ahmad054’s Blog

Welcome to blog of Ahmad S. Aziz. I am a Teaching Assitant in Departement of Physics. I hope you could get an advantage using this blog.

Molecules that arrange themselves into predictable patterns on silicon chips could lead to microprocessors with much smaller circuit elements.

MIT researchers coaxed tiny, chainlike molecules to arrange themselves into complex patterns, like this one, on a silicon chip. Previously, self-assembling molecules have required some kind of template on the chip surface — either a trench etched into the chip, or a pattern created through chemical modification. But the MIT technique instead uses sparse silicon “hitching posts.” The molecules attach themselves to the posts and spontaneously assume the desired patterns.
Image: Yeon Sik Jung and Joel Yang
The features on computer chips are getting so small that soon the process used to make them, which has hardly changed in the last 50 years, won’t work anymore. One of the alternatives that academic researchers have been exploring is to create tiny circuits using molecules that automatically arrange themselves into useful patterns. In a paper that appeared Monday in Nature Nanotechnology, MIT researchers have taken an important step toward making that approach practical.

Currently, chips are built up, layer by layer, through a process called photolithography. A layer of silicon, metal, or some other material is deposited on a chip and coated with a light-sensitive material, called a photoresist. Light shining through a kind of stencil — a “mask” — projects a detailed pattern onto the photoresist, which hardens where it’s exposed. The unhardened photoresist is washed away, and chemicals etch away the bare material underneath.

The problem is that chip features are now significantly smaller than the wavelength of the light used to make them. Manufacturers have developed various tricks to get light to produce patterns smaller than its own wavelength, but they won’t work at smaller scales.

The obvious way to continue shrinking chip features would be to use beams of electrons to transfer mask patterns to layers of photoresist. But unlike light, which can shine through a mask and expose an entire chip at once, an electron beam has to move back and forth across the surface of a chip in parallel lines, like a harvester working along rows of wheat. “It’s like the difference between writing by hand and printing a page all at once,” says Karl Berggren, the Emanuel E. Landsman Associate Professor of Electrical Engineering, who along with Caroline Ross, the Toyota Professor of Materials Science and Engineering, led the new work. The slow, precise scanning of electron-beam lithography makes it significantly more expensive than conventional optical lithography.

Hitchin’ posts

Berggren and Ross’ approach is to use electron-beam lithography sparingly, to create patterns of tiny posts on a silicon chip. They then deposit specially designed polymers — molecules in which smaller, repeating molecular units are linked into long chains — on the chip. The polymers spontaneously hitch up to the posts and arrange themselves into useful patterns.

The trick is that the polymers are “copolymers,” meaning they’re made of two different types of polymer. Berggren compares a copolymer molecule to the characters played by Robert De Niro and Charles Grodin in the movie Midnight Run, a bounty hunter and a white-collar criminal who are handcuffed together but can’t stand each other. Ross prefers a homelier analogy: “You can think of it like a piece of spaghetti joined to a piece of tagliatelle,” she says. “These two chains don’t like to mix. So given the choice, all the spaghetti ends would go here, and all the tagliatelle ends would go there, but they can’t, because they’re joined together.” In their attempts to segregate themselves, the different types of polymer chain arrange themselves into predictable patterns. By varying the length of the chains, the proportions of the two polymers, and the shape and location of the silicon hitching posts, Ross, Berggren, and their colleagues were able to produce a wide range of patterns useful in circuit design.

One of the two polymers that the MIT researchers used burns away when exposed to a plasma (an electrically charged gas), while the other, which contains silicon, turns to glass. The glass layer could serve the same purpose that a photoresist does in ordinary lithography, protecting the material beneath it while that around it is etched away.

Free expression

Dan Herr, the director of nanomanufacturing science research at the Semiconductor Research Corporation, an industry and academic research consortium, says that four or five years ago, his organization polled engineers to determine the seven fundamental shapes that self-organizing molecules would have to be able to assume in order to be useful for circuit manufacture. Since then, he says, researchers have gotten molecules to self-assemble into all seven shapes. But to do so, they’ve “changed the chemistry on the surface or etched down a trench in the surface and used that as a channel for the self-assembling process,” Herr says. Since Berggren and Ross’s technique requires no such channels to guide the self-assembling molecules, it reduces the need for electron-beam lithography. According to Herr, “That will save tremendously in terms of throughput” — that is, the efficiency with which chips can be manufactured.

Much more research is required, however, before self-assembling molecules can provide a viable means for manufacturing individual chips. Nearer term, Berggren and Ross see the technique’s being used to produce stamps that could impart nanoscale magnetic patterns to the surfaces of hard disks, or even to produce the masks used in conventional lithography: today, state-of-the art masks for a single chip require electron-beam lithography and can cost millions of dollars. In the meantime, Ross and Berggren are working to find arrangements of their nanoscale posts that will produce functioning circuits in prototype chips, and they’re trying to refine their technique to produce even smaller chip features.

-Larry Hardesty-

A new analysis of the structure of silks explains the paradox at the heart of their super-strength, and may lead to even stronger synthetic materials.

Spiders and silkworms are masters of materials science, but scientists are finally catching up. Silks are among the toughest materials known, stronger and less brittle, pound for pound, than steel. Now scientists at MIT have unraveled some of their deepest secrets in research that could lead the way to the creation of synthetic materials that duplicate, or even exceed, the extraordinary properties of natural silk.

Markus Buehler, the Esther and Harold E. Edgerton Associate Professor in MIT’s Department of Civil and Environmental Engineering, and his team study fundamental properties of materials and how those materials fail. With silk, that means using computer models that help determine the molecular and atomic mechanisms responsible for the material’s remarkable mechanical properties. The models can simulate not just the structures of the molecules but also how they move and interact in relation to each other.

Silk’s combination of strength and ductility — its ability to bend or stretch without breaking — results from an unusual arrangement of atomic bonds that are inherently very weak, Buehler and his team found. Doctoral student Sinan Keten, postdoctoral associate Zhiping Xu and undergraduate student Britni Ihle are co-authors of a paper on the research that was published on March 14 in the journal Nature Materials.

Silks are made from proteins, including some that form thin, planar crystals called beta-sheets. These sheets are connected to each other through hydrogen bonds — among the weakest types of chemical bonds, and a far cry from the much stronger covalent bonds found in most organic molecules. Buehler’s team carried out a series of atomic-level computer simulations that investigated the molecular failure mechanisms in silk. “Small yet rigid crystals showed the ability to quickly re-form their broken bonds, and as a result fail ‘gracefully’ — that is, gradually rather than suddenly,” graduate student Keten explains.

“In most engineered materials” — ceramics, for instance — “high strength comes with brittleness,” Buehler says. “Once ductility is introduced, materials become weak.” But not silk, which has high strength despite being built from inherently weak building blocks. It turns out that’s because these building blocks — the tiny beta-sheet crystals, as well as filaments that join them — are arranged in a structure that resembles a tall stack of pancakes, but with the crystal structures within each pancake alternating in their orientation. This particular geometry of tiny silk nanocrystals allows hydrogen bonds to work cooperatively, reinforcing adjacent chains against external forces, which leads to the outstanding extensibility and strength of spider silk.

One surprising finding from the new work is that there is a critical dependence of the properties of silk on the exact size of these beta-sheet crystals within the fibers. When the crystal size is about three nanometers (billionths of a meter), the material has its ultra-strong and ductile characteristics. But let those crystals grow to five nanometers, and the material becomes weak and brittle.

Buehler says the work has implications far beyond just understanding silk. He notes that the findings could be applied to a broader class of biological materials, such as wood or plant fibers, and bio-inspired materials, such as novel fibers, yarns and fabrics or tissue replacement materials, to produce a variety of useful materials out of simple, commonplace elements. For example, he and his team are looking at the possibility of synthesizing materials that have a similar structure to silk, but using molecules that have inherently greater strength, such as carbon nanotubes.

The long-term impact of this research, Buehler says, will be the development of a new material design paradigm that enables the creation of highly functional materials out of abundant, inexpensive materials. This would be a departure from the current approach, where strong bonds, expensive constituents, and energy intensive processing (at high temperatures) are used to obtain high-performance materials.

This work was supported by the Office of Naval Research, with additional funding from the National Science Foundation, the Army Research Office, the MIT Energy Initiative, and MIT’s UROP and MISTI-Germany programs.

Peter Fratzl, professor in the department of biomaterials in the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany, who was not involved in this work, says that “the strength of this team is their pioneering multi-scale theoretical approach” to analyzing natural materials. He adds that this is “the first evidence from theoretical modeling of how hydrogen bonds, as weak as they might be, can provide high strength and toughness if arranged in a suitable way within the material.”

Professor of biomaterials Thomas Scheibel of the University of Bayreuth, Germany, who was also not involved in this work, says Buehler’s work is of the “highest caliber,” and will stimulate much further research. The MIT team’s approach, he says, “will provide a basis for better understanding of certain biological phenomena so far not understood.”

-David L. Chandler-

New microscopy technique offers close-up, real-time view of how proteins kill bacteria

This image, taken with atomic force microscopy, shows E. coli bacteria after they have been exposed to the antimicrobial peptide CM15. The peptides have begun destroying the bacteria’s cell walls.
Image: Georg Fantner
For two decades, scientists have been pursuing a potential new way to treat bacterial infections, using naturally occurring proteins known as antimicrobial peptides (AMPs) that kill bacteria by poking holes in their cell membranes. Now, MIT scientists have recorded the first real-time microscopic images showing the deadly effects of AMPs in live bacteria.

Researchers led by MIT Professor Angela Belcher modified an existing, extremely sensitive technique known as high-speed atomic force microscopy (AFM) to allow them to image the bacteria in real time. Their method, described in the March 14 online edition of Nature Nanotechnology, represents the first way to study living cells using high-resolution images recorded in rapid succession.

Using this type of high-speed AFM could allow scientists to study how cells respond to other drugs and to viral infection, says Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering and a member of the Koch Institute for Integrative Cancer Research at MIT.

It could also be useful in studying cell death in mammalian cells, such as the nerve cell death that occurs in Alzheimer’s patients, says Paul Hansma, a physics professor at the University of California at Santa Barbara who has been developing AFM technology for 20 years. “This paper is a highly significant advance in the state-of-the-art imaging of cellular processes,” says Hansma, who was not involved in the research.

High speed

Atomic force microscopy, invented in 1986, is widely used to image nanoscale materials. Its resolution (about 5 nanometers) is comparable to that of electron microscopy, but unlike electron microscopy, it does not require a vacuum and thus can be used with living samples. However, traditional AFM requires several minutes to produce one image, so it cannot record a sequence of rapidly occurring events.

In recent years, scientists have developed high-speed AFM techniques, but haven’t optimized them for living cells. That’s what the MIT team set out to do, building on the experience of lead author Georg Fantner, a postdoctoral associate in Belcher’s lab who had worked on high-speed AFM at the University of California at Santa Barbara.

Atomic force microscopy makes use of a cantilever equipped with a probe tip that “feels” the surface of a sample. Forces between the tip and the sample can be measured as the probe moves across the sample, revealing the shape of the surface. The MIT team used a cantilever about 1,000 times smaller than those normally used for AFM, which enabled them to increase the imaging speed without harming the bacteria.

The measurements are performed in a liquid environment, another critical factor in keeping the bacteria alive.

With the new setup, the team was able to take images every 13 seconds over a period of several minutes following treatment with an AMP known as CM15. They found that AMP-induced cell death appears to be a two-step process: a short incubation period followed by a rapid “execution.” They were surprised to see that the onset of the incubation period varied from 13 to 80 seconds.

“Not all of the cells started dying at the exact same time, even though they were genetically identical and were exposed to the peptide at the same time,” says Roberto Barbero, a graduate student in biological engineering and an author of the paper.

Most AMPs act by puncturing bacterial cell membranes, which destroys the delicate equilibrium between the bacterium and its environment. Others appear to target machinery inside the cell. There has been a great deal of interest in developing AMPs as drugs that could supplement or replace traditional antibiotics, but none have been approved yet.

Until a few years ago, it was thought that bacteria could not become resistant to AMPS, but recent studies have shown that they can. The new MIT work could help researchers understand how that resistance develops.

The research was funded by an Erwin-Schrodinger Fellowship, the National Institutes of Health, Army Research Office and Austrian Research Promotion Agency.

-Anne Trafton-

MIT team coaxes polymers to line up, transforming them into materials that could dissipate heat

The new method involves pulling a thin thread of material (top) from a liquid solution (bottom), and in the process the individual polymer filaments, which start out as a tangled mass, become very highly aligned.
Illustration courtesy of Gang Chen
Most polymers — materials made of long, chain-like molecules — are very good insulators for both heat and electricity. But an MIT team has found a way to transform the most widely used polymer, polyethylene, into a material that conducts heat just as well as most metals, yet remains an electrical insulator.

The new process causes the polymer to conduct heat very efficiently in just one direction, unlike metals, which conduct equally well in all directions. This may make the new material especially useful for applications where it is important to draw heat away from an object, such as a computer processor chip. The work is described in a paper published on March 7 in Nature Nanotechnology.

The key to the transformation was getting all the polymer molecules to line up the same way, rather than forming a chaotic tangled mass, as they normally do. The team did that by slowly drawing a polyethylene fiber out of a solution, using the finely controllable cantilever of an atomic force microscope, which they also used to measure the properties of the resulting fiber.

This fiber was about 300 times more thermally conductive than normal polyethylene along the direction of the individual fibers, says the team’s leader, Gang Chen, the Carl Richard Soderberg Professor of Power Engineering and director of MIT’s Pappalardo Micro and Nano Engineering Laboratories.

The high thermal conductivity could make such fibers useful for dissipating heat in many applications where metals are now used, such as solar hot water collectors, heat exchangers and electronics.

Chen explains that most attempts to create polymers with improved thermal conductivity have focused on adding in other materials, such as carbon nanotubes, but these have achieved only modest increases in conductivity because the interfaces between the two kinds of material tend to add thermal resistance. “The interfaces actually scatter heat, so you don’t get much improvement,” Chen says. But using this new method, the conductivity was enhanced so much that it was actually better than that of about half of all pure metals, including iron and platinum.

Producing the new fibers, in which the polymer molecules are all aligned instead of jumbled, required a two-stage process, explains graduate student Sheng Shen, the lead author of the paper. The polymer is initially heated and drawn out, then heated again to stretch it further. “Once it solidifies at room temperature, you can’t do any large deformation,” Shen says, “so we heat it up twice.”

Even greater gains are likely to be possible as the technique is improved, says Chen, noting that the results achieved so far already represent the highest thermal conductivity ever seen in any polymer material. Already, the degree of conductivity they produce, if such fibers could be made in quantity, could provide a cheaper alternative to metals used for heat transfer in many applications, especially ones where the directional characteristics would come in handy, such as heat-exchanger fins (like the coils on the back of a refrigerator or in an air conditioner), cell-phone casings or the plastic packaging for computer chips. Other applications might be devised that take advantage of the material’s unusual combination of thermal conductivity with light weight, chemical stability and electrical insulation.

So far, the team has just produced individual fibers in a laboratory setting, Chen says, but “we’re hoping that down the road, we can scale up to a macro scale,” producing whole sheets of material with the same properties.

Ravi Prasher, an engineer at Intel, says that “the quality of the work from Prof. Chen’s group has always been phenomenal,” and adds that “this is a very significant finding” that could have many applications in electronics. The remaining question, he says, is “how scalable is the manufacturing of these fibers? How easy is it to integrate these fibers in real-world applications?”

This work, which also included Chen’s former graduate students Asegun Henry and Jonathan Tong, was supported by the National Science Foundation and the Department of Energy’s Office of Basic Energy Sciences.
-David L. Chandler-

New discovery shows carbon nanotubes can produce powerful waves that could be harnessed for new energy systems
A carbon nanotube (shown in illustration) can produce a very rapid wave of power when it is coated by a layer of fuel and ignited, so that heat travels along the tube.
Graphic: Christine Daniloff

A team of scientists at MIT have discovered a previously unknown phenomenon that can cause powerful waves of energy to shoot through minuscule wires known as carbon nanotubes. The discovery could lead to a new way of producing electricity, the researchers say.

The phenomenon, described as thermopower waves, “opens up a new area of energy research, which is rare,” says Michael Strano, MIT’s Charles and Hilda Roddey Associate Professor of Chemical Engineering, who was the senior author of a paper describing the new findings that appeared in Nature Materials on March 7. The lead author was Wonjoon Choi, a doctoral student in mechanical engineering.

Like a collection of flotsam propelled along the surface by waves traveling across the ocean, it turns out that a thermal wave — a moving pulse of heat — traveling along a microscopic wire can drive electrons along, creating an electrical current.

The key ingredient in the recipe is carbon nanotubes — submicroscopic hollow tubes made of a chicken-wire-like lattice of carbon atoms. These tubes, just a few billionths of a meter (nanometers) in diameter, are part of a family of novel carbon molecules, including buckyballs and graphene sheets, that have been the subject of intensive worldwide research over the last two decades.

A previously unknown phenomenon

In the new experiments, each of these electrically and thermally conductive nanotubes was coated with a layer of a reactive fuel that can produce heat by decomposing. This fuel was then ignited at one end of the nanotube using either a laser beam or a high-voltage spark, and the result was a fast-moving thermal wave traveling along the length of the carbon nanotube like a flame speeding along the length of a lit fuse. Heat from the fuel goes into the nanotube, where it travels thousands of times faster than in the fuel itself. As the heat feeds back to the fuel coating, a thermal wave is created that is guided along the nanotube. With a temperature of 3,000 kelvins, this ring of heat speeds along the tube 10,000 times faster than the normal spread of this chemical reaction. The heating produced by that combustion, it turns out, also pushes electrons along the tube, creating a substantial electrical current.

Combustion waves — like this pulse of heat hurtling along a wire — “have been studied mathematically for more than 100 years,” Strano says, but he was the first to predict that such waves could be guided by a nanotube or nanowire and that this wave of heat could push an electrical current along that wire.

In the group’s initial experiments, Strano says, when they wired up the carbon nanotubes with their fuel coating in order to study the reaction, “lo and behold, we were really surprised by the size of the resulting voltage peak” that propagated along the wire.

After further development, the system now puts out energy, in proportion to its weight, about 100 times greater than an equivalent weight of lithium-ion battery.

The amount of power released, he says, is much greater than that predicted by thermoelectric calculations. While many semiconductor materials can produce an electric potential when heated, through something called the Seebeck effect, that effect is very weak in carbon. “There’s something else happening here,” he says. “We call it electron entrainment, since part of the current appears to scale with wave velocity.”

The thermal wave, he explains, appears to be entraining the electrical charge carriers (either electrons or electron holes) just as an ocean wave can pick up and carry a collection of debris along the surface. This important property is responsible for the high power produced by the system, Strano says.

Exploring possible applications

Because this is such a new discovery, he says, it’s hard to predict exactly what the practical applications will be. But he suggests that one possible application would be in enabling new kinds of ultra-small electronic devices — for example, devices the size of grains of rice, perhaps with sensors or treatment devices that could be injected into the body. Or it could lead to “environmental sensors that could be scattered like dust in the air,” he says.

In theory, he says, such devices could maintain their power indefinitely until used, unlike batteries whose charges leak away gradually as they sit unused. And while the individual nanowires are tiny, Strano suggests that they could be made in large arrays to supply significant amounts of power for larger devices.

The researchers also plan to pursue another aspect of their theory: that by using different kinds of reactive materials for the coating, the wave front could oscillate, thus producing an alternating current. That would open up a variety of possibilities, Strano says, because alternating current is the basis for radio waves such as cell phone transmissions, but present energy-storage systems all produce direct current. “Our theory predicted these oscillations before we began to observe them in our data,” he says.

Also, the present versions of the system have low efficiency, because a great deal of power is being given off as heat and light. The team plans to work on improving that efficiency.

Ray Baughman, director of the Nanotech Institute at the University of Texas at Dallas, who was not involved in this work, calls the research “stellar.”

The work, Baughman says, “started with a seminal initial idea, which some might find crazy, and provided exciting experimental results, the discovery of new phenomena, deep theoretical understanding, and prospects for applications.” Because it uncovered a previously unknown phenomenon, he says, it could open up “an exciting new area of investigation.”

-David L. Chandler-

Dalam sejarah dunia abad lalu, ada pemimpin dunia yang sangat terkenal akan kekuatan visinya yaitu John F. Kennedy. Di hadapan Konggres Amerika pada tahun 1961 dia mengungkapkan visinya bahwa bangsa Amerika harus bisa mencapai bulan sebelum akhir dekade itu.

Di tengah bangsa Amerika yang lagi limbung sebenarnya visi ini jauh melampaui jamannya. Visi ini muncul ketika bangsa Amerika ragu apakah jalan hidup yang mereka pilih sudah benar, apakah bukannya komunis yang benar karena saat itu komunis lagi menghebohkan dengan keberhasilan Soviet meluncurkan satelit yang mengorbit bumi. Bahkan bangsa Amerika lagi nggumun-nggumun-nya dengan keberhasilan soviet mengirim kosmonot Yuri Gagarin ke antariksa.

Namun sekitar delapan tahun kemudian, meskipun JFK sendiri sudah meninggal – visinya teralisasikan dengan sejarah Neil Amstrong dan Buzz Aldrin sebagai manusia-manusia pertama yang menginjakkan kakinya di bulan pada tanggal 20 Juli 1969.

Jadi visi lebih penting ketimbang sumber daya dan kondisi yang melingkungi manusia itu sendiri. Dengan sumber daya melimpah tetapi tidak didukung oleh visi yang jelas – maka sumber daya yang melimpah ini tidak akan banyak manfaatnya.

Sebaliknya dengan sumber daya yang terbatas dan dengan lingkungan yang tidak sepenuhnya kondusif sekalipun, pemimpin yang mempunyai visi yang kuat akan bisa mengeluarkan rakyatnya dari penderitaan dan bahkan bisa menjadi bangsa pemenang – meskipun tidak harus tercapai pada saat dia memimpin.

Lantas bagaimana kita tahu apakah kita sudah memiliki visi yang jelas atau kita baru sekedar bermimpi ?. Bedanya terletak pada jabaran-nya. Visi yang jelas dapat dijabarkan menjadi Mission, Goals, Strategies dan Action Plans sampai sedetilnya. Sedangkan mimpi tidak perlu penjabaran, Anda bisa saja mimpi lagi menikmati liburan di Paris tetapi berangkatnya naik sepeda dari Depok – namanya juga mimpi, boleh-boleh saja dan tidak perlu penjelasan detil.

Perbedaan antara visi dan mimpi ini pulalah yang antara lain membedakan sedikit karyawan yang benar-benar pindah kwadrant menjadi pengusaha, dengan mayoritas karyawan yang tetap menjadi karyawan sampai pensiun – padahal sejak awal bekerja yang mayoritas ini juga bervisi (sebenarnya masih mimpi) menjadi pengusaha. Golongan yang pertama menjabarkan visinya dan berbuat (action plans) maka sampailah apa yang di-visi-kannya; golongan kedua tidak bermuat apa-apa dengan mimpinya – maka mimpi tetap menjadi mimpi.

Dalam hal visi ini, sebagai umat Islam kita sesungguhnya punya contoh tauladan yang jauh lebih agung dari John F. Kennedy. Tauladan kita adalah bapak para nabi yaitu Nabi Ibrahim A.S. Bayangkan ditengah padang pasir yang gersang tidak ada pepohonan, di tempat yang sangat jauh dari keramaian manusia – nabi Ibrahim sudah memiliki visi yang sangat jelas akan seperti apa tempat itu nantinya. Visi ini dituangkan dalam do’a-do’a-nya yang diabadikan di Al-Qur’an antara lain sebagai berikut :

Dan (ingatlah), ketika Ibrahim berdoa: Ya Tuhanku, jadikanlah negeri ini negeri yang aman sentosa, dan berikanlah rezeki dari buah-buahan kepada penduduknya yang beriman di antara mereka kepada Allah dan hari kemudian… “. (QS 2 :126)

Ya Tuhan kami, sesungguhnya aku telah menempatkan sebahagian keturunanku di lembah yang tidak mempunyai tanam-tanaman di dekat rumah Engkau (Baitullah) yang dihormati, ya Tuhan kami (yang demikian itu) agar mereka mendirikan shalat, maka jadikanlah hati sebagian manusia cenderung kepada mereka dan beri rezkilah mereka dari buah-buahan, mudah-mudahan mereka bersyukur. (QS 14:137).

Kini ribuan tahun kemudian, visi itu benar-benar terwujud. Kita bisa menikmati buah-buahan apa saja di Mekkah, meskipun buah-buahan itu sendiri tidak ditanam disana. Buah-buahan, makanan, pakaian dan berbagai kebutuhan manusia mengalir bak air bah dari seluruh dunia ke tempat yang di visikan nabi Ibrahim tersebut diatas. Lebih dari itu manusia yang berduyun-duyun ke Mekkah juga mayoritasnya memiliki satu tujuan saja yaitu menyembah Allah semata yang dimanifestasikan dalam bentuk sholat.

Nah, kalau Kennedy saja yang tidak membaca petunjuk Al-Qur’an bisa membawa bangsanya mencapai bulan. Kita yang dituntun dengan petunjuk dan contoh yang sempurna dari Al-Qur’an dan Hadits – sudah seharusnya dapat berbuat lebih dari yang dilakukan oleh JFK.

Bukan hanya petunjuk dan contoh yang sangat komprehensif yang kita punya, tetapi juga kita dibekali dengan do’a-do’a yang matsur seperti yang dilafalkan Nabi Ibrahim tersebut diatas.

Ayo sekarang kita semua, mulai dari diri kita – bangun dari mimpi-mimpi kita dan mulai membangun visi sambil tidak berhenti untuk terus berdo’a. Semoga Allah menunjuki jalanNya untuk kita semua…Amin.

-Muhaimin Iqbal-

For neuroscientists, one of the best ways to study brain activity is with a scanning technique called functional magnetic resonance imaging (fMRI), which reveals blood flow in the brain.

However, although fMRI is a powerful tool for identifying brain regions that are active during a particular task, it offers only an indirect view of what’s happening. Measuring a more direct indicator of neural activity, such as concentrations of neurotransmitters (brain chemicals that carry messages between neurons) could be much more valuable.

Now, for the first time, MIT and Caltech researchers have come up with a new type of fMRI sensor that can do just that. The two sensors, described in the Feb. 28 online edition of Nature Biotechnology, detect dopamine — a neurotransmitter involved in learning, movement control and many other brain processes.

“This new tool connects molecular phenomena in the nervous system with whole-brain imaging techniques, allowing us to probe very precise processes and relate them to the overall function of the brain and of the organism,” says Alan Jasanoff, an associate professor of biological engineering at MIT and senior author of the paper.

Dopamine holds particular interest for neuroscientists because of its role in motivation, reward, addiction and several neurodegenerative conditions, including Parkinson’s disease. The new sensors could help scientists learn more about how dopamine acts in the brain and in other organs, says Andrew Alexander, co-director of the Brain Imaging Core at the University of Wisconsin at Madison.

“Previously we really haven’t had specific biomarkers for looking at things like dopamine or other chemical neurotransmitters” with MRI, says Alexander.

Designing a new sensor

Conventional fMRI measures blood flow in the brain by tracking hemoglobin, the molecule that carries oxygen. Hemoglobin has an iron atom at its core that binds to oxygen. When bound to oxygen, hemoglobin’s magnetic properties change in a way that can be detected with MRI.

“fMRI is an extremely powerful technique for studying how the brain functions, and it’s the only way to obtain spatial information and information about when things are happening,” says Jasanoff, who also has appointments in the Departments of Brain and Cognitive Sciences and Nuclear Science and Engineering, and in the McGovern Institute for Brain Research at MIT.

However, the spatial and temporal information is imprecise. Researchers can detect increased activity in a certain area, but they can’t see what the activity is, nor can they get a high-resolution picture of which neurons are involved.

A more detailed picture of brain activity could emerge with MRI sensors specific to particular neurotransmitters. The MIT team designed sensors specifically for dopamine, but their technique could be used to create sensors for other neurotransmitters or even unrelated molecules of biological interest.

To build the new sensors, the MIT team worked with chemical engineers at Caltech, using an approach called “directed evolution.” They started with a protein called cytochrome P450, an enzyme found in most organisms that is paramagnetic (meaning it can become weakly magnetic when exposed to a magnetic field). Using a technique called error-prone PCR, which is a faulty version of the way cells naturally replicate their genes, they generated a large collection of different mutated forms of the gene.

Each mutated gene was placed into an E. coli bacterium, which produced the mutated protein. The researchers then tested each protein for its ability to bind dopamine. At the end of each round, they took the best candidate and mutated it again for a new round of improvement. At the end of five rounds, they had two sensors that would bind strongly to dopamine but not to other neurotransmitters.

“You want it to be specific to dopamine — you don’t want it to bind to dopamine and half a dozen other things,” says Jasanoff.

In studies of rats, the researchers showed that the sensor can effectively detect dopamine in the brain. However, in its current form, the dopamine probe must be injected into the brain, and the imaging is limited to the site of injection.

Bruce Jenkins, director of neurochemical imaging at the Martinos Center for Biomedical Imaging at MGH, says the new probe is “very cleverly designed,” but points out that an important challenge is yet to come: getting the molecule to cross the layer of cells that separates the brain from circulating blood. “Trying to get a charged protein across the blood-brain barrier is very tricky,” he says.

The MIT team hopes to overcome that obstacle by applying barrier disruption techniques used historically to deliver chemotherapeutic agents to the brain. They will also try to genetically program brain cells to express the sensor, so it doesn’t have to be injected.

They plan to adapt the directed evolution strategy to look for sensors for other neurotransmitters as well. If successful, that could help researchers in Jasanoff’s lab and elsewhere create a better wiring diagram of how different brain regions and neurotransmitters work together to yield behavior such as learning, memory, addiction and movement.

“We hope to develop probes that target different parts of the mechanism, allowing us to piece these systems together in a way that’s noninvasive,” says Jasanoff.

-Anne Trafton- Graphic: Patrick Gillooly-

CAMBRIDGE, Mass. — For years, biologists have wondered how it is possible that not every person who carries a mutated gene expresses the trait or condition associated with the mutation. This common but poorly understood phenomenon, known as incomplete penetrance, exists in a wide range of organisms, including humans.

Many mutations in genes that are linked to diseases, including Parkinson’s disease and Type 1 diabetes, are incompletely penetrant. Some of this variation may be due to environmental factors and the influence of other genes, but not all: It has been shown that genetically identical organisms living in the same environment can show variability in some incompletely penetrant traits.

Now, a team of MIT biophysicists has demonstrated that some cases of incomplete penetrance are controlled by random fluctuations in gene expression.

“It’s not just nature or nurture,” says Alexander van Oudenaarden, leader of the research team and a professor of physics and biology at MIT. “There is a random component to this. Molecules bounce around and find each other probabilistically. It doesn’t work like clockwork.”

In a study of intestinal development of C. elegans, a small worm, the team was able to pinpoint specific fluctuations that appear to determine whether the mutant trait is expressed or not.

The work, published in Nature on Feb. 18, may also be relevant to human diseases that display incomplete penetrance, such as Parkinson’s disease and Type 1 diabetes, says van Oudenaarden. For example, knowing the specific points in cellular pathways that are most important in controlling a cell’s response to mutation could give drug designers better targets for new therapies.

How they did it: The team studied the embryonic development of the digestive tract of C. elegans. The tract starts out as a single cell and eventually becomes 20 cells in the adult worm. That process is initiated by a gene called skn-1, which activates a series of other genes. Most of those genes code for transcription factors, which bind to DNA and turn on additional genes.

The team first characterized normal progression of intestine development, using a probe the team members developed that binds to messenger RNA inside cells, allowing them to count the number of copies of a particular messenger RNA sequence. (Messenger RNA carries DNA’s instructions to the cell’s protein-building machinery.)

They then studied worms with a mutation in skn-1, and found that some of the worms developed normal digestive tracts while others failed to develop a digestive tract. It appears that the controlling factor is the number of copies of mRNA produced by a gene called end-1, one of the genes activated by skn-1. The number of end-1 mRNA strands varied greatly in embryos with the mutation: In those with a number above a certain threshold, development proceeded normally; if the number was below the threshold, no digestive tract developed.

It appears that evolution has produced networks of genes that smooth out the effects of those fluctuations, which are revealed only when there is a mutation in the pathway, says van Oudenaarden.

Next steps: Van Oudenaarden plans to use the same technique to study mammalian colon stem cells, in hopes of figuring out whether random fluctuations in gene expression influence the mutations that can cause cancer. If he can show that random fluctuations in a particular gene appear to be subject to the same threshold effect that he saw in C. elegans embryonic development, it could give drug designers new targets.

Source: “Variability in gene expression underlies incomplete penetrance in multicellular development,” Arjun Raj, Scott Rifkin, Erik Andersen, Alexander van Oudenaarden. Nature, February 18, 2010.

Funding: National Institutes of Health, National Science Foundation, Burroughs-Wellcome Fund.

-Anne Trafton-

Ada berita menarik yang bisa Anda baca pada harian Republika yang terbit hari ini (02/03/2010) bahwa IMF menyerukan untuk meninggalkan US$. Berita ini sendiri tentu saja valid karena merujuk pernyataan Dominique Strauss-Kahn, the head of the International Monetary Fund pada jum’at pekan lalu.

Bukannya saya lebih tahu atau lebih pinter dari pimpinan tertinggi IMF tersebut; namun kalau Anda baca tulisan saya hampir 6 bulan lalu dengan judul Tinggalkan Dollar Selagi Sempat , maka Anda akan tahu bahwa seruan atau wacana yang dilontarkan oleh orang nomor 1 di IMF ini adalah hal yang sudah seharusnya dilakukan dan tidak akan mengejutkan Anda.

Masalahnya yang perlu diwaspadai oleh umat dan juga bangsa-bangsa lain di dunia adalah – ada apa dibalik pernyataan ini. Mengapa baru sekarang wacana mengganti US$ dimunculkan ?. Dan apa pengganti US$ yang mereka pikirkan ?.

Saya mencoba menduga-duga apa kira-kira jawaban atas dua pertanyaan tersebut diatas. Mengenai mengapa baru sekarang wacana ini dimunculkan; dugaan saya karena mereka (para petinggi IMF) juga tahu kalau US$ tidak akan survive dalam waktu yang lebih lama lagi – wacana ini dimunculkan untuk semacam sosialisasi ke dunia akan kondisi yang sangat mungkin akan terjadi.

Nampaknya mereka ingin memperbaiki sejarah kegagalan IMF pertama, ketika terjadi kejutan Nixon Shock Agustus 1971 – dimana secara sepihak dan mendadak –Nixon mengguncang Dunia dengan meninggalkan emas sebagai rujukan mata uang Dollar-nya. Kali ini mereka ingin masyarakat dunia tahu dulu – bahwa Dollar berkemungkinan gagal (lagi) dan dunia tidak akan bisa mengandalkannya.

Lantas mengapa mereka ‘berbaik hati’ memberi isyarat pada dunia bahwa US$ akan gagal ?; sederhana – karena mereka juga masih ingin (tetap) memimpin dunia dengan aturannya. Ingat ketika IMF gagal pertama dengan kejadian Nixon Shock Agustus 1971; penggantinya tetap IMF juga hanya ‘undang-undang’-nya yang berganti dari Breton Woods Agreement (1945) menjadi Article of Agreement of IMF yang ditanda tangani di Smithsonian Institute – December 1971. Dari lokasi penanda tangananan ini saja sebenarnya umat Islam yang cerdas sudah harus tahu siapa dibelakang mereka ini dan untuk kepentingan siapa program-program mereka dibuat.

Pertanyaan kedua mengenai apa pengganti US$ yang mereka pikirkan ?. terungkap dari pernyataan Dominique bahwa pengganti US$ sebagai reserve currency yang akan datang adalah “similar to but distinctly different from the IMF’s special drawing rights, or SDRs”.

SDR adalah reserve asset yang diciptakan oleh IMF tahun 1969; awalnya nilai 1 SDR setara dengan 0.888671 gram emas – yang seharusnya saat itu juga bernilai 1 US$. Setelah kejadian Nixon Shock tersebut diatas, ‘uang’ SDR yang tadinya setara emas tersebut-pun berganti menjadi setara dengan sekeranjang mata uang - mata uang kuat dunia. Untuk saat ini isi keranjang tersebut terdiri dari US$ , Poundsterling, Euro dan Yen.

Lantas berapa nilai SDR tersebut sekarang ?, per kemarin (01/03/2010) 1 SDR nilainya setara dengan US$ 1.52771 atau kalau dibelikan emas hanya dapat 0.0425 gram. Jadi uang SDR itu-pun kini nilainya tinggal sekitar 1/20 dari nilai awal ketika diperkenalkan 41 tahun lalu.

Maknanya apa ini semua ?, bila US$ sebagai reserve asset diganti dengan SDR bentuk baru sekalipun (yang dikatakan Dominique sebagai similar but distinctly different dengan SDR yang sekarang) – tetap tidak dapat menjadi reserve asset yang sesungguhnya – karena nilainya juga mengalami keruntuhan sebagaimana sekeranjang mata kertas uang yang digunakan untuk menghitung nilainya.

Kita umat Islam tidak seharusnya menggunakan timbangan yang mereka ciptakan; kita memiliki timbangan yang adil sepanjang masa – yaitu emas, perak, gandum , kurma dan benda-benda riil yang memiliki nilai instrinsik lainnya. Waktunya kita mengikuti petunjuk jalan kita sendiri dan tidak mengikuti mereka memasuki lobang biawak berikutnya. Wa Allahu A’lam.

-Muhaimin Iqbal-

Ada pemandangan baru yang sejak beberapa tahun ini mulai marak di café, restaurant, food court, bandara, terminal dan bahkan di emperan Masjid-masjid. Pemandangan ini adalah orang-orang yang tidak mengenal usia asyik ber-internet dengan berbagai keperluannya. Kebanyakan mungkin (masih) untuk sekedar main-main atau membuang waktu percuma; tetapi tidak sedikit pula diantara mereka yang sedang serius bekerja menangani hal-hal yang sangat produktif.

Para pekerja yang tidak lagi tergantung pada tempat dan waktu ini, mereka bisa bekerja kapan saja dan dimana saja asal bisa connect dengan internet . Melalui internet inipula pekerjaan mereka dilaporkan keatasannya, di share dengan mitra kerja, ditindak lanjuti sub-ordinate-nya; di response kliennya dlsb.dlsb. pekerja generasi baru inilah yang disebut pekerja Digital Nomad.

Bagi perusahaan yang meng-optimalkan pekerja Digital Nomad ini bisa sangat diuntungkan karena tidak harus menyediakan kantor yang mahal, biaya transportasi, listrik dlsb. Bagi pekerja Digital Nomad sendiri, ini juga menjadi peluang tersendiri untuk bisa bekerja sesuai selera kapan dan dimana dia suka - hemat waktu dan biaya. Penghematan ini mulai dari waktu perjalanan ke kantor sampai biaya pakaian. Bagi pemerintah ini juga bisa menghasilkan penghematan yang luar biasa dalam bentuk berkurangnya kemacetan, kebutuhan listrik, bahan bakar dlsb.

Dahulu ketika saya masih ngantor di pusat kota misalnya, setiap hari saya sekitar tiga jam pergi pulang di mobil. Dengan saya memutuskan untuk tidak bekerja di pusat kota Jakarta pada saat usia produktif; kepadatan lalu lintas Jakarta telah berkurang satu mobil setiap hari; 15 liter bensin dihemat setiap hari; sekian CO2 terkurangi.

Bila langkah ini diikuti oleh seribu orang, maka kepadatan lalu lintas Jakarta akan berkurang secara significant. Apalagi kalau yang mengikutinya 1 juta orang. Maka inilah menurut saya salah satu cara Jakarta melawan kemacetan dan polusi udara. Bukan hanya kemacetan dan bahan bakar yang dihemat, tetapi juga dari makanan dan pakaian.

Bila Anda bekerja di kantor – ongkos makan siang Anda cenderung jauh lebih mahal ketimbang keluarga Anda yang di rumah. Pakaian juga demikian, bila Anda eksekutif secara berkala Anda harus membeli baju baru, dasi dan bahkan jas untuk bekerja. Ini semua tidak Anda perlukan bila Anda pekerja Digital Nomad. Bekerja dengan sarungan-pun jadilah, karena sarung ini adalah salah satu pakain nasional kita yang selama ini termarginalkan.

Apakah ini mudah dilakukan ?, mudah sih tidak karena menyangkut perubahan budaya yang luar biasa. Tetapi bagi pimpinan-pimpinan kantor yang berwawasan kedepan, bisa jadi inilah peluang Anda untuk membawa perusahan atau instansi Anda untuk unggul di era teknologi yang mau tidak mau kita telah memasukinya. Bila Anda tidak segera mulai, sedangkan pesaing Anda memulai lebih dahulu – kemungkinan besar Anda akan kalah bersaing dalam efisiensi dan akan ditinggalkan oleh tenaga-tenaga terbaik Anda. Mengapa demikian ?.

Kalau ditanya diri kita masing-masing; besar kemungkinan kita sebenarnya ingin bekerja secara bebas tidak dikungkung tempat dan waktu. Nah kalau tenaga terbaik Anda ditawari oleh pesaing Anda dengan system kerja bebas semacam ini, besar peluangnya dia akan terpengaruh. Sebaliknya kecil sekali kemungkinan Anda bisa merekrut tenaga-tenaga yang sudah terbiasa kerja secara Nomad untuk nongkrong di kantor tertentu pada jam tertentu.

Apakah pekerjaan ala Digital Nomad ini hanya cocok untuk pekerjaan seperti penulis, wartawan, designer, programmer dan sejenisnya ?; Sebelum saya ikut menerjuninya dahulu saya juga berpendapat demikian. Namun setelah saya bener-bener terjun di dalamnya; ternyata bekerja dengan model Digital Nomad, dapat pula dilakukan untuk pekerjaan-pekerjaan yang dahulu tidak terbayangkan – toko emas –pun seperti GeraiDinar dapat dijalankan fully secara Digital Nomad. Kadang saya bekerja di rumah, kadang di Masjid, kadang di Mall; kadang di Mobil bahkan sering dari kandang kambing di Jonggol yang sudah internet ready.

Pekerjaan seperti yang Anda lakukan sekarang-pun sangat mungkin ditangani secara Digital Nomad bila Anda (dan atasan Anda bagi yang punya atasan) mau berpikir serius. Hampir seluruh pekerjaan kantoran pada umumnya, bisa dilakukan oleh para Digital Nomad sekarang; hanya sebagain kecil saja yang belum bisa dilakukan seperti pekerjaan customer services, dan pekerjaan lain yang membutuhkan kehadiran fisik – tetapi inipun jumlahnya akan terus menurun sejalan dengan kemajuan teknologi.

Apakah Anda siap untuk pekerjaan Digital Nomad ini ?, tes-nya sederhana saja. Drive atau penggerak produktifitas Anda ada dalam diri Anda atau ada diluar diri Anda ?. Bila Anda memiliki self drive untuk bekerja optimal tanpa harus di tongkrongi atasan Anda ; maka insyallah Anda siap untuk memasuki jenis pekerjaan para Digital Nomad.

Siapa sih yang tidak ingin bekerja deket rumah, bisa mengatur waktu secara fleksibel, bisa memiliki quality time untuk keluarga…?; lebih-lebih bagi kaum wanita. Dengan Digital Nomad Anda bisa berkarir sampai manapun – tanpa harus meninggalkan fitrah ke-ibu-an Anda untuk dekat dan mendidik anak-anak Anda kapan-pun mereka membutuhkannya. Insyaallah…

-Muhaimin Iqbal -