NEWS OF TH E WEEK
LAYING OUT THE ATTAINABLE CLIMATE CHANGE: Major technology GREENHOUSE GASES Carbon dioxide emissions from fossil fuels and industrial processes dominate anthropogenic emissions.
changes could still restrain global warming, UN report says
H
OLDING HUMAN-CAUSED global warming to
an internationally agreed-on level is still possible, but it will require large-scale technological shifts, says a United Nations report released on April 13. That level, set at a climate summit held in Copenhagen four years ago, is an average global temperature increase of 2 °C above preindustrial Nitrous oxide Fluorinated gases levels by 2100. 6% 2% “Only major institutional and CO2 from CO2 from deforestation, technological change will give fossil fuels, other landa better than even chance that industrial use changes processes 11% global warming will not exceed 65% this threshold,” according to Methane 16% the report from the Intergovernmental Panel on Climate Change (IPCC). That’s because without additional action to reduce greenhouse gas emisAnthropogenic emissions in 2010 = 49 gigatons of CO2 equivalent sions, emissions are expected (Up 22 gigatons from the CO2 equivalent in 1970) to continue rising, driven by SOURCE: Intergovernmental Panel on Climate Change growth in global population and
TEFLON-PATTERNED PAPER PEPTIDE SYNTHESIS: Nonstick barriers
help build arrays for screening
OST CHEMICAL REACTIONS perform best
M
when shaken or stirred. Active mixing maximizes the chances that reactant molecules will find one another. But chemists who are exploiting small-volume reactions on paper, which is a low-cost platform for synthesis and screening, rarely achieve such thorough mixing. A team in Canada now suggests a solution for that issue: printing Teflon barriers onto paper (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/ anie.201402037). The barriers direct where excess solvent seeps through, promoting mixing. The researchers, led by Ratmir Derda of the University of Alberta, used COU RTESY OF RATMIR DERDA
A liquid-handling robot pipettes reactant solutions onto an array made from Teflonpatterned paper.
VIDEO ONLINE CEN.ACS.ORG
economic activities, according to the report. “The urgency is clear. Global emissions have to peak by the end of this decade,” says Jennifer Morgan, who was a review editor for the report’s chapter on international cooperation and is the climate and energy program director at World Resources Institute, a think tank. Greenhouse gas releases from human activities between 1970 and 2010 represent about half of the cumulative emissions since the Industrial Revolution began about 1750, the report says. CO2 from fossil-fuel burning and industrial processes accounted for about 78% of the total increases in greenhouse gas emissions since 1970, it adds. The report examines geoengineering technologies proposed to remove CO2 from the air or reflect solar radiation. “Whether or not they could actually contribute to the avoidance of future climate change impacts is not clear,” IPCC concludes. Efforts to reduce the amount of solar radiation entering the atmosphere “cannot substitute for emission reductions in the long term,” the report says. These technologies would not address the buildup of greenhouse gases in the atmosphere or effects such as acidification from CO2 uptake by oceans. The report, which focuses on mitigation of climate change, is the last in a series that IPCC has issued in the past seven months. The other two reports examined the science of climate change and adaptation to it. They are expected to influence global negotiations on a new climate treaty.—CHERYL HOGUE
the technique to build 96 small peptides side by side on a sheet of paper about the size of an index card. Printing barriers on paper isn’t a new idea, and researchers have used specially treated liquid-repelling paper before. But combining the barrier and liquidrepulsion concepts provides an improvement over established techniques, says Marya Lieberman, who builds paper analytical devices at the University of Notre Dame. Solvents dissolve the wax barriers often used, and other methods require specialized facilities. Derda’s Teflon technique, in contrast, uses a printer and simple solution processing to form solvent-resistant barriers that make the paper compatible with a wider range of chemistry, she says. Though the peptide yields are not significantly better than those of established solid-phase peptide synthesis techniques, the work is a step forward in streamlining such syntheses, says Helen E. Blackwell, an expert in paper arrays at the University of Wisconsin, Madison. Derda’s paper supports can be stacked as reagents are loaded and excesses are washed away. This “very clever strategy” may eventually facilitate interesting combinatorial chemistry, Blackwell says. Derda has filed a provisional patent on the technology.—CARMEN DRAHL
See the Teflon-patterning process at http://cenm.ag/teflon.
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APRIL 21, 2014
