Search Results (25)

Iridium pyridine diimine (PDI) complexes provide a versatile platform for highly reactive Ir–nitrido species with pronounced multiple-bond character, capable of activating H–H, C–H, Si–H, and even C–C bonds. Building on this chemistry, we extended our studies to a system with a terminal Ir–S bond, starting from our recently reported PDI–Ir–SH complex, which exhibits partial multiple-bond character. Upon addition of the 2,4,6-tri-tert-butylphenoxy radical, the corresponding phenol and a tentative Ir–S• radical intermediate are formed at ambient temperature. DFT and LNO-CCSD(T) calculations consistently reveal a low barrier for this process, with the spin density localized primarily on sulfur, accounting for subsequent S–S coupling reactions. Instead of the anticipated dimeric disulfido Ir–S₂–Ir complex formed along a least-motion pathway, a trisulfido Ir–S₃–Ir species was obtained, and characterized by NMR spectroscopy, X-ray crystallography and mass spectrometry. The formation mechanism of the trisulfido complex was further elucidated by DFT calculations. Remarkably, the sulfur-bridge formation is thermally reversible, regenerating the monomeric sulfanido Ir–SH complex. The origin of the hydrogen atom was investigated using H₂, D₂, and deuterated solvents. Full article

WS₂ is a promising material for applications in wearable devices, field-effect transistors, and high-performance heterojunctions. However, significant challenges remain regarding effective regulation and temperature stability. This study investigates the temperature-dependent electrical properties of WS₂ heterojunctions prepared by electrophoretic deposition on boron-doped diamond films. The results reveal that the rectification ratio of lightly doped boron heterojunctions at room temperature is 9.1, indicating thermal excitation behavior at temperatures above 100 °C. In contrast, heavily doped boron heterojunctions maintain a rectification ratio consistently below 1 over a temperature range from room temperature to 180 °C, indicating reverse rectification. The lowest rectification ratio observed at 140 °C is 0.17. Density functional theory (DFT) calculations suggest that hydrogen (H) termination generates an internal electric field in the opposite direction, causing a reversal of the rectification polarity, while oxygen (O) termination favors forward rectification. Additionally, due to vacancy defects in WS₂, the heterojunction exhibits negative differential resistance at 120 °C, with a peak-to-valley ratio of 2.4. Higher doping levels, in comparison to lower concentrations, offer a more stable rectification ratio at elevated temperatures, making the material more suitable for high-temperature, high-frequency, and high-power applications. Full article

MXenes, a rapidly emerging family of two-dimensional transition metal carbides and nitrides, have attracted considerable attention in recent years for their potential in next-generation energy storage technologies. In solid-state batteries (SSBs), they combine metallic-level conductivity (>10³ S cm⁻¹), adjustable surface terminations, and mechanical resilience, which makes them suitable for diverse functions within the cell architecture. Current studies have shown that MXene-based anodes can deliver reversible lithium storage with Coulombic efficiencies approaching ~98% over 500 cycles, while their use as conductive additives in cathodes significantly improves electron transport and rate capability. As interfacial layers or structural scaffolds, MXenes effectively buffer volume fluctuations and suppress lithium dendrite growth, contributing to extended cycle life. In solid polymer and composite electrolytes, MXene fillers have been reported to increase Li⁺ conductivity to the 10⁻³–10⁻² S cm⁻¹ range and enhance Li⁺ transference numbers (up to ~0.76), thereby improving both ionic transport and mechanical stability. Beyond established Ti-based systems, double transition metal MXenes (e.g., Mo₂TiC₂, Mo₂Ti₂C₃) and hybrid heterostructures offer expanded opportunities for tailoring interfacial chemistry and optimizing energy density. Despite these advances, large-scale deployment remains constrained by high synthesis costs (often exceeding USD 200–400 kg⁻¹ for Ti₃C₂T_x at lab scale), restacking effects, and stability concerns, highlighting the need for greener etching processes, robust quality control, and integration with existing gigafactory production lines. Addressing these challenges will be crucial for enabling MXene-based SSBs to transition from laboratory prototypes to commercially viable, safe, and high-performance energy storage systems. Beyond summarizing performance, this review elucidates the mechanistic roles of MXenes in SSBs—linking lithiophilicity, field homogenization, and interphase formation to dendrite suppression at Li|SSE interfaces, and termination-assisted salt dissociation, segmental-motion facilitation, and MWS polarization to enhanced electrolyte conductivity—thereby providing a clear design rationale for practical implementation. Full article

As a promising polymer for the production of biomaterials and drug delivery systems, poly(lactic acid) (PLA) is characterized by its relative hydrophobicity, as well as its chemical and biological inertness. Here, we aimed to improve the biological properties of PLA-based materials via the covalent attachment of a hydrophilic biocompatible glycopolymer, namely poly(2-deoxy-N-methacrylamido-D-glucose) (PMAG) on their surface. PMAG is a water-soluble polymer that contains glucose units in its side chains, which are responsible for good biocompatibility and the ability to attach bioactive molecules. In the developed protocol, PMAG was synthesized by controlled radical polymerization in the presence of a reversible addition–fragmentation chain transfer (RAFT) agent, followed by the conversion of glycopolymer terminal dithiobenzoate functionality into a primary amino group (PMAG-NH₂). PLA-based films served as model aliphatic polyester materials for developing the surface biofunctionalization protocol. According to that, PMAG-NH₂ covalent immobilization was carried out after alkali treatment, allowing the generation of the surface-located carboxyl groups and their activation. The developed modification method provided a one-point attachment of hydrophilic PMAG to the hydrophobic PLA surface. PMAG samples, which differed by the degree of polymerization, and the variation of polymer concentration in the reaction medium were applied to investigate the modification efficacy and grafting density. The developed single-point polymer grafting approach provided the efficient functionalization with a grafting density in the range of 5–23 nmol/cm². The neat and modified polymer films were characterized by a number of methods, namely atomic force microscopy, thermogravimetric analysis, ellipsometry, and contact angle measurements. In addition, an ArgGlyAsp-containing peptide (RGD peptide) was conjugated to the PMAG macromolecules grafted on the surface of PLA films. It was shown that both surface modification with PMAG and with PMAG-RGD peptide enhanced the adhesion and growth of mesenchymal stem cells as compared to a neat PLA surface. Full article

Dynamic wireless power transfer (DWPT) systems with segmented transmitters suffer from output pulsations during the moving process. Although numerous coil structures have been developed to mitigate this fluctuation, the parameter design process is complicated and restricted by specific working conditions (e.g., air gaps). To solve these problems, a novel reverse-bent modular transmitter structure is proposed for DWPT in industrial automatic application scenarios such as linear transport systems. Considering the heterogeneous current density distribution in the adjacent region between two coils which causes a drop in magnetic field, the proposed coil structure attempts to eliminate the effects of the adjacent region by bending the terminal parts of each coil reversely to the ferrite layer for shielding. Compared to traditional planar couplers, this structure array can generate a uniform magnetic field over various air gaps. A 100 W laboratory prototype was built to verify the feasibility of the proposed system. The experimental results show that the proposed system achieved a constant output voltage, and the output pulsation was within ±2.3% in the dynamic powering process. The average efficiency was about 88.29%, with a 200 mm transfer distance. When the air gap varied from 20 mm to 30 mm, the system could still retain constant voltage output characteristics. Full article

Density reversal of senescent red blood cells has been known for a long time, yet the identity of the candidate ion transporter(s) causing the senescent cells to swell is still elusive. While performing fractionation of RBCs from healthy individuals in Percoll density gradient and characterization of the separated fractions, we identified a subpopulation of cells in low-density fraction (1.02% ± 0.47) showing signs of senescence such as loss of membrane surface area associated with a reduction in band 3 protein abundance, and Phosphatidylserine (PS) exposure to the outer membrane. In addition, we found that these cells are overloaded with Na⁺ and Ca²⁺. Using a combination of blockers and activators of ion pumps and channels, we revealed reduced activity of Plasma membrane Ca²⁺ ATPase and an increase in Ca²⁺ and Na⁺ leaks through ion channels in senescent-like cells. Our data revealed that Ca²⁺ overload in these cells is a result of reduced PMCA activity and facilitated Ca²⁺ uptake via a hyperactive Piezo1 channel. However, we could not exclude the contribution of other Ca²⁺-permeable ion channels in this scenario. In addition, we found, as a universal mechanism, that an increase in intracellular Ca²⁺ reduced the initially high selectivity of Piezo1 channel for Ca²⁺ and allowed higher Na⁺ uptake, Na⁺ accumulation, and swelling. Full article

In this work, by employing field plate (FP) and N ion-implantation edge termination (NIET) structure, the electrical performance of the β-Ga₂O₃ Schottky barrier diode (SBD) was greatly improved. Ten samples of vertical SBDs were fabricated to investigate the influence of the relative positions of field plates (FPs) and ion implantation on the device performance. The device with the FP of 15 μm and the ion implantation at the edge of the Schottky electrode exhibited a breakdown voltage (V_br) of 1616 V, a specific on-resistance (R_on,sp) of 5.11 mΩ·cm², a power figure of merit (PFOM) of 0.511 GW/cm², and a reverse current density of 1.2 × 10⁻⁵ A/cm² @ −1000 V. Compared to the control device, although the R_on,sp increased by 1 mΩ·cm², the V_br of the device increased by 183% and the PFOM increased by 546.8%. Moreover, the reverse leakage current of the device with the FP and NIET structure decreased by three orders of magnitude. The TCAD simulation revealed that the peak electric field at the interface decreased from 7 MV/cm @ −500 V to 4.18 MV/cm @ −1000 V. These results demonstrate the great potential for the β-Ga₂O₃ SBD with a FP and NIET structure in power electronic applications. Full article

Ca²⁺ binding to the ubiquitous Ca²⁺ sensing protein calmodulin (CaM) activates the intermediate conductance Ca²⁺-activated SK4 channel. Potential hydrophilic pockets for CaM binding have been identified at the intracellular HA and HB helices in the C-terminal of SK4 from the three published cryo-EM structures of SK4. Single charge reversal substitutions at either site, significantly weakened the pull-down of SK4 by CaM wild-type (CaM), and decreased the TRAM-34 sensitive outward K⁺ current densities in native HEK293T cells when compared with SK4 WT measured under the same conditions. Only the doubly substituted SK4 R352D/R355D (HB helix) obliterated the CaM-mediated pull-down and thwarted outward K⁺ currents. However, overexpression of CaM E84K/E87K, which had been predicted to face the arginine doublet, restored the CaM-mediated pull-down of SK4 R352D/R355D and normalized its whole-cell current density. Virtual analysis of the putative salt bridges supports a unique role for the positively charged arginine doublet at the HB helix into anchoring the interaction with the negatively charged CaM glutamate 84 and 87 CaM. Our findings underscore the unique contribution of electrostatic interactions in carrying CaM binding onto SK4 and support the role of the C-terminal HB helix to the Ca²⁺-dependent gating process. Full article

Clinical and preclinical studies indicate that adaptations in corticostriatal neurotransmission significantly contribute to heroin relapse vulnerability. In animal models, heroin self-administration and extinction produce cellular adaptations in both neurons and astrocytes within the nucleus accumbens (NA) core that are required for cue-induced heroin seeking. Specifically, decreased glutamate clearance and reduced association of perisynaptic astrocytic processes with NAcore synapses allow glutamate release from prelimbic (PrL) cortical terminals to engage synaptic and structural plasticity in NAcore medium spiny neurons. Normalizing astrocyte glutamate homeostasis with drugs like the antioxidant N-acetylcysteine (NAC) prevents cue-induced heroin seeking. Surprisingly, little is known about heroin-induced alterations in astrocytes or pyramidal neurons projecting to the NAcore in the PrL cortex (PrL-NAcore). Here, we observe functional adaptations in the PrL cortical astrocyte following heroin self-administration (SA) and extinction as measured by the electrophysiologically evoked plasmalemmal glutamate transporter 1 (GLT-1)-dependent current. We likewise observed the increased complexity of the glial fibrillary acidic protein (GFAP) cytoskeletal arbor and increased association of the astrocytic plasma membrane with synaptic markers following heroin SA and extinction training in the PrL cortex. Repeated treatment with NAC during extinction reversed both the enhanced astrocytic complexity and synaptic association. In PrL-NAcore neurons, heroin SA and extinction decreased the apical tuft dendritic spine density and enlarged dendritic spine head diameter in male Sprague–Dawley rats. Repeated NAC treatment during extinction prevented decreases in spine density but not dendritic spine head expansion. Moreover, heroin SA and extinction increased the co-registry of the GluA1 subunit of AMPA receptors in both the dendrite shaft and spine heads of PrL-NAcore neurons. Interestingly, the accumulation of GluA1 immunoreactivity in spine heads was further potentiated by NAC treatment during extinction. Finally, we show that the NAC treatment and elimination of thrombospondin 2 (TSP-2) block cue-induced heroin relapse. Taken together, our data reveal circuit-level adaptations in cortical dendritic spine morphology potentially linked to heroin-induced alterations in astrocyte complexity and association at the synapses. Additionally, these data demonstrate that NAC reverses PrL cortical heroin SA-and-extinction-induced adaptations in both astrocytes and corticostriatal neurons. Full article

Hair thinning is a very common problem in dermatology, affecting both men and women, and can strongly impact the quality of life of subjects. In this view, therapies that aim to reduce the appearance of thinning by delaying, arresting, or reversing the course of hair thinning are highly desirable. A novel nutraceutical product (NS) containing active botanicals, a patented composition comprising rutin and polyunsaturated fatty acids (PUFAs), zinc, biotin, and ornithine, has been developed to improve hair growth in subjects with hair thinning. Sixty subjects with telogen effluvium-like hair loss were randomized 1:1 in two groups (NS vs. placebo) and treated for three months and evaluated at the baseline visit (T0), and after 15 days (T1) and one (T2), two (T3), and three (T4) months of treatment. Two follow-up visits one month (T5) and two months after the last assumption (T6) were also included in the protocol. Subjects were evaluated for the percentage of hair in the anagen phase, density of hair in the anagen phase (n/cm²), vellus hair (miniaturized, smaller, and thinner hair), and the entity of hair loss in the telogen phase (pull test). NS supplementation produced a statistically significant (p < 0.05) increase in anagen hair and hair density versus baseline from 15 days (T1) of treatment and this effect was not detectable for placebo. Moreover, a clinically/statistically significant (p < 0.05) decrease in vellus hair was also reported, suggesting not only a rapid reduction of the process of miniaturization of the hair but also a transformation of vellus hair into terminal hair. The NS treatment also showed a significant (p < 0.05) increase in tensile strength till T6 (vs. placebo). A higher percentage of subjects who took the NS noted a reduction in daily hair loss, an increase in brightness, and the presence of stronger hair. No side effects were reported. The present study confirms the clinical efficacy and safety of novel nutraceutical supplements in men and women with hair thinning, acting as a multi-targeted therapeutic approach to hair thinning due to TE-like phenomena. Full article

Two-dimensional transition metal carbides/carbonitrides (MXenes) have broad application prospects in the field of energy storage due to their abundant surface functional groups, tunable interlayer spacing, and excellent electrical conductivity. However, the kinetics of Li-ion intercalation/deintercalation between MXene layers is slow, and the stacking between nanosheets due to long cycling reduces the structural stability and battery safety. Herein, we prepare and tune surface-termination groups of Ti₃C₂T_x MXene by chemical exfoliation and low-temperature annealing methods. The types of functional groups on the surface of the material are optimized by the substitution of oxygen to some -F functional groups on the surface. The optimized Ti₃C₂T_x MXene material exhibits a reversible lithium-ion-storage specific capacity of 444.1 mAh g⁻¹ after 200 cycles at a current density of 0.1 A g⁻¹. The increased of -O functional groups can increase the diffusion rate of Li⁺, promote the transport of electrons, and accelerate the kinetics of the electrode reaction, thereby improving the performance of lithium-ion storage. Full article

Diarylethene is a prototypical molecular switch that can be reversibly photoisomerized between its open and closed forms. Ligands bpy-DAE-bpy, consisting of a phenyl-diarylethene-phenyl (DAE) central core and bipyridine (bpy) terminal substituents, are able to self-organize. They are investigated by scanning tunneling microscopy at the solid–liquid interface. Upon light irradiation, cooperative photochromic switching of the ligands is recognized down to the submolecular level. The closed isomers show different electron density of states (DOS) contrasts, attributed to the HOMO or LUMO molecular orbitals observed. More importantly, the LUMO images show remarkable differences between the open and closed isomers, attributed to combined topographic and electronic contrasts mainly on the DAE moieties. The electronic contrasts from multiple HOMO or LUMO distributions, combined with topographic distortion of the open or closed DAE, are interpreted by density functional theory (DFT) calculations. Full article

In this work, the potentials of two-dimensional Ti₂N and its derivative nanosheets Ti₂NT₂(T=O, F, OH) for some harmful nitrogen-containing gas (NCG) adsorption and sensing applications have been unveiled based on the quantum-mechanical Density Functional Theory calculations. It is found that the interactions between pure Ti₂N and NCGs (including NO, NO₂, and NH₃ in this study) are very strong, in which NO and NO₂ can even be dissociated, and this would poison the substrate of Ti₂N monolayer and affect the stability of the sensing material. For the monolayer of Ti₂NT₂(T=O, F, OH) that is terminated by functional groups on surface, the adsorption energies of NCGs are greatly reduced, and a large amount of charges are transferred to the functional group, which is beneficial to the reversibility of the sensing material. The significant changes in work function imply the good sensitivity of the above mentioned materials. In addition, the fast response time further consolidates the prospect of two-dimensional Ti₂NT₂ as efficient NCGs’ sensing materials. This theoretical study would supply physical insight into the NCGs’ sensing mechanism of Ti₂N based nanosheets and help experimentalists to design better 2-D materials for gas adsorption or sensing applications. Full article

We have explored the impact of elevated growth and annealing temperatures on the local interfacial structure of thin Fe(12 nm)/Pt(10 nm) spintronic bilayers, epitaxially grown on MgO (100), and their correlation to magnetization reversal and dynamics. Electron-beam evaporation growth and subsequent annealing at 450 °C causes significant roughening of the MgO/Fe interface with irregular steps and multilevel (100) MgO surface terraces. Consequently, threading dislocations emerging at the step edges propagated in the Fe layer and terminated at the Fe/Pt interface, which appears pitted with pits 1.5–3 nm deep on the Fe side. Most of the pits are filled with the overlying Pt, whereby others by ferrimagnetic Fe₃O₄, forming nanoparticles that occupy nearly 9% of the Fe/Pt interfacial area. Fe₃O₄ nanoparticles occur at the termination sites of threading dislocations at the Fe/Pt interface, and their population density is equivalent to the density of threading dislocations in the Fe layer. The morphology of the Fe/Fe₃O₄/Pt system has a strong impact on the magnetization reversal, enhancing the coercive field and inducing an exchange bias below 200 K. Furthermore, low-temperature spin pumping and inverse spin Hall effect voltage measurements reveal that below their blocking temperature the nanoparticles can influence the spin current transmission and the spin rectification effects. Full article

Neurogenesis and functional brain activity require complex associations of inherently programmed secretory elements that are regulated precisely and temporally. Family with sequence similarity 19 A1 (FAM19A1) is a secreted protein primarily expressed in subsets of terminally differentiated neuronal precursor cells and fully mature neurons in specific brain substructures. Several recent studies have demonstrated the importance of FAM19A1 in brain physiology; however, additional information is needed to support its role in neuronal maturation and function. In this study, dendritic spine morphology in Fam19a1-ablated mice and neurite development during in vitro neurogenesis were examined to understand the putative role of FAM19A1 in neural integrity. Adult Fam19a1-deficient mice showed low dendritic spine density and maturity with reduced dendrite complexity compared to wild-type (WT) littermates. To further explore the effect of FAM19A1 on neuronal maturation, the neurite outgrowth pattern in primary neurons was analyzed in vitro with and without FAM19A1. In response to FAM19A1, WT primary neurons showed reduced neurite complexity, whereas Fam19a1-decifient primary neurons exhibited increased neurite arborization, which was reversed by supplementation with recombinant FAM19A1. Together, these findings suggest that FAM19A1 participates in dendritic spine development and neurite arborization. Full article