Think of a Zero. Chances are your mind didn't land on laser beams, drift to Doppler effects, or free associate atoms of gas flying through the air at the greatest of ease.
That's what Dr. Nir Davidson and his colleagues from the Institute's Physics of Complex Systems Department are doing -- giving lots of thought to zero. For them, absolute zero is absolutely worthy of consideration.
This is a story about turning science fiction into science function. The application of Davidson's work, cooling and trapping atoms, could be employed, for example, in building highly-accurate atomic clocks. Waves of cooled atoms could be focused, using "lenses" of laser light to create a kind of pen or etching tool, to "draw" electronic circuits much smaller than those existing today. They could be used to measure atomic constants, to confirm or deny various generalizations in quantum theory, and to research some of the basic symmetry laws of nature.
There's just one problem: Making atoms cool their heels long enough to study them. While we may neither feel nor see them, atoms of gas are constantly flying about at an incredible speed, making it extremely difficult to research their properties, let alone isolate them for application. It's difficult to conceive of, but within a completely still room, gas atoms are flying about at an average speed of 620 mph (1,000 km/h). Even at a temperature of only 3°K (-460°F, or -270°C), the atoms are still moving at about 62 mph (100 km/h).
That's where absolute zero comes in. Only at the temperature of about one-thousandth of a degree above absolute zero do the atoms "calm down" slightly and slow to a speed less than that of the pace of a walking human.
One method of cooling gas atoms is based on six "laser cannons" that "shell" groups of atoms from all directions and "catch" them almost without motion in a vacuum. Light particles, known as photons, hit the atom like a ping pong ball hitting a billiard ball. If enough ping pong balls hit amoving billiard ball in the direction contrary to its line of motion, its progress will be arrested until making it come to a full stop.
More accurately, the laser beams directed toward the atoms have a wavelength (color) slightly longer than the wavelength of the light absorbed by the atoms being cooled. Thus, the atoms at rest hardly "feel" the hits by the photons, whereas the atoms moving toward one of the beams in an attempt to leave the area they are being confined in, find themselves involved with the Doppler effect. The Doppler effect "shortens" the wavelength of the laser beam so that its photons are absorbed by the atom, which slows down its progress. This method is known as "Doppler cooling."
Like everything else in life, the Doppler cooling method also has its limitations. As a result, more advanced laser cooling methods have been developed over the years, such as the Sisyphus and the Raman cooling methods. In this way scientists have succeeded in cooling atoms to a temperature of less than one-third of a millionth of a degree above absolute zero.
To exploit these cooled atoms, the researchers must store them for as long a period of time as possible hopefully, for several seconds in a special trap made out of light rays. The "industry" of making light traps capable of trapping atoms istoday one of the hottest frontiers of science.
Dr. Davidson, who is working on this front, says that one should differentiate between the "illuminated" traps in which atoms of material are attracted and trapped in the illuminated area of the trap, and the dark traps, in which the atoms are repelled by the light and are trapped in the darkened part of the trap. Dr. Davidson himself first demonstrated the "dark trap" as part of his postdoctoral work at Stanford University, California, in the laboratory of Prof. Steve Chu. Chu won this year's Nobel Prize in Physics.
The "dark trap" is similar to a kind of "room" whose walls are made of laser beam light, in the center of which is darkness. The gas atoms located in the dark area try to escape from the trap, but each time they hit one of the walls of light, they're repelled.
The main advantage of the "dark trap" as opposed to the regular light traps, derives from a significant reduction in the distortions the light has on the trapped atoms (both in changing their energy levels and in the random distribution of photons from the trapping laser).
Until now, Dr. Davidson has succeeded, using his dark trap, in reducing these distortions by a factor of one thousand or more, over several seconds. His current research is directed toward further reducing the distortions, in order to extend containment time and to improve the trap's properties.
The field of science is, in a manner of speaking, about performing research until scoring a hit. In the matter of atoms of gas, cooling and trapping them, it means Dr. Davidson and team are going for zero.
1. Nerve signals from the brain go down the spine to the front and hind limbs
2. Damage to the spine interrupts the signals to the hind legs, causing their paralysis
3. Immune system cells (red) try to heal the damage, but they are blocked by a protective mechanism of the central nervous system (green )
4. A segment of the peripheral nerve (purple) is incubated with the immune cells and "activates" them
5. "Activated" immune cells are returned to the damaged site
6. They manage to overcome the protecitve mechanism an partially heal the damage
7. As a result, the paralysis is partially overcome
Weizmann Institute scientists have managed to partially heal the damaged spinal cords of laboratory animals, according to a study reported in the July issue of Nature Medicine. A team led by Prof. Michal Schwartz of the Neurobiology Department used an innovative treatment which allowed rats to regain partial movement in their hind legs that had been paralyzed by damage to the spine.
"The results of our experiments are promising," says Prof. Schwartz. "However, for the moment, they have been achieved only in rats. A lot of additional research still needs to be done before the new treatment is available to humans."
It has long been known that lower animals, such as fish, can repair damaged fibers in the central nervous system the spinal cord and the brain and restore lost function. In contrast, mammals, including humans, can only repair injuries to the peripheral nerves, while injuries to the brain or spine leave them permanently paralyzed or otherwise handicapped.
The new approach is based on Schwartz's theory which states that the loss of this reparability occurred in the course of evolution, and is due to a unique relationship between the central nervous and immune systems. More specifically, Schwartz believes this loss was probably dictated by the need to protect the mammalian brain from the effects of the immune system. While immune cells normally help to heal damaged tissue, their access to the brain would disrupt the complex and dynamic neural networks that build up during an individual's lifetime.
Generally, when tissue damage occurs, immune cells known as macrophages swarm to the injured site where they remove damaged cells and release substances that promote healing. The central nervous system of mammals is different in this regard: When damaged, it is not effectively assisted by the immune system.
Schwartz's team discovered that this is because the mammalian central nervous system has a mechanism that suppresses the macrophages. As a result, macrophages are recruited to central nervous system injuries at a lower rate, and those that are recruited fail to become optimally "activated" and effective.
These findings led to a series of experiments with rats in the course of which the researchers managed to overcome the limited ability of the damaged central nervous system to recruit and activate the macrophages. They isolated macrophages and incubated them in a test tube in the presence of a damaged peripheral nerve. The macrophages, which received the distress signals of the damaged peripheral nerve, became activated.
At this stage, the researchers returned the activated macrophages to the damaged site in the central nervous system of the paralyzed rat. The transplanted macrophages created a growth-inducing environment around the damaged tissue. As a result of the treatment, the rats were able to regain parti al motor activity in their previously paralyzed legs. They were able to move their hind legs and several animals were even able to place their weight upon them.
A major innovative aspect of such treatment lies in promoting the animal's own self-repair mechanism. In fact, the new treatment offers the option of using the animal's own cells for this purpose.
Further research is necessary to see if this approach will work in higher animals, such as humans
Yeda Research & Development Co. Ltd., the Weizmann Institute's technology transfer arm, has submitted patent applications for the new treatment. In order to promote this research and develop it furt her for possible clinical use, Yeda has entered into a licensing agreement with Proneuron Biotechnology Ltd., a start-up company located in the Kiryat Weizmann Industrial Park adjacent to the Institute.
Even the most experienced cyberscientist can easily get lost in the vast labyrinth of data on human genes available on the Internet thanks to the international Human Genome Project. Now Weizmann Institute scientists have created GeneCards, a new on-line database and software tool that provides scientists, biotechnologists, physicians and teachers with fast and convenient access to the genetic information they need.
GeneCards is updated on an ongoing basis by software "robots" intelligent computer programs that search relevant genomic databases and websites, then organize and present the data in a concise and easy-to-read format. This automatic procedure, known as data mining, guarantees that when you access GeneCards, you're always looking at the most up-to-date information.
GeneCards was created by a team that included postdoctoral fellows Drs. Michael Rebhan and Vered Chalifa-Caspi and doctoral student Gustavo Glusman. The team is headed by Prof. Doron Lancet of the Molecular Genetics Department, head of the Institute's Genome Center, and Dr. Jaime Prilusky of the Biological Services, head of Weizmann's Bioinformatics Unit. Currently, it also includes postdoctoral fellow Dr. Liora Yaar and engineer Marilyn Safran.
GeneCards features a page, or card, for every human gene. Each card contains a particular gene's vital statistics, such as its official name, the protein it encodes, its functions in the cell, its location on a chromosome, and information about the diseases caused by its mutations. It may also list similar genes found in organisms other than humans or provide links to other relevant sites based on bioinformatics, the dynamic new discipline that combines biology with computer science.
One of GeneCards' most striking features is its "intelligent interface" which helps searchers reach more efficiently the data they need. For instance, if a query produces no results, the database may suggest a way to reformulate the question, correct a spelling error, or provide tips on where else to look for information.
Currently, GeneCards contains information on over 7,000 human genes that have already been clearly identified and named by scientists deciphering the human genome. It is now being augmented to include tens of thousands of new genes that have been identified, but whose function is not yet known. By the time the Human Genome Project is completed (probably around the year 2002), the database will encompass all 80,000-100,000 human genes.
By fall 1998, the GeneCards site averaged about 22,000 hits per month from around the globe. It's generated special interest among Israeli and foreign biotechnology firms interested in developing new drugs based on human gene information.
Not everyone gets the opportunity to work at his passion. Even as a child in Safed, one of the oldest cities in Israel, Mahmoud Huleihil treasured the purity of his natural surroundings. As an adult, he ventured to another pristine place, Sde Boker in the Negev desert, where he performed research on solar energy. What attracts him to that particular kind of energy? "It's pure," he says, as if this should be obvious to anyone who would compare a day on the beach to a walk in a smog-filled city.
But it's purely expensive, too. Arriving six months ago as a postdoctoral fellow at the Weizmann Institute, Dr. Mahmoud Huleihil of the Environmental Sciences and Energy Research Department is working to solve this kink in solar energy. "We've got to convince politicians," says Dr. Huleihil, "...and that's usually done through the pocketbook."
The divisive factor is the construction of a new solar power plant: Why invest money in building an additional plant when the old system works just fine, thank you? Simulating solar power plant construction on his computer, and programming it to suit experimental needs, the objective is to bring cost, as well as sunlight, down to earth.
The heliostat, a type of mirror, accounts for about 50 percent of the plant's total cost, according to senior scientist Dr. Abraham Kribus, Dr. Huleihil's postdoctoral advisor. [Dr. Kribus holds the Recanati Career Development Chair of Energy Research.] Maximizing the mirrors' efficiency will make it possible to minimize their cost. The solar plant's field area, occupied principally by the mirrors, would shrink proportionately.
One of Huleihil's challenges is to address the mirrors' tendency to deviate slightly from their set position. When this happens, the mirrors miss their target: the solar receiver, which absorbs their sum energies. But in a field of hundreds of mirrors, how can you find the one that's "faking" it?
The computer, which sets the mirrors' angles according to the time of day, can't tell the difference; judging by its screen, you wouldn't even know anything was amiss. Solution: Dr.Huleihil is working on a computer program which will spot deviant behavior by calculating the different light intensities shone on four "smart cameras" placed around the receiver.
Solar energy may, in fact, be even more efficient than other forms of energy. One of the basic precepts of thermodynamics is this: The higher the temperature, the greater the efficiency. The sun's temperature is approximately 6,000° C (10,832° F). Using solar energy, scientists can draw the sun's heat to earth at a temperature of 2,000° C (3,632° F), much higher than the temperature obtained when heating with fossil fuel. (Preliminary calculations to determine whether using solar energy in this way is worthwhile are currently being carried out by Weizmann scientists.) Yet, even with its advantages in mind, solar energy is costly.
However, as Dr.Huleihil points out, in assessing the price of an energy source, one must not look only at the accounts book one must look at nature and the environment as well.
When it comes to do-it-yourself, some people aren't content with merely assembling bookshelves or twisting a coathanger to provide a quick-and-dirty solution.
It all started when Professor Daniel Zajfman of the Weizmann Institute's Particle Physics Department consulted with his German colleagues at the Max Planck Institute. He and his team were using an enormous ring in Heidelberg for storing molecular ions and cooling them to their ground state.
"Two years ago, I came back from a trip to Germany thinking 'Wouldn't it be terrific to have our own machine?'" says Zajfman, who was made associate professor last year. So with his sights set on the 56-meter ion storage ring, he returned to the Institute and created his own version that fits on a desktop.
The research into molecular ion collisions carried out by Zajfman provides vital information about the birth and composition of stars. Zajfman's job: to return ions to their ground state, i.e., the lowest energy and least vibrating state in which a particle can exist. This greatly enhances Zajfman's data on the structure and dynamics of molecular ions, and is of particular interest to astro-, plasma and planetary physicists.
However, with only one week's use of the German ring every few months, there was tremendous pressure to perform only those experiments whose success was practically guaranteed. Being in possession of some kind of device in Israel to which he could have unlimited access would greatly ease the strain.
It took Zajfman-as-problemsolver three months to determine the parameters of how and exactly what to build, given that his small lab could not accommodate a huge 56-meter ring. And what of cost? Ouch: in the region of millions of dollars. What he eventually designed turned out to be a brand new type of ion storage device, the 50-centimeter-long electrostatic bottle.
The bottle, whose price tag is tens of thousands of dollars rather than millions is comprised of two mirrors which bounce the molecular ions back and forth. "It doesn't perform in the same way as the large ring," explains Zajfman, "but it stores molecular ions so that you can cool them."
There is only one such device in existence today, and Zajfman has just begun his first experiments using it. This bottle could also be a boon for others who wait months for beam time on the storage ring at Heidelberg or the only other such rings in the world, in Japan, the U.S., Sweden and Denmark.
Having his own ion storage bottle has not actually meant that the Belgian-born Zajfman (who made aliyah in 1979) has stopped his regular pan-European flights. His collaboration with German physicists is very valuable, and certain experiments, e.g., involving collisions between molecular ions and electrons, still require the large and expensive devices found only at the Max Planck facility. But with equipment "at home" in the lab, he can now attempt, freely, procedures whose results are less predictable.
"If you have a big machine and you only have one beam time every few months, you're not really going to try crazy ideas because of the price and the great effort," he says. "On a small machine you can try crazy stuff. For physicists, crazy things are what make things happen."
"We're developing a new therapy for cancer treatment. We injected a mouse with a non-toxic chemotherapy drug that you make toxic by illuminating the tumor. When you turn off the light, that's it," explains Professor Yoram Salomon, Biological Regulation Department, about the research he is conducting with Professor Avigdor Scherz, Plant Sciences Department.
The drug he is referring to is a water soluble derivative of chlorophyll, which is the green pigment of plants. Chlorophyll is the light-harvesting molecule, the antenna of this planet that harvests solar energy, later transforming it into useable fuels. Scherz and Salomon are taking this molecule and utilizing it for a completely different purpose.
They are applying the chlorophyll to photodynamic therapy, or PDT, a cancer treatment already in common use. The essential element in understanding PDT is that it uses a combination of drugs and light. Simply stated, the drug is injected into the patient's or animal's bloodstream, or directly into the tumor. Then, by exposing only the tumor to light in a controlled manner, the drug is activated and becomes toxic to cancer. Result: The drug-and-light combination destroys tumor cells while having little effect on healthy tissues.
However, states Salomon, "For the drugs used today, there are limitations." That's why their work is so important. PDT as it is currently practiced in a clinical setting is effective only against relatively flat and thin tumors, such as certain types of skin and bladder cancers. The new tandem approach promises to destroy tumors, the bulky, solid tumors that until now have been impenetrable by light.
Another limitation for patients undergoing standard PDT is that they must avoid sunlight for weeks following treatment because their skin becomes overly sensitive to strong light. In contrast, the "green" materials, which are modified to make them soluble in water, clear faster from the body. That may allow patients to tolerate outdoor light within a few days after treatment with less concern that the photosensitive materials will harm their skin.
"If successful, in the future our 'green' PDT could be a powerful new tool in the struggle against cancer," says Scherz. "The great advantage of this treatment over conventional chemotherapy is that the drug's action is confined to the illuminated tumor site, so that the damage to healthy tissues is minimized and side effects are significantly reduced," reports Salomon.
The materials were shown to kill cancer cells in tissue culture and they have successfully eradicated relatively large malignant melanoma tumors in mice. In tissue culture, they have destroyed other cancer cell types, including breast and colon.
More Good News
The scientists are also exploring the potential use of the new materials as antimicrobial drugs. This application of the chlorophyll derivatives may be particularly important in view of the growing problem of bacterial resistance to antibiotics. A recent study showing that chlorophyll derivatives effectively kill disease-causing bacteria was published in the December 1997 issue of Photochemistry and Photobiology, the journal of the American Society for Photobiology.
The development of "green" PDT for clinical use is being funded and will be clinically tested in a year or so by the Dutch company Steba Beheer NV, which has been granted a worldwide license for the product by Yeda Research and Development Co. Ltd., the Weizmann Institute's technology transfer arm.
Caveat: Don't be taken in by size. That's the rather pointed message delivered courtesy of the cone snail. Though small, its venom has a deadly, zooming-in quality that makes these creatures especially noxious. Dr. Michael Fainzilber of the Biological Chemistry Department is part of the effort to turn these killers into healers.
"My uncle told me never to touch cone snails when I was a child, so I'd pick them up carefully and collect them," he recalls.
Fainzilber's childhood interests in Africa carried into adulthood in Israel, and into an important discovery: He has uncovered one of the cone snails' paralyzing, lethal proteins and followed its deadly sequence of destruction. These proteins are unique in their specificity. Specialists in pharmacology and biomedicine are taking note, as specificity is the name of their game.
Many of the Institute's scientists wend their way to Israel in an intriguing fashion; Fainzilber's story is especially captivating. Born in Tanzania, then a British colony to which Holocaust refugees were sent, he'd go swimming in the waters off its eastern coast in search of interesting shells.
Faintly conscious of a land called Israel, to which his father had been refused entry by the British after fleeing Europe, he did not feel like the son of outcasts. Tanzania, after all, was so rich in the natural treasures which feed a child's curiosity. "We had lions near our backyard," he says.
The world's troubles would soon have an effect on his life as well. Independence in Tanzania in 1961 led to a shift towards communism. One day in 1972, Fainzilber's parents told him that they were all going off on a "holiday." Their destination was Israel, by then independent for almost 25 years. Luckily for the 10yearold Fainzilber, they settled in Haifa, the main port city of Israel where he could keep up his snorkeling.
Since that time, one could say he's been "snorkeling his way" to the Weizmann Institute. When asked to name the oceans or seas in which he hasn't gone diving, Fainzilber is stumped. More than just a pastime, his diving has meshed with his scientific work, bringing him to the Weizmann Institute this past year.
With the help of his friends at the Free University of Amsterdam and UC San Francisco, Fainzilber has already discovered one paralyzing protein in the snail's venom and sequenced it. What this toxic protein does is latch on to a very specific site on the nerve cell of its prey, pulling open one of its channels. The channels, situated on the cell membrane, act as "doors" to the cell, letting particles in only at the turn of a "key." The key opening this particular channel is normally a specific combination of four neuropeptides.
This toxic protein dodges the channel's four-peptide "combination-lock" and opens the channel to streams of ion particles. The cell's innards become a free-for-all, the ion inflow unregulated. Since ion particles set off a signal instructing muscle contraction, the result of their unregulated flow is constant muscle contraction in other words, paralysis.
The scientific importance of Fainzilber's discovery may lie in the special features of its target. "The channel targeted by the toxin is a pacemaker channel, meaning it regulates rhythmic processes," says Dr. Fainzilber. "The challenge now is to find similar toxins that could target other pacemaking channels, for example, in the heart. Then we may be able to engineer them to do something useful. One could call it an effort to turn swords into plowshares."
When you have an X-ray, what happens to your DNA? When a cancer patient undergoes radiation treatments, how much is too much?
The precise answers to these questions may dwell inside a tiny gas bubble.
Damage to DNA is believed to be the major cause of cell mutation and in some instances, death. A group of physicists whose work overlaps the realm of biology, headed by Professor Amos Breskin of the Particle Physics Department, got to thinking: Just how do you analyze radiation's effects on something as small as DNA if no particle detector has the sensitivity to determine it?
Possible answer: If the DNA were in gaseous form, it would then be considerably expanded in size and thus easier to determine change. And that is how the tiny gas bubble was born. A simulated fragment of DNA in gaseous form, it's only a millimeter in size but one million times the size of our DNA.
Prof. Amos Breskin, together with departmental colleagues Drs. Rachel Chechik and Sergei Shchelmelinin, have succeeded in constructing the first detector that permits measuring the effects of radiation on a DNA-like gas bubble.
Prior to this, scientists throughout the world had constructed gas models of cells and chromosomes. But because cells and chromosomes are much larger than DNA, those models could not predict potential damage to the diminutive DNA. The new particle detector, 100 to 1,000 times more precise than prevailing techniques, could fulfill the task.
How does the detector work? When radiation penetrates the cell, it breaks molecular bonds in the DNA. Each molecule then separates into an electron (negatively charged) and an ion (in this case, positively charged). This means that the more electrons and ions spotted in a cell, the more bonds have been broken.
The question is, have the DNA double strands both broken too? Once you detect a large concentration of particles in the DNA-like gas bubble, and with it proof that many bonds could have been broken at one particular site, you may have found what you were looking for an irreparable break in the DNA double strands.
Causing these electrons or ions to fly out of the bubble, Prof. Breskin can count them using the new detector. The ion rate of release is a telling indicator of the frequency of reactions which went on between the radiation and the gas and their concentration in the vicinity of the DNA strand. The scientists can then use scaling factors to predict the frequency of interactions in the actual smaller, solid volume of DNA.
The same X-ray or particle beam that enters the bubble, exits it and interacts with a sample of living cells. The cells' rate of destruction is compared with the radiation effect on the DNA gas model. The researchers intend to determine the direct correlation between the radiation dose causing potential, permanent damage to DNA, and cell destruction.
Once the researchers have found the details of the correlation between the two experiments, it will pave the way for more accurate predictions of radiation effects on the living cell.
In treating cancer, the object is to destroy the DNA in tumor cells using as little radiation as possible, so as not to damage the surrounding healthy tissue. "Once you know how much radiation breaks DNA strands, you can better determine how much radiation to expose cancer patients to," says Professor Breskin.
Along with its potential impact on cancer screening and treatment, Prof. Breskin's approach may make safer our personal health by allowing scientists to designate more precise limits on the number of X-rays a person may undergo yearly, including those we are exposed to at the dentist's office and during a routine mammography. Better informed standards on radiation exposure in the workplace could be set.
Breskin's group's research may even affect space programs, clarifying radiation's impact on astronauts. It could lead to new approaches on how best to protect advanced electronic equipment in satellites and other space objects from cosmic radiation.
All of this, thanks to Breskin's little gas bubble.
If you've ever lived in a city and attempted to grow tomatoes in a windowbox, this story is for you. If you just plain like tomatoes or Jonathan Swift, or for that matter, boutiques and designer tags dangling from your jeans, oops, we mean genes, read on. Couture fruits and vegetables rather than pret-a-manger? If the word "mutation" has a certain attractive ring to it, settle back and read awhile.
A tiny tomato, dubbed "Micro-Tom," is making giant strides in genetic engineering. The Lilliputian plant, now adapted for research, is the key to a new method that may speed the process of unraveling the genetic code of plants, making it easier to identify and capitalize on these commercially-valuable genes. The man behind the mutation is Dr. Avraham Levy of the Plant Sciences Department.
Working with Dr. Yoni Elkind of the Hebrew University of Jerusalem and Ph.D. student Rafi Meissner, Levy has taken Micro-Tom, a humble plant bred for city dwellers with limited gardening space, and joined it with a unique combination of technologies in order to speed up mutagenesis, the creation of new mutant plant strains.
Levy is addressing mutagenesis with a major breakthrough in miniature. Levy's Micro-Tom, which puts out fruit twice as fast as conventional tomatoes, cuts in half the time necessary to produce such mutations. Too, it drastically reduces the amount of greenhouse space necessary for cultivating new mutant plant strains, making it easier to work with sizeable plant populations. With the Micro-Tom, Levy can grow up to 1,000 plants per square meter as opposed to five plants per square meter in the case of normal tomatoes. That's more than a 99% reduction in greenhouse space. And its rapid growth cycle allows Levy and team to cultivate four generations per year as opposed to the usual two.
Levy's method also makes mutations easier to analyze. Prevailing techniques, which use chemicals or radiation to create a mutant plant, result in random mutations that are difficult to trace to a particular spot in the plant's genetic code. The new technique differs, marking the plant genome with easily-identified genetic "tags" (a group of readable, genetic characters) that allow Levy to locate the exact spot where a mutation has taken place.
This traceability, together with the use of large plant populations, makes it feasible to identify the function of any plant gene. "If earlier techniques for creating mutations are something like playing the lottery," says Levy, "with this new method, we can buy all the tickets."
In recent years, scientific advances have made it easier to identify genes and their function, creating the tantalizing possibility of a genetic "boutique" where plant breeders may browse among thousands of traits and select genetic material for customizing fruits and vegetables. Previously, before such a boutique would open its doors, each trait in the "inventory" had to be produced in an isolated, living plant a process that required the time-consuming sleuthing of approximately 50,000 genes and an estimated 100,000-plus tomato plants. Enter Levy and team, speedmeisters of the produce fast track. Levy's technique was designed for use on tomatoes, one of the most important crops for the fresh and processed food industries. But the method can be applied to any crop where farmers are interested in engineering new, more marketable strains.
So the next time you're in the supermarket pinching, sniffing, or humming "You say tomayto, And I say tomahto," think of Dr. Levy. His research may lead to a veritable cornucopia of 21st century palatepleasers.
A smooth, friction-free future may be in the offing - for machinery, that is. Prof. Reshef Tenne and his team in the Materials and Interfaces Department have created a new kind of lubricant that promises to cut friction in half. The synthetic material is made of inert, round molecules of tungsten disulfide. Says Tenne: "They just roll against each other and against the machinery parts, and don't stick to anything, like Teflon."
The synthetic molecule has a structure similar to the soccerball-like clusters of carbon atoms called fullerenes, or buckyballs, named after R. Buckminster Fuller, architect of the geodesic dome. Fullerenes were discovered in the last decade when a U.S.-British team of scientists noted that, under certain conditions, carbon atoms will cluster together to form a stable, hollow sphere. The discovery won the researchers the 1996 Nobel Prize in Chemistry.
Initially, it was believed that only carbon, or molecules containing carbon, exhibit this behavior. But in 1992, Tenne and his Institute colleagues succeeded in producing inorganic fullerene-like molecules from tungsten disulfide. Since then, several other inorganic buckyball compounds have been synthesized at the Institute and elsewhere. To Tenne, the properties of the new, inert molecules seemed to have great potential for the development of a new generation of solid lubricants.
Why solid? Liquid lubricants, it turns out, are not appropriate for all environments. They freeze in the extreme cold of outer space and lose their effectiveness in a heated engine and in heavy-load transmission systems. Currently available solid lubricants, even ones made of tungsten or molybdenum disulfides, have drawbacks too.
"Existing solid lubricants contain crystallites, which are shaped like flat platelets and have chemically reactive edges," says Tenne. "In working conditions, they stick to machinery parts and undergo chemical reactions that lead them to decompose and rub off." The parts are then subject to grinding, substantially shortening the lifespan of the machinery.
The Weizmann tungsten disulfide buckyballs get "around" this problem. Being round and inert, they have no edges where the chemical reactions that make other lubricants stick can take place. Since machine parts just roll over them, they make reliable chemical ball-bearings. They wear better, too, because they are made up of many layers, like an onion. If the top layer wears off, the underlying layer continues the lubricating action. These balls are also larger than the carbon fullerenes, thus keeping the metal parts further separated and giving more bounce to resist mechanical pressure.
Prof. Reshef Tenne
Tenne's next challenge was to produce the new material in the laboratory and test it under conditions simulating those prevailing in industry. The results that rolled in proved that this was definitely the right stuff. The new lubricant outperformed all existing solid lubricants, including normal tungsten disulfide and molybdenum disulfide. The synthetic buckyballs caused half the friction and only one-sixth as much wear.
The potential market for this new substance is tremendous. The automobile industry faces ever stricter environmental regulations that require it to reduce pollution and make engines and transmission systems more efficient. In general, earthbound enterprises are looking for ways to conserve resources and cut costs by making machinery last longer. In microelectronics, where minuscule transistors are produced under sterile conditions, solid lubricants are preferred over liquid ones because they cause no contamination of the electric circuitry. And in space, where commercial projects are proliferating, more and more equipment that can function in extreme temperatures will be required.
Currently, the Weizmann Institute laboratory can synthesize about a gram a day of inorganic buckyballs. To get this enterprise moving, it will be necessary to scale up the synthesis to at least a couple of hundred grams daily, a matter for smart engineering. Then a homogenous and stable emulsion of the solid particles in oil and cooling fluids must be formulated. And finally, extensive field tests have to be carried out to ascertain the stability of the lubricant in various environments. Yeda Research and Development Co. Ltd., the Institute's technology transfer arm, has filed patent applications for the new material. Interest in it is being expressed by industrial companies around the world.
Tenne's team was made up of doctoral students Yishay Feldman and Moshe Homyonfer, Dr. Sidney Cohen of the Institute's Chemical Services Unit and Dr. Lev Rapoport and other researchers from the Center for Technological Education in Holon.
This research was funded in part by Yeda Research and Development Co. Ltd; the Israel Ministry of Science; the U.K.-Israel Science and Technology Foundation; the Minerva Foundation, Germany; the NEED International Projects, Japan; and the Petroleum Research Foundation of the American Chemical Society.
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Absolute Zero
That's what Dr. Nir Davidson and his colleagues from the Institute's Physics of Complex Systems Department are doing -- giving lots of thought to zero. For them, absolute zero is absolutely worthy of consideration.
This is a story about turning science fiction into science function. The application of Davidson's work, cooling and trapping atoms, could be employed, for example, in building highly-accurate atomic clocks. Waves of cooled atoms could be focused, using "lenses" of laser light to create a kind of pen or etching tool, to "draw" electronic circuits much smaller than those existing today. They could be used to measure atomic constants, to confirm or deny various generalizations in quantum theory, and to research some of the basic symmetry laws of nature.
There's just one problem: Making atoms cool their heels long enough to study them. While we may neither feel nor see them, atoms of gas are constantly flying about at an incredible speed, making it extremely difficult to research their properties, let alone isolate them for application. It's difficult to conceive of, but within a completely still room, gas atoms are flying about at an average speed of 620 mph (1,000 km/h). Even at a temperature of only 3°K (-460°F, or -270°C), the atoms are still moving at about 62 mph (100 km/h).
That's where absolute zero comes in. Only at the temperature of about one-thousandth of a degree above absolute zero do the atoms "calm down" slightly and slow to a speed less than that of the pace of a walking human.
One method of cooling gas atoms is based on six "laser cannons" that "shell" groups of atoms from all directions and "catch" them almost without motion in a vacuum. Light particles, known as photons, hit the atom like a ping pong ball hitting a billiard ball. If enough ping pong balls hit amoving billiard ball in the direction contrary to its line of motion, its progress will be arrested until making it come to a full stop.
More accurately, the laser beams directed toward the atoms have a wavelength (color) slightly longer than the wavelength of the light absorbed by the atoms being cooled. Thus, the atoms at rest hardly "feel" the hits by the photons, whereas the atoms moving toward one of the beams in an attempt to leave the area they are being confined in, find themselves involved with the Doppler effect. The Doppler effect "shortens" the wavelength of the laser beam so that its photons are absorbed by the atom, which slows down its progress. This method is known as "Doppler cooling."
Like everything else in life, the Doppler cooling method also has its limitations. As a result, more advanced laser cooling methods have been developed over the years, such as the Sisyphus and the Raman cooling methods. In this way scientists have succeeded in cooling atoms to a temperature of less than one-third of a millionth of a degree above absolute zero.
To exploit these cooled atoms, the researchers must store them for as long a period of time as possible hopefully, for several seconds in a special trap made out of light rays. The "industry" of making light traps capable of trapping atoms istoday one of the hottest frontiers of science.
Dr. Davidson, who is working on this front, says that one should differentiate between the "illuminated" traps in which atoms of material are attracted and trapped in the illuminated area of the trap, and the dark traps, in which the atoms are repelled by the light and are trapped in the darkened part of the trap. Dr. Davidson himself first demonstrated the "dark trap" as part of his postdoctoral work at Stanford University, California, in the laboratory of Prof. Steve Chu. Chu won this year's Nobel Prize in Physics.
The "dark trap" is similar to a kind of "room" whose walls are made of laser beam light, in the center of which is darkness. The gas atoms located in the dark area try to escape from the trap, but each time they hit one of the walls of light, they're repelled.
The main advantage of the "dark trap" as opposed to the regular light traps, derives from a significant reduction in the distortions the light has on the trapped atoms (both in changing their energy levels and in the random distribution of photons from the trapping laser).
Until now, Dr. Davidson has succeeded, using his dark trap, in reducing these distortions by a factor of one thousand or more, over several seconds. His current research is directed toward further reducing the distortions, in order to extend containment time and to improve the trap's properties.
The field of science is, in a manner of speaking, about performing research until scoring a hit. In the matter of atoms of gas, cooling and trapping them, it means Dr. Davidson and team are going for zero.