Meine Merkliste  

More friction for polyelectrolyte brushes

Skeletal joints must provide lubrication under considerable load. Lubrication between two sliding surfaces in aqueous environments can be greatly enhanced by polyelectrolyte brushes ( 1 ): Long macromolecular chains that bear charges at each repeating unit are grafted densely to a planar or curved surface. In the so-called osmotic limit (low salt concentrations), a large fraction of the counterions are confined within the brush layer, thus creating an enormous osmotic pressure (see the figure, left). Surface forces apparatus (SFA) ( 2 ) studies revealed a marked repulsion between such surfaces ( 3 ), and Klein and co-workers ( 4 ) showed that this effect very efficiently lubricates polyelectrolyte brush interfaces. It is now generally believed that lubrication in many biological systems works according to the same principle. On page 1434 of this issue, Yu et al. ( 5 ) add a twist to this story by studying the same problem in a SFA and finding that traces of di- and trivalent ions can increase the frictional force between two polyelectrolyte brush layers, dramatically so for Y3+ ions.

Autoren:   Matthias Ballauff
Journal:   Science
Band:   360
Ausgabe:   6396
Jahrgang:   2018
Seiten:   1399
DOI:   10.1126/science.aat5343
Erscheinungsdatum:   29.06.2018
Mehr über Science International / AAAS
  • Fachpublikationen

    Random number generators go public

    On 10 July, researchers in Chile will unveil an online public random number service. Later in July, the U.S. National Institute of Standards and Technology (NIST) will launch its Randomness Beacon as a permanent service, upgrading a pilot program that began in 2013. Brazil, too, is planning ... mehr

    When the cure kills—CBD limits biodiversity research

    The Convention on Biological Diversity (CBD) commits its 196 nation parties to conserve biological diversity, use its components sustainably, and share fairly and equitably the benefits from the utilization of genetic resources. The last of these objectives was further codified in the Conve ... mehr

    See-through solar cells could power offices

    Solar windows turn some of the light shining through into electricity. They've been on the market for years. But many of these windows absorb some visible light, leaving them with a reddish or brownish hue, a trait frowned on by architects. Now, new versions are on the way that absorb invis ... mehr

  • News

    Die spannendsten Wissenschaftsnachrichten des Jahres 2017

    (dpa) Das Top-Wissenschaftsereignis 2017 fand schon vor 130 Millionen Jahren statt: Die im Sommer von Tausenden Astrophysikern beobachtete Verschmelzung zweier Neutronensterne am Rande einer fernen Galaxie kürte das US-Journal «Science» zum Durchbruch des Jahres. Aber auch biomedizinische F ... mehr

    Was wird 2017 spannend in der Wissenschaft?

    (dpa) Embryonen im Labor, Zika-Impfstoffe und die Suche nach einem neunten Planeten in unserem Sonnensystem haben nach Einschätzung des US-Fachjournals «Science» das Zeug zum Wissenschaftsaufreger 2017. Um was geht es dabei genau? Embryonen in Nährlösung Mit ihrem Experiment, menschliche Em ... mehr

    Die zehn wichtigsten Entdeckungen 2016

    (dpa) Das Fachmagazin Science hat die zehn wichtigsten wissenschaftlichen Durchbrüche des ausklingenden Jahres gekürt. Ein Überblick:  Im Februar gab das US-Observatorium Ligo die Entdeckung von Gravitationswellen von zwei verschmelzenden Schwarzen Löchern bekannt. Bereits vor einem Jahrhu ... mehr

Ihr Bowser ist nicht aktuell. Microsoft Internet Explorer 6.0 unterstützt einige Funktionen auf Chemie.DE nicht.