Scientists from Harvard University and the Massachusetts Institute of Technology have developed a theoretical model of a material that one day could anchor the development of highly efficient solar panels.Traditional organic solar panels work by combining photons with light-sensitive materials, creating particles called excitons. Those particles are then channeled through the material to an interface, where they dump energy into electrons that flow along wires, producing electricity. The problem is that excitons aren’t easy to control. The particles are often trapped by defects in the material, and release their energy as light, reducing the efficiency of the panels.Inspired by cutting-edge theories in condensed matter physics and the development of quantum computers, the Harvard-MIT group used magnetic fields to force excitons to move in a specific direction, avoiding the traps that plague traditional materials. The system is described in a paper in Nature Materials.The research team was led by Professor of Chemistry and Chemical Biology Alan Aspuru-Guzik and included Joel Yuen-Zhou, a former Ph.D. student in Aspuru-Guzik’s lab who is now a postdoctoral fellow at MIT, and research associate Semion Saikin.“This effect has been identified in physics, in what’s called the quantum Hall effect, and in topological insulators, but we believe this is the first time this has been proposed in a practical way for excitons in molecular layers,” Aspuru-Guzik said. “What we wanted to ask was, can this be done in organic materials? Can you custom-tailor an organic material in such a way that, for certain excitation energies, excitons move in one direction, and when they confront obstacles, they can move around them?”Yuen-Zhou and Saikin began searching for molecules that fit a tightly defined set of criteria, and eventually settled on porphyrins, in part because they have been extensively studied.“These are just one example of a molecule that could work in this system,” said Saikin. “We don’t want to say that, experimentally, one has to do it with these molecules, but conceptually, we’ve shown that the electronic structure of these molecules is convenient for this system.”The system described in the paper, however, is about more than simply creating a film of porphyrin molecules.For the design to work, the team outlined how magnets could be used to prepare the molecules in specific quantum states to ensure they don’t interfere with one another.“In the absence of a magnetic field, it’s equally likely the excitons would go in one direction or another,” Aspuru-Guzik said. “We use some very clever quantum tricks, to ensure that, when we apply the field, one direction becomes more preferential.”Just as cars sitting in traffic on the highway are unable to turn around and drive in the opposite direction, Aspuru-Guzik said, excitons in this system are able to flow in only one direction, around the edges of the film.What’s more, Yuen-Zhou said, the quantum mechanics of the system permit a good deal of flexibility, allowing excitons to flow around defects in the material, just as a stream flows around obstructions.While it may be years before the material finds its way into commercial solar panels, Aspuru-Guzik believes it has the potential to increase their efficiency by creating a flow of excitons that moves along the panel’s interface, more efficiently transferring energy into electricity.“What we’ve done with this paper is a proof of concept, and we hope it’s the opening to a new era of excitonics.”
As Ebola hysteria dies down in the United States, the international community should not lose sight of a larger issue highlighted by the epidemic — the need to improve health care systems in the poorest African countries, writes Harvard School of Public Health (HSPH) Professor Richard Marlink in new commentary. He advises world leaders to take their cues from the U.S. government’s President’s Emergency Plan for AIDS Relief (PEPFAR) program.HSPH received a total of $362 million from the program for work in Botswana, Nigeria, and Tanzania that included training health care workers, developing monitoring and evaluation systems, strengthening health care infrastructures, and collaborating with local hospitals and clinics that provide treatment for AIDS patients. HSPH’s PEPFAR grants wound down in 2012, and researchers at the School worked with partner organizations to transition activities to full local ownership.Marlink, who is Bruce A. Beal, Robert L. Beal, and Alexander S. Beal Professor of the Practice of Public Health, helped launch and run HSPH’s PEPFAR efforts in Botswana. In his commentary, published November 14, 2014 on GlobalPost, Marlink describes lessons learned from PEPFAR’s success: Focus on outcomes, establish local partnerships, and leave countries better equipped to deal with other health issues. Read Full Story
Earlier this month, President Duterte urged the Senate and the House to pass the national budget by December to avoid what happen to this year’s budget, which was four months delayed. Lawmakers are pushing back their target date for the approval of the final version of the P4.1-trillion national budget for 2020 by at least one day after senators asked for more time to review the fiscal plan. “If there were no hitches, the Senate can ratify the bicameral version of the 2020 national budget on Wednesday or even on Tuesday,” Sotto added. MANILA – The Senate and the House of Representatives is about to beat President Rodrigo Duterte’s deadline of submitting the ratified version of the 2020 national budget by December. Senate President Vicente “Tito” Sotto III also said they eye approving the final version of the budget on Wednesday at the latest “if [there are] no hitches.” Senate Finance committee chairman Juan Edgardo “Sonny” Angara said Monday that about 90 percent of the conflicting provisions of the two chambers of the Congress in next year’s budget were reconciled. “We are approximately 90 to 95% reconciled with the House,” Angara said. “Sen. [Panfilo] Lacson’s proposals like placing some limits on administrative costs and having the possibility of greater local projects have also been adopted in some form in the budget provisions.” Duterte was only able to sign the 2019 budget into law in April after the Senate and House took time to transmit the signed enrolled copy of the bill over disagreements on lawmakers’ insertions./PN According to Angara, the Senate and House contingents for the bicameral conference committee on next year’s national budget are about to meet again on Tuesday to iron out the remaining disagreeing provisions.
The senior national team the Black Stars last Sunday commenced training for their international friendly against the Oranje national team of the Netherlands.Captain Asamoah lead dressing timeKPB get set to touch the leather Stretching time Credit: Ghana FA