This week, I returned from the his­toric 50^th Sani­bel Sym­po­sium. Over 350 chemists and physi­cists gath­ered together to cel­e­brate half-centennial suc­cess of quan­tum and com­pu­ta­tional chem­istry. One lec­ture that caught my atten­tion was a ple­nary talk “Con­duct­ing Poly­mers: a saga of more than 50 years” by pro­fes­sor Jean-Marie Andre. Pro­fes­sor Andre empha­sized a role of the­ory in describ­ing the phe­nom­ena of poly­mer con­duc­tiv­ity. The role, unfor­tu­nately, was never prop­erly acknowl­edged… In fact, con­duct­ing poly­mers were prac­ti­cally pre­dicted in 1962 by John Pople and S.H. Walm­s­ley [1] a long before their exper­i­men­tal discovery.

In this clas­si­cal paper Pople and Walm­s­ley intro­duced con­cept of soli­tons in poly­acety­lene. The neu­tral soli­ton is a rad­i­cal mis­fit which exists in the mid­dle of a long poly­ene chain con­tain­ing an odd num­ber of con­ju­gated car­bons and which con­sists of sev­eral suc­ces­sive bonds of sim­i­lar lengths near which the unpaired elec­tron is local­ized. Authors sug­gested that such a defect could be mobile and, if charged, could be respon­si­ble of an high elec­tri­cal con­duc­tiv­ity. Con­tinue reading →

6th March, 2010 3153 Commentshttp://www.isayev.info/from-conducting-polimers-to-first-organic-superconductors/From+Conducting+Polimers+to+First+Organic+Superconductors2010-03-06+22%3A33%3A38Olexandr+Isayev

PhD Comics, didn’t include DOIs in their recent bib­li­og­ra­phy of Christmas-related cita­tions. For lazy peo­ple, com­piled list is below:

• Christ­mas Dis­ease. Biggs, R, Dou­glas, A, Mac­far­lane, R, Dacie, J, Pit­ney, W, Merskey, C & O’Brien, J, 1952, BMJ, vol. 2, no. 4799, pp. 1378 – 1382.
  DOI: http://dx.doi.org/10.1136/bmj.2.4799.1378

Con­tinue reading →

29th December, 2009 Comments Off

The Brookhaven team, has been refin­ing tech­niques to use strands of arti­fi­cial DNA as a highly spe­cific kind of Vel­cro or glue to link up nanopar­ti­cles. Such DNA-based self-assembly holds promise for the ratio­nal design of a range of new mate­ri­als for appli­ca­tions in mol­e­c­u­lar sep­a­ra­tion, elec­tron­ics, energy con­ver­sion, and other fields. But none of these struc­tures has had the abil­ity to change in a pro­gram­ma­ble man­ner in response to mol­e­c­u­lar stim­uli — until now. “Now we’re using a spe­cial type of DNA-linking device — a kind of ‘smart glue’ — that affects how the par­ti­cles con­nect to make struc­tures that are switch­able between dif­fer­ent con­fig­u­ra­tions,” says Oleg Gang a team lead. This reli­able, reversible switch­ing could be used to reg­u­late func­tional prop­er­ties — for exam­ple, a material’s flu­o­res­cence and energy trans­fer prop­er­ties — to make new mate­ri­als that are respon­sive to chang­ing con­di­tions, or to alter their func­tions on demand.

a) Ide­al­ized schematic illus­trat­ing the struc­ture of the device (l_d) link­age, with A’, D’ and B’ recog­ni­tion sequences. b) A bcc unit cell rep­re­sen­ta­tion of a bulk three-dimensional super­lat­tice con­sist­ing of nanopar­ti­cles A – p and B – p inter­con­nected by l_d. © Nature Pub­lish­ing Group.

Con­tinue reading →

22nd December, 2009 Comments Off

Tip #1: Walk fast when on cam­pus and explain to col­leagues that you can­not go out to lunch because you are busy respond­ing to law review edi­tors’ com­ments on your manuscript.

Tip #2: Remind your col­leagues how many stu­dents you teach, how many exams you have to grade, how fright­fully many hours it will take you to grade them, and how grad­ing exams really cuts down the time you can be avail­able for schol­ar­ship, ser­vice activ­i­ties, friends or family.

Tip #3: Send an e-mail inform­ing your dean or col­leagues that you have been invited to speak at the local Rotary Club or the neigh­bor­ing town’s PTA meeting.

Tip #4: Bring mas­sive amounts of work to talks by out­siders and stu­dent events, and make sure to vis­i­bly mark on doc­u­ments — as if edit­ing your own paper or mak­ing com­ments on stu­dent work — in full sight of every­one else in the room.

Tip #5: Get ticked off and behave badly at fac­ulty meetings.

Tip #6: Do not timely answer e-mails from any­one who may be rely­ing on you to show up to an event, help review appli­ca­tions or sched­ule a meet­ing, then get huffy when the meet­ing takes place before you respond to the e-mail.

[via The Chron­i­cle ]

6th December, 2009 Comments Off

IBM’s Almaden Research Cen­ter announced in Novem­ber that it had pro­duced a “cor­ti­cal sim­u­la­tion” of the scale and com­plex­ity of a cat brain. This sim­u­la­tion ran on one of IBM’s Blue Gene super­com­put­ers, in this case at the Lawrence Liv­er­more National Lab­o­ra­tory (LLNL):

Sci­en­tists, at IBM Research — Almaden, in col­lab­o­ra­tion with col­leagues from Lawrence Berke­ley National Lab, have per­formed the first near real-time cor­ti­cal sim­u­la­tion of the brain that exceeds the scale of a cat cor­tex and con­tains 1 bil­lion spik­ing neu­rons and 10 tril­lion indi­vid­ual learn­ing synapses.

The fig­ure presents the results of our weak scal­ing study, where the prob­lem size is increased with increas­ing amount of mem­ory. The plot demon­strates nearly per­fect weak scal­ing in terms of mem­ory, since twice the model size could be sim­u­lated when the amount of mem­ory is dou­bled. The largest sim­u­lated model cor­re­sponds to a scale larger than the cat cere­bral cor­tex, reach­ing 4.5% of the human cere­bral cor­tex.

Scal­ing of Cor­ti­cal Sim­u­la­tions. Copy­right © 2009, ACM, Inc.

2nd December, 2009 2451 Commenthttp://www.isayev.info/simulation-a-cat-like-brain/Simulation+a+Cat-Like+Brain2009-12-02+19%3A28%3A41Olexandr+Isayev