short-range CO-CO repulsion. The team tuned the distance between the two molecules while measuring inelastic electron tunneling, which is the basis of a highly sensitive vibrational spectroscopy method, and analyzed the results with quantum calculations. The analysis revealed various molecular subtleties, including an antisymmetric vibrational mode corresponding to a type of hindered translational motion. The team explains that these vibrational features, which can be used to deduce chemical information, result from the complex interplay between tip-sample distance and the tilting and orbital alignment of the pair of CO molecules.—MITCH JACOBY
ELECTRONIC MATERIALS
▸ Health trackers on the cheap
CREDIT: INTEGRATED NANOTECHNOLOGY LABORATORY/KAUST
Muhammad M. Hussain and his team at King Abdullah University of Science &
A 3-D-printed wearable device features a pulse tracker (left), temperature monitor (center), and moisture sensor (right), all made from inexpensive materials. Technology are on a path paved with sticky notes and silicon to make wearable health trackers more affordable for everyone. Using sticky notes, silver ink, aluminum foil, and clean-room wipes, Hussain’s team created low-cost pressure, moisture, and temperature sensors connected to flexible silicon circuits for data handling and transmission. The team’s work has been accepted and will be published soon in Adv. Mater. Technol. By printing silver ink coils and capacitors on cellulose sticky note substrates, the team created simple temperature and moisture sensors, respectively. Changing temperatures are
BIOBASED MATERIALS
Epoxy resins without BPA A biobased bisphenol can be used to prepare renewable epoxy-amine resins, eliminating the need to use potenially-toxic bisphenol A, chemists report (ChemSusChem 2017, DOI: 10.1002/cssc.20d1601595). BPA is a petroleum-based endocrine disruptor and has been banned by the Food & Drug Administration for use in children’s product packaging. Epoxies, with their hardy chemical and thermal properties, are ubiquitous, used in materials OH HO such as electronics and insuBisphenol A lators. Scientists have been avidly looking for substitutes CH3O for BPA in epoxies. A team led by OCH3 HO Florent Allais of AgroParisTech O has found that syringaresinol, a naturally occurring, non-enOH CH3O docrine-disrupting bisphenol O found in plants such as Syringa OCH3 patula and Magnolia thailandSyringaresinol ica, can be used to produce epoxy-amine resins. The researchers developed a synthesis of syringaresinol via a chemo-enzymatic pathway. Though the epoxy-amine resins based on syringaresinol have mechanical and thermal stabilities that are close to that of BPA-produced resins, the authors say, “the search for a biobased bisphenol able to compete with BPA is not over yet.”—ELIZABETH WILSON
detected as changes in the ink’s electrical resistance, whereas the paper’s dielectric permittivity responds to moisture introduced by sweat, measurably altering the sensor’s electronic profile. To track a person’s pulse, the team built pressure sensors with clean-room wipes sandwiched between strips of aluminum foil. A wipe’s microfibers compress and relax along with the staccato blood flow through the wrist’s radial artery, causing the sandwich sensor’s capacitance to fluctuate with the heartbeat. Each sensor is mounted to a 3-D-printed wristband, resulting in a device that costs about $25 to make, the team reports.—MATT DAVENPORT
MASS SPECTROMETRY
▸ Extending the capabilities of mass spectrometry Mass spectrometry can provide information about the composition of large biomolecular machines, but only if the instrument can handle high mass-to-charge ratios (m/z) with good resolution. That
becomes even harder with complexes that include both proteins and nucleic acids because the nucleic acids don’t acquire enough charge to bring the complexes within the mass range of most instruments. A team led by Albert J. R. Heck of Utrecht University has now modified an Orbitrap mass spectrometer so that it has an ultrahigh mass range, more than twice that of the commercially available Orbitrap extended mass range instrument (Nat. Methods 2017, DOI: 10.1038/nmeth.4147). The researchers achieved this improvement with modifications that increased the transmission and resolution of ions with greater than 20,000 m/z. To demonstrate the instrument’s performance, the researchers analyzed intact bacterial ribosomes and their subunits. The improvements enabled the researchers to resolve relatively small mass differences associated with heterogeneity in the subunits and with the binding of a small ribosomal-associated protein. The researchers also showed that the instrument could analyze a 9-megadalton virus. They propose that such high mass capabilities could make mass spectrometry useful as a quality-control tool for large biological complexes prior to analysis by electron microscopy or crystallography.—CELIA ARNAUD JANUARY 30, 2017 | CEN.ACS.ORG | C&EN
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