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Ferroelectrics as emerging and attractive catalysts have shown tremendous potential for applications including wastewater treatment, hydrogen production, nitrogen fixation, and organic synthesis, etc. In this study, we demonstrate that molecular ferroelectric crystal TMCM-CdCl 3 (TMCM = trimethylchloromethylammonium) with multiaxial ferroelectricity and superior piezoelectricity has an effective catalytic activity on the direct construction of the pharmacologically important substituted quinoline derivatives via one-pot [3 + 2 + 1] annulation of anilines and terminal alkynes by using N,N-dimethylformamide (DMF) as the carbon source. The recrystallized TMCM-CdCl 3 crystals from DMF remain well ferroelectricity and piezoelectricity. Upon ultrasonic condition, periodic changes in polarization contribute to the release of free charges from the surface of the ferroelectric domains in nano size, which then quickly interacts with the substrates in the solution to trigger the pivotal redox process. Our work advances the molecular ferroelectric crystal as a catalytic route to organic synthesis, not only providing valuable direction for molecular ferroelectrics but also further enriching the executable range of ferroelectric catalysis., (© 2024. The Author(s).)

Ferroelectric materials, traditionally comprising inorganic ceramics and polymers, are commonly used in medical implantable devices. However, their nondegradable nature often necessitates secondary surgeries for removal. In contrast, ferroelectric molecular crystals have the advantages of easy solution processing, lightweight, and good biocompatibility, which are promising candidates for transient (short-term) implantable devices. Despite these benefits, the discovered biodegradable ferroelectric materials remain limited due to the absence of efficient design strategies. Here, inspired by the polar structure of polyvinylidene fluoride (PVDF), a ferroelectric molecular crystal 1H,1H,9H,9H-perfluoro-1,9-nonanediol (PFND), which undergoes a cubic-to-monoclinic ferroelectric plastic phase transition at 339 K, is discovered. This transition is facilitated by a 2D hydrogen bond network formed through O-H···O interactions among the oriented PFND molecules, which is crucial for the manifestation of ferroelectric properties. In this sense, by reducing the number of -CF 2 - groups from ≈5 000 in PVDF to seven in PFND, it is demonstrated that this ferroelectric compound only needs simple solution processing while maintaining excellent biosafety, biocompatibility, and biodegradability. This work illuminates the path toward the development of new biodegradable ferroelectric molecular crystals, offering promising avenues for biomedical applications., (© 2024 Wiley‐VCH GmbH.)

Phase transition materials with switchable second-order nonlinear optical (NLO) properties have attracted extensive attention because of their great application potential in photoelectric switches, sensors, and modulators, while metal-free organics with NLO switchability near room temperature remain scarce. Herein, we report a hydrogen-bonded metal-free organic crystal, 2-methylpropan-2-aminium 2,2-dimethylpropanoate ( 1 ), exhibiting a room-temperature phase transition and favorable NLO switchability. Through investigations on its thermal anomalies, dielectric properties, and crystal structures, we uncover that 1 holds a near-room-temperature phase transition at 303 K from noncentrosymmetric point group C 2 v to centrosymmetric one D 2 h , which is attributed to the order-disorder transformations of both tert -butylamine cations and dimethylpropionic acid anions. Accompanied by symmetry change during the phase transition, 1 exhibits reversible and repeatable NLO "on-off" switchability with a desirable switching contrast ratio of ca. 19 between high and low NLO states. This discovery demonstrates a metal-free organic crystal with NLO switching behavior near room temperature, serving as a promising candidate in smart and ecofriendly photoelectric functional materials and devices.

Transient implantable piezoelectric materials are desirable for biosensing, drug delivery, tissue regeneration, and antimicrobial and tumor therapy. For use in the human body, they must show flexibility, biocompatibility, and biodegradability. These requirements are challenging for conventional inorganic piezoelectric oxides and piezoelectric polymers. We discovered high piezoelectricity in a molecular crystal HOCH 2 (CF 2 ) 3 CH 2 OH [2,2,3,3,4,4-hexafluoropentane-1,5-diol (HFPD)] with a large piezoelectric coefficient d 33 of ~138 picocoulombs per newton and piezoelectric voltage constant g 33 of ~2450 × 10 -3  volt-meters per newton under no poling conditions, which also exhibits good biocompatibility toward biological cells and desirable biodegradation and biosafety in physiological environments. HFPD can be composite with polyvinyl alcohol to form flexible piezoelectric films with a d 33 of 34.3 picocoulombs per newton. Our material demonstrates the ability for molecular crystals to have attractive piezoelectric properties and should be of interest for applications in transient implantable electromechanical devices.

Organic-inorganic halide hybrids have been extensively developed and used in optoelectronic devices because of their superior performance such as ease of assembly, flexible structural tunability, and excellent optoelectronic properties. Ferroelastic strain might be used to modulate and control photoelectric properties such as photovoltaic voltage, while organic-inorganic hybrid ferroelastic semiconductors remain relatively unexplored. Herein, we successfully design a new Sn-base, lead-free hybrid ferroelastic semiconductor, [TPMA] 2 [SnCl 6 ] (TPMA = benzyl trimethylammonium). It undergoes a high-temperature -3 mF -1-type ferroelastic phase transition at 408 K, and intriguingly, its ferroelastic domains can be simultaneously switched under the stimulation of external heat and stress. The ferroelastic phase transition might be derived from the order-disorder transition of organic cations during heating and cooling. Moreover, [TPMA] 2 [SnCl 6 ] also demonstrates a high-temperature dielectric switching property around 408 K, which has good stability and reproducibility. With those benefits, [TPMA] 2 [SnCl 6 ] shows great potential in applications such as energy storage devices, optoelectronic devices, shape memory, intelligent switches, and so on.

An ultrasensitive photoelectrochemical (PEC) aptasensor was originally designed by using ZnIn 2 S 4 /ReS 2 as a photoactive material and AgInS 2 as a signal amplifier. The signal amplifier AgInS 2 was incubated on the terminal of H-DNA (immobilized on the ZnIn 2 S 4 /ReS 2 /FTO surface), leading to an enhanced photocurrent response. Then, due to the introduction of DNA2, the formation of a double-stranded structure caused AgInS 2 to keep away from the electrode surface, and the photocurrent was reduced. In the presence of kanamycin, DNA2 was released from the system due to the competition relationship, and a restored photocurrent response was obtained. The combination of ZnIn 2 S 4 /ReS 2 and AgInS 2 accelerated the electron transfer and enhanced the separation efficiency of photogenerated electron-hole pairs, resulting in an improved performance of the PEC aptasensor, which was capable of accurate and sensitive detection of kanamycin in actual samples.

Organic-inorganic hybrid perovskites (OIHPs) have been emerging as a hot research topic due to their potential applications in energy storage, semiconductors, and electronic devices. Herein, we systematically investigated the synthesis and phase transition behaviors of the enantiomeric OIHPs, ( R ) and ( S )- N , N -dimethyl-3-fluoropyrrolidinium cadmium bromide ([DMFP][CdBr 3 ]), and the hybrid trigonal structure [DMFP] 3 (CdBr 3 )(CdBr 4 ). The enantiomers have a mirror-symmetric structure and enhanced solid-state phase transition points of 417 and 443 K, in contrast to the nonfluorinated parent compound, N , N -dimethyl-pyrrolidinium cadmium bromide ([DMP][CdBr 3 ], 385 K). Moreover, racemic H/F substitution on the pyrrolidinium cations leads to the formation of a trigonal compound, showing above-room-temperature structural phase transition and dominant ferroelasticity. This work discovers chiral enantiomeric OIHPs through H/F substitution, demonstrating a useful chemical synthesis strategy for exploring novel phase transition materials.

As particles carry quantified energy, photon radiation enables orbital transitions of energy levels, leading to changes in the spin state of electrons. The resulting switchable structural bistability may bring a new paradigm for manipulating ferroelectric polarization. However, the studies on molecular orbital breaking in the ferroelectric field remain blank. Here, for the first time, a new mechanism of ferroelectrics-dual breaking of molecular orbitals and spatial symmetry, demonstrated in a photochromic organic crystal with light-induced polarization switching, is formally proposed. By alternating the ultraviolet/visible light irradiation, the states of electron spin and the radial distribution p atomic orbitals experience a change, showing a reversible switch from "shoulder-to-shoulder" form to a "head-to-head" form. This reflects a reversible conversion between π and σ bonds, which induces and couples with the variation of spatial symmetry. The intersection of spatial symmetry breaking and molecular orbital breaking in ferroelectrics present in this work will be more conducive to data encryption and anticounterfeiting., (© 2023 Wiley-VCH GmbH.)

This study aims to establish a method for the simultaneous determination of 7 active components in Dracocephalum tanguticum and to evaluate the quality of medicinal materials from different habitats. The method was established with high performance liquid chromatography(HPLC) and the gradient elution was performed with the mobile phase of acetonitrile-methanol-0.2% phosphoric acid solution at a column temperature of 35 ℃, an injection volume of 15 μL, and a flow rate of 0.6 mL·min~(-1). The detection wavelength was set as 215 nm. With rosmarinic acid as the internal reference, the relative correction factors and the content of other 6 components were calculated. The results were compared with those obtained with the external standard method. The results showed that the samples from Huangzhong county, Qinghai province had the best quality, with the highest content of p-hydroxybenzoic acid, cosmosiin, rosmarinic acid, oleanolic acid, and ursolic acid(9.29, 12.14, 6.02, 3.11, 17.67 mg·g~(-1) respectively). The samples from Chaya county, Tibet autonomous region ranked the second, with the highest content of betulin and betulinic acid(15.53, 7.17 mg·g~(-1), respectively). The method is accurate, reliable, and repeatable and suitable for the simultaneous determination of multiple components in D. tanguticum. The content of functional components varied in the samples from different producing areas and can be used as the indicator for the quality evaluation of medicinal materials.

The mechanism on ferroelectric phase transitions is mainly attributed to the displacive and/or order-disorder transition of internal components since the discovery of the ferroelectricity in 1920, rather than the breaking and recombination of chemical bonds. Here, we demonstrate how to utilize the chemical bond rearrangement in a diarylethene-based crystal to realize the light-driven mm2F1-type ferroelectric phase transition. Such a photoinduced phase transition is entirely driven by switchable covalent bonds with breaking and reformation, enabling the reversible light-controllable ferroelectric polarization switching, dielectric and nonlinear optical bistability. Moreover, light as quantized energy can achieve contactless, nondestructive, and remote-control operations. This work proposes a new mechanism of ferroelectric phase transition, and highlights the significance of photochromic molecules in designing new ferroelectrics for photocontrol data storage and sensing.

The naturally high background value region of Cd derived from the weathering of carbonate has received wide attention. Due to the significant difference in soil physicochemical properties, soil Cd content, and bioavailability of different parent materials in the karst area, there are certain limitations in using the total soil Cd content to classify the environmental quality of cultivated land. In this study, surface soil and maize samples of eluvium and alluvial parent material in typical karst areas were collected systematically; the contents of maize Cd, soil Cd, pH, and oxides were analyzed, the Cd geochemical characteristics of different parent soils and the influencing factors of their bioavailability were revealed, and scientific and effective arable land use zoning suggestions based on the prediction model were suggested. The results showed that the physicochemical properties of different parent material soils in the karst area were obviously different. The alluvial parent material soil had low Cd content but high bioavailability, and the maize Cd exceeding rate was high. The maize Cd bioaccumulation factor was significantly negatively correlated with soil CaO, pH, Mn, and TC, and the correlation coefficients were -0.385, -0.620, -0.484, and -0.384, respectively. Compared with the multiple linear regression prediction model, using the random forest model to predict the maize Cd enrichment coefficient had higher accuracy and precision. Furthermore, a new scheme for the safe utilization of cultivated land at the plot scale based on soil Cd and predicted crop Cd content was proposed in this study, making full use of arable land resources to ensure crop safety.

Organic single-component ferroelectrics are highly desirable for their low molecular mass, light weight, low processing temperature, and excellent film-forming properties. Organosilicon materials with a strong film-forming ability, weather resistance, nontoxicity, odorlessness, and physiological inertia are very suitable for device applications related to the human body. However, the discovery of high- T c organic single-component ferroelectrics has been very scarce, and the organosilicon ones even less so. Here, we used a chemical design strategy of H/F substitution to successfully synthesize a single-component organosilicon ferroelectric tetrakis(4-fluorophenylethynyl)silane (TFPES). Systematic characterizations and theory calculations revealed that, compared with the parent nonferroelectric tetrakis(phenylethynyl)silane, fluorination caused slight modifications of the lattice environment and intermolecular interactions, inducing a 4/ mmm F mm 2-type ferroelectric phase transition at a high T c of 475 K in TFPES. To our knowledge, this T c should be the highest among the reported organic single-component ferroelectrics, providing a wide operating temperature range for ferroelectrics. Moreover, fluorination also brought about a significant improvement in the piezoelectric performance. Combined with excellent film properties, the discovery of TFPES provides an efficient path for designing ferroelectrics suitable for biomedical and flexible electronic devices., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Piezoelectric materials that enable electromechanical conversion have great application value in actuators, transducers, sensors, and energy harvesters. Large piezoelectric ( d 33 ) and piezoelectric voltage ( g 33 ) coefficients are highly desired and critical to their practical applications. However, obtaining a material with simultaneously large d 33 and g 33 has long been a huge challenge. Here, we reported a hybrid perovskite ferroelectric [Me 3 NCH 2 Cl]CdBrCl 2 to mitigate and roughly address this issue by heavy halogen substitution. The introduction of a large-size halide element softens the metal-halide bonds and reduces the polarization switching barrier, resulting in excellent piezoelectric response with a large d 33 (∼440 pC/N), which realizes a significant optimization compared with that of previously reported [Me 3 NCH 2 Cl]CdCl 3 (You et al. Science 2017 , 357 , 306-309). More strikingly, [Me 3 NCH 2 Cl]CdBrCl 2 simultaneously shows a giant g 33 of 6215 × 10 -3 V m/N, far exceeding those of polymers and conventional piezoelectric ceramics. Combined with simple solution preparation, easy processing of thin films, and a high Curie temperature of 373 K, these attributes make [Me 3 NCH 2 Cl]CdBrCl 2 promising for high-performance piezoelectric sensors in flexible, wearable, and biomechanical devices.

Organosilicons have been used extensively in aerospace, electronics, food, medicine and other fields, due to their low viscosity, hydrophobicity, corrosion resistance, non-toxic, and physiologically inert features. Despite extensive interest, however, organosilicon ferroelectric crystals have never been found. Here, by using the chemical design strategy, we successfully obtained a molecular ferroelectric D-chiro-inositol-SiMe 3 with polar P4 3 symmetry, whose spontaneous polarization can be electrically switchable on thin film. The introduction of organosilicon groups endows the thin films with excellent softness, ductility and flexibility (extremely low hardness of 72.8 MPa and small elastic modulus of 5.04 GPa) that are desirable for biomedical and human-compatible applications. As the first case of organosilicon ferroelectric crystal to date, this work offers a new structural paradigm for molecular ferroelectrics, and highlights their potential for flexible bio-electronic applications., (© 2022 Wiley-VCH GmbH.)

Chirality exists everywhere from natural amino acids to particle physics. The introduction of point chirality has recently been shown to be an efficient strategy for the construction of molecular ferroelectrics. In contrast to point chirality, however, axial chirality is rarely used to design ferroelectrics so far. Here, based on optically active 1,1'-bi-2-naphthol (BINOL), which has been applied extensively as a versatile chiral reagent in asymmetric catalysis, chiral recognition, and optics, we successfully design a pair of axial-chiral BINOL multiferroics, ( R )-BINOL-DIPASi and ( S )-BINOL-DIPASi. They experience a 2F1-type full ferroelectric/ferroelastic phase transition at a high temperature of 362 and 363 K, respectively. Piezoelectric force microscopy and polarization-voltage hysteresis loops demonstrate their ferroelectric domains and domain switching, and polarized light microscopy visualizes the evolution of stripe-shaped ferroelastic domains. The axial-chiral BINOL building block promotes the generation of the polar structure and ferroelectricity, and the organosilicon component increases the rotational energy barrier and thus the phase transition temperature. This work presents the first axial-chiral high-temperature multiferroic crystals, offering an efficient path for designing molecular multiferroics through the introduction of axial chirality.

Ferroelectricity, existing in either solid crystals or liquid crystals, gained widespread attention from science and industry for over a century. However, ferroelectricity has never been observed in both solid and liquid crystal phases of a material simultaneously. Inorganic ferroelectrics that dominate the market do not have liquid crystal phases because of their completely rigid structure caused by intrinsic chemical bonds. We report a ferroelectric homochiral cholesterol derivative, β-sitosteryl 4-iodocinnamate, where both solid and liquid crystal phases can exhibit the behavior of polarization switching as determined by polarization-voltage hysteresis loops and piezoresponse force microscopy measurements. The unique long molecular chain, sterol structure, and homochirality of β-sitosteryl 4-iodocinnamate molecules enable the formation of polar crystal structures with point group 2 in solid crystal phases, and promote the layered and helical structure in the liquid crystal phase with vertical polarization. Our findings demonstrate a compound that can show the biferroelectricity in both solid and liquid crystal phases, which would inspire further exploration of the interplay between solid and liquid crystal ferroelectric phases., (© 2022. The Author(s).)

Organic-inorganic hybrid perovskites (OIHPs) have gained tremendous interest for their rich functional properties. However, the coexistence of more than one of ferroelectricity, ferromagnetism and ferroelasticity has been rarely found in OIHPs. Herein, we report a two-dimensional Cr 2+ -based OIHP, [3,3-difluorocyclobutylammonium] 2 CrCl 4 ([DFCBA] 2 CrCl 4 ), which shows both ferroelectricity and ferromagnetism. It undergoes a 4/mmmFm type ferroelectric phase transition at a temperature as high as 387 K and shows multiaxial ferroelectricity with a saturate polarization of 2.1 μC cm -2 . It acts as a soft ferromagnet with a Curie temperature of 32.6 K. This work throws light on the exploration of OIHPs with the coexistence of ferroelectricity and ferromagnetism for applications in future multifunctional smart devices., (© 2022 Wiley-VCH GmbH.)

Background: Recurrent implantation failure (RIF) is a challenge during assisted reproductive technology (ART). In the present study, potential diagnostic biomarkers for the immune status of peripheral blood lymphocyte subsets in patients with RIF were analyzed, with the aim of identifying novel biomarkers that may predict RIF., Methods: A total of 41 participants, including 21 women with RIF and 20 fertile controls, were included in the present study. Functional analysis was performed and the cytokine status of natural killer (NK), T, CD8+ T, T helper (Th), and γδ T cells which are lymphocyte subsets in peripheral blood was measured using flow cytometry. Binary logistic regression analysis adjusted for T follicular helper 1 (Tfh1), Tfh2, Tfh17, and early NK cells was performed to determine the relationship between the peripheral blood lymphocyte subsets and RIF. Potential diagnostic biomarkers were assessed by logistic regression analysis and receiver operating characteristic curves., Results: There were significantly more Tfh1, Tfh17, and NK cells in the RIF group compared with the control group (all P < 0.05). However, the percentage of T, regulatory T (Tregs), and Tfh2 cells, as well as early inhibitory NK cells, was significantly lower in the RIF group compared with the control group (all P < 0.05). Following logistics regression analysis, Treg, Tfh17, and early inhibitory NK cells exhibited significant differences between the two groups. Combination diagnosis using these 3 biomarkers had a higher area under the curve of 0.900 (95% confidence interval: 0.808-0.992, P < 0.001) in the RIF group compared with that in the control group., Conclusion: T, Tregs, Tfh1, Tfh2, Tfh17, NK cells, and early inhibitory NK cells may play important regulatory roles in embryo implantation. The combination of 3 molecular markers (Treg, Tfh17, and early inhibitory NK cells) could provide a high diagnostic value for women with RIF, thus providing novel potential biomarkers for RIF in ART. The present findings could provide a reference either for the clinical treatment of patients with RIF or for future large, well-designed studies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Cai, Tang, Deng, Li, Liang, Meng and Zhou.)

The optical manipulation of polarization has gained widespread attention because it offers a promising route to new contactless memories and switches. However, the current research basically focuses on the photocontrol of data storage rather than data reading, which cannot realize the whole process of contactless write-read-erase data storage. Here, we present a pair of enantiomorphic diarylethene derivative ferroelectric crystals, showing a light-driven phase transition triggered by photoisomerization between the open and closed forms. Under the visible light, they exhibit a binary-domain state in the open form with white color and the band gap of 3.26 eV, while they show a single-domain state in the closed form with blue color and the band gap of 1.68 eV after UV irradiation of 254/365 nm. In addition to writing and erasing ferroelectric domains with light, we can also use light to read their color to determine the polarization state of domains. Moreover, diarylethene derivatives have better thermal stability, higher photoexcited conversion efficiency, and larger changes of the absorption wavelength between two isomers than those in salicylideneaniline derivatives. This work not only discovers the first diarylethene-based ferroelectric crystals but also successfully realizes completely contactless manipulation of write-read-erase data storage in the organic ferroelectric semiconductors.

This study investigates the effects of visual mnemonics and the methods of presenting learning materials on learning visually similar characters for Chinese-as-second-language (CSL) learners. In supporting CSL learners to build robust orthographic representations in Chinese, addressing the challenges of visual similarity of characters (e.g., and ) is an important issue. Based on prior research on perceptual learning, we tested three strategies that differ in the extent to which they promote interrelated attention to the form and meaning of characters: (1) Stroke Sequence, a form-emphasis strategy, (2) Key-images, a form + meaning strategy utilizing visual code, (3) Pithy Formulas with Key-images, a form + meaning strategy combining visual and verbal codes. A pretest-posttest equivalent-group design was adopted. The independent variables were the learning strategy, the method of presenting character pairs (visually similar vs. dissimilar), and testing time. The dependent variables were learners' proportions of accurate responses to reading and writing Chinese characters through a posttest (immediately performed after learning) and a delayed posttest (1 week after learning); a learner experience survey was also administered to investigate learners' opinions on each strategy. Sixty-six non-beginning learners of Chinese participated; they were randomly assigned to one of the two groups in which participants learned ten characters via the three strategies, respectively, differing between whether the characters were presented in similar pairs or dissimilar pairs. Data were analyzed via three-way ANCOVAs. The Pithy Formulas with Key-images and the Key-images generally yielded higher writing accuracy than Stroke Sequence immediately after learning. Notably, the advantage of the Pithy Formulas with Key-images (verbal and visual) over the Key-images (visual) on writing was specific to the participants that learned with visually similar pairs rather than those that learned with dissimilar pairs. All strategies were effective for reading, yet learners' experience ratings favored the two form + meaning strategies over the strategy that focused primarily on form. Suggestions for future research and pedagogical implications on learning visually similar characters were offered., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Chang, Tang, Lee and Chen.)

Shape memory alloys have been used extensively in actuators, couplings, medical guide wires, and smart devices, because of their unique shape memory effect and superelasticity triggered by the reversible martensitic phase transformations. For ferroic materials, however, almost no memory effects have been found for their ferroic domains after reversible phase transformations. Here, we present a pair of single-component organic enantiomorphic ferroelectric/ferroelastic crystals, (R)- and (S)-N-3,5-di-tert-butylsalicylidene-1-(1-naphthyl)ethylamine SA-NPh-(R) and SA-NPh-(S). It is notable that not only can their ferroic domain patterns disappear and reappear during reversible thermodynamic phase transformations, but they can also disappear and reappear during reversible light-driven phase transformations induced by enol-keto photoisomerization, both of which are from P1 to P2 1 polar space groups. Most importantly, the domain patterns are exactly the same in the initial and final states, demonstrating the existence of a memory effect for the ferroic domains in SA-NPh-(R) and SA-NPh-(S). As far as we are aware, the domain memory effect triggered by both thermodynamic and light-driven ferroelectric/ferroelastic phase transformations remains unexplored in ferroic materials. Thermal and optical control of domain memory effect would open up a fresh research field for smart ferroic materials., (© 2022. The Author(s).)

We discovered that [(histamine)(18-crown-6) 2 ][BF 4 ] 2 is a high-temperature host-guest inclusion complex that presents decent piezoelectric properties ( d 33 = 5 pC/N), undergoes a phase transition at 406 K, and also possesses potential ferroelectricity. This work provides a new idea for constructing host-guest inclusion piezoelectrics.

MiR-664b-3p has been reported to play a crucial role in cancer progression. This research explores the biological effect and molecular mechanisms of miR-664b-3p in cell proliferation, apoptosis, migration, and invasion of colon cancer. The expression level of miR-664b-3p and Budding uninhibited by benzimidazole 3 (Bub3) in colon cancer cell lines and tissues were detected and analyzed using quantitative real-time PCR and bioinformatics method. The Western blot measured the expression level of proliferation-related, migration-related, and apoptosis-related proteins. CCK-8 assessed cell viability, and the cell proliferation, migration, and invasion were detected by the Edu assay, wound-healing assay, and transwell assay, respectively. Annexin/propidium iodide (PI) assays detected apoptosis of cells. The target of miR-664b-3p was predicted by bioinformatics methods and then validated by gene engineering technology. MiR-664b-3p was downregulated in colon cancer tissues and cells. The cell proliferation, migration, and invasion of cells were inhibited after transfecting by miR-664b-3p mimics, whereas apoptosis was promoted. Over-expression of miR-664b-3p could reduce the expression of proliferation-promoted proliferating cell nuclear antigen (PCNA), proliferation marker protein Ki-67 (Ki-67), migration-promoted Cyclooxygenase-2 (COX-2), Matrix Metallopeptidase 2 (MMP-2), and Matrix Metallopeptidase 9 (MMP-9), and apoptosis-inhibited protein (Bcl-2) while increasing the expression of apoptosis-promoted BCL2-Associated X Protein (Bax), caspase-3, and caspase-9 proteins. The study indicated that miR-664b-3p plays a significant role in colon cancer and could regulate the progression of colon cancer tumor growth by suppressing the expression of BUB3 protein. These findings provide a novel strategy to screen and treat colon cancer.

A ferroelectric/ferroelastic is a material whose spontaneous polarization/strain can be switched by applying an external electric field/mechanical stress. However, the optical control of spontaneous polarization/strain remains relatively unexplored in crystalline materials, although photoirradiation stands out as a nondestructive, noncontact, and remote-controlled stimulus beyond stress or electric field. Here, we present two new organic single-component homochiral photochromic multiferroics, ( R )- and ( S )- N -3,5-di- tert -butylsalicylidene-1-4-bromophenylethylamine (SA-Ph-Br( R ) and SA-Ph-Br( S )), which show a full ferroelectric/ferroelastic phase transition of 222F2 type at 336 K. Under photoirradiation, their spontaneous polarization/strain can be switched quickly within seconds and reversibly between two ferroelectric/ferroelastic phases with the respective enol and trans -keto forms triggered by structural photoisomerizations. In addition, they possess a superior acoustic impedance characteristic with a value of ∼2.42 × 10 6 kg·s -1 ·m -2 , lower than that of polyvinylidene fluoride (PVDF, (3.69-4.25) × 10 6 kg·s -1 ·m -2 ), which can better match human tissues. This work realizes for the first time that multiple ferroic orders in single-component organic crystals with ultralow acoustic impedance can be simultaneously controlled and coupled by three physical channels (electric, stress, light fields), suggesting their great potential in multichannel data storage, optoelectronics, and related applications compatible with all-organic electronics and human tissues.

The optical control of polarization switching is attracting tremendous interest because photoirradiation stands out as a nondestructive, noncontact, and remote-control means beyond an electric or strain field. The current research mainly uses various photoexcited electronic effects to achieve the photocontrol polarization, such as a light-driven flexoelectric effect and a photovoltaic effect. However, since photochromism was discovered in 1867, the structural phase transition caused by photoisomerization has never been associated with ferroelectricity. Here, we successfully synthesized an organic photochromic ferroelectric with polar space group Pna 2 1 , 3,4,5-trifluoro- N -(3,5-di- tert -butylsalicylidene)aniline, whose color can change between yellow and orange via laser illumination. Its dielectric permittivity and spontaneous polarization can be switched reversibly with a photoinduced phase transition triggered by structural photoisomerization between the enol form and the trans -keto form. To our knowledge, this is the first photoswitchable ferroelectric crystal to achieve polarization switching through a structural phase transition triggered by photoisomerization. This finding paves the way toward photocontrol of smart materials and biomechanical applications in the future.

With prosperity, decay, and another spring, molecular ferroelectrics have passed a hundred years since Valasek first discovered ferroelectricity in the molecular compound Rochelle salt. Recently, the proposal of ferroelectrochemistry has injected new vigor into this century-old research field. It should be highlighted that piezoresponse force microscopy (PFM) technique, as a non-destructive imaging and manipulation method for ferroelectric domains at the nanoscale, can significantly speed up the design rate of molecular ferroelectrics as well as enhance the ferroelectric and piezoelectric performances relying on domain engineering. Herein, we provide a brief review of the contribution of the PFM technique toward assisting the design and performance optimization of molecular ferroelectrics. Relying on the relationship between ferroelectric domains and crystallography, together with other physical characteristics such as domain switching and piezoelectricity, we believe that the PFM technique can be effectively applied to assist the design of high-performance molecular ferroelectrics equipped with multifunctionality, and thereby facilitate their practical utilization in optics, electronics, magnetics, thermotics, and mechanics among others.

Soil contamination and crop risks of heavy metal(loid)s are widely reported after the long-term irrigation of treated wastewater, causing an adverse influence on agricultural sustainability. Here, we collected soils after 50 years of wastewater irrigation to cultivate cabbage (Brassica pekinensis L.), rape (Brassica chinensis L.), carrots (Daucus carota L.), and potatoes (Solanum tuberosum L.), using surface and sprinkler irrigation with freshwater and wastewater. In general, we found the statistically insignificant influence of short-term freshwater irrigation on the soil and vegetable metal(loid) concentrations. Most of the vegetables had potential adverse health risks with the relatively lower risks in carrots and potatoes, and most of the risks were contributed by As and Cd. Nevertheless, we observed negligible health risks for all studied metal(loid)s in potatoes under the freshwater irrigations. Besides, compared to wastewater irrigations, freshwater irrigations produced lower Cd health risks in all four vegetable species. Sprinkler irrigation with freshwater was a favorable approach for reducing the uptake of metal(loid)s from soils and the metal(loid) concentrations in aboveground parts. Our study highlights the possibility of reducing vegetable metal(loid) risks in contaminated farmlands via a combined approach of coupling the short-term decrease in their levels in irrigation water with vegetable species selection., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Multiferroic materials have attracted great interest because of their underlying new science and promising applications in data storage and mutual control devices. However, they are still very rare and highly imperative to be developed. Here, we report an organic-inorganic hybrid perovskite trimethylchloromethylammonium chromium chloride (TMCM-CrCl 3 ), showing the coexistence of magnetic and electric orderings. It displays a paraelectric-ferroelectric phase transition at 397 K with an Aizu notation of 6/ mFm , and spin-canted antiferromagnetic ordering with a Néel temperature of 4.8 K. The ferroelectricity originates from the orientational ordering of TMCM cations, and the magnetism is from the [CrCl 3 ] - framework. Remarkably, TMCM-CrCl 3 is the first experimentally confirmed divalent Cr 2+ -based multiferroic material as far as we know. A new category of hybrid multiferroic materials is pointed out in this work, and more Cr 2+ -based multiferroic materials will be expectedly developed in the future., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Landfill refuse is a mixture of inorganic minerals and organic matter that is capable of undergoing complexation and redox reactions due to its active functional groups. Organic matter often combines with minerals in landfill refuse and it remains unclear whether this combination involves electron transfer. Therefore, the effects of landfill refuse composition on reductive dechlorination and speciation transformation of heavy metals were investigated in this study. Results show that landfill refuse comprises protein- and humic-like substances, aliphatic structures, and a large number of hydroxyl, carboxyl, quinoid and other active functional group. The electron donating capacity (0.09-0.26 μmol/g(C)) of landfill refuse was found to be higher than its electron accepting capacity (0.03-0.23 μmol/g(C)), indicating that electron donating groups (hydroxyl) were the main redox-active moieties, facilitating the reductive dechlorination of pentachlorophenol (PCP) by microorganism. Fe 2 O 3 , FeO and SiO 2 were the main inorganic minerals affecting PCP dechlorination. The speciation distribution of heavy metals in landfill refuse was determined by the BCR sequential extraction method. Results showed that Zn and Ni have high potential migration capacity, poor stability and the highest bioavailability, while Cr, Cu and Pb are relatively stable and have weak migration potential. The oxygen- and nitrogen-containing functional groups, aliphatic structures and aromatic carbon in landfill refuse can promote the transformation of Ni and Cr from an unstable to stable state. Protein-like substances exhibit a strong Cu binding ability, allowing Cu to combine with organic matter more easily than other assessed heavy metals. Both Fe 2 O 3 and FeO affected the stability of Cu. FeO promoted the stabilization of Zn, whereas Fe 2 O 3 and SiO 2 promoted Cu instability. These results could provide some references for the treatment of organic chlorides and the stabilization of heavy metals in landfill refuse in China., Competing Interests: Declaration of competing interest The authors declared that they have no any actual or potential conflict of interest to this work, including any financial, personal or other relationships with other people or organizations., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Organic ferroelectrics are attracting tremendous interest because of their mechanical flexibility, ease of fabrication, and low acoustical impedance. Although great advances have been made in recent years, topological defects such as vortices remain relatively unexplored in the organic ferroelectric system. Here, from [quinuclidinium]ReO 4 ([Q]ReO 4 ), we applied the molecular design strategy of H/F substitution to successfully synthesize the organic ferroelectric [4-fluoroquinuclidinium]ReO 4 ([4-F-Q]ReO 4 ). Through H/F substitution, the Curie temperature and spontaneous polarization are respectively increased from 367 K and 5.83 μC/cm 2 in [Q]ReO 4 to 466 K and 11.37 μC/cm 2 in [4-F-Q]ReO 4 . Moreover, under mechanical stress fields, three kinds of stripelike domains with various polarization directions emerge to form a windmill-like domain pattern in the thin film of [4-F-Q]ReO 4 , in which intriguing vortex-antivortex topological configurations can exist stably. This work provides an efficient strategy for optimizing the properties of organic ferroelectrics and exploring emergent phenomena.

Three-dimensional (3D) organic-inorganic lead halide hybrids have become a hot academic topic because of their various functional properties. However, 3D lead halide hybrid ferroelectrics are still very rare until now. Here, we report a new 3D lead halide perovskite-related ferroelectric, (EATMP)Pb 2 Br 6 [EATMP = (2-aminoethyl)trimethylphosphanium]. Based on nonferroelectric CH 3 NH 3 PbBr 3 , by replacing PbBr 6 octahedra with a Pb 2 Br 10 dimer of edge-sharing octahedra as the basic building unit, the expanded 3D lead bromide perovskite analog was formed with the large [EATMP] 2+ cations occupying the voids of framework. Notably, (EATMP)Pb 2 Br 6 displays a direct bandgap of 2.81 eV, four polarization directions, and a high Curie temperature ( T c ) of 518 K (much beyond that of BaTiO 3 , 393 K), which is the highest among all reported 3D organic-inorganic hybrid ferroelectrics. Such a high T c may result from the high rotational energy barrier of cations induced by a larger molecular volume and relatively low crystal symmetry. Our work provides an efficient avenue to construct new 3D organic-inorganic lead halide hybrids and would inspire the further exploration of 3D lead halide ferroelectrics.

A high transition temperature (T c ) is essential for the practical application of ferroelectrics as electronic devices under extreme thermal conditions in the aerospace, automotive, and energy industries. In recent decades, the isotope effect and strain engineering are found to effectively modulate T c ; however, these strategies are limited to certain systems. Developing simple, universal, and practical methods to improve T c has become an imminent challenge for expanding the applications of ferroelectrics. Here, by adopting a molecular design strategy involving H/F substitution on an organic-inorganic hybrid perovskite (1-azabicyclo[2.2.1]heptane)CdCl 3 at a T c of 190 K, the successful synthesis of a multiaxial, ferroelectric hybrid perovskite (4-fluoro-1-azabicyclo[2.2.1]heptane)CdCl 3 is reported, which demonstrates a large spontaneous polarization of 11.2 µC cm -2 (greater than that of polyvinylidene difluoride) and a T c of 419 K (greater than that of BaTiO 3 ). This temperature enhancement (229 K) is the largest reported for molecular ferroelectrics, far exceeding the reported enhancements induced by the isotope effect and other techniques. This pioneering technique provides an effective and universal method for improving T c in ferroelectrics and represents an important step toward the development of high-performance ferroelectric technology., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Topological defects such as vortices in ferroelectric materials are attracting tremendous interest because of their splendid possibilities for unique physical phenomena and potential applications in nanoelectronic devices. However, reports of the vortex structure have been scarce in organic ferroelectrics, which are highly desirable for their mechanical flexibility, easy and environment-friendly processing, and low acoustical impedance. Here, we successfully observed the robust triangular domains in a single-component organic ferroelectric, 2-(hydroxymethyl)-2-nitro-1,3-propanediol ( 1 ), six of which can form a 6-fold vertex domain structure. To our knowledge, it is the first time that such an intriguing topological vortex gets experimentally confirmed in ferroelectrics. Moreover, the symmetry change of 1 with an Aizu notation of m 3 m F1 leads to the most 48 crystallographically equivalent polarization directions among all ferroelectrics. With those benefits and excellent piezoelectric properties, compound 1 shows great potential as a reconfigurable electronic element or a mechanical sensor for soft robotics, flexible and wearable devices, and biomachines.

For a century ferroelectricity has attracted widespread interest from science and industry. Inorganic ferroelectric ceramics have dominated multibillion dollar industries of electronic ceramics, ranging from nonvolatile memories to piezoelectric sonar or ultrasonic transducers, whose polarization can be reoriented in multiple directions so that they can be used in the ceramic and thin-film forms. However, the realization of macroscopic ferroelectricity in the polycrystalline form is challenging for molecular ferroelectrics. In pursuit of low-cost, biocompatible, and mechanically flexible alternatives, the development of multiaxial molecular ferroelectrics is imminent. Here, from quinuclidinium perrhenate, we applied fluorine substitution to successfully design a multiaxial molecular ferroelectric, 3-fluoroquinuclidinium perrhenate ([3-F-Q]ReO 4 ), whose macroscopic ferroelectricity can be realized in both powder compaction and thin-film forms. The fluorination effect not only increases the intrinsic polarization but also reduces the coercive field strength. More importantly, it is also, as far as we know, the softest of all known molecular ferroelectrics, whose low Vickers hardness of 10.5 HV is comparable with that in poly(vinylidene difluoride) (PVDF) but almost 2 orders of magnitude lower than that in BaTiO 3 . These attributes make it an ideal candidate for flexible and wearable devices and biomechanical applications.

Organic-inorganic ABX 3 (A, B = cations, X = anion) hybrids with perovskite structure have recently attracted tremendous interest due to their structural tunability and rich functional properties, such as ferroelectricity. However, ABX 3 hybrid ferroelectrics with other structures have rarely been reported. Here, we successfully designed an ABX 3 hybrid ferroelectric [(CH 3 ) 3 NCH 2 F]ZnCl 3 with a spontaneous polarization of 4.8 μC/cm 2 by the molecular modification of [(CH 3 ) 4 N]ZnCl 3 through hydrogen/halogen substitution. It is the first zinc halide ABX 3 ferroelectric, which contains one-dimensional [ZnCl 3 ] - n chains of corner-sharing ZnCl 4 tetrahedra, distinct from the anionic framework of corner-sharing or face-sharing BX 6 octahedra in the ABX 3 perovskites. From zero dimension to one dimension, the high symmetry of ZnCl 4 tetrahedra is broken, and all of them align along one direction to form a polar [ZnCl 3 ] - n chain, beneficial to the generation of ferroelectricity. This finding provides an efficient polar anionic framework for enriching the family of hybrid ferroelectrics by assembling with various cations and should inspire further exploration of new classes of organic-inorganic ABX 3 ferroelectrics.

Topological defects, such as vortices and skyrmions, provide a wealth of splendid possibilities for new nanoscale devices because of their marvelous electronic, magnetic, and mechanical behaviors. Recently, great advances have been made in the study of the ferroelectric vortex in conventional perovskite oxides, such as BaTiO 3 and BiFeO 3 . Despite extensive interest, however, no intriguing ferroelectric vortex structures have yet been found in organic-inorganic hybrid perovskites (OIHPs), which are desirable for their mechanical flexibility, ease of fabrication, and low acoustical impedance. We observed the robust vortex-antivortex topological configurations in a two-dimensional (2D) layered OIHP ferroelectric (4,4-DFPD) 2 PbI 4 (4,4-DFPD is 4,4-difluoropiperidinium). This provides future directions for the study of perovskites and makes it a promising alternative for nanoscale ferroelectric devices in medical, micromechanical, and biomechanical applications.

The increasing quantities of insecticides that leach into water bodies severely affect the health of the aquatic environment. Juvenile hormone analogue (JHA) insecticides are endocrine disrupters that interfere with hormonal activity in insects by mimicking juvenile hormones (JHs). Because the structure and functions of methyl farnesoate in crustaceans are similar to the insect JHs, exogenous JHA insecticides may cause adverse effects on the growth and reproduction in crustaceans similar to those observed in insects. This study examined the toxic effects of two JHA insecticides, methoprene and fenoxycarb, on the water flea Moina macrocopa. The 24-h and 48-h LC 50 values for fenoxycarb and methoprene were 0.53 and 0.32 mg/L and 0.70 and 0.54 mg/L, respectively. Chronic exposure to the two JHAs caused a series of toxic effects in M. macrocopa, including shortening of life expectancy, repression of body growth, reduction in fecundity, and disturbed the expression of genes involved in the JH signaling pathway, in cuticle development, and in the carbohydrate, amino acid, and ATP metabolic processes. Moreover, JHA exposure impaired the growth and reproduction of the offspring of M. macrocopa exposed to JHAs, even when the neonates were not exposed to the chemicals. In addition, changes in the expression of genes related to histone methylation indicate that epigenetic changes may promote transgenerational impairment in M. macrocopa. These results demonstrate the toxic effects of fenoxycarb and methoprene on non-target aquatic organisms. The damages done by these JHA insecticides to the aquatic environment is worthy of our attention and further studies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Molecular ferroelectrics have attracted considerable interests because of their easy and environmentally friendly processing, low acoustical impedance and mechanical flexibility. Herein, a molecular thermochromic ferroelectric, N,N'-dimethyl-1,4-diazoniabicyclo[2.2.2]octonium tetrachlorocuprate(II) ([DMe-DABCO]CuCl 4 ) is reported, which shows both excellent ferroelectricity and intriguing thermochromism. [DMe-DABCO]CuCl 4 undergoes a ferroelectric phase transition from Pca2 1 to Pbcm at a significantly high Curie temperature of 413 K, accompanied by a color change from yellow to red that is due to the remarkable deformation of [CuCl 4 ] 2- tetrahedron, where the ferroelectric and paraelectric phases correspond to yellow and red, respectively. Combined with multiple bistable physical properties, [DMe-DABCO]CuCl 4 would be a promising candidate for next-generation smart devices, and should inspire further exploration of multifunctional molecular ferroelectrics., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Constructing a three-dimensional (3D) model through non-invasive techniques will greatly benefit the diagnosis and treatment of otitis media. However, such a model should reflect the physiological characteristics of the middle ear; in particular, the pressure-flow responses determine the validity of the model. Objectives: A 3D model of the middle ear was constructed by digital scanning and simulation. The pressure-flow properties in the model were measured to evaluate whether the model could reflect the real middle ear under physiological and pathological conditions. Materials and methods: Computed tomography (CT) scanning data from a healthy woman were input into Mimics 20.0 to construct 3D images of the middle ear. The 3D images were treated with Ansys 15.0 for finite element mesh generation. Msc Nastran 2014 were used for the fluid-solid coupling calculations. Results: The pressure-flow rate in the model resembled a Venturi tube, namely, the pressure decreased with increasing flow velocity, especially in the Eustachian tube. In the absence of the right mastoid process, the differences in air pressure and the maximal velocity in the model were reduced. Conclusions: This numerical model based on CT images of the middle ear recapitulates the biomechanical characteristics of the real middle ear. Significance: This study provides an easy and rapid approach to constructing a middle ear model for diagnosis and treatment of otitis media.

Molecular ferroelectrics are attracting tremendous interest because of their easy and environmentally friendly processing, light weight, low acoustical impedance, and mechanical flexibility, which are viable alternatives or supplements to conventional ceramic ferroelectrics. However, reports of ceramic-like molecular ferroelectrics that can be applied in the polycrystalline form have been scarce. Here, according to the "quasi-spherical theory", we successfully synthesized a ceramic-like molecular ferroelectric with an m 3 m F mm 2 type phase transition at 357 K, 1,5-diazabicyclo[3.2.1]octonium tetrafluoroborate ([3.2.1-dabco]BF 4 ), which can show excellent ferroelectric performance in the polycrystalline thin-film form at room temperature. On the basis of the reported molecular ferroelectric [2.2.2-dabco]BF 4 (2.2.2-dabco = 1,4-diazabicyclo[2.2.2]octonium) with an Aizu notation of 4/ mmm F mm 2 and two polar axes, we changed the [2.2.2-dabco] + cation to the [3.2.1-dabco] + cation to reduce the molecular symmetry and keep the quasi-spherical shape simultaneously, making the number of polar axes up to six. Moreover, the spontaneous polarization P s gets successfully increased from 4.9 μC cm -2 in [2.2.2-dabco]BF 4 to 5.5 μC cm -2 in [3.2.1-dabco]BF 4 . This precise molecular design strategy offers an efficient pathway to design ceramic-like molecular ferroelectrics.

Piezoelectric sensors that can work under various conditions with superior performance are highly desirable with the arrival of the Internet of Things. For practical applications, a large piezoelectric voltage coefficient g and a high Curie temperature T c are critical to the performance of piezoelectric sensors. Here, we report a two-dimensional perovskite ferroelectric (4-aminotetrahydropyran) 2 PbBr 4 [(ATHP) 2 PbBr 4 ] with a saturated polarization of 5.6 μC cm -2 , high T c of 503 K [above that of BaTiO 3 (BTO, 393 K)], and extremely large g 33 of 660.3 × 10 -3 V m N -1 [much beyond that of Pb(Zr,Ti)O 3 (PZT) ceramics (20 to 40 × 10 -3 V m N -1 ), more than 2 times higher than that of poly(vinylidene fluoride) (PVDF, about 286.7 × 10 -3 V m N -1 )]. Combined with the advantages of molecular ferroelectrics, such as light weight, easy and environmentally friendly processing, and mechanical flexibility, (ATHP) 2 PbBr 4 would be a competitive candidate for next-generation smart piezoelectric sensors in flexible devices, soft robotics, and biomedical devices.

Molecular ferroelectrics as alternatives to the conventional inorganic ferroelectrics have been greatly developed in past decades; many of these have been discovered and designed through various chemical means due to their structural adjustability. However, it is still a huge challenge to obtain high (above room temperature) Curie temperature ( T c ) molecular ferroelectrics to meet the application requirements. Here, we present a new organic-inorganic hybrid molecular ferroelectric, [cyclopentylammonium] 2 CdBr 4 ( 1 ), showing a moderate above-room-temperature T c of 340.3 K. The mechanism of the ferroelectric phase transition from Pnam to Pna 2 1 in 1 is ascribed to the order-disorder transition of both the organic cations and inorganic anions, affording a spontaneous polarization of 0.57 μC/cm 2 for the ferroelectric phase. Using piezoresponse force microscopy (PFM), we clearly observed the antiparallel 180° stripe domains and realized the polarization switching, unambiguously establishing the existence of room-temperature ferroelectricity in the thin film. These attributes make it attractive for use in flexible devices, soft robotics, biomedical devices, and other applications.

Since the first perovskite CaTiO 3 was discovered in 1839, the development of perovskite has a history of 180 years. The emergence of solar cells (CH 3 NH 3 )PbI 3 has set off the trend of hybrid organic-inorganic perovskite (HOIP) materials. Since then, various HOIPs have sprung up and been widely used in various material devices. Among them, HOIP ferroelectrics have gained widespread attention. However, antiperovskite, as a twin brother of perovskite, has been neglected although it has similar structure with perovskite. Here, we successfully found that [C 3 H 7 FN] 3 [SnCl 6 ]Cl has a three-dimensional (3D) antiperovskite structure with the formula M 3 AB. Importantly, the compound exhibits obvious ferroelectric properties with an Aizu notation of 622F6 at 391 K. To the best of our knowledge, this is the first 3D hybrid organic-inorganic antiperovskite ferroelectric, which will greatly promote the development of antiperovskite families with more superior physical properties., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hydrochars derived from municipal sewage sludge was analyzed for its feasibility for value-added recycling. Results of carbon content and elemental composition suggested that the hydrochars might not be comparable with pyrochars regarding to the carbon sequestration, long-term stability and fuel quality. Application as soil amendment would be a better approach for hydrochar utilization. To examine the potential benefits and risks of that, the total and available content of nutrients (i.e. N, P, and K) were measured, and the potentially toxic elements (PTEs, i.e. Zn, Cu, Pb, Ni and Cd) were analyzed for the total content, speciation, and leaching potential. Compared with pyrochars derived from the same feedstock, hydrochars had lower pH and higher cation exchange capacity. The available content of N (1.58-6.87 g/kg), P (0.270-0.901 g/kg), and K (0-0.873 g/kg) in the chars was less than the feedstock sludge (3.33 g/kg N, 3.02 g/kg P, 2.07 g/kg K), but still far higher than that of the agricultural soil (i.e. 0.014-0.488 g/kg N, 0.02 g/kg P, <0.1-0.272 g/kg). Remarkably, hydrochars showed better nutritional balance than pyrochars for its higher available K content. Risk of potentially toxic elements contamination by the sludge was efficiently reduced in either hydrochars or pyrochars, except the high leaching potential of Zn in pyrochars. Overall, in addition to the advantages of the hydrothermal carbonization process as energy saving and value-added liquid by-products, the hydrochars derived from sludge, with sufficient and balanced nutrients and limited PTEs pollution risk, can be a feasible and value-added material as soil amendment., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Two-dimensional (2D) organic-inorganic perovskites (OIPs), with improved material stability over their 3D counterparts, are highly desirable for device applications. It is their considerable structural diversity that offers an unprecedented opportunity to engineer materials with fine-tuning functionalities. The isosteric substitution of hydrogen by an electronegative fluorine atom has been proposed as a useful route to improve the photovoltaic performance of 2D OIPs, whereas its valuable role in developing ferroelectricity is still waiting for further exploration. Herein, for the first time we applied fluorinated aromatic cations in extending the family of 2D OIP ferroelectrics, and successfully obtained [2-fluorobenzylammonium] 2 PbCl 4 as a high-performance ferroelectric semiconductor. The failures in the nonferroelectric [4-fluorobenzylammonium] 2 PbCl 4 and [3-fluorobenzylammonium] 2 PbCl 4 demonstrate that the selective introduction of fluorine in correct structural positions is particularly essential. This work represents an unprecedented proof-of-concept in the use of fluorinated aromatic cations for the targeted design of excellent 2D OIP ferroelectrics, and is believed to inspire the future development of low-cost, high-efficiency, and stable device applications.

A host-guest inclusion compound, 18-crown-6 oxonium tetrachloride-gallium(iii), was shown to undergo a 4/mmmFmm2-type ferroelectric phase transition with four crystallographically equivalent polarization directions at 337 K. To the best of our knowledge, this is the first host-guest inclusion compound shown to be a high-temperature multiaxial molecular ferroelectric.

The significant Tc enhancement of 110 K in [N-fluoromethyldabconium] triiodide lead caused by the promising design of H/F substitution is the first and unprecedented, opening up an applicable and universal strategy to effectively regulate the Tc working temperature in phase transition materials.

Although the first ferroelectric discovered in 1920 is Rochelle salt, a typical molecular ferroelectric, the front-runners that have been extensively studied and widely used in diverse applications, such as memory elements, capacitors, sensors, and actuators, are inorganic ferroelectrics with excellent electrical, mechanical, and optical properties. With the increased concerns about the environment, energy, and cost, molecular ferroelectrics are becoming promising supplements for inorganic ferroelectrics. The unique advantages of high structural tunability and homochirality, which are unavailable in their inorganic counterparts, make molecular systems a good platform for manipulating ferroelectricity. Remarkably, based on the Neumann's principle and the Curie symmetry principle defining the group-to-subgroup relationship, we have found some outstanding high-temperature molecular ferroelectrics, like diisopropylammonium bromide (DIPAB) with a large spontaneous polarization up to 23 μC/cm 2 ( Fu, D. W.; et al. Science 2013 , 339 , 425 ). However, their application potential is severely limited by the uniaxial nature, leading to major issues in finding proper substrates for thin-film growth and achieving high thin-film performance. Inspired by the commercialized inorganic ferroelectrics like Pb(Zr, Ti)O 3 (PZT), where the multiaxial nature contributes greatly to the optimized ferroelectric and piezoelectric performance, developing high-temperature multiaxial molecular ferroelectrics is an imminent task. In this Account, we review our recent research progress on the targeted design of multiaxial molecular ferroelectrics. We first propose the "quasi-spherical theory", a phenomenological theory based on the Curie symmetry principle, to modify the spherical cations to a low-symmetric quasi-spherical geometry for acquiring the highly symmetric paraelectric phase and the polar ferroelectric phase of multiaxial ferroelectrics simultaneously. Besides the sizes and weights of the cation and anion, the intermolecular interactions are particularly crucial for decelerating the molecular rotation at low temperature to reasonably induce ferroelectricity. It means that the momentums of the cation and anion should be matched, so we describe the "momentum matching theory". In particular, introducing homochirality, a superiority of molecular materials over the inorganic ones, was demonstrated as an effective approach to increase the incidence of ferroelectric crystal structures. Thanks to the striking chemical variability and structure-property flexibility of molecular materials, our research efforts outlined in this Account have led to and will further motivate the richness and the application exploration of high-temperature, high-performance multiaxial molecular ferroelectrics, along with the implementation and perfection of the targeted design strategies.

A ferroelectric with a high phase-transition temperature (T c ) is an indispensable condition for practical applications. Over the past decades, both strain engineering and the isotope effect have been found to effectively improve the T c within ferroelectric material systems. However, the former strategy seems to prefer working in inorganic ferroelectric thin films, while the latter is also limited to some certain systems, such as hydrogen-bonded ferroelectrics. It is noted that a mono-fluorinated molecule is geometrically very similar to its parent molecule and the substitution of H by an F atom can introduce a chiral center on the molecule to template or stabilize polar structures. Significantly, the barrier of rotation of the fluorinated organic molecules is raised, resulting in a remarkable increase in T c . Herein, by applying the molecular design strategy of H/F substitution to the organic-inorganic perovskite ferroelectric (pyrrolidinium)CdCl 3 with a low T c of 240 K, two high-T c chiral perovskite ferroelectrics, (R)- and (S)-3-F-(pyrrolidinium)CdCl 3 are successfully synthesized, for which the T c reaches 303 K. The significant enhancement of 63 K in T c extends the ferroelectric working temperature range to room temperature. This finding provides a new effective way to regulate the T c in ferroelectrics and to design high-T c molecular ferroelectrics., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

2D organic-inorganic lead iodide perovskites have recently received tremendous attention as promising light absorbers for solar cells, due to their excellent optoelectronic properties, structural tunability, and environmental stability. However, although great efforts have been made, no 2D lead iodide perovskites have been discovered as ferroelectrics, in which the ferroelectricity may improve the photovoltaic performance. Here, by incorporating homochiral cations, 2D lead iodide perovskite ferroelectrics [R-1-(4-chlorophenyl)ethylammonium] 2 PbI 4 and [S-1-(4-chlorophenyl)ethylammonium] 2 PbI 4 are successfully obtained. The vibrational circular dichroism spectra and crystal structural analysis reveal their homochirality. They both crystalize in a polar space group P1 at room temperature, and undergo a 422F1 type ferroelectric phase transition with transition temperature as high as 483 and 473.2 K, respectively, showing a multiaxial ferroelectric nature. They also possess semiconductor characteristics with a direct bandgap of 2.34 eV. Nevertheless, their racemic analogue adopts a centrosymmetric space group P2 1 /c at room temperature, exhibiting no high-temperature phase transition. The homochirality in 2D lead iodide perovskites facilitates crystallization in polar space groups. This finding indicates an effective way to design high-performance 2D lead iodide perovskite ferroelectrics with great application prospects., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)