Akron Phy
sics Club



Archive 1994
 

               
1994  
January  Bob Hirst - Detecting Sulfur Crosslinks in Cured Natural Rubber wSolid State NMR Spectroscopy  
February  Donna Galehouse - Recent Advances and Future Prospects in Molecular Biology
March  Alan Gent - Adhesion
April  Vernon Neff - Solid State Chemistry
May  Georg Böhm - Radiation Effects on Polymers and Applications Thereof
September  Ernst von Meerwall - Using NMR for (1) Imaging and (2) Velocity Measurements
October  Donald Palmer - Journey to the Center of the Earth: The Earth’s Interior and Getting Information About it
November  Peter Renaldi - Capabilities of Modern NMR Spectroscopy

 

 

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Akron Physics Club

Newsletter


Meeting Announcement: MONDAY, January 24, 1994 - TANGIER, 6:00 PM



FOR THE FIRST MEETING OF THE NEW YEAR, our own BOB HIRST will speak to us on a topic that was the subject of the Nobel Prize in the 1950s. For corporate reasons, he is obliged to use the longest title in our club's history:

DETECTION OF SULFUR CROSSLINKS IN CURED NATURAL RUBBER USING SOLID STATE CARBON-13 NMR SPECTROSCOPY


Minutes, January 24, 1994

     In attendance to hear our own Bob Hirst at our first meeting of the year were Aggie Aggarwal, Tom Dudek, Dan Galehouse, Alan Gent, Jack Gieck, Bob Harrington, Bob Hirst (even though he had heard the talk before), John Liska, Leon Marker, Pad Pillai, Irv Prettyman, Darrell Reneker, Jack Strang, and Charlie Wilson.

     With a plethora of excellent slides in both 35mm and overheads, Bob first showed us his workplace, featuring an electromagnet comprised of some 8-10 miles of wire, operating in a helium bath (immersed by a nitrogen bath) to achieve superconductivity. The magnet was charged up in March 1985, after which the power supply was removed, leaving some 231 X 1018 electrons per second (or 37 amperes if you prefer) swirling dizzily around the coil for the last nine years.

     Bob convinced us that with roots going back to 1936, the NUCLEAR MAGNETIC RESONANCE spectrometer has become an absolutely magnificent toy, capable of sorting out structural details in polymers of every ilk. In natural rubber, for example, the device can not only detect sulfur cross-links as bonding occurs between chains, but it can count them, making quantitative measurements of carbon-sulfur units. A skilled interpreter of the data like our colleague can also estimate the number of dangling Sx units, and can quantify relative cis/trans isomerization (as a function of the amount of curative and/or cure time) as well as the formation of methyl end groups during cure.

     For some of us, the sophistication of the device turns out to be almost as interesting as the results it makes possible. Rotating in a little sapphire cylinder of slightly less than 1 cm diameter, at the "magic spin angle" of 54o 44' (to average out internuclear interaction) at 240,000 rpm (that's 4K Hz) or even higher, while being subjected to RF pulses in the range of 75 MHz (that's between TV Channel 3 and Channel 4) while sometimes being cooked at temperatures between 55 and 200o C, the sample is tortured into yielding values (and mountain range plots) that are a measurement of T1, spin lattice relaxation time, chemical shifts, and other nuances. At 300 MHz, decoupling of protons from carbon-13 nuclei occurs, and the resolution of the plots improves substantially.

     For those of us who are rubber industry alumni but who new little more about NMR technology than what the initials meant and, vaguely, how the machine worked (as distinguished from the several who have devoted most of their lives to its pursuit) Bob's program was a revelation and a delight.

* * *

     Innovatively, our FEBRUARY MEETING will feature a very good friend of our treasurer. DR. DONNA GALEHOUSE, head of the Molecular Biology Laboratory of Children's Hospital, will speak to us on:

     RECENT ADVANCES AND FUTURE PROSPECTS IN MOLECULAR BIOLOGY


PLEASE!! CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, February 24th (because I must call them in Friday morning). And please don't forget to cancel if you must. The club gets charged for no-shows.

Jack Gieck
Secretary

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Akron Physics Club

Newsletter


Meeting Announcement: MONDAY, February 28, 1994 - TANGIER, 6:00 PM



Innovatively, our FEBRUARY MEETING will feature a very good friend of our treasurer. DR. DONNA GALEHOUSE, head of the Molecular Biology Laboratory of Children's Hospital, will speak to us on:

RECENT ADVANCES AND FUTURE PROSPECTS IN MOLECULAR BIOLOGY

PLEASE!! CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, February 24th (because I must call them in Friday morning). And please don't forget to cancel if you must. The club gets charged for no-shows.


Minutes, February 28, 1994

     Despite the lure of Florida (or that of the hearth on a February eve), we counted Aggie Aggarwal, Mark Dannis, Tom Dudek, Dan Galehouse, Jack Gieck, Bob Harrington, Bob Hirst, Dan Livingston, Leon Marker, Pad Pillai, Irv Prettyman, Darrell Reneker, Jack Strang, Ernst von Meerwall, Don Wiff and Charlie Wilson in attendance at our second meeting of the year. The group learned about good things that have happened to two of our absentees (who were attending a farewell party) and to another illustrious member who was present:

     Georg Bohm has become Bridgestone/Firestone's Director of Research; and Joe Walter is on his way to Rome to become Managing Director of the company's European Technical Center. Joe sent along his sincere regrets about his having to miss the fellowship of our group for a while. Further, we congratulated Ernst von Meerwall on becoming head of the University of Akron's Physics Department.

     Our excellent winter attendance was, no doubt, in anticipation of our program by Dr. Donna Galehouse, who opened a new world to many of us: MOLECULAR BIOLOGY -- the organic software that is us. Encouraged by some of you, in attempting to summarize the concepts Donna laid on us, your secretary will pretend that some other members were as vague as I about this field of knowledge before meeting our speaker; and, especially for absentees, will take the liberty of translating some of what we heard into what I hope is physicese.

     Scaling down from DNA, which carries hereditary information from generation to generation, and RNA, which delivers the instructions encoded in this information to the cell's manufacturing sites (messenger RNA and structural RNA), we learned about four nucleotides (thymine, adenine, cytosine, and guanine) -- which are the monomers that form nucleic acids. Donna showed us the structure of DNA: very long linear strings of genes (whose components are chromosomes) geometrically arranged in the famous double helix, held together in parallel by the relatively weak zipper of hydrogen bonding -- a kind of coveting of the hydrogen in the adjacent string by the carbon (especially atoms already involved in a double-bond carbonyl affair), oxygen, or nitrogen in the polymer's twin [complement to the initiated].

     Donna told us how she separates these chemical Siamese twins (and persuades them to grow to a billion copies in 32 generations) by raising their temperature to 94o C(!), thus denaturing them -- kicking out gene segments in the process that represent the seeds of specific tissues, e.g., smooth muscle, striated muscle, three varieties of brain tissue, etc., adding enzymes and a primer to stimulate growth (polymerization), and sometimes rearranging strands into new pairs before reannealing them into new generations of DNA double helices containing as many as 3 X 109 base pairs. Stretched out, these incredibly long (each unique to the individual) molecules would measure about 5 cm in length -- posing a considerable a problem for topologically oriented biologists.

     To sort out the components of the string (the kicked out genes), Donna and her colleagues use electrophoresis, which can be compared in concept to both electroplating and chromatography. Colloidal particles being electrically charged (it is their mutual repulsion that keeps them in suspension) move toward the oppositely charged electrode when 2000 volts is applied across a gel containing the DNA. The smaller particles move faster through the retarding viscosity of the gel, providing the separation needed to physically identify the components by their relative positions, reading out the results in a display analogous to a that of a gas chromatograph.

     We also learned the fundamentals of cloning (albeit from a single fertilized egg) -- the maximum replication for this technology at the moment being octuplets. No dinosaurs from a random blood sample so far, but Donna advised that researchers have been successful in cloning an entire carrot. Which seems reasonable to those of us who sort of cloned both entire carrots and entire radishes (albeit from fertilized seed) in our back yards when we were kids.

     All of which makes some of us ask yet again, whence the design factor in the evolution of such incredible complexity (that we are led to believe emerged spontaneously from that green slime in those warm ponds long ago)? Mr. Darwin's thesis is obviously an excellent sieve for the unfit. But whence this wildly complex creativity flying in the face of the second law of thermodyamics -- driving entropy backwards from chaos to ever more intricate order? Institutionalized religions offer little help in this regard, since their Creator must also be credited with designing the metamorphosis of such clever diseases as malaria, Bubonic plague, and rabies (with their interim generation dependency on mosquitoes, rats, and other friendly living environments), as well as a whole host of ingenious parasitic viruses that resemble loose genes with their own agenda. Products like these sound more like the inventions of Loki than the popular loving God.

     As the King of Siam said (or sang), "Is a puzzlement!" -- and, I submit, a legitimate concern of physicists, and of this engineer (who begs your leave to occasionally use this monthly column as a bully pulpit). Quantum physics pales by comparison to this grand puzzlement. Although Socrates demonstrated that the role of a gadfly is not to be envied (especially after accepting that drink), this one welcomes comments from members who choose to address the issue.

Jack Gieck 
Secretary

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Akron Physics Club

Newsletter


Meeting Announcement: MONDAY, March 28, 1994 - TANGIER, 6:00 PM



Speaker for our March meeting will be our own ALAN GENT, world class rubber scientist (and a member of the commission, together with Richard Feynman, who investigated the Challenger disaster), who is currently in the University of Akron's Polymer Engineering Department. Alan will speak to us on the nature of:

ADHESION

Please CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, March 24th (because I must call them in Friday morning). And please don't forget to cancel if you must. The club gets charged for no-shows.


Minutes, March 28, 1994

     At our March meeting, speaker Alan Gent, speaking on ADHESIVES, attracted a record attendance that included Aggie Aggarwal, Georg Bohm, Tom Dudek, Ron Eby, Dan Galehouse, Jack Gieck, Bob Harrington, Bob Hirst, Dan Livingston, Leon Marker, Pad Pillai, Irv Prettyman, Darrell Reneker, Jack Strang, Ernst von Meerwall, Don Wiff and (a somewhat ailing) Charlie Wilson, who reports he is feeling better.

     "All adhesives," Alan told us for openers, "are polymeric."

     Our speaker demonstrated (with a roll of ScotchR tape) that what we used to measure under classic rubber industry procedures for quantifying bond strength was not very well thought out. Simplistic measurement of the forces needed to fail the bond in shear or in peel were always notoriously inconsistent. This, he explained, is because the force needed to separate a product strip from its substrate is not constant, but depends on the speed (as anyone who has had his bandage suddenly removed by a nurse can loudly proclaim!).

     Alan showed us a family of curves which plotted this force vs. the rate of peeling at a variety of temperatures (things coming to a screeching halt at -40o). What one is really measuring here, he explained, was a function of the viscous nature of the polymer -- which is directly related to its Brownian motion. The sensible approach to measuring adhesion, then, is to measure the energy required to separate the bond. Indeed, most of the energy involved is in dissipative processes, our speaker revealed, not in breaking bonds. Thus, in the equations Gent laid on us relating to the shear failure of a single tire cord, the force is always squared, e.g.:

     P2 = 4 ArEGa

     (in which r is the fiber radius, A is the area of the matrix, E is the modulus, and Ga is the fracture energy in joules per square meter)

     The force, thus, goes up as the square root of Young's modulus, and as the square root of the number of cords -- leading to Alan's most elegant equa- tion (still for a single cord) in which a frictional element has been added:

     1P2 = 4 ArEGa    

       [1 - 4 r x] 
           3A

     (in which x is the depth of [axial] imbedment and is the coefficient of friction when the fiber is pulled out against a frictional surface)

     [and in which everything after "=" is rather hard to do on a primitive (Wang) word processor]

     The bottom line, and the significant value to be measured, Alan emphasized, is not the stresses in the shear joint but the energy required to take it apart.

     In a delightful encore, our speaker related some of his observations as a member of the commission which investigated the Challenger disaster. These left this listener with the conviction that NASA is a classic aging institution in the throes of institutional menopause -- for which neither estrogen nor testosterone are likely to be as helpful as cyanide.

     And if you've read this far, please don't forget to call.

Jack Gieck 
Secretary

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Akron Physics Club

Newsletter


Meeting Announcement: MONDAY, April 25, 1994 - TANGIER, 6:00 PM



Speaker for our April meeting will be DR. VERNON NEFF of Kent State University, who will speak to us on:

SOLID STATE CHEMISTRY

Please CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, April 21st (because I must call them in Friday morning). And please don't forget to cancel if you must. The club gets charged for no-shows.


Minutes, April 25, 1994

     Despite the cancellation of Dr. Vernon Neff for our April meeting, pinch-hitter Jack Gieck was flattered by the attendance of Mark Dannis, Dan Galehouse, Alan Gent, Bob Harrington, Bob Hirst, John Liska, Dan Livingston, Leon Marker, Darrell Reneker, Jack Strang, Ernst von Meerwall, Charlie Wilson, Don Wiff and his guest, Jim Roach of GenCorp.

     Your secretary presented 30-year-old data, replete with genuine lantern slides, together with ultra-slow motion pictures that were the subject of his 1965 SAE paper studying the causes of brake noise, and, more generally, of the nature of squeaks. They are obviously created by, as Ernst von Meerwall put it better than the speaker, "a relaxation oscillator weakly coupled to a strong-willed resonator." [I've always suspected that Viennese were secretly taught English as their first language, since Austria, a linguistically challenged country, has no language of its own.]

     Squeaks appear to be a "slip-stick" phenomenon all right, but with the slip entirely in the reverse direction. The "stationary" components of brakes (rotor and lining puck; or backing plate, shoes and lining) always oscillate slightly about the torsion spring formed by the axle (or, in this case, the dynamometer shaft) at their natural frequency until the slowing drum or rotor comes close to matching their "forward" movement -- at which point (static friction being greater than dynamic friction) they lock together once per cycle, greatly increasing the amplitude of the resonator. Compressing the static and sliding coefficients of friction closer together, as with a lubricant, eliminates the squeak.

     Members who encouraged the speaker to investigate whether bowing a violin string is a variation of the same mechanism will be cheered to hear that he has acquired an ancient but runnable 11,000 frame-per-second camera, and has calibrated his C-mount lenses and extension tubes to be produce a field about 8mm wide (at a cost of two f-stops). The challenge will be to light the interface between the bow and the string at such infinitesimal exposure times without burning up bridge of the violin.

     You will see the results.

     To be continued.

     Once again, if you've read this far, please don't forget to call.

Jack Gieck
Secretary

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Akron Physics Club

Newsletter


Meeting Announcement: MONDAY, May 23, 1994 - TANGIER, 6:00 PM



Speaker for our May meeting will be our own DR. GEORG BOHM, Bridgestone/Firestone's Director of Research (who earlier headed research for a joint venture between Firestone and Radiation Dynamics, and who, in a previous life, taught at Max Planck Institute and in the Far East for the International Atomic Energy Institute). Georg's topic will be:

RADIATION EFFECTS ON POLYMERS AND APPLICATIONS THEREOF

Please CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, May 19th (because I must call them in Friday morning). And please don't forget to cancel if you must. The club gets charged for no-shows.


Minutes, May 23, 1994

     Near record attendance at our concluding spring meeting ( that included Mark Dannis, Dan Galehouse, Jack Gieck, Bob Hirst, John Liska, Dan Livingston, Leon Marker, Pad Pillai, Irv Prettyman, Darrell Reneker, Jack Strang, Ernst von Meerwall, Don Wiff, and Charlie Wilson) was, no doubt, attracted by our speaker, Georg Bohm, now Director of Bridgestone/Firestone Research, who spoke on RADIATION EFFECTS ON POLYMERS AND APPLICATIONS THEREOF.

     Radiation technology, Georg explained, goes back to the 1950s, and by the 1970s had become a billion dollar industry -- irradiated polyethylene being the first big one. The primary effects of electron radiation (which occurs in all of 10-9 seconds) vary with the energy of the accelerator. But, even at 3 KeV, these effects are orders of magnitude less than those of alpha radiation. It is one of the secondary effects of electron radiation, free radical reactions, which result in the cross-linking, that has led to nearly all commercial applications. But since high-energy radiation tends to kill things, other applications include medical equipment sterilization, food preservation, etc. And, of course, radiation continues to be a research tool. Radio-luminescence turns out to be particularly useful in polymer research.

     Georg gave us a list of polymers whose macromolecules tend to cross- link when irradiated, as well as those which are degraded by resulting scission. Indeed, both reactions often occur in the same material, and it is the ratio of cross-linking to scission that determines the properties of the irradiated product. Workers in the field have learned to control these things -- reducing breakup and the production of hydrogen by reducing energy transfer (by mixing into an aliphatic material, for example, small amounts of an aromatic e.g. benzene).

     Resulting commercial applications include heat-shrinkable polymer films, hydrogels, means to initiate polymerization as well as grafting onto substrates. And then there is the practically instantaneous vulcanization of elastomers at room temperature or even much lower. Unfortunately, the properties of radiation-cured elastomers are generally lower than those of rubbers cured with sulfur and heat (although their fatigue life is frequently better). Non-uniform properties throughout the material are due in part to the presence of traditional compounding additives -- even particles of carbon black, in whose vicinity properties degrade. But a number of rubber companies use radiation for precure -- to improve green strength, for example.

     Controlling the energy and selective sweep of the electron beam (producing a depth of cross-linking of about 4 mm per 100 KeV) permits a variety of creative product tricks that can be achieved on a continuous conveyorized setup in a matter of seconds. Wire insulation is a typical one.

     Although radiation is an interesting technology, it has not produced the product revolution expected by its promoters (e.g. radiation equipment manufacturers) and enthusiasts of two decades ago.

     CALL ME!

Jack Gieck
Secretary

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Akron Physics Club

Newsletter


Meeting Announcement: MONDAY, September 26, 1994 - TANGIER, 6:00 PM



Speaker for our first meeting of the new year will be our own ERNST VON MEERWALL, whose topic will be

USING NMR FOR (1) IMAGING AND (2) FOR VELOCITY MEASUREMENTS

And now for the drill: Please CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, April 21st (because I must call them in Friday morning). And please don't forget to cancel if you must. The club gets charged for no-shows.


Minutes, September 26, 1994
  

     Our first meeting of the new, vernal equinocal season again generated near record attendance, including Aggie Aggarwal, Mark Dannis, Tom Dukek, Dan Galehouse, Alan Gent, Jack Gieck, Bob Hirst, John Liska, Leon Marker, Pad Pillai, Irv Prettyman, Jack Strang, Charlie Wilson, and our speaker for the evening, Ernst von Meerwall.

     When Chairman Charlie Wilson called on Treasurer Dan Galehouse, our money person reported that there will be no need in the short term for a dues payment, since the treasury had a grand balance of $124.67 before the meeting -- subsequently augmented by an anonymous gift of $10.00 by someone whose serially-numbered ten-dollar bills had apparently stuck together.

     Program Chairman Leon Marker gave us a preview of things to come, including KSU mathematician Jerry Potter, speaking on artificial intelligence (e.g. expert systems) in February, and GENCORP's Jim Beecher, whose topic in March will be ESCA.

     Mark Dannis gave us both some old news and some new news about Jupiter and its recent confrontation with fragments of an errant comet.

     Our speaker, renaissance physicist Ernst von Meerwall demonstrated how, with relatively modest ("humble, obsolete") NMR equipment ("a magnet, plus a radio transmitter and a receiver"), in combination with innovative software (which like most inventions, seems to owe some of its inspiration to prior art -- in this case CATscan technology) and nearly two decades of dogged experimentation, can generate not only very acceptable photomicrographic images, but can also measure diffusion rates, flow characteristics, and the relative Newtonianism of such diverse fluids as water, polybutadiene, and a slurry of polybutadiene and sand.**

     Briefly presenting a plethora of equations dealing with such arcanities as spin echo characteristics when operating off resonance, not to mention other concepts that tended to overheat the neurons of this amateur (my mind developed its own "problem of the penumbra"), Ernst showed how he was able to dump dozens of projections into his computer, building up megabytes of information, to create simulations that he then compared with empirical reality.

     Water, happily, turns to be a classic Newtonian fluid, while polybutadiene is a shear-thinning, non-Newtonian fluid (since Ernst's sample was 100% butadiene, dilution was not a factor). His PBD-SiO2 slurry developed a "dizzy dance" with at least three degrees of freedom, that, our speaker observed, was not unlike the turbulence of diffusion.

     Ernst's presentation was a mind-expanding experience, habit-forming if your name happens to be von Meerwall, Wilson, or Hirst, for example(s).

     * NOW, THEN: You know the drill. Please CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, October 20 (not April 21), because I must call them in Friday morning.

Jack Gieck 
Secretary

** [1st prize for diagramming this sentence:  You get to be secretary!]

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Akron Physics Club

Newsletter


Meeting Announcement: MONDAY, October 24, 1994 - TANGIER, 6:00 PM



Dr. Donald Palmer

JOURNEY TO THE CENTER OF THE EARTH:

THE EARTH'S INTERIOR, AND HOW ONE GETS INFORMATION ABOUT IT*


Minutes, October 24, 1994

     In a beautifully orchestrated presentation invoking, for openers, the likes of Jules Verne, Sir Humphrey Davy, and an arrogant Dr. Mandrel of the Royal College of Surgeons (who, like Verne, pontificated that there were cavernous subterranean passageways leading a thousand miles into the earth), Dr. Donald Palmer led us on a captivating Journey to the Center of the Earth -- literally.

     His excellent slides portrayed a dense, thousand-kilometer-radius solid core surrounded by a molten liquid outer core, enveloped by a mantle, surmounted by the earth's crust. The continental crust, with an average specific gravity of 2.9, naturally floats on top of a sphere having an average density of 5.5. Ocean beds turn out to be a little denser. This distribution of mass has been inferred from such arcane clues as the moment of inertia of the body and the observation of seismic "shadows" as compressive shock waves travel through our sphere at some 6-8 km/second.

     We learned how the picture of the earth changed radically after 1896 with the discovery of radioactive heat sources; and in the last 25 years a cooperative seismic network has given rise to plate tectonics theory. Modern knowledge of earthquakes reveals that the deepest ones are about 700 km down, our speaker explained, but most are in the 400-600 km range.

     Don showed us how experimentally produced seismic waves (usually explosions produced with oil driller money) have profiled the layering of the ocean floor, have revealed the character of some five types of plate boundaries, and the occasional subduction of one plate diving under another with dramatic geographic consequences over the years.

     We were treated to fascinating maps of gravity highs and lows which often are congruent with magnetic highs and lows, indicating old continental tear-up zones billions of years old. We saw vertical cross sections of such discontinuities in nearby Kentucky and Tennessee -- one of which looks like it could be an image of a huge meteoric impact. The sensitivity of modern gravimeters producing this data, Don explained, could readily measure the difference in altitude from the lid of a coffee pot to the table top on which its base rests.

     An index of the group's interest was the number of times the speaker was interrupted with questions.

NOW THEN -- ONE LAST TIME FOR 1994:

     To simplify your secretary's life for our last meeting of the year [you were great last month, thank you!], please CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, November 24th, because I must call them in Friday morning.

Jack Gieck 
Secretary

* Thursday is THANKSGIVING! Can you please call by Wednesday, November 23rd??

 

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Akron Physics Club

Newsletter


Meeting Announcement: MONDAY, November 28, 1994 - TANGIER, 6:00 PM



Speaker for our November meeting will be DR. PETER RENALDI, Professor of Chemistry and Director of the University of Akron's Molecular Spectroscopy Laboratory, whose topic will be:

CAPABILITIES OF MODERN NMR SPECTROSCOPY

But our spies report that his talk might carry the subtitle,

"How to Make Modern Instruments Do
What Broken Instruments Did in the 1970s!" 


Minutes, November 28, 1994

     In attendance to hear Dr. Peter Rinaldi [whose name we have been consistently spelling wrong -- even on Tangier's lighted sign!], Director of the University of Akron's Molecular Spectroscopy Laboratory, were Georg Bohm, Mark Dannis, Tom Dukek, Dan Galehouse, Jack Gieck, Bob Hirst, Leon Marker, Dan Livingston, Pad Pillai, Irv Prettyman, Darrell Reneker, Jack Strang, Ernst von Meerwall and Charlie Wilson.

     Dr. Rinaldi, whose career spans both industry and academe, conducted a us on a tour of state-of-the-art nuclear magnetic resonance technology, emphasizing NMR's usefulness in determining the shape of molecules, the structure and connectivity of atoms, especially in organic polymers, and the dymanics of what is happening in such molecules. Since most elements have at least one isotope that can be detected by NMR, selectively seeding a molecule with these tracers produces groups of resonances that show up as peaks in the graphics produced when the sample is spun and excited.

     Title: Capabilities of NMR Spectroscopy.

     We were treated to several COSY (correlation spectroscopy) graphics, which combine two sets of wave forms, produced by applying pulses to two kinds (or subspecies) of nuclei simultaneously, in a two-dimensional contour plot. The off-diagonal regions of such plots are of special importance, revealing how each portion of a molecule interacts with its neighbors, and are useful in studying how block copolymers, for example, are hooked up.

     The sensitivity and signal-to-noise ratio of NMR has improved dramatically since 1958, when s/n ratios at 40-60 Mz were of the order of 2:1 or 3:1. They have actually been soaring by an order of magnitude per decade. Today, with a 750 Mz system, 20,000:1 is achievable. The signal to noise ratio, as Ernst von Meerwall points out, has risen as the 3.3 power of the resonant frequency.

     Modern systems, e.g. one in Peter Rinaldi's laboratory continuously circulates some 110 amperes through 40 Km of superconductive wire, developing 140,000 Gauss in the lab's double-chilled (liquid He inside liquid N2) supermagnet -- which is sufficient to snatch a steel tank out of a student's hands five feet away! But even this behemoth pales beside cutting-edge equipment which, at 600 Mz, induces 250-300,000 Gauss. Either of these systems concentrates 3 kilowatts of radio-frequency power in a one cubic center sample spun (at the magic 54o 44' angle) at 1-2 million rpm. The resulting heat is carried off by the same air that spins the sample. Dr. Rinaldi hopes to equip the University's laboratory with a 750 Mz unit within a few a few years.

     Treasurer [a thankless but essential job, as John Liska can testify; banks won't even take our paltry account] Dan Galehouse reported that the Society remains solvent. No dues duns for the present. Those of us who tried it once are grateful for Dan's dedicated service.

     Now, once again, BACK TO THE DRILL: Please CALL ME with either your RESERVATIONS OR REGRETS (867-2116) no later than Thursday afternoon, January 19th, since I must call them in Friday morning.

Jack Gieck*
Secretary

* With thanks to Ernst for leading the writer through the NMR wilderness (once again!)