ACS New York Section
High School Teachers Topical Discussion Group
2008 Annual Report
JANUARY 2008 MEETING
Dr. Stephen Gould, U.S. Environmental Protection Agency, <Gould.Stephen@epamail.epa.gov>,
“Introduction to Corrosion:
What it is, why it is of such concern, and some of the places it occurs in
everyday life.”
On January 11, 2008, Dr. Stephen Gould
<gould.stephen@epamail.epa.gov> spoke about types of corrosion associated
with iron, aluminum, and copper. By addressing problems corrosion can cause,
methods of prevention, and demonstrations that highlight aspects of the
corrosion process, Dr. Gould provided an observation-based approach to examining
corrosion and its influence in industry.
The term “corrosion” is derived from
the Latin corrodere, meaning “to gnaw away,” and NACE International defines
it as “the deterioration of a material, usually a metal, that results from
a reaction with the environment.” A metal may lose electrons and go into solution
as an ion, or, if no moisture is present, may share electrons with oxygen
or sulfur in its surrounding environment. Although often viewed as a gradual
process, in many cases it occurs rapidly: for example, when sodium is cut
it initially appears shiny, but a beige coating forms within seconds of exposure
to oxygen as the oxide forms.
To demonstrate the tarnishing (corrosion)
of silver, let a hard-boiled egg sit at room temperature overnight, remove
the shell, cut it in half, remove the yolk, place on a silver try, cut side
in contact with the silver, forming a dome. The dome traps the hydrogen
sulfide gas (a product of decay from the egg-white) forming silver sulfide
(silver tarnish). Because silver is less active than sodium, though, it
releases ions to a lesser extent in solution and takes longer to visibly
corrode—about an hour.
Probably the most common notion of corrosion
is rust, which proves not only a cosmetic problem but also an obstacle in
construction and gasoline storage. It caused the collapse of the Silver
Bridge along the Ohio River that led to 46 deaths, and underground gas tank
corrosion contaminated half the water supply in Santa Monica, CA. In fact,
a 2002 study by the Federal Highway Administration concluded that in the
U.S. corrosion costs owners of structures, manufacturers of products, and
suppliers $276 billion per year—three percent of the GDP.
Dr. Gould modeled a demonstration that
strikingly shows the early stages of rusting. A nail is placed in a hot
solution of gel (like agar or Knox gelatin) and pure NaCl. (Kosher, not
table salt; read the list of ingredients on the label.) When the solution
has cooled to room temperature, phenolphthalein in isopropyl alcohol and
potassium ferricyanide are added. This gel mixture is poured into a Petri
dish, and an iron nail is place in the dish. As rusting occurs, a blue precipitate
(Prussian blue pigment, potassium ferriferrocyanide) forms around the tip
and head of the nail where iron is oxidizing and going into the gel; and
phenolphthalein will turn bright pink elsewhere along the nail where excess
electrons reduce oxygen to form hydroxide ions. Corrosion begins at the tip
and head, the highly stressed parts, and the gel keeps the products of the
reaction separate.
A few methods of corrosion prevention
were also described. Metal can be coated with polyurethane or wax (as is
used in museums on armor), or an alloy can be used (as in weathering steel,
which forms a dense and adherent run that shields the underlying iron from
further corrosion). In fact, the Iron Pillar of Delhi has not rusted in 1600
years, possibly due to five times the customary phosphorous content; and
New York City manholes that contain two to four percent silicon or carbon
are shielded by products formed during and after casting that retard further
oxidation.
Additionally, a common preventative innovation
is cathodic protection, in which a more active, “sacrificial” metal serves
as an anode to resupply the “valuable” metal with electrons. The metals
must be bathed in an electrolyte, so cathodic protection is conveniently
used to protect underground tanks, pipelines and hulls of ships. A dramatic
demonstration for this principle is comparing corrosion of steel wool in
a 3% salt solution to corrosion when magnesium and steel wool are immersed
in a 3% salt solution—in the second case, steel wool remains unchanged as
the magnesium corrodes.
Unlike in iron, corrosion in aluminum
results in formation of a transparent, adherent protective aluminum oxide
coating that protects the underlying metal from further corrosion. However,
chloride can destroy this coating—if a drop of copper sulfate is placed on
aluminized Mylar, no visible corrosion occurs, but if salt crystals are added
to the copper sulfate, the Mylar quickly wears away. The specific mechanism
by which chloride attacks the aluminum oxide is still debated: chloride may
break bonds at the surface, it may penetrate gaps in the coating, or absorption
and ion displacement may lead to corrosion.
Of the eight major types of corrosion (uniform
corrosion, galvanic corrosion, crevice corrosion, pitting corrosion, intergranular
corrosion, selective leaching (dealloying), erosion corrosion, and stress
corrosion cracking), crevice corrosion is most associated with aluminum.
It commonly occurs in aluminum screws as threads corrode due to restricted
flow of corrosion products and difference in the environment and electrolyte
concentrations inside and outside the screw crevices. This can be especially
problematic because it results in loose screws, thus posing a safety hazard.
The final metal Dr. Gould discussed was
copper, which forms an attractive light-green patina when it corrodes. The
most widely known example of this is the Statue of Liberty—although people
were wary when it began turning green, it is now difficult to imagine the
statue any other way. The color change took twenty years, but now formulations
used by artists and architects can shorten the time required for patination;
and environmental factors also contribute to speed. For instance, patination
occurs more slowly in Hawaii than in other parts of the world because it
is inhibited by sulfur in volcanoes; and if a copper bar is repeatedly rubbed,
a patina will not form.
Because of pitting corrosion in copper pipes,
many homeowners have experienced frustrating pinhole leaks. Ironically,
these may have been the result in part of EPA attempts to reduce lead and
turbidity, leading to subtle changes in water chemistry. One focus of current
research is how to prevent corrosion in pipes used to transport ethanol.
It is also essential to explore corrosion-resistant materials for storing
nuclear waste and for selecting building materials, and increased experimentation
and understanding will enable this type of exploration in the future.
Chem Club Vice President Lew Malchick announced that the American Chemical
Society is seeking volunteers for the weekend of May 17-18 to perform demos
and foster discussion among participants in its Mid-Atlantic Regional Meeting
(MARM) at Queensborough Community College. The Sunday program will be similar
to the Chem Club’s annual “demo derby.” Those interested in presenting can
find more information by visiting <www.marmacs.org> and by contacting
Lew <bt_quant@yahoo.com>.
FEBRUARY 2008 MEETING
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.
Chem Club President Lew Malchick also announced
a few upcoming events that are open to anyone interested: the Science Council
of New York City is looking for volunteers to present on April 12 at Stuyvasent
High School; the American Chemical Society seeks volunteers to present at
a forum (similar to the Chem Club “demo durby”) that it will host on Sunday,
May 18 at Queensborough Community College; and a meeting to be held at Columbia
U Faculty House on February 26 will feature an AMNH associate curator discussing
the chemistry of meteorites. Elections for the Chemistry Club board will
be held in March, and the Chemistry and Physics Clubs are searching for a
reasonably-priced, handicapped-accessible location for the annual awards dinner
and welcome suggestions. In addition, UFT Science committee listserv users
are encouraged to post anything of interest to the scientific community, like
resources or questions.
MARCH 2008 MEETING
Dr. Julie Nucci, Director of Education Programs, Cornell Center
for Nanoscale Systems,<jn28@cornell.edu>, “Getting a Charge out of Light.”
At the March 14 meeting, Dr. Julie Nucci from
the Cornell University Center for Nanoscale Systems, <jn28@cornell.edu>,
delivered a presentation entitled “Getting a Charge out of Light: the Physics
of Solar Cells.” This discussion of energy needs, solar energy supply, the
physics of solar cells, and first, second, and third generation solar technology
served as a comprehensive explanation of the working and possible uses of
photovoltaic cells.
Dr. Nucci began by stressing the motivation
for developing solar cells: not only does reliance on fossil fuels for energy
increase carbon dioxide emissions associated with global warming, but it
also shows a lack of sophistication—why burn organic material for energy
when astounding advancements in fields like microelectronics, informational
technology, space exploration, biotechnology, and nanotechnology open revolutionary
possibilities? Humans’ instantaneous yearly averaged consumption rate is
13 TW (1012watts), and assuming a world population of nine billion and energy
conservation, by 2050 annual energy consumption is projected to reach 30
TW; but solar energy could potentially capture around 600 TW at any time.
When compared with the mere two to four TW extractable energy that can be
obtained from wind power, less than two TW power from ocean currents, and
five to seven TW from biomass if all cultivable land were used, this figure
shows the vast potential of solar technology to supply global energy needs.
Solar energy can be divided into three
categories: solar electric, which converts solar energy into electricity
using the photovoltaic effect; solar heat, which uses a concentrator dish
to achieve high temperatures or to split water molecules for H2; and solar
fuel, which uses specialized cells to convert light into biofuels. The opportunity
each of these three areas provides can be expressed as availability divided
by current usage, and since photovoltaic energy is extremely available but
only currently constitutes .015% of the world’s energy supply, it is the
most opportune.
The main obstacle inhibiting widespread
use of this technology is its high cost of implementation due to the amounts
of hardware required: over $0.30 per kW/h. Growth rate of global PV production
is approximately 30% per year, and every time production doubles, it becomes
20% less expensive, but the current rate of growth will not serve global
needs by 2050. Researchers are therefore seeking a fundamental change in
the current technology to lower costs and improve efficiency.
To introduce solar physics, Dr. Nucci used
a mechanical analog in which a ball rolls down a hill that represents potential
energy, and a “bubble” (or anti-ball) is propelled up the hill. Because
an absence of electrons moves towards an area of higher energy, a charge
separation occurs and produces voltage. In other words, when solar radiation
interacts with matter, the atoms absorb photons and electrons can jump the
gap to the conduction band.
The voltage of a solar cell depends on the
position of two bands. In semiconductors, silicon being the one most commonly
used in solar cells, there is a small gap between the bands. The size of the
gap decreases when the semiconductor is heated and its molecules move more
quickly, which explains why semiconductors are better conductors at high
temperatures. In the solar cell, a current is produced when electrons flow
from the positively charged band to the negatively charged one. In intrinsic
silicon, 1.1 electron volts are required to propel an electron to the opposite
band.
However, silicon’s valence of four makes it
a poor conductor unless doping is performed—impurities like phosphorus (the
n-type) and boron (the p-type) are added to the crystal. Phosphorous’ valence
of five provides extra electrons, and boron’s valence of three creates holes
that can be filled by flowing electrons. If the p-type and n-type are joined,
an LED results—the chemical potential (Fermi level) must equilibrate, band
bending occurs as a voltage gradient forms, carriers and holes move, and
light is emitted. This is like a solar cell running in reverse.
The voltage produced depends on the gap
between bands, and also on the doping used. A famous analysis by Schockley
and Queisser in 1961 attempted to determine efficiency in the solar cell
assuming a single p-n junction, one electron hole per incoming proton, the
thermal relaxation of electron-hole pairs, and illumination with unconcentrated
sunlight. With these conditions, 30% efficiency is theoretically possible.
Dr. Nucci also discussed three generations
of solar design. In the first generation, silicon is used because the semiconductor
industry can easily make it, but it is expensive and ranges from 6% to 41%
efficiency. The second generation includes organic cells like dye-sensitized
(mimicking photosynthesis), small molecule, and polymer solar cells; but
the drawback of these is that they degrade. The third generation is a new
approach and includes tandem cells and hot carrier cells, which are not yet
mastered—the fundamental obstacles is that the energy being tapped degrades
in 1014 of a second—but the idea of using quantum dots is also a new possibility.
Although there is still much to be done in
solar cell research, the developments Dr. Nucci described show the bright
future of the field. Recommended sources for additional reading included Peter
Wvertel’s Physics of Solar Cells, Jenny Nelson’s Physics of Solar Cells,
and Antonio Luque Steven Hegedus’ Handbook of Photovoltaics.
APRIL 2008 MEETING
“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.
The April meeting is the annual “Demo Derby” featuring easy-to-do
demonstrations with minimum equipment by members of the Chemistry Teachers’
Club of New York and the Physics Teachers Club. The demonstrators in
order of appearance were: Rudy Jones, Joan Laredo-Liddell, Judith Exler,
Bob Capalbo, Myra Hauben, Jean Delfiner, Fred Newman, Mike Spalding, Steve
Gould, Al Delfiner, and Jack DePalma.
SEPTEMBER 2008 MEETING
Gail Horowitz, Dept. of Chemistry, Yeshiva University, <ghorowit@yu.edu>,
212-960-5400 x6863, “Using the Digital Resources
of the Journal of Chemical Education.”
The invited speaker, Gail Horowitz, was unable
to attend the September meeting to present on “Using the Digital Resources
of the Journal of Chemical Education,” so the evening was spent discussing
a variety of academic resources available to chemistry and physics teachers.
Joan Laredo-Liddell, Al Delfiner, Jean Delfiner, Chris Ward, and Bob Cabalbo
led the dialogue by recommending science-related events, print resources,
demonstrations, and videos. Louis Pataki provided his laptop with NYU wireless
access to the Internet.
Mrs. Laredo-Liddell showed the two awards
that the American Chemical Society’s New York Section (ACS NYS) received
at the ACS Aug 2008 convention in Philadelphia for the work the NYS did
in 2007 when she was section chair. For teachers interested in forming a
Chemistry Club at their HS, the ACS offers a thick 3-ring binder with suggestions
and resources. It is free for the asking. Check ACS.org on the Internet.
The ACS NYS Brooklyn Subsection and St. Joseph’s
College, Brooklyn, invites student researchers to enter their 14th Annual
High School Poster Session on October 19 to present their work and to compete
for one of four cash prizes. More information can be obtained at the college
website <www.sjcny.edu/page.php/prmID/251> or email <JRehmann@sjcny.edu.
The New York Hall of Science, Flushing, NY,
the ACS NYS and the Pepsi-Cola Company are again cosponsoring student run
demonstrations for National Chemistry Week at the museum on Oct. 25. If
you and your students want to participate, contact David Sherman at <David.Sherman@pepsi.com>.
Free parking and free admission for workers.
Mrs. Laredo-Liddell suggested some publications
that teachers should consider purchasing for personal and classroom use.
A class set of Chem Matters, an ACS magazine published 4 times a year for
HS students, and National Chemistry Week materials can be ordered through
the ACS. Two intriguing books, “The Science of Chocolate” by Stephen T. Beckett.
RSC Publishing – UK, ISBN: 978-0-85404-970-7 and “Molecules of Murder: Criminal
Molecules and Classic Cases” by John Emsley, RSC Publishing – UK, ISBN:
978-0-85404-965-3, can be found on Amazon.com.
Teachers who seek access to the Journal of
Chemical Education without paying high fees to become a full ACS member can
alternatively pay $40 to become a member of the Division of Chemical Education,
which permits access to part of the JCE. “The Chemical Adventures of Sherlock
Holmes” by Thomas Waddell & Thomas Rybolt, is a compilation of articles
that appeared in the Journal of Chemical Education (1989 - 2004) is a volume
containing stories that serve as a fun way to teach concepts like stoichiometry—it
can be purchased through JCE.
Mrs. Laredo-Liddell raffled off a year’s subscription
to JCE. It was won by Bibiana Almache, Bronx Health Sciences High School
Mrs. Delfiner presented another important publication: the revised NYC
K-12 Science Safety Manual, which came out in June 2008. Principals are responsible
for ensuring that teachers abide by the manual’s guidelines, and students
and parents should also sign an included contract. Although the manual is
a lengthy, 135 pages, it is divided into chemistry, physics, Earth science,
and biology sections, so teachers can focus on the section pertaining to
their subject. A PDF version of the manual is available on-line. (See next
article: Required Reading ... .)
Mrs. Laredo-Liddell and Mr. Cabalbo also introduced
a few quick demos. Mrs. Laredo-Liddell showed that the Hoberman “Switch
Pitch,” a plastic ball that switches colors when tossed (interactive demo
at www.hoberman.com/fold/Switchpitch/switchpitch.htm). It is a great way
to visually explain concepts like activation energy and isomers. Another
highlight was Mr. Cabalbo’s demo of surface tension. He replaced the metal
seal on a Mason jar (available at most houseware stores) with a piece of
window screen and then filled the jar with water through the screen. When
he inverted the filled jar; some air entered and a little water leaked out
and then stopped. Ambient air pressure plus surface tension on the screen
balanced the pressure of the mass of water plus the reduced air pressure
in the jar. Tipping the jar allows air to enter and water to leave. Straighten
the jar so that water again covers the screen and the leaking stops.
Mr. Ward generated a discussion when he raised
the issue of developing effective practical sections for chem and physics
Regents exams.
Lewis Malchick found it and Mr. Delfiner showed a
website run by the University of Nottingham called “Periodic Videos” (www.periodicvideos.com).
This gem of a site contains short (1-4 minute) video clips for each element
on the periodic table. The segments include properties, demos and amusing
comments. They are updated regularly.
OCTOBER 2008 MEETING
Christopher Ward, Hommocks School, Mamaroneck, NY 10543, <Ward@mamkschools.org>,
“Using Video Interactively in the Classroom.”
Chris Ward < Ward@mamkschools.org >and
WNET employee Toni Scheflin <schetli@thirteen.org> presented the educational
resources that are available to teachers via < http://vital.thirteen.org
>, a website sponsored by WNET and WLIW21 networks (more commonly known
as Channel 13 and Channel 21). These resources include short video clips
demonstrating scientific concepts, interactive flash media, standards guidelines,
and lesson plans to accompany the media.
Mr. Ward and Ms. Scheflin focused primarily
on use of the site’s video resources. The typical length of a segment is
three to five minutes, as the educational developers chose the most informative
sections of longer videos. For each video, there are also corresponding
“Questions for Discussion,” NY State and National Science Education “Standards,”
and “Background Essay” tabs that can help teachers structure lessons using
the videos. These features enable teachers to use video within the context
of a traditional, discussion-based lesson.
The site also allows teachers to create
a “group” and to share “folders” of favorite links to videos and notes with
any other teacher who joins that group. Teachers can also create a group
with a folder of media, create a second account to give their students, and
have students access the media from home. (Use the “Save to a Folder” option
after navigating to the page of a useful segment.)
Mr. Ward has created a group for Chem Club members, which includes links
to four “high-impact” videos in each of four subject areas: biology, chemistry,
Earth science, and physics. It can be accessed by selecting “My Groups”‡
“Join A Group” and inputting the Group ID Number, 3878, into the search box.
Mr. Ward demonstrated possible ways to
use the site’s content as a springboard for classroom discussion. He stressed
that one key benefit to showing short segments is that you can pause the
video at any point to emphasize target questions and ideas. You can also
play a video without sound and have a student narrate. These practices keep
the viewing interactive and help keep students focused on the targeted concepts.
Mr. Ward concluded by summarizing major
components of putting these videos to use via his recommended method. Teacher
preparation includes considering learning objectives, considering resources,
previewing the segments, selecting “pause points” and “focus questions,”
and planning post-viewing activities. To prepare students, teachers should
ask thought provoking questions, prepare kids for segmented viewing, discuss
major points covered in the clip, present relevant vocabulary, and list key
concepts. The discussion should impress upon students that they are responsible
for extracting information from the video.
Ms. Scheflin said that Thirteen will
host a professional development conference on the “celebration of teaching
and learning” on Friday, March 6 and Saturday, March 7, 2009. There is a
small fee for participation in the conference, and more information can
be accessed at <www.thirteencelebraton.org>.
NOVEMBER 2008 MEETING
David Maiullo, Physics Support Specialist, Department of Physics
and Astronomy, Rutgers the State University of NJ, 136 Frelinghuysen Road,
Piscataway, NJ 08854, <Maiullo@physics.rutgers.edu>, 732-445-3872,
“Physics Demonstrations as Theater.”
David Maiullo, Physics Support Specialist,
Rutgers University, presented a series of nearly 40 physics demonstrations.
The presentation included both simple classics and less commonly seen demos.
Mr. Maiullo began by discussing certain
techniques for making demonstrations effective and exciting teaching tools.
For example, he stressed the importance of finding out the limitations and
available resources of the facility in which the demos will be performed
(gas, water, electricity, sight lines, lighting possibilities, etc.). He
also noted a few crucial do’s and don’ts for giving a demo show: do’s included
using familiar devices, incorporating audience participation, and changing
only one parameter during each demo, and don’ts included rushing, repeating
failing demos, and being esoteric.
Ten particularly dramatic demonstrations were the following:
Table Cloth and Dishes – Dishes, a water-filled vase, and a candle were
placed on a table that had been covered with a smooth, hem-less tablecloth.
The cloth was then quickly yanked downward (to keep the force horizontal),
but because of the inertia of the objects on the table, they remained almost
perfectly in place.
Fire Extinguisher Cart - Conservation of momentum
– Mr. Maiullo sat on a four-wheeled cart with a large CO2 fire extinguisher.
When he discharged the fire extinguisher, he, the cart and the extinguisher
were propelled in the direction opposite the stream of effluent.
Greek Waiter’s Tray - Water in glass swung in a circle –
A wine glass filled with water was placed in the center of a tray, which
was suspended by three cables. The tray was swung in a full circle over Mr.
Maiullo’s head, but because of the centrifugal force, the glass remained
on the tray, and no water was spilled.
Density: Diet vs. Classic Coke – A can of Diet Coke and
a can of Classic Coke were placed in a tank of water. The Diet Coke floated—small
air pocket in can. In contrast, the Classic Coke sank due—same air pocket
but corn syrup more dense than water.. When Mr. Maiullo added salt to the
tank, the density of the solution increased, so both cans floated.
Pressure of Atmosphere – A 55-gallon drum was evacuated
using a vacuum pump, and it imploded with a dramatic, loud sound.
Fluid in Motion – A cylindrical garbage can had rubber stretched
over one end, and a large hole cut out of the bottom. The can was filled
with smoke with a commercial fog machine (atomized glycerin sprayed over a
heating element) and held horizontally. When the rubber membrane was then
struck , a ring of smoke was sent from the opening on the other end to the
back of the room. The propelling force could be felt.
Flame Tube – A metal tube approximately 10 cm in diameter
and 1.5 m long, with one end sealed by a loud speaker and the other end
attached to a propane tank, and with a row of small holes along its length,
was used to visually demonstrate sound waves. The tube was filled with propane,
the gas escaping from the small holes was lit and the flame height adjusted
to 2 cm. When the speaker emitted sound, a standing wave was established,
and the height of the flames varied, correlating with the sound pressure
at that point in the tube, enabling the audience to visualize a sound wave.
When the frequency of the sound was increased, there were visibly a greater
number of nodes and peaks.
Breaking Glass with Sound – A glass beaker was placed in
a protective chamber and subjected to a variable frequency sound. When the
sound frequency matched the beaker’s resonant frequency, the beaker shattered.
Magnet in Tube – Mr. Maiullo demonstrated eddy currents
by dropping a small but very strong magnet into an open-ended thick walled
copper tube. As eddy currents slowed the magnet’s downward motion, it appeared
to “float” through the tube.
Bed of Nails – In a grand finale, Mr. Maiullo laid down
on a beds of nails and placed a second bed of nails on his chest. He then
had an audience member stand on top of the second bed. Because there were
enough nails on the bed, the total force was distributed so that the force
applied each nail was too small to do any harm.
Two resource sites for demo ideas, PIRA and the TAP-L listserv, can be
accessed at:
<http://physicslearning.colorado.edu/PiraHome/Resources.htm>
and <http://www.eskimo.com/~billb/>, respectively. Mr. Maiullo also
encouraged audience members to email him with further questions about any
of the demos performed; his address is Maiullo@physics.rutgers.edu. Finally,
he mentioned that Rutgers 10th Anniversary Faraday Christmas Children’s Lectures
will be given at the Rutgers Physics Lecture Hall, 136 Frelinghuysen Road,
Piscataway, NJ at 7:00 PM on December 12, 13, and 14.
DECEMBER 2008 MEETING
Dr. Jin Kim Montclair, Assistant Professor, Polytechnic University,
Brooklyn, NY, <jmontcla@poly.edu>, “Bio Related
Polymers.”
Jin Kim Montclare, Assistant Professor,
Polytechnic University, presented her lab’s research on bio-related polymers.
The first part of this research aims to artificially engineer catalysts that
could degrade plastic waste, and the second part involves designing artificial
proteins for therapeutic use. The two projects could potentially ameliorate
the problems of limited petroleum feed stocks and lack of “environmentally
benign” solutions to waste accumulation.
The study focuses on the group of biocatylists
known as cutinases, which fungal plant pathogens excrete in order to burrow
holes in leaves. The most commonly researched type is F. solani cutinase
(FsC), a compound used in industry to modify fabrics. However, Dr. Montclair’s
team seeks to expand the range of cutinases used for research and has focused
on aspergillus oryzae cutinase (AoC), which has been used in Japan to ferment
tsaki and tofu. The amino acid sequences of the two types of cutinases are
50% similar.
The team sought to identify the crystalline structure and to test the function
of AoC in order to better understand its potential uses in industry and
bioengineering. To examine the AoC’s secondary structure, the team compared
its disulfide bonds, surface charge distribution, and hydrophobic surface
distribution with those of FsC. Computer imaging revealed that AoC has one
additional disulfide bond, but the active sites of the two proteins had the
same stereostructure; so they can catalyze the same types of reactions.
AoC also was found to have a slightly different area and charge distribution,
and a more hydrophobic active site.
To compare the functions of AoC an FsC, the
team investigated rates of enzyme activity for PNP substrates using each catalyst.
(These substrates were used because their decomposition is easy to monitor—solutions
turn a yellow color.) It found that FsC prefers the p-nitrophenyl acetate
(PNPA) substrate to p-nitrophenyl butyrate (PNPB) or p-nitrophenyl heptanoate
(PNPH), while Aoc works fastest on PNPB and PNPH.
The team also conducted a thermoactivity comparison,
incubating the catalysts at a number of temperatures, comparing the heat
capacities of the enzymes, and seeing what happened when the enzymes were
denatured by heating and subsequently cooled. It found that AoC was more
thermostable, that there was no difference in the two enzymes’ heat capacities,
and that after being denatured, AoC can more effectively return to its original
structure than FsC can.
In the second part of the research, Dr.
Montclare’s team used its knowledge of nature’s polymers (polysaccharides,
proteins, and nucleic acids) to experiment with controlling a compound’s
chain length, sequence, and stereochemistry in order to construct a new polymer.
Unlike conventional polymers, protein polymers are not necessarily one monomer
repeated multiple times; they can be comprised of a discrete set of monomers
repeated multiple times. So the team experimented with arranging alpha helices
(obtained from the cartilage oligomeric matrix protein, COMP) and beta spirals
(obtained from elastin) to determine whether the orientation of the blocks
and the number of blocks influence the self-assembly and structure of the
constructed proteins.
The methods for this part of the study
included cloning a protein using restriction enzymes, purifying the proteins,
incubating the proteins with Vitamin D, and mutating the amino acids into
alanine to note the mutation’s effects on the secondary and tertiary structure
of the enzymes. By using dynamic light scattering of the elastin monomer,
the team compared the characteristics of proteins formed from Elastin-COMP,
COMP-Elastin, and Elastin-COMP-Elastin blocks and found that the orientation
of the fusion made a difference in the enzymes’ behaviors.
The team is currently collaborating with the NYU Dental School to explore
ways that the synthesized proteins could be used in tissues. Since they
bind to Vitamin D, it is possible that they could be used to facilitate
bone generation.
Prior to Dr. Montclare’s presentation,
Christine Constantinople, a PhD candidate at Columbia University, announced
that she is working with graduate students who are available to host a number
of workshops in schools. Topics include discussions on bioethical problems
in research; a “reverse science fair” in which students “judge” learning
stations put on by university undergraduates, graduate students, post-docs,
and faculty; and brain awareness days on which human brains, animal brains,
and a spinal cord are brought to elementary and high schools for a hands-on
exploration of the nervous system. For more information, email Ms. Constantinople
at <cmc2229@columbia.edu>.
Submitted by: Jean Delfiner, Co-chair
High School Teachers Topical Group
207 Lincoln Place
Eastchester, NY 10709-2005
914-961-8882/FAX 914-771-6669
JADelfiner@verizon.net
Date: November 29, 2008
