Display omitted
Supramolecular polymer bottlebrushes (SPBs) consist in the 1D self-assembly of building blocks composed of a self-assembling core with pendant polymer arms. Kinetic hurdles often ...hinder their stimuli-responsiveness in solution. Changing the nature of the solvent should alleviate these hurdles by modulating the self-association strength, leading to stimuli-responsive SPBs.
The SPBs were formed, in various solvents, by hydrogen bond-driven self-assembly of an azobenzene-bisurea decorated with poly(ethylene oxide) polymer arms. The photo-isomerization of the azobenzene unit was studied by UV/visible spectroscopy and proton NMR spectroscopy, whereas the consequences on supramolecular self-assembly were studied by small angle neutron and X-ray scattering.
In water, the assembly was previously shown to be driven by both hydrogen-bonds and strong hydrophobic effects, the latter rendering the system kinetically frozen and the disassembly irreversible. Here we show that in organic solvents such as toluene or chloroform, reversible light-responsive dissociation is achieved. Solvophobic effects in these solvents are expected to be much weaker than in water, which probably allows reversibility of the light-response in the former solvents. The key role of the solvent on the reversibility of the process opens up new perspectives for the design of stimuli-responsive SPBs and their applications in various fields.
•A concept of locally concentrated electrolyte was proposed.•A nanoporous Zn electrode with accurately controlled pore size was fabricated.•Interface-localized concentrated electrolyte was realized ...via space charge effect.•The nanoporous Zn||NaVO3 full cell displayed a high capacity and long lifespan.
Rechargeable aqueous Zn metal batteries are promising for large-scale renewable energy storage. However, the aqueous Zn metal battery chemistry encounters severe irreversibility issues, as manifested by the non-uniform metallic Zn plating and undesired side-reactions of corrosion. Herein, we report a highly-reversible aqueous Zn metal anode with accurately controlled nanopore structure, by which the space charge distribution could be regulated and interface-localized concentrated electrolyte was enabled. Consequently, the nanoporous Zn (npZn) electrode exhibited high electrochemical reversibility for 750 h under the measurement with a combination of electrochemically Zn stripping/plating cycling (1 mA cm−2 and 1 mAh cm−2 for 25 cycles) and resting (50 h), and looping. Moreover, a npZn||NaVO3 cell exhibited a high capacity of 200 mAh g−1 and a long lifespan with considerable capacity retention (76% for 1500 cycles), and high reversibility (Coulombic efficiency of 99.8%), which was more stable than the counterpart with pristine Zn anode (short-circuit after 600 cycles).
The cellular microenvironment is highly heterogeneous and dynamic. Therefore, cells must be equipped with molecular tools to adapt and respond to constantly fluctuating inputs. One such input is ...mechanical force, which activates signalling and regulates cell behaviour in the process of mechanotransduction. Whereas the mechanisms activating mechanotransduction are well studied, the reversibility of this process, whereby cells disassemble and reverse force-activated signalling pathways upon cessation of mechanical stimulation is far less understood. In this review we will outline some of the key experimental techniques to investigate the reversibility of mechanical signalling, and key discoveries arising from them.
Aqueous Zn batteries are promising energy‐storage devices. However, their lifespan is limited by irreversible Zn anodes owing to water decomposition and Zn dendrite growth. Here, we separate aqueous ...electrolyte from Zn anode by coating a thin MOF layer on anode and filling the pores of MOF with hydrophobic Zn(TFSI)2‐tris(2,2,2‐trifluoroethyl)phosphate (TFEP) organic electrolyte that is immiscible with aqueous Zn(TFSI)2–H2O bulk electrolyte. The MOF encapsulated Zn(TFSI)2‐TFEP forms a ZnF2‐Zn3(PO4)2 solid electrolyte interphase (SEI) preventing Zn dendrite and water decomposition. The Zn(TFSI)2‐TFEP@MOF electrolyte protected Zn anode enables a Zn||Ti cell to achieve a high average Coulombic efficiency of 99.1 % for 350 cycles. The highly reversible Zn anode brings a high energy density of 210 Wh kg−1 (of cathode and anode mass) and a low capacity decay rate of 0.0047 % per cycle over 600 cycles in a Zn||MnO2 full cell with a low capacity ratio of Zn:MnO2 at 2:1.
A highly reversible Zn anode is achieved by using a phase‐separation electrolyte, where aqueous electrolyte is separated from Zn by a MOF‐confined thin layer hydrophobic Zn(TFSI)2‐TFEP organic electrolyte and a ZnF2‐Zn3(PO4)2 solid electrolyte interphase (SEI). The Zn anode achieves a high Coulombic efficiency of 99.9 % at 1 mA cm−2 for 350 cycles and stable Zn||MnO2 batteries.
The application of membrane distillation (MD) to hypersaline wastewater treatment is constrained by mineral scaling. Although tuning membrane surface wettability has been recently used to mitigate ...membrane scaling in MD, the effectiveness of this strategy for different scaling types has not been well understood. Furthermore, two important factors that determine the performance of MD membrane, namely wetting resistance and scaling reversibility, have been rarely discussed in MD scaling studies. In this work, we investigated the effects of membrane surface wettability on pore wetting and scaling reversibility associated with gypsum and silica scaling in MD. We challenged a hydrophobic membrane, a Janus membrane with a hydrophilic top layer, and a superhydrophobic membrane with gypsum- and silica-containing feed solutions. Compared to the hydrophobic and Janus membranes, the superhydrophobic membrane delayed scaling induction and enhanced scaling reversibility in gypsum scaling tests, in which the total water recoveries achieved by the tested membranes were inversely correlated to membrane surface hydrophilicity. Also, the superhydrophobic membrane uniquely resisted pore wetting induced by gypsum scaling, probably by preventing feedwater intrusion into membrane pores. In contrast, altering membrane surface wettability was ineffective to improve either scaling reversibility or total water recovery under silica scaling, which did not induce pore wetting for all the tested membranes. We attributed the differences in scaling behaviors as well as the varied responses to membrane surface wettability between gypsum and silica scaling to their distinct scaling mechanisms. The oriented and intrusive gypsum crystallization resulted in pore deformation and discrete crystals that could be detached by physical cleaning. In contrast, the slow kinetics and lack of orientation of silica polymerization formed a thin and crosslinked scaling layer, which was not intrusive but firmly attached to the membrane surface. The results of our study provide valuable insights on the interplays among membrane surface wettability, scaling type, and membrane performance in MD desalination, and suggest that the development of scaling mitigation strategies in MD should be tailored to the varied mechanisms of different scaling types.
•The effects of membrane wettability on MD gypsum and silica scaling were assessed.•Superhydrophobic membrane is resistant to membrane wetting in gypsum scaling.•Superhydrophobic membrane enhances reversibility of gypsum scaling.•Membrane surface wettability does not improve reversibility of silica scaling.•Distinct behaviors of gypsum and silica scaling are due to varied mechanisms.
A novel colorimetric and fluorometric dual-channel sensor DA with a favorable optical property and high specificity via a facile synthesis for Cu2+ was developed. DA showed a remarkably rapid ...response and high selectivity for Cu2+ over other metal ions with low detection limit of 15.1 nM. The sensing mechanism of DA for Cu2+ was based on the chelation-enhanced fluorescence quenching (CHEQ) mechanism, and further confirmed by optical measurements, FTIR, HRMS and DFT calculations. Importantly, DA for sensing Cu2+ possessed excellent sensing performances including colorimetric and fluorometric dual-mode detection, fast response, good reversibility, wide pH response range and strong anti-interference ability. Moreover, the DA could be not only applied to quantitatively detect Cu2+ in environmental water, food and drink samples, but also show highly colorimetric detection of Cu2+ on test strips and silica, indicating its possibility to be utilized as a convenient and low-cost sensor for environment and food monitoring.
Display omitted
•A new colorimetric and fluorometric sensor DA was synthesized.•DA exhibits fast response and ultra sensitivity to Cu2+.•DA is successfully used for tracking Cu2+ in environmental water, food and drink samples.•DA served as an efficient optical solid-state sensor for highly colorimetric detection of Cu2+ on test strips and silica.
Al–Cu–Li alloys are promising lightweight materials for extensive applications in aerospace. As aerospace components often experience strain path changes during service, understanding the resulting ...Bauschinger effect is crucial for optimizing the fatigue resistance and performance of these alloys. This study investigates the role of T1 precipitates in the Bauschinger effect in AA2099. The presence of shearable T1 precipitates has been found to significantly influence the Bauschinger effect by reducing the strengthening effect of T1 precipitates during reverse straining. An analytical expression for slip reversibility has been derived to quantify this phenomenon, and a microstructure-based constitutive model has been developed to accurately predict the Bauschinger effect in AA2099.
•The Bauschinger effect in AA2099 is primarily attributed to shearable T1 precipitates.•An analytical expression is given for slip reversibility.•Microstructure-based model is developed to predict the Bauschinger stress.
3D printing and numerical analysis are combined to design a new class of architected materials that contain bistable beam elements and exhibit controlled trapping of elastic energy. The proposed ...energy‐absorbing structures are reusable. Moreover, the mechanism of energy absorption stems solely from the structural geometry of the printed beam elements, and is therefore both material‐ and loading‐rate independent.
Display omitted
•Forward/reverse degrees of rate control (DoRC) are defined for reversible reactions.•Forward/reverse DoRC are constrained by detailed balance at equilibrium.•Forward/reverse DoRC ...give a thermodynamically consistent rate-control formalism.•Reversible reactions behave like pseudo-elementary steps at equilibrium.
The net rate of a composite reaction is the difference between the forward and reverse reaction rates, which are kinetically distinct despite sharing elementary reaction steps and therefore have different rate-controlling transition states and species. Thus, degrees of rate control defined to identify rate-controlling transition states and species for the net rate confound contributions from the forward and reverse reactions. Herein, the forward and reverse degrees of rate control are defined to independently quantify the extent that species and transition states control the forward and reverse rates in reversible reactions. These degrees of rate control are defined as the relative change in the forward and reverse reaction rates per kBT decrease in the standard-state molecular free energies of transition states and species, and they are related to experimentally measurable quantities such as steady-state fractional coverages, reaction orders, and energies and entropies of activation of the forward and reverse reaction rates. The forward/reverse degrees of rate control represent stoichiometric coefficients for species and transition states in an equilibrium between the initial states and transition states of the apparent rate-controlling steps of forward and reverse overall reactions. At equilibrium, the apparent transition states for the forward reaction and reverse reaction converge, and thus the forward and reverse rate-controlling steps combine to form a single apparent rate-controlling step. This apparent rate-controlling step is comprised of an apparent initial state, transition state, and final state, where the apparent final state of the forward reaction is the apparent initial state of the reverse reaction. The apparent rate-controlling step behaves identically to an elementary step reaction at equilibrium with a pseudo-mass-action rate function given by the transition-state-theory (TST) form rate function (Foley and Bhan, 2020) with a stoichiometric number equal to the affinity-averaged stoichiometric number, σ¯. The ratio of the forward and reverse TST-form rate functions is identical to the overall thermodynamic equilibrium relation, consistent with the principles of microscopic reversibility and detailed balance at equilibrium.
Achieving accurate dosing of scale inhibitors in full reverse osmosis (RO) membrane systems for industrial applications is a critical challenge due to a lack of understanding of membrane fouling ...characteristics. To address this, this study investigated membrane performance at different inhibitor concentrations and proposed a method using ultrasonic phased arrays (UPA) to evaluate the fouling layer's spatial and density characteristics. The study also examined the relationship between fouling reversibility and compaction, and the results showed a clear conversion process from inhibition to exacerbation of membrane fouling by scale inhibitors. Additionally, the fouling layer distribution characteristics were opposite at different concentrations. At insufficient concentrations, the scaling layer forms near the outlet and spreads to the far-end with a continuously decreasing thickness. Conversely, at surplus concentrations, the opposite effect was observed. At sufficient concentrations, the fouling layer thickness and range exhibited a discontinuous distribution. The high-density layer was dominant on the membrane surface and showed low fouling reversibility. However, scale inhibitors were found to minimize fouling density by interfering with ion deposition, reducing the ion content and significantly increasing its reversibility. These findings have significant implications for scale inhibitor efficiency evaluation and scientific application, which can improve industrial membrane system performance.
Display omitted
•The relationship between scale inhibitor concentration and membrane fouling layer characteristics was investigated.•Ultrasonic phased array was introduced to monitor fouling layer spatial and density characteristics.•The membrane fouling layer spatial distribution was significantly affected by the scale inhibitor dosage.•Over dose scale inhibitor increases fouling layer thickness and reduces its reversibility.
PDF