Dragonflies are excellent flyers among insects and their flight ability is closely related to the architecture and material properties of their wings. The veins are main structure components of a ...dragonfly wing, which are found to be connected by resilin with high elasticity at some joints. A three-dimensional (3D) finite element model of dragonfly wing considering the soft vein joints is developed, with some simplifications. Passive deformation under aerodynamic loads and active flapping motion of the wing are both studied. The functions of soft vein joints in dragonfly flight are concluded. In passive deformation, the chordwise flexibility is improved by soft vein joints and the wing is cambered under loads, increasing the action area with air. In active flapping, the wing rigidity in spanwise direction is maintained to achieve the required amplitude. As a result, both the passive deformation and the active control of flapping work well in dragonfly flight. The present study may also inspire the design of biomimetic Flapping Micro Air Vehicles (FMAVs).
Hybrid perovskite materials are famous for their great application potential in photovoltaics and optoelectronics. Among them, lead‐iodide‐based perovskites receive great attention because of their ...good optical absorption ability and excellent electrical transport properties. Although many believe the ferroelectric photovoltaic effect (FEPV) plays a crucial role for the high conversion efficiency, the ferroelectricity in CH3NH3PbI3 is still under debate, and obtaining ferroelectric lead iodide perovskites is still challenging. In order to avoid the randomness and blindness in the conventional method of searching for perovskite ferroelectrics, a design strategy of fluorine modification is developed. As a demonstration, a nonpolar lead iodide perovskite is modified and a new 2D fluorinated layered hybrid perovskite material of (4,4‐difluorocyclohexylammonium)2PbI4, 1, is obtained, which possesses clear ferroelectricity with controllable spontaneous polarization. The direct bandgap of 2.38 eV with strong photoluminescence also guarantees the direct observation of polarization‐induced FEPV. More importantly, the 2D structure and fluorination are also expected to achieve both good stability and charge transport properties. 1 is not only a 2D fluorinated lead iodide perovskite with confirmed ferroelectricity, but also a great platform for studying the effect of ferroelectricity and FEPV in the context of lead halide perovskite solar cells and other optoelectronic applications.
Through a design strategy of fluorine modification, a nonpolar lead iodide perovskite is modified and a new 2D fluorinated layered hybrid perovskite material of (4,4‐difluorocyclohexylammonium)2PbI4 is obtained, which possesses clear ferroelectricity with controllable spontaneous polarization and ferroelectric photovoltaic effect. The discovery of such a material provides a great platform for the fundamental study of lead halide perovskite solar cells and other optoelectronic applications.
Activated microglia can be polarized to the pro-inflammatory M1 phenotype and the anti-inflammatory M2 phenotype. Low-intensity pulsed ultrasound (LIPUS) can attenuate pro-inflammatory responses in ...activated microglia.
This study aimed to investigate the effects of LIPUS on M1/M2 polarization of microglial cells and the regulatory mechanisms associated with signaling pathways.
BV-2 microglial cells were stimulated by lipopolysaccharide (LPS) to an M1 phenotype or by interleukin-4 (IL-4) to an M2 phenotype. Some microglial cells were exposed to LIPUS, while others were not. M1/M2 marker mRNA and protein expression were measured using real-time polymerase chain reaction and western blot, respectively. Immunofluorescence staining was performed to determine inducible nitric oxide synthase (iNOS)-/arginase-1 (Arg-1)- and CD68-/CD206-positive cells.
LIPUS treatment significantly attenuated LPS-induced increases in inflammatory markers (iNOS, tumor necrosis factor-α, interleukin-1β, and interleukin-6) as well as the expression of cell surface markers (CD86 and CD68) of M1-polarized microglia. In contrast, LIPUS treatment significantly enhanced the expression of M2-related markers (Arg-1, IL-10, and Ym1) and membrane protein (CD206). LIPUS treatment prevented M1 polarization of microglia and enhanced or sustained M2 polarization by regulating M1/M2 polarization through the signal transducer and activator of transcription 1/STAT6/peroxisome proliferator-activated receptor gamma pathways.
Our findings suggest that LIPUS inhibits microglial polarization and switches microglia from the M1 to the M2 phenotype.
The X‐site ion in organic–inorganic hybrid ABX3 perovskites (OHPs) varies from halide ion to bridging linkers like HCOO−, N3−, NO2−, and CN−. However, no nitrite‐based OHP ferroelectrics have been ...reported so far. Now, based on non‐ferroelectric (CH3)4NNi(NO2)3, through the combined methodologies of quasi‐spherical shape, hydrogen bonding functionality, and H/F substitution, we have successfully synthesized an OHP ferroelectric, FMeTPNi(NO2)3 (FMeTP=N‐fluoromethyl tropine). As an unprecedented nitrite‐based OHP ferroelectric, the well‐designed FMeTPNi(NO2)3 undergoes the ferroelectric phase transition at 400 K with an Aizu notation of 6/mmmFm, showing multiaxial ferroelectric characteristics. This work is a great step towards not only enriching the molecular ferroelectric families but also accelerating the potential practical applications.
Through a combination of quasi‐spherical shape, hydrogen bonding functionality, and H/F substitution, a molecular perovskite ferroelectric was successfully synthesized, FMeTPNi(NO2)3 (FMeTP=N‐fluoromethyl tropine). As an unprecedented nitrite‐based molecular ferroelectric, it undergoes a ferroelectric phase transition at 400 K with an Aizu notation of 6/mmmFm, showing multiaxial characteristics.
Anatomizing mixed‐phases, referring to analyzing the mixing profiles and quantifying the phases’ proportions in a material, which is of great significance in the genuine applications. Here, by using ...second‐harmonic generation (SHG) polarimetry and piezoresponse force microscopy (PFM) techniques, this work elucidates the contributions and distributions of two different symmetric phases mixed in an archetype monoaxial molecular ferroelectric, diisopropylammonium chloride (DIPACl). The two competing phases are preferred in thermodynamics or kinetic process respectively, and this work evidences the switching behavior between the two competing phases facilitated by an external electrical field as opposed to a heating process. This research contributes novel insights into phase engineering in the field of molecular ferroelectrics and is poised to serve as a potent analytical tool for subsequent applications.
This study introduces an advanced molecular ferroelectric with amalgamation of two symmetric phases (phase α and phase γ). The mixing profile, as unveiled by Second Harmonic Generation (SHG) polarimetry, is predominantly at the nanoscale, as opposed to mixed grains. The transition process between the two symmetric phases is facilitated through the application of an external electrical field.
Background：Ossification of the ligamentum flavum （OLF） is being increasingly recognized as a cause of thoracic myelopathy.This study was to describe a rare clinical entity of spinal cord kinking （SK） ...in thoracic myelopathy secondary to OLF.Methods：The data of 95 patients with thoracic myelopathy secondary to OLF were analyzed retrospectively.The incidence and location of SK were determined using preoperative magnetic resonance imaging （MRI）.The clinical presentation and radiological characteristics in patients with SK were analyzed.Posterior en bloc laminectomy with OLF was performed,and the surgical results were evaluated.Results：SK was found in seven patients （7.4％） based on preoperative MRI.The patients included one male and six females with an average age of 55.6 years （range,48-64 years）.Five patients presented with radiculomyelopathy and two presented with typical thoracic myelopathy of spastic paraparesis.In all cases,the kinking was located just above the end of the spinal cord where the conus medullaris （CM） was compressed by the OLF.The degree of SK varied from mild to severe.The tip of the CM was located between the upper third of T1 1 to the lower third of L 1,above the lower edge of L 1.With an average follow-up of 30.4 months,the modified Japanese Orthopedic Association score significantly improved from 5.7 ± 1.8 preoperatively to 8.9 ± 1.4 postoperatively （t =12.05;P ＜ 0.0001） with an improvement rate of 63.1 ± 12.3％.Conclusions：SK is a rare radiological phenomenon.It is typically located at the thoracolumbar junction,where the CM is compressed by the OLF.Our findings indicate that these patients may benefit from a posterior decompressive procedure.
causes a variety of infectious diseases in various species of mammals and birds, resulting in enormous economic loss to the modern livestock and poultry industry. However, the mechanism of ...host-pathogen interaction is unclear. Here, we found that l-serine levels were significantly decreased in murine lungs infected with
Exogenous l-serine supplementation significantly increased the survival rate of mice and decreased the colonization of
in the lungs of mice. Notably, l-serine decreased the macrophage- and neutrophil-mediated inflammatory responses in mice during
infection.
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