Reversibly Switching Wormlike Micelles Formed by a Selenium-Containing Surfactant and Benzyl Tertiary Amine Using CO₂/N₂ and Redox Reaction

Multiresponsive wormlike micelles (WLMs) remain a significant challenge in the construction of smart soft materials based on surfactants. Herein, we report the preparation of a viscoelastic wormlike micellar solution based on a new redox-responsive surfactant, sodium dodecylselanylpropyl sulfate (SDSePS), and commercially available benzyl tertiary amine (BTA) in the presence of CO₂. In this system, SDSePS can be reversibly switched on (selenide) and off (selenoxide) by a redox reaction, akin to that previously reported for benzylselanyl or phenylselanyl surfactants. By alternately adding H₂O₂ and N₂H₄·H₂O, WLMs can be reversibly broken and formed because of the transformation of the hydrophilic headgroup of SDSePS, originating from the reversible formation of selenoxide. Moreover, WLMs can also be switched on and off by cyclically bubbling CO₂ and N₂ because of the variation of the binding interaction between SDSePS and BTA, resulting from the reversible protonation of BTA. This interesting and unique multiresponsive behavior makes the current WLMs a potential candidate for smart control of the “sol–gel” transition or substantial thickening of solutions

Is Sexual Ornamentation an Honest Signal of Male Quality in the Chinese Grouse (<i>Tetrastes sewerzowi</i>)?

<div><p>We examined the variation in sexual ornamentation of male Chinese grouse (<i>Tetrastes sewerzowi</i>) in the Gansu Province, China, seeking to identify factors involved in whether ornament size and brightness are honest signals of male quality. Compared to unmated males, mated males had significantly larger and redder combs and, although they did not have significantly larger territories, they defended them more vigorously. Mated males had significantly higher blood carotenoid and testosterone levels, significantly better body condition, and significantly lower parasite loads than unmated males. Our findings are thus consistent with the hypothesis that comb size and color are honest signals of better male quality in the grouse, mediated through lower parasite loads and/or higher testosterone levels.</p></div

The correlations between comb redness, condition score and parasite burdens of male Chinese grouse.

<p>Mated males (closed circles), Unmated males (open circles).</p

The correlation between plasma carotenoid concentration of male Chinese grouse and (a) comb size and (b) comb redness.

<p>Mated males (closed circles), Unmated males (open circles).</p

Correlation between testosterone level and sexual traits and the comparison of sexual traits between mated and unmated males and female Chinese grouse in the Lianhuashan Nature Reserve, central China.

<p>Note: General Linear Model (GLM) for the analysis, sampling year, sampling date and age were as fixed effects.</p

Comparing the supra-orbital comb between mated and unmated male Chinese grouse (a, unmated male grouse; b, mated male grouse).

<p>Comparing the supra-orbital comb between mated and unmated male Chinese grouse (a, unmated male grouse; b, mated male grouse).</p

The correlation between comb size and color within the female, mated male and unmated male Chinese grouse.

<p>The correlation between comb size and color within the female, mated male and unmated male Chinese grouse.</p

Behavioral comparisons of mated and unmated male Chinese grouse (a) territorial flights, (b) flutter-jumps.

<p>The numbers above the bars are sample sizes.</p

CO₂‑Switchable Pickering Emulsion Using Functionalized Silica Nanoparticles Decorated by Amine Oxide-Based Surfactants

Herein, we describe a novel CO₂-switchable oil-in-water Pickering emulsion stabilized by functionalized silica nanoparticles with a trace amount of myristylamidopropyl amine oxide (C₁₄PAO), which is commercially available, and readily biodegradable. C₁₄PAO in the current system has been demonstrated to be CO₂-responsive. Upon alternately bubbling CO₂ and N₂ under mild conditions (30 °C, 40 mL min^–1), C₁₄PAO is reversibly switched between cationic and nonionic forms, and is thereby adsorbed on or desorbed from the surface of the particles. In this way, interfacially active particles are formed and adsorbed on the surface of oil droplets, stabilizing the emulsion (CO₂), or disrupted and desorbed from the surface of oil droplets, breaking the emulsion (N₂). As compared to the traditional acid/base cycle, switching the current system with CO₂/N₂ multiple times does not lead to any evident changes in either macroscopic appearance or microscopic size. Moreover, this CO₂-responsive Pickering emulsifier can be recycled when fresh oil was added after removing the original oil, and theoretically the cycling can be maintained, conforming to the principle of green and energy-saving processing. It offers a green, efficient, and recyclable container for oil product transportation, especially in high temperature area. Such a strategy is also suitable for other amine oxide-based surfactants, and does not require complicated organic synthesis

CO₂ and Redox Dual Responsive Pickering Emulsion

Herein, we described for the first time a CO₂ and redox dual responsive paraffin oil-in-water Pickering emulsion stabilized by the modified silica nanoparticles with Se-containing tertiary amine, SeTA, in which the tertiary amine serves as a CO₂-sensitive group, and the Se atom serves as a redox-sensitive center. The Pickering emulsion can be reversibly switched between stable and unstable states by bubbling CO₂ and N₂ in the reduced state, or with the addition of H₂O₂ and Na₂SO₃ in the absence of CO₂, because of the adsorption and desorption of SeTA on the silica surface. The former is mainly attributed to a CO₂-controllable electrostatic attraction, resulting from the transition of molecules between cationic and nonionic states; whereas, the latter is ascribed to a redox-tunable hydrogen bonding, originating from the transition of molecules between selenide and selenoxide. However, in the presence of CO₂, redox can only induce a change in the droplet size, not demulsification. These interesting and unique multiresponsive behaviors endow the Pickering emulsion with a capacity for intelligent control of emulsification and demulsification, as well as the droplet size, which may be an asset for a myriad of technological applications in biomedicine, microfluidics, drug delivery, and cosmetics