submitted by
Jean Delfiner, Co-chair 2009/2010
  Joan Laredo Liddell, Co-chair 2009/2010


Dr. Jerry DeMenna, Fun-Science Academics, 345 W. 58th St. Suite 2K, New York, NY 10019, 732-207-8835, <jerry@FUN-SCI.com>, “Learn That Technology Is Fun: Spectrometric Examination of Barbeque Sauce.”
Dr. Jerry DeMenna of Fun-Science Academics spoke to us on “Chemically Correct Cooking.” This was a broadening of his original title, “Spectrometric Examination of Barbecue Sauce,” because, as he said, he wanted to include some “other things.” Cooking, after all, he went on, is chemistry with organic reagents, including such processes as pH adjustments, neutralizations, esterifications, and dehydrations. Proteins, carbohydrates, and fats are the raw materials. There are only four tastes (sweet, sour, bitter, and salt), he said, but there are billions of flavors and aromas.
Analytical tools to evaluate cooking include spectroscopy, chromatography, thermometry, and electrochemistry. The infrared spectrum identifies fat, protein, carbohydrates, and water in food. While spectroscopy looks at whole samples, chromatography is based on separation of a sample ? gas chromatography found 88 peaks in olive oil in about 240 minutes and is used to measure cholesterol in foods for Nutrition Facts labels on food. (But many Nutrition Facts are still measured by outmoded methods, DeMenna added, some of these at the behest of food lobbies.) Electrochemistry identifies ions, also acidity and ionic strength.
But, in spite of DeMenna’s broadened title, the “main course” of his talk was still barbecue. He described barbecue from three regions of the country known for its distinctive barbecue. Barbecue from the Carolinas is based on pork and is made with an acidic marinade. Texas-style barbecue is based on beef, using sauce that contains sugar. Barbecue from Tennessee is based on all types of meat and uses dry rub.
The sweetness of Texas-style barbecue sauce, DeMenna said, was developed for improperly aged beef, to mask the sour “gamey” taste. (Beef is aged at 42oF. A higher temperature would accelerate the aging process but also increase the likelihood of spoilage.) Sugar also reacts with proteins and provides an alkaline environment to produce glycerin, which contributes to “juiciness”.
Acids in sauce for Carolina-style barbecue neutralize amines formed by the hydrolysis which decomposes proteins, DeMenna continued. They also sequester cholesterols and mono- and diglycerides to form safer triglycerides and esters. The same effect is achieved by applying lemon juice to fish. These reactions require sufficient time to produce their desired effect, he added, noting that four to eight hours are optimum for food flavor “development.”
When DeMenna applied chemical analytical methods to determine the composition of the acid barbecue sauce, sugar barbecue sauce, and dry rub, he found that the Texas sauce rated highest in taste but that the Carolina sauce was healthier because of its lower cholesterol and fat content.
The “other things” that DeMenna shared with us were french fries. Here the contrast was between McDonalds’ and Jimmy’s from the Jersey Shore. No significant differences were found in infrared and ultraviolet spectra, but the McDonald fries gave a doublet fluorescence peak versus a singlet peak from Jimmy’s. DeMenna observed that the only doublet he knew of came from _-benzo-pyrene, which is found in cigarette smoke. The major difference that he found was in the sodium chloride content, higher in the Jersey Shore french fries, which he attributed to salt in the air near the ocean, which reacted with the frying oil to form a small amount of organic sodium salts, which are, in effect, soap. Lew Malchick picked up on this to wonder why there was a similar difference between fries at Nathan’s at Coney Island and those sold “inland.”
Dr. David W. Hogg, Associate Professor, Center for Cosmology and Particle Physics, Dept. of Physics, NYU <david.hogg@nyu.edu>, “Massive Data Sets in Astrophysics Including Sloan Digital Sky Survey.”
Dr. David W. Hogg was unable to speak at the February 8 meeting due to illness, so Dr. John Roeder led an activity called “Jumping on the Moon,” part of an Active Physics course that is appropriate for all levels. The objective was to determine how high a person could jump on the Moon based on the height they can jump on Earth, and the discussion that ensued generated unique problem solving approaches.
The National Academy of Sciences promotes the idea that students’ prior experiences enable their future learning, so Dr. Roeder recommended speculating about the question at hand before obtaining experimental data. The key fact to remember is that the Moon’s gravitational force is one-sixth that of Earth. Common conjecture was that on the Moon, the average person could jump to six times the height they reach on earth.
However, examining the scenario more closely exposed another layer of the problem. When a person jumps, he first crouches the “ready distance,” reaching the “ready” position. He then extends his legs again, reaching the “launch” position. Finally, he travels the “peak distance” and reaches the highest point in his trajectory, the “peak” position. Regardless of the gravitational pull of his surroundings, his leg muscles will exert a relatively constant amount of energy each time he jumps. On Earth, much of that energy is used in order to overcome his gravitational mass and as he moves from the “ready” position to the “launch” position. In contrast, the Moon has a weaker gravitational pull, so not as much of the energy he exerts must be used to overcome inertia, and more of it can be converted to the kinetic energy that propels him the peak distance. As a result, a person on the Moon actually jumps more than six times the height of his jump on Earth.
This concept can also be described using formulas that enable students to calculate the height of their jumps on the Moon based on their jump heights on Earth: The work done by a jumper equals the increase in his gravitational potential energy, which can be expressed as Mass x the gravitational field of the planet x (peak distance ? ready distance). Because the work done is the same on the Moon and on Earth, the expression using Earth’s gravitational field can be equated to the expression using the Moon’s:
Mass x gravitational field of Earth x (peak distance on Earth - ready distance) = Mass x gravitational field of Moon x (peak distance on Moon - ready distance).
Mass and ready distance are the same on Earth and the Moon, and the ratio of Earth’s gravitational field to the Moon’s is 6:1, so dividing by the Moon’s gravitational field generates the useful form of the equation: 6 x (peak distance on Earth - ready distance) = peak distance on Moon - ready distance.
Dr Roeder directed participants in taking measurements of their own jump heights (using a measuring tape and masking tape markers; all measurements are from the floor to the jumpers waist, the presumed center of mass) to gain a full understanding of this formula’s use. A more familiar example of the principle being investigated is a swimmer’s ability to jump higher in a pool than on land. Once students understand this concept, they can explore other aspects of the Active Physics program; for example, the program incorporates a “challenge” to introduce topics, like the task of inventing a game that can be played on the moon. Related discussions that might arise include the difference between falling motion on Earth and on the moon, the way the moon’s gravitational conditions can be simulated on Earth to test the game’s effectiveness, and the process by which one can plot and compare trajectories on the Earth and the Moon.
Dr. William Horak, Chair, Energy Sciences and Technology Department, Building 475B, Brookhaven National Laboratory, Upton, NY 11973-5000, 631-344-2627, <horak@bnl.gov>, “Integrated Planning for Energy Security and Environmental Sustainability.”
Compared to other countries in the world, the U.S. is relatively energy independent. This is because 80 percent of our energy comes from North America, while most Saudi oil goes to Europe. Our sense of energy dependence comes from our shortfall in transportation, which is 97% dependent on oil, as opposed to only 70% in Europe.
This is how William Horak, Chair of the Energy Science and Technology Department of Brookhaven National Laboratory, opened his presentation on “Energy and the Environment: Pathways to a Low Carbon Infrastructure” on 13 March. And our awareness of our shortfall in transportation sparked our interest in everything he had to say. Horak structured his presentation in the context of what he called the Energy Trifecta: 1) the American Recovery and Reinvestment Act of 2009 (aka “Stimulus Bill”), 2) the Energy Policy Act of 2009, and 3) the Climate Change and Recovery Act of 2009. The “Grand Challenge,” he said, was to increase energy supply while decreasing carbon intensity.
Horak cited three approaches to reduced carbon intensity: 1) Socolow and Pacala’s “wedges” from their 2006 article in Science; 2) a report from EPRI (Electric Power Research Institute) in 2007; and 3) McKinsey’s Reducing US Greenhouse Gas Emissions: How Much at What Cost?(2007). He categorized Socolow and Pacala’s 15 “wedges” as follows: end-user efficiency and conservation (3); power generation (2); carbon capture and sequestration (CCS) (3); alternative energy (5); and agriculture and forestry (2). He also displayed a bar graph from the McKinsey report showing cost on the vertical axis plotted against the number of gigatons of carbon that would be eliminated per year, starting with negative bars representing savings from conservation measures and then positive bars representing costs for alternative energy sources. Horak observed that, because the savings from the negative bars pretty much equaled the costs from the positive bars, the issue of dealing with climate change is not economic but rather choosing how to do it. He added, though, that the amount of savings was conditioned on the degree to which the measures which lead to savings could penetrate the market.
There are many energy-environment assessment tools, Horak said, ranging from simple spreadsheet models to sophisticated human factors (semi-delphic) models. Brookhaven uses MARKAL (for MARKet ALlocation), with a reference energy systems, calibrated to the National Energy Modeling System (NEMS), with a wells-to-wheel approach, detailed technology models, and market penetration based on least cost (though he cautioned that people sometimes make economic decisions for reasons other than least cost). MARKAL does energy policy analyses to answer “what if” questions. It gives answers for reaching specified goals but does not provide a roadmap to the future. One of the applications of MARKAL concerned carbon prices for a variety of technology sets, with “business as usual” technology set as a base. Horak showed a graph of cost per ton of carbon dioxide removed versus the amount of carbon dioxide to be eliminated. The graph started at the origin and increased in a concave upward shape, rising to $100/ton carbon dioxide at the targeted amount of carbon dioxide to achieve a stabilized average global temperature. He then displayed the effect of adding in seven different carbon dioxide reducing measures (including IGCC (integrated gas combined cycle) with CCS, nuclear, geothermal, solar, and wind). Each lowers the curve and moves the point at which the cost of carbon dioxide removal becomes positive over to the amount of carbon dioxide it can remove. Horak observed that carbon dioxide emissions credits were recently auctioned for $3/ton carbon dioxide.
Other studies with MARKAL have investigated the potential impact of hydrogen fuel production, the effect of the Global Nuclear Energy Partnership program (with the nuclear power base decreasing in 2030 as old plants are decommissioned and not replaced), and whether it would be better to trade with Brazil for ethanol rather than produce it with locally-grown corn (probably not, given that Brazil is likely to increase its use to all it can make).
Regarding the “Energy Trifecta,” Horak outlined the financial provisions of the “Stimulus Bill”: $38.7 billion to the US Department of Energy (DOE), including $11.3 billion for grants to states and municipalities for energy efficiency projects; $2 billion for advanced batteries, $4.5 billion for a “smart [electric power] grid”; $3.4 billion for CCS; $6 billion for loan guarantees, and $4.5 billion for research and development (with $0.4 billion for ARPA-E (to develop novel innovations related to energy as DARPA does for the Department of Defense), $0.7 billion for biofuels, and $0.4 billion for geothermal).  Horak noted that since McKinsey is a consultant for DOE, the Stimulus Bill priorities match the mid-range abatement curve in his report.
The second part of the Trifecta is the Energy Policy Act of 2009. Horak expected it to contain proposals from Representatives Waxman and Markey, with an energy efficiency portfolio standard and a renewable energy portfolio standard. Horak suggested that combining these two into a combined standard would yield improved results.
For the third member of the Trifecta, the Climate Change and Recovery Act of 2009, Horak recommended a carbon dioxide emissions tax rather than the cap-and-trade which has successfully reduced sulfur dioxide emissions from power plants. Except in the electricity sector, carbon dioxide emissions cannot be localized (as sulfur dioxide can), and the difficulty of tracking carbon dioxide emissions from their source means that it is more equitable for users to pay according to the total amount of carbon dioxide generated in producing the products they use.
“Demo Derby,” an evening of non-stop demonstrations (5-8 minutes max.) If you want to participate, just bring your demo, clean-up equipment and safety apparel. Write your name on the board. Remember, its quick, quick, quick. You’re not teaching, just showing what can be demonstrated in the classroom.
Al Delfiner: Mass the Gas—Mr. Delfiner took an empty plastic soda bottle with a tire valve inserted into a 3/8” hole in its cap, and pressurized the bottle with a bicycle pump. The bottle pressure was measured with a tire pressure gage. Having purchased a digital scale for only $8 < saveonscales.com > (which he highly recommended), Mr. Delfiner compared the mass of the pressurized apparatus with the mass after the cap had been opened and the pressure returned to ambient. Using the measured change in mass, the gage pressure, and the stated volume of the bottle, he calculated the density of the pressurized air. When converted to STP conditions, the measured density was within 5% of the published desity.
Bob Capalbo: Center of Gravity—Mr. Capalbo stood two rulers on edge in a v-shaped formation, placing a book beneath the open end of the “v” to prop that end up. He placed across the lower end of this “v” two funnels he had taped together at their mouths. Contrary to intuition, the funnel assembly rolled uphill, to the propped-up end of the “v,” although the center of gravity was in fact moving downward.
Instant Rust—steel wool was added to a mixture of vinegar, water, and bleach. The Cl+1 rendered the bleach unstable, so the steel wool rusted in a matter of seconds.
Myra Hauben: Mostly with Soda Cans…--Ms. Hauben had stripped the outer layer of paint off of aluminum soda cans by placing them into 18M sulfuric acid. She had also exposed the plastic liner by suspending the exposed aluminum in a 6M NaOH solution (in a fume hood). This process shows how quickly NaOH reacts with aluminum. All that was left was the plastic liner.
Plus, these cans can be used for a dramatic demo:  Use an awl or a file to scratch a ring in the plastic on the inside of a soda can. Then, pour in a 0.5M copper (II) chloride solution to cover the scratch. After five minutes, you can pour out the solution and rip the can easily. (Must wear goggles and thick protective gloves.) Only the paint on the outside is holding the can together.
Lew Malchick: Videos of Superheated Steam—Although Mr. Malchick was not able to be present at the meeting, his videos showed the use of an apparatus spewing superheated steam. The invisible steam was hot enough to char paper and to light a match. A stainless steel temperature sensor, a thermocouple, and Vernier Logger Pro had been used to prepare and record the heating curve.
Jack DePalma: Slinky in Wood Frame—if a flag is placed on a slinky connected to a wooden frame and the slinky is rotated, even though it looks like the slinky moves forward, the flag remains in the same horizontal position.
Motorized car—This toy has traction such that it can climb up a vertical surface, flip over, and proceed to travel upside-down.
Kofi Donnelly: Screencasts of Demos—Mr. Donnely explained how screencasts can be used to make videos of demos and instructions, which can then be posted to YouTube for students to re-watch at their own leisure. He showed some examples: a step-by-step explanation of how to use excel, a screencast of waves colliding, a screencast showing how ticker tape measures velocity, and a screencast illustrating inertia. He recommended software called “iShowU,” which costs about $20 and which can be used in conjunction with a digital camera to create the screencasts.
Steve Gould: Intervening Dominoes—Mr. Gould showed how one small block of wood can be used to knock over a huge one by creating a domino line of wood blocks that gradually increase in size (and potential energy).
Viewing Infrared—Our naked eyes can’t see the infrared rays that a TV remote emits to signal the cable box; but a digital camera can. Simply view the infrared output through the lens of a digital camera, and the rays are vivid.
Joan Liddell: The Floating Golf Ball—When a golf ball is placed into a graduated cylinder containing two or three inches of kosher salt to which water has been carefully added (so as not to disperse the salt), the golf ball sinks. However, as the salt dissolves over time, the golf ball gradually rises due to increase in the liquid’s density. Ms. Liddell suggested leaving the setup in the classroom over a period of time; in her experience, students rushed in excitedly to check the progress of the ball on its upward path.
John Roeder: Wobbling Bulls-Eye—This gadget is an asymmetrical, egg-shaped block of wood that has a large bulls-eye painted onto each side—on one side, at the block’s center of mass, and on the other, off-centered. If the wood is spun and flung in a horizontal or vertical trajectory, the bulls-eye appears to wobble on the latter side. But on the former side, it appears stable.
John Shea, CEO, Division of School Facilities, NYC DOE Division of School Facilities,44-36 Vernon Boulevard, Long Island City, NY 11101, < JShea3@schools.nyc.gov>, “Sustainability Initiatives of the NYC DOE.”
Is it possible to imagine a future in which every school in New York City is energy efficient?  John Shea, <JShea3@schools.nyc.gov>, CEO of the division of school facilities (DSF), has that vision. On September 25th, he spoke about the department of education’s initiatives to create a more sustainable school system.
The DSF has undertaken the difficult task of improving the energy efficiency of New York City’s public schools. According to Mr. Shea, its mission is to “provide a safe, comfortable, and clean setting that is conducive to the education and nurturing of our students in the most economic and efficient manner possible.” Although these responsibilities are great, they come with ample resources. As New York City’s largest government agency, the DSF oversees 1,200 buildings and 1,882 employees.
Mr. Shea outlined the DSF’s method for creating more sustainable schools. First, schools’ staff and students must understand their local responsibilities to respond to a global challenge. Without the positive mindset of an enthusiastic community, it is difficult to make a school more environmentally sound. The DSF will create a program to improve each individual school, providing for a sustainable future. Finally, students must be taught about the importance of the DSF’s efforts and how they can help.
Mr. Shea believes that the most important support comes from children. He thinks that students, at 1.1 million strong in New York City, are more instrumental to fashioning sustainable schools than both the state and national governments. A sustainable school must engage the whole community, with students and staff learning about improving sustainability and working together to reach that goal. By sharing knowledge with the younger generations, tomorrow’s environmentally aware citizens are born.
The department of education’s sustainability committee organizes the improvement of schools’ environments. It is divided into four sections: recycling, technical, educational, and communications.
The recycling division mandates that every school in the department of education system have a sustainability coordinator on the teaching staff to monitor the school’s success at improving its environment. Each school must also file its own recycling plan. These plans are unique to every school as they are all in different situations. Finally, this division fosters student participation in the effort to increase recycling in schools.
The technical division handles projects, software, and innovations that help schools become more sustainable. Green roofs and renewable energy sources, such as solar and wind power, are being investigated for use in schools by the technical division. The effect of these installations would be twofold: not only would they reduce energy waste, but students could see their positive effects. The technical division also provides some schools with the EPA’s portfolio manager. This software takes all of a building’s energy data and gives its user a comparison to other buildings and tools to manipulate the data. Most importantly, it generates a benchmark for schools, so that the following year they can aim for better results. This also allows both staff and students to monitor energy consumption, giving them more incentive to participate. Some innovations already installed by the technical division in several schools include energy saving light bulbs and motion detectors that turn off lights when classrooms are not in use.
Student and faculty awareness of environmental issues is handled by the educational division. This division persuades schools to teach about, or at least mention, protection of the environment in all possible subjects. K-12 schools now often have sustainability in their mission statements. The educational division also engages in staff development, instructing teachers on ways to make their schools environmentally sound and on how to interest students in sustainability.
What is the attainability of this mythic sustainability? It is still uncertain whether the department of education will ever be able to make all its schools environmentally sound. However, it is predictable that this feat will take a lot of hard work. Even though its goal is monumental, all the effort the DSF is pouring into this project gives hope that someday every school in New York City will be energy efficient.
Prof. Mark M. Green, Polytechnic Institute of NYU, Dept. of Biological and Chemical Science, 6 Metrotech Center, Bklyn, NY, <mgreen@duke.poly.edu>, “Backwards Learning Applied to Chemistry.”
Joe Sencen opened the meeting with a short demo; “Cloud in a Bottle.” He covered the bottom of a 2 liter soda bottle with tap water approximately 5 cm deep and then dropped in a smoking match. He then used a one hole rubber stopper connected to a tire pump to moderately pressurize the bottle. When Joe released the pressure, a cloud formed. When he repressurized the bottle the bottle, the cloud disappeared.
In the academic study of the arts, the principles necessary to create a work of art such as a painting or a poem or a musical composition are discovered by studying the completed work. In this way the student encounters the beauty arising from the use of these principles at the very beginning, with the pleasure of this encounter stimulating the desire to understand what stands behind such an accomplishment. The method of learning of the arts is close to how we learn outside of the academic world, how a child learns from the start. We don’t learn the alphabet before we hear people speaking. We don’t learn the colors or the shapes of common objects before seeing the world around us. The wonders of sound and shape and color intrigue us and stimulate our desire to figure out what is going on and what it all means.
The guest speaker, Prof. Mark M. Green, Polytechnic Institute of NYU, Dept. of Biological and Chemical Science, <mgreen@duke.poly.edu>, wrote this in the preface of Learning the Fundamentals of Organic Chemistry Backwards: A Story Telling Historical Approach, the organic chem textbook he is writing.. This approach, he pointed out, has two points of emphasis: 1) to show the full complexity of the systems to be studied at the outset, and 2) to explain the historical evolution of our present understanding. For his first example to illustrate this approach, Green began with the first chapter of his book, “From Cellulose and Starch to the Principles of Structures and Stereochemistry.” He starts out with diagrams of starch and cellulose in abbreviated notation, something he said is usually not gotten to until page 950 in a conventional organic chemistry textbook. He then uses this as a basis for teaching about molecular structure, tetrahedral bonding of carbon, isomers, and the experimental basis for understanding these topics. He showed a slide of 17 chemists and explained how each contributed to our present understanding of structures in organic chemistry.
Green went on to say that his second chapter, “From Galactosemia to the Properties of Six-Membered Rings - An Introduction to the Mechanisms of Chemical Reactions”  continues the theme of structure, this time within the context of galactosemia, a disease whereby galactose from lactose in mother’s milk poisons infants. For the historical basis of this understanding, another 11 chemists were cited. Next he pointed out that his third chapter , “Carbocations: From the Synthesis of High Octane Gasoline to the in Vivo Production of Terpenes” , recounts improvements in the structure of gasoline which helped the British against the Germans in the Battle of Britain (higher octane, more power, faster plane.) Here he cited the contributions of 16 more contributing chemists and pointed out that the chemistry involved here is the same as that by which the body makes cholesterol and, thence, sex hormones.
Chapter 4,  “Aromatics: a Word That Came to Mean Something Other Than Odor in the Chemical Sciences” , recounts Faraday’s determination of the formula of benzene and Kekulé’s determination of the structure of benzene. Here Green cited 14 more scientists responsible for the historical development, one of them, H_ckel, who was not promoted because he was a physicist working on chemistry. Chapter 5, “Catabolism, Anabolism, Metabolism, Carbanions and Carbonyl Chemistry: Fatty Acids, Glucose, and the Citric Acid Cycle”,  discusses the structure of fats and their metabolism, also the Krebs cycle, and 15 more chemists are cited. The last chapter he has written so far  “A Great Deal Can Be Learned About Organic Chemistry From the Study of Polymers and the Monomers from Which They are Made”  starts with the discovery of polyethylene. The chemistry of branching which follows, Green said, is the same as that for making birth control pills. He cited the work of 12 chemists in the historical evolution of the chemistry of this chapter. He added that he has two more chapters to write - on “Classic Synthesis” and “Elastomers.”
In closing, Green recounted the change in the teaching of organic chemistry when Morrison and Boyd first published their seminal text on the subject, which introduced mechanisms along with the descriptive chemistry which had previously been the mainstay of the subject. He feels that the teaching of organic chemistry is now at a point of needing another new approach, and he hopes that his will be the one. He noted that veterans of his course at Polytechnic reported back to him that they had an easier time in taking their MCATs.
Jay L. Rogoff <JLRogoff@hotmail.com> and Chris W. Ward <MagicBug@verizon.net>, “Magic to Grab Your Student’s Attention.”
Jay Rogoff and Chris Ward showed that they are not only excellent science teachers but also extraordinary magicians. Rogoff started things off by giving us an impression that we were going to see a chemistry demonstration by lighting a torch. But in just an instant he corrected any misimpressions we might have had. Rogoff transformed his torch into a wand and proclaimed that it would, indeed, be an evening of magic.
Ward then came in to describe what he called the psychology of magic; it also might be considered rules of etiquette among magicians, and he asked us to abide by them as well:
1) Don’t perform at another performer’s event.
2) Don’t give away secrets by telling or giving a bad performance.
3) Don’t touch another magician’s equipment.
If you want to become a magician, Ward said, get a mentor and both he and Rogoff offered their services (their e-mails are <MagicBug@verizon.net> (Ward) and <JLRogoff@hotmail.com>). And if you use magic to teach science, he added, have your students deconstruct the trick rather than give it away.
In more of the vein of psychology of magic, Ward pointed out that magicians can get you not to see one thing by asking you to focus on something else, and he illustrated this by showing the by now familiar video of people, half dressed in white, half in black, passing basketballs. By asking us to count the number of passes among the players dressed in white, he was able to keep us from noticing the gorilla that entered and left the scene.
Rogoff then showed some magic based on chemistry, by claiming to transform the ancient elements of air and water into earth. He also transformed some water into air, with the aid of sodium polyacrylate, and he demonstrated that a cousin of sodium polyacrylate reacts with water to make fake snow.
Next it was the trick of writing one’s initials on a sugar cube with a pencil, then placing the sugar cube in water (Rogoff said any liquid would work) and placing one’s hand over the container, only to find the initials reappearing on one’s hand. Rogoff presented this in the context of nonpolar solutes not dissolving in polar solvents, with water being polar and graphite (carbon from the pencil) being nonpolar.
After that came rope tricks, which Rogoff found to be analogous to single, double, and triple bonds; and, when Rogoff transformed the three ropes of unequal length to three ropes of equal length, he called it “hybridization.” This he followed with a rope and ring trick and a coin and Coke bottle trick. Rogoff’s final tricks illustrated electromagnetism: He had a volunteer charge his hand by rubbing it so that it could raise a dollar bill in his other hand, and he showed that a suspended dollar bill was attracted to a neodymium magnet ? he said that the ink contains enough iron to do this.
In addition to closing with some card tricks, Ward also shared a few tricks of the trade. One is called the “French drop,” in which the magician pretends to place an object in his left hand with his right hand and holds up his left hand to distract observers while dropping the object (still in his right hand) into his pocket, then being able to show the disappearance of the object. Ward also pointed out that picking up chalk to write on the board allows for easy switching between “happy” and “sad” balls to illustrate how a “happy” ball made good on its guarantee of a million bounces but not a single one more. He then showed us the website he had created for us to learn about the techniques he had employed, by setting up a magic group on VITAL, the video resource on the Internet he had presented to us in his last appearance. The directions he supplied were very straightforward: Go on the web to <www.thirteen.org>, and click on “Education,” then on “Video Resources” to get the VITAL page. After completing the registration procedure, click on “My Groups” and sign up for group 5862. There you will find recommended You Tube videos, with annotations provided by Ward.
Julie Nucci, Ph.D., Director of Education Programs, Center for Nanoscale Systems (CNS), CNS Institute for Physics Teachers (CIPT), 632 Clark Hall, Cornell University, Ithaca, NY 14853, <jn28@cornell.edu>, “The Physics of Metals.”
Joe Sencen introduced a novel fashion of teaching students how to balance equations. By using physical representations of the reactants and the products in any equation, students are able to visualize the reaction, and therefore can more easily balance equations. The example equation Sencen used was that of silver nitrate reacting with copper to form pure silver and copper (II) nitrate. Under the names of these molecules, written on magnets so as to stay fixed to the chalkboard, were placed the physical representations of each reactant and product. Once the students understand that two nitrates are needed in the product to balance out the +2 charge of the copper product, it is simple for them to comprehend that another nitrate is needed on the reactant side, solely by balancing the equation visually. Adding another nitrate to the reactant side, however, necessitates another silver to be added to the same side, to keep the same amount of silver and nitrate molecules in the silver nitrate. Once again, the student is able to see clearly that there are two silver molecules on the reactant side, while only one on the product side. Therefore, one more silver molecule must be added to the product side. The equation has now been balanced.
This month’s speaker, Dr. Julie Nucci, <jn28@cornell.edu>, was then introduced. As the director of education programs at the Center for Nanoscale Systems at Cornell University, she runs the Center’s Institute for Physics Teachers, which, among other responsibilities, entails organizing outreach to improve physics education, developing lab activities, and presenting new and interesting physics topics for teachers.
At Rensselaer Polytechnic Institute as an undergraduate, Dr. Nucci realized that many biomedical engineering students were not getting work upon graduating, and therefore she changed her major to another interest of hers, material science., the “Mettle of Metals,” stemmed from this area of research.
While the study of characteristics of and bonding within and between metals is a physics based approach to the analysis of metals, the study of defects in metals is the focus of material science. After briefly explaining some characteristics and bonding properties of metals, Dr. Nucci spoke of the importance of defects in metals.
Characteristics of metals include high electrical conductivity, high thermal conductivity, ductility, malleability, strength, opaqueness, and shininess. In addition, almost all metals are solids at room temperature, and can be alloyed with other metals.
The free electrons in a metal can propagate freely; in other words, they have constant kinetic energy. All electron energy values are allowed for these mobile sub-atomic particles. The wavelike properties of these electrons are proportional to their velocity and momentum.
There are two basic structures of materials. In a crystalline structure, the ions are arranged in a periodic order, which is very structured, compact, and strict. In an amorphous structure, however, the ions are located at random positions. The most basic crystalline structure is that of a simple cube, in which ions are organized as if they were on all the vertices. More common than this structure are the body centered cubic and face centered cubic structures. The most ductile materials are face centered, meaning their ions are located as if they were on the vertices of a cube and in the center of each face of that cube. By contrast, the body centered cubic materials organize their ions again as if in a cube structure with ions at each of the vertices, but instead of having ions on all the faces, one ion is located in the center of the cube.
The lattice structure comes about by ions naturally staying in the space where they are most stable. When ions are close together, they are repulsed away from each other; when they are far apart, however, columbic attraction pulls them together. The ions are most stable at the place where the columbic attraction is equal to the repulsion. At lower temperatures, the ions will move closer together. The opposite is true for high temperatures.
In metals, there are bands of energy levels where electrons may reside. The filled valence band contains bound outer shell electrons. The band just at a higher energy level than this is in fact very close to the valence band, even slightly overlapping the valence band, and is always available as a place to go for high energy electrons. When energy enters a system, metals, as conductors, are able to transfer this energy, as their electrons are able to easily jump up energy levels. In addition, these close energy bands are the reason metals are opaque. When an optical photon hits metal, it is taken in by the material, which absorbs the light. Therefore, metals are opaque rather than clear. These properties are exactly the opposite of those of insulators, which have a great distance between their valence band and empty, higher energy, band. In semiconductors, these two bands are closer together than in insulators, but not as close as in conductors.
Electrons are usually moving quickly between collisions, however their net motion is negligible, as the random collisions keep them in generally the same place. However, when heat enters a system, the electrons in the area with the most heat will begin moving faster, and therefore will diffuse toward a colder spot. Similarly, electrons conduct electricity by drifting in response to an applied voltage.
Metals can have defects which affect their various properties. One dimensional defects in part determine the mechanical properties of metals. In an edge dislocation, a line of lattice is incomplete. In a screw dislocation, a chunk of lattice is pushed over to one side, and therefore is not directly facing what it theoretically should.
Blacksmiths are an example of people managing dislocations. By first heating the metal, it is softened because it takes away defects. Then the metal is hammered, which puts back in defects, making it hard once more. The addition of these dislocations to metal make the metal stronger.
The following is an example of the strength resulting from defects in metal. If a rod of metal is bent, then with the same or similar force, that piece of metal cannot pushed back into its straight form, because the defects acquired from the bending make the metal stronger.
Many metals have very small grains, or pockets, which are separated by a boundary from the rest of the material. Like other defects, these grains make metals stronger. Aluminum connections in computers chips were made in long, thin strands. As electrical current passed downstream, electro migration, or the electrical current biased diffusion of atoms, occurred in aluminum. Bits of aluminum were pushed forward, resulting in the failure of many computer chips. This has been fixed by using aluminum with grains, so that the electrical current can travel through them, instead of having to push aluminum.