Spotlights Cite This: J. Phys. Chem. Lett. 2017, 8, 5687-5687
Spotlights: Volume 8, Issue 22
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COMPRESSIBILITY ANOMALIES IN STRETCHED WATER AND THEIR INTERPLAY WITH DENSITY ANOMALIES
IT IS COMPLICATED: CURVATURE, DIFFUSION, AND LIPID SORTING WITHIN THE TWO MEMBRANES OF ESCHERICHIA COLI Bacteria have been around far longer than humans, and they are ubiquitous in our daily lives. Most people know that these microorganisms can cause illness, but they may not know that bacteria are crucial elements of our digestive systemsand for the existence of cheese and pickles. With bacteria found everywhere on Earth, it is no surprise that they are a constant subject of scientific research. Hsu et al. (10.1021/acs.jpclett.7b02432) studied Escherichia coli and reveal unprecedented details of the intricate relationship between both of its membranes and the proteins embedded within them. They found that the movement of bacterial membranes and the flow of individual lipids within them are influenced by various different factors, most significantly the type and number of surrounding integral membrane proteins. Some bacterial membrane proteins induce lipid sorting while others do not. The authors describe chemical details of the dynamical behavior of both the inner and outer membranes as well as several crucial bacterial proteins, which could aid in our understanding of how bacterial membrane proteins and lipids contribute to the protection of the bacterial cell.
Water is an everyday liquid, but its many anomalies remain puzzling. For example, a typical liquid will almost always contract when frozen, but water expands. You can see the evidence all around you: Ice floats in a glass of water, and water wreaks havoc on our roads when it seeps into cracks and freezes into ice. Because water is involved in so many natural phenomena and technological processes, its anomalies are of great interest to scientists, including Holten et al. (10.1021/ acs.jpclett.7b02563). The authors used small drops of water trapped inside a quartz crystal to generate a mechanical tension (negative pressure) on the liquid. By measuring the sound velocity in water under these extreme conditions, they show the existence of a line of compressibility maxima, which plays a key role in the longstanding debate about water anomalies. The authors demonstrate that the relations between different lines of extrema, being based on general thermodynamic relations, are applicable to any liquid with a temperature of maxima of density (TMD) line, and the findings provide a general framework for understanding the anomalies of other liquids presenting a density maximum.
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pubs.acs.org/JPCL
SMALL LEVITATING ORDERED DROPLET CLUSTERS: STABILITY, SYMMETRY, AND VORONOI ENTROPY
The ability to make diagnoses in the field is crucial for global health, and such efforts have been helped by major advances in microtechnology, including biomicro/nanoelectromechanical systems (bioMEMS/NEMS), microfluidics, and lab-on-a-chip devices. Along with these emerging technologies comes the need for new methods to trace and manipulate small objects in order to analyze small volumes of substances. One particularly important area is microdroplet manipulation. Microdroplets can serve as microreactors in devices and systems of rapid in situ liquid analysis and sensing. One promising area of research is ordered droplet clusters. Previous studies have concentrated on clusters with a large number of droplets, but Fedorets et al. (10.1021/acs.jpclett.7b02657) demonstrate that clusters with an arbitrary small number of droplets also form ordered structures of interest. Small clusters are important because it is easier to trace individual droplets in them, which is crucial for potential applications such as microreactors and for chemical analysis of small volumes of liquid. The authors found that, unlike the clusters with a large number of droplets, small clusters cannot always form a hexagonally symmetric structure. Instead, they produce various more or less symmetric configurations depending on the number of droplets. The symmetry, orderliness, and stability of these configurations can be studied with such a measure of self-organization as the Voronoi entropy. © 2017 American Chemical Society
Published: November 16, 2017 5687
DOI: 10.1021/acs.jpclett.7b02967 J. Phys. Chem. Lett. 2017, 8, 5687−5687
