Akron Phy sics Club
Meeting Announcement: MONDAY, January 26, 2004 - TANGIER, 6:00 PM
With a change of pace appropriate for the first meeting of the New Year, we will welcome Dr. Robert Brown, Institute Professor, Department of Physics, Case Western Reserve University. Prof. Brown will be speaking about
THE NOBLE AND NOBEL MRI:
A Simple View of it, and Its Increasingly
Rich View of Us and Our Brain
Minutes, January 26, 2004
Minutes not available.
Meeting Announcement: MONDAY, February 23, 2004 - TANGIER, 6:00 PM
Our February speaker is R. Byron Pipes, Goodyear-Appointed Endowed Professor of Polymer Engineering, the University of Akron, who served as Distinguished Visiting Scholar at the College of William and Mary during 1999-2001, where he pursued research at the NASA Langley Research Center in the field of carbon nanotechnology. So, appropriately, the title of Dr. Pipes' talk is:
van der Waals Interaction Forces:
Evidence of their Power in Single Wall
Carbon Nanotube Arrays
Minutes, February 23, 2004
Gathered to hear our speaker despite the cold, gloomy February weather were Georg Böhm, Dave Brown, Alper Buldum, Dan Galehouse, Jack Gieck, Bob Hirst, Ben Hu, Leon Marker, Robert Mallik, Jerry Potts, Darrell Reneker, Boyd Simmons, Jack Strang, Ernst von Meerwall, Joe Walter, and Charlie Wilson – plus first-timers Ted and David Varga. Welcome aboard, gentlemen!
In an incredibly brief business meeting, Treasurer Dan Galehouse advised that our wealth had increased $3.00 since last month, resulting in a new balance of $81.38, which is $2.00 less than we had in November – demonstrating that under Dan’s professional fiscal management, he has achieved his objective of preserving the steady-state stability of our miniscule treasury (which is preserved in a portable metal box to limit evaporative losses). [Neither the reader nor the writer will be required to diagram that sentence.]
At which point, Chairman Ernst von Meerwall introduced our speaker, Dr. R. Byron Pipes, Goodyear Tire & Rubber Professor of Polymer Engineering, the University of Akron, who, Ernst explained, is also in charge of the University’s Akron Global Polymer Academy. A mechanical engineer, Dr. Pipes’ returned to the world of academe at the University of Akron after serving as dean, provost, and president of other universities.
Our speaker’s subject was van der Waals Interaction Forces: Evidence of their Power in Single Wall Carbon Nanotube Arrays. Noting that all engineers were [and are] originally applied physicists [an orientation with which this writer enthusiastically agrees], Dr. Pipes said that he approached single-wall nanotube arrays as an engineering material. “Things happen at that scale that we simply don’t understand,” he declared, “and the properties of materials change with scale.” So he took on the task (for NASA) of studying how the properties of carbon nanotubes change as their scale is changed.
He explained that scaling up a carbon atom into a material that can be used in an airplane requires going through fourteen orders of magnitude: starting with a carbon atom, making that into a carbon nanotube, building the result into an array, twisting the arrays into a nano-wire, building these wires into a micro-fiber, and collimating those micro-fibers to produce laminated layers that can be used in airplane. “How do we get from the intrinsic properties to something as complex in geometry as that?” Dr. Pipes reviewed highlights of his calculations, showing us some of the steps that enabled him to come up with answers to that question.
Carbon nanotubes, it seems, are “born” (from a gaseous phase, growing on suspended catalyst particles at high temperatures) as single-walled graphine nanotubes. These can be anywhere from a single nanometer in diameter to 6, 8, or 10; and multi-wall concentric tubes can go as high as 300 nanometers. Each layer is an almost perfect hexagonal array (we were treated to a Power Point electron microscope image, since the hexagons are too small to be resolved by light waves). Although their stiffness decreases with diameter size, Dr. Pipes’ calculations (supplemented by physical data) have revealed that at nanotube scale, ordinarily negligible van der Waals forces become so powerful that when laid together with their sides touching one another in a parallel array, the bonding of these fibers is twice as great as epoxy bonding! Their separation averages 0.318 nanometers. This is not due to chemical bonding but to van der Waals forces.
The “sphere of action” of these attractive forces between molecules is reported (in my 1939 physics text) as ten thousandths of a millimeter. But a nanometer is a millionth of a millimeter – well within this “sphere of action,” providing some insight into the scale we are dealing with in nanotechnology.
Twisting hundreds of nanotubes together [as the textile industry does with cotton or wool], and then twisting hundreds of the resulting arrays together, then repeating the process until one has a seven-element array yields a fiber containing a trillion nanotubes that is one fourth the diameter of a human hair. This fiber, our speaker found, has four to five times the shear strength of conventional polymers – which promises to make a very light but highly effective reinforcement for continuous-phase polymer layers.
Dr. Pipes likens the effect of the van der Waals attraction to putting nails into a bridge made out of two boards, one on top of the other. Without the nails the boards slide over one another as the bridge bends. But nailing them together, preventing any sliding movement between them, adds greatly to the elastic modulus – the bending moment or strength of the bridge. The above seven-element array offers 76% of “unity,” or perfect bonding.
During the question and answer period, our speaker made a comment that seemed to indicate his satisfaction with having switched from administration to an environment in which “new knowledge is being generated.”
“To me what’s exciting about research,” he said, “is going out there and finding something that no one else has ever seen. To me it’s just intoxicating.”
WE WELCOME VISITORS!
Meeting Announcement: MONDAY, March 29, 2004 - TANGIER, 6:00 PM
Our March speaker is Clyde Simpson, who is in charge of the Cleveland Museum of Natural History's Ralph Mueller Observatory, and its 10 1/2-in refractor telescope. In addition to the observatory's educational function, he does daily solar monitoring for the Solar Section of the American Association of Star Observers. Mr. Simpson's subject is:
Astronomy at the Cleveland Museum of Natural History
Minutes, March 29, 2004
Gathered to hear our speaker despite the threatening March bluster were Dave Brown, Tom Brooker, Sam Fielding-Russell, Milian France, Dan Galehouse, Jack Gieck, Bill Jenkin, John Kirszenberg, Leon Marker, Jerry Potts, Darrell Reneker, Jack Strang, Ernst von Meerwall, and Charlie Wilson.
In a delightfully short business meeting, Treasurer Dan Galehouse advised that our wealth had decreased $1.00 since last month, resulting in a new balance of $80.38 – a constant that through his financial sagacity, our treasurer has managed to maintain within ± 1% for months!
Program Chairman John Kirszenberg outlined the next meeting’s program on 26 April, which will be a talk by University of Akron’s Professor of Polymer Engineering, Erol Sancaktar, who will be speaking on Polymer Applications for Excimer Lasers. The last meeting of the year will be on 24 May, when Professor Wiley Youngs of the Department of Chemistry at the University of Akron will speak on his recent pharmaceutical work.
Chairman Ernst von Meerwall announced that April is the month for submission of nominations for next year’s officers and requested that all such submissions go to Charlie Wilson, but cautioned that the nominee should be notified of his nomination and that he be willing to serve. Charlie reminded the group that E-mail correspondence would be used for this process.
At which point John Kirszenberg introduced our speaker, Clyde Simpson, of the Cleveland Museum of Natural History. After two years at the U.S. Naval Academy, Simpson opted for a stint in the Regular Navy, where he served as a navigator, specializing in celestial navigation. It was here, he says, that he caught his love of stars – and during the course of the evening, it showed. [During dinner, he passed around “the oldest thing we will ever touch”: a 4.5 billion-year-old iron meteorite left over from the Big Bang, together with an accreted stony meteorite.]
Having completed his naval service, Clyde enrolled at Cleveland State University, where he earned a degree in geology, doing studies on Venus and the moons of Saturn as a part of his course work. After several years of volunteering at the Cleveland Museum of Natural History he was hired as Director of the Ralph Mueller Observatory in 1984, during the passage of Halley’s Comet. In addition to coordinating the museum’s educational program, Simpson does daily solar monitoring for the Solar Section of the American Association of Variable Star Observers.
Our speaker’s subject was Astronomy at the Cleveland Museum of Natural History. Clyde gave a brief introduction of the Cleveland Museum of Natural History, especially the Astronomy Program and its striking new building, which includes a new Planetarium, complete with a dual hemisphere Zeiss Projector. The Museum also features an 1899 vintage, 10 1/2-inch Warner & Swasey refractor telescope, with a doublet lens.
Clyde’s description of the new Museum building focused upon the design of the Planetarium section which began as an architects drawing looking like a gasoline storage tank; but it ultimately became the frustum of a cone with the roof constituting the cut, and having its principal axis directed North at an angle of 41 1/2 degrees so that it points directly to the North Star. Thus the principal axis of the cut is parallel to the Earth’s rotational axis, making the building a naked-eye observatory as well as housing the Planetarium.
Illustrated with excellent slides, our speaker’s presentation then launched into an astronomical smorgasbord focusing first upon sunspots and radiating outward into Mars and Saturn probes, showing us what is thought to be photographic evidence of water on Mars and of atmosphere on Saturn – capped-off by some stunning Hubble telescope portraitures. Selections from the smorgasbord included:
An observation that astronomy is mostly observational rather than an experimental science. Getting to specifics, our sun is not a solid body, but exhibits differential rotational speeds from its equator (which is fastest, with a rotational period of 25 days) to its poles (with a period of only 27 or 28 days). [Note: One wonders if the Earth/Moon joint orbit might be related to those periods having been thrown from a central rotating body rotating at that rate.] Sunspot activity is cyclic with an 11-year period. Sunspots extend to ±40° latitude during periods of high activity receding to near the equator at times of low activity. The 11-year cycle is accompanied by a flip of the N/S poles of the Sun’s magnetic field.
Sunspots are magnetic storms that radiate great energy, especially when accompanied by solar flares. We are protected from the solar flare radiation on Earth and in Earth orbit by the Earth’s magnetic field. Astronauts venturing far from Earth, however, are at great radiation risk in the event of a solar flare. Our Moon missions in the late 1960’s and early 70’s occurred during a period of high Sunspot activity, which meant high flare risk, as well. Sunspots have been tracked since the late 1640’s when telescopes became numerous; however, frequency of sunspot occurrence was much lower in those times than now. [Note: One wonders if the significant increase in sunspot frequency in the past 150 years is real, or an artifact of education and better equipment and observation.]
Reference was given to the SOHO website (which means Solar & Heliospheric Observatory), which can be found at http://www.spaceweather.com Registration at that site will prompt E-mail to be sent to you whenever a solar flare occurs.
The Cleveland Museum of Natural History makes eclipse trips – the next one being to the rain forest in Costa Rica and Panama in late March of 2005 to see the annular (not annual) eclipse expected there then. The next sojourn after that will be in 2006 to Turkey for a total eclipse.
Turning to Mars and the rovers Spirit & Opportunity, Clyde commented that NASA would like to put such landers on Mars every two years in more water-rich sites. It is known that ice exists on Mars near its poles, but for a long time there was controversy surrounding whether such ice is dry ice or water ice and it is believed now to be water ice.
Our speaker showed us images of rampart craters, which differ from Moon craters because of the out-flow patterns that surround the crater – indicating that liquids (melted ice?) flowed following impact. Drainage systems have been photographed showing collections of smaller streams into larger ones as flow progresses downstream. These could also be underground rivers with the surface having depressed over the rivers, thus showing up on a telescope. We also saw pictures of perfectly spherical concretions (called “blueberries”) – 1 mm diameter spheres that have been found in Martian rocks by the current Mars rovers. These are formed only in the presence of water, our speaker said. Following the water subject a little further, Clyde mentioned that Europa, a moon of Jupiter, is thought to have a global ocean of liquid water beneath an outer crust.
Mars’ redness comes from the large content of iron oxide in the soil. It is, literally, rusty. [Note: Is that further evidence of water? Or at least of oxygen?] The 1976 Viking II Spacecraft carried a Mars Lander that scooped up soil samples and placed them into a portable lab on-site. TRW made three of these labs and two of them are now on Mars. The third one is at the Cleveland Museum of Natural History for viewing. Clyde showed a picture of what some think might be a bacterium fossil, having a tubular shape. Most observers, however, think it is not a bacterium.
Our speaker made a strong appeal about the importance of preserving the Hubble Telescope – an information-rich laboratory operating at its peak. He urged us to write our congressman to tell him not to trash it. Clyde told a story about his giving a talk on Hubble at a Seniors’ Home, telling his audience about Robert Breckenridge, a Case Western Reserve graduate who saved Hubble by redesigning its lens to compensate for its flawed mirror, and precipitating unexpected applause – later finding out that Robert Breckenridge’s mom was in the audience when she came up and thanked him for the recognition.
Clyde concluded his presentation by announcing that the Ralph Mueller Observatory telescope is open to the public every clear Wednesday from 8:30 – 11:00 PM – which amounts to 8 or 9 days a year, but that the public is cordially invited to come and see.
Questions (See Notes):
1) Is that 41 1/2 ° from the horizontal or vertical to the Planetarium roofline?
2) Is the 28-day Earth/Moon rotational period related to a similar rotational period for the Sun?
3) Has Sunspot activity really increased so significantly in only 150 years? That’s a mere instant in astronomical time.
4) Does Mars’ red color give evidence of water?
Jerry Potts (& Jack Gieck)
WE WELCOME VISITORS!
Meeting Announcement: MONDAY, April 26, 2004 - TANGIER, 6:00 PM
Having successfully passed through the vernal equinox (and the annual meeting of the American Physical Society) without significant damage, we are pleased to announce that the speaker for our first spring meeting this spring will be University of Akron’s Professor of Polymer Engineering Erol Sancaktar, who will be speaking on
Polymer Applications for Excimer Lasers
As explained by Google and Twente University: “Excimer stands for a diatomic molecule usually of an inert gas atom and a halide atom, which are bound in excited states only. These diatomic molecules have very short lifetimes and dissociate releasing the excitation energy through UV photons.”
Until now, however, excimer lasers (with a wavelength of 308 nanometers) have made their mark in medical applications, removing abnormal tissue without harming adjacent healthy tissue. Without generating heat, excimer lasers turn the abnormal tissue into a gas! But also: “Excimer lasers operating in the ultra-violet may be considered as the third generation of industrial lasers. The short wavelength, i.e., the high photon energy of excimer lasers, leads to a wide range of new applications . . .,” which, we gather, include polymer applications.
Minutes, April 26, 2004
Present for our April meeting were, Milian France, Dan Galehouse, Jack Gieck, Bob Hirst, Bill Jenkin, John Kirszenberg, Leon Marker, Pad Pillai, Jerry Potts, Darrell Reneker, Dick Sharp, Boyd Simmons, Dick Smith, Jack Strang, Ernst von Meerwall, Don Wiff, Charlie Wilson – and first-timer John Sommer of Hudson, an elastomer engineering consultant and author. Welcome, John.
Summoned by Chairman Ernst von Meerwall, Treasurer Dan Galehouse reported that our wealth had decreased from $80.38 to a new balance of $68.38 — no doubt to his relief, for it will constitute a lesser asset to guard while we all traverse the perilous gulf between the summer solstice and the autumnal equinox (for no bank will accept our trivial account). Which brought our agenda to meeting the annual April crisis of the election of officers for the coming year, whereupon Chairman Ernst called upon past-president Charlie Wilson, founder, and author of our bylaws for a report on new nominations. The campaign funds of would-be officers apparently having been in recession, Charlie advised that there were none — with the exception of a clarification of the office of Secretary, which will morph into team of three rather than four. The nominees proposed were, thus, to become:
|Chair:||Ernst von Meerwall|
|Program Co-Chairs:||John Kirszenberg & Bob Hirst|
|Program Vice-Chair:||Leon Marker|
|Co-Secretaries:||Jerry Potts & Jack Gieck|
|Reservations Secretary:||Charlie Wilson|
To get to the program for the evening, your secretary moved that the slate of candidates be accepted by acclimation. Duly seconded, the motion passed unanimously.
(All of which left out the very important non-elective office of Webmaster, so ably filled by volunteer John Kirszenberg [in addition to his other duties] — an office that no one else has admitted to having the qualifications to tackle. Thank you, John! We trust you will be willing continue to perform this vital service.)
It was Program Chair John Kirszenberg who introduced the speaker for the evening, University of Akron’s Professor of Polymer Engineering Erol Sancaktar, whose topic was Polymer Applications for Excimer Lasers.
Dr. Sancaktar began his talk with a definition of the word “LASER,” which acronym stands for “Light Amplification by Stimulated Emission of Radiation,” and he extended this padect into the origin of the Excimer LASER. “Excimer” is a contraction of "excited dimer," a diatomic molecule usually of an inert gas atom and a halide atom, which are bound in excited states only. These diatomic molecules have very short lifetimes and dissociate releasing the excitation energy through UV photons. The wavelength of such UV light is very short, on the order of250 -- 300 nm.
Being an engineer by training, our speaker explained that his interest is in applications rather than the basic science involved in the LASER processes; thus he would address the "what can be done" with Excimer Lasers rather than the "why" or "how." LASER applications usually bring to mind either Holography or ablative uses, the latter being the melting or blowing-away of unwanted materials caused by the conversion of the very intense light energy directly into heat as the target material absorbs the light. Enough such heat will boil, melt, or otherwise physically change the material, usually removing it from substrate material which may be the same or different.
Excimer Lasers can be used in the same way, but the target material is not necessarily altered in the usual physical sense. Instead of heating the target material, the short wavelength light can actually alter the molecular bonds within the target thus making chemical changes through a physical process, which is most extraordinary. This is the primary application in medical uses of Excimer Lasers so that target cells can be killed or removed by releasing their molecular bonds without harming (heating) surrounding healthy tissue.
Polymer Science applications tend to be either in the area of adhesion for polymer processing, or in the measurement of residual stress effects for injection molding. There is no inherent limit in these applications. Indeed, any process that may be affected by surface profile or molecular bonds and which can be irradiated by the LASER are candidates for modification by Excimer LASER treatment. The field is wide-open for such processes and now is an exciting time for Excimer technologists.
Wavelength of the Excimer radiation and size of the molecular bonds are important considerations in polymer applications leading to the notion of the absorbency of the polymer for a given Excimer wavelength. Without such absorbency, there is simple transparency and the light passes through the polymer without effect. Once absorbency has been established, the molecular bond energy may be matched by the LASER beam energy in order to produce resonance within the bonds.
Basically, there are three ways the polymer may be affected:
1. Change the molecular structure on the surface being irradiated
2. Remove material (ablation) by breaking cross linking bonds
3. Melt the material
The first of these was illustrated by Prof. Sancaktar in his experiments with the peel strength of polypropylene tape applied to glass plates. He irradiated the adhesion interface from the glass side using the Excimer LASER at various intensities and for various times and noted a significant increase in peel strength following irradiation, indicating increased polymeric cross linking at the interface.
Another application involved increasing the surface roughness of polymers prior to ultrasonic welding. Excimer LASER irradiation provides such an increase in surface roughness, making the polymer melt more easily at the weld interface by increasing the surface to volume ratio, thus accepting ultrasonic heating more readily. This has been so successful, in some instances, that materials which had no weldability, such as styrene plastic, suddenly become easily weldable. Others showing significant improvement are ABS and PTP.
Dr. Sancaktar had mentioned that the Excimer provides not only processing possibilities, but also measurement capabilities, largely through the same processes described above, namely in the ablative uses. An example of this is in the sensing of residual stresses in injection molded products. It is well known that the material near the bottom of the mold will have lower residual stresses than the material near the mold gate, since there will be less flow turbulence in that region. Photoelastic samples of a polystyrene molded product were made from the material near the bottom and near the gate of a mold to show the isochromatic stress patterns locked into the material and caused by residual stresses. The Excimer LASER was then employed to ablate some of the surface material in a molded part both near the bottom of the part and near the mold gate. Less energy was required to remove material near the gate than near the bottom in proportion to the residual stresses seen in the isochromatic patterns, making this a simple procedure to employ for measuring such residual stresses.
Since the Excimer can be controlled on such a small scale, there are a host of applications just waiting to be discovered in the field of nano-technology, which is tomorrow's new buzz-word, only being concepted today.
Prof. Sancaktar's enthusiasm for this new field of study showed all during his presentation, especially with his effort to cover all aspects of his research. It was readily apparent that this will not be possible much longer, for, although the field may be new, it is moving at a very fast pace and accumulating so much new knowledge that describing it all in one session is already nearly impossible. It was quite a treat to hear from one who will, no doubt, soon be regarded as a pioneer in this area of Polymer Science.
WE WELCOME VISITORS!
Jerry Potts & Jack Gieck
Meeting Announcement: May 24, 2004 - TANGIER, 6:00 PM
For the last meeting before the inevitable summer hiatus, our speaker will be Professor Wiley Youngs of the University of Akron’s Department of Chemistry, whose talk has the unlikely title of:
Pharmaceutical Work with Silver and Rhodium N-Heterocyclic Carbene Complexes of Silver
Asked how he got interested in such a subject, Dr. Youngs explained that when he attended the 2000 meeting of the American Chemical Society in San Francisco, he heard a talk on radio-pharmacy tools, some of which tend to migrate to specific body locations. Radioactive iodine, for example, collects in the thyroid gland, achieving a 95% cure rate for thyroid cancer. This set our speaker to thinking about sequestering radioactive metals, e.g., radioactive silver (Ag111, which has a half life of about a week), that might not only be effective against cancer, but silver he noted also has antimicrobial properties. A specialist in cystic fibrosis at Case Western Reserve Medical School is interested Dr. Youngs’ work.
Minutes, May 24, 2004
Present for our May meeting were Marie and Tom Brooker, Dave Brown, Bill Dunn, Dan Galehouse, Jack Gieck, Bob Hirst, John Kirszenberg, Leon Marker, Jerry Potts, Darrell Reneker, Dick Sharp, Boyd Simmons,* Jack Strang, Ernst von Meerwall, and Charlie Wilson.
After an unavoidably late start,* Chair Ernst von Meerwall asked Treasurer Dan Galehouse for a report on the state of the club’s treasury. It turned out that, true to form, Dan had managed to finish the evening with a net gain of exactly one U.S. dollar – resulting in a balance of $69.38 to be guarded (in its polyethylene/polypropylene box) over the summer months. However, in a subsequent communiqué, Dan has advised that occasional club member Dr. Bill Arnold, a former student of Dan’s who is now out in the non-academe world, has contributed a fund of $100 to pay for attendance of students who might like to come to Club meetings.
Asked by Chairman Ernst for any additional items on the evening’s agenda, your secretary reminded the group of a series of two musical plays, authored by club-member/ film-writer Milian France — the first one premiering at the Actor’s Summit Theatre in Hudson, June 27, 28, 29. See Milian’s spectacular website: http://www.pianobarlive.com for further details.
Which brought us to the introduction of our speaker, Professor Wiley Youngs of the University of Akron’s Department of Chemistry (where he has been since 1990), whose talk was announced with the unlikely title of: Pharmaceutical Work with Silver and Rhodium N-Heterocyclic Carbene Complexes of Silver — AKA Heterocyclotriynes, a project funded by the National Science Foundation.
Explaining how he got interested in such a subject, Dr. Youngs related how, when he attended the 2000 meeting of the American Chemical Society in San Francisco, he heard a talk on radiopharmacy tools, substances which tend to migrate to specific body locations to deliver therapeutic radiation. This set our speaker to thinking about sequestering radioactive metals, e.g., radioactive silver, rhodium, and other metals that might not only be effective against cancer, but against bacterial infections as well.
N-Heterocyclic Carbenes are cyclic carbon compounds. But unlike the familiar benzene ring having a hexagonal structure, carbenes take the shape of a pentagon. Typically, the pentagon has a pair of carbon atoms across the bottom joined by a double bond; it has nitrogen atoms at the outside corners, each joined to an external R– (alkyl) group; and the carbon atom at the point on top has a pair of unshared electrons, a “ligand,” that readily bonds to a metal.
The strategy is to strongly (perhaps irreversibly) bond a medicinally useful metal to the ligand. For magnetic resonance imaging, for example, manganese could be the choice (because it induces spin relaxation of the proton). For positron imaging tomography a radioactive metal would be useful if the molecule can be delivered to a particular organ to be studied (and only to that organ).
Dr. Youngs recent work has concentrated on silver (Ag111) a radioactive beta emitter which has a half-life of 7.5days – almost identical to that of radioactive iodine (I131), another powerful beta emitter which naturally targets the thyroid, and which is responsible for the 95% cure rate for thyroid cancer. Silver, moreover, has antimicrobial properties. But the problem with silver is that it does not have a natural target in the body as I131 does. To achieve this end, a side chain of the ligand can be linked to a peptide (a short protein or amino acid) moiety – one having a configuration that naturally targets cells (ideally cancer cells) in a particular part of the body – (the word “moiety” originally referred to clans that are attracted to each other). A strong silver carbon bond is essential so that radioactive silver is not deposited in some unintended part of the body – at least not until the expiration of several half-lives, when the radiation gets down to near background level.
Achieving such a goal is complicated by body chemistry. For example, if a water-soluble silver compound is injected into the bloodstream, which naturally contains a substantial amount of sodium chloride, the precipitation of insoluble silver chloride is very likely. There are other intrinsic problems to be solved: Because of its very short half-life, Ag111 does not exist in nature, but must be produced in a nuclear reactor. So the process of hooking it up to a carbene ligand must be simple and quick, and must not have too many steps – a reaction that must be simple enough to be done in a nearby hospital environment by personnel who are not research chemists. And the compound must not be too unstable to be practical. Accompanied by beautiful Power Point graphics, Dr. Youngs described a series of candidate reaction systems with silver carbenes as well as some in combination with other metals.
Our speaker pointed out that the antimicrobial properties of silver have long been recognized – going back to the ancient Persians, who transported water in silver jugs; the Romans put silver coins in their water systems to keep bacteria from growing. In fact, silver continues to be used today by NASA to control the growth of bacteria aboard the space shuttle. Roman pharmacopoeia of 76 BC list silver nitrate as a substance for healing wounds – a technology that was lost until 1895 when the silver salt began to be used to cleanse the eyes of newborn babies, 15% of whom were going blind at the time from infections they had picked up in the birth canal. Indeed, silver nitrate was used on burn patients as late as 1965 to prevent infection.
So, using silver nitrate as a standard, Dr. Youngs presented a series of Petri- dish/filter paper slides evaluating the effectiveness (against both bacteria and fungi) of a number of the silver carbene complexes he and his students have developed. The results were impressive. Our speaker went on to show us the effectiveness of combining products of this kind of chemistry with electro-spun nano-fibers (a technology with which the club is familiar, thanks to programs by member Darrell Reneker and others) spraying the silver carbene complex onto a pad of tecophilic© fibers and achieving bondage. (“Tecophilic” is Professor Reneker’s copyrighted trademark for a polyurethane polymer able to absorb water in copious quantities – useful in wound treatment.) As it turns out, for topical application to wounds, the resulting teco-silver fiber mats have three times the effectiveness of silver nitrate in preventing infection, even when using substantially lower concentrations.
Promising ongoing research in Dr. Youngs’ group involves radioactive rhodium (Rh105), with a half-life of 36.4 hours – and on the other side of the molecule, caffeine and histamine systems, which are obviously very compatible with human metabolism. It would seem that Wiley Youngs’ inspiration at the West Coast ACS meeting four years ago was a good idea.
* As we began dinner, for the second time in recent months, Akron paramedics were summoned to the club. But this time things did not turn out well. As announced in our e-mail of May 29, a regular at the Akron Physics Club since September, 2003, Boyd Simmons died of a massive heart attack on May 24, 2004. Boyd had retired as a professor at Delgado College in New Orleans after 26 years of teaching. He was a World War II Veteran and a 32nd Degree Mason. A memorial service for him was held Thursday, June 3, 2004, at the Unitarian Universalist Church.
Meeting Announcement: MONDAY, September 27, 2004 - TANGIER, 6:00 PM
Celebrating the autumnus aequinoctium six days late this year [after all, Newton wrote in his Principia in Latin] we will open the new season with our own Prof. Darrell Reneker, who will be describing [in English] some recent
New Developments in Electrospun Nanofibers, e.g. WOUND DRESSINGS
Minutes, September 27, 2004
Gathered to hear our speaker at the first Fall meeting were Dave Brown, Tom Dudek, Bob Erdman, Sam Fielding-Russell, Dan Galehouse, Jack Gieck, Bob Hirst, Bill Jenkin, Milian France, Jonah Kirszenberg, Leon Marker, Jerry Potts, Darrell Reneker, Dick Sharp, Ernst von Meerwall, Don Wiff, Charles Wilson, and Wiley Youngs, who was our last speaker before Summer break. Welcome aboard, gentlemen!
In our short business meeting Treasurer Dan Galehouse advised that our wealth had increased $2.00 since last month, resulting in a stunning new balance of $71.38!
Program Co-Chairman John Kirszenberg outlined next month’s meeting program, to be held on 25 October, which will be a talk by Prof. Arnold J. Dahm, Emeritus Professor of Physics - Case Western Reserve University, who will be addressing the Club on:
"Building a quantum computer with electrons floating on a surface of liquid helium".
Prof. Dahm has an NSF project whose goal is to construct a quantum computer. His areas of specialty are condensed matter experiments and low temperature physics.
John then announced that speakers are still being sought for the 22 Nov. and 24 Jan. meetings, but that plenty of candidates appeared to be available.
A new member, Bob Erdman, was introduced by Charlie Wilson. Welcome Bob! Charlie also announced that Dave Wynn’s father had recently passed away and wanted club members to be aware of his loss. And Charlie informed the group that his mother-in-law had also recently passed at age 106. We should all be so fortunate as to do as well.
Chairman Ernst von Meerwall introduced the evening’s speaker, our own Dr. Darrell H. Reneker, whose resume was more formally addressed than usual, describing his completion of a BSEE at Iowa State University, followed by an MS and then a PhD from the University of Chicago in 1959. After periods at the Bell Telephone Laboratories, Dupont and NIST, he came to the University of Akron as Director of the Institute of Polymer Science in 1989. His topic for our September meeting was New Developments in Nanofibers (e.g. Wound Dressings).
Professor Reneker once again boggled our minds, and our retinae, with images of nanofibers created by the electro-jet spinning process that he has been developing during the past ten years, reminding us that, compared to a human hair, his nanofibers look like spider webs on a hawser for mooring ships (being as small as 3 nm, which is 6 molecules, in diameter!). He began by reviewing the electrospinning technique, showing that fiber sizes and spinning techniques have not changed appreciably from those he described in his APC presentations of 1997 and 2000. But seeing the mechanism whereby static electricity overcomes surface tension, causing a droplet to splay into branching chains of nanofibers, continues to be fascinating.
Dr. Reneker further pointed out that he did not invent the basic spinning process and that it had been reported as early as 1917 with applications to sealing wax, then later was patented in both Germany and the USA in 1934; however, there was little interest in it at that time because of the development of rayon, nylon, and other synthetic textile fibers — with commercial interest being concentrated in these much larger fibers. There has been a greatly accelerated interest in the electrospinning of nanofibers during the past decade, as evidenced by the fact that when Darrell first published his processes in 1994, there were only two or three such papers published. By 2000 there were 25 papers being published per year — half of these were done at Akron U. In 2001 there were 50 papers, and by 2003 over 1000 technical papers were presented on the subject. It is apparent that Darrell started something!
What is currently more interesting than the spinning process is the discovery that various constituents may be placed into the mix being supplied to the spinning jet in order to produce a virtual miniature chemistry laboratory that either reacts with the miniscule fibers as they spin, or encapsulates them for later distribution. The resulting fabric created by the spinning and deposition process has created an interest in wound dressings, which can, for example, release beneficial nitric oxide directly into a lesion upon activation of the dressing by water. Such is currently being used experimentally to treat Sand Fly sores, which occur in parts of Africa and mid-East countries, including Iraq. The beneficially high surface-to-volume ratio, which makes nanofiber fabric so attractive as a filter with great absorbency, thus also makes it an efficient distributor of material that has been built into the fiber itself. That, along with the possibility of spinning the fiber directly onto a wound site for maximum intimacy of contact, makes for really exciting new methods of medicine delivery.
Other applications were also noted and arise from the use of different materials and different jet patterns that are achievable in the spinning process, such as ceramic nanofibers being excellent hosts for rare earth ions. Here the high surface area allows rapid heat absorption. Garland-shaped nanofiber patterns can thus be created by having the electrospun fiber jet cross itself repeatedly while still wet. As the carrier solvent evaporates, a garland of nanofiber remains. Electrically conductive nanofibers can be created using conductive polymers as the main ingredient in the spin solution.
This field is currently expanding quite rapidly and it was gratifying to the group to be included in “what’s going on” in a cutting-edge technology that is currently being considered for applications as far out as solar sails on space vehicles.
WE WELCOME VISITORS
Jerry Potts & Jack Gieck
Meeting Announcement: MONDAY, October 25, 2004 - TANGIER, 6:00 PM
Speaker for our October program will be Prof. Arnold J. Dahm, Emeritus Professor of Physics, Case Western Reserve University, who has a National Science Foundation grant with the unlikely goal of
Building a Quantum Computer
With Electrons Floating on the Surface of Liquid Helium
It is reassuring to some of us that before presenting his design for such a computer, Professor Dahm will first give us “a brief review of some aspects of quantum mechanics and an introduction to quantum computing,” His design of is based on electrons localized above a helium film as quantum logic elements — “qubits.” “Each qubit,” he explains, “is made of combinations of the ground and first excited state of an electron trapped in the dielectric image potential well at the surface. Voltages applied to an array of micro-electrodes beneath the surface restrict the lateral motion of electrons and are used in entering data and operating quantum gates. Got that so far?
Minutes, October 25, 2004
No doubt drawn by our speaker’s announced topic, a healthy-size group turned out for our October meeting. It included Tom Brooker, Dave Brown, Stu Clary, Bill Dunn, Bob Erdman, Sam Fielding-Russell, Milian France, Dan Galehouse, Jack Gieck, Bob Hirst, Bill Jenkin, Leon Marker, Jerry Potts, Darrell Reneker, Dick Sharp, Jack Strang, Ernst von Meerwall, Don Wiff, Charlie Wilson, and Wiley Youngs.
Called upon by Chairman Ernst von Meerwall, Treasurer Dan Galehouse announced somewhat reluctantly that, due the size of our attendance, our wealth had grown by another $5.00, and was now tipping the scales at $76.38. The signal event was followed by Co-Program Chairman Bob Hirst’s reporting that we now have speakers engaged for November (see above), January and March of 2005. In January, we will hear from, Dr. David S. Perry, Professor and Chair, Department of Chemistry, The University of Akron. His topic will be Molecular Dance Steps: New Kinds of Vibrational Motion Born at High Levels of Excitation.
Our speaker for the evening was Professor Arnold J. Dahm, Emeritus Professor of Physics, Case Western Reserve University, who has been working for four years on the daunting task of Building a Quantum Computer with Electrons Floating on the Surface of Liquid Helium.
Our speaker began by justifying his quest. It’s not, he explained, just because of the popular myth that “quantum computers are the next thing.” Quantum computers should make it possible to quickly search very large data bases. To find out to whom a telephone number belongs, for example, one has to go through an entire telephone book. Quantum computers could shorten the time enormously by looking at a number of numbers simultaneously. Quantum computers should be capable of factoring very large numbers very quickly. Numbers with a hundred digits could be factorable in about a second (as opposed to a couple of months with present equipment) — very useful for encryption applications for the military. But perhaps their best reason for being was exemplified in two delightful poems that Dr. Dahm presented on the screen.
What followed was a brief overview of some aspects of quantum mechanics and an introduction to quantum computing, before getting into Arnold’s design, which is based on electrons localized above a helium film as quantum logic elements — “qubits.” Each qubit, he explained, is made of combinations of the ground and first excited state of an electron trapped in the dielectric image potential well at the surface. A quantum computer incorporates a set of individual cubits. Each of these has two stationary states of a quantum system as counterparts of the classical computer bits: 0 and 1. Voltages applied to an array of microelectrodes beneath the surface restrict the lateral motion of electrons and are used in entering data and operating quantum gates.
We acquired a concept of what one of these devices could be like, beginning with a substrate into which tiny pins 1.5 microns high (made of a gold film on silicon) would be emplaced on 0.5 micron centers. This substrate would be covered by a film of liquid helium one micron thick so that the “posts” stick up half a micron above the surface. Suspended above the helium surface is a 100 gigahertz electron gun. As a noble gas, the helium atom is a closed shell (with two electrons in its “orbit”) so it repels the electrons, that are suspended, one electron above each post at an “altitude” of 15.3 nanometers above the helium surface for state Z1 (0) and 61.2 nm for Z2 (1). It takes 70 GHz to go from an energy level of 0 to 1. Presenting an artist’s concept of such a (16-bit analog) computer in the real world, Dr. Dahm described the resulting sandwich as being about one millimeter thick. Thus the computer would fit into the hull of a grain of rice; however, since such a microcomputer would be operated by a classical computer (and attached by all those tiny wires), it is not likely to be lost.
That’s a very simplified overview of a concept that in the real world turns out be lots more complex. It includes such factors as evaluating needed magnetic moment or “spin,” calculating the energy needed to convert cubits from an “entangled” state to a more meaningful one, and the mathematics for calculating the “probability” of the very weakly bound electrons being suspended at a predicted height. Then we have proposed mechanisms for one and two-qubit logic operations as well as mechanisms for a simultaneous readout of the final state of all qubits.
There are, it seems, a variety of quantum computer concepts currently being explored that differ from those being worked on by Arnold Dahm and his associates (who are, incidentally, scattered across the country). He thinks these concepts will sort themselves out, but that it will be twenty years before 100-bit quantum computers become a reality. That some members of the audience were really with his subject was evidenced by the number of knowledgeable questions that punctuated our speaker’s presentation.
WE WELCOME VISITORS
Meeting Announcement: MONDAY, November 22, 2004 - TANGIER, 6:00 PM
Speaker for our November meeting will be Professor Sadhan Jana, Department Chair of Polymer Engineering, the Akron University of Akron. Dr. Jana’s topic will be:
From a Perspective of
Infrared Spectroscopy and Rheology
Minutes, November 22, 2004
Once again filling three tables, our turnout included regulars Dave Brown, Tom Dudek, Bill Dunn, Milian France, Dan Galehouse, Jack Gieck, Llyoyd Goettler, Bob Hirst, Bill Jenkin, John Kirszenberg, Leon Marker, Darrell Reneker, Dick Sharp, Jack Strang, Ernst von Meerwall, and Charlie Wilson. Whereupon Reservations Secretary Wilson introduced Bill Dunn’s guest Ron Krishnan, newcomer Derek Shuttleworth, and Bill Arnold’s invitee, Justin Bail. Welcome aboard, gentlemen. We hope to see you in the future.
And speaking of Bill Arnold, Charlie announced that Dr. Arnold has sent a contribution of $100 to the club, designated to pay for the dinners of University students who might like to attend our meetings. Charlie and Ernst have both written him letters of thanks.
Although recognizing that the response would be embarrassing to Treasurer Dan Galehouse (whose continued hopes for steady-state stability of our treasury were being dashed once again), Chairman Ernst von Meerwall nevertheless called upon him for a report of the club’s current wealth. Treasurer Dan reluctantly announced that attendance once again had resulted in a profit – this time in the amount of $3.00, further swelling our treasury’s total from $76.38 to a new balance of $79.38, (thus increasing his responsibility for maintenance of the cash he carries in a strongbox since, despite earlier pleas, no bank will accept such a measly account).
Before introducing our speaker, Chairman Ernst noted that he would ask Bill Arnold to be a speaker – and if he is successful it will behoove us to invite one or more students for the occasion!
At which point Ernst introduced Professor Sadhan Jana, who recently became Chair of the University of Akron’s Department of Polymer Engineering. Dr. Jana, a chemical engineer, would speak on his specialty, Polymer Nanocomposites, From a Perspective of Infrared Spectroscopy and Rheology.
Accompanied by some stunning Power Point graphics (projected by an equally impressive $4000 magic lantern not much larger than a ciabatta roll), our speaker began with an image (replete with websites) that demonstrated the ubiquitousness of polymers in common applications ranging from athletic shoes and roller blade wheels to Plexiglas, sports surfaces, and cosmetic foundations. Most of these involved thermoplastic polyurethanes, the polymer which has been the focus of Dr. Jana’s nanocomposite research. These polyurethanes are a polyol-isocyanate multi-block copolymer having a molecular weight of 60,000 to 120,000.
Products manufactured from such polymers have a wide variety of physical property demands — toughness and strength often topping the list. To this end, Dr. Jana’s group has been working on nanocomposite design using nanofillers and processing ingenuity to adjust the modulus, strength, and elongation of the resulting polymer, using clay nanofillers. (He reminded those of us who are rubber company veterans that carbon black is a nanofiller — one which dramatically influences the modulus and elongation of rubber compounds.)
By building a tethered chain with alternating soft and hard segments in a nanoclay-polymer he has found it possible to increase the strength of the polymer while keeping the modulus and elongation unaltered. Through changes in processing techniques, including the order in which the ingredients are added as well as the temperature at which the clay-polymer reactions take place, he has found it possible to control not only modulus, strength, and elongation, but also tear strength, abrasion resistance, and even relative transparency. With some excellent Power Point diagrams, Dr. Jana illustrated three solventless methodologies in which the order of adding ingredients, particularly the with regard to the nano-thin clay layer, was varied. Abbreviated, these methods included:
3: Diisocyanate/polyol/ butanediol —>prepolymer—>clay—>nanocomposite
There followed tables of the effects on physical properties resulting from each process. We also saw some scanning electron microscope images showing how the buildup of viscosity during the process can have a significant effect on the uniformity of dispersion of the clay filler by affecting the shear value of the mix. Photomicrographs showing uniform distribution of clay nanofibers contrasted with “large” black lumps of undisbursed opaque clay.
The conclusions drawn from Dr. Jana’s experimental processing work included (1) both clay-polymer tethering reactions and shear forces are required for better dispersion of clay particles; (2) hydrogen bonding and clay-polymer tethering provide mechanical strength; and (3) analysis of WTS, TEM, and DSC reveal the possibility of intra-particle looping in the first of the three methods. Thus, Method 2 turned out to be best.
A reminder that not only do WE WELCOME VISITORS, but WE ALSO WELCOME STUDENTS — thanks to Dr. Bill Arnold who has already paid for their dinners!