Coupling Function Research Articles

Study on the water-carbon coupling coordination function on the eastern edge of the Qinghai-Tibet plateau

The Qilian Mountains on the eastern edge of the Tibetan Plateau are an important ecological security barrier in northwestern China and an extremely critical water-carbon conservation area. The water and carbon cycles are closely linked, and the water-carbon coupling process has become further complicated under global climate change and through the intensification of human activities. A better understanding of the impacts and potential mechanisms of water-carbon interactions is the key to improving the efficiency of water-carbon resource utilization. To rationalize the relationship between water and carbon, we used data from statistical almanacs, land use, DEM and various climatic elements to estimate the water-carbon nutrition in the Qilian Mountains from 2000 to 2020 based on the InVEST model and the Coupled Coordination Degree Model (CCDM) and to explore the coupling mechanism of water-carbon, spatial-temporal dynamics, and the influencing factors. The results showed that: 1). the average annual water and carbon storage in the Qilian Mountains are 63.21 × 108 m3 and 77.82 × 107 t, respectively, showing a spatial distribution pattern of high in the northeast and low in the southwest. The inter-annual changes in water (y=-0.451x+968.920) and carbon (y = 0.082x-87.808) showed different trends. 2). The annual average of the water-carbon coupling coordination degree of 0.280 in the Qilian Mountains was low in general, and the trends declined over time from 0.273 in 2000 to 0.264 in 2020. However, the spatial distribution was relatively clustered, and the spatial correlation improved from 0.69 in 2000 to 0.74 in 2020. 3). Precipitation, potential evapotranspiration and temperature were important elements driving water-carbon coupling. Among them, precipitation was significantly positively correlated with water-carbon coupling (r = 0.88), and potential evapotranspiration (r=-0.56) and temperature (r=-0.39) showed significant negative correlations with water-carbon coupling. This study can provide information for management and decision-making in carbon sequestration, water resource utilization, ecological protection and climate change, and promote the study of the spatial and temporal coupling functions of water and carbon with in the Qilian Mountains. Meanwhile, this study can provide a reference for the environmental management and protection of the Qilian Mountain ecosystem.

Inferring connectivity of an oscillatory network via the phase dynamics reconstruction

We review an approach for reconstructing oscillatory networks’ undirected and directed connectivity from data. The technique relies on inferring the phase dynamics model. The central assumption is that we observe the outputs of all network nodes. We distinguish between two cases. In the first one, the observed signals represent smooth oscillations, while in the second one, the data are pulse-like and can be viewed as point processes. For the first case, we discuss estimating the true phase from a scalar signal, exploiting the protophase-to-phase transformation. With the phases at hand, pairwise and triplet synchronization indices can characterize the undirected connectivity. Next, we demonstrate how to infer the general form of the coupling functions for two or three oscillators and how to use these functions to quantify the directional links. We proceed with a different treatment of networks with more than three nodes. We discuss the difference between the structural and effective phase connectivity that emerges due to high-order terms in the coupling functions. For the second case of point-process data, we use the instants of spikes to infer the phase dynamics model in the Winfree form directly. This way, we obtain the network’s coupling matrix in the first approximation in the coupling strength.

Euclidean Wormhole with k-essence field in the presence of Gauss–Bonnet term

In this paper, we present some analytical solutions of wormhole in four-dimensional Robertson–Walker Euclidean background considering Einstein–Gauss–Bonnet dilaton interaction with a [Formula: see text]-essence field for [Formula: see text]. The solutions are obtained assuming some restrictions on coupling function with a form of potential or with the ratio of kinetic to potential energy of the dilaton field. Euclidean wormhole, in one case, evolves through early transient inflationary era and after graceful exit from inflation, it asymptotically yields a radiation dominated era or a matter dominated era. In another solution, initial Euclidean wormhole is accompanied by oscillation of scale factor in Euclidean time at some late era which asymptotically yields exponential expansion. The violation of the null energy condition can be avoided asymptotically. The potential is also found to decay sharply.

Modeling the effect of multiple pests on ecosystem services provided by fruit crops: Application to apple

CONTEXTIn agroecosystems, crop pests have long been controlled by the intensive use of synthetic pesticides. To lower the dependency on pesticides, alternative crop protection strategies such as Integrated Pest Management (IPM) and Agroecological Crop Protection (ACP) have been proposed. In this context, it is crucial to consider multiple pests and their effects on host plant functioning and, ultimately, on system performance. OBJECTIVEWe aim to develop a pest-crop model to account for the effect of multiple pests on fruit tree functioning and the resulting ecosystem services provided by an orchard, using apple as a case study. METHODSFirst, we identified possible mechanisms of pest disturbance on apple tree for ten major pests: rosy and woolly apple aphid, codling, oriental and tortrix moths, red mite, powdery mildew, European canker, fire blight and apple scab. We classified them into seven functional groups: resource stealers, leaf area reducers, assimilation rate reducers, water transport reducers, assimilate sappers, fruit senescence accelerators and fruit marketability depreciators. Second, we defined coupling functions for each functional group. These describe the reduction of target variables in an existing fruit tree model (QualiTree), i.e. the variables to which the pest disturbances directly apply, as a function of pest abundances. Parameter values of the coupling functions were estimated based on the literature. Third, we used simulations in standard cultural conditions and a Monte Carlo Bayesian Sensitivity Analysis to test and hierarchize the effect of pests on the variation of nine indicators of four classes of ecosystem services (namely fruit production, climate regulation, soil nitrogen availability and water cycle maintenance and regulation).RESULTS AND CONCLUSIONSOnly four indicators were affected by the considered pests: refractometric index (measuring fruit sugar content), marketable yield, carbon sequestration and water drainage. The variations in refractometric index and in marketable yield were largely explained by the main effects of water transport reducers and fruit senescence accelerators, respectively. The latter also contributed the most to carbon sequestration variation. The variation in water drainage was largely explained by the main effect of mildew, an assimilation rate reducer. SIGNIFICANCEOur approach provides an operational tool to assess the impact of multiple pests on orchard ecosystem services. The model also opens up the possibility of studying the impact of pests in different ecological and technical contexts. For this, it must be coupled with models capable of predicting pest abundances as a function of cultivation practices and biotic and abiotic conditions.

Quasi-classical ground states. I. Linearly coupled Pauli–Fierz Hamiltonians

We consider a spinless, non-relativistic particle bound by an external potential and linearly coupled to a quantized radiation field. The energy \mathcal{E}(u,f) of product states of the form u\otimes\Psi_f , where u is a normalized state for the particle and \Psi_f is a coherent state in Fock space for the field, gives the energy of a Klein–Gordon–Schrödinger system. We minimize the functional \mathcal{E}(u,f) on its natural energy space. We prove the existence and uniqueness of a ground state under general conditions on the coupling function. In particular, neither an ultraviolet cutoff nor an infrared cutoff is imposed. Our results establish the convergence in the ultraviolet limit of both the ground state and ground state energy of the Klein–Gordon–Schrödinger energy functional, and provide the second-order asymptotic expansion of the ground state energy at small coupling.

Effects of inhaled seralutinib on right ventricular-pulmonary arterial (RV-PA) coupling and right heart function in pulmonary arterial hypertension (PAH)

Abstract Background Impaired RV-PA coupling portends a poor prognosis in PAH, and right ventricular free wall strain/systolic pulmonary artery pressure (RVFWS/sPAP) has been reported as a measure of RV-PA coupling. Furthermore, increased RVFWS and right atrial area (RAA), as well as decreased pulmonary artery compliance (PAC) are associated with increased mortality risk in PAH. Seralutinib is a novel, small molecule kinase inhibitor that targets PDGFR, CSF1R, and c-KIT administered via dry powder inhaler. TORREY, a phase 2, double-blind, randomised, placebo-controlled study of inhaled seralutinib in patients with PAH (NCT04456998) met its primary endpoint, demonstrating a significant reduction in pulmonary vascular resistance (PVR) from baseline (BL) to Week 24 compared to placebo. In addition, seralutinib significantly decreased NT-proBNP. Purpose To test the hypothesis that seralutinib would improve RVFWS/sPAP and other measures of right heart function after 24 weeks of treatment compared to placebo in the TORREY study. Methods Eighty-six patients with WHO Group 1 PH (Functional Class II, III), ages ≥18 years, pulmonary vascular resistance ≥400 dyne*s/cm5, and on stable PAH standard of care therapy (the majority of whom were on double and triple therapy with approved PAH medications) were enrolled. Right heart catheterisation (RHC) and full echocardiography were performed at BL and Week 24 and at BL, Week 12, and Week 24, respectively; both were analysed in a blinded central laboratory. To calculate RVFWS/sPAP, the pulmonary artery systolic pressure from RHC was used. PAC was calculated from RHC data with the formula (SV/(PAS-PAD)). Statistical analysis was performed using ANCOVA. Results At Week 24, the change in RVFWS/sPAP was lower in the seralutinib group compared to placebo (Table). The changes in RVFWS and RAA were lower in the seralutinib group vs placebo at Week 12 and Week 24 (Table). Change in NT-proBNP correlated with change in RAA (r = 0.43). At Week 24, change in PAC was greater in the seralutinib group (-0.02 ± 0.085 placebo, 0.19 ± 0.089 seralutinib; LSMD 0.22 (0.104) p = 0.04). There was no effect of seralutinib on left ventricular ejection fraction. Conclusion Treatment with seralutinib was associated with a significant reduction of RVFWS/sPAP. In addition, significant differences in RVFWS itself, RAA, and PAC were observed. These treatment effects support improved RV-PA coupling and right heart function. In conjunction with concordant reductions in PVR and NT-proBNP, these data suggest potential favourable effects of seralutinib in PAH. Seralutinib is in clinical development as a potential new treatment option for patients with PAH.

CaMKIIdelta-mediated SR Ca leak contributes to long-term Doxorubicin-induced cardiotoxicity

Abstract Background Cardiotoxicity represents a major complication of cancer therapy with anthracyclines, whose main known compound is doxorubicine (DOX). Although mechanisms of DOX-induced toxic cardiomyopathy (DICM) are not entirely understood, CaMKIIδ-activity is known to be increased upon acute DOX exposure, contributing to impaired Calcium (Ca) handling. However, currently no studies have addressed the question, whether CaMKIIδ is involved in DOX-induced long-term cardiotoxicity. Purpose We aimed to investigate cardiac function and intracellular Ca handling using an in-vivo DOX treated mouse model, examining whether CaMKIIδ is involved in DOX-induced long-term cardiotoxicity. Methods Cardiac function and excitation-contraction coupling of CaMKIIdWT and CaMKIId-/- (global CaMKIId knockout) mice were tested in an in-vivo DOX treated mouse model (cumulative dose 12 mg/kg, intraperitoneal injection). Cardiac function was determined by echocardiography after 12 weeks. Ca handling of freshly isolated cardiomyocytes was assessed by epifluorescence microscopy (Fura2-AM) and confocal microscopy (Fluo4-AM). Histological analyses regarding cardiac fibrosis and cell dimensions were examined. Results Long-term DOX exposure reduced left ventricular ejection fraction (EF) by ∼13% and markedly increased cardiac fibrosis in CaMKIIδWT mice. Moreover, CaMKIIdWT hearts displayed decreased cell volume indicating atrophy following DOX treatment. Coinciding with the reduction in EF, CaMKIIdWT mice showed depressed Ca transient amplitudes as well as slowed Ca transient decay indicating depressed Ca uptake into the sarcoplasmic reticulum (SR). In addition, spontaneous diastolic Ca leakage from the SR was dramatically increased. In contrast, CaMKIId-/- mice showed preserved EF following 12 weeks of DOX treatment as compared to CaMKIIdWT in line with maintained Ca transient amplitudes. As an underlying cause, SR Ca leakage was not increased in CaMKIId-/- myocytes despite DOX-treatment. Pharmacological CaMKII inhibition using AIP (1µM) prevented SR Ca leak and restored Ca transient amplitudes in DOX-treated CaMKIIdWT myocytes. Conclusion Our study shows that CaMKIId contributes to long-term DOX-induced cardiotoxicity. We found that chronic DOX treatment induced depressed cardiac function and myocardial fibrosis, associated with impaired calcium handling as a consequence of CaMKIId-mediated SR Ca leak, which was absent in our CaMKIId-/- mouse model. In line, pharmacological inhibition of CaMKII rescued impaired Ca handling in DOX-treated CaMKIIdWT myocytes.

Qp/Qs in ostium secundum atrial septal defect mitigates right ventricular dysfunction in patients with secondary pulmonary hypertension

Abstract Background Ostium-secundum atrial septal defect (OS-ASD) can potentially lead to pulmonary hypertension (PH) and associated right ventricle (RV) - pulmonary artery (PA) uncoupling. This, in turn, may eventually result in RV systolic dysfunction. Notwithstanding, whether the characteristics of the OS-ASD could mitigate this relationship is unclear. Purpose To evaluate a potential interaction of the OS-ASD shunt (Qp/Qs ratio) on the relationship with RV–PA coupling and RV systolic function in patients with secondary PH. Methods We designed a cross-sectional study of 63 adult patients with OS-ASD in which we performed a conventional transthoracic echocardiogram using Vivid 9X-clear equipment (GE Vingmed Ultrasound, Horten, Norway). We evaluated the OS-ASD shunt and other echocardiographic parameters, including the tricuspid annular plane systolic excursion (TAPSE), the systolic pulmonary artery pressure (sPAP) ratio and the right ventricular free wall longitudinal strain (RVFWLS). Polynomic adjusted correlations were performed to model the relationship between the TAPSE/sPAP ratio and the RVFWLS, then we evaluated an interaction effect of the OS-ASD shunt (Qp/Qs ratio), respectively adjusted for age, sex, body mass index, body surface area and right atrial area. Results In our study, 49 (78%) subjects were male, with a mean age of 41.8 (±15) years; 7.94% (n=5) had mild PH, 42.9% (n=27) had moderate PH and 49.2% (n=31) had severe PH. Mean echocardiographic parameters were: TAPSE 24.5 (±5.1) mm , sPAP of 55.9 (±20.7) mmHg, TAPSE/sPAP 0.49 (±0.2) mm/mmHg, RVFWLS -25.6 (±6.6) % and Qp/Qs 2.9 (±0.9). We observed a quadratic relationship between the TAPSE/sPAP ratio and the RVFWLS (r=0.691, p < 0.001; Figure 1). OS-ASD shunt had a positive interaction effect (β=10.9, 95% CI: 2.09-19.6, p=0.018) on the relationship between TAPSE/sPAP and RVFWLS after adjusting for covariates (Figure 2). Conclusions In conclusion, in patients with OS-ASD, the RV systolic function decreases as the RV-PA uncoupling increases, as reflected in the quadratic regression between the TAPSE/sPAP and the RVFWLS. Moreover, the increase in OS-ASD shunt decreases RVFWLS values in relationship to the TAPSE/sPAP ratio as observed in the interaction model. These results could suggest that the OS-ASD characteristics could potentially mitigate RV dysfunction in patients with secondary PH.Figure 1.Quadratic regressionFigure 2.Interaction model

Right ventricular-arterial coupling and exercise-induced tricuspid regurgitation

Abstract Background Right Ventricular-pulmonary Artery (RV-PA) coupling is prognostic in a variety of cardiovascular disorders, including heart failure with preserved ejection fraction, pulmonary hypertension and severe aortic stenosis. The functional aspects of RV-PA coupling are less investigated than rest ones especially in what is their interaction with tricuspid regurgitation (TR). Purpose We sought to understand the association of RV-PA coupling with extent of exercise induced TR by combining gas exchange abnormalities through cardiopulmonary exercise test (CPET) imaging. Methods We prospectively studied patients with indication to perform a CPET imaging test due to dyspnoea and underlying heart disease of any left ventricular ejection fraction. Demographics, baseline characteristics, echo and CPET parameters [(e.g. VE/VCO2 slope and peak oxygen consumption (pVO2)] were evaluated across 3 sub-cohorts phenotyped according to TR severity pattern at rest and at peak exercise . Mitral and tricuspid regurgitation degree were adjudicated accordingly to ESC guidelines. RV-PA coupling function was assessed through the ratio between tricuspid annular plane systolic excursion (TAPSE), and non-invasive pulmonary artery systolic pressure (PASP) with echocardiography. Dynamic TR was defined as detection of at least moderate TR grade from rest to stress. Results A total of 73 patients (age 67±13 years, 52% men), with a mean LVEF of 50±14% were studied. Overall 50 (69%) patients had less than moderate TR which did not increase during stress (Controls), 11 (15%) patients exhibited a dynamic TR pattern (Group 1), and 12 (16%) already had significant TR at rest (Group 2). TAPSE/PASP at rest and peak exercise were significantly lower in Group 1 and 2 compared to Controls (Figure), while the mean PAP/cardiac output (CO) ratio at rest and at peak exercise were significantly higher (Table). As to gas exchange data, Group 1 and 2 exhibited a lower median peak VO2, while Group 2 patients had also a higher median VE/VCO2 slope compared to Controls (Table). 10 (14%) patients showed at least moderate mitral regurgitation (significant MR) at rest and the prevalence of significant MR at peak was higher in group 1 and 2 compared to Controls (Table). A weak negative correlation was found between TAPSE/PASP slope and E/e’ ratio at peak exercise (r =-0.435, p<0.01). Conclusion In presence of exercise dyspnoea, patients with dynamic TR during maximal exercise exhibit a worse degree of RV-PA coupling and gas exchange profile compared to the group without significant exercise-induced TR. Moreover, the exercise-induced TR profile behaves similarly to the one of those presenting with moderate to severe TR already detectable at rest. Phenotyping dynamic TR and RV-PA warrants further evidence on therapies and outcomes prediction in exertional dyspnoea patients.FigureTable

Concentrating ground state for linearly coupled Schrödinger systems involving critical exponent cases

We study the following linearly coupled Schrödinger system:{−Δu+(μV1(x)+a)u=f(x)|u|p−2u+β(x)v,x∈RN,−Δv+(μV2(x)+b)v=g(x)|v|2⁎−2v+β(x)u,x∈RN, where N≥3,2<p≤2⁎, V1,V2∈C(RN,R+) are potential wells with bottoms Ωi=intVi−1(0), the parameters a>−λ1(Ω1),b>−λ1(Ω2) and λ1(Ωi) is the first eigenvalue of −Δ in H01(Ωi). Under some suitable assumptions on β(x) which relate to the potentials V1,V2 and the parameters a,b, the existence of positive ground states is obtained by variational method. Some interesting phenomena are that we relax the upper control condition of the coupling function β(x) and we do not need the weight function f(x) to be integrable or bounded in the subcritical case 2<p<2⁎. Moreover, from the concentration phenomenon of solutions, we obtain some results of the existence of positive ground states to a linearly coupled Schrödinger system in a bounded domain, which extend the recent results of Peng, et al. (2017), [25].

Abstract 17781: Spironolactone Improves Left Atrial Function and Atrioventricular Coupling in Resistant Hypertension

Purpose: To determine the blood pressure independent effects of spironolactone on left atrial (LA) size and function in patients with resistant hypertension (RHTN). Methods: Patients with RHTN (N=36, 55±7 years) were prospectively recruited. Spironolactone was initiated at 25 mg/day and increased to 50 mg/day after four weeks. Other antihypertensives were withdrawn to maintain constant blood pressure. Cardiac magnetic resonance imaging was performed at baseline and after six months of spironolactone treatment and changes in LA functional metrics were assessed (Figure 1). The statistical analysis was conducted using two-sided tests of significance. Results: LA size and function parameters improved from baseline to month-six: LA volumes indexed to body surface area (LAVI) were reduced (LAVI max 41.4±12 vs 33.2±9.7 ml/m 2 ; LAVI pre-A 32.6±9.8 vs 25.6±8.1 ml/m 2 ; LAVI min 18.5 [13.9 - 24.8] vs 14.1 [10.9 - 19.2] ml/m 2 ; all p &lt; 0.05); left atrioventricular coupling index was reduced (28.2±11.5 vs 22.7±9.2 %, p &lt; 0.05); LA emptying fractions (LAEF) were increased (total LAEF 52.4 [48.7 - 60.3] vs 55.9 [50.3 - 61.1] %; active LAEF 40.2±8.6 vs 43.1±7.8 %, both p &lt; 0.05). There was a substantial increase in reservoir strain (29.1 ± 8.5 % vs 30.9 ± 5.5 %, p = 0.068) whereas active strain was significantly increased from baseline (16.3 ± 4.1 % vs 17.8 ± 4.2 %, p &lt; 0.05). Changes in passive strain and strain rates were not statistically significant (p &gt; 0.1). The effect of spironolactone was similar in patients with high (N = 18) and normal (N = 18) aldosterone status (defined by plasma renin activity and 24-hour urine aldosterone). Conclusion: Treatment of RHTN with spironolactone is associated with improvements in LA size and function regardless of whether aldosterone levels were normal or high. This study suggests the need for larger prospective studies examining effects of mineralocorticoid receptor antagonists on atrial function and atrioventricular coupling.

Abstract 109: Nitric Oxide Added to the ECMO Circuit Improves Neuroprotection and Cardiac Function After Cardiac Arrest

Background: Veno-arterial extracorporeal life support (ECLS) is increasingly used in patients during cardiac arrest. Nitric Oxide (NO) has shown potential for exerting a protective role in ischemia/reperfusion damage in different organs. Aim: This study aims to investigate the cardio and neuroprotective effects of NO administered in the extracorporeal membrane oxygenation (ECMO) circuit after cardiac arrest. Methods: Thirty male SD rats were subjected to 10 minutes of cardiac arrest. They were randomly assigned to receive ECMO or ECMO plus NO (20 ppm) administered in the oxygenator (ECMO+NO). After 1 hour, the animals were weaned from ECMO, hemodynamic analysis using pressure-volume miniaturized catheter, and cardiac and brain samples were collected after two hours. Results: Analysis of cardiac function showed improved systolic cardiac function in the ECMO+NO group compared to standard ECMO (stroke volume: 55 ± 8 vs. 26 ± 9 μl, cardiac index: 9.05 ± 1.41 vs. 4.70 ± 0.81 ml/min/100g, dP/dt max : 6870 ± 290 vs. 5124 ± 205 mmHg/s; p&lt;0.01). The ECMO+NO group also exhibited reduced systemic resistance (total peripheral resistance: 2.14 ± 0.42 vs. 2.95 ± 0.35 mmHg/ml/min/100g; p&lt;0.05) and improved ventricular-arterial coupling (Ees/Ea: 0.96 ± 0.15 vs. 0.53 ± 0.15; p&lt;0.001). Neuroinflammation, assessed by the expression of Iba1, a microglia activation marker, was attenuated in the ECMO+NO group (8.37 ± 0.41% vs. 12.58 ± 0.48%; p &lt; 0.001). The extent of hypoxic brain areas, analyzed by thiol oxidation, was lower in the ECMO+NO group (4.07 ± 0.45% vs. 11.72 ± 1.03%; p&lt;0.01). Conclusions: NO administration in the oxygenator during ECMO after cardiac arrest improves cardiac function and ventricular-arterial coupling and enhances neuroprotection decreasing neuroinflammation and hypoxic areas. NO administration in the ECMO circuit might be a promising therapeutic adjunct during ECLS.

Synergetic Coupling of Redox-Active Sites on Organic Electrode Material for Robust and High-Performance Sodium-Ion Storage.

Organic electrode materials (OEMs), valued for their sustainability and structural tunability, have been attracting increasing attention for wide application in sodium-ion batteries (SIBs) and other rechargeable batteries. However, most OEMs are plagued with insufficient specific capacity or poor cycling stability. Therefore, it's imperative to enhance their specific capacity and cycling stability through molecular design. Herein, we designed and synthesized a heteroaromatic molecule 2,3,8,9,14,15-hexanol hexaazatrinaphthalene (HATN-6OH) by the synergetic coupling of catechol (the precursor of ortho-quinone)/ortho-quinone functional groups and HATN conjugated core structures. The abundance of catechol/ortho-quinone and imine redox-active moieties delivers a high specific capacity of nine-electron transfer for SIBs. Most notably, the π-π interactions and intermolecular hydrogen bond forces among HATN-6OH molecules secure the stable long-term cycling performance of SIBs. Consequently, the as-prepared HATN-6OH electrode exhibited a high specific capacity (554 mAh g-1 at 0.1 A g-1 ), excellent rate capability (202 mAh g-1 at 10 A g-1 ), and stable long-term cycling performance (73 % after 3000 cycles at 10 A g-1 ) in SIBs. Additionally, the nine-electron transfer mechanism is confirmed by systematic density functional theory (DFT) calculation, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and Raman analysis. The achievement of the synergetic coupling of the redox-active sites on OEMs could be an important key to the enhancement of SIBs and other metal-ion batteries.

Synergetic Coupling of Redox‐Active Sites on Organic Electrode Material for Robust and High‐Performance Sodium‐Ion Storage

AbstractOrganic electrode materials (OEMs), valued for their sustainability and structural tunability, have been attracting increasing attention for wide application in sodium‐ion batteries (SIBs) and other rechargeable batteries. However, most OEMs are plagued with insufficient specific capacity or poor cycling stability. Therefore, it′s imperative to enhance their specific capacity and cycling stability through molecular design. Herein, we designed and synthesized a heteroaromatic molecule 2,3,8,9,14,15‐hexanol hexaazatrinaphthalene (HATN‐6OH) by the synergetic coupling of catechol (the precursor of ortho‐quinone)/ortho‐quinone functional groups and HATN conjugated core structures. The abundance of catechol/ortho‐quinone and imine redox‐active moieties delivers a high specific capacity of nine‐electron transfer for SIBs. Most notably, the π–π interactions and intermolecular hydrogen bond forces among HATN‐6OH molecules secure the stable long‐term cycling performance of SIBs. Consequently, the as‐prepared HATN‐6OH electrode exhibited a high specific capacity (554 mAh g−1 at 0.1 A g−1), excellent rate capability (202 mAh g−1 at 10 A g−1), and stable long‐term cycling performance (73 % after 3000 cycles at 10 A g−1) in SIBs. Additionally, the nine‐electron transfer mechanism is confirmed by systematic density functional theory (DFT) calculation, attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR), and Raman analysis. The achievement of the synergetic coupling of the redox‐active sites on OEMs could be an important key to the enhancement of SIBs and other metal‐ion batteries.

Study on Kalb–Ramond field localization in f(T) gravity theory with a noncanonical scalar field

In this paper, we investigate the localization of five-dimensional tensor gauge fields called Kalb–Ramond fields in the modified teleparallel braneworld models. The aforementioned branes are generated by gravity coupled to a real scalar field with nonstandard kinetic terms. For two specific forms of the noncanonical expressions, background scalar field solutions are particularly discussed in the presence of different forms of [Formula: see text] gravity. By applying nonminimal coupling functions in the tensor gauge field action, it is shown that massless zero modes of Kalb–Ramond gauge fields can be localized on the [Formula: see text] branes with noncanonical scalar fields. We also find that potentials of Kalb–Ramond massive modes are volcano-like regarding the equation of motion in the supersymmetric quantum mechanic scenario. Furthermore, the effects of parameters that control the deviation of the usual teleparallel theory are considered on the massless Kaluza–Klein mode and effective potential.

Atomically precise ultrasmall copper cluster for room-temperature highly regioselective dehydrogenative coupling

Three-component dehydrogenative coupling reactions represent important and practical methodologies for forging new C–N bonds and C–C bonds. Achieving highly all-in-one dehydrogenative coupling functionalization by a single catalytic system remains a great challenge. Herein, we develop a rigid-flexible-coupled copper cluster [Cu3(NHC)3(PF6)3] (Cu3NC(NHC)) using a tridentate N-heterocyclic carbene ligand. The shell ligand endows Cu3NC(NHC) with dual attributes, including rigidity and flexibility, to improve activity and stability. The Cu3NC(NHC) is applied to catalyze both highly all-in-one dehydrogenative coupling transformations. Mechanistic studies and density functional theory illustrate that the improved regioselectivity is derived from the low energy of ion pair with copper acetylide and endo-iminium ions and the low transition state, which originates from the unique physicochemical properties of the Cu3NC(NHC) catalyst. This work highlights the importance of N-heterocyclic carbene in the modification of copper clusters, providing a new design rule to protect cluster catalytic centers and enhance catalysis.

Modulation of sarcopenia phenotypes by glutathione peroxidase 4 overexpression in mice.

Our laboratory previously showed lipid hydroperoxides and oxylipin levels are elevated in response to loss of skeletal muscle innervation and are associated with muscle pathologies. To elucidate the pathological impact of lipid hydroperoxides, we overexpressed glutathione peroxidase 4 (GPx4), an enzyme that targets reduction of lipid hydroperoxides in membranes, in adult CuZn superoxide dismutase knockout (Sod1KO) mice that show accelerated muscle atrophy associated with loss of innervation. The gastrocnemius muscle from Sod1KO mice shows reduced mitochondrial respiration and elevated oxidative stress (F2 -isoprostanes and hydroperoxides) compared to wild-type (WT) mice. Overexpression of GPx4 improved mitochondrial respiration and reduced hydroperoxide generation in Sod1KO mice, but did not attenuate the muscle loss that occurs in Sod1KO mice. In contrast, contractile force generation is reduced in EDL muscle in Sod1KO mice relative to WT mice, and overexpression of GPx4 restored force generation to WT levels in Sod1KO mice. GPx4 overexpression also prevented loss of muscle contractility at the single fibre level in fast-twitch fibres from Sod1KO mice. Muscle fibres from Sod1KO mice were less sensitive to both depolarization and calcium at the single fibre level and exhibited a reduced activation by S-glutathionylation. GPx4 overexpression in Sod1KO mice rescued the deficits in both membrane excitability and calcium sensitivity of fast-twitch muscle fibres. Overexpression of GPx4 also restored the sarco/endoplasmic reticulum Ca2+ -ATPase activity in Sod1KO gastrocnemius muscles. These data suggest that GPx4 plays an important role in preserving excitation-contraction coupling function and Ca2+ homeostasis, and in maintaining muscle and mitochondrial function in oxidative stress-induced sarcopenia. KEY POINTS: Knockout of CuZn superoxide dismutase (Sod1KO) induces elevated oxidative stress with accelerated muscle atrophy and weakness. Glutathione peroxidase 4 (GPx4) plays a fundamental role in the reduction of lipid hydroperoxides in membranes, and overexpression of GPx4 improves mitochondrial respiration and reduces hydroperoxide generation in Sod1KO mice. Muscle contractile function deficits in Sod1KO mice are alleviated by the overexpression of GPx4. GPx4 overexpression in Sod1KO mice rescues the impaired muscle membrane excitability of fast-twitch muscle fibres and improves their calcium sensitivity. Sarco/endoplasmic reticulum Ca2+ -ATPase activity in Sod1KO muscles is decreased, and it is restored by the overexpression of GPx4. Our results confirm that GPx4 plays an important role in preserving excitation-contraction coupling function and Ca2+ homeostasis, and maintaining muscle and mitochondrial function in oxidative stress-induced sarcopenia.

Hybrid coupling rules for leaderless heterogeneous oscillators: Uniform global asymptotic and finite-time synchronization

We investigate the engineering scenario where the objective is to synchronize heterogeneous oscillators in a distributed fashion. The internal dynamics of each oscillator are general enough to capture their time-varying natural frequency as well as physical couplings and unknown bounded terms. A communication layer is set in place to allow the oscillators to exchange synchronizing coupling actions through a tree-like leaderless network. In particular, we present a class of hybrid coupling rules depending only on local information to ensure uniform global practical or asymptotic synchronization, which is impossible to obtain by using the Kuramoto model customarily used in the literature. We further show that the synchronization set can be made uniformly globally prescribed finite-time stable by selecting the coupling function to be discontinuous at the origin. Novel mathematical tools on non-pathological functions and set-valued Lie derivatives are developed to carry out the stability analysis. The effectiveness of the approach is illustrated in simulations where we apply our synchronizing hybrid coupling rules to models of power grids previously used in the literature.

Passivity and underactuated modeling-based load energy coupling control for three-dimensional overhead crane systems

The conventional control strategies and methods with the three-dimensional model of overhead crane system are excessively dependent on model parameters and lead to the controllers design complex on position and anti-swing of overhead crane systems. With analysis on the coupling relationship among various state variables of overhead crane, the three-dimensional dynamic model of overhead crane based on mechanical virtual displacement and Lagrangian equation is constructed. A novel control strategy based on load energy coupling is designed to realize system positioning and eliminate the problem of residual load swing. The passivity of the three-dimensional overhead crane system is judged, and the energy composition of the system is deduced. The energy coupling function based on load displacement and swing angle is built. The control strategy of three-dimensional overhead crane system based on load energy coupling is designed by the Lyapunov stability theory and function construction method. The stability of the system is verified by the Lasalle invariance principle. With the experimental and programming, the proposed method is compared with different control methods. The results show that this method can realize the accurate positioning of the trolley more quickly and restrain the load swing more effectively.

A shape parameter insensitive CRBFs‐collocation for solving nonlinear optimal control problems

AbstractIn this work, we introduce a Coupled Radial Basis Functions collocation (CRBFs‐Coll) approach for solving optimal control problems. CRBFs are real‐valued Radial Basis Functions (RBFs) augmented with a conical spline. They show insensitivity to the shape parameter resulting in robust behavior in function approximation. The method is applied to classical nonlinear optimal control problems: Zermelo's problem, a Duffing oscillator with various boundary conditions, and a nonlinear pendulum on a cart problem. The nonlinear optimal control problem is solved by deriving the necessary conditions for optimality followed by collocation using CRBFs as basis functions for approximating the two‐point boundary value problem (TPBVP). The resulting system of nonlinear algebraic equations (NAEs) is then solved using a standard solver. Unlike existing methods that rely on nodal distributions that are denser at the boundaries to obtain a solution, the present CRBFs‐Coll approach is capable of solving the optimal control problem on uniform nodes without the need for interpolation. The present CRBFs‐Coll approach is shown to be simple to implement and provides accurate results over an equidistant nodal distribution while maintaining a continuous representation of the control and states.