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*E-Material

*Metal Alloy

*Organic & Polymer

*Composite Materials

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*Tech News & New Tech

Vol.102,2016

MCanxixun * Information

MCanxixun Information and News Service

Contents

Tech News & New Tech（技术前沿）.....................................................................3Beetle-inspired discovery could reduce frost's costly sting................................................................................3由甲壳虫启发的发现能够减少霜冻带来的高成本的结果....................................................................4

Increasing oil's performance with crumpled graphene balls..............................................................................5用褶皱的石墨烯球增加油的性能............................................................................................................6

Heavy fermions get nuclear boost on way to superconductivity........................................................................7重费密子促进原子能具有超导电性........................................................................................................9

Nanosheet growth technique could revolutionize nanomaterial production....................................................10纳米薄片生成技术会革命化纳米材料的产品......................................................................................12

Metal Alloy（金属合金）......................................................................................13Metal powders may offer alternative to fossil fuels.........................................................................................13金属粉末能够为化石燃料提供替代品..................................................................................................13

Composite Materials（复合材料）.......................................................................14Hexcel’s Carbon Fibre Composites Benefit Latest Premium Car Model.........................................................14

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MCanxixun Information and News Service

Mcanxixun * Information

赫氏公司的碳纤维复合材料有益于最新的高档车型..........................................................................14Toho Tenax Develops Energy-saving, High-productivity Carbonising Process and Surface Treatment Technologies....................................................................................................................................................15东邦特耐克斯公司研发了节能高生产力的碳化工艺和表面处理技术..............................................16

GKN Aerospace Delivers Innovative Clean Sky Wing Structure....................................................................16GKN航宇公司推出了创新型清洁天空机翼结构.................................................................................17

Building a Specialist Pilot Plant for the Production of High Value Nano-structured Powders........................17为高价值的纳米材料粉剂建造专业的试验工厂..................................................................................18

Practical Application（实际应用）.......................................................................19For this nanocatalyst reaction, one atom makes a big difference.....................................................................19由于纳米催化剂的反应，一个原子会产生重大影响..........................................................................21

Electric Eel-like Fiber Could Become New Power Source..............................................................................22电子鳗状纤维可以成为新动力能源......................................................................................................23

A nanophotonic comeback for incandescent bulbs?.........................................................................................23白炽灯泡中纳米光子的复出？..............................................................................................................25

Organic & Polymer（有机高分子材料）................................................................26Weaving a new story for COFS and MOFs......................................................................................................26为 COF和MOF编织一个新的故事......................................................................................................27

Color-changing indicators highlight microscopic damage...............................................................................29变色指示器突显微观损伤......................................................................................................................30

E-Material（电子材料）.......................................................................................31Switchable Material Could Enable New Memory Chips.................................................................................31可转换的材料可能会产生新的内存芯片..............................................................................................32

Watching electrons cool in 30 quadrillionths of a second................................................................................34在 30千万亿分之一秒的时间内看着电子冷却....................................................................................35

Electrons and liquid helium advance understanding of zero-resistance...........................................................36电子和液氮推进了对零电阻的理解......................................................................................................37

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Tech News & New Tech（技术前沿）Beetle-inspired discovery could reduce frost's costly sting

The Namib Desert Beetle lives in one of the hottest places in the world, yet it still collects airborne water. Taking a page from the beetle's playbook, Virginia Tech biomedical engineers created a way to control condensation and frost growth. Credit: Wikimedia Commons

In a discovery that may lead to ways to prevent frost on airplane parts, condenser coils, and even windshields, a team of researchers led by Virginia Tech has used chemical micropatterns to control the growth of frost caused by condensation.

Writing in Jan. 22, 2016 Scientific Reports, an online journal from the publishers of Nature, the researchers describe how they used photolithography to pattern chemical arrays that attract water over top of a surface that repels water, thereby controlling or preventing the spread of frost.

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The inspiration for the work came from an unlikely source -- the Namib Desert Beetle, which makes headlines because it lives in one of the hottest places in the world, yet it still collects airborne water.

The insect has a bumpy shell and the tips of the bumps attract moisture to form drops, but the sides are smooth and repel water, creating channels that lead directly to the beetle's mouth.

"I appreciate the irony of how an insect that lives in a hot, dry desert inspired us to make a discovery about frost," said Jonathan Boreyko, an assistant professor of Biomedical Engineering and Mechanics in the Virginia Tech College of Engineering. "The main takeaway from the Desert Beetle is we can control where dew drops grow."

Working at the Oak Ridge National Laboratory, the researchers developed their beetle-inspired, frost-controlling chemical pattern on a surface only about the size of a centimeter, but they believe the area can be scaled up to large surface areas with thirsty, hydrophilic patterns overtop of a hydrophobic, or water-repellant, surface.

"We made a single dry zone around a piece of ice," Boreyko said. "Dew drops preferentially grow on the array of hydrophilic dots. When the dots are spaced far enough apart and one of the drops freezes into ice, the ice is no longer able to spread frost to the neighboring drops because they are too far away. Instead, the drops actually evaporate completely, creating a dry zone around the ice."

Creating frost-free zones on larger surfaces could have a variety of applications - consider the water that forms and freezes on heat pump coils or the deicing with harsh chemicals that has to take place on wind turbines or airplane wings.

"Keeping things dry requires huge energy expenditures," said C. Patrick Collier, a research scientist at the Nanofabrication Research Laboratory Center for Nanophase Materials Sciences at Oak Ridge National Laboratory and a co-author of the study. "That's why we are paying more attention to ways to control water condensation and freezing. It could result in huge cost savings."

The journey of frost across a surface begins with a single, frozen dew drop, the researchers said.

"The twist is how ice bridges grow," Boreyko said. "Ice harvests water from dew drops and this causes ice bridges to propagate frost across the droplets on the surface. Only a single droplet has to freeze to get this chain reaction started."

By controlling spacing of the condensation, the researchers were able to control the speed frost grows across surfaces, or completely prevent frost.

"Fluids go from high pressure to low pressure," Boreyko said. "Ice serves as a humidity sink because the vapor pressure of ice is lower than the vapor pressure of water. The pressure difference causes ice to grow, but designed properly with this beetle-inspired pattern, this same effect creates a dry zone rather than frost."

A portion of the research was conducted at the Center for Nanophase Materials Sciences, which is a Department of Engineering Office of Science user facility. The Department of Biomedical Engineering and Mechanics at Virginia Tech provided startup support.

Source: Virginia Tech

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由甲壳虫启发的发现能够减少霜冻带来的高成本的结果

纳米布沙漠甲壳虫生活在世界上最热的地方之一，但它仍然能够收集空气中的水分。效法甲壳虫的作风，弗吉尼亚理工大学的生物医学工程师创造了一种方法来控制凝结和霜冻的增长。图片：维基共享资源

在一项可能产生防止飞机部件、冷凝器盘管、甚至是挡风玻璃结霜的方法的发现中，一组来自弗吉尼亚理工大学的研究人员已经使用化学微图案来控制综合所造成的结霜的增长。

在《自然》杂志出版商在线杂志《2016年科学报告》1月 22日的文章中，研究人员描述了他们是如何利用光刻技术来形成在排斥水的一个表面的顶部吸收水的化学陈列的图案，从而控制或预防霜冻的蔓延。

这项工作的灵感来源于一个不太可能的来源——纳米布沙漠甲虫，这令其成为头条新闻的是它生活在世界上最热的地方之一，但是它仍然能够收集空气中的水分。

该昆虫拥有一个凹凸不平的外壳，并且上凸块的前端能够吸收水分形成水珠，而两侧则比较光滑，并且排斥水分，从而形成了一条直接通往甲虫的嘴的渠道。

“我很感谢生活在火热、干燥的灌水的昆虫是如何启发我们产生一个有关于霜冻的发生的讽刺意味，”弗吉尼亚理工大学工程学院生物医学工程与力学工程系的副教授乔纳森•博列伊科表示。“沙漠甲虫的主要重点在于我们能够控制露珠产生的区域。”

橡树岭国家实验室工作的研究人员在一厘米大小的表面上开发了他们受甲虫启发的霜控制化学格局，但是他们认为，该面积能够扩展为大型表面区域，在一个疏水性或防水性的表面顶层具有干旱的亲水格局。

“我们绕着一块冰制造了一个干燥区，”博列伊科说。“露滴会优先在亲水点的陈列上形成。当点间隔足够远，并且其中一个露滴冻结成冰，那么该冰就不会再向邻近的点扩散霜冻，因为它们相距太远。相反，露滴实际上会完全蒸气，在冰的周围形成一个干燥区。”

在较大的表面上创造无霜区可能具有多种应用——考虑到在热泵线圈上形成并且结冰的水或必须在风力涡轮机或飞机机翼上进行的具有刺激性化学物质的除冰。

“让物体保持干燥需要巨大的能源支出，”橡树岭国家实验室纳米材料科学中心纳米加工研究实验室的研究科学家兼该研究的合著者 C帕特里克•科利尔。“这就是为什么我们更注重控制冰冷凝和冻结的方式。这可能会产生巨大的成本节约。”

研究人员表示，表面上结霜的旅程开始于一个单一的冰冻的露珠。“扭曲是冰桥生成的原因，”博列伊科说。“冰从露珠中获得水分，并且这会导致冰桥在表面上将霜

冻穿过液滴。只要有一个液滴开始冰结，这个连锁反应就开始了。”通过控制凝结的间距，研究人员能够在整个表面上控制霜冻的生长速度，或者完全预防霜冻。“液体从高压流向低压，”博列伊科说。“冰作为湿度水槽，因为冰的蒸气压低于水的蒸气压。压力差

会令冰增长，但是通过这种甲虫启发的陈列来进行合理地设计，同样的效果能够产生一个干燥区，而不是霜冻。”

一部分研究是在纳米加工材料科学中心进行的，该中心是科学工程办公室部门的用户设施工厂。弗吉尼亚理工大学的生物医学工程及力学部门提供了启动支持。

资料来源：弗吉尼亚理工大学

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Increasing oil's performance with crumpled graphene balls

When an automobile's engine is improperly lubricated, it can be a major hit to the pocketbook and the environment.

For the average car, 15 percent of the fuel consumption is spent overcoming friction in the engine and transmission. When friction is high, gears have to work harder to move. This means the car burns more fuel and emits more carbon dioxide into the atmosphere.

"Every year, millions of tons of fuel are wasted because of friction," said Jiaxing Huang, associate professor of materials science and engineering at Northwestern Univ.'s McCormick School of Engineering. "It's a serious problem."

While oil helps reduce this friction, people have long searched for additives that enhance oil's performance. Huang and his collaborators discovered that crumpled graphene balls are an extremely promising lubricant additive. In a series of tests, oil modified with crumpled graphene balls outperformed some commercial lubricants by 15 percent, both in terms of reducing friction and the degree of wear on steel surfaces.

Supported by the Office of Naval Research, the team's research is described in an article published online on January 25 in the Proceedings of the National Academy of Sciences. Xuan Dou, a graduate student in Huang's laboratory, is the paper's first author. Northwestern Engineering's Yip-Wah Chung, professor of materials science and engineering, and Q. Jane Wang, professor of mechanical engineering, are also authors on the paper.

About five years ago, Huang discovered crumpled graphene balls -- a novel type of ultrafine particles that resemble crumpled paper balls. The particles are made by drying tiny water droplets with graphene-based sheets inside. "Capillary force generated by the evaporation of water crumples the sheets into miniaturized paper balls," Huang said. "Just like how we crumple a piece of paper with our hands."

Shortly after making this discovery, Huang explained it to Chung during a lunch in Hong Kong by crumpling a napkin and juggling it. "When the ball landed on the table, it rolled," Chung recalled. "It reminded me of ball bearings that roll between surfaces to reduce friction."

That "a-ha!" moment led to a collaboration among the two professors and Wang, who was in the middle of editing a new Encyclopedia of Tribology with Chung.

Nanoparticles, particularly carbon nanoparticles, previously have been studied to help increase the lubrication of oil. The particles, however, do not disperse well in oil and instead tend to clump together, which makes them less effective for lubrication. The particles may jam between the gear's surfaces causing severe aggregation that increases friction and wear. To overcome this problem, past researchers have modified the particles with extra chemicals, called surfactants, to make them disperse. But this still doesn't entirely solve the problem.

"Under friction, the surfactant molecules can rub off and decompose," Chung said. "When that happens, the particles clump up again."

Because of their unique shape, crumpled graphene balls self-disperse without needing surfactants that are attracted to oil. With their pointy surfaces, they are unable to make close contact with the other graphene balls. Even when they are squeezed together, they easily separate again when disturbed.

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Huang and his team also found that performance of crumpled graphene balls is not sensitive to their concentrations in the oil. "A few are already sufficient, and if you increase the concentration by 10 times, performance is about the same," Huang said. "For all other carbon additives, such performance is very sensitive to concentration. You have to find the sweet spot."

"The problem with finding a sweet spot is that, during operation, the local concentration of particles near the surfaces under lubrication could fluctuate," Wang added. "This leads to unstable performance for most other additive particles."

Next, the team plans to explore the additional benefit of using crumpled graphene balls in oil: they can also be used as carriers. Because the ball-like particles have high surface area and open spaces, they are good carriers for materials with other functions, such as corrosion inhibition.

Source: Northwestern Univ.

用褶皱的石墨烯球增加油的性能当汽车的引擎被不适当地注入润滑油的时候，这会对你的钱包和环境产生一个重大的打击。对于普通的车来说，在克服引擎和传动装置的摩擦之后会产生 15%的耗油量。当摩擦很高的时候，齿

轮不得不更加艰难地转动。这就意味着汽车会燃耗更多的燃料，并将更多的二氧化碳排放进大气中。“每年，数以百万吨的燃料都因为摩擦被浪费掉，”西北大学麦考密工程学院的副教授 Jiaxing Huang

说。“这是个严重的问题。”虽然润滑油减少了摩擦，人们仍在长期寻找添加剂来加强润滑油的性能。Huang和他的同事发现褶皱

的石墨烯球是极好的有前途的润滑油添加剂。在一系列测试中，通过褶皱的石墨烯球改良过的润滑油胜出一些商业润滑油 15%，不仅是在降低摩擦方面，也包括钢表面的耐磨程度。

由美国海军研究办公室支持，这个团队的研究被描述在一片文章中，并在 1月 25日在线出版在美国国家科学院院刊上。Huang的实验室的研究所宣窦是这篇论文的第一作者。西北工程大学的材料科学和工程教授Yip-Wah Chung和机械工程教授Q. Jane Wang也是这篇文章的作者。

大约五年前，Huang发现了褶皱的石墨烯球是一种新型的超细粒子，有点类似压皱纸球。这种粒子是通过用内部的石墨烯薄片干燥细小水滴。“通过水分蒸发产生的毛细作用力弄皱薄片进入小型纸球中，”Huang说。“就好像我们用手弄皱了一张纸一样。”

在这个发现不久之后，在香港吃午饭期间，Huang利用褶皱一个餐巾纸并颠球对 Chung解释了它。“当球落到桌子上的时候，它滚动了，”Chung回忆。“这让我想起滚动在球面之间用来减少摩擦的球轴承

“就是这样“呵“的时刻引向了这两个教授和Wang的合作，那时Wang正在同 Chung编辑百科全书的中期阶段。

纳米粒子，尤其是碳纳米粒子，从前已经为了帮助加强油的润滑作用而被研究过。但是这种粒子在油中不仅不能很好地分散，而且相反总会凝结在一起，使得它们的润滑作用不那么有效了。这种粒子也许会堵塞在齿轮的表面造成设备系统严重增加摩擦和磨损。为了克服这个问题，过去科学家已经用另外的化学物改良过这种粒子，称之为表面活性剂，来使它们分散。但是仍不能完全解决这个问题。

“在摩擦之下，表面活性剂会被擦掉和分解，”Chung说。“当这种情况发生时，粒子又会聚集在一起。”

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由于它们独特的形状，褶皱的石墨烯球不需要吸引到油上的表面活性剂就可以自我分解。由于它们尖锐的表面，它们不能够和其它石墨烯球紧密联系。甚至当他们被挤压在一起的时候，受到干扰也会很容易就分离。

Huang和他的团队也发现褶皱的石墨烯球的性能对于它们在油中的浓度不是敏感的。“只要一点就足够了，如果你增加 10倍的浓度，性能也是一样的，”Huang说。“对其它的所有碳添加剂，这种性能对于浓度是非常敏感的。你不得不找到最有效点。”

“寻找最有效点的问题在于，在操作期间，靠近表面的粒子的局部浓度在润滑作用下会发生波动，”Wang说。“这导致了大部分其它添加剂粒子的不稳定的性能。”

接下啦，这个团队计划探索在油中使用褶皱石墨烯球的另外的益处：它们也可以被当做媒介物使用。因为这种球状粒子有着高比表面和开阔的空间，它们是带有其它功能的材料的优良载体，如腐蚀抑制。

资料来源：西北大学

Heavy fermions get nuclear boost on way to superconductivity

This microscopic closeup shows a small sample of ytterbium dirhodium disilicide, one of the most-studied "heavy fermion" composites. The scale bar in the center of the screen is one millimeter wide. Courtesy of Marc Tippmann/Technical University of Munich.

In a surprising find, physicists from the United States, Germany and China have discovered that nuclear effects help bring about superconductivity in ytterbium dirhodium disilicide (YRS), one of the most-studied materials in a class of quantum critical compounds known as “heavy fermions.”

The discovery, which is described in this week’s issue of Science, marks the first time that superconductivity has been observed in YRS, a composite material that physicists have studied for more than a decade in an effort to probe the quantum effects believed to underlie high-temperature superconductivity.

Rice University physicist and study co-author Qimiao Si said the research provides further evidence that unconventional superconductivity arises from “quantum criticality.”

“There is already compelling evidence that unconventional superconductivity is linked in both copper-based and iron-based high-temperature superconductors to quantum fluctuations that alter the magnetic order of the materials at ‘quantum critical points,’ watershed thresholds that mark the transition from one quantum phase to another,” Si said. “This work provides the first evidence that similar processes bring about superconductivity in

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the canonical heavy-fermion system YRS.”

Electrons fall within a quantum category called fermions. Heavy fermions are composite materials that contain rare earth elements. Their name stems from the fact that, at extremely low temperatures, typically less than 1 kelvin, electrons move through the material as if they were 1,000 times more massive than normal. In the latest experiments, Si said, the measured heat capacity was so large that the electrons behaved as if they were heavier still — about 1 million times heavier than normal. This occurred as the YRS was cooled to just above the point of superconductivity, around 2 millikelvins.

Si, Rice’s Harry C. and Olga K. Wiess Professor of Physics and Astronomy, also directs the Rice Center for Quantum Materials (RCQM). He said the research was conducted in collaboration with RCQM partners in Germany and China. Experiments were performed at the Walther Meissner Institute for Low Temperature Research at the Bavarian Academy of Sciences in Garching, Germany, and at the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany. Theoretical work was performed at Rice and at Renmin University of China in Beijing.

Experiments overseen by the Meissner Institute’s Erwin Schuberth and the Max Planck Institute’s Frank Steglich offered the first glimpse of YRS’ behavior at the quantum critical point. Schuberth, who has appointments at both institutes, as well as the Technical University of Munich, said what appeared to be an increase in apparent mass was actually the clue that nuclear forces were at work.

“Nothing else could have accounted for such a large change,” he said.

The bulk of experiments were performed in Garching, where Schuberth’s team used “adiabatic magnetic cooling” and other specialized techniques to make its YRS samples ultracold, about 10 times colder than those in any previous YRS experiment; this is what allowed the team to discover superconductivity.

In analyzing the evidence, Si and fellow theorist Rong Yu of Renmin University found that the arrangement of inertial spins of the ytterbium nuclei in the YRS composite helped bring about superconductivity. He said the nuclear spins became coupled at extremely low temperatures and arranged in an ordered pattern that exposed the quantum criticality of the electrons.

“In YRS, the spins of electrons are locked in a pattern that varies periodically in space and is the hallmark of an electronic order known as anti-ferromagnetism,” Si said. “An ordered arrangement of the nuclear spins acts to suppress the electronic order, and this exposes the electronic quantum criticality, which in turn drives unconventional superconductivity.”

The discovery of superconductivity in YRS followed a search lasting more than a decade. Steglich said the previous experiments demonstrate that quantum criticality in YRS brings electrons to the verge of being both localized and itinerant, a condition that was predicted by Si and collaborators in a landmark 2001 theory.

Steglich said, “In previous experiments, an external magnetic field revealed a quantum critical point with a host of truly remarkable electronic properties that had been predicted by theory. But the magnetic field also created a condition that is inhospitable to superconductivity.”

The current work succeeded in discovering superconductivity by reaching quantum criticality through the ordering of nuclear spins at ultralow temperatures, without applying an external magnetic field.

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“It is remarkable that it takes an act of nuclear spins to produce quantum criticality at zero magnetic field and realize superconductivity,” Steglich said.

Si said the new findings are important for the study of both heavy-fermion superconductivity and, more generally, the physics of quantum criticality.

“The work demonstrates that quantum criticality is a robust mechanism for bringing about unconventional superconductivity, not only in high-temperature superconductors, as had previously been shown, but also in heavy-fermion materials that are the canonical example of quantum critical behavior in every other respect,” Si said.

Study co-authors include Marc Tippmann of the Meissner Institute; Lucia Steinke of both the Meissner Institute and the Max Planck Institute for Chemical Physics of Solids; Stefan Lausberg, Alexander Steppke, Manuel Brando and Christoph Geibel, all of the Max Planck Institute for Chemical Physics of Solids; and Cornelius Krellner of both the University of Frankfurt and the Max Planck Institute for Chemical Physics of Solids.

The research was supported by the German Research Foundation, the Robert A. Welch Foundation and the National Science Foundation.

Source: Rice University

重费密子促进原子能具有超导电性

这个微观特写镜头显示了镱二聚二硅化物的小样本，它是最充分研究的“重费密子”复合材料之一。这个屏幕中心的比例尺是一毫米宽。由Marc Tippmann/慕尼黑工业大学提供，

在一项令人惊讶的发现中，来自美国、德国和中国的物理学家发现原子能的作用能帮助引发镱二聚二硅化物（YRS）的超导电性，它是量子论关键化合物的级别中最充分研究的材料，以“重费密子”著称。

这个发现被描述在这周《科学》的期刊中，标记出这是第一次在YRS中发现超导电性，这种复合材料物理学家们已经研究了超过十年了，企图探知它被认为位于高温超导电性之下的量子效应。

莱斯大学的物理学家和研究共同作者 Qimiao Si说这项研究为由“量子临界”引起的非惯例超导电性提供了更进一步的证明。

“已经有一个非常有说服力的证据证明非常规超导电性和量子涨落的铜基和铁基的高温超导电性有所链接，更改了在‘量子临界点’的地磁顺序，分水岭临界值标记了从一个量子阶段到另一个量子极端的过渡，”Si说。“这个工作为相似的过程在典型的重费密子中系统 YRS会产生超导电性提供了第一证据。”

电子属于一种被称为费密子的量子种类。重费密子是包含着稀土元素的复合材料。它们的名字是有事10


实由来的，即在极端低温情况下，一般少于 1开尔文，电子穿过材料比正常的要多出 1000倍。在最近的试验中,Si说，测量过的热容量是如此之大以至于这些电子表现得像更重了，大概比正常的要重 100万倍。这在YRS只需被冷却到大概 2毫开尔文以上的超导电性的点的时候就会发生。

Si、莱斯大学的 Harry C. 和物理与航天学教授Olga K. Wiess也指导了赖斯量子材料中心（RCQM）。他说这项研究和德国和中国的 RCQM的同伴合作进行。试验在位于德国加尔兴的巴伐利亚科学院沃尔特迈斯纳低温研究机构进行，以及在德国德累斯顿的普朗克固体化学物理机构。理论工作在赖斯大学和位于中国北京的人民大学进行。

试验经过迈斯纳研究所的 Erwin Schuberth的视察，普朗克研究所的 Frank Steglich也是第一个看到YRS在量子临界点上的表现的。慕尼黑大学的 Schuberth被两个研究所同时委任的，他说表现质量有增加的现象实际上是核力正在运转的一个线索。

“没有什么可以解释这样大的一个改变，”他说。大部分的试验都在加尔兴进行，在这里 Schuberth的团队使用“绝热地磁冷却法”和其它专业技术，

来使它的YRS样本进入超冷状态，并要比在从前的YRS试验中的低 10倍。这为这个团队发现超导电性创造了条件。

在对这个证据分析的过程中，Si和同事人民大学理论学家 Rong Yu发现在 YRS复合材料中的镱核的惯性旋转的排列会有助于产生超导电性。他说核自旋在及低温下会变成双倍，并排成一种可以暴露出电子的量子临界的有序的形式

“在 YRS中，电子的旋转被锁在一种在空间中周期性变化的模式中，并且是被称为反铁磁性的电子顺序的特性，”Si说。“核自旋的有序排列表现出抑制电子顺序，这就暴露了电子的量子临界，反过来就促进了非常规的超导电性。”

对YRS中的超导电性的发现已经被寻找了超过 10年了。Steglich称从前的试验解释了 YRS中的量子临界将电子带向定位和流动两者的边缘，这种现象在一个 2001年里程碑式的理论中被 Si和他的同事预测过。

Steglich说：“在过去的试验中，一个外部磁场用真正显著的电子特性的集合揭示了量子临界点，这些特性之前已经得到过理论的预测了。但是这种磁场也为超导电性创造了一种贫瘠的环境。

现在的工作已经成功通过在超低温下的核自旋的排序达到量子临界来发现超导电性，不需要使用外部磁场。

“让核自旋在零磁场的情况下产生量子临界并实现超导电性是非常卓越的，”Steglich说。Si说新的发现对于重费密子超导电性和通常而言的量子临界的物理性研究是非常重要的。 “这项研究显示量子临界在引起非常规超导电性方面是一个可靠的机械装置，不仅是在早先已经显示

的高温超导电性中，也包括在每个其它方面的量子临界状态的标准样例的重费密子材料中，”Si说。研究的共同作者包括迈斯纳研究所的Marc Tippmann、迈斯纳研究所和普朗克固体化学物理研究所的Lucia Steinke、Stefan Lausberg,、Alexander Steppke、 Manuel Brando 、Christoph Geibel、普朗克固体化学

物理研究所的所有人员和法兰克福大学和普朗克固体化学物理研究所的 Cornelius Krellner。这项研究由德国研究基金会、Robert A. Welch基金会和，美国国家科学基金会支持。来源：赖斯大学

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Nanosheet growth technique could revolutionize nanomaterial production

The new nanoscale manufacturing process draws zinc to the surface of a liquid, where it forms sheets just a few atoms thick. CREDIT Xudong Wang

After six years of painstaking effort, a group of University of Wisconsin-Madison materials scientists believe the tiny sheets of the semiconductor zinc oxide they're growing could have huge implications for the future of a host of electronic and biomedical devices.

The group -- led by Xudong Wang, a UW-Madison professor of materials science and engineering, and postdoctoral researcher Fei Wang -- has developed a technique for creating nearly two-dimensional sheets of compounds that do not naturally form such thin materials. It is the first time such a technique has been successful.

The researchers described their findings in the journal Nature Communications on Jan. 20.

Essentially the microscopic equivalent of a single sheet of paper, a 2-D nanosheet is a material just a few atoms thick. Nanomaterials have unique electronic and chemical properties compared to identically composed materials at larger, conventional scales.

"What's nice with a 2-D nanomaterial is that because it's a sheet, it's much easier for us to manipulate compared to other types of nanomaterials," says Xudong Wang.

Until now, materials scientists were limited to working with naturally occurring 2-D nanosheets. These natural 2-D structures include graphene, a single layer of graphite, and a limited number of other compounds.

Developing a reliable method to synthesize and manufacture 2-D nanosheets from other materials has been a goal of materials researchers and the nanotechnology industry for years.

In their technique, the UW-Madison team applied a specially formulated surfactant -- a detergent-like substance -- onto the surface of a liquid containing zinc ions.

Due to its chemical properties, the surfactant assembles itself into a single layer at the surface of the liquid, with negatively charged sulfate ions pointed in the direction of the liquid. Those sulfate ions draw the positively charged zinc ions from within the liquid to the surface, and within a couple hours enough zinc ions are drawn up

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to form continuous zinc oxide nanosheets only a few atomic layers thick.

Xudong Wang first had the idea for using a surfactant to grow nanosheets during a lecture he was giving in a course on nanotechnology in 2009.

"The course includes a lecture about self-assembly of monolayers," he says. "Under the correct conditions, a surfactant will self-assemble to form a monolayer. This is a well-known process that I teach in class. So while teaching this, I wondered why we wouldn't be able to reverse this method and use the surfactant monolayer first to grow the crystalline face."

After five years of trial and error with different surfactant solutions, the idea paid off.

"We are very excited about this," says Xudong Wang. "This is definitely a new way to fabricate 2-D nanosheets, and it has great potential for different materials and for many different applications."

Already, the researchers have found that the 2-D zinc oxide nanosheets they've grown are able to function as semiconductor transistors called a p-type, the opposite electronic behavior of naturally occurring zinc oxide. Researchers have for some time attempted to produce zinc oxide with reliable p-type semiconductor properties.

Zinc oxide is a very useful component of electronic materials, and the new nanosheets have potential for use in sensors, transducers and optical devices.

But the zinc oxide nanosheets are only the first of what could be a revolution in 2-D nanomaterials. Already, the UW-Madison team is applying its surfactant method to growing 2-D nanosheets of gold and palladium, and the technique holds promise for growing nanosheets from all sorts of metals that wouldn't form them naturally.

"It brings a lot of new functional material to this 2-D material category," Wang says.

纳米薄片生成技术会革命化纳米材料的产品

新型纳米级制造工艺将锌镀在一种液体的表面，在此它组成了仅仅只有几个原子厚的薄片。资料来源：Xudong Wang

经过六年的辛苦努力，美国威斯康辛材料的一个组的科学家相信他们正在生成的半导体氧化锌薄片在电子和生物医学设备有着巨大的应用。

这个组由麦迪逊大学的材料科学核工程教授 Xudong Wang带头，博士后 Fei Wang已经研发了一种制作接近二维的复合材料的技术，这种复合材料不是自然地组成了这种薄材料。这种技术是首次取得成功。13


研究者将他们的发现描述在 1月 20日的《自然通讯》上。本质上，这种微观上等同于一张纸的二维纳米薄片是一种仅仅几个原子厚的材料。相比相同的更大的

复合材料，纳米材料有着独特的电子和化学特性。 “二维纳米材料好的地方在于它是一种薄片，相比其它纳米材料这更容易让我们操作，”Xudong

Wang说。到现在为止，材料科学家在使用自然产生的二维纳米薄片时受到了限制。这些自然的二维结构包括石

墨烯，即单层石墨，以及有限数量的其他化合物。在很多年里，研发一种可靠的工具来从其它材料合成和制造二维纳米薄片成为材料研究者和纳米技

术产业的目标。在他们的技术中，麦迪逊大学的团队使用了一种特殊的按配方制成的表面活性剂，这是一种类似物

质的清洁剂，将它涂到包含锌离子的液体表面。由于它的化学特性，利用被指向液体的方向的带阴电荷的硫酸盐离子，这种活性剂自己在液体的表

面聚合成一个单层。这种硫酸盐离子将确定的带电锌离子从液体内部到表面吸引出来，两个小时之内足够的锌离子会被吸出来组建持续的氧化锌纳米薄片，这种薄片仅有几个原子层那么薄。

Xudong Wang第一次想到使用表面活性剂来生成纳米薄片是在一次演讲中，在 2009年当时他正在讲授一节关于纳米技术的课。

“这节课包括一场关于单层自组装的演讲，”他说。“在正确的情况下，一个活性剂会进行自我组装来组成一个单层。这是我在课上讲到的一个非常著名的过程。因此当我正在教这个的时候，我在想为什么我们不能颠倒这种方法，并首先使用表面活性剂单层来生成透明面。”

经过五年的利用不同活性剂方案的反复尝试，这种想法终于获得成效了。“我们对此感到非常兴奋，”Xudong Wang说。“这是一个很明确的能制造二维纳米薄片的方式，并

且对于不同的材料和很多不同的应用都有很大的潜力。早先，研究者们已经发现他们生成的二维氧化锌纳米片能够作为半导体晶体管发挥作用，这种半导

体晶体管被称为 p型，是自然发生的氧化锌相反的电子特性。研究者已经有一段时间想要用可信的 p型半导体性能产生氧化锌。

氧化锌是一种非常有用电子材料成分，新的纳米薄片有潜力用在传感器、变频器和光学元件上。但是氧化锌纳米薄片仅仅是第一个在二维纳米材料方面的革命。早先，麦迪逊大学的团队正在用它的

表面活性剂方法生成金和钯的二维纳米薄片，并且这种技术有希望从各种金属中生成纳米薄片，这些金属不会自然地形成这些纳米薄片。“它为二维材料种类带来了很多新的功能材料，”Wang说。

Metal Alloy（金属合金）Metal powders may offer alternative to fossil fuels

The use of metal powders to power external combustion engines could offer a viable alternative to the use of fossil fuels, according to researchers at Canada’s McGill University in Montréal, Québec. In a study published in the journal Applied Energy, the energy and power densities of the proposed metal fuelled zero carbon heat engines are predicted to be close to current fossil fuelled internal combustion engines, making them an attractive technology for a future low carbon society.

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“Technologies to generate clean electricity – primarily solar and wind power – are being developed rapidly; but we can’t use that electricity for many of the things that oil and gas are used for today, such as transportation and global energy trade,” states the lead author of the study, Professor Jeffrey Bergthorson, a mechanical engineering professor and Associate Director of the Trottier Institute for Sustainability in Engineering and Design at McGill University.

When burned, metal powders react with air to form stable, nontoxic solid-oxide products that can be collected relatively easily for recycling, unlike the CO2 emissions from burning fossil fuels that escape into the atmosphere, state the researchers. Iron powder could be the primary candidate for this purpose, according to the study, as it is readily recyclable with well-established technologies and some novel techniques can avoid the carbon dioxide emissions associated with traditional iron production using coal.

“Biofuels can be part of the solution, but won’t be able to satisfy all the demand; hydrogen requires big, heavy fuel tanks and is explosive, and batteries are too bulky and don’t store enough energy for many applications,” stated Bergthorson. “Using metal powders as recyclable fuels that store clean primary energy for later use is a very promising alternative solution.”

Unlike the internal-combustion engines used in gasoline-powered cars, external-combustion engines use heat from an outside source to drive an engine. External-combustion engines, modern versions of coal fired steam locomotives, are widely used to generate power from nuclear, coal or biomass fuels in power stations.

While laboratory work at McGill and elsewhere has shown that the use of metal fuels with heat engines is technically feasible, no one has yet demonstrated the idea in practice. The next step toward turning the laboratory findings into usable technology, therefore, will be “to build a prototype burner and couple it to a heat engine,” added Bergthorson.

金属粉末能够为化石燃料提供替代品据加拿大魁北克省蒙特利尔麦吉尔大学的研究人员称，利用金属粉末来驱动外部燃烧发动机可能会

为化石燃料的使用提供一个可行的替代品。在一项发表于《应用能源》杂志的研究中，提议的金属的能量和功率密度燃料零碳热力发动机预计将接近于目前的化石燃料内燃机，这令它们成为了未来低碳社会中一个具有吸引力的技术。

“产生清洁电力的技术——主要是太阳能和风力发电——将得到迅速发展；但是我们不能将该电力用于许多目前石油和天然气所应用的事物，”该研究的主要作者，麦吉尔大学特罗蒂尔工程与设计可持续发展研究所的副教授兼机械工程学教授杰弗里•波瑟森博士表示。

研究人员声称，在燃烧时，金属粉末与空气发生反应，形成稳定的非毒性固体氧化产物，其能够得到轻易地收集进行循环利用，而不像燃烧化石燃料所产生的二氧化碳排放物，其逃逸到大气中。据该研究显示，铁粉可能会成为该目的的主要候选物，因为它易于通过成熟的技术得到回收利用，并且一些新的技术能够避免与传统的使用煤炭所产生的铁产物相关的二氧化碳排放物。

“生物燃料可能成为该解决方案中的一部分，但是其不可能满足所有的需求；氢需要又大又重的燃料箱并且具有爆炸性，而电池太笨重并且存储不了用于许多应用的足够能量，”波瑟森声称。“利用金属粉末作为存储之后使用的清洁性原始能量的可回收利用的燃料是一种非常有前途的替代性解决方案。”

不像是汽油动力型汽车中所使用的内燃机，外部燃烧发动机使用来自外部资源的热量来驱动发动机。外部燃烧发动机，燃煤蒸汽机车的现代版本，被广泛应用于利用发电站的核、煤或生物质燃料来产生动力。15


虽然在麦克吉尔及其他地方的实验室研究已经表明，通过热力发动机使用金属燃料在技术上是可行的，但是目前还没有人在实践中证实过这个想法。下一步是将实验室的结果转化为可用的技术，因此，那将会是“建立一个原型燃烧器并且将其与热力发动机相耦合，”波瑟森补充称。

Composite Materials（复合材料）Hexcel’s Carbon Fibre Composites Benefit Latest Premium Car Model

Hexcel’s CFRP technology has been introduced in the BMW 7 Series where it is used to save weight and reinforce the metal shell of the B-pillar.

Hexcel explains that it supplies BMW with preforms made of unidirectional carbon prepreg set in various orientations and combined with adhesive. The prepreg is made from Hexcel’s HexPly M77 resin system that cures in 1.5 minutes at 160°C.

To meet the requirements for series production in the automotive industry, Hexcel says it has installed a fully automated production line in Austria that converts unidirectional prepreg into bidirectional preforms in seconds. The process allows prepreg plies of different weights and orientation to be combined in the same ply-book and includes automated cutting, camera-assisted ply positioning, integration of adhesive and automated packing.

According to Hexcel, this unique, fully-automated production cell makes B-pillar preforms for up to 500 cars each day allowing them to meet the high production rates required by automotive manufacturers and the high quality expectations of premium car manufacturers.

赫氏公司的碳纤维复合材料有益于最新的高档车型赫氏公司的碳纤维复合材料已经被引进到 BMW 7系列，在此它被用来减轻重量和加强中立柱的金属

外壳。赫氏公司解释说它为宝马公司提供了设立在各个方向用粘合剂结合的焊料预成型，这种焊料预成型

是由单向性碳半固化片组成的。为了满足汽车行业中系列产品的需求，赫氏公司称它已经在澳大利亚安装了一套全自动生产线，它

在短时间内把单向性半固化片转换成双向性半固化片。这个工艺允许不同重量和方向的半固化片板层在同样的板层集中结合，包括自动化切割，摄像头辅助的板层定位，粘合剂和自动化包装的集合。

根据赫氏公司解释，这项独特的全自动化生产单元使中立柱焊料预成型能满足每天 500辆车的需求使它们能够满足汽车生产商要求的高效的生产率和对高档汽车的高质量预期。

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Toho Tenax Develops Energy-saving, High-productivity Carbonising Process and Surface Treatment Technologies

Toho Tenax has developed technologies for innovative microwave carbonisation and plasma surface treatment, which are expected to help energy and CO2 emissions saving production of automobiles, high-speed railcars and aircrafts through increased use of carbon fibre reinforced plastic (CFRP).

Toho Tenax explains that it is now working to commercialise the technologies for mass production in the coming future, when CFRP is expected to be used on an increasingly large scale. For CFRP solutions broadly incorporating everything from raw materials to composite materials, the company has been placing a special emphasis on reducing production-use energy and CO2 emissions by 50% while dramatically improving productivity.

Toho Tenax says that by using the world’s first application of microwave energy carbonisation under atmospheric pressure it has achieved a tensile modulus of 240 GPa or greater and rupture elongation of 1.5% or greater, both equivalent to levels found in industrial products. The advanced carbonising process was developed by examining the fibre- structure formation process when carbonising a bundle of between 12,000 and 24,000 pieces of flame-resistant oxidised PAN fibres, and then developing the most appropriate microwave processing method to carbonise this fibrous material. Using direct heating with microwave energy, fibrous material is carbonised continuously without having to maintain a high-temperature oven, thereby saving time and energy.

Toho Tenax adds, it has also succeeded in developing a carbon fibre ultra-fast plasma surface treatment technology using dry process. The highly simplified process reduces energy consumption by 50% for the whole process, compared to the conventional carbon fibre production process. In addition, the ultra-fast treatment improves the adhesiveness of carbon fibre and matrix resin.

Carbon fibre applications are expanding beyond aerospace into fields including automobiles, the environment, energy and infrastructure. However, Toho Tenax claims the carbonising process in the carbon fibre manufacturing process consumes large amounts of energy and produces CO2 emissions, so reductions in these areas are urgently required to facilitate large-scale mass production for automobiles and other applications.

Toho Tenax’s research and development programs were implemented by Japan’s New Energy and Industrial Technology Development Organisation (NEDO). NEDO says it began promoting the research and development of innovative materials and technologies in 2014. One of the core themes of this initiative has been the research and development of core technologies for innovative carbon fibre mass-production processes for inventive CFRP applications. Toho Tenax has been participating in the project from the early stage.

东邦特耐克斯公司研发了节能高生产力的碳化工艺和表面处理技术东邦特耐克斯公司研发了革新的微波碳化和等离子表面处理技术，有望通过碳纤维增强塑料

（CFRP）的使用帮助汽车、高速轨道车和飞行器的能源和二氧化碳的节约产品。东邦特耐克斯解释说它现在正致力于将此项技术商业化，从而在不远的将来能够进行大量生产，那

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时 CFRP将会被更多范围的使用。由于 CFRP解决方案广泛地将从原材料到复合材料之间的所有东西进行合并，这个公司特别强调在彻底改善生产力的同时将生产使用的能源和二氧化碳排放都降低 50%。

东邦特耐克斯公司称通过利用世界第一批在大气压下对微波能量碳化的应用，它的拉伸模量已经达到 240 GPa或者以上，断裂拉伸达到 1.5%或者以上，这两种都和目前在工业产品发现的水平等同。这种先进的碳化工艺通过检测纤维结构形成工艺得到发展，这个工艺需要碳化 12000到 24000片之间的一束耐火氧化的 PAN纤维，然后研发最合适的微波处理方法来碳化这个纤维材料。利用微波能量进行直接加热，纤维材料在不需要保持高温熔炉的情况下被持续碳化，因此节省了时间和能源。

东邦特耐克斯公司补充道，它在利用干燥工艺开发一种碳纤维超快等离子表面处理技术上也取得了成功。相比传统的碳纤维生产工艺，这个高度简化的工艺在整个过程中减少了 50%的能源消耗。除此以外，这种超快处理也改善了碳纤维和基体树脂的黏合性。

碳纤维应用正在由航空航天扩大到汽车行业、环境、能源和基础设施领域。然而，东邦特奈克斯公司称在碳纤维制造工艺中的碳化工艺消耗了大量的能源，并有二氧化碳排放，在这些领域的减少对于促进汽车和其他应用大规模生产是十分迫切的。

东邦特耐克斯的研究和开发项目被日本的新能源和工业技术开发组织（NEDO）所实施了。NEDO称它在 2014年开始促进这种革新材料的研究和开发。这个主动权的核心主题之一是为发明的碳纤维复合材料的革新碳纤维大批量生产工艺的研究与开发。东邦特奈耐克斯在早期已经参与进这个项目中去了。

GKN Aerospace Delivers Innovative Clean Sky Wing Structure

GKN Aerospace has delivered innovative wing components as part of a major research programme to test and measure the benefits of‘natural laminar flow’(NLF)designs during trials on the wing of a flight test aircraft.

According to GKN,the Breakthrough Laminar Aircraft Demonstrator in Europe(BLADE)project is part of the Clean Sky Smart Fixed Wing Aircraft(SWFA)programme,an extensive,50%European Union-funded,multi-partner activity aimed at lowering fuel consumption and emissions by reducing aircraft drag.

GKN Aerospace has delivered the assemblies and upper covers that form part of the NLF wing section on the starboard wing of the Airbus A340 flight test aircraft.It claims that these structures offer NLF levels of performance through the adoption of a totally new design approach and the application of novel manufacturing technologies that deliver the ultra-high tolerances and exceptional surface finish required.

During flight tests,taking place in 2017,this wing section will be used to test the performance characteristics of NLF wing architecture,helping prove predicted economic and environmental benefits:An NLF wing is expected to reduce wing drag by 8%and improve fuel consumption by approaching 5%.

Russ Dunn,Senior Vice President,Engineering and Technology at GKN Aerospace explains,“The SFWA BLADE programme is allowing us to progress innovative technologies,concepts and capabilities with the potential to bring about a step change in aircraft fuel consumption.”

Dunn continues,“The key challenge with designing and manufacturing an NLF wing,with the many aerodynamic benefits that promises,stems from the need to tightly control the wing surface.It is vital to eliminate features such as steps,gaps,surface roughness and waviness or fastener heads as these all lead to more traditional‘turbulent

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flow’performance levels.The GKN Aerospace team has created these integrated,co-cured composite upper covers and very high tolerance leading edge surfaces using the same structured design and development process applied in commercial aircraft programmes.As a result,our first part was of very high quality and has been delivered for the flight test programme-which for such an innovative structure was a huge achievement for the entire team.”

GKN航宇公司推出了创新型清洁天空机翼结构GKN航宇公司已经推出了创新型机翼部件作为一项主要研究计划的一部分，用于测试及测量“自然

层流”（NLF）设计在机翼的飞行试验试飞测试中的好处。据GKN表示，欧洲突破层流飞机验证机（BLADE）项目是清洁天空智能固定翼飞机（SWFA）计划

的一部分，是一个广泛的拥有 50%的欧洲资助的多伙伴活动，其目的是通过减少飞机的阻力来降低油耗及排放量。

GKN航宇公司已经交付了形成空客A340试飞飞机右翼上NLF机翼段一部分的组件及上盖。其声称，这些结构通过采用能够提供所需的超高容差和出色的表面光洁度的全新设计方法及新的制造技术，表现出NFL的性能水平。

在即将于 2017年进行的飞行试验中，该机翼段将被用于测试 NLF机翼结构的性能特点，帮助证实预测的经济和环境效益：NLF机翼预计会减少 8%的机翼阻力，并且提高将近 5%的燃油消耗。

GKN航宇公司的工程和技术部高级副总裁拉斯•邓恩解释称：“SFWA BLADE项目令我们能够发展出具有为飞机燃油消耗带来阶跃变化潜能的创新技术、理论和能力。”邓恩继续表示，“设计和制造具有所承诺的许多空气动力学好处的 NLF机翼所面临的主要挑战源自于对严格控制翼面的需求。这对于消除一些特性至关重要，这些特性包括台阶、缺口、表面粗糙度以及紧固件头部的波动，因为所有这些都会产生更多传统性的‘湍流’性能水平。GKN航宇公司的团队已经通过利用商用飞机项目所采用的相同结构设计和开发过程创造出这些集成的共固化复合上盖及能够产生非常高的耐受性的边缘表面。这样一来，我们的第一个部分具有非常高的质量，并且已经提供用于试飞计划——而该计划对于这样一个创新结构来说对于整个团队都是一个巨大的成就。”

Building a Specialist Pilot Plant for the Production of High Value Nano-structured Powders

Building a Specialist Pilot Plant for the Production of High Value Nano-structured Powders

The Centre for Process Innovation (CPI) and nine other European partners are collaborating in the design, scale-up and build of a high energy ball-mill (HEBM) pilot plant for the production and validation of innovative nanostructured powders.

According to CPI, these advanced powders will be able to be used in a number of high value manufacturing applications such as cutting tools, medical implants and a range of aerospace and automotive components. It explains that the work is part of a four-year European research and development project titled ‘PilotManu’ which began in 2013 and is due for completion in September 2017. The project is well underway and has already experienced excellent results regarding the performance of the advanced powders for use in abrasive tools and the development of the pilot plant.

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The €5.3 million project, which is partially funded by European Union’s Framework Programme Seven (FP7), involves ten partner organisations across seven countries, bringing together various capabilities such as process engineering, materials investigation, product development and prototyping, characterisation, application testing and process economics. The project partners include CPI alongside MBN Nanomaterialia, IMDEA Materials Institute, +90, Putzier, INOP, Manudirect, IMPACT INNOVATIONS, Matres and Diam Edil.

PilotManu is manufacturing the nanostructured powders using a proprietary high energy ball milling technology developed by lead partner MBN Nanomaterialia. The technology will allow for the manufacture of innovative advanced powders with ultrafine crystalline structures, meaning that products can be optimised to enhanced strength, reduce weight or provide excellent wear, corrosion or thermal resistance. The achievements from the project will create a number of new product opportunities in not only the automotive and aerospace sectors but also in other high value markets such as healthcare and energy amongst others.

However, currently low productivity and high material costs remain a major barrier for the commercialisation of advanced powders that are manufactured by high energy ball milling techniques. PilotManu is working to remove this barrier by scaling-up the manufacturing process and improving production efficiencies.

Commenting on the project, Dr Charanjeet Singh, Innovation Manager at CPI adds, “We are delighted with the progress of the PilotManu project so far. The consortium has been able to design and scale-up the manufacturing process. The pilot plant will come online in the next few months and we anticipate the production of some truly innovative powders which will be validated for their suitability and performance in a number of value adding applications.

CPI explains that both the pilot plant and the associated products developed by the consortium will significantly reduce the current productivity and cost barriers that are in the way of the market adoption of advanced powders. Once concluded, the consortium will demonstrate the technological and economical viability of the pilot line by incorporating the powders into advanced materials targeted at a number of applications such as wear resistant coatings, abrasive tools and additive manufacturing applications. The nano-scale features of these materials will allow for significant improvements in material performance such as physical-chemical-mechanical properties compared against bulk scale materials.”

Project Co-ordinator, Prof. Paolo Matteazzi from MBN Nanomaterialia adds, “We expect that the High Energy Ball Milling pilot plant being developed in the PilotManu project will enable MBN Nanomaterialia to overcome the productivity and cost barriers that are currently preventing the commercialisation of the advanced nanomaterials.The new pilot manufacturing line, based on the upscaling of a current HEBM facility, will increase production by ten times and allow us to enter the market for three main lines of innovative products and technologies; the diamond tool industry, CerMet and alloys for wear resistant coatings and new mechanical alloyed composites for additive manufacturing. Beside applications being developed in the project, the new pilot line will allow us to exploit the potential of advanced materials synthesised by HEBM in additional areas such as energy harvesting materials using high temperature thermoelectrics, metal hydrides for energy storage and high temperature ODS alloys for fossil energy application and also nano-composite polymers for functional textiles and packaging.”

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为高价值的纳米材料粉剂建造专业的试验工厂为高价值的纳米材料粉剂建造专业的试验工厂。工艺革新中心（CPI）和另外九个欧洲合作者正在为创新纳米材料粉末的生产和批准共同进行设计、

扩展和建造一所高能量球磨机(HEBM)试验工厂。根据 CPI所言，这种先进的粉剂将能够被应用于大量高价值的制造业应用中，如切割工具、医疗植

入、、航空航天系列和自动化元件。它解释说这项工作是一项名为‘PilotManu’的为期 4年的欧洲研发项目的一部分。这个项目开始于 2013年，将在 2017年 9月结束。这个项目经过良好的起步，已经在先进粉末在磨料工具和试验工厂的发展应用的效果方面取得卓越的成果。

这个 530万欧元项目的资金部分由欧盟第七框架项目提供，同时涉及七个国家的十个合作组织，将如工艺工程、材料研发、产品开发和样机研究、特性描述、应有测试和工艺经济学等各种各样的性能联合在了一起。这个项目的合作者包括与 CPI 并肩的 MBN Nanomaterialia 、 IMDEA 材料所、+90、Putzier,、INOP、Manudirect、 IMPACT INNOVATIONS 、Matres 和Diam Edil。

PilotManu正在利用专利的高能球磨碾磨技术制造这种纳米结构的粉剂，这种技术是由领头合作研发者MBN Nanomaterialia研发。这种技术将允许带有超细结晶结构的革新先进粉末的制造，这就意味着实现最优化来加强力量、减少重量或者提供卓越的耐久性、腐蚀和热阻。出自这个项目的成果将给不仅是汽车行业和航天技术带来机会，也给其他如医疗保健和其他如能源之类的高价值市场创造大量新的产品机遇。

然而，现在低生产力和高材料成本仍然成为通过高能量球磨碾磨技术制造的先进粉剂商业化的主要障碍。PilotManu正在致力于放大产品制造过程和改善生产效率来移除这一障碍物。

CPI的革新经理 Charanjeet Singh博士在评论这个项目时补充道：“我们很为这项 PilotManu项目目前为止的成就感到开心。联盟已经有能力设计和加大制造进度了。试验工厂将在接下来几个月上线，我们分析了一些真正革新的粉剂的产品，这些粉剂在许多增值的应用中的适用性和性能已经得到了证实。

CPI解释道，联盟的试验工厂和有关产品开发将会大大降低现在的生产力和成本障碍，这些障碍出现在市场对先进粉剂的应用道路上。曾经总结说道：联盟将会通过将粉剂与先进材料合并来说明试产线在技术上和经济上的可行性。目标旨在如耐磨涂层、磨具和添加剂制造应用的大量应用中。相比大体积的材料，这种材料纳米级尺度的特性将在如物理、化学和机械学特性的材料性能中产生重大的改善。

来自MBN Nanomaterialia的项目协调人 Paolo教授补充道：“我们希望正在开发的 PilotManu项目中的高能量球磨碾磨试验工厂将使MBN Nanomaterialia能够克服当下正在阻碍先进纳米材料商业化的生产力和成本方面的障碍。新的试制线建立在一个当前的HEBM基础设施的扩展上，将会增加十倍，并允许我们进入革新产品和技术的三个主线的市场中；金刚石刀具、金属陶瓷和合金用于耐磨涂层，新型机械合金复合材料用于添加剂制造业。除了在这个项目中开发的应用，新的试制线允许我们探索在别的领域由HEBM合成的先进材料的潜在能力，如使用高温热电的能量采集材料，用于能源储存的金属氰化物材料，用于化石能源应用的高温ODS合金，以及用作功能纺织面料和包装的纳米复合高分子。

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Practical Application（实际应用）For this nanocatalyst reaction, one atom makes a big difference

This simulation shows a 10-atom platinum cluster that catalyzed the ethylene reaction. Credit: Georgia Tech

Combining experimental investigations and theoretical simulations, researchers have explained why platinum nanoclusters of a specific size range facilitate the hydrogenation reaction used to produce ethane from ethylene. The research offers new insights into the role of cluster shapes in catalyzing reactions at the nanoscale, and could help materials scientists optimize nanocatalysts for a broad class of other reactions.

At the macro-scale, the conversion of ethylene has long been considered among the reactions insensitive to the structure of the catalyst used. However, by examining reactions catalyzed by platinum clusters containing between 9 and 15 atoms, researchers in Germany and the United States found that at the nanoscale, that's no longer true. The shape of nanoscale clusters, they found, can dramatically affect reaction efficiency.

While the study investigated only platinum nanoclusters and the ethylene reaction, the fundamental principles may apply to other catalysts and reactions, demonstrating how materials at the very smallest size scales can provide different properties than the same material in bulk quantities. Supported by the Air Force Office of Scientific Research and the Department of Energy, the research will be reported January 28 in the journal Nature Communications.

"We have re-examined the validity of a very fundamental concept on a very fundamental reaction," said Uzi Landman, a Regents' Professor and F.E. Callaway Chair in the School of Physics at the Georgia Institute of Technology. "We found that in the ultra-small catalyst range, on the order of a nanometer in size, old concepts don't hold. New types of reactivity can occur because of changes in one or two atoms of a cluster at the nanoscale."

The widely-used conversion process actually involves two separate reactions: (1) dissociation of H2 molecules into single hydrogen atoms, and (2) their addition to the ethylene, which involves conversion of a double bond into a single bond. In addition to producing ethane, the reaction can also take an alternative route that leads to the

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production of ethylidene, which poisons the catalyst and prevents further reaction.

The project began with Professor Ueli Heiz and researchers in his group at the Technical University of Munich experimentally examining reaction rates for clusters containing 9, 10, 11, 12 or 13 platinum atoms that had been placed atop a magnesium oxide substrate. The 9-atom nanoclusters failed to produce a significant reaction, while larger clusters catalyzed the ethylene hydrogenation reaction with increasingly better efficiency. The best reaction occurred with 13-atom clusters.

Bokwon Yoon, a research scientist in Georgia Tech's Center for Computational Materials Science, and Landman, the center's director, then used large-scale first-principles quantum mechanical simulations to understand how the size of the clusters - and their shape - affected the reactivity. Using their simulations, they discovered that the 9-atom cluster resembled a symmetrical "hut," while the larger clusters had bulges that served to concentrate electrical charges from the substrate.

"That one atom changes the whole activity of the catalyst," Landman said. "We found that the extra atom operates like a lightning rod. The distribution of the excess charge from the substrate helps facilitate the reaction. Platinum 9 has a compact shape that doesn't facilitate the reaction, but adding just one atom changes everything."

Nanoclusters with 13 atoms provided the maximum reactivity because the additional atoms shift the structure in a phenomena Landman calls "fluxionality." This structural adjustment has also been noted in earlier work of these two research groups, in studies of clusters of gold which are used in other catalytic reactions.

"Dynamic fluxionality is the ability of the cluster to distort its structure to accommodate the reactants to actually enhance reactivity," he explained. "Only very small aggregates of metal can show such behavior, which mimics a biochemical enzyme."

The simulations showed that catalyst poisoning also varies with cluster size - and temperature. The 10-atom clusters can be poisoned at room temperature, while the 13-atom clusters are poisoned only at higher temperatures, helping to account for their improved reactivity.

"Small really is different," said Landman. "Once you get into this size regime, the old rules of structure sensitivity and structure insensitivity must be assessed for their continued validity. It's not a question anymore of surface-to-volume ratio because everything is on the surface in these very small clusters."

While the project examined only one reaction and one type of catalyst, the principles governing nanoscale catalysis - and the importance of re-examining traditional expectations - likely apply to a broad range of reactions catalyzed by nanoclusters at the smallest size scale. Such nanocatalysts are becoming more attractive as a means of conserving supplies of costly platinum.

"It's a much richer world at the nanoscale than at the macroscopic scale," added Landman. "These are very important messages for materials scientists and chemists who wish to design catalysts for new purposes, because the capabilities can be very different."

Along with the experimental surface characterization and reactivity measurements, the first-principles theoretical simulations provide a unique practical means for examining these structural and electronic issues because the clusters are too small to be seen with sufficient resolution using most electron microscopy techniques or traditional crystallography.

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"We have looked at how the number of atoms dictates the geometrical structure of the cluster catalysts on the surface and how this geometrical structure is associated with electronic properties that bring about chemical bonding characteristics that enhance the reactions," Landman added.

Source: Georgia Institute of Technology

由于纳米催化剂的反应，一个原子会产生重大影响

这项模拟显示一簇 10个原子组成的铂催化了乙烯反应。出处：乔治亚理工学院将实验研究和理论模拟相结合，研究者们解释了为什么特定粒度范围的铂簇会促进从乙烯中制出乙

烷的加氢反应。这个研究为观察簇的角色在纳米级下使催化反应成形提供了新的视角，并帮助材料科学家在不同级别的其它的反应中使纳米催化剂最优化。

在宏观尺度下，乙烯的转化被长期视为在反应中对于使用的催化剂是不敏感的。通过检验由包含 9到15个原子的铂簇催化的反应，德国和美国的研究者们发现在纳米级下，这不再是正确的。他们发现纳米簇的形状可以彻底影响反应的效率。

然而这个研究仅仅调查了铂纳米簇和乙烯反应，这个基本的原则也许适用于其它的催化剂和反应，说明相比最小尺度的材料，同种更大数量的材料是如何提供不同的性能。这项研究由科学研究空军办公室和能源部支持进行，将会在 1月 28日在《自然通讯》杂志上报告出来。

“我们在非常基础的反应中重新检验了非常基础的概念的有效性，”瑞金大学的教授和乔治亚技术机构的物理学院 F.E. Callaway主席Uzi Landman说：“我们发现在极小的催化剂范围内，在尺寸上属于同类的毫微米，旧概念并不能保持下去。由于纳米级下一簇的一两个原子的改变，新的类型的反应也会发生。”

这个广泛使用的转化进程实际上涉及两个单独的反应：1）H2分子分离成单一的氢原子；2）它们对于乙烯的增加，包括将双键转化成单键。除了生成乙烷之外，反应也采取了交替的路径使亚乙基得以生成，这破坏了催化剂从而组阻止了进一步的反应。

这项研究由 Ueli Heiz教授和他组中来自慕尼黑工业大学的研究员们发起，以试验的方式测验簇的反应率，这些簇包含了 9、10、11、12、或者 13个放置在一个氧化镁基片顶部的铂原子。9个原子的纳米簇不能产生有意义的反应，然而随着不断变高的效率更大的簇催化了乙烯的加氢反应。最好的反应是在包含 13个原子的簇下产生。

乔治亚理工学院计算材料科学中心的研究科学家 Bokwon Yoon和这个中心的主管 Landman在之后利用大比例尺的第一性原理量子力学模拟来理解簇的大小和形状是如何影响反应的。使用他们模拟，他们发现 9个原子的簇类似一个对称的“小屋，”然而大点的簇有凸起用于集中来自基片电荷。

“一个原子改变了催化剂的整个活性，”Landman说。“我们发现额外的原子表现的像避雷针一样。来24


自基片的超出电荷的干扰帮助促进了反应。铂 9有着不能促进反应的紧密的形状，但是只增加一个原子就会改变所有情况。”

因为额外的原子改变了在 Landman称之为“流变”的一个现象中的结构，有 13个原子的纳米簇提供了最大化的反应。这个结构性调整已经在这两个研究组的早期工作中被标示出来，就在用于其它催化反应的金簇的研究中。

“动态的流变性是簇用来扭曲它的结构从而调解反应实现真正加强反应的能力，”他解释说。“仅仅非常小的聚合物有这样的表现，这模仿了生物化学的酶。”

这个模拟显示出催化剂中毒也会随着簇的大小和温度而发生变化。10个原子的簇可以在室温下被破坏，而 13个原子的簇只能在更高的温度下才会被破坏，这帮助解释了他们改善的反应。

“小的确实是不同的，“Landman说。”一旦你进入这种尺度的社会制度中，旧有的结构敏感性和结构不敏感性必须因它们持久的有效性而被评估。这再也不是一个表面积和体积比的问题，因为在这些非常小的簇中一切东西都在表面。

但是这个项目仅仅试验了一种反应和一种催化剂，支配纳米级催化剂的原则和重新检验传统预期的重要性或许应用在了广泛的最小尺寸纳米簇催化的反应中。这样的纳米催化剂作为代价高的铂的保存的供应品的一种方法而变得更加有吸引力。

“纳米级下的世界比宏观级别下的世界要富有的多，”Landman补充道。“这对于希望为新用途设计催化剂的材料科学家和化学家来讲是非常重要的信息，因为这些能力是非常不同的。”

连同试验表面特性记述和反应测量值一同，第一性原则理论性模拟为测试这些结构和电力的问题提供了独特的实践工具，因为哪怕在使用大部分的电子显微镜技术或者传统的结晶学的足够的分辨率情况下，簇也因为太小而不能被看到。

“我们已经在审视大量的原子是如何规定表面的簇催化剂的几何结构的，以及这些几何机构是如何和引起化学成键特性的电子特性相联系的，这些化学成键特性是用来加强反应的，”Landman补充道。

来源：乔治亚理工学院

Electric Eel-like Fiber Could Become New Power Source

Material engineered by scientists from Shanghai, China’s Fudan University may someday become a new source of energy for items like wearable devices and solar panels.

The fiber, composed of conductive thread placed on top of a series of carbon nanotube sheets, can emit an electrical pulse in a manner akin to the electric eel, writes Fortune.

This species of eel can produce up to 600 volts of electricity through 6,000 cells that work like small batteries, writes Mental Floss.

As Fortune explains, researchers used these fibers to power a watch stationed on a wristband. The team stitched rows of this material into a T-shirt, which was able to turn on a string of 50 embedded LED lights. An estimated 1,000 volts were produced by stretching the fibers out to nearly 40 feet long.

Currently the fiber can only store energy, not generate it.

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电子鳗状纤维可以成为新动力能源来自中国上海复旦大学设计的材料有一天可能成为像可佩带设备和太阳能板之类项目的新动力能源。这种纤维是由置于一连串碳纳米管片之上的传导线组成的，它可以按电鳗的方式发出一种电子脉冲。

《财富》杂志这样写道。这种电鳗可以通过 6000细胞产生达到 600瓦的电力，就像小型电池一样运作。就像《财富》杂志解释的那样，研究者使用这种纤维来给戴在手腕的手表提供电力。这个团队将这种材

料缝了一排在 T恤上，使它能够打开一串 50个的嵌入式 LED灯。通过拉出将近 40英尺的纤维可以产生预计 100瓦的电力。

现在这种纤维只能储存电力而不能发电。

A nanophotonic comeback for incandescent bulbs?

A proof-of-concept device built by MIT researchers demonstrates the principle of a two-stage process to make incandescent bulbs more efficient. This device already achieves efficiency comparable to some compact fluorescent and LED bulbs. Image: Courtesy of the researchers

Traditional light bulbs, thought to be well on their way to oblivion, may receive a reprieve thanks to a technological breakthrough.

Incandescent lighting and its warm, familiar glow is well over a century old yet survives virtually unchanged in homes around the world.That is changing fast,however,as regulations aimed at improving energy efficiency are phasing out the old bulbs in favor of more efficient compact fluorescent bulbs(CFLs)and newer light-emitting diode bulbs(LEDs).

Incandescent bulbs,commercially developed by Thomas Edison(and still used by cartoonists as the symbol of inventive insight),work by heating a thin tungsten wire to temperatures of around 2,700 degrees Celsius.That hot wire emits what is known as black body radiation,a very broad spectrum of light that provides a warm look and a faithful rendering of all colors in a scene.

But these bulbs have always suffered from one major problem:More than 95 percent of the energy that goes into them is wasted,most of it as heat.That's why country after country has banned or is phasing out the inefficient technology.Now,researchers at MIT and Purdue University may have found a way to change all that.

The new findings are reported in the journal Nature Nanotechnology by three MIT professors--Marin Soljači?,professor of physics;John Joannopoulos,the Francis Wright Davis Professor of physics;and Gang

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Chen,the Carl Richard Soderberg Professor in Power Engineering--as well as MIT research scientist Ivan Celanovic,postdoc Ognjen Ilic,and Purdue physics professor(and MIT alumnus)Peter Bermel PhD'07.

Light recycling

The key is to create a two-stage process,the researchers report.The first stage involves a conventional heated metal filament,with all its attendant losses.But instead of allowing the waste heat to dissipate in the form of infrared radiation,secondary structures surrounding the filament capture this radiation and reflect it back to the filament to be re-absorbed and re-emitted as visible light.These structures,a form of photonic crystal,are made of Earth-abundant elements and can be made using conventional material-deposition technology.

That second step makes a dramatic difference in how efficiently the system converts light into electricity.The efficiency of conventional incandescent lights is between 2 and 3 percent,while that of fluorescents(including CFLs)is currently between 7 and 13 percent,and that of LEDs between 5 and 13 percent.In contrast,the new two-stage incandescents could reach efficiencies as high as 40 percent,the team says.

The first proof-of-concept units made by the team do not yet reach that level,achieving about 6.6 percent efficiency.But even that preliminary result matches the efficiency of some of today's CFLs and LEDs,they point out.And it is already a threefold improvement over the efficiency of today's incandescents.

The team refers to their approach as"light recycling,"says Ilic,since their material takes in the unwanted,useless wavelengths of energy and converts them into the visible light wavelengths that are desired."It recycles the energy that would otherwise be wasted,"says Soljači?.

Bulbs and beyond

One key to their success was designing a photonic crystal that works for a very wide range of wavelengths and angles.The photonic crystal itself is made as a stack of thin layers,deposited on a substrate."When you put together layers,with the right thicknesses and sequence,"Ilic explains,you can get very efficient tuning of how the material interacts with light.In their system,the desired visible wavelengths pass right through the material and on out of the bulb,but the infrared wavelengths get reflected as if from a mirror.They then travel back to the filament,adding more heat that then gets converted to more light.Since only the visible ever gets out,the heat just keeps bouncing back in toward the filament until it finally ends up as visible light.

The technology involved has potential for many other applications besides light bulbs,Soljači?says.The same approach could"have dramatic implications"for the performance of energy-conversion schemes such as thermo-photovoltaics.In a thermo-photovoltaic device,heat from an external source(chemical,solar,etc.)makes a material glow,causing it to emit light that is converted into electricity by a photovoltaic absorber.

"LEDs are great things,and people should be buying them,"Soljači?says."But understanding these basic properties"about the way light,heat,and matter interact and how the light's energy can be more efficiently harnessed"is very important to a wide variety of things."

He adds that" the ability to control thermal emissions is very important. That's the real contribution of this work."As for exactly which other practical applications are most likely to make use of this basic new technology, he says, "it's too early to say."

Source: Massachusetts Institute of Technology

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白炽灯泡中纳米光子的复出？

由MIT（麻省理工学院）的研究人员建造的概念验证的装置展示了再加高效的制造白炽灯光的两阶段过程。该设备已经实现了能够与一些紧凑型荧光灯和 LED灯泡相媲美的效率。图片：承蒙研究人员

被认为即将被遗忘的传统灯泡可能由于技术突破而获得一个死缓。白炽灯的照明以及其温暖、熟悉的光芒在其存在的一个多世纪以来在世界各地的家中几乎没有发生改

变。但是，这正在发生着迅速地变化，因为旨在提高能源利用效率的法规正在逐步淘汰旧灯泡，转而采用更加高效的紧凑型荧光灯（CFLs）以及更新的发光二级管灯泡（LEDs）。

由托马斯•爱迪生商业开发的白炽灯泡（并且仍然被漫画家用作创造性洞察力的象征），是通过将一根细的钨丝加热到 2700摄氏度左右的温度来进行工作的。该热线会发生所谓的黑体辐射，一个非常广泛的光频率，能够提供一个温暖的外观以及在一个场景中表现出各种颜色的忠实呈现。

但是，这些灯泡总是会出现一个主要的问题：超过 95%的进入它们的能量都被浪费掉了，大部分为热量。这就是为什么各个国家相继明令禁止或淘汰这个低效的技术。现在，MIT和普渡大学的研究人员可能已经找到了一种方法来改变这一切。

新的研究结果由三位MIT的教授发表于《自然纳米技术》杂志——物理学教授马林•索杰斯；物理学的弗朗西斯•莱特•戴维斯教授约翰•约诺普洛斯；以及电力工程系卡尔•里查德•索德伯格教授陈刚——以及MIT的研究科学家伊万•卡洛诺维奇，博士后奥格年•伊利奇和普渡大学物理学教授（及MIT校友）彼得•贝梅尔博士’07。

光循环研究人员报告称，关键在于创造一个两阶段的过程。第一阶段涉及了常规加热的金属丝，具有所有其

伴随的损失。但是，不同于令该废热以红外线辐射的形式消散，围绕着灯丝的二级结构将这种辐射捕获，并且将其反射回灯丝以进行再吸收并且再发射为可见光。这些结果是光子晶体的一种形式，是由地球上丰富的元素制成的，并且能够使用常规材料沉积技术来生产。

第二个步骤令该系统将光能转化为电能的有效性产生了显著差异。传统白织灯的效率在 2-3%，而荧光灯（包括 CFLs）目前在 7-13%，并且 LEDs在 5-13%。然而，该小组表示，新的两阶段白炽灯能够实现高达 40%的效率。

由该小组制成的第一个概念验证设备并没有达到这个水平，实现了约 6.6%的效率。但是，他们指出，即便是初次的结果也与今天的一些 CFLs和 LEDs的效率相匹配。并且其已经对目前的白炽灯的效率实现了三倍的改善。

该小组将他们的方法称为“光循环”，伊利奇表示，因为他们的材料吸收了能量中不用的或无用的波长，并且将其转换成需要的可见光波长。“其循环了有可能会浪费掉的能量，”索杰斯表示。

灯泡及超越他们成功的一个关键在于设计了一个能够在很宽的波长和角度范围内起作用的光子晶体。光子晶体本

身是由沉积在衬底上堆叠的薄的层构成的。“当你堆叠这些层时，通过正确的厚度和顺序，”伊利奇解释称，你能够有效地调整材料与光相互作用的方式。在他们的系统中，所希望的可见波长会直接通过该材料

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并且穿过灯泡，但是红外波长会得到反射，就像从镜面反射一样。然后，它们返回灯丝，增加更多的热量，从而转变成更多的光线。由于只有可见光释放，该热量会不断地回到灯丝，直到其最终成为可见光。

所涉及的技术具有用于灯泡以外的许多其他应用的潜能，索杰斯表示。同样的方法可能会对像热光伏电池等能量转换方案的性能“产生显著影响”。在一个热光电装置中，从外部源（化学、太阳能等）获得的热量令一个材料发光，令其发射出由光伏吸收器转变成电力的光。

“LEDs是伟大的事物，并且人们应该购买它们，”索杰斯表示。“但是了解发光、发热以及材料相互作用的方式的这些基本属性”以及光的能量得到更有效地利用的方式“对于各种各样的事情都是非常重要的”。

他补充称，“控制热排放的能力是非常重要的。这是这项工作的真实贡献。”至少到底哪些实际应用最有可能利用这个新的基础技术，他表示，“还言之尚早。”

资料来源：麻省理工学院

Organic & Polymer（有机高分子材料）Weaving a new story for COFS and MOFs

COF-505 is the first 3-D covalent organic framework to be made by weaving together helical organic threads, a fabrication technique that yields significant advantages in structural flexibility, resiliency and reversibility over previous COFs. Credit: Courtesy of Omar Yaghi, Berkeley Lab and UC Berkeley

There are many different ways to make nanomaterials but weaving, the oldest and most enduring method of making fabrics, has not been one of them - until now. An international collaboration led by scientists at the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley, has woven the first three-dimensional covalent organic frameworks (COFs) from helical organic threads. The woven COFs display significant advantages in structural flexibility, resiliency and reversibility over previous COFs - materials that are highly prized for their potential to capture and store carbon dioxide then convert it into valuable chemical products.

"We have taken the art of weaving into the atomic and molecular level, giving us a powerful new way of manipulating matter with incredible precision in order to achieve unique and valuable mechanical properties," says Omar Yaghi, a chemist who holds joint appointments with Berkeley Lab's Materials Sciences Division and

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UC Berkeley's Chemistry Department, and is the co-director of the Kavli Energy NanoScience Institute (Kavli-ENSI).

"Weaving in chemistry has been long sought after and is unknown in biology," Yaghi says. "However, we have found a way of weaving organic threads that enables us to design and make complex two- and three-dimensional organic extended structures."

Yaghi is the corresponding author of a paper in Science reporting this new technique. The paper is titled "Weaving of organic threads into a crystalline covalent organic framework." The lead authors are Yuzhong Liu, Yanhang Ma and Yingbo Zhao. Other co-authors are Xixi Sun, Felipe Gándara, Hiroyasu Furukawa, Zheng Liu, Hanyu Zhu, Chenhui Zhu, Kazutomo Suenaga, Peter Oleynikov, Ahmad Alshammari, Xiang Zhang and Osamu Terasaki.

COFs and their cousin materials, metal organic frameworks (MOFs), are porous three-dimensional crystals with extraordinarily large internal surface areas that can absorb and store enormous quantities of targeted molecules. Invented by Yaghi, COFs and MOFs consist of molecules (organics for COFs and metal-organics for MOFs) that are stitched into large and extended netlike frameworks whose structures are held together by strong chemical bonds. Such frameworks show great promise for, among other applications, carbon sequestration.

Through another technique developed by Yaghi, called "reticular chemistry," these frameworks can also be embedded with catalysts to carry out desired functions: for example, reducing carbon dioxide into carbon monoxide, which serves as a primary building block for a wide range of chemical products including fuels, pharmaceuticals and plastics.

In this latest study, Yaghi and his collaborators used a copper(I) complex as a template for bringing threads of the organic compound "phenanthroline" into a woven pattern to produce an immine-based framework they dubbed COF-505. Through X-ray and electron diffraction characterizations, the researchers discovered that the copper(I) ions can be reversibly removed or restored to COF-505 without changing its woven structure. Demetalation of the COF resulted in a tenfold increase in its elasticity and remetalation restored the COF to its original stiffness.

"That our system can switch between two states of elasticity reversibly by a simple operation, the first such demonstration in an extended chemical structure, means that cycling between these states can be done repeatedly without degrading or altering the structure," Yaghi says. "Based on these results, it is easy to imagine the creation of molecular cloths that combine unusual resiliency, strength, flexibility and chemical variability in one material."

Yaghi says that MOFs can also be woven as can all structures based on netlike frameworks. In addition, these woven structures can also be made as nanoparticles or polymers, which means they can be fabricated into thin films and electronic devices.

"Our weaving technique allows long threads of covalently linked molecules to cross at regular intervals," Yaghi says. "These crossings serve as points of registry, so that the threads have many degrees of freedom to move away from and back to such points without collapsing the overall structure, a boon to making materials with exceptional mechanical properties and dynamics."

Source: Lawrence Berkeley National Laboratory

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为COF和MOF编织一个新的故事

COF-505是第一个由编织螺旋有机线程而制造出的 3-D共价有机框架，编织螺旋有机线程是一项制造技术，其能够在结构灵活性、弹性以及可逆性方面产生明显优于之前的 COF的特点。图片：承蒙伯克利实验室和加州大学伯克利分校的奥马尔•亚吉。

有许多不同的制造纳米材料的方法，但是，编织这种最古老以及最长久的制造织物的方法一直都不是其中之一——直到现在。一个由美国能源署（DOE）的劳伦斯伯克利国家实验室（伯克利实验室）以及加州大学（UC）伯克利分校的科学家进行的国际协作的成果已经通过螺旋有机线程编织了第一个三维共价有机框架（COF）。编织的 COF较之前的 COF在结构灵活性、弹性以及可逆性方面展示出显著的优势——COF是一种材料，由于其能够捕获和储存二氧化碳，然后将其转换成有价值的化工产品原料而受到高度珍视。

“我们已经在原子和分子水平上利用了编织的艺术，这为我们提供了一种强大的新方式，通过难以置信的精确度来操纵物质，从而实现独特的、有价值的机械性能，”联合任命为伯克利实验室材料科学部及加州大学伯克利分校化学系的一位化学家兼科维理能够纳米科学研究所（科维理 -ENSI）的联席主管的奥马尔•亚吉表示。

“在化学中的编织长久以来都是追求的事物，并且其在生物学中是一个未知事物，”亚吉称。“但是，我们已经一种编织有机线程的方法，其能够令我们设计以及制造出复杂的二维及三维有机扩展结构。”

亚吉是《科学》杂志报告这一新技术的一篇论文的通讯作者。论文的题目是“将有机线程编织成结晶共价有机框架”。主要作者有刘于中、马燕航以及赵英博。其他合著者包括孙西西、费利佩•甘达拉、裕康古河、刘政、朱寒雨、朱晨晖、末永一友、彼得•奥列尼科夫、艾哈迈德•奥尔沙姆默瑞、张翔以及修寺崎。

COF和它的对等材料——金属有机框架（MOF）——是具有能够吸收和储存大量靶向分子的巨大内表面积的多孔三维晶体。通过亚吉地发明，COF和MOF是由被缝合到其结构通过强大的化学键结合在一起的大型扩展网状框架中的分子（COF的有机物和MOF的金属有机物）组成的。这样的框架除了其他的应用外还显示出了极大地碳汇希望。

通过亚吉开发的另一项技术，称为“网状化学”，这些框架也能够嵌入催化剂以实现期望的功能：例如，将二氧化碳还原为一氧化碳，其用作广泛的化学产品的主要构成，例如燃料、药品和塑料。

在这个最新的研究中，亚吉和他的合作者利用一种铜（ I）的化合物作为模板，将有机化合物“菲咯”的线程变成一种纺织图案，从而产生他们所谓的 COF-505免疫基框架。通过X射线和电子衍射表征，研究人员发现，铜（I）离子能够逆向删除或恢复成 COF-505，并且不会改变其纺织结构。COF的脱金属化导致其弹性增加了十倍，并且再金属化将 COF恢复到原来的刚度。

“我们的系统能够通过简单的操作可逆性地在这两种弹性状态中进行切换，扩展化学结构中首类这种示范，这意味着这些状态之间的循环能够在不降低或改变结构的情况下反复进行，”亚吉表示。“根据这些结果，我们很够轻易地想象出结合异常弹性、强度、柔韧性及化学变性在一种材料中的分子布的创造。”

亚吉表示，MOF也能够像所有基于网状框架的结构一样得到编织。此外，这些编织结构也能够像纳31


米颗粒或聚合物一样进行制造，这意味着它们能够被制造成为薄膜及电子设备。“我们的编织技术令共价分子的长线程定期交叉，”亚吉说。“这些交叉点作为登记点，从而线程拥

有许多的自由度来回向该点移动而不会破坏整体结构，能够生产出具有卓越的机械性能和动态的材料。”资料来源：劳伦斯伯克利国家实验室

Color-changing indicators highlight microscopic damage

When cracks form,microbeads embedded in the material break open and cause a chemical reaction that highlights the damaged area.Credit:Image courtesy Nancy Sottos

Damage developing in a material can be difficult to see until something breaks or fails.A new polymer damage indication system automatically highlights areas that are cracked,scratched or stressed,allowing engineers to address problem areas before they become more problematic.

The early warning system would be particularly useful in applications like petroleum pipelines,air and space transport,and automobiles-applications where one part's failure could have costly ramifications that are difficult to repair.Led by U.of I.materials science and engineering professor Nancy Sottos and aerospace engineering professor Scott White,the researchers published their work in the journal Advanced Materials.

"Polymers are susceptible to damage in the form of small cracks that are often difficult to detect.Even at small scales,crack damage can significantly compromise the integrity and functionality of polymer materials,"Sottos said."We developed a very simple but elegant material to autonomously indicate mechanical damage."

The researchers embedded tiny microcapsules of a pH-sensitive dye in an epoxy resin.If the polymer forms cracks or suffers a scratch,stress or fracture,the capsules break open.The dye reacts with the epoxy,causing a dramatic color change from light yellow to a bright red-no additional chemicals or activators required.

The deeper the scratch or crack,the more microcapsules are broken,and the more intense the color.This helps to assess the extent of the damage.Even so,tiny microscopic cracks of only 10 micrometers are enough to cause a color change,letting the user know that the material has lost some of its structural integrity.

""Detecting damage before significant corrosion or other problems can occur provides increased safety and reliability for coated structures and composites,"White said.White and Sottos are affiliated with the Beckman Institute for Advanced Science and Technology at the U.of I.

The researchers demonstrated that the damage indication system worked well for a variety of polymer materials that can be applied to coat different substrates including metals,polymers and glasses.They also found that the

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system has long-term stability-no microcapsule leaking to produce false positives,and no color fading.

In addition to averting unforeseen and costly failure,another economic advantage of the microcapsule system is the low cost,Sottos said.

"A polymer needs only to be 5 percent microcapsules to exhibit excellent damage indication ability,"Sottos said."It is cost effective to acquire this self-reporting ability."

Now,the researchers are exploring further applications for the indicator system,such as applying it to fiber-reinforced composites,as well as integrating it with the group's previous work in self-healing systems.

"We envision this self-reporting ability can be seamlessly combined with other functions such as self-healing and corrosion protection to both report and repair damage,"Sottos said."Work is in progress to combine the ability to detect new damage with self-healing functionality and a secondary indication that reveals that crack healing has occurred."

Source:Univ.of Illinois at Urbana-Champaign

变色指示器突显微观损伤

当裂缝形成时 ,微嵌在材料中的微珠就会破开并引起化学反应 ,突显了受损区域。注 :图片由 Nancy Sottos友情提供。

直到发生断裂或失效前，材料中的损伤发展很难发现。新的聚合物损伤指示系统会自动突出显示破裂、划伤或受压区域,使得工程师在更多问题出现前指出问题区域。

早期预警系统在如石油管道、航空航天运输和汽车应用中尤其具有使用价值，这些应用中一个部件的故障可能会产生难以处理的高昂代价的后果。在美国伊利诺伊大学材料科学与工程学教授 Nancy Sottos和航空航天工程学教授 Scott White带领下，研究者们在《先进材料》杂志上发表了他们的成果。

Sottos说：“聚合物以很难发现的小裂缝形式易受损坏。即使程度较小,裂纹损伤可能极大危害高分子材料的完整性和功能,我们开发了一种非常简单但是精致的材料来自动显示机械损伤。”

研究者在环氧树脂嵌入 pH敏感性染料微胶囊。如果聚合物形成裂缝或遭到刮碰,受压或断裂,胶囊会破开。染料与环氧树脂反应,导致显著的颜色变化,从淡黄色到一个明亮的红色,不需要额外的化学物质或催化剂。

划痕或裂纹越深,微胶囊破裂的越多,颜色就越深。这有助于评估损伤的程度。即便如此, 只有 10微米细微的裂缝足以引起颜色的变化,让使用者知道材料已经失去了它的一些结构完整性。

White说：“在严重的腐蚀或其他问题出现之前检测损伤，提高了对涂层结构和复合材料的安全性和可靠性。” White 和 Sottos是隶属于伊利诺伊大学先进的科学和技术方面的贝克曼研究所，。33


研究人员证实损伤指示系统对各种高分子材料有良好的效果,可应用于喷涂包括金属、聚合物和玻璃的不同基质。他们还发现,系统长期稳定-没有微胶囊泄漏产生误报,也没有褪色。

Sottos说，除了避免不可预见的和高成本的故障, 微胶囊系统另一个经济优点是低成本。Sottos 说：“聚合物只需要 5%微胶囊来展现极好的损伤指示能力 ,获取这种自报告能力的成本有效

的。”现在,研究人员正在探索指示系统的更多用途,如应用到纤维增强复合材料,以及将其与团队先前的自愈

合系统工作进行融合。Sottos 说：“我们设想这种自我报告的能力，能够与例如自愈和防腐的其他功能完美结合来报告和修

复损伤,与自修复功能结合检测新的损伤和显示裂纹愈合已出现的二次指示的工作正在进行中。”来源:伊利诺伊大学香槟分校

E-Material（电子材料）Switchable Material Could Enable New Memory Chips

This diagram shows how an electrical voltage can be used to modify the oxygen concentration, and therefore the phase and structure, of strontium cobaltites. Pumping oxygen in and out transforms the material from the brownmillerite form (left) to the perovskite form (right). Photo: MIT

Two MIT researchers have developed a thin-film material whose phase and electrical properties can be switched between metallic and semiconducting simply by applying a small voltage. The material then stays in its new configuration until switched back by another voltage. The discovery could pave the way for a new kind of “nonvolatile” computer memory chip that retains information when the power is switched off, and for energy conversion and catalytic applications.

The findings, reported in the journal Nano Letters in a paper by MIT materials science graduate student Qiyang Lu and associate professor Bilge Yildiz, involve a thin-film material called a strontium cobaltite, or SrCoOx.

Usually, Yildiz says, the structural phase of a material is controlled by its composition, temperature, and pressure. “Here for the first time,” she says, “we demonstrate that electrical bias can induce a phase transition in the material. And in fact we achieved this by changing the oxygen content in SrCoOx.”

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“It has two different structures that depend on how many oxygen atoms per unit cell it contains, and these two structures have quite different properties,” Lu explains.

One of these configurations of the molecular structure is called perovskite, and the other is called brownmillerite. When more oxygen is present, it forms the tightly-enclosed, cage-like crystal structure of perovskite, whereas a lower concentration of oxygen produces the more open structure of brownmillerite.

The two forms have very different chemical, electrical, magnetic, and physical properties, and Lu and Yildiz found that the material can be flipped between the two forms with the application of a very tiny amount of voltage — just 30 millivolts (0.03 volts). And, once changed, the new configuration remains stable until it is flipped back by a second application of voltage.

Strontium cobaltites are just one example of a class of materials known as transition metal oxides, which is considered promising for a variety of applications including electrodes in fuel cells, membranes that allow oxygen to pass through for gas separation, and electronic devices such as memristors — a form of nonvolatile, ultrafast, and energy-efficient memory device. The ability to trigger such a phase change through the use of just a tiny voltage could open up many uses for these materials, the researchers say.

Previous work with strontium cobaltites relied on changes in the oxygen concentration in the surrounding gas atmosphere to control which of the two forms the material would take, but that is inherently a much slower and more difficult process to control, Lu says. “So our idea was, don’t change the atmosphere, just apply a voltage.”

“Voltage modifies the effective oxygen pressure that the material faces,” Yildiz adds. To make that possible, the researchers deposited a very thin film of the material (the brownmillerite phase) onto a substrate, for which they used yttrium-stabilized zirconia.

In that setup, applying a voltage drives oxygen atoms into the material. Applying the opposite voltage has the reverse effect. To observe and demonstrate that the material did indeed go through this phase transition when the voltage was applied, the team used a technique called in-situ X-ray diffraction at MIT’s Center for Materials Science and Engineering.

The basic principle of switching this material between the two phases by altering the gas pressure and temperature in the environment was developed within the last year by scientists at Oak Ridge National Laboratory. “While interesting, this is not a practical means for controlling device properties in use,” says Yildiz. With their current work, the MIT researchers have enabled the control of the phase and electrical properties of this class of materials in a practical way, by applying an electrical charge.

In addition to memory devices, the material could ultimately find applications in fuel cells and electrodes for lithium ion batteries, Lu says.

“Our work has fundamental contributions by introducing electrical bias as a way to control the phase of an active material, and by laying the basic scientific groundwork for such novel energy and information processing devices,” Yildiz adds.

In ongoing research, the team is working to better understand the electronic properties of the material in its different structures, and to extend this approach to other oxides of interest for memory and energy applications, in collaboration with MIT professor Harry Tuller.

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José Santiso, the nanomaterials growth division leader at the Catalan Institute of Nanoscience and Nanotechnology in Barcelona, Spain, who was not involved in this research, calls it “a very significant contribution” to the study of this interesting class of materials, and says “it paves the way for the application of these materials both in solid state electrochemical devices for the efficient conversion of energy or oxygen storage, as well as in possible applications in a new kind of memory devices.”

The work was supported by the National Science Foundation.

可转换的材料可能会产生新的内存芯片

此图显示了一个电压是如何能够被用来改变氧浓度的，并且因此用于改变锶辉钴矿的相位和结构。抽送氧气将该材料从钙铁石的形式（左）转换为钙铁矿的形式（右）。图片：MIT

两个MIT的研究人员已经开发出一种薄膜材料，其相位及电性能能够通过施加简单的一个小电压令其在金属和半导体之间进行转换。然后该材料会维持在新的配置上，直到有另一个电压将其切换回来。这一发现能够为新的“非易失性的”能够在电源关闭时保留信息的电脑记忆芯片、以及能量转换和催化应用铺平道路。

这项由MIT材料科学系的研究生鲁祁阳及副教授比尔格•伊尔迪斯发表于《纳米快报》杂志的论文的研究结果涉及了一个称为锶辉钴矿或 SCoOx的薄膜材料。

通常，伊尔迪斯称，一个材料的结构相是由它的组成、温度和压力来控制的。“这是首次，”她称，“我们证明了电压偏差能够诱导材料的相变。而事实上，我们是通过改变 SrCoOx中的氧气含量来实现这一点。”

“两种不同的结构依赖于其每个单位细胞包含多少的氧原子，并且这两种结构具有相当不同的属性，”鲁解释称。

该分子结构中的这些配置的一个称这为钙钛矿，并且另一种是所谓的钙铁石。当更多的氧气存在时，其形成了钙钛矿紧密封闭的笼状晶体结构，而氧的较低浓度会产生钙铁石更开放的结构。

这两种形式具有非常不同的化学、电、磁和物理性质，并且鲁和伊尔迪斯发现，该材料能够通过一个非常小量的电压——只有 30毫伏（0.03伏）——的应用在这两种形式之间相互转换。而且，一旦改变，新的配置会保持稳定，直到其通过第二次电压的应用而转换回之前的配置。

锶辉钴矿只是一类称为过渡金属氧化物的材料中的一个，其被认为是有望应用于各种应用，包括燃料电池中的电极、允许氧气通过用于气体分离的膜，以及电子装置，例如忆阻器——一种非易失性的、超快的高能效存储装置的形式。研究人员表示，通过使用一个很小的电压来触发这样一个相变能够为这些材料开辟许多用途。

之前有关锶辉钴矿的工作依赖于改变周围气体氛围中的氧浓度来控制该材料将拥有这两种形式中的36


哪种，但是其在本质上要慢得多，并且对于控制来说是一个更困难的过程，鲁表示。“因此我们的想法是，不改变气氛，仅仅是施加电压。”

“电压改变了该材料所面临的有效的氧分压，”伊尔迪斯补充称。为了使之成为可能，研究者在一个衬底上沉积了该材料（钙铁石相）的一个非常薄的膜，为此他们使用了氧化钇稳定的氧化锆。

在该设置中，施加一个电压来驱动氧原子进入该材料。施加相反的电压具有相反的效果。为了观察和证明该材料确实在施加电压时经历了这一相变，该小组在 MIT材料科学与工程中心的一项称为原位 X射线衍射的技术。

改变环境中的气体压力和温度令该材料在这两种相之间相互转换的基本原理是在去年由美国橡树岭国家实验室的科学家们开发出来的。“虽然有趣，这对于控制所使用的装置的性能并不是一个实用的方法，”伊尔迪斯表示。通过他们目前的研究，MIT的研究人员令这类材料的相和电性能的控制成为了一种实际的方式，通过施加电荷。

除了存储设备，该材料可能最终会应用于燃料电池和锂离子电池的电极，鲁表示。“我们的工作拥有基本内容，通过引入电偏压作为一种控制一个活性材料的相的方式，并且通过为这

种新颖的能量和信息处理装置铺设基本的科学基础，”伊尔迪斯补充称。在正在进行的研究中，该小组与MIT的教授哈里•土勒进行合作，努力更好地了解该材料在不同材

料下的电子特性，并且将该方法延伸至其他用于内存及能源应用的氧化物。没有参加这项研究的西班牙巴塞罗那加泰罗尼亚纳米科学和纳米技术研究所纳米材料生长分裂的领

导者何塞•桑蒂索称其对于这类有趣的材料的研究来说是“一个非常显著的贡献”，并称“它为这些材料在用于能量高效转换或储氧的固态电化学装置的应用方面以及新型存储装置的可能应用方面铺平了道路。”

这项工作受到了美国国家科学基金会的支持。

Watching electrons cool in 30 quadrillionths of a second

An illustration showing single layers of graphene with thin layers of insulating boron nitride that form a sandwich structure. Credit: Qiong Ma

Two University of California, Riverside assistant professors of physics are among a team of researchers that have developed a new way of seeing electrons cool off in an extremely short time period.

The development could have applications in numerous places where heat management is important, including visual displays, next-generation solar cells and photodetectors for optical communications.

In visual displays, such as those used in cell phones and computer monitors, and photodetectors, which have a

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wide variety of applications including solar energy harvesting and fiber optic telecommunications, much of the energy of the electrons is wasted by heating the material. Controlling the flow of heat in the electrons, rather than wasting this energy by heating the material, could potentially increase the efficiency of such devices by converting excess energy into useful power.

The research is outlined in a paper, "Tuning ultrafast electron thermalization pathways in a van der Waals heterostructure," published online Monday (Jan. 18) in the journal Nature Physics. Nathan Gabor and Joshua C.H. Lui, assistant professors of physics at UC Riverside, are among the co-authors.

In electronic materials, such as those used in semiconductors, electrons can be rapidly heated by pulses of light. The time it takes for electrons to cool each other off is extremely short, typically less than 1 trillionth of a second.

To understand this behavior, researchers use highly specialized tools that utilize ultra-fast laser techniques. In the two-dimensional material graphene cooling excited electrons occurs even faster, taking only 30 quadrillionths of a second. Previous studies struggled to capture this remarkably fast behavior.

To solve that, the researchers used a completely different approach. They combined single layers of graphene with thin layers of insulating boron nitride to form a sandwich structure, known as a van der Waals heterostructure, which gives electrons two paths to choose from when cooling begins. Either the electrons stay in graphene and cool by bouncing off one another, or they get sucked out of graphene and move through the surrounding layer.

By tuning standard experimental knobs, such as voltage and optical pulse energy, the researchers found they can precisely control where the electrons travel and how long they take to cool off. The work provides new ways of seeing electrons cool off at extremely short time scales, and demonstrates novel devices for nanoscale optoelectronics.

This structure is one of the first in a new class of devices that are synthesized by mechanically stacking atomically thin membranes. By carefully choosing the materials that make up the device, the researchers developed a new type of optoelectronic photodetector that is only 10 nanometers thick. Such devices address the technological drive for ultra-dense, low-power, and ultra-efficient devices for integrated circuits.

The research follows advances made in 2011 Science article, in which the research team discovered the fundamental importance of hot electrons in the optoelectronic response of devices based on graphene.

Source: University of California – Riverside

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在30千万亿分之一秒的时间内看着电子冷却

一个显示出具有形成一个夹层结构的薄层绝缘氮化硼的单层石墨的示意图。图片：马琼两位美国加州大学滨江分校的物理系副教授参加了一个研究小组，该小组已经开发出一种在极短时

间内见证电子冷却下来的新方式。该发展可能在许多地方都具有应用，其中热管理最为重要，包括视觉显示器、下一代太阳能电池以及

用于光通信的光电检测器。在可视显示器中，例如手术和电脑显示器中的那些，以及在太阳能收集和光纤通信方面拥有广泛应

用的光电检测器中的那些，大多数的电子能量因加热该材料而被浪费了。控制电子内的热流，而不是通过加热该材料来浪费这种能量，可能会潜在地通过将额外的能量转换成有用的功率而增加这种装置的效率。

这项研究在一篇名为“在范德华异质中调整超快电子热化途径”的论文中提及，该论文于周一（ 1月18日）在线发表于《自然物理》杂志。加州大学河滨分校的物理学副教授内森•伽柏和乔舒亚 C.H.刘是其中的合著者。

在电子材料中，例如那些用于半导体的材料，电子能够通过光脉冲得到迅速加热。电子彼此冷却所花费的时间非常短暂，通常不到一万亿分之一秒。

为了理解这种行为，研究人员使用了高度专业化的利用超快激光技术的工具。二维材料石墨冷却激发的电子发生得更快，仅使用 30千万亿分之一秒。以往的研究在努力捕获这个非常快的行为。

为了解决这个问题，研究人员使用了一种完全不同的方法。他们结合单层石墨烯和薄层绝缘氮化硼以形成夹层结构，即所谓的范德华异质结构，从而为电子提供了两条路径以选择何时开始冷却。无论电子是停留在石墨烯内并且通过反弹彼此来进行冷却，还是它们被吸出石墨烯并且在周围的层内移动。

通过调整标准实验旋钮，例如电压和光脉冲能量，研究人员发现，他们能够精确地控制电子穿行的地点以及他们冷却的时间。这项工作为在极短的时间内见证电子冷却提供了新的方式，并且为纳米光电子展示了新型设备。

该结构是第一个由机械堆叠的原子型薄膜合成的新一类设备中的结构。通过仔细地选择构成该装置的材料，研究人员研制出一种新型的仅有 10纳米厚的光电探测器。这样的设备强调了集成电路中所使用的超密集、低功耗的超高效设备的技术性驱动力。

这项研究遵循了 2011科学文献中取得的进展，在该文献中，研究人员在基于石墨烯的器件的光电响应中发现了热电子的根本重要性。

资料来源：加州大学—河滨分校

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Electrons and liquid helium advance understanding of zero-resistance

This is a cell (container) where the electrons on liquid helium experiments are conducted. Credit: OIST

The end of Moore's Law -- the prediction that transistor density would double every two years -- was one of the hottest topics in electronics-related discussions in 2015. Silicon-based technologies have nearly reached the physical limits of the number and size of transistors that can be crammed into one chip, but alternative technologies are still far from mass implementation. The amount of heat generated during operation and the sizes of atoms and molecules in materials used in transistor manufacturing are some of problems that need to be solved for Moore's Law to make a comeback.

Atomic and molecular sizes cannot be changed, but the heat problem is not unsolvable. Recent research has shown that in two-dimensional systems, including semiconductors, electrical resistance decreases and can reach almost zero when they are subjected to magnetic and microwave influence. Electrical resistance produces a loss of energy in the form of heat; therefore, a decrease in resistance reduces heat generation. There are several different models and explanations for the zero-resistance phenomenon in these systems. however, the scientific community has not reached an agreement on this matter because semiconductors used in electronics are complex and processes in them are difficult to model mathematically.

Research conducted by the Quantum Dynamics Unit at Okinawa Institute of Science and Technology graduate University (OIST) could represent an important step in understanding two-dimensional semiconductors. The Unit's latest paper, published in Physical Review Letters, describes anomalies in the behavior of electrons in electrons on liquid helium two-dimensional system.

The system is maintained at a temperature close to absolute zero (-272.75ºC or 0.4K) to keep the helium liquefied. Extraneous electrons are bound to the helium surface because their presence causes slight changes in the orbits of helium electrons, inducing a subtle positive charge at the helium surface. At the same time, free electrons lack the energy required to penetrate the surface to enter the liquid. The resulting system is ideal for studying various electron properties, as it has virtually zero impurities, which avoids artefacts caused by defects of surface and structure, or due to the presence of other chemical elements. Prof. Denis Konstantinov, head of the Quantum Dynamics Unit, and his team study conditions under which electrons can violate selection rules regulating transitions from one state to another.

In a macro-world we perceive transitions from one state to another as happening gradually. For example, a person traveling from town A to town B can make an infinite number of stops. In micro-world that is not always the case.

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Properties, such as energy, position, speed, and color, can be quantised, i.e. they can occur only in discrete quantities. In other words, the traveler can be either in town A, or town B, but not somewhere in-between.

Since electron energy is quantised, electrons can occupy only specific energy levels. Quantum theory predicts that in a two-dimensional electron system, where moving electrons are confined to one plane, under a strong magnetic field electrons also will be restricted to climbing only one step of the energy level ladder at a time. however, the experiments show that electrons can jump to higher energy levels, skipping levels between. Prof. Konstantinov and his team are very excited about this discovery: "It is not everyday that we get a chance to observe the violation of quantum theory predictions!"

In order to study abnormalities in electron state changes, the scientists applied a strong vertical magnetic field and then bombarded the system with microwave photons. Under these conditions selection rules seem to stop working. Prof. Konstantinov says that his group had theorized that such a phenomenon is possible and now they have proven it.

Selection rules describe a theoretical, absolutely pure, and homogenous system with no disorders. Real-life systems are more complex. In the case of electrons on helium, the system is pure and homogenous, but the surface of liquid helium is nonetheless disturbed by capillary waves -- ripples associated with the surface tension and similar to small, circular ripples in a pond when a pebble is tossed into the water. The height of these ripples is only the diameter of a hydrogen atom, but in combination with microwave radiation they create enough deviation from an ideal system for selection rules to change.

Conditions modeled in the Quantum Dynamics Unit's experiment are similar to those that led to observations of zero resistance in semiconductors. however, the electrons on helium system is relatively simple and can be described mathematically with great precision. Studying this system will further the development of quantum physics and will contribute to our understanding of electrons and various electrical phenomena. moreover, with some adjustments models, based on electrons on helium systems can be adapted to more complex systems, such as two-dimensional semiconductors.

Source: Okinawa Institute of Science and Technology Graduate Univ.

电子和液氮推进了对零电阻的理解

这是一个进行液氮中的电子实验的细胞（容器）。资料来源：冲绳科技学院（OIST）摩尔定律的终结：晶体管密度每两年就会加倍的预测是在 2015年电子学有关的讨论中最热门的话题。

以硅为基础的技术最近已经达到可以被勉强塞入一个单晶片的数量和晶体管体积的限制，但是供选择的41


技术仍然离大量实行十分遥远。操作期间的热量产生和材料中的使用在晶体管制造中的原子和分子的大小都是问题，这些问题都是摩尔定律想要东山再起需要解决的。

原子和分子大小不能被改变，但是热度问题并不是不能被解决的。最近的研究显示在二维体系中，包括半导体和电阻减少，并且在经过地磁和微波影响后会达到接近零的状态。电阻造成了以热的形式的能量损失。因此，阻力方面的减少降低了热生成量。在这个体系中，有几个对零电阻现象不同的模式和解释。但是科学团体并没有对这个问题达成一致意见，因为使用在电子钟的半导体是复杂的，而且它们中的进程是很难通过数学计算来模拟的。

由冲绳理工学院的量子动力学机构进行的研究代表着在二维半导体理解方面的重要一步。这个机构最新的论文出版在《物理评论快报》上，记述了在液氦二维系统中电子性能的异常现象。

这个系统包含在一个一个接近零的温度中（(-272.75ºC 或者 0.4K)来使氦液化。外来电子一定要到氦的表面因为它们的存在造成了氦电子轨道的轻微改变，包括在氦表面的一个微妙的正电荷。同时，自由电子缺乏要求刺入表面进入液体的能量。这种作为结果的系统对于研究各种电子特性是非常理想的，因为它有事实上的零杂质可以避免由表面和结构的瑕疵造成的人工制品，这或者也是由于其它的化学成分的存在。量子力学机构的 Denis Konstantinov,教授和他的团队研究在电子可以违反调整一个状态到另一个状态的选择规则下的状况。

在一个大世界我们在某现象逐渐发生时能感觉到从一个状态到另一个状态的过渡。例如，一个从城镇A旅行到城镇 B的人中间可能会有无数个停止。在微观世界不总是这种情况。如能量、方位、速度和颜之类的特性可以被量子化，也就是说，它们只能发生在离散的数量中。换句话说，旅行者可以在城镇A或者城镇 B，但不可能在两者之间的地方。

尽管电子能量是可以量化的，电子只能占据比能水平。量子理论预示在二维电子体系中，移动的电子被约束在一个地方，处于强电磁场也会被限制只能一次爬上一个能量水平梯度的台阶。然而，试验证明电子可以跳到更高的能量水平，跃入中间的水平。Konstantinov和他的团队对于这个发现是非常兴奋的：“不是每天都能得到机会观察到违反量子理论预测的现象！”

为了研究电子态改变的异常现象，科学家们应用了一种强垂直磁场，然后用微波光子轰炸了这个体系。在这些状况之下，选择规则看起来停止工作了。Konstantinov教授说他的小组已经对这种现象是可能的形成了理论，现在他们已经证明了它。

选择规则描述了一种理论化的、纯粹的、均一和有序的体系。现实系统更加复杂。至于在氦中的电子，这个系统是纯粹的和均一的，但是液氦的表面却会受到毛细波的干扰，这种微波和表面张力有关，这和当用卵石向湖中投入时池塘中的小圆涟漪很相似。这种涟漪的高度仅是氢原子的直径，但是和微波辐射相结合，他们创造了足够的为了选择规则的改变而从理想体系中的分离。

在量子动力学机构的试验中模拟的状况和半导体零阻力的观察很相似。然而，氦体系中的电子是相当简单的，可以极精确地经过数学计算得以描述。研究这个体系将会加深量子物理的发展，将有助于我们对于电子和各种电子现象的理解。更有之，利用一些基于氦体系电子的调整模型，可以适用于如二维半导体之类的更复杂的体系。

资料来源：冲绳科学和技术研究所

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