1,4‐Diazabicyclo2.2.2octane (dabco) and its derivatives have been extensively utilized as building units of excellent molecular ferroelectrics for decades. However, the homochiral dabco‐based ...ferroelectric remains a blank. Herein, by adding a methyl (Me) group accompanied by the introduction of homochirality to the H2dabco2+ in the non‐ferroelectric H2dabcoTFSA2 (TFSA=bis(trifluoromethylsulfonyl)ammonium), we successfully designed enantiomeric ferroelectrics R and S‐2‐Me‐H2dabcoTFSA2. The two enantiomers show two sequential phase transitions with transition temperature (Tc) as high as 405.8 K and 415.8 K, which is outstanding in both dabco‐based ferroelectrics and homochiral ferroelectrics. To our knowledge, R and S‐2‐Me‐H2dabcoTFSA2 are the first examples of dabco‐based homochiral ferroelectrics. This finding opens an avenue to construct dabco‐based homochiral ferroelectrics and will inspire the exploration of more eminent enantiomeric molecular ferroelectrics.
The first examples of homochiral dabco‐based (dabco=1,4‐diazabicyclo2.2.2octane) ferroelectrics, R‐ and S‐2‐Me‐H2dabcoTFSA2 (TFSA=bis(trifluoromethylsulfonyl)ammonium), were designed from the non‐ferroelectric H2dabcoTFSA2. They show two phase transitions with a transition temperature (Tc) up to 405.8 K and 415.8 K, higher than the Tc of most dabco‐based or homochiral ferroelectrics.
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Electrochemical capacitors: A hierarchical porous graphitic carbon material, composed of macroporous ion‐buffering microreservoirs, ion‐transporting channels, and localized graphitic wall structures, ...is presented (see images; top: 3D skeleton, bottom: carbon platelet). The properties of this new material combine to overcome the electrode kinetic problems normally found in electrochemical capacitors, thus resulting in an excellent high‐rate energy‐storage performance.
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Owing to the weak self-assembly ability of precursor components and the serious crosslinking of neighbouring nanospheres during a hydrothermal process, the synthesis of monodisperse mesoporous ...polymer nanospheres with diameters below 500 nm remains a great challenge. Here we extend the synthesis method of mesoporous silica nanospheres to enable the preparation of ordered mesoporous resorcinol formaldehyde nanospheres with particle size from 80 to 400 nm and mesopores of ~3.5 nm in diameter. By finely tuning the synthesis parameters, multi-layered mesoporous resorcinol formaldehyde hollow nanospheres can be successfully synthesized. Mesoporous carbon nanospheres and hollow nanospheres with high surface area are further obtained through carbonization of the polymer spheres. The resulting mesoporous carbon nanospheres are demonstrated as the host cathode material for lithium-sulphur batteries. The synthesis strategy provides a benchmark for fabricating well-defined porous carbonaceous nanospheres with potential for energy storage and conversion applications.
Molecular piezoelectrics are highly desirable for their easy and environment-friendly processing, light weight, low processing temperature, and mechanical flexibility. However, although 136 years ...have passed since the discovery in 1880 of the piezoelectric effect, molecular piezoelectrics with a piezoelectric coefficient
comparable with piezoceramics such as barium titanate (BTO; ~190 picocoulombs per newton) have not been found. We show that trimethylchloromethyl ammonium trichloromanganese(II), an organic-inorganic perovskite ferroelectric crystal processed from aqueous solution, has a large
of 185 picocoulombs per newton and a high phase-transition temperature of 406 kelvin (K) (16 K above that of BTO). This makes it a competitive candidate for medical, micromechanical, and biomechanical applications.
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Organic ferroelectrics are highly desirable for their light weight, mechanical flexibility and biocompatibility. However, the rational design of organic ferroelectrics has always faced great ...challenges. Anilinium bromide (AB) has two structures reported in the Cambridge Crystallographic Data Centre, which might be an mmmF2/m type ferroelastic (AB‐1). When we studied its ferroelasticity, we were surprised to discover that there was another crystal (AB‐2) in H2O besides this one, and they were very difficult to separate. By changing the solvent, we found that AB‐1 crystals could be formed in ethanol, where ferroelastic domains were visualized by polarized light microscopy, and AB‐2 crystals could be obtained from various crystallization solvents of methanol, isopropanol, N‐butanol, acetonitrile, dimethyl sulfoxide, and N,N‐dimethylformamide, which undergo a ferroelectric phase transition with mm2Fm, showing clear ferroelectricity in two phases. To our knowledge, the regulation of ferroelasticity to ferroelectricity by solvent selective effect is unprecedented in the field of ferroelectrics. This work reveals the important role of solvent effect in organic ferroelectrics.
A solvent selective effect for the regulation of ferroelasticity and ferroelectricity of anilinium bromide is described, which is unprecedented in organic molecular ferroelectrics. Two forms of crystal structure were obtained from different crystallization solvents: ferroelastic AB‐1 and ferroelectric AB‐2. Atom key: Br (green), N (blue), H (light blue), C (gray).
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Although studies on the balance between yield and quality of japonica soft super rice are limited, they are crucial for super rice cultivation. In order to investigate the effects of nitrogen ...application rate on grain yield and rice quality, two japonica soft super rice varieties, Nanjing 9108 （NJ 9108） and Nanjing 5055 （NJ 5055）, were used under seven N levels with the application rates of 0, 150, 187.5,225, 262.5, 300, and 337.5 kg ha^-1. With the increasing nitrogen application level, grain yield of both varieties first increased and then decreased. The highest yield was obtained at 300 kg ha^-1. The milling quality and protein content increased, while the appearance quality, amylose content, gel consistency, cooking/eating quality, and rice flour viscosity decreased. Milling was significantly negatively related with the eating/cooking quality whereas the appearance was significantly positively related with cooking/eating quality. These results suggest that nitrogen level significantly affects the yield and rice quality of japonica soft super rice. We conclude that the suitable nitrogen application rate for japonica soft super rice, NJ 9108 and NJ 5055, is 270 kg ha^-1, under which they obtain high yield as well as superior eating/cooking quality.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A nitrogen‐doped porous carbon monolith was synthesized as a pseudo‐capacitive electrode for use in alkaline supercapacitors. Ammonia‐assisted carbonization was used to dope the surface with nitrogen ...heteroatoms in a way that replaced carbon atoms but kept the oxygen content constant. Ammonia treatment expanded the micropore size‐distributions and increased the specific surface area from 383 m2 g−1 to 679 m2 g−1. The nitrogen‐containing porous carbon material showed a higher capacitance (246 F g−1) in comparison with the nitrogen‐free one (186 F g−1). Ex situ electrochemical spectroscopy was used to investigate the evolution of the nitrogen‐containing functional groups on the surface of the N‐doped carbon electrodes in a three‐electrode cell. In addition, first‐principles calculations were explored regarding the electronic structures of different nitrogen groups to determine their relative redox potentials. We proposed possible redox reaction pathways based on the calculated redox affinity of different groups and surface analysis, which involved the reversible attachment/detachment of hydroxy groups between pyridone and pyridine. The oxidation of nitrogen atoms in pyridine was also suggested as a possible reaction pathway.
N donates more: A nitrogen‐doped carbon monolith was synthesized as a pseudo‐capacitive electrode for use in alkaline supercapacitors. Treatment with ammonia expanded the micropore size distributions and increased the specific surface area of the nitrogen‐doped carbon. Possible redox reaction paths were proposed based on the calculated redox affinity of different groups and surface analysis.
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Abstract
Stellar white-light flares are believed to play an essential role in the physical and chemical properties of the atmosphere of the surrounding exoplanets. Here we report an optical ...monitoring campaign on the nearby flaring system EI Cnc carried out by the Ground-based Wide Angle Camera (GWAC) and its dedicated follow-up telescope. A superflare, coming from the brighter component EI CncA, was detected and observed, in which four components are required to properly model the complex decay light curve. The lower limit of flare energy in the
R
− band is estimated to be 3.3 × 10
32
erg. A total of 27 flares are additionally detected from the GWAC archive data with a total duration of 290 hr. The inferred cumulative flare frequency distribution follows a quite shallow power-law function with a slope of
β
= − 0.50 ± 0.03 over the energy range between 10
30
and 10
33
erg, which reinforces the trend that stars cooler than M4 show enhanced superflare activity. The flares identified in EI Cnc enable us to extend the
τ
–
E
relationship previously established in the white-light superflares of solar-type stars down to an energy as low as ∼10
30
erg (i.e., by 3 orders):
τ
∝
E
0.42±0.02
, which suggests a common flare mechanism for stars with a type from M to solar-like and implies an invariant of
B
1/3
υ
A
in the white-light flares.
Abstract In 2019, the Neutron star Interior Composition ExploreR (NICER) mission released its findings on the mass and radius of the isolated neutron star (INS) PSR J0030+0451, revealing a mass of ...approximately 1.4 solar masses ( M ⊙ ) and a radius near 13 km. However, the recent reanalysis by the NICER collaboration suggests that the available data primarily yield a precise inference of the compactness for this source while the resulting mass and radius are strongly model-dependent and diverse (the 68.3% credible regions just overlap slightly for the ST+PDT and PDT-U models). By integrating this compactness data with the equation of state (EOS) refined by our latest investigations, we have deduced the mass and radius for PSR J0030+0451, delivering estimates of M = 1.48 − 0.10 + 0.09 M ⊙ and R = 12.38 − 0.70 + 0.51 km for the compactness found in the ST+PDT model, alongside M = 1.47 − 0.20 + 0.14 M ⊙ and R = 12.37 − 0.69 + 0.50 km for the compactness in the PDT-U model. These two groups of results are well consistent with each other and the direct X-ray data inference within the ST+PDT model seems to be favored. Additionally, we have calculated the tidal deformability, moment of inertia, and gravitational binding energy for this neutron star. Furthermore, employing these refined EOS models, we have updated mass–radius estimates for three INSs with established gravitational redshifts.
Synthetic nano/micromotors are a burgeoning class of materials with vast promise for applications ranging from environmental remediation to nanomedicine. The motility of these motors is generally ...controlled by the concentration of accessible fuel, and therefore, engineering speed‐regulation mechanisms, particularly using biological triggers, remains a continuing challenge. Here, control over the movement of superassembled porous framework micromotors via a reversible, biological‐relevant pH‐responsive regulatory mechanism is demonstrated. Succinylated β‐lactoglobulin and catalase are superassembled in porous framework particles, where the β‐lactoglobulin is permeable at neutral pH. This permeability allows the fuel (H2O2) to access catalase, leading to autonomous movement of the micromotors. However, at mild acidic pH, succinylated β‐lactoglobulin undergoes a reversible gelation process, preventing the access of fuel into the micromotors where the catalase resides. To one's knowledge, this study represents the first example of chemically driven motors with rapid, reversible pH‐responsive motility. Furthermore, the porous framework significantly enhances the biocatalytic activity of catalase, allowing ultralow H2O2 concentrations to be exploited at physiological conditions. It is envisioned that the simultaneous exploitation of pH and chemical potential of such nanosystems could have potential applications as stimulus‐responsive drug delivery vehicles that benefit from the complex biological environment.
Biocatalytic superassembled metal–organic framework micromotors with a pH‐controlled “on/off” switch is synthesized. Micromotor motion is precisely tuned by the pH‐induced reversible protein conformational change within the frameworks that act as a gate keeper to control the access of chemical fuels. Such nanosystems could have potential applications as smart drug delivery vehicles where diffusive transport can be accelerated with triggered micromotion.
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