Spinal sensory transmission is under descending biphasic modulation, and descending facilitation is believed to contribute to chronic pain. Descending modulation from the brainstem rostral ...ventromedial medulla (RVM) has been the most studied, whereas little is known about direct corticospinal modulation. Here, we found that stimulation in the anterior cingulate cortex (ACC) potentiated spinal excitatory synaptic transmission and this modulation is independent of the RVM. Peripheral nerve injury enhanced the spinal synaptic transmission and occluded the ACC-spinal cord facilitation. Inhibition of ACC reduced the enhanced spinal synaptic transmission caused by nerve injury. Finally, using optogenetics, we showed that selective activation of ACC-spinal cord projecting neurons caused behavioral pain sensitization, while inhibiting the projection induced analgesic effects. Our results provide strong evidence that ACC stimulation facilitates spinal sensory excitatory transmission by a RVM-independent manner, and that such top-down facilitation may contribute to the process of chronic neuropathic pain.
Highly selective and direct electroreductive ring‐opening carboxylation of epoxides with CO2 in an undivided cell is reported. This reaction shows broad substrate scopes within styrene oxides under ...mild conditions, providing practical and scalable access to important synthetic intermediate β‐hydroxy acids. Mechanistic studies show that CO2 functions not only as a carboxylative reagent in this reaction but also as a promoter to enable efficient and chemoselective transformation of epoxides under additive‐free electrochemical conditions. Cathodically generated α‐radical and α‐carbanion intermediates lead to the regioselective formation of α‐carboxylation products.
Highly selective and direct electroreductive ring‐opening carboxylation of epoxides with CO2 in an undivided cell to yield synthetically important β‐hydroxy acids is described. CO2 functions not only as a carboxylative reagent in this reaction but also as a promoter to enable efficient and chemoselective transformation of epoxides under additive‐free electrochemical conditions.
Fe‐based oxides have been seldom reported as electrocatalysts for the hydrogen evolution reaction (HER), limited by their weak intrinsic activity and conductivity. Herein, phosphorus doping ...modulation is used to construct inverse spinel P‐Fe3O4 with dual active sites supported on iron foam (P‐Fe3O4/IF) for alkaline HER with an extremely low overpotential of 138 mV at 100 mA cm−2. The obtained inverse spinel Fe–O–P derived from controllable phosphorization can provide an octahedral Fe site and O atom, which bring about the unusual dissociation mechanisms of two water molecules to greatly accelerate the proton supply in alkaline media. Meanwhile, the ΔGH of the P atom in Fe–O–P as an active site is theoretically calculated to be 0.01 eV. Notably, the NiFe LDH/IF(+)||P‐Fe3O4/IF(−) couple achieves an onset potential of 1.47 V (vs RHE) for overall water splitting, with excellent stability for more than 1000 h at a current density of 1000 mA cm−2, and even for 25 000 s at 10 000 mA cm−2 in 6.0 m KOH at 60 °C. The excellent catalyst stability and low‐cost merits of P‐Fe3O4/IF may hold promise for industrial hydrogen production. This work may reveal a new design strategy of earth‐abundant materials for large‐scale water splitting.
The octahedral Fe and O in inverse spinel Fe–O–P bring about the unusual dissociation mechanisms of two water molecules for accelerating proton supply. The ΔGH of the P atom in Fe–O–P as an active site is theoretically proved to be 0.01 eV. Therefore, phosphorus doping modulation is a promising strategy for excellent electrocatalysts for hydrogen evolution reaction.
Broadband tuning of polarization states is pivotal yet challenging in modern photonics technologies, especially for miniaturized or integrated systems. Metasurfaces potentially provide an effective ...approach to resolve this challenge. However, once a metadevice is fabricated, its functionalities are determined, and it is hard to actively tune the polarization states. Here, the electrically tunable broadband polarization states by combining phase‐change material (vanadium dioxide) and dispersion‐free metasurface are demonstrated for the first time. The polarization states are modulated through the electrically driven, Joule‐heat‐induced phase transition of vanadium dioxide, where the output polarization state can be continuously tuned from horizontal one to vertical one, or from circular polarization to linear polarization. With accurate on‐chip control of the phase transition, continuous and reversible modulation of polarization is verified in a scanning display. Moreover, a proof‐of‐concept demonstration for dynamically independent control of multiple polarization display is carried out. Different images are produced by applying electrical currents in N separate channels to generate a dynamic multiplexing polarization display with 2N encoding states. Such an active metasurface can be readily integrated with electronics and has potential applications in display, encryption, camouflage, and information processing.
Electrically driven tunable broadband polarization states are demonstrated by combining vanadium dioxide and dispersion‐free metasurface. The polarization states of reflected light can be continuously modulated from horizontal polarization to perpendicular polarization or from circular polarization to linear polarization through the electrically tuned phase transition of vanadium dioxide. Such an active metasurface can be applied in display, encryption, and information processing.
Plasmonic color filtering and color printing have attracted considerable attention in recent years due to their supreme performance in display and imaging technologies. Although various color‐related ...devices are designed, so far very few studies have touched the topic of dynamic color generation. In this article, dynamic color generation is demonstrated by integrating plasmonic nanostructures with vanadium dioxide based on its tunable optical properties through insulator–metal transition. Periodic arrays of silver nanodisks on a vanadium dioxide film are fabricated to realize different colors, relying on the excitation of localized and propagating surface plasmons, and Wood's anomaly. By tuning spatial periodicity of the arrays and diameter of the silver nanodisks, various colors can be achieved across the entire visible spectrum. Further, using insulator–metal transition of vanadium dioxide, the colors can be actively tuned by varying temperature. The approach of dynamic color generation based on the phase transition of vanadium dioxide can easily realize diverse color patterns, which makes it beneficial for display and imaging technology with distinct advantages of multifunctionality, flexibility, and high efficiency.
Dynamic color generation is realized by integrating plasmonic nanostructures with vanadium dioxide based on its tunable optical properties through insulator–metal transition. Various colors can be designed across the visible spectrum via adjusting the spatial periodicity and nanodisk diameter of the silver‐nanodisk array, and the colors can be tuned dynamically by varying the temperature.
Oxytocin is a well-known neurohypophysial hormone that plays an important role in behavioral anxiety and nociception. Two major forms of long-term potentiation, presynaptic LTP (pre-LTP) and ...postsynaptic LTP (post-LTP), have been characterized in the anterior cingulate cortex (ACC). Both pre-LTP and post-LTP contribute to chronic-pain-related anxiety and behavioral sensitization. The roles of oxytocin in the ACC have not been studied. Here, we find that microinjections of oxytocin into the ACC attenuate nociceptive responses and anxiety-like behavioral responses in animals with neuropathic pain. Application of oxytocin selectively blocks the maintenance of pre-LTP but not post-LTP. In addition, oxytocin enhances inhibitory transmission and excites ACC interneurons. Similar results are obtained by using selective optical stimulation of oxytocin-containing projecting terminals in the ACC in animals with neuropathic pain. Our results demonstrate that oxytocin acts on central synapses and reduces chronic-pain-induced anxiety by reducing pre-LTP.
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•Oxytocin microinjected into ACC attenuates injury-related pain and anxiety responses•Oxytocin blocks the maintenance of pre-LTP, but not post-LTP•Oxytocin depolarizes the interneurons and decreases the ratio of E/I transmission•Activation of PVN-ACC pathway blocks pre-LTP and has analgesic and anxiolytic effects
Li et al. report that microinjection of oxytocin into the ACC attenuates nerve-injury-induced nociceptive and anxiety behavioral responses. They show that oxytocin blocks the maintenance of pre-LTP and potentiates inhibitory transmission. Optical activation of endogenous oxytocin release in the ACC blocks pre-LTP and produces analgesic and anxiolytic effects.
Herein we report an efficient strategy for preparing isotactic polyesters and chiral epoxides via enantioselective resolution copolymerization of racemic terminal epoxides with anhydrides, mediated ...by enantiopure bimetallic complexes in conjunction with a nucleophilic cocatalyst. The chirality of both the axial linker and the diamine backbones of the ligand are responsible for the chiral induction of this kinetic resolution copolymerization process. The catalyst systems exhibit exceptional levels of enantioselectivity with a kinetic resolution coefficient exceeding 300 for various racemic epoxides, affording highly isotactic copolymers (selectivity factors of more than 300) with a completely alternating structure and low polydispersity index. Most of the produced isotactic polyesters are typical semicrystalline materials with melting temperatures in the range from 77 to 160 °C.
Lymphocyte-to-monocyte ratio (LMR) is associated with diverse malignancies and cardiovascular diseases. However, it has not yet been identified whether LMR is correlated with stroke severity and ...prognosis. We aimed to explore the relationship between LMR and stroke severity, prognosis, and the predictive value of LMR on a 3-month functional outcome in patients with acute ischemic stroke (AIS).
A total of 512 patients were enrolled in this study. Baseline demographic and clinical data of all patients were collected. Based on the LMR value on admission (>4.83, 2.97-4.83, <2.97), patients were divided into 3 groups. Moderate to severe stroke was defined as a National Institutes of Health Stroke Scale score of 6 or higher. Poor outcome was defined as a modified Rankin Scale score of 3 or higher. We used the Spearman rank correlation to evaluate the relationship between LMR and stroke severity. Binary logistic regression analysis was used to assess risk factors of stroke severity and prognosis. The receiver operating characteristic (ROC) curve was used to estimate the predictive value of LMR on prognosis.
LMR was inversely correlated with stroke severity (r = −.014, P = .019). Moreover, LMR was an independent protective factor of stroke severity (odds ratio OR .891, 95% confidence interval CI .815-.973, P = .010) and prognosis (OR .507, 95% CI .437-.590, P < .001). ROC indicated that an LMR lower than 2.99 predicted a poor outcome, with a sensitivity of 69.3% and a specificity of 86.6%.
A lower LMR on admission was independently associated with severe stroke and 3-month poor outcome in patients with AIS.
Calcium phosphate-based mineralo-organic particles form spontaneously in the body and may represent precursors of ectopic calcification. We have shown earlier that these particles induce activation ...of caspase-1 and secretion of IL-1β by macrophages. However, whether the particles may produce other effects on immune cells is unclear. Here, we show that these particles induce the release of neutrophil extracellular traps (NETs) in a size-dependent manner by human neutrophils. Intracellular production of reactive oxygen species is required for particle-induced NET release by neutrophils. NETs contain the high-mobility group protein B1 (HMGB1), a DNA-binding protein capable of inducing secretion of TNF-α by a monocyte/macrophage cell line and primary macrophages. HMGB1 functions as a ligand of Toll-like receptors 2 and 4 on macrophages, leading to activation of the MyD88 pathway and TNF-α production. Furthermore, HMGB1 is critical to activate the particle-induced pro-inflammatory cascade in the peritoneum of mice. These results indicate that mineral particles promote pro-inflammatory responses by engaging neutrophils and macrophages via signaling of danger signals through NETs.
Unprecedented enantioselective resolution copolymerization of racemic cis‐internal epoxides and anhydrides was mediated by dinuclear aluminum complexes with multiple chirality, affording optically ...active polyesters with two contiguous stereogenic centers, and the unreacted substrates in good enantioselectivity. Unexpected stereoconvergence is observed in this resolution copolymerization, where the selectivity factor for the enantioselective formation of copolymer significantly exceeds the kinetic resolution coefficient based on the unreacted epoxide at various conversions. Catalytic activity and copolymer enantioselectivity are strongly influenced by the phenolate ortho‐substituents of the ligand set, as well as the axial linker and its chirality. An enantiopure binaphthol‐linked bimetallic AlIII complex allows stereoconvergent access to the stereoregular semi‐crystalline polyesters and a concomitant kinetic resolution of the epoxide substrates.
Stereoconvergence is observed in the enantioselective resolution copolymerization of racemic cis‐internal epoxides and anhydrides mediated by dinuclear aluminum complexes with multiple chirality, where the selectivity factor for chiral copolymer formation significantly exceeds the kinetic resolution coefficient based on the unreacted substrate at various conversions.
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