. 24/7 Space News .
ENERGY TECH
Giant charge reversal observed for the first time
by Staff Writers
Washington DC (SPX) Jul 14, 2017


Snapshots for the distribution of ions near a negatively charged planar surface at different dielectric contrasts. Credit Jianzhong Wu, University of California, Riverside

Charged surfaces submerged in an electrolyte solution can sometimes become oppositely charged. This nonintuitive phenomenon, known as charge inversion, happens when excess counter ions adsorb, or adhere, to the surface. It can occur in a number of chemical and biological settings. In certain situations, theory predicts that a highly charged surface not only changes sign, but can become more highly charged than the original surface. This is known as giant charge reversal, but remains controversial and has never been observed experimentally.

Results reported this week in the Journal of Chemical Physics, from AIP Publishing, confirm, for the first time, giant charge reversal for a surface in contact with a trivalent electrolyte solution. In contrast to previous observations, this did not require a highly charged surface.

The investigators, Zhi-Yong Wang of Chongqing University of Technology in China, and Jianzhong Wu of the University of California, Riverside, found that the dielectric response of the solvent enhances correlation of multivalent ions with oppositely charged surface groups. This facilitates formation of interfacial couplings of opposite charges called Bjerrum pairs, and leads to the observed giant charge reversal.

"Previous theoretical studies did not provide a reliable description of ion interfacial behavior in systems of this type," Wang said. For example, there has been no consensus in the literature about what type of interaction dominates the excess adsorption of multivalent counterions at a charged interface.

The present study accounts for the combined effects of discrete surface charges, ion-excluded volume, surface corrugations and spatial variation of the dielectric response. The latter was allowed to vary since the permittivity and charge dynamics of water in nanopores, such as those in ion channels in cell membranes, can be dramatically different from that in bulk water.

For all these reasons, the researchers took a closer look at the dielectric response of confined electrolytes in a realistic model system. This led to their reported observations here. One reason that previous studies missed the observed giant charge reversal phenomenon, Wang said, is because the inherently heterogeneous, nonuniform nature of the surface charge was neglected.

In the current study, they showed that surface charge heterogeneity and the dielectric response of the solvent are not two separate issues, but must be considered together. In particular, a clear understanding of the role played by image charges is essential to attain consistent interpretation of experimental findings.

These observations indicate that the common assumption of a uniform surface charge density is questionable in the presence of multivalent ions. Such an assumption does not provide a faithful representation of interfacial structure and appears to miss important physics that occur in confined spaces, such as those common in biological systems.

The authors plan to extend their study to look into other mixed electrolyte solutions in contact with curved or irregular surfaces. In addition, more work is needed to account for local dielectric inhomogeneities near charged surfaces, which go beyond traditional models.

The article, "Ion association at discretely-charged dielectric interfaces: Giant charge inversion," is authored by Zhi-Yong Wang and Jianzhong Wu.

ENERGY TECH
Study: Mini cellular antennae helps turn muscle into fat
Washington (UPI) Jul 13, 2017
No matter how much you diet and hit the gym, muscle cells turn to fat as the body ages. Toned bods inevitably become flabby. Blame it on the cilia. New research shows the tiny cellular antennae plays a key role in the muscle-to-fat transformation process. While the realization is unlikely to unlock the fountain of youth, it could help scientists develop new types of regenerative therapi ... read more

Related Links
American Institute of Physics
Powering The World in the 21st Century at Energy-Daily.com


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

ENERGY TECH
NASA Awards Mission Systems Operations Contract

Counting calories in space

NASA Offers Space Station as Catalyst for Discovery in Washington

As the world embraces space, the 50 year old Outer Space Treaty needs adaptation

ENERGY TECH
ISRO Develops Ship-Based Antenna System to Track Satellite Launches

Hypersonic Travel Possibility Heats Up Massively After New Material Discovery

Aerojet Rocketdyne tests Advanced Electric Propulsion System

After two delays, SpaceX launches broadband satellite for IntelSat

ENERGY TECH
Space Race: NASA Faces Competition From SpaceX For First Mars Mission

Curiosity Mars Rover Begins Study of Ridge Destination

For Moratorium on Sending Commands to Mars, Blame the Sun

Tributes to wetter times on Mars

ENERGY TECH
China develops sea launches to boost space commerce

Chinese satellite Zhongxing-9A enters preset orbit

Chinese Space Program: From Setback, to Manned Flights, to the Moon

Chinese Rocket Fizzles Out, Puts Other Launches on Hold

ENERGY TECH
ASTROSCALE Raises a Total of $25 Million in Series C Led by Private Companies

Korean Aerospace offices raided in anti-corruption probe

LISA Pathfinder: bake, rattle and roll

Iridium Poised to Make Global Maritime Distress and Safety System History

ENERGY TECH
Signature analysis of single molecules using their noise signals

Long Duration Experiments Reach 1,000th Day

Spacepath Communications Announces Innovative Frequency Converter Systems

Sorting complicated knots

ENERGY TECH
Molecular Outflow Launched Beyond Disk Around Young Star

Hidden Stars May Make Planets Appear Smaller

Astronomers Track the Birth of a 'Super-Earth'

Big, shape-shifting animals from the dawn of time

ENERGY TECH
Juno Completes Flyby over Jupiter's Great Red Spot

Juno spots Jupiter's Great Red Spot

New Horizons Video Soars over Pluto's Majestic Mountains and Icy Plains

New evidence in support of the Planet Nine hypothesis









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.