Blog Archive

Saturday, February 24, 2007

周文重被任命为中国驻美国大使

外交部发言人刘建超24日在例行记者会上说,周文重已经被任命为中国驻美国大使,不久将去美国赴任。此前,国务院已任命前驻美大使杨洁篪为外交部副部长,免去周文重的外交部副部长职务。

周文重,江苏省人,大学毕业。1970年至1973年任中华人民共和 国北京外交人员服务局科员。1973年至1975年在大不列颠及北爱尔兰联合王国巴斯大学、伦敦经济学院进修。1975年至1978年任外交部翻译室科 员。1978年至1983年任驻美利坚合众国大使馆随员、三秘。1983年至1987年任外交部翻译室二秘、副处长、处长。1987至1990年任驻旧金 山总领馆副总领事。1990年至1993年任驻巴巴多斯特命全权大使兼驻安提瓜和巴布达特命全权大使。1993年至1994年任外交部美大司副司长。1994年至1995年任驻洛杉矶总领事(大使衔)。1995年至1998年任驻美利坚合众国大使馆公使。1998年至2001年任驻澳大利亚联邦特命全 权大使。2001年至2003年任外交部长助理。2003年5月被任命为外交部副部长

Friday, February 23, 2007

由"王丹:我为什么希望到香港教书"想到的

很小的时候,在电视上看到89天安门事件,后来学校的礼堂里贴了很多在这次事件中牺牲的解放军战士,再后来高三上政治课时, 听一个思想偏激的老师提过89学潮,直到再上次一个朋友提到,已经18年了。虽然自己没有赶上那个年代,没有亲身体验经历过,说法很多:89事件当事人,香港媒体,台湾媒体,海外媒体,和我们官方媒体,但是再过一百年,我也同意

“ 上个世纪80年代末、90年代初,在中国发生了一场严重的政治风波,苏联解体,东欧剧变,在这个关系党和国家命运的严重的时刻,党中央紧紧依靠全党同志和全国人民,坚持十一届三中全会以来的路线不动摇,成功地稳住了中国改革开放的大局,捍卫了中国特色的社会主义事业。”

仔细看看,20个六四事件的录像和赵紫阳的讲话,我真的想问你们:王丹、封从德、柴玲、吾尔开希,你们到底想怎么样?你们都干了什么?18年过去了,你们还是没有恢复理智?你们有什么资格对政府说三道四? 柴玲,这个女人,曾经在录像[1]里面说:“中国,你这样一个国家,太令我伤心了,虽然我们不能骂自己的祖国,但是我真的不愿为你奋斗” ,这个女人,过现在波士顿经验IT企业,曾经还夸口“希望能挣足够多的钱,买下中国,再把她建设成一个富强,民主的共和国”!

白痴女人,我想告诉你:你滚远点,祖国没有你,是万幸的!


Reference:

[1]天安门六四事件录像

[2]赵紫阳於凌晨4時50分前往天安门广场的谈话:

同学们,我们来得太晚了。对不起同学们了。你们说我们、批评我们,都是应该的。我这次来不是请你们原谅。我想说的是,现在同学们身体已经非常虚弱, 绝食已经到了第七天,不能再这样下去了。绝食时间长了,对身体会造成难以弥补的损害,这是有生命危险的。现在最重要的是,希望尽快结束这次绝食。我知道, 你们绝食是希望党和政府对你们所提出的问题给以最满意的答复。我觉得,我们的对话渠道是畅通的,有些问题需要一个过程才能解决。比如你们提到的性质、责任 问题,我觉得这些问题终究可以得到解决,终究可以取得一致的看法。但是,你们也应该知道,情况是很复杂的,需要有一个过程。你们不能在绝食已进入第七天的 情况下,还坚持一定要得到满意答复才停止绝食。

你们还年轻,来日方长,你们应该健康地活着,看到我们中国实现四化的那一天。你们不像我们,我们已经老了,无所谓了。国家和你们的父母培养你们上大 学不容易呀!现在十几、二十几岁,就这样把生命牺牲掉哇,同学们能不能稍微理智地想一想。现在的情况已经非常严重,你们都知道,党和国家非常着急,整个社 会都忧心如焚。另外,北京是首都,各方面情况一天天严重,这种情况不能再继续下去了,同学们都是好意,为了我们国家好,但是这种情况发展下去,失去控制, 会造成各方面的严重影响。

总之,我就是这么一个心意。如果你们停止绝食,政府不会因此把对话的门关起来,绝不会!你们所提的问题,我们可以继续讨论。慢是慢了一些,但一些问 题的认识正在逐步接近。我今天主要是看望一下同学们,同时说一说我们的心情,希望同学们冷静地想一想这个问题。这件事情在不理智的情况下,是很难想清楚 的。大家都这么一股劲,年轻人么,我们都是从年轻人过来的,我们也游过行,卧过轨,当时根本不想以后怎么样。最后,我再次恳请同学们冷静地想一想今后的 事。有很多事情总是可以解决的。希望你们早些结束绝食,谢谢同学们。

[3]王丹:我为什么希望到香港教书
六四已经过去将近18年了.这18年来,陆续有很多的知识分子和民运 人士被迫离开自己的国家,告别自己的家人,走上流亡的道路.这18年来,可以说,大家没有一天不盼望着可以回去自己的国家,与自己的家人朋友团聚的.我当 然也不例外.尤其是在春节这样的中国的传统节日,当然更希望能够跟家人一起吃团圆饭. 这样的全家团聚在别人的是理所当然的事情,可是在我,已经将近十几年没有过了.

在 将近8年的美国读书生涯之后,今年6月我预计将要毕业,即将面临人生的另一个阶段---就业.作为一个博士生,最主要的就业选择就是教书.如果我可以选 择,我会希望到香港去寻找教职.这首先我本人对香港一直有特殊的感情.这不仅是因为六四的时候,香港人将自己的命运与我们的命运连接在一起,我们当时可以 说是共患难;也是因为18年来,只有香港,坚持每年举办大型六四纪念活动,成为漫漫长夜中的一盏明灯.我一直很希望能够对香港人的热心有所回报.

其 实,希望到香港工作,另外很大的一个原因,也是因为香港离中国大陆很近,在”自由行”之后,家人探视会更加方便.我父母今年都已经是70高龄.尽管他们可 以去美国看望我.但是自古都是黑发人看白发人,哪有白发人看黑发人的道理呢?况且中国到美国路程遥远,对于年长者来说是越来越难以承受的负担.所以他们看 望我的机会会越来越少.我当然希望能够离他们近一些.尤其是我母亲因为心脏病的问题,身体状况并不是很好,作为子女,当然更希望能够在她身边照顾.

我 想只要是人,谁没有父母呢?今天我希望来香港,很大程度上是作为一个子女出于亲情的愿望.我可以理解中共政府,也许包括香港政府对于我的政治立场的反对. 但是中国毕竟有一个讲究基本的人情的文化传统,这种基本的伦理我很想看看当局是不是因为政治立场而放弃.今天,曾经与中共有血海深仇的国民党,它的主席都 可以访问大陆,当年那些杀了无数中共党员的国民党老将军都可以回去探视,我实在不理解,为什么当年要求推动民主的和平示威者,今天已经18年过去了,却无 论如何不允许回到大陆呢?今天,如果中共连一介书生都害怕,他的统治是否真的稳定,恐怕就要打上一个很大的问号了?

Nanotube remote-controlled actuators boost microelectromechanical systems (MEMS) applications

21 February 2007

In a recent article published in Nanotechnology, Shaoxin Lu and Balaji Panchapakesan, Department of Electrical and Computer Engineering, University of Delaware, US, reported on the construction of carbon-nanotube-based micro-optomechanical systems(CNT-MOMS) that could impact MEMS applications. While most MEMS devices use electrical energy to cause actuation, devices based on nanotubes can be powered optically with superior performance and low power compared to their electrostatic MEMS counterparts. The researchers have developed a CMOS-compatible process based on thin carbon nanotube film transfer, patterning and plasma etching, which properly integrates carbon nanotube ensembles in the MEMS devices. A micromechanical gripper has been demonstrated as an example of the concept CNT-MOMS. Displacement of ∼24 μm was obtained from a gripper of 430 μm in length, comparable to that of electrical-driven counterparts, but only at a low optical power cost of ∼240 μW. These CNT-MOMS can be implemented to design smart systems with multiple functionalities while powered remotely by light. It could have applications in adaptive optics, remote manipulation, and robotics for space and sensor applications. Panchapakesan believes that nanotube MOMS could impact future MEMS and nano-applications as they offer out-of-plane actuation, batch fabrication, scalability, remote-controllability, low power requirement and low cost compared to their MEMS electrical counterparts.

Chain Mail Fabric a Perfect Fit

Contemporaries of the ancient Greeks might find something familiar within the walls of the Micro and Nanotechnology Lab at the University of Illinois. In constructing a new type of smart fabric, researchers Jonathan Engel and Chang Liu have used interconnecting rings and links to create a textile looking a bit like the chain mail used by warriors dating back 2,000-plus years.

“It’s somewhat of a crazy idea, I guess,” Liu told PhysOrg.com. “We were interested in using microtechnology to build something that could flex and bend. The chain mail construction is nothing fancy, but it’s an interesting structure that hasn’t been used much recently.”

(chain mail: Flexible armor composed of small overlapping metal rings, loops of chain, or scales. 铠甲:由相互叠加的小金属环、环状链子或金属鳞片构成的可弯曲的盔甲)

As a flexible MEMS (Microelectromechanical Systems) device, the new fabric represents a milestone in the development of smart textiles. A type of smart device, smart textiles will likely be incorporated into wearable computers—shirts that can detect vital signs, locate bullet wounds, or provide an information network for soldiers on a dispersed battleground, according to recent research (Georgia Tech). Generally, most work on smart fabrics involves integrating the electronic elements into conventional fabrics. Engel and Liu’s integrated circuit, however, is the fabric—a continuous, flexible and stretchable metallic cloth with unique electrical and mechanical properties.

One of the interesting physical characteristics of the micro chain mail is its ability to bend along two axes, allowing the fabric to drape over curved surfaces, wrinkle-free. This ability comes from the geometric network of rings connected by links—each piece of about half a millimeter in length—which can slide and rotate against each other. As the links are pulled taut, the researchers found that the fabric’s length could expand by 32%, with its width decreasing by 56%.

左图:Chain mail fabric draped over a one-inch metal ball. 用这种铠甲包裹的一英寸的金属球

“The flexible fabric can conform to curved surfaces, and be used on objects that move,” explained Liu. “Because of the nature of the fabric, electronics can be easily integrated into the technology. In the future, for example, this type of clothing could shield electromagnetic waves for construction workers.”

Regarding the electronic properties, Engel and Liu found that the displacement of the copper fabric caused variations in its electrical conduction properties, which would enable using the fabric as an electrical device. When the links were fully stretched, making solid electrical contact, the researchers observed a decrease in electrical resistance of nearly seven orders of magnitude.

The scientists also investigated the fabric’s mechanical tensile strength, finding a value of less than half that of the ultimate strength of copper. By inspecting how the fabric broke—failure occurred mostly in the rings rather than the links—the researchers predict that a complex loading occurs in the fabric, different from that in normal copper.

To fabricate this first batch, Engel and Liu used a multilayer microelectroplating process, depositing thin layers of aluminum, copper and photoresist on a substrate to form a mold, which was then filled with copper. In the end, the sacrificial mold layers were “washed out” by soaking in chemicals, leaving the links or rings behind.

While this fabrication occurred on a small scale, the researchers suggest that large-scale manufacturing of the fabric is quite realistic for the future. Further, besides using metal materials, other materials may offer advantages for different applications. For example, a silicon chain mail fabric could generate electricity using solar cells, or detect motion or strain. Polymer elastomers could have an advantage in sensing chemicals, strain or pressure.

“This is just one of the first steps in wearable electronics technology,” said Liu. “The long-term interest is to make computer gear blend in to everyday clothing so that it doesn’t feel intrusive. This is a barrier for people for wearing, for example, solar cells or sensors on their clothing, but it can be overcome by a robust fabric that moves with you.”

Citation: Engel, Jonathan, and Liu, Chang. “Creation of a metallic micromachined chain mail fabric.” J. Micromech. Microeng. 17 (2007) 551-556.

Micromanipulator makes its debut (微操作器首次亮相)

Micromanipulator makes its debut
21 February 2007


Researchers in the US have invented a new gripping device that can manipulate micro-sized objects using multiple, coordinated “fingers". The device, which works in a similar way to how humans manipulate centimetre-sized objects, is better than existing micro-tweezers that can only open and close to grasp an object. The design of the "micromanipulator station" could also be improved to allow for nanoscale manipulations in the future.

注意:我老板Prof. Saggere的手指
Manipulating tiny objects is very important in assembling and characterizing micro- and nanoscale objects, as well as studying biological cells and tissue. At present, most devices for doing this are microelectromechanical "tweezers" that consist of two "legs" typically joined at one end. These instruments are limited because they can only open and close to grasp an object without being able to move it from one place to another. To accomplish the latter task, the tweezers would need to be mounted on other positioning stages capable of twisting and rotating, which would make the system bulky and cumbersome.

Now, Laxman Saggere and Sandeep Krishnan of the University of Illinois in Chicago have come up with a novel solution to this problem. Their micromanipulator system contains multiple, coordinated fingers that can grasp and move objects from one location to another in a limited, defined boundary on a flat surface. The researchers can actuate each finger independently and precisely control the motion of a fingertip on the order of a few nanometres. The device contains four symmetrically placed fingers, but this number could be increased in the future to enhance the manipulator's dexterity, as well as enlarge the area in which an object can be moved, say the duo.

Saggere and Krishnan made their device using conventional micromachining techniques: "An important aspect of the device geometry is that it is a monolithic structure with various parts connected through flexible members," explains Saggere. "Hence the entire structure can be microfabricated at once on a chip without the need for assembling any of the parts separately."

Saggere and Krishnan say the new device could find use in the micro-factories of the future. "The combined functionality of grasping and positioning make the device ideal for aligning and assembling randomly placed microscale and, eventually, nanoscale objects," Saggere told nanotechweb.org. "The device could also be used to manipulate biological cells for applications such as cellular patterning."

The team now plans to improve its proof-of-concept device. This will include interfacing it with appropriate control systems to perform the manipulations; improving the fingertip design for nanoscale applications (for instance, by attaching carbon nanotubes to the tips); and extending the design concept so the instrument can work in 3D and not just on flat surfaces.

The researchers reported their results in J. Micromech. Microeng..

Thursday, February 22, 2007

Thank You For Loving Me

By: Bon Jovi & Jon Bon Jovi
Thank you for loving me

It's hard for me to say the things
I want to say sometimes
There's no one here but you and me
And that broken old street light
Lock the doors
We'll leave the world outside
All I've got to give to you
Are these five words when I

Chorus:
Thank you for loving me
For being my eyes
When I couldn't see
For parting my lips
When I couldn't breathe
Thank you for loving me
Thank you for loving me

I never knew I had a dream
Until that dream was you
When I look into your eyes
The sky's a different blue
Cross my heart
I wear no disguise
If I tried, you'd make believe
That you believed my lies

Chorus:
Thank you for loving me
For being my eyes
When I couldn't see
For parting my lips
When I couldn't breathe
Thank you for loving me

You pick me up when I fall down
You ring the bell before they count me out
If I was drowning you would part the sea
And risk your own life to rescue me

Solo

Lock the doors
We'll leave the world outside
All I've got to give to you
Are these five words when I

Chorus:
Thank you for loving me
For being my eyes
When I couldn't see
You parted my lips
When I couldn't breathe
Thank you for loving me

When I couldn't fly
Oh, you gave me wings
You parted my lips
When I couldn't breathe
Thank you for loving me

Tuesday, February 20, 2007

Waiting On The World To Change

Waiting On The World To Change

me and all my friends
we're all misunderstood
they say we stand for nothing and
there's no way we ever could
now we see everything that's going wrong
with the world and those who lead it
we just feel like we don't have the means
to rise above and beat it

so we keep waiting
waiting on the world to change
we keep on waiting
waiting on the world to change

it's hard to beat the system
when we're standing at a distance
so we keep waiting
waiting on the world to change
now if we had the power
to bring our neighbors home from war
they would have never missed a Christmas
no more ribbons on their door
and when you trust your television

what you get is what you got
cause when they own the information, oh
they can bend it all they want

that's why we're waiting
waiting on the world to change
we keep on waiting
waiting on the world to change

it's not that we don't care,
we just know that the fight ain't fair
so we keep on waiting
waiting on the world to change

and we're still waiting
waiting on the world to change
we keep on waiting waiting on the world to change
one day our generation
is gonna rule the population
so we keep on waiting
waiting on the world to change

we keep on waiting
waiting on the world to change

John Mayer:

After a short-lived stint at the Berklee College of Music, where he had a "great learning experience, but not because of class," John Mayer set down roots in Atlanta, where his music career hit the ground running. After one year in Atlanta, he released his debut solo album, Inside Wants Out, in 1999. At the same time, he became a regular in the Atlanta club circuit, playing a steady stream of shows at venues like Eddie's Attic.

Monday, February 19, 2007

etc and et al 区别

方舟子大虾,打假这么牛,写的论文这么多,居然不会用这两个英文小词,居然和本人4年前写论文时的困惑出奇的一致"et al"是个什么意思?看人家怎么写,照猫画虎也整一个 "et al"。真是英雄所见略同!特摘Dictionary of English中比较,以自勉!

etc, this is an abbreviation of the Latin et cetera, meaning 'and other things'. Some people say that it should not be used with lists of people, or to mean 'and so forth' when referring to events or actions: The children laughed, shouted, ran about, etc. However, its use in these contexts is well established, although et al is more polite when referring to people (this is an abbreviation of the Latin et alii, meaning 'and others').

The more important question is whether you should use these abbreviations at all. They are useful for notes and on forms, but look out of place in ordinary writing; better to begin a list of examples with such as or for example, or to follow it with and so on, and so forth, or (with people) and others. Whatever form you use, make sure that you give some idea of what the other items might be.

In a sentence such as there are worms etc in the garden, etc could refer to almost anything: worms, beetles, woodlice, and so on suggests other creepy-crawlies, while: creatures such as worms, spiders, and frogs suggests a much wider range of wildlife. This means that you have to know what you mean: etc and its equivalents are often used when people are not sure, or cannot be bothered to think about, what they wish to include. Remember the c in et cetera is pronounced s. The et is sometimes incorrectly pronounced ek. Note also that etc and et al can be written with or without a full stop.

Monday, February 12, 2007

My Favorite Music

Let me be your hero

Would you dance . . . if I asked you to dance?
Would you run . . . and never look back?
Would you cry . . . if you saw me crying?
Would you save my soul tonight?

Would you tremble . . . if I touched your lips?
Would you laugh . . . Oh please tell me this.
Now would you die . . . for the one you love?
Hold me in your arms tonight.

I can be your hero babeee.
I can kiss away the pain.
I will stand by you forever.
You can take my breath away.

Would you swear . . . that you'll always be mine?
Would you lie? . . . Would you run and hide?
Am I in too deep? . . . Have I lost my mind?
I don't care . . . you're here tonight!

I can be your hero babeee.
I can kiss away the pain.
I will stand by you forever.
You can take my breath away.

Ohhh . . . I just wanna hold you.
I just wanna hold you . . . Oh yeah!
Am I in too deep? . . . Have I lost my mind?
Well I don't care . . . you're here tonight!

I can be your hero babeee.
I can kiss away the pain . . . Oh yeah!
I will stand by you forever.
You can take my breath away.

I can be your hero.
I can kiss away the pain.
And I will stand by you . . . forever.
You can take my breath away.
You can take my breath away.

I can be your hero.

Sunday, February 11, 2007

MEMS Research Groups

Stanford University

Stanford Microfluidics Laboratory

Stanford Transducers Lab

Main Page - Stanford Microsystems Laboratory

Khuri-Yakub Ultrasonics Group

Melosh Group Web Page

MemsFrame

China’s Influence in Africa Arouses Some Resistance

By MICHAEL WINES Published: February 10, 2007 New York Times

JOHANNESBURG, Feb. 9 — China is often depicted as a juggernaut of sorts, its untroubled and unfettered rise into the ranks of global powers a fact that lesser nations can only watch with awe and trepidation. On Friday, President Hu Jintao of China completed a 12-day tour of Africa that suggested the reality was more nuanced.

【典故 Juggernaut: A deity in Hinduism, considered a deliverer from sin. His image is carried on a large wagon in an annual procession in India, and according to legend the wagon crushed worshipers who threw themselves under it. 克利须那神,在印度东部普利进行的一年一度的游行,其神像被载于巨车或大型马车上,善男信女甘愿投身死于其轮下。】

More than that, the visit tested a basic tenet of China’s economic relations: that business is business, and what a partner nation’s people think about it is not China’s — or the world’s — preoccupation.

【总体而言,纽约时报对于中国的描述都是带贬义色彩,尤其该评论第一二段】

Mr. Hu swept through eight nations, among them some of China’s closest African allies, largest trading partners and most prominent objects of Chinese investment. He left behind a multibillion-dollar trail of forgiven debts, cheap new loans and pledges of schools and cultural centers, tokens of affection for a continent of strategic economic importance to Beijing’s future.

Yet in Zambia, Mr. Hu was greeted with public disdain, and forced to cancel one appearance, even as he showered more than $800 million in gifts and investments on the nation, one of the world’s poorest. In Namibia, a decades-old ally, a newspaper and human rights activists assailed China’s foreign policy as selfish and lacking morality.

In South Africa, a generally warm visit was clouded by President Thabo Mbeki’s recent warning that Africa risked becoming an economic colony of China, and by Johannesburg’s major newspaper, which devoted a full page this week to a scalding critique of China’s record on human rights and labor rights.

Mr. Hu’s stop in Sudan, where China has extensive oil interests, reignited criticism that Beijing has helped shield its ally and oil supplier from global outrage over attacks on civilians in Darfur.

Mr. Hu also met his share of flag-waving supporters, of course, and the official parts of his trip — the meetings and agreement-signings with heads of state — were a diplomatic and commercial success. Most African heads of state like China, which supported many of their liberation movements when liberation was not fashionable. And they like Mr. Hu, whose views on sovereignty, human rights and development are frequently closer to theirs than are those of Western governments.

But an undercurrent of disquiet accompanied Mr. Hu’s barnstorming. Mostly, it came not from heads of state, but from the people they rule, some of whom resent China’s growing influence here — for economic, racial and ideological reasons.

“It’s important to note the obstacles the Chinese are running into” in Africa, said Bates Gill, a leading China scholar at the Center for Strategic and International Studies in Washington. “It has a lot to do with their unfamiliarity with working in countries that have a vibrant private sector and civil society. These guys in the Chinese Embassy, they don’t understand that.”

China is not yet an overwhelming presence in Africa. The juggernaut image aside, China imports less African oil, invests less money and spends less on aid than does the United States or Europe. As an African trading partner, China ranks third, behind the United States and France, and much of that trade is in oil purchased from Sudan, Angola and Nigeria, not in goods made by African workers.

Unlike most other nations, however, China is frequently seen here as coveting Africa for its oil, gold and other valuable minerals and as a dumping ground for cheap Chinese goods — not for its people or talents. Mr. Mbeki said as much in December, warning in a speech that Africa’s relationship to China as an exporter of ore and oil and importer of finished goods threatened to become “a replication of that colonial relationship” between Europe and its African possessions a century ago.

True or not, the perception has been telling. In Zimbabwe, Zambia and elsewhere in southern Africa, an influx of Chinese shopkeepers and street traders has pushed locals into bankruptcy. South African textile workers lost tens of thousands of jobs after the 2005 expiration of a global trade agreement allowed cheaper Chinese goods — including knockoffs of traditional African prints — to flood the country. Angry trade unions called for retaliatory boycotts of shops selling Chinese goods.

Anti-Chinese sentiment has mushroomed in Zambia since 2005, when an explosion at a Chinese-owned copper mine killed at least 46 workers and spawned complaints of unsafe working conditions and poor environmental practices. In last year’s presidential election, the populist challenger to President Levy Mwanawasa based part of his campaign on a pledge to curb Chinese influence in the country.

This month, Mr. Hu canceled a visit to Zambia’s Copperbelt Province, in the nation’s north, apparently because of the threat of protests.

For some foreign powers in Africa, such snubs are part of the territory; both the United States and Europe are regularly assailed for agriculture policies that are said to stunt African farm exports. One reason China has been welcomed into Africa, analysts say, is it can serve as a counterbalance to American influence now that the Soviet Union has vanished from the scene and Russia is far less active in the region.

But while popular dissent is old hat to Westerners, it is less so to the Chinese, for whom foreign relations and domestic policies alike are shaped by governments — not activists, lobbies or public opinion.

Having claimed a bigger role on the African and world stages , Mr. Hu is now reaping the first bitter fruits of pretension to leadership. One test comes in Sudan, where he must reconcile China’s doctrine of noninterference in other nations’ affairs with the outcry over the killings of civilians in Darfur. In Khartoum, he gave Sudan a $13 million interest-free loan to build a new presidential palace, but also said it was “imperative” to halt the deaths in Darfur.


Flow of tiny bubbles mimics computer circuitry

Flow of tiny bubbles mimics computer circuitry

A colored montage of a ring oscillator used in the microfluidic computer developed by researchers at MIT. Starting with top left image, and reading left to right, the yellow bubble flows around the ring until it reaches and joins a stream of bubbles.

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The team, based at MIT's Center for Bits and Atoms, reports that the bubbles in their microfluidic device can carry on-chip process control information, just like the electronic circuits of a traditional microprocessor, while also performing chemical reactions. The work will appear in the Feb. 9 issue of Science.

"Bubble logic merges chemistry with computation, allowing a digital bit to carry a chemical payload. Until now, there was a clear distinction between the materials in a reaction and the mechanisms to control them," said co-author Neil Gershenfeld, director of the Center for Bits and Atoms and associate professor of media arts and sciences.

Microfluidics allow scientists to create tiny chips where nanoliters of fluids flow from one part of the chip to another, undergoing controlled chemical reactions in different parts of the chip and replacing the conventional test tubes and glassware used for chemistry for centuries.

The technology has the potential to revolutionize large-scale chemical analysis and synthesis, environmental and medical testing and industrial production processes, but applications outside of the laboratory have been limited so far by the external control systems-valves and plumbing-required for its operation.

But now, the MIT researchers are able to control microfluidic chips via the interactions of bubbles flowing through microchannels, eliminating the need for external controls. "Now you can program what's happening inside the lab on a chip, by designing bubble logic circuits that function just like their electronic counterparts," said Manu Prakash, Gershenfeld's co-author and graduate student.

Controlling chemical reactions will likely be a primary application for the chips, according to the researchers. It will be possible to create large-scale microfluidic systems such as chemical memories, which store thousands of reagents on a chip (similar to data storage), using counters to dispense exact amounts and logic circuits to deliver them to specific destinations.

Other applications include combinatorial synthesis of many compositions at the same time, programmable print heads that can deposit a range of functional materials, and sorting biological cells.

The researchers modeled their new microfluidic chips on the architecture of existing digital circuits. But instead of using high and low voltages to represent a bit of information, they use the presence or absence of a bubble. They report on nitrogen bubbles in water, but any other combinations of materials that don't mix would work, such as oil and water.

In the Science paper they demonstrate all of the elements needed for any new logic family, including gates, memories, amplifiers and oscillators. The speed of operation is about 1,000 times slower than a typical electronic microprocessor, but 100 times faster than the external valves and control systems used in existing microfluidic chips. Gershenfeld and Prakash anticipate that its invention will allow existing circuit designs (and designers) to work in the domain of microfluidics.

MEMS related publication

  1. Analytical Chemistry
  2. Applied Physics Letters
  3. Biomedical Microdevices
  4. Biosensors and Bioelectronics
  5. IEEE JMEMS
  6. IEEE Transactions on Biomedical Engineering
  7. Japanese Journal of Applied Physics
  8. Journal of Micromechanics and Microengineering
  9. Lab on a Chip
  10. Microfluidics and Nanofluidics
  11. Nano Letters
  12. Nature
  13. Nature Biotechnology
  14. Nature Materials
  15. Nature Methods