Nobel

�山ǿ�� chemists uncover a means to control catalytic reactions

ullahnor — Mon, 12 Dec 2016 20:14:34 +0000

�山ǿ�� chemists uncover a means to control catalytic reactions

ullahnor Mon, 12/12/2016 - 15:14

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From left to right, �山ǿ��'s Nobel Prize-winning chemist John Polanyi with PhD candidate Kelvin Anggara, research associate Lydie Leung and postdoctoral researcher Kai Huang (photo by Jaclyn Shapiro)

Sean Bettam

Author legacy

Sean Bettam

Topic

Breaking Research

Chemistry

John Polanyi

Nobel

Research & Innovation

Scientists at the University of Toronto have found a way to make catalysis – the use of catalysts to facilitate chemical reactions – more selective, breaking one chemical bond 100 times faster than another. The findings are described in a study published in Nature Communications.

The team of researchers led by Nobel Prize-winning chemist John Polanyi employed a combination of experiment and theory to discover that the position of the molecule on the catalytic surface is a key factor in determining the rate at which particular bonds break.

“We found that the microscopic positioning of the molecule relative to the catalytic surface below, rendered the catalyst highly bond-specific,” says Polanyi, university professor in the department of chemistry at �山ǿ��. “The closer the alignment of the bonds of the molecule to the rows of atoms in the catalyst, the more selective was the reaction.”

The scientists investigated a chemical reaction that involved breaking carbon-to-iodine bonds in the organic molecule iodobenzene by means of metallic copper, a common catalyst. The reaction was initiated by an electron coming from the tip of a microscope, which attached itself to the iodobenzene.

“We observed acceleration in the reactivity of the carbon-to-iodine bonds when those bonds were aligned along rows of copper atoms in the catalyst, as compared to the bonds aligned across the copper rows,” says Kelvin Anggara, a PhD candidate in Polanyi’s research group and a lead author of the study.

“The copper surface acted more strongly on bonds that were nearby than on bonds that were further away,” Anggara says. “We saw 100-fold differences in reactivity between bonds pointing in specific directions on the catalyst.”

The experiment could be explained by a mathematical model developed by the researchers over the past few years, which enabled them to produce a computer-generated movie of the motions of the atoms involved in the bond-breaking at the copper surface. It was the movie that revealed the reason why the copper catalyzed the bonds along its rows in preference to bonds across the rows.

“The copper atoms along the rows were slightly closer together by about the diameter of a single atom than the atoms across the rows,” says Anggara. “This closer spacing promoted the breaking of bonds lying along the rows.”

The method is rooted in the study of chemical reactions taking place at the surface of solid materials that has guided Polanyi and his colleagues for decades. Following his Nobel Prize in chemistry in 1986 for observing the molecular motions in chemical reactions occurring in gases, Polanyi began studying the reactions of individual molecules lying on well-defined catalytic surfaces.

Polanyi says scientists are only beginning to understand how catalysis operates, and that the shift towards green chemistry makes knowing as much as possible about catalysts and how they reduce waste caused by chemical reactions more important than ever before.

“The challenge for the future will be to fabricate metal catalysts embodying atomic patterns that speed chemical reactions along pathways that lead to desired products,” said Polanyi. “Recent advances in the construction of surfaces, atom-by-atom, lend themselves to the fabrication of such engineered-catalysts. We’re now a bit closer to that since we begin to understand what patterns of atoms make the best catalysts.”

The findings are reported in the study “Bond selectivity in electron-induced reaction due to directed recoil on an anisotropic substrate.”

Support for the research was provided by the Natural Sciences and Engineering Research Council of Canada, �山ǿ�� NSERC General Research Fund and the Connaught International Scholarship for Doctoral Studies. Computations were performed on the SciNet HPC Consortium supercomputer at �山ǿ��.

But is it literature? �山ǿ�� experts on Bob Dylan's Nobel Prize

lavende4 — Fri, 14 Oct 2016 15:35:14 +0000

But is it literature? �山ǿ�� experts on Bob Dylan's Nobel Prize

lavende4 Fri, 10/14/2016 - 11:35

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Bob Dylan performing at a musical festival in western France in 2012 (photo by Fred Tanneau/Getty images)

Arthur Kaptainis

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Arthur Kaptainis

Topic

The Swedish Academy stunned the world and delighted music enthusiasts of many generations on Thursday by awarding the Nobel Prize in Literature to celebrated singer-songwriter Bob Dylan.

The news is making headlines here at home and around the world. (Read �山ǿ��'s Ira Wells in The Globe and Mail and The National Post)

�山ǿ�� News spoke to Robin Elliott, professor of musicology and Jean A. Chalmers Chair in Canadian Music; Don McLean, professor and dean of the Faculty of Music; Ken McLeod, associate professor of music and culture at �山ǿ�� Scarborough; and Ira Wells, a sessional instructor in American literature in the department of English.

Is this a surprising award?

Ira Wells: It is rare for an American to win the Nobel Prize in Literature. The last was Toni Morrison in 1993. And obviously Dylan is the first pop singer. Many recent Nobel literature laureates have been niche figures, known only in literary circles. It is rare that you get a celebrity on these lists, especially someone of Dylan’s magnitude.

Ken McLeod: I think it’s wonderful that a singer-songwriter has been recognized for the quality and impact of lyrics. Going back to the ancient Greeks, the great narrative epics were accompanied and enhanced by music. The ability to write literature and/or poetry as an adjunct to music has been highly prized in classical music from the criticism of Robert Schumann, the narratives of Berlioz and, perhaps most prominently, in the works of Richard Wagner, who is celebrated for having written both the texts and music for his music dramas.

But do lyrics on their own count as literature?

Ira Wells: There is a relatively simple way of addressing that question. Do the lyrics yield multiple interpretations? Is it possible to read these lyrics and come up with multiple interpretations that would reward serious, close reading? That is a baseline for a university professor deciding whether or not something counts as literature. It is indisputably the case that Dylan’s best songs – "Like a Rolling Stone," "Visions of Johanna," "Every Grain of Sand" – meet this threshold.

Don McLean: Popular-music lyrics across a wide range of genres make up arguably the most significant poetic form of the 20th and early 21st centuries. Lieder and folksong-derived nationalisms of the long 19th century remained confined largely to arts-circle and upper-middle-class elites. Sound reproduction paved the way for the radio and record industries, without which the ubiquity of popular music is unthinkable. For many, American and British popular music became the iconic poetics and affective underpinning of the age, which is in part why relationships to music and artists are so nostalgia- and memory-driven.

Ken McLeod: In an age of – I would argue – declining emphasis on meaningful lyrical content in popular music, it is nice to see that indeed words can and do matter (with apologies to Donald Trump). Even though it is clear that many listeners mishear a large percentage of Dylan’s lyrics in his recordings (as indeed is the case for many pop music recordings).

There are many Dylans. Is he still equated substantially with the early protest songs?

Ira Wells: For many of his most ardent fans, Dylan has never really outgrown that phase of his career. "The Times They Are A-Changin" and "Blowin’ in the Wind": that is what Bob Dylan is. In fact, that protest period lasted only a few years. By the mid-1960s he had become something quite different. Bringing It All Back Home and Blonde on Blonde are more or less apolitical albums.

This is what is fascinating about Dylan as a cultural figure. He has changed so many times. And he has not only changed, he seems almost in a perverse way to react against the expectations and desires of his audience. Just when people are starting to celebrate him as a folk protest singer, he plugs in and becomes a rock 'n' roll star. Just when rock 'n' roll becomes culturally accepted in the late 1960s, he reinvents himself as a country song writer in Nashville Skyline. When we move into disco and punk in the late 1970s, Bob Dylan becomes a Christian gospel singer.

Is this contrarianism a literary quality?

Ira Wells: It certainly implies that he is not abiding by market imperatives. It suggests that there is something else going on. He is not responding to the marketplace as did the other well-known musical acts of his generation: The Rolling Stones, U2, Paul McCartney. Dylan rises above the marketplace. And he defies expectations in a manner that seems almost deliberately calibrated to alienate his fans. If you have ever seen him in concert, he almost never addresses the audience. He makes no attempt to entertain you. He does his thing, and you either get it or you don’t.

How will other musicians react to this?

Don McLean: Dylan was, and is, considered hugely influential by many contemporary and later musicians. I have heard this directly from Joni Mitchell and Patti Smith. The Beatles’s lyrics and generic mimicking were puerile until they started breathing at Dylan depth. These artists use song as the chariot of poetry. As with Dylan, the music bears the lyrics forward and gives them a halo of reflective complexity not always evident in the text itself.

Would it be valid to call Dylan a revolutionary?

Don McLean: The idea of “game changers” and stylistic “revolutionary steps forward” in popular music always seems improbable to classically-trained musicians, on harmonic grounds alone. But Bob Dylan’s lyrics, music and performances – "Like a Rolling Stone," "Mr. Tambourine Man," "Every Grain of Sand" – his folk-blasting electrification and his gravelly but never grovelling voice-of-God delivery have all given many cause for pause.

Does the Dylan victory give Canada hope for a Nobel? Or at least make it possible to view lyrics more critically?

Robin Elliott: Leonard Cohen would be the nearest Canadian equivalent to Bob Dylan. Both were poet-songwriters who negotiated the boundaries between folk and pop music while capturing the Zeitgeist of the 1960s and beyond. Both have received widespread acclaim and recognition for both their literary and musical activity over the past five decades and more.