Archive for the ‘Chemistry’ Category

Columbia University maintains a wall of silence around the Sezen – Sames case

August 15, 2011

The Bengü Sezen – Dalibor Sames scandal rumbles on while Columbia maintains a wall of silence around the case. But the silence raises suspicions. Sezen has been painted as and has appeared clearly as the villain in the piece but Dalibor Sames  – her supervisor – seems to be getting away with very little censure. What is especially disturbing is that three of his subordinates lost their positions for raising doubts about her work while he was rewarded with tenure during the same period. To that extent it does seem that some of the extreme rhetoric now being used against Sezen and the scathing “official” criticism of Sezen is “designed” – at least partially – to deflect questions and blame away from Sames. It seems inexplicable to me that Dalibor Sames can escape any responsibility or censure and is not to be held accountable for his part in the affaire. To take away his tenure would of course be an unacceptable precedent for Columbia and would be quite unthinkable! But even assuming – in the best case – that he had no part in the deception he does come across as being not only incompetent to supervise research by others but also as eminently gullible. In the worst case he could have been her Svengali.

Chemical & Engineering News carries a new comprehensive article by William Schulz about the case and Rudy Baum posts about Sezen, Sames and Columbia  in the Editors blog.

This week’s lead Science & Technology Department story by C&EN News Editor William G. Schulz is a devastating account of systematic scientific fraud committed by former Columbia University chemistry graduate student Bengü Sezen. Schulz has been following the Sezen case since her work was called into question and Columbia began an investigation of it in 2006.

Sezen worked under the direction of Dalibor Sames from 2000 to 2005. Sames was an assistant chemistry professor when Sezen joined his group; he received tenure at Columbia in 2003. During her time in Sames’ lab, Sezen was the lead author on three papers published in the Journal of the American Chemical Society, all of which Sames retracted in 2006 after the results reported in the papers were called into question because no one could reproduce them (J. Am. Chem. Soc. 2006, 128, 8364). Sezen received her Ph.D. in 2005; Columbia revoked it earlier this year. …

But what of Sames? Questions about Sezen’s research were raised by other members of Sames’ group as early as 2002, Schulz reports. Those questions weren’t just ignored by Sames; those who raised them were punished. “At least three unnamed subordinates left or were dismissed from the Sames lab, for example, for stepping forward and raising concerns about Sezen’s irreproducible research results,” Schulz writes. As the report makes clear, these whistle-blowers were sacrificed in order to maintain her favored status in the research group. Sames acted, in fact, only after a member of his group specifically set Sezen up and presented irrefutable evidence of her misconduct.

Columbia’s investigation focused exclusively on Sezen’s misconduct.  From the ORI report obtained by C&EN, it appears that Columbia has not made any attempt to probe whether Sames was guilty of scientific misconduct himself during Sezen’s time in his lab. 

Schulz writes in his excellent article:

Questions about the massive Bengü Sezen scientific fraud case at Columbia University linger in the August heat. But many of them will likely never be answered—especially the question, Why? Columbia in 2005 awarded her a Ph.D. degree in chemistry with distinction; however, it was based in large part on her fraudulent work. Details of the case make clear that Sezen, at the very least, has a sophisticated understanding of chemical principles. The effort she put into faking it and covering her tracks, say many people who have reviewed the case, easily match that required for legitimate doctoral work in science……. Sezen left Columbia shortly after receiving her chemistry degree and enrolled at Germany’s Heidelberg University, where she picked up another doctoral degree in molecular biology. But, with mounting questions about her chemistry thesis and published work—eventually to include retraction of research papers she coauthored with her professor, Dalibor Sames, on C–H bond functionalization—Columbia assembled an investigative committee to probe deeper. ….

As the evidence of her misconduct began to pile up, however, her attempts to explain away her actions became increasingly implausible. …. And then she was gone. Sezen’s whereabouts today are unknown. ……..

Columbia has erected a wall of silence around Sezen, her brazen fakery, and the consequences for those who had the misfortune of working with her. Aside from the few spare and prepared statements about her doctoral degree and the status of its misconduct investigation, the university has blotted out any mention of what happened inside the Sames laboratory between 2000 and 2005, when Sezen was a Ph.D. candidate. During this period, however, Sames was granted tenure.

Columbia has expressly forbidden Sames or any of its other employees from speaking publicly about the Sezen case. ……..

But it’s unclear what, if any, consequences Sames has suffered because of his failure to find out what might be going on with Sezen, especially when red flags about her work were raised so early on. A visit to the Sames group website today includes a photo of Sames and a slideshow of many young, enthusiastic, and smiling lab group members.

From the comments on the blog ChemBark it would seem that one of the commenters is Sezen herself and that she is still in Germany (or operating through an IP address from Germany). 

Related: The Sezen Files: Part1, Part2 and Part3

The ultimate element anagram

June 11, 2011

The periodic table of elements – first put together by Mendeleev in 1869 –  sometimes seems to have almost mystical properties

Mendeleev's 1869 periodic table; note that his arrangement presents the periods vertically, and the groups horizontally: wikipedia

From Slate

But for my money, the all-time greatest wordplay related to the periodic table is this “doubly true” anagram, which won Mike Keith the special category prize in May 1999 at Anagrammy.com. The initial anagram equates thirty elements on the periodic table with 30 other elements:

hydrogen + zirconium + tin + oxygen + rhenium + platinum + tellurium + terbium + nobelium + chromium + iron + cobalt + carbon + aluminum + ruthenium + silicon + ytterbium + hafnium + sodium + selenium + cerium + manganese + osmium + uranium + nickel + praseodymium + erbium + vanadium + thallium + plutonium

=

nitrogen + zinc + rhodium + helium + argon + neptunium + beryllium + bromine + lutetium + boron + calcium + thorium + niobium + lanthanum + mercury + fluorine + bismuth + actinium + silver + cesium + neodymium + magnesium + xenon + samarium + scandium + europium + berkelium + palladium + antimony + thulium

That’s more than half the periodic table—pretty amazing, especially since he used the elements with Xs and Zs. The kicker is that if you replace each element with its number on the periodic table, the anagram still balances:

1 + 40 + 50 + 8 + 75 + 78 + 52 + 65 + 102 + 24 + 26 + 27 + 6 + 13 + 44 + 14 + 70 + 72 + 11 + 34 + 58 + 25 + 76 + 92 + 28 + 59 + 68 + 23 + 81 + 94

=

7 + 30 + 45 + 2 + 18 + 93 + 4 + 35 + 71 + 5 + 20 + 90 + 41 + 57 + 80 + 9 + 83 + 89 + 47 + 55 + 60 + 12 + 54 + 62 + 21 + 63 + 97 + 46 + 51 + 69

= 1416

Ununquadium = Flerovium and Ununhexium = Moscovium?

June 9, 2011

In June last year it was reported that element 114 – with the temporary name ununquadium – had been manufactured in the lab.

Periodic table gets bigger: Element 114 Ununquadium

Now a a joint working party of the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP) have concluded that elements 114 and 116 have fulfilled criteria for official inclusion in the periodic table.

Discovery of the elements with atomic numbers greater than or equal to 113

doi:10.1351/PAC-REP-10-05-01

Abstract: The IUPAC/IUPAP Joint Working Party (JWP) on the priority of claims to the discovery of new elements 113–116 and 118 has reviewed the relevant literature pertaining to several claims. In accordance with the criteria for the discovery of elements previously established by the 1992 IUPAC/IUPAP Transfermium Working Group (TWG), and reinforced in subsequent IUPAC/IUPAP JWP discussions, it was determined that the Dubna-Livermore collaborations share in the fulfillment of those criteria both for elements Z = 114 and 116. A synopsis of experiments and related efforts is presented.

The discovery of both elements has been credited to a collaborative team based at the Joint Institute for Nuclear Research in Dubna, Russia, and Lawrence Livermore National Laboratory in California, US. The collaborative parties have proposed the name flerovium for 114, after Soviet scientist Georgy Flyorov, and moscovium for 116, after the region in Russia.

In recent years, there have been several claims by laboratories for the discovery of elements at 113, 114, 115, 116 and 118 in the periodic table. The working party concluded that elements 114 and 116 now fulfilled criteria for official inclusion in the table.

Periodic Table

Periodic Table with the Unun series: image BBC

The two new elements are radioactive and only exist for less than a second before decaying into lighter atoms. Element 116 will quickly decay into 114, and 114 transforms into the slightly lighter copernicium as it sheds its alpha particles.

A metallic glass tougher than steel

January 11, 2011

An exciting new paper in materials technology

A damage-tolerant glass by Marios D. Demetriou, Maximilien E. Launey, Glenn Garrett, Joseph P. Schramm, Douglas C. Hofmann, William L. Johnson & Robert O. Ritchie

Nature Materials (2011) doi:10.1038/nmat2930
From EurekAlert:

A new type of damage-tolerant metallic glass, demonstrating a strength and toughness beyond that of any known material, has been developed and tested by a collaboration of researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab)and the California Institute of Technology. What’s more, even better versions of this new glass may be on the way. The new metallic glass is a microalloy featuring palladium, a metal with a high “bulk-to-shear” stiffness ratio that counteracts the intrinsic brittleness of glassy materials.

Glassy materials have a non-crystalline, amorphous structure that make them inherently strong but invariably brittle. Whereas the crystalline structure of metals can provide microstructural obstacles (inclusions, grain boundaries, etc.,) that inhibit cracks from propagating, there’s nothing in the amorphous structure of a glass to stop crack propagation. The problem is especially acute in metallic glasses, where single shear bands can form and extend throughout the material leading to catastrophic failures at vanishingly small strains.

In earlier work, the Berkeley-Cal Tech collaboration fabricated a metallic glass, dubbed “DH3,” in which the propagation of cracks was blocked by the introduction of a second, crystalline phase of the metal. This crystalline phase, which took the form of dendritic patterns permeating the amorphous structure of the glass, erected microstructural barriers to prevent an opened crack from spreading. In this new work, the collaboration has produced a pure glass material whose unique chemical composition acts to promote extensive plasticity through the formation of multiple shear bands before the bands turn into cracks.

“Our game now is to try and extend this approach of inducing extensive plasticity prior to fracture to other metallic glasses through changes in composition,” Ritchie says. “The addition of the palladium provides our amorphous material with an unusual capacity for extensive plastic shielding ahead of an opening crack. This promotes a fracture toughness comparable to those of the toughest materials known. The rare combination of toughness and strength, or damage tolerance, extends beyond the benchmark ranges established by the toughest and strongest materials known.”

The initial samples of the new metallic glass were microalloys of palladium with phosphorous, silicon and germanium that yielded glass rods approximately one millimeter in diameter. Adding silver to the mix enabled the Cal Tech researchers to expand the thickness of the glass rods to six millimeters. The size of the metallic glass is limited by the need to rapidly cool or “quench” the liquid metals for the final amorphous structure.

“The rule of thumb is that to make a metallic glass we need to have at least five elements so that when we quench the material, it doesn’t know what crystal structure to form and defaults to amorphous,” Ritchie says.

The new metallic glass was fabricated by co-author Demetriou at Cal Tech in the laboratory of co-author Johnson. Characterization and testing was done at Berkeley Lab by Ritchie’s group.

Ozone layer hits record thickness in Sweden: Was there ever an ozone hole problem?

January 9, 2011

Lately there has been an increasing view that some of the catastrophe scenarios about the ozone hole which led to the Montreal Protocol of 1989 were exagerrated and based on poor science. The effects of humans on ozone variations as opposed to natural variations may have been exaggerated. In fact there are now some suggestions that the actions taken were not only unnecessary but that they have not had much to do with the natural increase of ozone layer thickness observed in recent times.

The Local reports:

Sweden’s government weather agency reported on Friday that the ozone layer over southern Sweden reached its thickest levels at the end of last year, surpassing the previous record set in 1991.

Sweden’s Meteorological and Hydrological Institute (Sveriges Meteorologiska och Hydrologiska Institut, SMHI) explained that the weather was particularly favourable at the end of 2010 and it explain why the ozone layer was especially thick at the time. “It is a step in the right direction, but it is still too early to say that the ozone layer has recovered. The favourable weather situation over the last few months has contributed to a record high,” said Weine Josefsson, a meteorologist at SMHI, in a statement on Friday.
The annual value of the ozone layer’s thickness over Norrköping in 2010 stood at a new high of 351.7 Dobson units (DU). The previous record was set in 1991 at 341.8 DU. The November and December values in particular set new records among the measurements regularly made at SMHI since 1988. ……….  Even in Norrland in the country’s north, the values have been positive in the last year. The ozone layer has been measured regularly in Vindeln northwest of Umeå in northern Sweden since 1991 and the latest results were also positive in this area.
However, it is not possible to record complete ozone measurements in the winter, so it is uncertain whether a record was set there as well at the end of last year. In November and December, air flows were affected by a special weather situation over western Europe, resulting in an extra thick ozone layer over this part of the world in these two months.
It is possible that the restrictions on ozone-depleting substances proposed in the Montreal Protocol in 1987 have also contributed to the thickening of the ozone layer. However, this type of measure is effective over a long period of time and it is difficult to distinguish the effect of natural variations in this case.

Chemistry unsettled

December 16, 2010
International Year of Chemistry Logo

Image via Wikipedia

Atomic weights of 10 elements on periodic table about to make an historic change

For the first time in history, a change will be made to the atomic weights of some elements listed on the Periodic table of the chemical elements posted on walls of chemistry classrooms and on the inside covers of chemistry textbooks worldwide.

The new table, outlined in a report released this month, will express atomic weights of 10 elements – hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine and thallium – in a new manner that will reflect more accurately how these elements are found in nature.

“For more than a century and a half, many were taught to use standard atomic weights — a single value — found on the inside cover of chemistry textbooks and on the periodic table of the elements. As technology improved, we have discovered that the numbers on our chart are not as static as we have previously believed,” says Dr. Michael Wieser, an associate professor at the University of Calgary, who serves as secretary of the International Union of Pure and Applied Chemistry‘s (IUPAC) Commission on Isotopic Abundances and Atomic Weights. This organization oversees the evaluation and dissemination of atomic-weight values.

Modern analytical techniques can measure the atomic weight of many elements precisely, and these small variations in an element’s atomic weight are important in research and industry. For example, precise measurements of the abundances of isotopes of carbon can be used to determine purity and source of food, such as vanilla and honey. Isotopic measurements of nitrogen, chlorine and other elements are used for tracing pollutants in streams and groundwater. In sports doping investigations, performance-enhancing testosterone can be identified in the human body because the atomic weight of carbon in natural human testosterone is higher than that in pharmaceutical testosterone.

The atomic weights of these 10 elements now will be expressed as intervals, having upper and lower bounds, reflected to more accurately convey this variation in atomic weight. The changes to be made to the Table of Standard Atomic Weights have been published in Pure and Applied Chemistry and a companion article in Chemistry International.

For example, sulfur is commonly known to have a standard atomic weight of 32.065. However, its actual atomic weight can be anywhere between 32.059 and 32.076, depending on where the element is found. “In other words, knowing the atomic weight can be used to decode the origins and the history of a particular element in nature,” says Wieser who co-authored the report.

Elements with only one stable isotope do not exhibit variations in their atomic weights. For example, the standard atomic weights for fluorine, aluminum, sodium and gold are constant, and their values are known to better than six decimal places.

“Though this change offers significant benefits in the understanding of chemistry, one can imagine the challenge now to educators and students who will have to select a single value out of an interval when doing chemistry calculations,” says Dr. Fabienne Meyers, associate director of IUPAC.

http://www.eurekalert.org/pub_releases/2010-12/uoc-awo121510.php

Now fluorographene from Graphene Nobel winners

November 9, 2010

A new paper by the Graphene Nobel winners in the Journal Small:

Fluorographene: A Two-Dimensional Counterpart of Teflon, by Rahul R. Nair, Wencai Ren, Rashid Jalil, Ibtsam Riaz, Vasyl G. Kravets, Liam Britnell, Peter Blake, Fredrik Schedin, Alexander S. Mayorov, Shengjun Yuan, Mikhail I. Katsnelson, Hui-Ming Cheng, Wlodek Strupinski, Lyubov G. Bulusheva, Alexander V. Okotrub, Irina V. Grigorieva, Alexander N. Grigorenko, Kostya S. Novoselov, Andre K. Geim. Article first published online: 4 NOV 2010, DOI: 10.1002/smll.201001555

Abstract

A stoichiometric derivative of graphene with a fluorine atom attached to each carbon is reported. Raman, optical, structural, micromechanical, and transport studies show that the material is qualitatively different from the known graphene-based nonstoichiometric derivatives. Fluorographene is a high-quality insulator (resistivity >1012Ω) with an optical gap of 3 eV. It inherits the mechanical strength of graphene, exhibiting a Young’s modulus of 100 N m−1 and sustaining strains of 15%. Fluorographene is inert and stable up to 400 °C even in air, similar to Teflon.

Graphane crystal. This novel two-dimensional material is obtained from graphene (a monolayer of carbon atoms) by attaching hydrogen atoms (red) to each carbon atoms (blue) in the crystal. (Credit: Mesoscopic Physics Group, Prof. Geim - University of Manchester)

Science Daily. University of Manchester scientists have created a new material which could replace or compete with Teflon in thousands of everyday applications. Professor Andre Geim, who along with his colleague Professor Kostya Novoselov won the 2010 Nobel Prize for graphene — the world’s thinnest material, has now modified it to make fluorographene — a one-molecule-thick material chemically similar to Teflon.

Fluorographene is fully-fluorinated graphene and is basically a two-dimensional version of Teflon, showing similar properties including chemical inertness and thermal stability. Teflon is a fully-fluorinated chain of carbon atoms. These long molecules bound together make the polymer material that is used in a variety of applications including non-sticky cooking pans. The Manchester team managed to attach fluorine to each carbon atom of graphene. To get fluorographene, the Manchester researchers first obtained graphene as individual crystals and then fluorinated it by using atomic fluorine. To demonstrate that it is possible to obtain fluorographene in industrial quantities, the researchers also fluorinated graphene powder and obtained fluorographene paper.

Fluorographene turned out to be a high-quality insulator which does not react with other chemicals and can sustain high temperatures even in air.

Industrial scale production of fluorographene is not seen as a problem as it would involve following the same steps as mass production of graphene. The Manchester researchers believe that the next important step is to make proof-of-concept devices and demonstrate various applications of fluorographene. Professor Geim added: “There is no point in using it just as a substitute for Teflon. The mix of the incredible properties of graphene and Teflon is so inviting that you do not need to stretch your imagination to think of applications for the two-dimensional Teflon. The challenge is to exploit this uniqueness.”

 

Graphene: Urban legend in the making?

October 8, 2010

As I posted earlier, the Nobel Prize in Physics 2010 was awarded jointly to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene”

It seems there is no controversy that “the first graphene samples formed were produced by pulling atom thick layers from a sample of graphite using sticky tape”.

But whether the graphite sample was actually lead flakes from a pencil and whether the sticky tape was actually Scotch tape is more uncertain. Nevertheless, it is now the stuff of urban legend and the subject of cartoons.

 

Nobel physics 2010.png

sticky tape + pencil = graphene

 

http://blogs.nature.com/strippedscience/2010/10/06/nobel-prize-in-physics-2010-catoon

Next week is Nobel week: My layman forecasts

October 1, 2010

This week I won a $10 prize in a lottery and my belief in my crystal ball is high (but I ignore the fact that the lottery tickets cost me $30).

Nobel Prize® medal - registered trademark of the Nobel Foundation

Nobel prize medal

Next week is Nobel week and the winners for Medicine will be announced on Monday 4th, for Physics on Tuesday 5th and for Chemistry on Wednesday 6th. I pass over the Literature, Economics and Peace prizes in silence but address my crystal ball as to the areas of research that will be honoured.

Medicine: The 2 areas that spring to mind are stem cells and genetic cancer research. To choose one I go for stem cells with Dr. Yamanaka included in there somewhere.

Physics: The 2 areas I see as most likely are either quantum physics or the expanding universe. To choose one I plump for the universe and Prof. Perlmutter among the recipients.

Chemistry: I am fascinated by new materials and with graphene being the flavour of the decade I choose work related to graphene as being the winner. To name a name it would be just if the first person to discover graphene received recognition and so I hope that Hanns-Peter Boehm is on the list.

In spite of my lottery win, I put the probability of being right on one count at no more than 1%, on two counts at 0.1% and being right on all 3 at 0.01%.

Add your favourites if you have any.