見(jiàn)的，只在不到0.5%的成人艾滋病毒感染者身上觀察到，他們被稱為“精英控制者”，其免疫系統(tǒng)能抑制病毒的復(fù)制，使病毒數(shù)量保持在臨床檢測(cè)不到的水平。HIV專家一直在尋求一種方法，希望將所有的艾滋病患者轉(zhuǎn)化為“精英控制者”，而這項(xiàng)最新成果有望改變局面。

“大規(guī)模地完全根除病毒是我們的長(zhǎng)期目標(biāo)，但就目前而言，這仍是遙不可及的，而對(duì)高風(fēng)險(xiǎn)新生兒實(shí)施積極、及時(shí)、準(zhǔn)確、有針對(duì)性的抗病毒療法，可能是我們實(shí)現(xiàn)功能性治愈的最佳機(jī)會(huì)?！甭槭〈髮W(xué)醫(yī)學(xué)院免疫學(xué)家凱瑟琳·盧蘇里亞加說(shuō)。

研究人員同時(shí)提醒，他們還缺乏足夠的數(shù)據(jù)，尚不能建議改變目前的做法，用治療性劑量取代預(yù)防性劑量對(duì)高風(fēng)險(xiǎn)新生兒實(shí)施治療，不過(guò)，這名“功能性治愈”嬰兒的例子為開(kāi)展原理驗(yàn)證研究提供了理論基礎(chǔ)。佩爾紹德說(shuō)：“下一步是要證實(shí)，這究竟是對(duì)極早期抗逆轉(zhuǎn)錄病毒治療的一個(gè)極不尋常的反應(yīng)，還是一種同樣可適用于其他高風(fēng)險(xiǎn)新生兒的方法?！?/p>

First 'Functional Cure' of HIV in Baby?

A baby born two-and-ahalf years ago in Mississippi with HIV is the first case of a so-called"functional cure" of the infection,researchers announced recently.

Standard tests can no longer detect any traces of the AIDS-causing virus even though the child has discontinued HIV medication.

"We believe this is the first well-documented case of a [functional] cure," said study lead author Dr. Deborah Persaud,associate professor of pediatrics in the division of infectious diseases at Johns Hopkins Children's Center in Baltimore. The finding was presented Sunday at the Conference on Retroviruses and Opportunistic Infections, in Atlanta.

The child was not part of a study but, instead, the beneficiary of an unexpected and partly unplanned sequence of events that-- once confirmed and replicated in a formal study -- might help more children who are born with HIV or who at risk of contracting HIV from their mother eradicate the virus from their body.

Normally, mothers infected with HIV take antiretroviral drugs that can almost eliminate the odds of the virus being transferred to the baby.

If a mother doesn't know her HIV status or hasn't been treated for other reasons, the baby is given"prophylactic" drugs at birth while awaiting the results of tests to determine his or her HIV status.This can take four to six weeks to complete. If the tests are positive,the baby starts HIV drug treatment.

The mother of the baby born in Mississippi didn't know she was HIV-positive until the time of delivery.

But in this case, both the initial and confirmatory tests on the baby were able to be completed within one day, allowing the baby to be started on HIV drug treatment within the first 30 hours of life.

"Most of our kids don't get picked up that early," Persaud explained.

As expected, the baby's "viral load" -- detectable levels of HIV --decreased progressively until it was no longer detectable at 29 days of age.

Theoretically, this child(doctors aren't disclosing the gender) would have taken the medications for the rest of his or her life, said the researchers,who included doctors from the University of Massachusetts Medical School and the University of Mississippi Medical Center.

Instead, the child stayed on the regimen for only 18 months before dropping out of the medical system and discontinuing the drugs.

Ten months after stopping treatment, however, the child was again seen by doctors who were surprised to find no HIV virus or HIV antibodies with standard tests.

Ultrasensitive tests did detect infinitesimal traces of viral DNA and RNA in the blood. But the virus was not replicating -- a highly unusual occurrence given that drugs were no longer being administered, the researchers said.

德國(guó)企業(yè)創(chuàng)立了有機(jī)太陽(yáng)能電池效率世界新高

有機(jī)薄膜太陽(yáng)能技術(shù)全球領(lǐng)先的德國(guó)Heliatek公司，近日公布其有機(jī)太陽(yáng)能電池效率又創(chuàng)世界新高，達(dá)到了12%，由此打破了該公司于9個(gè)月前創(chuàng)立的10.7%的記錄。新效率已得到了專業(yè)檢測(cè)機(jī)構(gòu)的認(rèn)證。

實(shí)現(xiàn)新紀(jì)錄的電池為1.1cm2標(biāo)準(zhǔn)尺寸，含有兩種享有專利的吸收材料，它們可將不同波段中的光轉(zhuǎn)換成電。

通過(guò)兩種吸收體的組合，可以借助更高的光電壓提高對(duì)光子的吸收，更好地利用能源。由于有機(jī)光伏在高溫下的獨(dú)到性能與低輻射，12%的效率可與常規(guī)晶硅模塊及薄膜光伏14～15%的電池效率相媲美。檢測(cè)結(jié)果證實(shí)，相比于傳統(tǒng)的太陽(yáng)能技術(shù)，有機(jī)光伏的效率在弱光與高溫時(shí)超越平均水平。

這項(xiàng)成果顯示出Heliatek公司的發(fā)展戰(zhàn)略，即聚焦于低聚吸收材料的真空沉積，而非印刷聚合物。

前者在過(guò)去的10年中已經(jīng)成功地用于OLED-顯示器。真空沉積可允許超薄的同質(zhì)層沉降，最薄的僅有5nm厚。利用極易把握的超薄層沉積過(guò)程，可將一定數(shù)量的層疊在一起，生產(chǎn)有極寬的光譜吸收能力的疊層電池，甚至三結(jié)太陽(yáng)能電池。

這項(xiàng)有機(jī)太陽(yáng)能效率新紀(jì)錄是Heliatek公司科研團(tuán)隊(duì)與德國(guó)德累斯頓及烏爾姆大學(xué)聯(lián)合開(kāi)發(fā)的成果，該研發(fā)計(jì)劃得到了德國(guó)聯(lián)邦教研部、歐盟、德國(guó)研究聯(lián)合會(huì)等部門(mén)與機(jī)構(gòu)的資助?；谶@個(gè)成果，Heliatek公司計(jì)劃至2015年將轉(zhuǎn)換效率提高至15%。

該公司基于小分子（低聚物）的有機(jī)太陽(yáng)能電池技術(shù)目前已處于商業(yè)生產(chǎn)轉(zhuǎn)化之中，第一條生產(chǎn)線已于2012年春落成，主要生產(chǎn)太陽(yáng)能薄膜，提供給建材、汽車等行業(yè)的合作伙伴，供他們將半成品用作產(chǎn)能組件，擴(kuò)展自身產(chǎn)品的功能。

預(yù)計(jì)集成了Heliatek公司有機(jī)太陽(yáng)能薄膜的產(chǎn)品將于2013年年底進(jìn)入市場(chǎng)。公司計(jì)劃繼續(xù)投資，建成更大規(guī)模的生產(chǎn)線，實(shí)現(xiàn)批量生產(chǎn)，以便大幅度降低生產(chǎn)成本。

Heliatek achieves 12% organic solar cell efficiency

Organic solar films developer Heliatek, Dresden, Germany,reports that it has pushed the conversion efficiency of its organic photovoltaic (OPV) cells to 12%, which the company says is equivalent to at least 15% in conventional semiconductor-based cells.

The company says this performance, which was achieved in cooperation with the University of Ulm and TU Dresden, is a “world record achievement”, as measured by the accredited testing facility SGS.

SGS also validated Heliatek’s superior low light and high temperature performances of its OPV technology compared to traditional solar technologies.

The 12.0% record is based on a standard sized cell of 1.1 cm2, which uses a combination of two patented absorber materials that convert light of different wavelengths. Using two different absorber materials creates a stronger absorption of photons and improves energetic utilization through a higher photovoltage.

Heliatek says that thanks to OPV’s unique behavior at high temperatures and low light conditions – when its performance either improves or remains stable– the 12% efficiency figure is equivalent to about 14% to 15%efficiency of traditional solar technologies such as crystalline silicon and thin film PV.

However, while those other technologies tend to significantly lose cell efficiency with rising temperatures and decreasing solar irradiation, organic cells increase their efficiency in these conditions leading to a much higher energy harvesting in real-world environments.

Boosting ef fi ciency

Thibaud Le Séguillon, CEO of Heliatek, commented, “We are planning to reach 15% efficiency by 2015 and gradually transfer our record efficiencies into Heliatek’s roll-to-roll production line. We manufacture solar films and not solar panels.

"Our customers in the building and construction material industry, in automotive and in light structures, such as shading and street furniture, are integrating these solar films as energy harvesting components to increase the functionality of their products.”

Martin Pfeiffer, co-founder and CTO of Heliatek, added:“Achieving 12% OPV efficiency is a clear validation of Heliatek’s choice not to focus on printed polymers but to go with vacuum deposited oligomers. This technology has been used successfully for OLED displays over the last decade.

"Vacuum deposition enables extremely thin yet homogeneous layers down to a thickness of 5nm.With this well-controlled, ultra-thin film process we can deposit a large number of layers on top of each other creating tandem, or even triple junction cells, to absorb a broader spectrum of light.”

Heliatek’s latest record efficiency for OPV improves on its previous record of 10.7%, set nine months previously. To achieve the latest leap in cell efficiency, Heliatek worked with a combination of its in-house R&D know-how, as well as its strong ties with the OPV specialist universities.

One of the two key absorbers was developed and synthesized by Ulm University’s Institute of Organic Chemistry & Advanced Materials, headed by Peter B?uerle, co-founder of Heliatek.The cooperation also involved Karl Leo (co-founder of Heliatek) and Moritz Riede of the Institut für Angewandte Photophysik of TU Dresden.

新算法讓監(jiān)控復(fù)雜系統(tǒng)變簡(jiǎn)單

在一個(gè)復(fù)雜系統(tǒng)中，如包含了2萬(wàn)個(gè)互相聯(lián)系的基因的人類基因組，要想一次監(jiān)控整個(gè)系統(tǒng)幾乎是不可能的。據(jù)物理學(xué)家組織網(wǎng)近日?qǐng)?bào)道，來(lái)自美國(guó)東北大學(xué)、麻省理工大學(xué)等單位的研究人員開(kāi)發(fā)出一種新算法，能識(shí)別出復(fù)雜系統(tǒng)的子單位或必要結(jié)點(diǎn)，使監(jiān)控大型復(fù)雜系統(tǒng)成為可能。相關(guān)論文發(fā)表在最近出版的美國(guó)《國(guó)家科學(xué)院學(xué)報(bào)》上。

復(fù)雜系統(tǒng)如生物基因組、生化反應(yīng)系統(tǒng)、社會(huì)網(wǎng)絡(luò)等，由許多互相關(guān)聯(lián)的子部分組成，其中任何一個(gè)部分有了變化，都會(huì)對(duì)其余部分造成影響。因此要分析監(jiān)控一個(gè)復(fù)雜系統(tǒng)是極為困難的。“復(fù)雜系統(tǒng)的本質(zhì)是連接，各組成部分之間要憑借這些連接，才能將信息分布到整個(gè)網(wǎng)絡(luò)。因此我們不必監(jiān)控每個(gè)部分，也能從整體上把握整個(gè)系統(tǒng)?！闭撐淖髡咧?、東北大學(xué)生物學(xué)院和計(jì)算機(jī)與信息科學(xué)院物理學(xué)教授艾伯特-拉斯洛·巴拉巴斯說(shuō)，他們?cè)O(shè)計(jì)的方法利用了復(fù)雜系統(tǒng)子單位間相互依賴的特性，可超越數(shù)量限制觀察系統(tǒng)的整體情況。

利用這種新算法，研究小組首次確定了用以描述系統(tǒng)動(dòng)態(tài)學(xué)的所有數(shù)學(xué)方程，比如計(jì)算在一個(gè)生化反應(yīng)系統(tǒng)中，外圍分子之間較小的反應(yīng)對(duì)整個(gè)系統(tǒng)最終結(jié)果所產(chǎn)生的影響。通過(guò)觀察每個(gè)反應(yīng)對(duì)系統(tǒng)變量所造成的影響，就能繪制出整個(gè)系統(tǒng)的曲線圖。連結(jié)點(diǎn)是構(gòu)成曲線圖的基礎(chǔ)，每個(gè)點(diǎn)對(duì)理解系統(tǒng)其他部分而言都是不可缺少的。

“令我們吃驚的是，在絕大部分例子中，必要結(jié)點(diǎn)也是充分條件。”東北大學(xué)復(fù)雜網(wǎng)絡(luò)研究中心副教授劉陽(yáng)煜（音譯）說(shuō)，只要有了這些必要結(jié)點(diǎn)，無(wú)需其他任何部分就能知道整個(gè)系統(tǒng)的全部情況。

研究人員指出，新方法將控制論、圖論和網(wǎng)絡(luò)科學(xué)結(jié)合在一起，將大型復(fù)雜系統(tǒng)簡(jiǎn)化為一套必要的“傳感結(jié)點(diǎn)”。比如生物的新陳代謝系統(tǒng)，是由上百分子和上千生化反應(yīng)組成的集合，新算法能使識(shí)別其中生物標(biāo)記的過(guò)程大大簡(jiǎn)化。生物標(biāo)記是血液中的分子，能幫醫(yī)生辨別一個(gè)人是否健康。“目前的大部分生物標(biāo)記幾乎都是隨機(jī)選擇的，只是化學(xué)家和醫(yī)生發(fā)現(xiàn)它們管用而已?！卑屠退拐f(shuō)，“而我們的方法是可觀察的，為選擇生物標(biāo)記提供了一條理性的途徑，只要我們知道所要監(jiān)控的是什么系統(tǒng)。”

Through a sensor, clearly: Complex systems made observable

A complex system can, in principle, be observable – that is,the system's complete internal state can be reconstructed from its outputs, which would ostensibly involve describing in complete quantitative detail all of its internal state variables at once. In an actual experiment, however, such measurement is typically beyond our reach, and so is limited to a smaller number of those variables.Referred to as sensors (or sensor nodes), these key variables can be used to make the complete system observable. Recently, scientists at Northeastern University and MIT devised a graphical approach that first derives the math e mat ical equa tions describing a complex system's dynamics, and then determines the key sensors for that system. Moreover, when applying their approach to biochemical reaction systems, the researchers discovered that the derived sensors were both necessary and sufficient to describe the complete system. The scientists conclude that their findings allow a systematic exploration of many diverse natural, technological and socioeconomic systems.

Dr. Yang-Yu Liu comments on the research he, Prof. Albert-László Barabási and Prof. Jean-Jacques Slotine performed, starting with the three main challenges they faced. "The primary challenge is that for many nonlinear systems,we don't know the system parameters," Liu tells Phys.org."However, conceptually it is quite straightforward to adopt a graphical approach derived from the dynamical laws that govern a system to determine the sensors that are necessary to reconstruct the full internal state of a complex system."

In fact, control theorists have been working on the concept of system digraphs some time. Liu and his associates used this approach to study the observability problem for highly nonlinear systems, which he says that to his knowledge has not been previously addressed."The surprise," Liu adds, "was that,except for some pathological cases which almost never occur in real systems, the sensors we identified are not only necessary but also sufficient: Usually, we expect that to observe the system we'd need to monitor more sensors than just the necessary nodes, since if the topology of a dynamic system's inference diagram is very complex,it's hard to have any symmetries.However, the complicated topology somehow helped us achieve system observability." An inference diagram reveals the underlying structure of information flow or casualty when the measurements are performed.

新催化劑讓氫氣的運(yùn)輸和釋放變輕松

德國(guó)羅斯托克大學(xué)化學(xué)工程師開(kāi)發(fā)出一種新催化劑，能從液體甲醇中輕松提取氫氣，讓氫氣存儲(chǔ)和運(yùn)輸變得更加容易。研究人員認(rèn)為，這種方法消除了“氫經(jīng)濟(jì)”中的最大障礙，將來(lái)有望把氫氣“裝入”甲醇通過(guò)管道、油罐車運(yùn)輸存儲(chǔ)，用時(shí)再通過(guò)化學(xué)反應(yīng)將氫氣提取出來(lái)，為邊遠(yuǎn)農(nóng)村發(fā)電或?yàn)槠嚨冉煌üぞ咛峁┤剂稀?/p>

氫氣燃燒值很高，清潔無(wú)污染，但缺點(diǎn)是無(wú)法大量收集，很難存儲(chǔ)，運(yùn)輸也不安全。如將其壓縮液化，不僅方法很復(fù)雜而且要耗費(fèi)大量能量。幾十年來(lái)，許多化學(xué)家一直在尋找吸收存儲(chǔ)氫氣的最佳方法，讓氫氣成為便捷可靠的燃料。

目前方法之一是用固體或液體材料來(lái)吸收“封存”氫氣，雖然候選材料很多，但要么“裝”得太少，要么結(jié)合得太緊，再次釋放很不容易。甲醇能把氫氣直接轉(zhuǎn)化為液體燃料，利用催化劑可把氫氣和一氧化碳結(jié)合成甲醇，同時(shí)甲醇也能吸收大量氫氣，約為本身重量的12.5%。但甲醇也存在釋放氫氣的問(wèn)題，要讓它釋放氫氣，以往的方法要把甲醇加熱到200攝氏度，并施加25到50個(gè)大氣壓。

羅斯托克大學(xué)化學(xué)工程師馬賽厄斯·貝爾和同事開(kāi)發(fā)出一種可溶解的釕基催化劑，能在65到95攝氏度和常壓下，有效地從存儲(chǔ)甲醇中釋放出氫氣。“這節(jié)約的能量是難以估計(jì)的。”貝爾說(shuō)，把甲醇變成一種切實(shí)可行的“裝氫箱”的目的基本達(dá)到，將來(lái)有望給手機(jī)、計(jì)算機(jī)、汽車燃料電池供電。

英國(guó)牛津大學(xué)化學(xué)家埃德曼·唐也一直在研究氫氣存儲(chǔ)，他將新方法稱為一個(gè)“重要發(fā)現(xiàn)”，尤其是反應(yīng)不需要高溫，和氫燃料電池運(yùn)行所產(chǎn)生的廢熱大致相同，這意味著能把甲醇—?dú)錃夥磻?yīng)和氫電電池結(jié)合起來(lái)，這是很有吸引力的。雖然還有些障礙，但這種甲醇—?dú)錃廪D(zhuǎn)化法是值得嘗試的，因?yàn)橹苯佑眉状继峁﹦?dòng)力的話，氫燃料電池的效率是一般燃料電池的兩倍。

貝爾還指出，該工藝目前還處于初期階段，實(shí)現(xiàn)商業(yè)化還要再等幾年。技術(shù)方面還存在一些障礙，尤其是針對(duì)大規(guī)模反應(yīng)。

比如用來(lái)驅(qū)動(dòng)汽車的話，要求反應(yīng)每秒產(chǎn)生24升氫氣，而實(shí)驗(yàn)室反應(yīng)每分鐘只產(chǎn)生幾毫升氫氣；催化劑也必須很穩(wěn)定，能存放數(shù)月或數(shù)年之久，目前能達(dá)到至少3周；此外，反應(yīng)中產(chǎn)生的二氧化碳也要被吸收以減少碳排放。

Liquid storage could make hydrogen a feasible fuel

A process for extracting hydrogen from a liquid fuel could remove one of the biggest hurdles to a 'hydrogen economy', its discoverers say.

They have developed a catalyst that harvests the gas from methanol, a liquid fuel that —unlike hydrogen itself — can be easily transported and stored.

Matthias Beller, a chemical engineer at the University of Rostock in Germany, and his colleagues hope that methanol might one day be sluiced through pipelines and poured into tankers,before chemical reactions convert the liquid back to hydrogen where it is needed — for example to provide power to off-grid villages,or run cars or mobile devices.

Hydrogen has a high energy density and is completely clean,burning to leave behind only water vapour as waste.

It cannot be mined in large amounts, but proponents of a hydrogen economy say that it could be produced in vast quantities from water using excess electricity from wind turbines and solar plants.

Unfortunately, because hydrogen is a gas it is difficult to store and transport safely unless compressed or liquefied, which is cumbersome and takes a lot of energy. Many chemists have spent decades studying how best to trap hydrogen for use as a fuel.

Liquid storage

Locking the gas up in the form of solid or liquid chemicals is one answer. Many materials proposed for hydrogen storage, however,either don’t trap much, or hold onto the hydrogen so tightly that it takes an unfeasible amount of energy to retrieve.

That was the problem with methanol.

It is straightforward to turn hydrogen into the liquid fuel: a well-known reaction combines hydrogen and carbon monoxide gases using commercial catalysts.Methanol also traps a lot of hydrogen (12.5% by weight).

Yet to release the gas,chemists have previously had to heat liquid methanol to 200 °C at 25–50 times atmospheric pressure.

But Beller and his colleagues report today in Nature1 that they have discovered a soluble ruthenium-based catalyst that can efficiently turn methanol into hydrogen at a mere 65–95 °C, and at ambient pressure.

"It is difficult to estimate how much energy will be saved," says Beller.

The process is still at an early stage, years away from commercialization. But he thinks that it could be enough to make methanol a viable energy carrier,potentially delivering hydrogen for fuel cells in mobile phones,computers or even cars.

Edman Tsang, a chemist at the University of Oxford, UK, who also works on storing hydrogen in liquids including methanol2,says that the work is a "major discovery". In particular, he says,the low temperature of the reaction is attractive because it is about the same temperature as the waste heat from an operating hydrogen fuel cell. That means that it may be possible to combine a methanol–hydrogen reaction with a fuel cell that guzzles up the gas to produce electricity.

Technical hurdles

There are technical hurdles to overcome, however — not least of which is scaling up the reaction.To produce enough power to run a car, for example, the reaction would have to yield some 24 litres of hydrogen a second; in the lab,Beller has demonstrated only millilitres of flow per minute.

The catalyst would also need to be stable for months or years,whereas Beller has so far shown only that it is stable for at least three weeks.

美國(guó)科學(xué)家利用轉(zhuǎn)基因工程讓植物葉子含油脂

美國(guó)密歇根州立大學(xué)研究人員26日表示，他們通過(guò)轉(zhuǎn)基因工程獲得了葉子含油脂的植物。此舉有望促進(jìn)生物燃料的生產(chǎn)以及改善動(dòng)物飼料的營(yíng)養(yǎng)。

在傳統(tǒng)的生物燃料研究中，因植物種子能自然產(chǎn)生油脂，葉和莖等組織不會(huì)存儲(chǔ)油脂，人們關(guān)注的重點(diǎn)是如何提高植物種子的油脂含量，幾乎沒(méi)有人研究利用植物葉和莖生產(chǎn)生物燃料的問(wèn)題。

在新研究中，研究人員利用藻類涉及產(chǎn)生油脂的基因使得其他植物在其葉子中存儲(chǔ)油脂或植物油。

這對(duì)多數(shù)植物而言，在自然狀況下是十分罕見(jiàn)的現(xiàn)象。

相關(guān)的研究成果刊登在新出版的《植物細(xì)胞》雜志上。

密歇根州立大學(xué)生物化學(xué)和分子生物教授克里斯多夫·本寧是研究項(xiàng)目的負(fù)責(zé)人，研究小組的成員來(lái)自密歇根州立大學(xué)和大湖生物能源研究中心。

本寧說(shuō)，不少研究人員都在試圖提高植物的能量密度，新研究成果其實(shí)是實(shí)現(xiàn)相同目標(biāo)的不同途徑。

作為被驗(yàn)證了的概念，它有望用于促進(jìn)植物內(nèi)生產(chǎn)生物燃料的油脂的產(chǎn)量，同時(shí)提高動(dòng)物飼料的營(yíng)養(yǎng)水平。

在研究過(guò)程中，本寧和同事首先選取了單細(xì)胞綠藻的5個(gè)基因，并從中找到一個(gè)在置入擬南芥植物后成功地提高其葉子組織中油脂量的基因。

隨后，他們將轉(zhuǎn)基因擬南芥喂給毛蟲(chóng)幼蟲(chóng)食用，發(fā)現(xiàn)食用轉(zhuǎn)基因擬南芥幼蟲(chóng)的體重比食用普通擬南芥幼蟲(chóng)的要大，從而確認(rèn)轉(zhuǎn)基因植物的確含有更高的營(yíng)養(yǎng)成分和更多的能量。

對(duì)于下階段的研究，本寧和同事們將努力提高那些具有經(jīng)濟(jì)價(jià)值的草和藻的油脂產(chǎn)量。本寧認(rèn)為這是值得追逐的目標(biāo)，如果從植物的葉、莖和種子中都能提取油脂，那么植物潛在的能量將翻倍。

此外，本寧表示，藻類能夠在貧瘠的農(nóng)地上生長(zhǎng)，在糧食與燃油爭(zhēng)奪土地的辯論中，會(huì)成為重要的變數(shù)。如果藻類能夠通過(guò)基因工程不斷地生產(chǎn)豐富的油脂，那么它們將替代傳統(tǒng)的農(nóng)業(yè)作物。

大湖生物燃料研究中心主任、密歇根州立大學(xué)生物化學(xué)和分子生物杰出教授肯尼斯

克艾格斯特認(rèn)為，該研究成果代表著產(chǎn)油植物轉(zhuǎn)基因工程的重要進(jìn)展，將幫助人們?cè)谔岣邆鹘y(tǒng)和非傳統(tǒng)作物產(chǎn)量、質(zhì)量和利潤(rùn)的開(kāi)發(fā)方面撰寫(xiě)新篇章。

Fat Worms Play Role in Algal Biofuels

Fat worms confirm are playing a role in improved biofuel and animal feed production.

Researchers from Michigan State University (MSU) have successfully engineered a plant with oily leaves, a feat that could improve biofuel production.

The research was led by Christoph Benning, MSU professor of biochemistry and molecular biology along with a team from the Great Lakes Bioenergy Research Center.

The results of the study were published in the journal, The Plant Cell, and show that researchers could us an algae gene involved in oil production to engineer a plant that stores lipids or vegetable oil in it leaves. This is uncommon for most plants.

To date, little research has been done to examine the oil production of leaves and stems because in nature, most plants don’t store lipids in these tissues.

“Many researchers are trying to enhance plants’ energy density, and this is another way of approaching it,” Benning said. “It’s a proof-of-concept that could be used to boost plants’ oil production for biofuel use as well as improve the nutrition levels of animal feed.”

Benning and his colleagues began by identifying five genes from one-celled green algae.

From the five, they identified one that, when inserted into Arabidopsis thaliana, successfully boosted oil levels in the plant’s leaf tissue.

Next, to confirm that the improved plants were more nutritious and contained more energy, the research team fed them to caterpillar larvae, who gained more weight than worms that ate regular leaves.

The research team is now focusing on the enhancing oil production in grasses and algae that have economic value.

Benning says the benefits of the research make it worth pursuing.

“If oil can be extracted from leaves, stems and seeds, the potential energy capacity of plants may double,” he said. “Further,if algae can be engineered to continuously produce high levels of oil, rather than only when they are under stress, they can become a viable alternative to traditional agricultural crops.”

Moreover, algae can be grown on poor agricultural land – a big plus in the food vs. fuel debate,he added.

Ultimately the team believes they are helping to write a new chapter in the development and production of quantity, quality and profitability of traditional and nontraditional crops for use for feed and fuel.

納米粒子遞送藥物技術(shù)有新進(jìn)展

人體免疫系統(tǒng)能識(shí)別并摧毀外來(lái)物。除了細(xì)菌、病毒，遞送藥物的納米粒子、植入的起搏器和人工關(guān)節(jié)等也是外來(lái)物，同樣會(huì)引發(fā)免疫反應(yīng)，導(dǎo)致藥物失效、排斥或發(fā)炎。據(jù)物理學(xué)家組織網(wǎng)2月21日?qǐng)?bào)道，美國(guó)賓夕法尼亞大學(xué)科學(xué)家開(kāi)發(fā)出一種新方法，給這些治療設(shè)備貼上蛋白質(zhì)“通行證”，讓它們能順利通過(guò)人體的防御系統(tǒng)。相關(guān)論文發(fā)表在最近的《科學(xué)》雜志上。

“身體對(duì)入侵的外來(lái)物會(huì)一視同仁地加以排斥。”論文第一作者、賓夕法尼亞大學(xué)分子與細(xì)胞生物物理學(xué)實(shí)驗(yàn)室研究生派爾·羅德里格斯說(shuō)，這是由身體天然免疫系統(tǒng)所引發(fā)的。這一過(guò)程涉及多種細(xì)胞，如巨噬細(xì)胞能發(fā)現(xiàn)、吞掉并破壞入侵者；血清蛋白會(huì)黏在目標(biāo)物上，引起巨噬細(xì)胞注意，一旦巨噬細(xì)胞確定黏住的是外來(lái)物就會(huì)吞掉它，或發(fā)信號(hào)召集其他巨噬細(xì)胞一起來(lái)包圍它。為避免納米粒子引發(fā)天然免疫反應(yīng)，早期的辦法是給它們涂一層高分子的“刷子外衣”，這些“刷子”從納米粒子中伸出來(lái)，阻止各種血清蛋白黏在它表面。但這只能暫緩一時(shí)而不能最終解決問(wèn)題。賓夕法尼亞大學(xué)工程與應(yīng)用科學(xué)學(xué)院化學(xué)與生物分子工程教授丹尼斯 迪斯科和研究小組另辟蹊徑：讓巨噬細(xì)胞相信納米粒子是“自己人”而放過(guò)它們。

早在2008年，迪斯科小組發(fā)現(xiàn)人體細(xì)胞膜上有一種叫做CD47的蛋白，它能與巨噬細(xì)胞受體SIRPa結(jié)合。就像巡警檢查人們的通行證，CD47蛋白會(huì)告訴巨噬細(xì)胞是“自己人，別吃我”。隨后有其他研究人員破解了CD47和SIRPa的連接結(jié)構(gòu)。

利用這些信息，迪斯科小組繪制出了執(zhí)行類似CD47蛋白功能所需的最小氨基酸序列，并將這種“小肽”折疊起來(lái)作為固體“通行證”。他們用化學(xué)方法合成了這種小肽，將其黏附在抗癌藥物遞送粒子上，然后注射到小鼠體內(nèi)檢驗(yàn)其功效。這些小鼠經(jīng)過(guò)基因改造，其巨噬細(xì)胞具有和人類相同的SIRPa受體。

研究人員給小鼠注射了兩種納米粒子：一種攜帶小肽通行證，另一種沒(méi)有，然后檢測(cè)小鼠免疫系統(tǒng)要多久能識(shí)別出來(lái)?！拔覀兠?0分鐘抽一次血，檢測(cè)兩種納米粒子各剩下多少。”羅德里格斯說(shuō)，“最初注射兩種粒子的比例是1∶1，20分鐘到30分鐘后，有小肽的粒子數(shù)是沒(méi)有小肽的4倍?！薄斑@證明小肽確實(shí)抑制了巨噬細(xì)胞的反應(yīng)。我們引起它們之間的互動(dòng)，然后又克服了它?！钡纤箍普f(shuō)。對(duì)治療用的納米粒子而言，它們只需活到發(fā)現(xiàn)目標(biāo)，不必?zé)o限期地留在體內(nèi)，即使多出半小時(shí)時(shí)間已能帶來(lái)很大利益；而對(duì)起搏器之類的長(zhǎng)久植入體內(nèi)的設(shè)備來(lái)說(shuō)，則需要另外的表面蛋白結(jié)合物，讓它們能和免疫系統(tǒng)長(zhǎng)期和平共處。

研究人員還指出，這些小肽在進(jìn)入實(shí)際應(yīng)用前，還需進(jìn)一步研究，將其減少到只有幾個(gè)氨基酸。這一步很關(guān)鍵，通行證分子越簡(jiǎn)單，就越容易合成。如果能在一臺(tái)機(jī)器上統(tǒng)一制造，并能方便地修改以適應(yīng)多種植入物和注射劑，就能粘黏在多種藥物遞送工具上，也能黏在專門(mén)抗體上瞄準(zhǔn)癌細(xì)胞或其他疾病組織。

Protein 'passport' helps nanoparticles get past immune system

The body's immune system exists to identify and destroy foreign objects, whether they are bacteria, viruses, flecks of dirt or splinters. Unfortunately,nanoparticles designed to deliver drugs, and implanted devices like pacemakers or artificial joints, are just as foreign and subject to the same response.

Now, researchers at the University of Pennsylvania School of Engineering and Applied Science and Penn's Institute for Translational Medicine and Therapeutics have figured out a way to provide a "passport" for such therapeutic devices, enabling them to get past the body's security system.

The research was conducted by professor Dennis Discher,graduate students Pia Rodriguez,Takamasa Harada, David Christian and Richard K. Tsai and postdoctoral fellow Diego Pantano of the Molecular and Cell Biophysics Lab in Chemical and Biomolecular Engineering at Penn.

It was published in the journal Science.

"Fromyourbody's perspective," Rodriguez said, "an arrowhead a thousand years ago and a pacemaker today are treated the same—as a foreign invader.

"We'd really like things like pacemakers, sutures and drugdelivery vehicles to not cause an inflammatory response from the innate immune system."

The innate immune system attacks foreign bodies in a general way.

Unlike the learned response of the adaptive immune system,which includes the targeted antibodies that are formed after a vaccination, the innate immune system tries to destroy everything it doesn't recognize as being part of the body.

This response has many cellular components, including macrophages—literally "big eaters"—that find, engulf and destroy invaders. Proteins in blood serum work in tandem with macrophages; they adhere to objects in the blood stream and draw macrophages' attention. If the macrophage determines these proteins are stuck to a foreign invader, they will eat it or signal other macrophages to form a barrier around it.

Drug-delivery nanoparticles naturally trigger this response, so researchers' earlier attempts to circumvent it involved coating the particles with polymer "brushes."These brushes stick out from the nanoparticle and attempt to physically block various blood serum proteins from sticking to its surface.

However, these brushes only slow down the macrophagesignaling proteins, so Discher and colleagues tried a different approach: Convincing the macrophages that the nanoparticles were part of the body and shouldn't be cleared.

美國(guó)研制新型超級(jí)電池 幾秒鐘內(nèi)完成手機(jī)充電

目前，美國(guó)科學(xué)家最新研制一種超級(jí)電池，它們被稱為微型石墨烯超級(jí)電容，其充電和放電速度比普通電池快1000倍。這種超級(jí)電池是采用單原子厚度的碳層構(gòu)成，能夠很容易制造并整合成為器件，未來(lái)有望制造更小的手機(jī)。

研究小組稱，這項(xiàng)技術(shù)突破能夠在最短時(shí)間內(nèi)對(duì)手機(jī)和汽車快速充電，同時(shí)可用于制造體積較小的器件。美國(guó)加州大學(xué)洛杉磯大學(xué)材料科學(xué)和工程系教授理查德·卡恩說(shuō)：“集合電子電路的能量存儲(chǔ)單元的設(shè)計(jì)制造存在著挑戰(zhàn)，經(jīng)常局限于整體系統(tǒng)的微型化?！?/p>

為了研制這種微型超級(jí)電池，研究人員使用二維石墨烯層，在第三維立體層面其厚度僅有單個(gè)原子。同時(shí)，研究小組發(fā)現(xiàn)使用一種標(biāo)準(zhǔn)DVD燒錄技術(shù)能夠很容易制造這種新型電池。

卡恩說(shuō)：“制造微型超級(jí)電容的傳統(tǒng)方法涉及到密集型光刻技術(shù)，但被證實(shí)很難制造成本低廉的器件，因此在商業(yè)應(yīng)用領(lǐng)域受限。目前，我們基于適用于大眾的光速寫(xiě)DVD燒錄技術(shù)，可以僅用部分傳統(tǒng)裝置成本制造出石墨烯微型超級(jí)電容。使用這種技術(shù)，我們利用廉價(jià)材料僅不足30分鐘在一個(gè)光盤(pán)上制造100多個(gè)微型超級(jí)電池?！?/p>

為了使超級(jí)電池更具有效性，兩個(gè)分離電極的放置方式必須使其表面積最大化。這將使超級(jí)電池能夠存儲(chǔ)更多電能。之前的微型電池是多層石墨烯堆疊在一起作為電極，有點(diǎn)兒像三明治面包片。

在最新設(shè)計(jì)的超級(jí)電池中，研究人員使用叉合模型(類似于互相交織的手指)將電極并排放在一起。這將有助于實(shí)現(xiàn)兩個(gè)電極表面積的最大化，盡管這同時(shí)也會(huì)減少電解液中離子需要擴(kuò)散的路徑。

最終這種超級(jí)電池能夠存儲(chǔ)更多的電能，更快地完成充電。研究人員表示，人們甚至可以在家中完成這種超級(jí)電池的制造。

UCLA researchers develop new technique to scale up production of graphene micro-supercapacitors

While the demand for eversmaller electronic devices has spurred the miniaturization of a variety of technologies, one area has lagged behind in this downsizing revolution: energystorage units, such as batteries and capacitors.

Now, Richard Kaner,a member of the California NanoSystems Institute at UCLA and a professor of chemistry and biochemistry, and Maher El-Kady,a graduate student in Kaner's laboratory, may have changed the game.

The UCLA researchers have developed a groundbreaking technique that uses a DVD burner to fabricate micro-scale graphenebased supercapacitors — devices that can charge and discharge a hundred to a thousand times faster than standard batteries. These micro-supercapacitors, made from a one-atom–thick layer of graphitic carbon, can be easily manufactured and readily integrated into small devices such as next-generation pacemakers.

The new cost-effective fabrication method, described in a study published this week in the journal Nature Communications, holds promise for the mass production of these supercapacitors, which have the potential to transform electronics and other fields.

"The integration of energystorage units with electronic circuits is challenging and often limits the miniaturization of the entire system," said Kaner, who is also a professor of materials science and engineering at UCLA's Henry Samueli School of Engineering and Applied Science. "This is because the necessary energy-storage components scale down poorly in size and are not well suited to the planar geometries of most integrated fabrication processes."

"Traditional methods for the fabrication of microsupercapacitors involve laborintensive lithographic techniques that have proven difficult for building cost-effective devices,thus limiting their commercial application," El-Kady said. "Instead,we used a consumer-grade LightScribe DVD burner to produce graphene micro-supercapacitors over large areas at a fraction of the cost of traditional devices. Using this technique, we have been able to produce more than 100 microsupercapacitors on a single disc in less than 30 minutes, using inexpensive materials."

The process of miniaturization often relies on flattening technology, making devices thinner and more like a geometric plane that has only two dimensions.In developing their new microsupercapacitor, Kaner and El-Kady used a two-dimensional sheet of carbon, known as graphene, which only has the thickness of a single atom in the third dimension.

Kaner and El-Kady took advantage of a new structural design during the fabrication. For any supercapacitor to be effective,two separated electrodes have to be positioned so that the available surface area between them is maximized. This allows the supercapacitor to store a greater charge. A previous design stacked the layers of graphene serving as electrodes, like the slices of bread on a sandwich. While this design was functional, however, it was not compatible with integrated circuits.

In their new design, the researchers placed the electrodes side by side using an interdigitated pattern, akin to interwoven fingers.This helped to maximize the accessible surface area available for each of the two electrodes while also reducing the path over which ions in the electrolyte would need to diffuse. As a result, the new supercapacitors have more charge capacity and rate capability than their stacked counterparts.

Interestingly, the researchers found that by placing more electrodes per unit area, they boosted the micro-supercapacitor's ability to store even more charge.

Kaner and El-Kady were able to fabricate these intricate supercapacitors using an affordable and scalable technique that they had developed earlier. They glued a layer of plastic onto the surface of a DVD and then coated the plastic with a layer of graphite oxide.