Energy crisis and environmental issues have encouraged the adoption of electric vehicle as an alternative transportation option to the conventional internal combustion engine vehicle. Recently, the ...development of smart grid concept in power grid has advanced the role of electric vehicles in the form of vehicle to grid technology. Vehicle to grid technology allows bidirectional energy exchange between electric vehicles and the power grid, which offers numerous services to the power grid, such as power grid regulation, spinning reserve, peak load shaving, load leveling and reactive power compensation. As the implementation of vehicle to grid technology is a complicated unit commitment problem with different conflicting objectives and constraints, optimization techniques are usually utilized. This paper reviews the framework, benefits and challenges of vehicle to grid technology. This paper also summarizes the main optimization techniques to achieve different vehicle to grid objectives while satisfying multiple constraints.
There is often a trade-off between mechanical properties (modulus and toughness) and dynamic self-healing. Here we report the design and synthesis of a polymer containing thermodynamically stable ...whilst kinetically labile coordination complex to address this conundrum. The Zn-Hbimcp (Hbimcp = 2,6-bis((imino)methyl)-4-chlorophenol) coordination bond used in this work has a relatively large association constant (2.2 × 10
) but also undergoes fast and reversible intra- and inter-molecular ligand exchange processes. The as-prepared Zn(Hbimcp)
-PDMS polymer is highly stretchable (up to 2400% strain) with a high toughness of 29.3 MJ m
, and can autonomously self-heal at room temperature. Control experiments showed that the optimal combination of its bond strength and bond dynamics is responsible for the material's mechanical toughness and self-healing property. This molecular design concept points out a promising direction for the preparation of self-healing polymers with excellent mechanical properties. We further show this type of polymer can be potentially used as energy absorbing material.
Recently, incorporating guanidium (GA) cations into organolead halide perovskites is shown to effectively improve the stability and performance of the solar cells. However, the underlying mechanisms ...that govern the GA incorporation have remained unclear. Here, FAPbI3 is used as a basic framework to investigate experimentally and theoretically the role of cesium (Cs) and bromine (Br) substitutions in GA+ incorporation. It is found that simultaneous introduction of the small‐size Cs+ and Br– in the FAPbI3 lattice is critical to create sufficient space for the large GA+ and that the presence of the Cs+ prevents the formation of a GA‐contained low‐dimensional phase, which both assist GA+ incorporation. Upon entering the perovskite lattice, the GA+ can stabilize the lattice structure via forming strong hydrogen bonds with their neighboring halide ions. Such structure modification suppresses halide vacancy formation, thus leading to improved material properties. Compared to the GA‐free perovskite reference samples, the optimal system GA0.05Cs0.15FA0.8Pb(I0.85Br0.15)3 exhibits substantially improved thermal and photothermal stability, as well as increased photocarrier lifetime. Solar cells fabricated with the optimal material system show an excellent photovoltaic performance, with the champion device reaching a power conversion efficiency of 21.3% and an open circuit voltage of 1.229 V.
Through experimental and theoretical investigation, the synergetic effects of Cs and Br in assisting incorporation of guanidium (GA) in FAPbI3 are revealed. It is found that GA incorporation enhances the bonding with surrounding halides and elevates the formation energy of halide vacancies, resulting in improved stability and photovoltaic performance.
A stiff and healable polymer is obtained by using the dynamic‐covalent boroxine bond to crosslink PDMS chain into 3D networks. The as‐prepared polymer is very strong and stiff, and can bear a load of ...more than 450 times its weight. When damaged, it can be completely healed upon heating after wetting.
Self-healing hydrogels can heal themselves on the damaged sites, which opens up a fascinating way for enhancing lifetimes of materials. Polypeptide/poly(amino acid) is a class of polymers in which ...natural amino acid monomers or derivatives are linked by amide bonds with a stable and similar secondary structure as natural proteins (α-helix or β-fold). They have the advantages of nontoxicity, biodegradability, and low immunogenicity as well as easy modification. All these properties make polypeptides extremely suitable for the preparation of self-healing hydrogels for biomedical applications. In this review, we mainly focus on the progress in the fabrication strategies of polypeptide-based self-healing hydrogels and their biomedical applications in the recent 5 years. Various crosslinking methods for the preparation of polypeptide-based self-healing hydrogels are first introduced, including host-guest interactions, hydrogen bonding, electrostatic interactions, supramolecular self-assembly of β-sheets, and reversible covalent bonds of imine and hydrazone as well as molecular multi-interactions. Some representative biomedical applications of these self-healing hydrogels such as delivery system, tissue engineering, 3D-bioprinting, antibacterial and wound healing as well as bioadhesion and hemostasis are also summarized. Current challenges and perspectives in future for these “smart” hydrogels are proposed at the end .
Polypeptides with the advantages of nontoxicity, biodegradability, hydrophilicity and low immunogenicity, are extremely suitable for the preparation of self-healing hydrogels in biomedical applications. Recently, the researches of polypeptide-based self-healing hydrogel have drawn the great attentions for scientists and engineers. A review to summarize the recent progress in design and biomedical applications of these polypeptide-based self-healing hydrogels is highly needed. In this review, we mainly focus on the progress in fabrication strategies of polypeptide-based self-healing hydrogels and biomedical applications in recent five years and aim to draw the increased attention to the importance of these “smart” hydrogels, facilitating the advances in biomedical applications. We believe this work would draw interest from readers of Acta Biomaterialia.
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Wide bandgap (WB) organic–inorganic hybrid perovskites (OIHPs) with a bandgap ranging between 1.7 and 2.0 eV have shown great potential to improve the efficiency of single‐junction silicon or ...thin‐film solar cells by forming a tandem structure with one of these cells or with a narrow bandgap perovskite cell. However, WB‐OIHPs suffer from a large open‐circuit voltage (Voc) deficit in photovoltaic devices, which is associated with the phase segregation of the materials under light illumination. In this work the photoinstability is demonstrated and Voc loss can be addressed by combining grain crystallization and grain boundary passivation, achieved simultaneously through tuning of perovskite precursor composition. Using FA0.17Cs0.83PbI3–xBrx (x = 0.8, 1.2 1.5, and 1.8), with a varied bandgap from 1.72 to 1.93 eV, as the model system it is illustrated how precursor additive Pb(SCN)2 should be matched with a proper ratio of FAX (I and Br) to realize large grains with defect‐healed grain boundaries. The optimized WB‐OIHPs show good photostability at both room‐temperature and elevated temperature. Moreover, the corresponding solar cells exhibit excellent photovoltaic performances with the champion Voc/stabilized power output efficiency reaching 1.244 V/18.60%, 1.284 V/16.51%, 1.296 V/15.01%, and 1.312 V/14.35% for WB‐OIHPs with x = 0.8, 1.2, 1.5, and 1.8, respectively.
The photoinduced phase segregation in wide bandgap hybrid perovskites are greatly suppressed by combining grain crystallization and grain boundary passivation. As a result, the open‐circuit voltage (Voc) loss of the corresponding devices is highly reduced, demonstrating a monotonic increase of Voc with increasing of bandgap from 1.72 to 1.93 eV.
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•US equipment typically used in a common laboratory can degrade PFAS.•DFUS/PS is efficient for PFAS defluorination, particularly for PFOA (~100%).•DFUS/PS process can efficiently ...degrade PFAS in the contaminated soil.•Degradation pathways and kinetics of PFOA are studied.
Ultrasound (US) can degrade per- and polyfluoroalkyl substances (PFAS) by the cavitation or pyrolysis effect. In this study, we find that the US equipment typically used in a common laboratory, such as 20 kHz and 43 kHz for cleaning or homogenisation, can degrade PFAS, although the process is slow (with approximately 14.6% and 20.1% defluorination after 6 h, respectively). To accelerate the degradation process, a dual-frequency US is combined with persulfate (PS) to synergistically degrade PFAS in water and soil. Typical PFAS including perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and 1H, 1H, 2H, 2H-perfluorooctanesulfonic acid (6:2 FTS) are used to evaluate the degradation performance of dual-frequency US/PS in water. After 6 h of degradation, the defluorination percentage is, from highest to lowest, PFOA (100 ± 1.2%) > 6:2 FTS (86.9 ± 0.9%) > PFOS (46.5 ± 1.0%). Interestingly, the dual-frequency US/PS process can also efficiently degrade PFAS in the contaminated soil, with a 62–71% degradation of 14 PFAS (28 is the maximum number of PFAS that can be quantitatively monitored), representing an encouraging progress. Finally, the degradation pathways and kinetics of PFOA are studied by monitoring the degradation intermediates, and by indicating the combination of the dual-frequency US/PS is not simply addition with each other, but with a synergistic effect of degradation.
Akaganeite ( beta -FeOOH) nanorods with a hollandite-type structure were prepared by a simple solution method, and were characterized by X-ray diffraction, Fourier transform infrared spectroscopy ...(FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy and nitrogen adsorption-desorption isotherms. The ion-exchange properties of the nanorods toward As(V) ions were investigated. The ion-exchange mechanism between the surface hydroxyl groups and As(V) ions was revealed by FTIR and XPS. From the results of the experiments, it is found that the surface hydroxyl groups which hydrogen bonded water molecules located outside of the hollandite channels play key roles in the ion-exchange process. In addition, the as-prepared beta -FeOOH could be readily regenerated using NaOH solution and be repeatedly used.
Abstract
Water fountains (WFs) are thought to be objects in the morphological evolution of the circumstellar envelopes of low- and intermediate-mass evolved stars, transitioning from spherically ...symmetric to asymmetric shapes. We used databases of circumstellar 1612 MHz OH and 22.235 GHz H
2
O maser sources to search for new WF candidates using the criterion of a larger velocity range of the H
2
O maser emission compared to that of the OH maser emission. Thus, it is in principle possible to identify WFs with H
2
O velocity ranges smaller than those for the previously known WFs. For the OH maser line, we analyzed database entries of 8474 observations from 2195 sources, and 6085 observations from 3642 sources for the H
2
O maser line. After a close examination of the velocity ranges and line profiles, we identified 11 sources that meet the criterion mentioned above. We examined the IRAS colors of the selected sources and found that two of them (IRAS 19069+0916 and IRAS 19319+2214) are in the color region for post-AGB stars. We find that the maser velocity criterion can discover other astrophysically interesting objects than just WFs. Such objects may include peculiar planetary nebulae with maser emissions and stellar merger remnants.
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