Submitted by Jean Delfiner
Co-Chair of HSTTG

        Joe Sencen started off with a show of a few store-bought demos. First were two auto battery testers; essentially eye-droppers with several ball floats inside. It’s a quick and easy way to gauge density. Next up was his creative use of Lego blocks to demonstrate isotopes. He took one piece of “Blockium” and divided it into its ten component pieces, some which weighed 1, 2, or 3 units. Each type of block was present in a different percentage, and by taking the weighted average you could see the effect of different isotopes on atomic mass. Al Delfiner was next to take the stage, showing off some vintage slide-rules (originally bought at the low price of 19¢). He expressed his dismay that no one is familiar with ratios anymore, which is the foundation for the slide-rule’s operation, and also stressed the importance of teaching students to keep units with their numbers during calculations.
Our guest speaker at this meeting was Doreen Bader, an environmental educator with the NYC Department of Environmental Protection (DEP). Her presentation was an interesting mix between describing New York’s reservoir system and water quality testing and talking about how the DEP educates students about water conservation. She warned us early on that she was big on audience involvement, and within minutes everyone was on their feet stomping their feet as she demonstrated one of the activities she likes to use to describe the water cycle while raising the energy level of the group.

        The sheer size of the New York City water system is staggering. Serving 8 million people, over 1.3 billion gallons are used every day, with 550 billion gallons in reserve in the reservoir system in upstate New York. There are in fact three separate systems, the Croton (which includes the reservoir in Central park and makes up about 10% of the city’s water supply), the Catskill (40%) and the Delaware (50%). There is no active pumping at all, with gravity doing all the work until the water gets to the city. Even there, water can make it up ten stories, but any higher and pumps must be utilized to fill water towers at the top of the high rises. It is actually possible to determine from which reservoir system your water is coming from by testing the specific conductivity, as each system has slight variations in electrical resistance.

        Obviously water quality is a major concern, and we can be proud that New York has one of the best systems in the world. Water is tested daily at multiple sites from the reservoirs themselves to the tributaries, aqueducts, and city testing sites (the over 900 silver DEP boxes you can find on many street corners). Rain or shine, blizzards or worse, DEP workers are out in boats testing our water to insure our safety. Tests are done for color, pH, turbidity, algae, parasites, organic and inorganic chemicals, toxins, bacteria, pesticides, fertilizer, and more. If a single E. coli colony was found, for example, the city would go to a state of “water alert,” the last of which occurred in 1994 when Canadian geese were soiling the water. Faced with the choice between adding more chlorine to the drinking water and finding a way to get rid of the geese, DEP workers took to the water on hovercraft with noisemakers and scared the geese to New Jersey.
The treatment process itself is actually very mild, consisting of a few additives but no filtration or aeration. Chlorine is used for sterilization, and its use has wiped out water-borne illnesses like Cholera. Chlorine gas is bubbled in as the water leaves the reservoir, and the dosage can vary depending on the flow of the water and the temperature. Fluoride is added as well, which is mandated by the Department of Health to help prevent tooth decay. Several other minor additives are also used, such as orthophosphates to coat pipes and prevent contaminants like copper or lead from leaching into the water. If you want your water tested for any reason, you can call 311 and schedule a free appointment where the DEP will test in your building and in the nearby pipes to isolate the problem.

        Ms. Bader outlined her education strategies, including ‘making learning fun,’ using visuals and hands-on activities, addressing different learning styles, and adapting technical information to the classroom. She went over various free workshops that the DEP offers, teaching students about water testing and conservation, ranging from lab visits to more traditional classroom visits. She provided teacher packets for everyone in attendance, with various materials like the New York City Drinking Water Supply and Quality Report, several classroom activities, a “Magic School Bus” special edition book, and many more great items. She said these packets were available for free for anyone interested in full class sets. (Doreen Bader, Research Scientist/Environmental Educator, NYC Dept. of Environmental Protection, Education Office 19th Floor, 5917 Junction Blvd., Flushing, NY 11373, 718-595-3523, <DBader@dep.nyc.gov>.)
This month’s Sargent-Welch VWR International $50 gift certificate door prize went to Melissa Paige, a new science teacher at PS 221 in Queens.
 

        Joe Sencen showed the 6 foot K&E demonstration slide rule that hangs in his lab. Not many of them left since hand held calculators took over. He also showed a string he stretches from the front to the back of his classroom. One end is the Earth and the other is the Sun. On the string are tags (proportionately spaced) to indicate Mercury and Venus. Joe uses this to illustrate the scale of the solar system.
Our guest speaker was Professor Richard Gross from Polytechnic University. He gave us a talk on “Green Chemistry,” an area for which he recently won the Presidential Award. Green Chemistry, as Professor Gross describes it, is the meeting of the two greens: the environment and the bottom line. Not a “blind effort to improve the environment through legislation,” Green Chemistry aims to find novel solutions that actually reduce costs and environmental impact at the same time.
        If scientists can innovate and reduce costs, then everyone wins. Rather than ask for tax rebates or subsidies to implement environmentally sound policies, Professor Gross showed us how by reducing waste and using creative methods, environmentally friendly behavior can actually bring great cost benefits. The aim is to minimize three areas: waste, hazardous materials, and environmental liability. Waste products are paid for twice (once for the initial use and then again to dispose of them) but don’t provide any profit. Hazardous materials are dangerous and raise costs as well. Environmental liability refers to hidden costs that will have to be paid for later.
Increasing efficiency in this fashion can be attained in several ways: safer reactants, catalysis, solvent replacement, and renewable feedstocks are some areas that green chemists have used to streamline reactions. Using old chemistry, harsh dangerous reactions are performed at high temperatures and pressures, and with dangerous toxins. With green chemistry, the same products can be created at low temperatures with simple reactions helped along by natural processes. One example of such innovation is in the creation of Ibuprofen, which previously required a 6-step process that had 66% waste, but under the new Hoechst process can be done in half the steps and only 28% waste.
The use of renewable resources is one of the keystones of green chemistry. Using plant-fixed carbon instead of releasing more carbon dioxide into the atmosphere is essential to curbing the greenhouse effect. Professor Gross showed data that provided clear evidence that human activities are causing climate change, and he warned of future implications such as mass extinctions, disease, natural disasters, and rising sea levels. Bioethanol and Biodiesel are fuels based on carbon sequestration from plants, which are just as energy efficient as their petroleum-based counterparts. Biorefineries can create fuels, solvents, plastics, fibers, and oils all with simple, natural reactions.

        Another area of focus is replacing solvents with supercritical CO2. At its triple-point, carbon dioxide acts as a highly tunable solvent by making small changes in pressure. Supercritical CO2 is easily disposed, stable, and non-polar, but changing the pressure changes its polarity and therefore solvency. Professor Gross said that solvents are a crutch, and much can be done to avoid their use entirely.   In the simplest view of biotech processing, a biomass undergoes hydrolysis to produce sugars and carbohydrates, which in turn undergo fermentation, creating useful materials. Ethanol, which can be made from cellulose, is not just a fuel but also a great starting material to make more useful chemicals. Biodegradable plastics can be formed from microbial fermentation, as can biodiesel fuel. Biodiesel is energy efficient, produces less CO2, and is nontoxic. It remains a little costly, but the cost of producing biodiesel is lowering even as petroleum costs rise to meet it, so it seems to be only a matter of time before biodiesel is more cost efficient as well as energy efficient.

        Green Chemistry represents a meeting between biology and chemistry. Biological systems can utilize sophisticated reactions that are beyond our capability, and by studying and taking advantage of these systems we can improve our own chemical reactions. Professor Gross noted that this was never the way organic chemistry was taught, yet it seems absurd that we don’t learn about the most abundant chemicals (starch, chitin, and cellulose) on the planet. Green Chemistry should be incorporated into the curriculum, showing how alternate processes can produce similar results to more traditional methods. In the production of adipic acid, for example, the chemical route takes several catalysts and very high pressure, whereas the microbial route minimizes chemical reactions in a much more elegant process. The Green Chemistry mindset has to take hold in innovation, and the easiest way to achieve this shift in thinking is to educate our new scientists.

There were two door prizes this month. The first, a Vernier Packet with Graphical Analysis software went to John Flowers, Medgar Evers College, CUNY.  The second was a $50 Sargent-Welsh gift certificate, won by Lou Pataki, Roton Middle School, Norwalk, CT.
 

        Two 20 minute movies: “Greenland on the Hudson,” shows Hudson River glacial deposits and takes you back 18,000 years to view a variety of glacial settings which are still visible today; and “Scientist and Eemian,” how two scientists obtain climatic records from the Greenland ice sheet. These movies were part of a presentation at the 32nd International Geological Congress, Florence, Italy, Aug 2004

        Professor Yuri Gorokhovich, currently at Columbia U, presented two short movies which he produced, “Greenland on the Hudson” and “Scientist and Eemian,” on glaciers and the glacial periods. Inspired by the students’ apathy towards geography, Gorokhovich valiantly set out to bring enthusiasm to the classroom. His spectacular footage of the Greenland glaciers, filmed with a simple, handheld vidio-camera and edited on a PC, equaled professional photographers.

        “Greenland on the Hudson” gracefully connects present-day Bear Mountain of upstate New York to the hundreds of thousands years old glacier in Greenland. Glacial retreat of the last ice age, Wisconsin, shaped the topography of today. 120,000 years ago, the Northern Hemisphere was covered in a thick crust of ice. At the end of the Wisconsin glacial period 18,000 years ago, the ice began to melt. Gathering velocity as it flowed toward the basal part of the glaciers, the melt water eroded the land and formed valleys and rivers. The sediments, freed by the glacial melting, were separated along the way according to mass: first depositing the boulders, then the gravel and finally the fine sand and silt.
The shifting ice sheets, pulled by gravity, carved up the land and left behind polished rock surfaces and artic deserts with deposits of fluvial sediments. This seemingly lifeless terrain gradually transformed into the thriving ecosystem of today as the wind and water spread the fertile loess and silt, providing the basis for the vegetation which would later support animal life. The melting glaciers also provided the new and fragile ecosystem with its source of lakes and streams.
Today, there are still glaciers of the Wisconsin glacial period remaining in Greenland and Iceland. Moving up to 25 meters a day, these glaciers continue to replenish the ocean with fresh water to replace the water lost through evaporation and maintain a stable salt concentration in the ocean that is vital to the survival of aquatic organisms. This crucial role of the glaciers was credited as the movie concluded with spectacular scenes of the explosive force of glaciers as icebergs broke off, falling 50m and creating 20m tidal waves; a sure way to catch the attention of students.

        In the second movie “Scientist and Eemian,” Gorokhovich interviewed Professor Jorgon Peter Steffensen, Copenhagen University, regarding the study and extraction of ice cores. Since each year a new layer of snow and ice is added to the ice sheets, the ice is composed of 100,000s of layers of ice that reflect on the environment of each year. Therefore, ice cores have been used to learn about the climate history during previous ice ages in an attempt to track past climate trends for the purpose of predicting possible future changes in our climate.   The Eemian interglacial period, just before the Wisconsin glacial period, is of particular interest for it is believed to be similar to the present interglacial period we are living in. Scientists have discovered through the chemical properties of the ice cores that there was a high carbon dioxide level in the Eemian atmosphere along with two periods of extreme cold. Therefore, they want to determine the stability and progression of the Eemian climate to give an insight as to what may be the outcome of global warming today.
 
        The drilling of ice cores is done in tunnels in the glaciers, sheltered from the frequent, brutal snowstorms on the surface. The drill is a hollow tube with cutting blades attached that retrieved cylindrical cores of ice over three kilometers deep and 100,000s of years old. These ice cores are then processed and stored under -30°C ready for testing. However, the process of retrieving ice cores is not as easy as it seems, for further down, the pressure becomes so great that the ice turns into water with a temperature of 0-3°C. Therefore, many techniques had to be invented, including the addition of alcohol to the ice, to facilitate the drilling and to prevent ice cracking.   In the 1990s, two ice core drilling projects 30km apart from each other, the European GRIP and the American GISP, were funded in Greenland to extract ice cores. They aimed to create a detailed, year by year record of the climate for the past 120,000 years and, as a bonus, determine biological activity and molecules present then. The ice cores were tested for chemicals such as ammonium nitrate, hydrogen peroxide, formaldehyde, calcium and other biological compounds. The electrical conductivity of the ice cores were also tested to determine the pH of the ice layers, for changes from acidic to basic represented the changing of seasons with each acid-base pair equaling one year.   However, despite the accuracy of the ice core method of determining climate, the last 300m (110,000 years old ice) of the two drilling projects did not agree. As a result, a third drilling project was initiated to solve the discrepancy. This new project discovered that the theoretical basis for analyzing the ice core was flawed due to the fact that the ice did not age as much as expected as the drilling got deeper. It was thought that the thickness of each ice layer decreased exponentially further down, but in reality, it remained approximately 1cm thick throughout. This phenomenon was due to an unexpected heat flux that increased with the closeness to the underlying bedrock. Therefore, the bottom layer of ice was constantly being eaten away at a tremendous rate and eradicating the climate evidence of the earlier Eemian years.

With this new insight, scientists are reanalyzing the ice core results and are using them to predict future climatic changes and to advise people on how to best protect the environment. If it turns out that the Eemian period is indeed similar to present conditions, Scientists want to prepare people and prevent them from repeating the conditions that led to the sudden, extremely cold episodes of the Eemian. Judging from the enthusiastic response of the audience, Professor Yuri Gorokhovich has indeed succeeded in making geology interesting. Though this field may not be exceptionally lucrative, he has faith in the creation of more fun and educational films to spark interest in students, both children and adults alike. Professor Yuri Gorokhovich can be reached at <YG119@columbia.edu>

Myra Hauben won the Sargent-Welch $50 gift certificate door prize.

        An evening of non-stop demonstrations suitable for the science classroom by members of the Chemistry Teachers’ Club of New York and the Physics Teachers Club of New York.

        Al Delfiner showed a method for demonstrating Le Chatelier’s principle or any forward and reverse process that reaches equilibrium. Starting with two beakers of water, he used two glass tubes of different radii as pipettes to simultaneously transfer water back and forth from beaker to beaker. The larger tube held more water, but as the depth of the water in the beakers changed, the system approached equilibrium and the water levels eventually became constant. He said it was possible to calculate the exact ratio of water levels at equilibrium based on the ratio of the squares of the inside diameters of the tubes.
Najla Hallak presented a set of clocks created by her students with the numbers replaced with their corresponding elements from Hydrogen to Magnesium. The projects were all creative (one was actually a functioning radio) and showed a fun way to introduce students to the period table.

        Jay Rogoff, resident magician, showed us that alchemy wasn’t dead by transforming a cup of water to a pile of sand and pulling sand out of thin air, catching our attention for his next two demos. First was a sealed plastic container with a rubber glove diaphragm in which he mixed hydrochloric acid and ammonia. The acid and base neutralized, and he used the rubber glove to push out smoke rings from the resulting gas. The last demo was a plastic rocket filled with water and Alka-Seltzer to create a very satisfying pop and launch, which he showed can be easily made with film canister fuselages, Styrofoam fins, and expanding foam to create the nose-cone.
Peter L. Bastos presented some of his son’s favorite toys, starting with a spinning Spider-Man toy. The weight is unbalanced, creating a wobble in the toy as it spins. Next was a spinning light, which he suggested could be used to show sequence and circuits, as well as wavelength. Finally, an extremely popular object was the “Hovercopter,” a remote controlled flying saucer that was a simple fan inside a dome, showing Bernouli’s law.
John Roeder posed the question, “Is electricity free, and if so, why pay for it?” which he used to show the simplicity of solar cells. He showed that the LED in a disk drive is a simple solar cell in reverse: current applied to the diode emits light. By shining a light on it and measuring the voltage, we saw that a pocket flashlight on an LED can create a potential difference of 0.44V, and he said a 100W housebulb gave him a reading of 1.3V earlier.

        Joan Laredo Liddell was kind enough to furnish us with handouts, describing the demos she showed including the latest information from the American Chemical Society about National Chemistry Week for 2005. First she demonstrated polymer strength by having audience members partially inflate balloons and then inserting a skewer into the thick spot near the top, through the ballon, and out at the thick area near the neck without making it pop. Inserted from the side would pop it immediately. The other two demos she briefly described were the famous drinking bird (or dunking duck) to show vapor pressure, and making soap bubbles out of irregularly shaped wands to show that surface tension is always minimized in a sphere.

        Steve Gould also had a surface tension demonstration for us. His soap solution consisted of detergent, water, and glycerin to prevent evaporation. He sandwiched three thumbtacks in a triangle between two Lucite plates, immersed it in the detergent solution, and then put it on an overhead projector to show the films created. Three line segments converged from the tacks to a point inside the triangle, which is the Fermat point of the triangle, the point at which the line segments have the shortest lengths.

        Myra Hauben gave us a show of chemistry, dropping a copper penny (that means pre-1982) into a beaker of HNO3, with a hose leading to another beaker containing NaOH and phenolphthalein. The copper reacts with the nitric acid solution to create NO2, which bubbles through the hose and makes the phenolphthalein indicator turn clear from pink, showing the effect of acid rain neutralizing the basic solution. Once the copper runs out, the water backs up through the hose and turns the original beaker a brilliant sky blue.

        Joe Sencen had quite a few demos to show us. First off was the “Zero Blaster,” a simple toy gun that shoots out a fog ring. Next were spinning lights that create concentric circles, which he showed could represent energy levels of electrons. He had a set of LEDs in concentric circles that lit up in sequence when voltage was applied, hooked up to electrodes which he dipped in a tank of water. The pure water wasn’t conductive enough to light up the LEDs, nor was the solution created when he dumped in sugar or even salt at first. He suggested not stirring the salt to create an electrolytic solution, but instead letting it diffuse naturally and move the electrodes around to show the different levels of conductance at different depths over time. His last demonstration was a way of showing the different effective ranges of various indicators. Black boxes with distinctly colored LEDs were placed on a large sheet of metal (held on with magnets) and could be rolled back and forth, which triggered the LEDs to change at different points on the sheet of metal (spotted with clear packaging tape,) which was marked with a pH scale.

         Steve Zellman had an extremely long spring (which got as much envy as any of the fancier toys) which he handed one end to an unsuspecting audience member and after a quick warning not to let go, proceeded to send waves his way. Steve pointed out that when he sent an up pulse, he ended up receiving a down pulse, and then went on to create standing waves and show the nodes.

        Bob Capalbo had a rapid fire set of simple classroom demos, starting with two Styrofoam cups sandwiching a balloon. As the balloon was inflated, it pushed the air out of the cups and created a vacuum, so that the cups were stuck to the balloon: a simple one-way valve. Next he had a flexible straw on which he balanced a ping pong ball. He twisted his head side to side and the ball followed due to Bernoulli’s law, because as velocity increases pressure decreases, and the airflow on either side of the ball kept it balanced. He showed Bernoulli’s law again by holding up two sheets of paper and blowing between them, which produced the counter-intuitive result of making the sheets move towards each other. Taking off his belt, he balanced it on a hook on his finger, showing that the buckle fell naturally directly under his finger so that the downwards pressure on that point keeps it stable. Finally, he demonstrated an exercise in which students can balance a ruler on two fingers, close their eyes, and move their hands together with constant force (not velocity). Because the closer to the center their hands are, the greater the normal force and therefore the force of friction, both hands will meet at the center of the ruler no matter where they started from.

         Jack DePalma started off by making a kazoo out of a chewed up straw, then snipping the end off repeatedly to raise the pitch. After putting a strip of tinfoil under a horseshoe magnet, he ran a current through the foil which made it rise up, demonstrating the left hand rule for magnetic force on a current carrying conductor. He showed us UV beads, plastic beads that change color when exposed to UV radiation, and one audience member suggested coating them in sun block to test the various SPFs. He showed the Astroblaster, a set of rubber balls of decreasing size attached to a stick, with a small free ball held on top, which show transfer of momentum by sending the top ball shooting off when the entire system is dropped. He also had a Bunsen photometer to show us, which consists of two wax blocks sandwiching a sheet of foil. He attached a piezoelectric buzzer to a string and swung it around his head to illustrate the Doppler effect. Lastly, he pointed a TV remote control onto a photocell attached to a speaker, which generated different sounds depending on which button he pushed because the remote control works by sending differently pulsed infrared signals.

        John Rogosic, on break from MIT, came in with materials to demonstrate magnetic inductance. John dipped a copper ring into liquid nitrogen to chill it and lower its resistivity, and then placed the ring on a vertical Plexiglas tube. When he dropped a neodymium magnet into the tube, it came almost to a halt at the ring as the current induced in the ring from the changing magnetic flux caused a magnetic field opposing the original movement. He explained that if you had a copper ring with a small slit to break the circuit, you could show that without current, there would be no opposition. And as long as we had liquid nitrogen lying around, he let a test tube sit for a while, and when he removed it you could see liquid oxygen and argon ice. Helen Creedon provided the Dewar. She explained the Dewar flask, which has a groove etched in the styrofoam stopper to allow pressurized gas to escape, we were also told that that’s the reason the threads on soda bottles are discontinuous.

This month’s Sargent-Walsh $50 gift certificate door prize donated by regional sales manager David Garell went to Patricia Meehan of Robert Kennedy HS, Queens. Also raffled off were 15 Scientific American magazine awards for a year’s subscription. These were for a classroom teacher and 5 outstanding students. The subscriptions were donated by Marc Rosner, Scientific American consultant.
 

        The meeting started with short demos by Joe Sencen, Bob Drake. Then “E-Z Carry” demonstrated their foldable, washable, reusable, 100% plastic display boards. In addition to science fair projects and the like, the boards can substitute for erasable “white-boards” for those who are allergic to chalk dust. <EZCarryDisplay@hotmail.com>
Guest speaker Professor Monica Plisch of Cornell University’s Center for Nanoscale Systems introduced us to the world at the nanoscale. A nanometer is equal to10-9meter and is approximately the size of 3-5 atoms lying in a row! At the nanoscale (0.2-100nm), unique characteristics come into being: Surfaces and interface play a major role, van der Waals forces become stronger relative to gravity, quantum effects also become important and, with a greater surface area to volume ratio, new chemical properties develop. Finally, nanotechnology is a converging point for all the sciences overlap at the nanoscale.
The first great push for nanoscale research was from the physicist Richard Feynman, the “Godfather of Nano”. He was intrigued by the idea of being able to manipulate and control things on the small scale and made his classic talk, “There’s Plenty of Room at the Bottom!” in December, 1959. He foresaw the boundless possibilities in nanoscale research and proceeded to spur its growth by creating contests with monetary awards to anyone who can make ever smaller objects, such as a micromotor less than 1/64th of an inch on each side.

        Recently interest in nanoscale technology has bloomed, for only now have scientists developed the technology necessary to experiment at the nanoscale. Motivated by the electronics industry’s desire for breakthroughs in devices, circuits, computing methods and information processing, scientists of all fields have joined to develop new instruments and methods to further the nanoscale research which would benefit them all. Even the government has noticed the potential in nanoscale and, under President Clinton, introduced the National Nanotechnology Initiative (NNI) in 2000 which was followed up by President Bush’s request for an additional $982 million in funding this year.
To assist research at the nanoscale level, the scanning tunneling microscope (STM) and the atomic force microscope (AFM) were invented. The STM allows scientist to obtain atomic-scaled images of metallic surfaces. It has an impressively sharp tip (approaching one atom) which it uses to sweep over the sample’s surface. With a voltage applied to the needle, an electric tunneling current begins to flow between the tip of the needle and the sample when the tip is extremely close to the surface atoms of the sample. This current changes proportionally as the distance between the tip and the sample fluctuates. As a result, by keeping the current constant, and therefore the distance between the tip and sample constant, the topography of the surface can be recorded according to the up and down movements of the needle tip. The AFM works in a similar way except that it drags its needle tip on the surface of the sample and traces its topography by maintaining a constant force. The AFM is more versatile than the STM in that it can be used on non-conductive surfaces. It has also been used to determine the forces between atomic bonds and probe protein conformations.
Additionally, a device capable of weighing particles to the precision of an attogram (10 -18g) has been invented. It may have the possibility to detect viruses and other cellular components to the benefit of biology and medicine.
Nanoscale building blocks such as carbon nanotubes have also been discovered and manufactured. Carbon nanotubes are made of sheets of carbon atoms in hexagonal rings rolled into a tube. They have an enormous potential as they are the best thermal and electrical conductors and, relative to their size, are the strongest material due to their carbon-carbon bonds. Researchers are now experimenting with carbon nanotube transistors in hopes of creating nano-sized computer chips in the near future.  Nano fabrication methods have also become more standardized and the possibility of silicon oscillators is being tested. Should researchers succeed, cell phones can be made even smaller as the current macroscale quartz oscillators are replaced.

        As with any new invention, tests checking for possible detrimental effects of nano particles like carbon nanotubes have been preformed. Although these tests show negative effects for subjects who inhaled extremely high amounts of carbon nanotubes, it should be noted that nano particles have existed since ancient times and are widely found in nature. For example, certain bacteria contain nano-sized magnetite particles (Fe3O4) to help in navigation. Nano particles are also produced regularly in combustion reactions and are found in car exhaust.
 

                        Prof. Grier is the founding member of the NYU Physics Department’s new Center for Soft Matter. Refer to <http://physics.nyu.edu/grierlab/> with special attention to the section on holographic optical trapping, which he describes as “very visual material, and can be quite appealing to non-scientists.”

        This month, Professor David Grier of NYU Physics Department’s new Center for Soft Matter introduced us to his research on dynamic holographic optical trapping. In the late 1980s, a method was discovered to utilize light as tweezers to create optical traps for micrometer-sized particles. Since then, these particle-trapping optical tweezers have become indispensable tools in the physical studies of macromolecular and biological systems.
A simple optical tweezer consists of a single laser beam bought to a tight focus with a microscope objective lens. Since the area of lowest potential energy is located at the focus of the light, micro-particles will follow the momentum density and become trapped at the focus. This technique has revolutionized the study of DNA in biology. Scientists have attached strands of DNA to one micrometer wide plastic spheres which are easily trapped and manipulated by the optical tweezers. With the plastic balls suspended in water and trapped into place, the water flow rate is increased to create a drag on the connected DNA and stretch it out. By using the ratio of the drag on the DNA to the length the DNA is stretched, scientists can calculate the bending modulus of the DNA and find out how hard they should pull on a coiled DNA strand to decode it without knotting it up.
At the next level, these optical traps can be moved around in three-dimensions by changing the angle the laser beam enters the lens. Therefore, if multiple beams of light are shone through the lens with different angles of incidence, multiple traps can be created in space. However, having to shine multiple beams of light through the lens can be cumbersome. As a result, a method of splitting one beam of light into many beams traveling in different directions has been discovered. By utilizing the interference properties of light, a beam of light can be shone through a pattern of modulation of light (a.k.a. a hologram) that diffracts the single beam into many beams whose direction is pre-determined by computer calculations. With this technique, scientists can create multiple traps using a single laser beam that is limited only by the amount of funds available (1,000 traps can be made with 1 watt costing $10,000).
Now that multiple traps can be created, the next step is to move these traps in space. A LCD spatial light modulator is used to imprint a computer-designed phase modulation onto the laser beam as it passes through. The LCD is in grayscale and the thicker, darker areas translate into more phase delay. With the ability to move the traps around in three-dimension, isolated chemical experiments can be preformed on the microscopic level. Chemicals can be brought together using the optical tweezers and the increase in light intensity can initiate a chemical reaction between the substances.

         Although the reason behind it is currently unknown, even particles at the nanoscale can be trapped by the optical tweezers. The optical tweezers can trap and manipulate carbon nanotubes (6nm x 10um) to build structures out of them. Semiconductor nanowires can also be trapped and intense light can be used to weld wires together. This ability to manipulate objects at the micro and nanoscale creates unlimited amounts of possibilities. It opens the door to creating three-dimensional computing and much more compact devices. Microscopic turbines running on light radiation have been built through this technique and are used as mixers in cells or in experiments performed in microscopic environments.

        The ability to arrange particles has also been used to create quazicrystallines. These crystals have rotational symmetry but no translational symmetry, meaning that the crystal structure does not repeat itself (in theory, it is not actually a crystal since it has ten fold symmetry). The ability to create quazicrystals is important because they are semiconductors for light and can be made into light switches that works just like electrical switches found in computer chips. This creates the possibility that an optical computer will be made that is capable of relaying information at the speed of light!

        Additional methods of moving the traps have been discovered. One technique, called optical peristalsis, moves the particles in one direction by shifting the potential energy wells in a ratcheting movement so that the particles will come out of one energy well and roll down into the next. This method is similar to how dynein works in our cells by transporting materials along microtubules. Toroidal optical traps known as optical vortices were also created by giving the beam of light a helical wavefront. The perfect destructive interference that results causes the light to focus in a ring instead of at a point and the energy to exist in the form of orbital angular momentum that can be transfer to particles. Particles trapped in the optical vortex will move around in a circle as fast as 1000rpm. A second vortex spinning in the opposite direction can be placed inside the first vortex to create a microscopic gear pump. A 3x2 block of these pumps have been used to pump red blood cells and platelets in blood samples.

        As incredible as the current advancements in optical trappings are, there are still unlimited possibilities for the application of optical tweezers, and research in this field is bound to result in new discoveries and technologies that will impact the physical and biological world.
 

        Professor David Katz of Pima Community College is an accomplished chemist and chemical educator who has traveled the world to spread his enthusiasm for science and belief in hands on experiments. This month he presented to an audience of about 100 “The Joy of Toys in the Science Classroom” and revealed the chemical secrets behind many common toys. This was part of the ACS celebration of National Chemistry Week.
Professor Katz first showed us the super-shrink paper, a seemingly innocent sheet of overhead transparency until you bake it. In just four minutes, the 8 _” by 11” transparency will shrink to one-third its original size along with any writing or drawings on the sheet. This phenomenon occurs because super-shrink paper is a bio-oriented polystyrene film that has been extruded under stress, and heating it to 325°F reverses the process and causes the film to soften and shrink to its original pre-stressed size. (http://www.paper-paper.com or Flinn Scientific)

        Next, with the help of a troop of enthusiastic kids from the audience, Professor Katz demonstrated the applications and versatility of rubber. Rubber is composed of multiple strings of coiled polymers cross-linked together to form an elastometric network that uncoils or stretches when pulled. Professor Katz showed us a demo to illustrate the effects of cross-linking by making a solution of latex powder and water and then cross-linking the solution with the addition of vinegar. The watery latex solution immediately transformed into a solid rubber mass.

        Professor Katz also revealed to us the secrets of a magic trick in which he punctured balloons with a needle and a bamboo skewer without popping them. The trick was to puncture the balloons through the ends where the rubber was thickest so that the rubber would form a seal around the needle instead of ripping and bursting the balloon. An additional secret was to rub oil on the needle in order to help it slide.  Then he demonstrated how to make silly putty, a popular toy which arose from a failed attempt by General Electrics to make synthetic silicon rubber. Silly putty is a non-Newtonian fluid that dilates under stress. Therefore, silly putty will shatter or crack if it is hit by a hammer. Homemade silly putty is easily made by mixing Elmer’s Glue, baby powder, water, borax (a laundry aid found in supermarkets) and food coloring.   Although homemade silly putty is fun to make, Professor Katz recommends silly putty fans check out Crazy Aaron’s Putty World online where one can find magnetic silly putty and silly putty that change color. Magnetic silly putty has iron oxide added to it while silly putty that changes color due to heat has liquid crystals mixed in. Liquid crystals are cholesterol derivatives that shift positions due to pressure or temperature. The shifting affects light interference and therefore causes the color to change. A vial of liquid crystal can be purchased for $100 and can last for five to ten years of classroom use.

        Professor Katz also showed us his well-preserved, fifteen year old slime (another non-Newtonian fluid) and demonstrated how to make slime simply by mixing water, food coloring, guar gum, glycerin and borax solution.
Professor Katz then demonstrated a fun way to illustrate fluorescence and the photoelectric effect using a sheet of glow-in-the-dark paper. Glow-in-the-dark paper is made from phosphorescent zinc sulphide which causes the paper to have delayed florescence and slowly release the light energy it has absorbed. The photoelectric effect can be demonstrated by drawing on the paper with red, yellow, green, blue and UV penlights. Only the green, blue and UV light will have enough energy to excite the electrons of the sheet to cause it to fluoresce while no marks will appear on the sheet when drawn on with red and yellow lights.
Then, Professor Katz showed us the super ball and the stupid ball. The super ball is an amazing bouncer while the stupid ball simply plops to the ground and stays there. This extreme difference is mainly due to the form of polybutadiene used. Cis-polybutadiene makes up super balls and has 95% resilience due to the loose packing of the molecules. Stupid balls, on the other hand, are made of trans-polybutadiene which packs tighter and crystallizes.
Next, we saw the incredible absorbability of sodium polyacrylate, which is found in disposable diapers. These crystals can absorb water up to 600 times their weight. They were invented by the Department of Agriculture to help retain water in arid farmlands and are now modified by toymakers to create toys that grow when soaked in water.

        Professor Katz also revealed the magic behind disappearing ink and Hollywood Hair Barbie® Magic Hair Mist. The magic is based on the principles of acid-base indicators. Thymolphthalein and phenolphthalein are used respectively to produce the blue and pink colors. The indicators are dissolved in denatured ethyl alcohol with a few drops of NaOH to make the solution turn blue or pink. After the disappearing ink or hair spray is applied, the carbon dioxide in the air dissolves into the solution causing it to increase in acidity and turn the indicator colorless. Professor Katz demonstrated this reaction by putting a few drops of disappearing ink onto a cloth and exhaling on one stain providing more carbon dioxide which made the stain turn colorless quicker than the control stains.
As a conclusion, Professor Katz showed us Blaster Balls, a pair of ceramic balls coated with a mixture of potassium chlorate, sulfur and finely ground SiO2 which produces a bang when hit together. His final treasure was a thirty year old Big Bang Cannon® (http://www.bigbangcannons.com) fueled by water and calcium carbide. When fired, the vacuum created in the barrel causes a sonic boom ending Professor Katz’s spectacular presentation with a bang.
This month’s raffles were won by Carole Keil of P.S. 11 and Janet Kennedy of Fort Hamilton High School and everyone received a CD-ROM with all the recipes and science behind the demos.
 

        The story of underground coal fires in small town Centralia located in the middle of Pennsylvania State still attracts attention of scientists, media and general public. These fires burn for more than 40 years, starting in 1962 after local residents decided to burn an old landfill with a state permit. Since landfill was located in abandoned coal mine strip, coal picked up a fire and started going. As a result the town was announced an “eminent domain” and more than 1,000 residents were relocated. The town of Centralia became a ghost town. The story of Centralia is only one of many underground fires throughout the world.

        Dr. Yuri Gorokhorich, Lamont Doherty Laboratories, Columbia U, <yg119@columbia.edu>, presented his latest educational movie, Centralia to Remember. Inspired by the curiosity and passion of his geology students, Professor Gorokhorich set out to Pennsylvania to capture the history and effects of Centralia’s underground coal fire to bring back to the classroom.
Found all over the world, underground coal fires are relentlessly incinerating millions of tons of coal each year. The hundreds of coal fires throughout the United States, China, India, Ukraine, Russia, Australia and South Africa are a significant global issue. The hundreds of million tons of coal burned each year not only deplete our valuable coal resources, but they also release millions of tons of harmful gases into the atmosphere. The fires in China alone are estimated to consume 120 million tons of coal annually and produce 360 million tons of carbon dioxide. The carbon dioxide, carbon monoxide and sulfur dioxide produced by the combustion of coal are harmful to humans and hurt the environment by causing global warming and acid rain that damages plant and aquatic life.  The coal fires can be caused by natural ignition. Lightning strikes can ignite coal deposits and excessive sunlight with the right combination of oxygen can lead to spontaneous combustion. However, these fires are also commonly caused by human negligence. Fire codes and precautions often lax after coal mines are abandoned and nearby garbage burning may set fire to the remaining coal reserves. Setting fires to clear forests above ground for farming or building has also been known to ignite underground coal deposits.   Once started, these underground coal fires are difficult and costly to stop. The current options range from constructing barriers to contain the fire to totally excavating and extinguishing it. However, often times these options are too expensive and fires are left to burn themselves out which can take hundreds to thousands of years; the Burning Mountain Nature Reserve in Australia is estimated to have been burning for 5,500 years!

        In the movie, Centralia to Remember, Professor Gorokhorich tracks the story of the underground coal fire started in Centralia, PA,an old mining town. Through this movie, he explores how human negligence and selfishness caused many environmental disasters. Centralia’s underground coal fire started in 1962 by an authorized burning of garbage which ignited a mammoth underground coal vein. It is still burning presently and has spread to cover over 400 acres. Ironically, the fire could have been stopped before such irreversible damage was done when a resident offered to bulldoze the still small fire for $150. However, Centralia and its neighboring town disputed over who should pay the bill and, by the time Centralia accepted the responsibility, the fire was already too big and expensive for them to extinguish.

        The media quickly picked up the story of the “Town On Top of an Inferno” and the state government of Pennsylvania had to step in. For the next two decades, workers battled the fire, flushing the mines with water, excavating the burning material, backfilling, drilling again and again in an attempt to put out the fire or at least contain it. However, all their efforts failed and the drilling even helped the fire propagate by allowing in more oxygen to fuel the combustion. By the early 1980s the fire had affected about 200 acres and the cost to contain it was estimated to be $660 million.  With all hope and intention of extinguishing the fire gone, the government declared the town to be an “eminent domain” and set out to relocate the one thousand residents, providing them with $42 million in compensation. However, the fire and human greed continued to damage this community as residents split into violent factions over whether or not to relocate. In the end, the majority of residents left due to the generous government compensation. However, some parts of the town were unaffected by the fire and the residents refused to leave and give up their property. They claimed that the relocation was simply part of the government’s plan to exploit the situation and use the fire as an excuse to take over Centralia’s mineral rights to the underground coal which was estimated to range from three to tens of millions of tons.
Today, over 43 years and $40 million later, the fire still burns through old coal mines and veins under the town and the surrounding hillsides. The fire which ripped the town apart in the 1980s will burn for another century or more and could conceivably spread over 3,700 acres. However, during his visit, Professor Gorokhorich found the town and the environment already healing. The few families remaining have developed into a tight-knit, self-sufficient community whose greatest hope now is for the government to return the property rights so new residents can move in and restore the town to its old prosperity.

The door prize, a $50 gift certificate donated by David Garell, Regional Sales Manager, Sargent-Welch VWR International, was won by Peter Bastos of Hunter College.