Observation of Ferromagnetism in Dilute Magnetic Halide Perovskite Semiconductors.

Dilute magnetic semiconductors (DMSs) have attracted much attention because of their potential use in spintronic devices. Here, we demonstrate the observation of robust ferromagnetism in a solution-processable halide perovskite semiconductor with dilute magnetic ions. By codoping of magnetic (Fe2+) and aliovalent (Bi3+) metal ions into CH3NH3PbCl3 (MAPbCl3) perovskite, ferromagnetism with well-saturated magnetic hysteresis loops and a maximum coercivity field of 1280 Oe was observed below 12 K. The ferromagnetic resonance measurements revealed that the incorporation of aliovalent ions modulates the carrier concentration and plays an essential role in realizing the ferromagnetism in dilute magnetic halide perovskites. Magnetic ions are proposed to interact through itinerant charge carriers to achieve ferromagnetic coupling. Our work provides a new avenue for the development of solution-processable magnetic semiconductors.

Improved ion adsorption capacities and diffusion dynamics in surface anchored MoS2⊥Mo4/3B2 and MoS2⊥Mo4/3B2O2 heterostructures as anodes for alkaline metal-ion batteries.

First-principles calculations were performed to analyze the atomic structures and electrochemical energy storage properties of novel MoS2⊥boridene heterostructures by anchoring MoS2 nanoflakes on Mo4/3B2 and Mo4/3B2O2 monolayers. Both thermodynamic and thermal stabilities of each heterostructure were thoroughly evaluated from the obtained binding energies and through first-principles molecular dynamics simulations at room temperature, confirming the high formability of the heterostructures. The electrochemical properties of MoS2⊥Mo4/3B2 and MoS2⊥Mo4/3B2O2 heterostructures were investigated for their potential use as anodes for alkaline metal ion batteries (Li+, Na+ and K+). It was revealed that Li+ and Na+ can form multiple stable full adsorption layers on both heterostructures, while K+ forms only a single full adsorption layer. The presence of a negative electron cloud (NEC) contributes to the stabilization of a multi-layer adsorption mechanism. For all investigated alkaline metal ions, the predicted ion diffusion dynamics are relatively sluggish for the adsorbates in the first full adsorption layer on MoS2⊥boridene heterostructures due the relatively large migration energies (>0.50 eV), compared to those of second or third full adsorption layers (<0.30 eV). MoS2⊥Mo4/3B2O2 exhibited higher onset and mean open circuit voltages as anodes for alkaline metal-ion batteries than MoS2⊥Mo4/3B2 hybrids because of enhanced interactions between the adsorbate and the Mo4/3B2O2 monolayer with the presence of O-terminations. Tailoring the size and horizontal spacing between two neighboring MoS2 nano-flakes in heterostructures led to high theoretical capacities for LIBs (531 mA h g-1), SIBs (300 mA h g-1) and PIBs (131 mA h g-1) in the current study.

Assessing r2SCAN meta-GGA functional for structural parameters, cohesive energy, mechanical modulus, and thermophysical properties of 3d, 4d, and 5d transition metals.

The recent development of accurate and efficient semilocal density functionals on the third rung of Jacob's ladder of density functional theory, such as the revised regularized strongly constrained and appropriately normed (r2SCAN) density functional, could enable rapid and highly reliable prediction of the elasticity and temperature dependence of thermophysical parameters of refractory elements and their intermetallic compounds using the quasi-harmonic approximation (QHA). Here, we present a comparative evaluation of equilibrium cell volumes, cohesive energy, mechanical moduli, and thermophysical properties (Debye temperature and thermal expansion coefficient) for 22 transition metals using semilocal density functionals, including the local density approximation (LDA), Perdew-Burke-Ernzerhof (PBE) and PBEsol generalized gradient approximations (GGAs), and the r2SCAN meta-GGA. PBEsol and r2SCAN deliver the same level of accuracies for structural, mechanical, and thermophysical properties. PBE and r2SCAN perform better than LDA and PBEsol for calculating cohesive energies of transition metals. Among the tested density functionals, r2SCAN provides an overall well-balanced performance for reliably computing cell volumes, cohesive energies, mechanical properties, and thermophysical properties of various 3d, 4d, and 5d transition metals using QHA. Therefore, we recommend that r2SCAN could be employed as a workhorse method to evaluate thermophysical properties of transition metal compounds and alloys in high throughput workflows.

Negatively Curved Octagon-Incorporated Aza-nanographene and its Assembly with Fullerenes.

A negatively curved aza-nanographene (NG) containing two octagons was synthesized by a regioselective and stepwise cyclodehydrogenation procedure, in which a double aza[7]helicene was simultaneously formed as an intermediate. Their saddle-shaped structures with negative curvature were unambiguously confirmed by X-ray crystallography, thereby enabling the exploration of the structure-property relationship by photophysical, electrochemical and conformational studies. Moreover, the assembly of the octagon-embedded aza-NG with fullerenes was probed by fluorescence spectral titration, with record-high binding constants (Ka=9.5×103 M-1 with C60, Ka=3.7×104 M-1 with C70) found among reported negatively curved polycyclic aromatic compounds. The tight association of aza-NG with C60 was further elucidated by X-ray diffraction analysis of their co-crystal, which showed the formation of a 1 : 1 complex with substantial concave-convex interactions.

Controlling the Emissive, Chiroptical, and Electrochemical Properties of Double [7] Helicenes through Embedded Aromatic Rings.

We present here the synthesis and in-depth physicochemical characterization of a double hetero[7]helicene fused with four triazole rings at both helical ends. The comparison of this triazole-fused double helicene with the previously reported all-carbon and thiadiazole-fused analogs revealed the huge impact of the embedded aromatic rings on the photophysical features. The small structural variation of the terminal rings from thiadiazole to triazole caused a dramatic change of the photoluminescence quantum yields (PLQYs) from <1 % to 96 %, while the replacement of the terminal benzene rings with triazole rings induced a tenfold enhancement of the circularly polarized luminescence dissymmetry factor. These observations were well corroborated with transient absorption analysis and/or theoretic calculations. In addition, the triazole-fused double helicene exhibited ambipolar redox behavior, enabling the generation of radical cation and anion species by electrochemical and chemical methods and showing its potential for spin-related applications.

Truncated Face-Rotating Polyhedra Constructed from Pentagonal Pentaphenylpyrrole through Graph Theory.

Discovering novel families of molecular polyhedra through graph theory has attracted increasing interest. Nevertheless, the design principles of molecular polyhedra based on graph theory remain elusive, especially for those containing five-node units. Herein, we construct a series of chiral truncated face-rotating polyhedra (T-FRP) from pentagonal pentaphenylpyrrole (PPP) derivatives and chiral diamines. Graph theory is used to elucidate the geometry of these novel T-FRP, which represent a new family of molecular polyhedra. The phenyl flipping of PPP faces in these T-FRP is significantly restricted, thus making T-FRP chiral and strongly emissive in solution. In addition, T-FRP also generate circularly polarized luminescence. This study provides new insights into the rational design of novel molecular polyhedra through graph theory.

Separation of Spin and Charge Transport in Pristine π-Conjugated Polymers.

We have experimentally tested whether spin-transport and charge-transport in pristine π-conjugated polymer films at room temperature occur via the same electronic processes. We have obtained the spin diffusion coefficient of several π-conjugated polymer films from the spin diffusion length measured by the technique of inverse spin Hall effect and the spin relaxation time measured by pulsed electrically detected magnetic resonance spectroscopy. The charge diffusion coefficient was obtained from the time-of-flight mobility measurements on the same films. We found that the spin diffusion coefficient is larger than the charge diffusion coefficient by about 1-2 orders of magnitude and conclude that spin and charge transports in disordered polymer films occur through different electronic processes.

Magneto-electroluminescence response in 2D and 3D hybrid organic-inorganic perovskite light emitting diodes.

We have studied the magneto-electroluminescence (MEL) response in light emitting diodes based on 2D-(PEA)2PbI4 and 3D-MAPbI3 hybrid organic-inorganic perovskites at cryogenic temperatures. We found that the MEL is negative, i.e., the EL decreases with the applied field strength, B. In addition, the MEL(B) response has a Lorentzian line shape whose width depends on the perovskite used. We interpret the MEL(B) response using the "Δg mechanism" in which the spin of the injected electron-hole (e-h) pairs oscillates between singlet and triplet configurations due to different precession frequencies of the electron and hole constituents that originate from the difference, Δg, in the electron and hole gyromagnetic constants, g. In this model, the MEL(B) linewidth is inversely proportional to the spin lifetime and Δg. The model used is validated by directly measuring the spin lifetime of photogenerated e-h pairs using the circularly polarized pump-probe transmission technique with 100 fs resolution.

Organic-based magnon spintronics.

Magnonics concepts utilize spin-wave quanta (magnons) for information transmission, processing and storage. To convert information carried by magnons into an electric signal promises compatibility of magnonic devices with conventional electronic devices, that is, magnon spintronics 1 . Magnons in inorganic materials have been studied widely with respect to their generation2,3, transport4,5 and detection 6 . In contrast, resonant spin waves in the room-temperature organic-based ferrimagnet vanadium tetracyanoethylene (V(TCNE) x (x ≈ 2)), were detected only recently 7 . Herein we report room-temperature coherent magnon generation, transport and detection in films and devices based on V(TCNE) x using three different techniques, which include broadband ferromagnetic resonance (FMR), Brillouin light scattering (BLS) and spin pumping into a Pt adjacent layer. V(TCNE) x can be grown as neat films on a large variety of substrates, and it exhibits extremely low Gilbert damping comparable to that in yttrium iron garnet. Our studies establish an alternative use for organic-based magnets, which, because of their synthetic versatility, may substantially enrich the field of magnon spintronics.

Triindolo-Truxene Derivatives: Design, Synthesis, and Fine-Tuning of Electronic Properties and Molecular Assembly through Molecular Engineering.

Triindolo-truxene, a C3 -symmetric molecule with a large π-conjugated plane, has six methylene carbon atoms and three aromatic carbon atoms that can be facilely functionalized. Herein, butyl, carbonyl, cyano, and/or malononitrile groups were introduced at six methylene carbon atoms (6-, 14-, 22- or 8-, 16-, 24-positions) and/or three aromatic carbon atoms (2-, 10-, and 18-positions) of triindolo-truxene to produce eight derivatives. Their photophysical properties, electrochemical properties, and molecular assembly can be effectively modulated by substituents and substitution patterns. Incorporation of electron-deficient groups led to redshifts in both the absorption and emission of these derivatives and also lowered their HOMO and LUMO levels. Different substitution patterns resulted in the different intramolecular donor-acceptor interactions. Electron-deficient substituents at the methylene carbon atoms in the 6-, 14-, and 22-positions led to intramolecular charge transfer from the fluorene arms to the truxene core, whereas the corresponding substitutions at the methylene carbon atoms in the 8-, 16-, and 24-positions resulted in intramolecular charge transfer from the truxene core to the fluorene arms. The molecular packing in single crystals and molecular aggregation in solution are also influenced by the substituents and substitution patterns. This work provides a straightforward strategy to alter the properties of triindolo-truxene.

Surface-enhanced spin current to charge current conversion efficiency in CH3NH3PbBr3-based devices.

Hybrid organic-inorganic perovskites have shown great promise for spintronic applications due to their large spin-orbit coupling induced by the Pb and halogen atoms. Particularly, the large observed surface-induced Rashba splitting in CH3NH3PbBr3 indicates efficient spin-current-to-charge-current (StC) conversion, which, however, has not been demonstrated yet. In this work, the StC conversion efficiency in ferromagnet/CH3NH3PbBr3-based devices is studied using the pulsed spin-pumping technique measured by the inverse spin Hall effect. We found that the StC conversion efficiency is anomalous in that it increases at small perovskite layer thickness. This indicates the existence of a surface-dominated StC mechanism such as the inverse Rashba-Edelstein effect. By inserting a thin LiF layer between the ferromagnet and the perovskite film, the StC conversion efficiency is greatly suppressed, validating the existence of a Rashba surface in the CH3NH3PbBr3 film.

Topological Insulator-Based van der Waals Heterostructures for Effective Control of Massless and Massive Dirac Fermions.

Three dimensional (3D) topological insulators (TIs) are an important class of materials with applications in electronics, spintronics and quantum computing. With the recent development of truly bulk insulating 3D TIs, it has become possible to realize surface dominated phenomena in electrical transport measurements e.g. the quantum Hall (QH) effect of massless Dirac fermions in topological surface states (TSS). However, to realize more advanced devices and phenomena, there is a need for a platform to tune the TSS or modify them e.g. gap them by proximity with magnetic insulators, in a clean manner. Here we introduce van der Waals (vdW) heterostructures in the form of topological insulator/insulator/graphite to effectively control chemical potential of the TSS. Two types of gate dielectrics, normal insulator hexagonal boron nitride (hBN) and ferromagnetic insulator Cr2Ge2Te6 (CGT) are utilized to tune charge density of TSS in the quaternary TI BiSbTeSe2. hBN/graphite gating in the QH regime shows improved quantization of TSS by suppression of magnetoconductivity of massless Dirac fermions. CGT/graphite gating of massive Dirac fermions in the QH regime yields half-quantized Hall conductance steps and a measure of the Dirac gap. Our work shows the promise of the vdW platform in creating advanced high-quality TI-based devices.

Lateral Magnetically Modulated Multilayers by Combining Ion Implantation and Lithography.

The combination of lithography and ion implantation is demonstrated to be a suitable method to prepare lateral multilayers. A laterally, compositionally, and magnetically modulated microscale pattern consisting of alternating Co (1.6 µm wide) and Co-CoO (2.4 µm wide) lines has been obtained by oxygen ion implantation into a lithographically masked Au-sandwiched Co thin film. Magnetoresistance along the lines (i.e., current and applied magnetic field are parallel to the lines) reveals an effective positive giant magnetoresistance (GMR) behavior at room temperature. Conversely, anisotropic magnetoresistance and GMR contributions are distinguished at low temperature (i.e., 10 K) since the O-implanted areas become exchange coupled. This planar GMR is principally ascribed to the spatial modulation of coercivity in a spring-magnet-type configuration, which results in 180° Néel extrinsic domain walls at the Co/Co-CoO interfaces. The versatility, in terms of pattern size, morphology, and composition adjustment, of this method offers a unique route to fabricate planar systems for, among others, spintronic research and applications.

Creating coordination-based cavities in a multiresponsive supramolecular gel.

Creating cavities in varying levels, from molecular containers to macroscopic materials of porosity, have long been motivated for biomimetic or practical applications. Herein, we report an assembly approach to multiresponsive supramolecular gels by integrating photochromic metal-organic cages as predefined building units into the supramolecular gel skeleton, providing a new approach to create cavities in gels. Formation of discrete O-Pd2 L4 cages is driven by coordination between Pd(2+) and a photochromic dithienylethene bispyridine ligand (O-PyFDTE). In the presence of suitable solvents (DMSO or MeCN/DMSO), the O-Pd2 L4 cage molecules aggregate to form nanoparticles, which are further interconnected through supramolecular interactions to form a three-dimensional (3D) gel matrix to trap a large amount of solvent molecules. Light-induced phase and structural transformations readily occur owing to the reversible photochromic open-ring/closed-ring isomeric conversion of the cage units upon UV/visible light radiation. Furthermore, such Pd2 L4 cage-based gels show multiple reversible gel-solution transitions when thermal-, photo-, or mechanical stimuli are applied. Such supramolecular gels consisting of porous molecules may be developed as a new type of porous materials with different features from porous solids.

HnRNPA1 Prevents Endothelial-to-mesenchymal Transition-induced VSMC Activation and Neointimal Hyperplasia in Vein Grafts.

Endothelial-to-mesenchymal transition (EndoMT) is associated with neointimal hyperplasia and vein graft failure, and heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) has emerged as a major modulator of EMT. We aimed to investigate the functional consequence of EndoMT in neointimal hyperplasia and the precise role of hnRNPA1 in the regulation of EndoMT and neointimal hyperplasia. We investigated the spatial and temporal distribution characteristics of EndoMT cells in a mouse model of vein graft transplantation. In vitro, we studied the interaction between EndoMT cells and VSMCs, and the underlying mechanism was investigated by cytokine antibody assays. In cultured HUVECs, we studied the effect of hnRNPA1 on EndoMT and the cellular interactions by using siRNA-mediated knockdown and adenovirus-mediated overexpression. We further investigated the role of hnRNPA1 in EndoMT and neointimal hyperplasia in vivo with an AAV-mediated EC-specific hnRNPA1 overexpression murine model. We demonstrated the presence of EndoMT cells during the initial stage of neointimal formation, and that EndoMT cells promoted the proliferation and migration of VSMCs in vitro. Mechanistic studies revealed that EndoMT cells express and secrete a higher level of PDGF-B. Furthermore, we found a regulatory role for hnRNPA1 in EndoMT in vitro and in vivo. Similarly, we found that hnRNPA1 overexpression in ECs reduced the expression and secretion of PDGF-B during EndoMT, effectively inhibiting EndoMT cell-mediated activation of VSMCs in vitro and neointimal formation in vivo. Taken together, these findings indicate that EndoMT cells can activate VSMCs through a paracrine mechanism mediated by hnRNPA1 and lead to neointimal hyperplasia.

Fast access of the lattice thermal conductivity and phonon quasiparticle spectra of Mo2TiC2T2 (T = -O and -F) and Janus Mo2TiC2OF MXenes from machine learning potentials.

The presence of strong anharmonic effects in surface functionalized MXenes greatly challenges the use of harmonic lattice dynamics calculations to predict their phonon spectra and lattice thermal conductivity at finite temperatures. Herein, we demonstrate the workflow for training and validating machine learning potentials in terms of moment tensor potential (MTP) for MXenes including Mo2TiC2, Mo2TiC2O2, Mo2TiC2F2 and Janus-Mo2TiC2OF monolayers. Then, the MTPs of MXenes are successfully combined with the harmonic lattice dynamics calculations to obtain the temperature renormalized phonon spectra, three-phonon scattering rates, phonon relaxation times and lattice thermal conductivity at finite temperatures. Furthermore, combining MTPs with classic molecular dynamics simulations at finite temperatures directly enables the calculation of phonon quasi-particle spectral energy density with a full inclusion of all anharmonic effects in MXenes. Our current results indicate that anharmonic effects are found to be relatively weak in Mo2TiC2 and Mo2TiC2O2 monolayers, whereas the phonon quasi-particle spectral energy densities largely resemble those of harmonic or renormalized lattice dynamics calculations. Significant broadening of spectral energy density at finite temperature is predicted for Mo2TiC2F2 and Janus-Mo2TiC2OF monolayers, implying strong anharmonic effects in those MXenes. Our work paves a new way for fast and reliable calculation of the phonon scattering process and lattice thermal conductivity of MXenes within MTPs trained from first-principles molecular dynamics simulations in the future.

Universal, minute-scale synthesis of transition metal compound nanocatalysts via graphene-microwave system for enhancing sulfur kinetics in lithium-sulfur batteries.

The application of Li-S batteries on large scale is held back by the sluggish sulfur kinetics and low synthesis efficiency of sulfur host. In addition, the preparation of catalysts that promote polysulfide redox kinetics is complex and time-consuming, reducing the cost of raw materials in Li-S. Here, a universal synthetic strategy for rapid fabrication of sulfur cathode and metal compounds nanocatalysts is reported based on microwave heating of graphene. Heat-sensitive materials can achieve rapid heating due to graphene reaching 500 ℃ within 4 s via microwave irradiation. The MoP-MoS2/rGO catalyst demonstrated in this work was synthesized within 60 s. When used for catalysts for Li-S batteries whose graphene/sulfur cathodes were also synthesized by microwave heating, enhanced catalytic effect for sulfur redox reaction was verified via experimental and DFT theoretical results. Benefiting from fast redox reaction (MoP), smooth Li+ diffusion pathways (MoS2), and large conductive network (rGO), the assembled Li-S battery with MoP-MoS2/rGO-Add@CS displays a remarkable initial specific capacity, stable lithium anode and good cycle stability (in pouch cells) using this two-pronged strategy. The work provides a practical strategy for advanced Li-S batteries toward a wide range of applications.

Postoperative Dipping Patterns of Mean Arterial Pressure and Mortality After Coronary Artery Bypass Grafting.

Blood pressure dipping patterns have long been considered to be associated with adverse events. We aimed to investigate whether dipping patterns of postoperative MAP were related to 90-day and hospital mortality in patients undergoing CABG. Four thousand three hundred ninety-one patients were classified into extreme dippers (night-to-day ratio of MAP ≤ 0.8), dippers (0.8 < night-to-day ratio of MAP ≤ 0.9), non-dippers (0.9 < night-to-day ratio of MAP ≤ 1), and reverse dippers (> 1). Compared with non-dippers, reverse dippers were at a higher risk of 90-day mortality (aHR = 1.58; 95% CI, 1.10-2.27) and hospital mortality (aOR = 1.97; 95% CI, 1.12-3.47). A significant interaction was observed between hypertension and dipping patterns (P for interaction = 0.02), with a significant increased risk of 90-day mortality in non-hypertensive reverse dippers (aHR = 1.90; 95% CI, 1.17-3.07) but not in hypertensive reverse dippers (aHR = 1.26; 95% CI, 0.73-2.19).

Knowledge, Attitude, and Practice Towards Mpox and Associated Factors Among HIV-Infected Individuals - Beijing Municipality, China, 2023.

What is already known about this topic?: Approximately 50% of patients with mpox are human immunodeficiency virus (HIV)-infected globally. Studies have shown that individuals with advanced HIV infection tend to have more severe clinical manifestations and higher mortality rates after mpox infection. What is added by this report?: The study revealed that individuals living with HIV have a low level of Knowledge, Attitude, and Practice (KAP) towards mpox. Several factors, including age, registered residence, sexual orientation, education level, viral load, and co-occurrence of other sexually transmitted diseases, were found to influence the KAP towards mpox. What are the implications for public health practice?: This study is the first to investigate the KAP of mpox among individuals living with HIV. The findings suggest that mpox health education should prioritize individuals with co-existing sexually transmitted diseases (STDs) and a high viral load.

Reconfigurable spin current transmission and magnon-magnon coupling in hybrid ferrimagnetic insulators.

Coherent spin waves possess immense potential in wave-based information computation, storage, and transmission with high fidelity and ultra-low energy consumption. However, despite their seminal importance for magnonic devices, there is a paucity of both structural prototypes and theoretical frameworks that regulate the spin current transmission and magnon hybridization mediated by coherent spin waves. Here, we demonstrate reconfigurable coherent spin current transmission, as well as magnon-magnon coupling, in a hybrid ferrimagnetic heterostructure comprising epitaxial Gd3Fe5O12 and Y3Fe5O12 insulators. By adjusting the compensated moment in Gd3Fe5O12, magnon-magnon coupling was achieved and engineered with pronounced anticrossings between two Kittel modes, accompanied by divergent dissipative coupling approaching the magnetic compensation temperature of Gd3Fe5O12 (TM,GdIG), which were modeled by coherent spin pumping. Remarkably, we further identified, both experimentally and theoretically, a drastic variation in the coherent spin wave-mediated spin current across TM,GdIG, which manifested as a strong dependence on the relative alignment of magnetic moments. Our findings provide significant fundamental insight into the reconfiguration of coherent spin waves and offer a new route towards constructing artificial magnonic architectures.