Direct detection of circularly polarized light (CPL) is a challenging task due to limited materials and ambiguous structure–property relationships that lead to low distinguishability of the light ...helicities. Perovskite ferroelectric semiconductors incorporating chirality provide new opportunities in dealing with this issue. Herein, a pair of 2D chiral perovskite ferroelectrics is reported, which have enhanced CPL detection performance due to interplays among lattice, photon, charge, spin, and orbit. The chirality‐transfer‐induced chiral&polar ferroelectric phase enhances the asymmetric nature of the photoactive sublattice and achieves a switchable self‐powered detection via the bulk photovoltaic effect. The single‐crystal‐based device exhibits a CPL‐sensitive detection performance under 430 nm with an asymmetric factor of 0.20 for left‐ and right‐CPL differentiation, about two times that of the pure chiral counterparts. The enhanced CPL detection performance is ascribed to the Rashba–Dresselhaus effect that originates from the bulk inversion asymmetry and strong spin–orbit coupling, shown with a large Rashba coefficient, which is demonstrated by density functional theory calculation and circularly polarized light excited photoluminescence measurement. These results provide new perspectives on chiral Rashba ferroelectric semiconductors for direct CPL detection and ferroelectrics‐based chiroptics and spintronics.
A pair of 2D chiral perovskite Rashba ferroelectric semiconductors is reported. The fabricated single‐crystal device responds to circularly polarized light (CPL) under 430 nm with an anisotropy factor of 0.20 for the left‐ and right‐CPL differentiation, about two times of reported pure chiral counterparts. The enhanced performance is ascribed to the Rashba–Dresselhaus effect with a large Rashba coefficient of 0.93 eV Å.
Hybrid metal halides (HMHs) based phase transition materials have received widespread attention due to their excellent performance and potential applications in energy harvesting, optoelectronics, ...ferroics, and actuators. Nevertheless, effectively regulating the properties of phase transitions is still a thorny problem. In this work, two chiral lead‐free HMHs (R‐3FP)2SbCl5 (1; 3FP=3‐fluoropyrrolidinium) and (R‐3FP)2SbBr5 (2) were synthesized. By replacing the halide ions in the inorganic skeleton, the phase transition temperature of 2 changes with an increase of about 20 K, compared with 1. Meanwhile, both compounds display reversible dielectric switching properties. Through crystal structure analysis and Hirshfeld surface analysis, their phase transitions are ascribed to the disorder of the cations and deformation of the inorganic chains.
This article reports a pair of 1D lead‐free hybrid metal halides: (R‐3FP)2SbCl5 (1; 3FP=3‐fluoropyrrolidinium) and (R‐3FP)2SbBr5 (2) exhibit high temperature triggered structural phase transition and dielectric switching properties. By halogen substitution in the inorganic framework, the dielectric switch temperature of 2 increased about 20 K, compared with 1.
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally, with >365,000 cases in California as of 17 July 2020. We ...investigated the genomic epidemiology of SARS-CoV-2 in Northern California from late January to mid-March 2020, using samples from 36 patients spanning nine counties and the Grand Princess cruise ship. Phylogenetic analyses revealed the cryptic introduction of at least seven different SARS-CoV-2 lineages into California, including epidemic WA1 strains associated with Washington state, with lack of a predominant lineage and limited transmission among communities. Lineages associated with outbreak clusters in two counties were defined by a single base substitution in the viral genome. These findings support contact tracing, social distancing, and travel restrictions to contain the spread of SARS-CoV-2 in California and other states.
Multiferroics refer to materials with two or more ferroic orders in one phase within a specific temperature range, including ferroelectricity, ferroelasticity, and ferromagnetism which have been ...widely used in sensors, actuators, and memory devices. Among them, hybrid perovskites exhibiting multiferroicity are generally limited to low dimensions (0D–2D). Designing 3D lead‐free perovskite multiferroics remains a challenge due to Goldschmidt's tolerance factor limitation. Here, a multiferroic perovskite (R‐3AP)RbBr3 (1; 3AP = 3‐ammoniopyrrolidinium) is successfully synthesized by introducing homochirality to the 3D ferroelectric (Rac‐3AP)RbBr3, achieving both ferroelasticity and ferroelectricity. Compound 1 undergoes a structure phase transition at 401 K belonging to Aizu notation 432F2(s), which has 12 ferroelectric equivalent polarization directions and 6 polar axes. Furthermore, 1 exhibits reversible second harmonic generation switching effects. Moreover, while the temperature varies, the reversible and rapid changes of ferroelastic domains in 1 are observed using a polarizing microscope, indicating that it is a ferroelastic material. This work provides a practical method for designing and synthesizing molecule‐based multiferroics.
The work reports a 3D perovskite multiferroics (R‐3AP)RbBr3 (1) based on the 3D rubidium‐based ferroelectric (Rac‐3AP)RbBr3 by using the homochirality strategy. Compound 1 exhibits 432F2(s) ferroelectric–ferroelastic phase transition at 401 K. In addition, 1 exhibits a second harmonic generation (SHG) switch and multi‐axis ferroelectricity with a saturation polarization (Ps) value of 1.21 µC·cm−2.
Abstract
Martensitic transformation, usually accompanied by ferroelastic and thermoelastic behaviors, is an interesting and useful mechanical-related property upon external stimuli. For molecular ...crystals, however, martensitic systems to show reversible stimuli-actuation behaviors are still limited because of a lack of designability and frequent crystal collapse due to large stress releases during the transformations. Here, a one-dimensional hybrid perovskite semiconductor (NMEA)PbI
3
(NMEA =
N
-methylethylammonium) was prepared by following a dimensionality reduction design principle. The crystal undergoes reversible ferroelastic and thermoelastic martensitic transformations, which are attributed to weak intermolecular interactions among the chains that easily trigger the interchain shearing movement. The actuation behavior occurring during the phase transition is very close to room temperature and demonstrated to behave as a mechanical actuator for switching. This work provides an effective approach to designing molecular actuators with promising applications in next-generation intelligence devices.
Abstract
Poor stability is a significant challenge to organic–inorganic hybrid perovskites for practical optoelectronic applications, which results from their inherent ionic nature and soft ...structures. The coordination bonding strategy is supposed to be a valid approach by enhancing the interaction between the cations and inorganic frameworks. Herein, the first pair of cation‐coordinated perovskites with high stability, achieved through coordination bonds between the cations and PbX
n
anions instead of the weak hydrogen bonds and van der Waals force presented in conventional ionic perovskites, is reported. In
L
/
R
‐(4HOPD)PbBr
3
(4HOPD = 4‐hydroxypiperidine cation) (L/R=Left/Right–handed), one of the six halogen atoms is replaced by an oxygen atom from the cation. The PbO bond contributes to the high stability under a double 85 test.
L
/
R
‐(4HOPD)PbBr
3
crystallizes in the tetragonal system, belonging to one of 11 enantiomorphic space group types,
P4
1
2
1
2
and
P4
3
2
1
2
. Similar to quartz, the chirality originates from the helical assembly of achiral units. The chirality‐induced optical rotatory power is 16.84° mm
−1
at 404 nm. Moreover, the uniaxial negative birefringent property with a comparable Δ
n
value makes it a good alternative to quartz. The remarkable stability of this new perovskite presents significant potential for further investigation into stable perovskites and their applications in optical rotation and polarizing optics.
Abstract Background In this study, we tested the hypothesis that a combined adipose-derived mesenchymal stem cell (ADMSC) and ADMSC-derived exosome therapy protected rat kidney from acute ...ischemia–reperfusion (IR) injury (i.e., ligation both renal arteries for 1 h and reperfusion for 72 h prior to euthanization). Methods and Results Adult-male SD rats (n = 40) were equally categorized into group 1 (sham control), group 2(IR), group 3IR + exosome (100 μg), group 4 IR + ADMSC (1.2 × 106 cells), and group 5 (IR-exosome-ADMSC). All therapies were performed at 3 h after IR procedure from venous administration. By 72 h, the creatinine level and kidney injury score were lowest in group 1 and highest in group 2, significantly higher in group 3 than in groups 4 and 5, and significantly higher in group 4 than in group 5 (all P < 0.0001). The protein expression of inflammatory (TNF-α/NF-κB/IL-1β/MIF/PAI-1/Cox-2), oxidative-stress (NOX-1/NOX-2/oxidized protein), apoptotic (Bax/caspase-3/PARP), and fibrotic (Smad3/TGF-β) biomarkers showed an identical pattern, whereas the anti-apoptotic (Smad1/5, BMP-2) and angiogenesis (CD31/vWF/angiopoietin) biomarkers and mitochondrial cytochrome-C showed an opposite pattern of creatinine level among the five groups (all P < 0.001). The microscopic findings of glomerular-damage (WT-1), renal tubular-damage (KIM-1), DNA-damage (γ-H2AX), inflammation (MPO/MIF/CD68) exhibited an identical pattern, whereas the podocyte components (podocin/p-cadherin/synaptopodin) displayed a reversed pattern of creatinine level (all P < 0.0001). Conclusion Combined exosome-ADMSC therapy was superior to either one for protecting kidney from acute IR injury.
Tuning phase transition temperature is one of the central issues in phase transition materials. Herein, we report a case study of using enantiomer fraction engineering as a promising strategy to tune ...the Curie temperature (T
) and related properties of ferroelectrics. A series of metal-halide perovskite ferroelectrics (S-3AMP)
(R-3AMP)
PbBr
was synthesized where 3AMP is the 3-(aminomethyl)piperidine divalent cation and enantiomer fraction x varies between 0 and 1 (0 and 1 = enantiomers; 0.5 = racemate). With the change of the enantiomer fraction, the T
, second-harmonic generation intensity, degree of circular polarization of photoluminescence, and photoluminescence intensity of the materials have been tuned. Particularly, when x = 0.70 - 1, a continuously linear tuning of the T
is achieved, showing a tunable temperature range of about 73 K. This strategy provides an effective means and insights for regulating the phase transition temperature and chiroptical properties of functional materials.
Blood pressure is maintained within a normal physiological range by a sophisticated regulatory mechanism. Baroreceptors serve as a frontline sensor to detect the change in blood pressure. Nerve ...signals are then sent to the cardiovascular control centre in the brain in order to stimulate baroreflex responses. Here, we identify TRPC5 channels as a mechanical sensor in aortic baroreceptors. In Trpc5 knockout mice, the pressure-induced action potential firings in the afferent nerve and the baroreflex-mediated heart rate reduction are attenuated. Telemetric measurements of blood pressure demonstrate that Trpc5 knockout mice display severe daily blood pressure fluctuation. Our results suggest that TRPC5 channels represent a key pressure transducer in the baroreceptors and play an important role in maintaining blood pressure stability. Because baroreceptor dysfunction contributes to a variety of cardiovascular diseases including hypertension, heart failure and myocardial infarction, our findings may have important future clinical implications.
Circular dichroism (CD) spectroscopy is a well-known and powerful technique widely used for distinguishing chiral enantiomers based on their differential absorbance of the right and left circularly ...polarized light. With the increasing demand for solid-state chiral optics, CD spectroscopy has been extended to elucidate the chirality of solid-state samples beyond the traditional solution state. However, due to the sample preparation differential, the CD spectra of the same compound measured by different researchers may not be mutually consistent. In this study, we employ solution, powder, thin-film, and single-crystal samples to explore the challenges associated with CD measurements and distinguish between genuine and fake signals. Rational fabrication of the solid-state samples can effectively minimize the macroscopic anisotropic nature of the samples and thereby mitigate the influence of linear dichroism (LD) and linear birefringence (LB) effects, which arise from anisotropy-induced differences in the absorbances and refractive indices. The local anisotropic and overall isotropic features of the high-quality thin-film sample achieve an optically isotropic state, which exhibits superior CD signal repeatability at the front and back sides at different angles by rotating the sample along the light path. In addition, sample thickness-induced CD signal overload and absorption saturation pose more severe challenges than the LBLD-induced amplified CD signal but are rarely focused on. The CD signal overload in the deep UV region leads to the presence of fake signals, while absorption saturation results in a complete loss of the CD signal. These findings help obtain accurate CD signals by a well-fabricated optically isotropic sample to avoid LDLB and optimize the sample thickness to avoid fake signals and no signals.
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