Mechanochromic structural-colored materials have promising applications in various domains. In this Letter, we report three types of reversible mechanochromisms in simple material systems by ...harnessing mechano-responsive wrinkling dynamics including (i) brightness mechanochromism (BM), (ii) hue change mechanochromism (HCM), and (iii) viewable angle mechanochromism (VAM). Upon stretching, the BM device exhibits almost a constant hue but reduces light brightness due to the postbuckling mechanics-controlled deformation, while the HCM device can change the hue from blue to red with almost constant intensity because of the linear elastic mechanics-controlled deformation. The VAM device shows a constant hue because of the thin film interference effect. However, the viewable angles decrease with increasing applied strain owing to the light scattering of wrinkles. All of the mechanochromic behaviors exhibit good reversibility and durability. We clearly elucidated the underlying mechanisms for different mechanochromisms and demonstrated their potential applications in smart displays, stretchable strain sensors, and antipeeping/anticounterfeiting devices.
Magnesium borohydride, Mg(BH4)2, is ball-milled with Ti nano-particles. Such catalyzed Mg(BH4)2 releases more hydrogen than pristine Mg(BH4)2 does during isothermal dehydrogenation at 270, 280, and ...290 °C. The catalyzed Mg(BH4)2 also exhibits better dehydrogenation kinetics than the pristine Mg(BH4)2. Based on kinetics model fitting, the activation energy (Ea) of the catalyzed Mg(BH4)2 is calculated to be lower than pristine Mg(BH4)2. During partial dehydrogenation, the catalyzed Mg(BH4)2 releases 4.23 wt % (wt%) H2 for the second dehydrogenation at 270 °C, comparing to 4.05, and 3.75 wt% H2 at 280, and 290 °C. The reversibility of 4.23 wt% capacity is also one of the highest for Mg(BH4)2 dehydrogenation under mild conditions such as 270 °C as reported. 4 cycles of Mg(BH4)2 dehydrogenation are conducted at 270 °C. The capacities degrade during 4 cycles and tend to be stable at about 3.0 wt% for the last two cycles. By analyzing the hydrogen de/absorption products of the catalyzed sample, Mg(BH4)2 is found to be regenerated after rehydrogenation according to Fourier Transform Infrared (FTIR) spectroscopy. Ti nano-particles can react with Mg(BH4)2 during ball-milling and de/rehydrogenation. The products include TiH1.924, TiB, and TiB2, which can improve the dehydrogenation properties of Mg(BH4)2 from a multiple aspect.
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•The kinetics of Ti–Mg(BH4)2 is enhanced during partial dehydrogenation.•The partial reversibility of Ti–Mg(BH4)2 is improved under mild conditions.•The catalytic mechanism of Ti on the kinetics and reversibility is investigated.
The purpose of this article is to review fibrosis staging systems, reversibility of fibrosis, histologic pattern of fibrosis regression, and recently proposed fibrosis staging systems that address ...the more nuanced fibrosis information needed clinically for management purposes. In most chronic liver diseases, the extent of liver fibrosis often drives patient outcomes. The evolving knowledge of the reversibility of fibrosis and the observed patterns of fibrosis seen in the setting of remodeling/regression can create staging difficulties, and problems in applying the existing “conventional” staging systems. The heterogeneity of liver fibrosis in congestive liver disease is an emerging problem in biopsies from patients with congestive heart failure. The fibrosis staging in these biopsies is of significant import as it is used to determine suitability of some congestive heart disease patients for heart transplantation alone, dual heart and liver transplantation, or be denied transplantation. Pathologist should be aware of these newly recognized concepts, the recently proposed staging systems that attempt to incorporate these new fibrosis patterns and be able to apply the knowledge in daily practice.
•The hepatic repair complex comprises histologic features of regression of cirrhosis.•Incorporation of fibrosis regression in staging e.g. Beijing system is needed.•Fibrosis heterogeneity in congestive liver disease impact biopsy reporting.
•A new Schiff-base probe Sal-cn was developed and used for the reversible detection Al3+ (which can reversibly react to Al3+for 3 times) with high selectivity and sensitivity.•There was a significant ...increase in fluorescence at 435 nm and absorbance at 369 nm and 320 nm of the probe Sal-cn with the addition of Al3+.•LOD values for Al3+ were determined to be 0.21 μM which is lower compared to the reported values.•The mechanism was carried out by Job's plot, HR-MS and DFT, and the endogenous of Al3+ in living cells was investigated.
Aluminium plays an important role in many areas, which has been shown to be associated with some serious diseases. According to the coordination of aluminium with N and O, we conducted probe Sal-cn for the detection of Al3+, the structure of Sal-cn was determined by HR-MS, NMR and IR. Sal-cn showed a good selective and sensitive response towards Al3+ via a fluorescence turn-on output. The detection limit was 0.21 μM. The mechanism was carried out by Job's plot, HR-MS and DFT and related to the coordination of aluminium. What's more, the reversibility showed that Sal-cn could be used for 3 times. Besides, Sal-cn was used for imaging of Al3+ in HEK293T cells.
A simple, selective and reliable probe was investigated for the reversible detection of Al3+ (which can reversibly respond to Al3+ for 3 times), allowing us to visualise and analyse Al3+ with a low detection limit (0.21 μM) in living cells. Display omitted
Understanding physiological and pathological processes in the brain requires tracking the reversible changes in chemical signals with long‐term stability. In their Research Article on page 14429, ...Yang Tian and co‐workers developed a new anti‐biofouling microfiber array to monitor in real time the reversible changes and quantify extracellular concentrations of Ca2+ together with neuron activity across many regions in the mammalian brain for 60 days. Based on this powerful new sensor, the significant influence of ROS on Ca2+ overload and neuron death was discovered during pathogenesis and the treatment of stroke.
•Enhanced dispersion produces high degree of SWI reversibility but long SWR period.•Groundwater level increase/decline rates determine the lag time in SWI/SWR cycle.•Highly heterogeneous ...characteristics leads to fast system response during the SWI.•SWR process consists of a TZ widening stage and a following aquifer flushing stage.
It is essential to understand basis processes affecting the reversibility of seawater intrusion (SWI) and the related timescale after groundwater pumping stopped for coastal groundwater management. Groundwater salinity variations presented by previous studies showed a fast SWI process and the following seawater retreat (SWR) process indicated by overall salinity decrease in the coast karst aquifer in the Dalian Peninsula, northeast China. Cross-sectional variable-density flow and transport simulations using equivalent porous medium (EPM) model, dual-domain (DDM) model and the EPM with a single discrete feature representative of conduit flow (EPM-DF) are conducted to understand the SWI reversibility related to the characteristics of the flow system, including aquifer parameters and seaside boundary conditions. Large dispersity combined with a low salinity concentration at the sea boundary are necessary in the EPM and DDM models to produce a fast SWI and low salinity concentration as observed. The enhanced dispersion in the DDM model enhances the mixing in the transition zone (TZ) and produces more obvious seasonal variation but longer SWR process compared to the EPM model. The EPM-DF model produces significant salinity seasonal variation during the SWI process and a fast decrease in the SWR process. The overall fast system response but low peak concentration during the SWI might be attributed to the highly heterogeneous characteristics of the karst aquifer system, which produces a wide front edge of TZ as observed. The dispersion-dominated EPM and DDM models produced higher degree of SWI reversibility compared to the EPM-DF model, as indicated by the weaker lag effects between groundwater levels and salinity concentration. Moreover, the SWI reversibility may arise not only from the heterogeneous characteristics of the karstic aquifer system but also from the rate for rise in the inland groundwater level during the seasonal variation cycle. An overall SWR process can be divided into two stages: the first stage with rapid decrease in salinity concentration but small changes in toe associated with TZ widening and the second stage with rapid toe retreat during aquifer flushing. The flushing of the brine leakage from the solar salt field may extend the SWR process. Considering this relatively longer water quality response time than the time span in general groundwater management plans, a reasonable objective and how maintain the hydraulic head during the SWI controlling have been of a great concern to the coastal groundwater management.
Studying structure–activity correlations of electrocatalysts is essential for improving the conversion of electrical to chemical energy. Recently, increasing evidence obtained by operando ...characterization techniques reveal that the structural evolution of catalysts caused by the interplay with electric fields, electrolytes and reactants/intermediates brings about the formation of real active sites. Hence, it is time to summarize structural evolution related research advances and envisage future developments. In this Minireview, we first introduce the fundamental concepts associated with structural evolution (e.g., catalysts, active sites/centers and stability/lifetime) and their relevance. Then, the multiple triggers of structural evolution and advanced operando characterizations are discussed. Significantly, a brief overview of structural evolution and its reversibility in heterogeneous electrocatalysis is provided, especially for the representative electrocatalytic oxygen evolution reaction (OER) and CO2 reduction reaction (CO2RR) processes. Lastly, key challenges and opportunities in this exciting field are highlighted.
Structural evolution is crucial to the development of active sites for renewable energy‐conversion technologies involving heterogeneous electrocatalysis. In this Minireview, fundamental concepts related to structural evolution are described. A critical overview of multiple triggers, reversibility and operando characterizations is presented, and the application of structural evolution in important electrocatalytic reactions is presented.
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•The service life of the materials increases via spontaneous repairing the cracks.•Efficiency of the self-healing materials depends on the number of H and G groups.•Among guest ...molecules, the adamantane has a high association constant with the β-CD.•The Fc/β-CD complexes are responsive to the clean and simple electrochemical stimuli.•The azobenzene/β-CD complexes are suitable for light-responsive applications.•Cholic acid as a natural guest promotes the biocompatibility of self-healing materials.•The new synthetic strategies reported in this review allow for different applications.
The self-healing property increases the service life of materials by spontaneously repairing the cracks or fractures. The selection of the appropriate self-healing materials having a fast propagation rate and proper repairing mechanism is important in their high efficiency. Several factors such as time and rate of healing, time of storage, and healing efficiency (obtained from measuring the mechanical properties before and after healing) at the point of fracture have significant effects on the self-healing capability. In recent years, many researchers have focused on non-covalent interactions to fabricate self-healing materials. Among different non-covalent interactions, cyclodextrin-based host–guest (HG) interactions with different guest molecules that can fit inside the cyclodextrin (CD) cavity have attracted the attention of many researchers due to biocompatibility, ease of modification, availability, the capability of CD complex formation with different guest molecules, and the reversible nature of HG complexation. The purpose of the present paper is to review the different strategies of fabricating the HG supramolecular self-healable materials between β-CD and various types of guest molecules such as ferrocene (Fc), adamantane (Ad), azobenzene (Azo), cholic acid (CA), N-vinylimidazole, bromonaphthalene, and other guest molecules. Comparing different strategies makes it possible to properly address the challenges of this field in the future. Each guest molecule which is placed inside the cyclodextrin cavity provides unique properties in the supramolecular self-healable materials. For example, adamantane, ferrocene, azobenzene, and cholic acid, respectively, lead to high stability, electrochemical-sensitivity, light-sensitivity, and biocompatibility of supramolecular self-healable materials. Moreover, different applications of β-CD-based self-healable materials in stimuli-responsive systems, coating, 3D-printing, drug delivery, biomedical, and other applications are summarized in this paper.
The thermodynamic instability of the LiCoO
layered structure at >0.5Li extraction has been considered an obstacle for the reversible utilization of its near theoretical capacity at high cutoff ...voltage (>4.6 V vs Li/Li
) in lithium-ion batteries. Many previous studies have focused on resolving this issue by surface modification of LiCoO
, which has proven to be effective in suppressing phase transformation. To determine the extent to which surface protection of LiCoO
is effective despite its thermodynamic instability and presumably incomplete reversibility involving the O1 phase, here we verify the intrinsic reversibility of bulk LiCoO
with extended lithium extraction by ruling out the effect of a surface. Specifically, first, we show that, contrary to conventional belief, electrochemical cycling of LiCoO
at a cutoff voltage of 4.8 V (vs Li/Li
) results in better cycle stability and lower polarizations than those at 4.6 V. We demonstrate, using an exhaustive suite of characterization tools, that the rapid cycle degradation under high-voltage cycling is mostly caused by the formation of a surface resistive layer; however, these damaged surfaces are leached out faster than they are accumulated above a certain potential, which results in superior cyclability compared with that achieved for less oxidative 4.6-V cycling. This beneficial leaching out of the resistive surface layer serves as a "subtractive" surface modification and plays a role in enhancing the cycle stability and is distinguished from conventional "additive" surface modification such as coating. This approach allows us to decouple factors of the bulk and surface degradations that contribute to the capacity fade and leads to the finding that, in the absence of a resistive surface, the capacity retention of a LiCoO
electrode with 4.8-V cutoff cycling can be intrinsically high, indicating that the instability of the crystalline Li
CoO
( x < 0.5) has a limited effect on the cycle stability. Our findings also explain why the strategy of coating foreign materials on the surface of LiCoO
can improve the high-voltage cycling to some extent despite the expected thermodynamic instability of the highly charged phase.
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