Antiferroelectric materials that display double ferroelectric hysteresis loops are receiving increasing attention for their superior energy storage density compared to their ferroelectric ...counterparts. Despite the good properties obtained in antiferroelectric La‐doped Pb(Zr,Ti)O3‐based ceramics, lead‐free alternatives are highly desired due to the environmental concerns, and AgNbO3 has been highlighted as a ferrielectric/antiferroelectric perovskite for energy storage applications. Enhanced energy storage performance, with recoverable energy density of 4.2 J cm−3 and high thermal stability of the energy storage density (with minimal variation of ≤±5%) over 20–120 °C, can be achieved in Ta‐modified AgNbO3 ceramics. It is revealed that the incorporation of Ta to the Nb site can enhance the antiferroelectricity because of the reduced polarizability of B‐site cations, which is confirmed by the polarization hysteresis, dielectric tunability, and selected‐area electron diffraction measurements. Additionally, Ta addition in AgNbO3 leads to decreased grain size and increased bulk density, increasing the dielectric breakdown strength, up to 240 kV cm−1 versus 175 kV cm−1 for the pure counterpart, together with the enhanced antiferroelectricity, accounting for the high energy storage density.
AgNbO3 lead‐free antiferroelectric ceramic is reported to be a promising candidate for energy storage applications. A great breakthrough with high recoverable energy density up to 4.2 J cm−3 and good thermal stability with minimal variation (±5%) over a temperature range of 20–120 °C is achieved in Ta‐modified AgNbO3 ceramics. This is possible because of the enhanced dielectric breakdown strength and antiferroelectricity.
Pores in a solid can effectively reduce thermal conduction, but they are not favored in thermoelectric materials due to simultaneous deterioration of electrical conductivity. Conceivably, creating a ...porous structure may endow thermoelectric performance enhancement provided that overwhelming reduction of electrical conductivity can be suppressed. This work demonstrates such an example, in which a porous structure is formed leading to a significant enhancement in the thermoelectric figure of merit (zT). By a unique BiI3 sublimation technique, pore networks can be introduced into tetrahedrite Cu12Sb4S13‐based materials, accompanied by changes in their hierarchical structures. The addition of a small quantity of BiI3 (0.7 vol%) results in a ≈72% reduction in the lattice thermal conductivity, whereas the electrical conductivity is improved due to unexpected enhanced carrier mobility. As a result, an enhanced zT of 1.15 at 723 K in porous tetrahedrite and a high conversion efficiency of 6% at ΔT = 419 K in a fabricated segmented single‐leg based on this porous material are achieved. This work offers an effective way to concurrently modulate the electrical and thermal properties during the synthesis of high‐performance porous thermoelectric materials.
A porous network structure with excellent electrical properties can enhance the thermoelectric performance of solid materials. This work demonstrates that a porous structure can be introduced into tetrahedrite‐based synthetic minerals by a unique BiI3 sublimation technique. The multiscale architectures simultaneously disrupt phonon transport and trigger energy‐dependent scattering of holes, leading to a superior zT value of 1.15 at 723 K.
Purely organic room-temperature phosphorescence has attracted attention for bioimaging but can be quenched in aqueous systems. Here we report a water-soluble ultralong organic room-temperature ...phosphorescent supramolecular polymer by combining cucurbitnuril (CB7, CB8) and hyaluronic acid (HA) as a tumor-targeting ligand conjugated to a 4-(4-bromophenyl)pyridin-1-ium bromide (BrBP) phosphor. The result shows that CB7 mediated pseudorotaxane polymer CB7/HA-BrBP changes from small spherical aggregates to a linear array, whereas complexation with CB8 results in biaxial pseudorotaxane polymer CB8/HA-BrBP which transforms to relatively large aggregates. Owing to the more stable 1:2 inclusion complex between CB8 and BrBP and the multiple hydrogen bonds, this supramolecular polymer has ultralong purely organic RTP lifetime in water up to 4.33 ms with a quantum yield of 7.58%. Benefiting from the targeting property of HA, this supramolecular polymer is successfully applied for cancer cell targeted phosphorescence imaging of mitochondria.
Two recent publications by Sheikh and Horner and Teng et al. reviewed studies on incorporating vitamin C to treat septic patients; however, a meta-analysis was not offered in either report. This ...commentary extends both reviews by integrating a meta-analysis and sharing aggregated results. Pooled analyses demonstrated a marked reduction in mortality and duration of vasopressor administration in the group with the use of vitamin C.
Social learning in particle swarm optimization (PSO) helps collective efficiency, whereas individual reproduction in genetic algorithm (GA) facilitates global effectiveness. This observation recently ...leads to hybridizing PSO with GA for performance enhancement. However, existing work uses a mechanistic parallel superposition and research has shown that construction of superior exemplars in PSO is more effective. Hence, this paper first develops a new framework so as to organically hybridize PSO with another optimization technique for "learning." This leads to a generalized "learning PSO" paradigm, the *L-PSO. The paradigm is composed of two cascading layers, the first for exemplar generation and the second for particle updates as per a normal PSO algorithm. Using genetic evolution to breed promising exemplars for PSO, a specific novel *L-PSO algorithm is proposed in the paper, termed genetic learning PSO (GL-PSO). In particular, genetic operators are used to generate exemplars from which particles learn and, in turn, historical search information of particles provides guidance to the evolution of the exemplars. By performing crossover, mutation, and selection on the historical information of particles, the constructed exemplars are not only well diversified, but also high qualified. Under such guidance, the global search ability and search efficiency of PSO are both enhanced. The proposed GL-PSO is tested on 42 benchmark functions widely adopted in the literature. Experimental results verify the effectiveness, efficiency, robustness, and scalability of the GL-PSO.
The clinical features and immune responses of asymptomatic individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been well described. We studied 37 ...asymptomatic individuals in the Wanzhou District who were diagnosed with RT-PCR-confirmed SARS-CoV-2 infections but without any relevant clinical symptoms in the preceding 14 d and during hospitalization. Asymptomatic individuals were admitted to the government-designated Wanzhou People's Hospital for centralized isolation in accordance with policy
. The median duration of viral shedding in the asymptomatic group was 19 d (interquartile range (IQR), 15-26 d). The asymptomatic group had a significantly longer duration of viral shedding than the symptomatic group (log-rank P = 0.028). The virus-specific IgG levels in the asymptomatic group (median S/CO, 3.4; IQR, 1.6-10.7) were significantly lower (P = 0.005) relative to the symptomatic group (median S/CO, 20.5; IQR, 5.8-38.2) in the acute phase. Of asymptomatic individuals, 93.3% (28/30) and 81.1% (30/37) had reduction in IgG and neutralizing antibody levels, respectively, during the early convalescent phase, as compared to 96.8% (30/31) and 62.2% (23/37) of symptomatic patients. Forty percent of asymptomatic individuals became seronegative and 12.9% of the symptomatic group became negative for IgG in the early convalescent phase. In addition, asymptomatic individuals exhibited lower levels of 18 pro- and anti-inflammatory cytokines. These data suggest that asymptomatic individuals had a weaker immune response to SARS-CoV-2 infection. The reduction in IgG and neutralizing antibody levels in the early convalescent phase might have implications for immunity strategy and serological surveys.
Mg3(Sb,Bi)2 is a potential nearly‐room temperature thermoelectric compound composed of earth‐abundant elements. However, complex defect tuning and exceptional microstructural control are required. ...Prior studies have confirmed the detrimental effect of Mg vacancies (VMg) in Mg3(Sb,Bi)2. This study proposes an approach to mitigating the negative scattering effect of VMg by Bi deficiency, synergistically modulating the electrical and thermal transport properties to enhance the thermoelectric performance. Positron annihilation spectrometry and Cs‐corrected scanning transmission electron microscopy analyses indicated that the VMg tends to coalesce due to the introduced Bi vacancies (VBi). The defects created by Bi deficiency effectively weaken the scattering of electrons from the intrinsic VMg and enhance phonon scattering. A peak zT of 1.82 at 773 K and high conversion efficiency of 11.3% at ∆T = 473 K are achieved in the optimized composition of Mg3(Sb,Bi)2 by tuning the defect combination. This work demonstrates a feasible and effective approach to improving the performance of Mg3(Sb,Bi)2 as an emerging thermoelectric material.
The formation and tuning of complex defects can effectively enhance the thermoelectric performance of Mg3(Sb,Bi)2. This work proposes an approach to mitigate the negative scattering effect of Mg vacancies by Bi deficiency. The heterovalent vacancies provide a strong phonon scattering, leading to a significant reduction of the lattice thermal conductivity and a superior zT.
Serious environmental and human health problems caused by the abuse of antibiotics have attracted worldwide concern. Recently, metal-organic frameworks (MOFs) with high porosity have drawn wide ...attention for their effects in the adsorption and removal of pollutants from complex matrices. Herein, a high-stable metal organic framework (MOF), i.e., ((ZnCl
)
(
)
·DMF)
, where
=1,3,5-tris((pyridin-4-ylthio)methyl)benzene), MOF
was applied to adsorb and remove tetracycline from sewage and dairy products. The results showed that MOF
exhibited a strong performance in the adsorption of tetracycline. The effects of initial pH values, adsorbent dose, contact time and ionic strength of the adsorption performance of MOF
were investigated. The adsorption kinetics best fit the pseudo-second order model, and the adsorption isotherms matched the Langmuir adsorption model well. It was indicated that both chemical adsorption and physical adsorption play an important role in the adsorption process, and the adsorption of tetracycline was homogeneous and occurred on a monolayer on the surface of MOF
. Additionally, the stability of MOF
and the details of the adsorption mechanism were also investigated. Thus, this study provides a new candidate for the application of MOFs-based adsorbents in the removal of antibiotics from sewage and dairy products.
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