GPS-SUMO 2.0: an updated online service for the prediction of SUMOylation sites and SUMO-interacting motifs.

Small ubiquitin-like modifiers (SUMOs) are tiny but important protein regulators involved in orchestrating a broad spectrum of biological processes, either by covalently modifying protein substrates or by noncovalently interacting with other proteins. Here, we report an updated server, GPS-SUMO 2.0, for the prediction of SUMOylation sites and SUMO-interacting motifs (SIMs). For predictor training, we adopted three machine learning algorithms, penalized logistic regression (PLR), a deep neural network (DNN), and a transformer, and used 52 404 nonredundant SUMOylation sites in 8262 proteins and 163 SIMs in 102 proteins. To further increase the accuracy of predicting SUMOylation sites, a pretraining model was first constructed using 145 545 protein lysine modification sites, followed by transfer learning to fine-tune the model. GPS-SUMO 2.0 exhibited greater accuracy in predicting SUMOylation sites than did other existing tools. For users, one or multiple protein sequences or identifiers can be input, and the prediction results are shown in a tabular list. In addition to the basic statistics, we integrated knowledge from 35 public resources to annotate SUMOylation sites or SIMs. The GPS-SUMO 2.0 server is freely available at https://sumo.biocuckoo.cn/. We believe that GPS-SUMO 2.0 can serve as a useful tool for further analysis of SUMOylation and SUMO interactions.

Optically Tunable Electrical Oscillations in Oxide-Based Memristors for Neuromorphic Computing.

The application of hardware-based neural networks can be enhanced by integrating sensory neurons and synapses that enable direct input from external stimuli. This work reports direct optical control of an oscillatory neuron based on volatile threshold switching in V3O5. The devices exhibit electroforming-free operation with switching parameters that can be tuned by optical illumination. Using temperature-dependent electrical measurements, conductive atomic force microscopy (C-AFM), in situ thermal imaging, and lumped element modelling, it is shown that the changes in switching parameters, including threshold and hold voltages, arise from overall conductivity increase of the oxide film due to the contribution of both photoconductive and bolometric characteristics of V3O5, which eventually affects the oscillation dynamics. Furthermore, V3O5 is identified as a new bolometric material with a temperature coefficient of resistance (TCR) as high as -4.6% K-1 at 423 K. The utility of these devices is illustrated by demonstrating in-sensor reservoir computing with reduced computational effort and an optical encoding layer for spiking neural network (SNN), respectively, using a simulated array of devices.

Comparing the osteogenesis outcomes of different lumbar interbody fusions (A/O/X/T/PLIF) by evaluating their mechano-driven fusion processes.

BACKGROUND: In lumbar interbody fusion (LIF), achieving proper fusion status requires osteogenesis to occur in the disc space. Current LIF techniques, including anterior, oblique, lateral, transforaminal, and posterior LIF (A/O/X/T/PLIF), may result in varying osteogenesis outcomes due to differences in biomechanical characteristics. METHODS: A mechano-regulation algorithm was developed to predict the fusion processes of A/O/X/T/PLIF based on finite element modeling and iterative evaluations of the mechanobiological activities of mesenchymal stem cells (MSCs) and their differentiated cells (osteoblasts, chondrocytes, and fibroblasts). Fusion occurred in the grafting region, and each differentiated cell type generated the corresponding tissue proportional to its concentration. The corresponding osteogenesis volume was calculated by multiplying the osteoblast concentration by the grafting volume. RESULTS: TLIF and ALIF achieved markedly greater osteogenesis volumes than did PLIF and O/XLIF (5.46, 5.12, 4.26, and 3.15 cm3, respectively). Grafting volume and cage size were the main factors influencing the osteogenesis outcome in patients treated with LIF. A large grafting volume allowed more osteoblasts (bone tissues) to be accommodated in the disc space. A small cage size reduced the cage/endplate ratio and therefore decreased the stiffness of the LIF. This led to a larger osteogenesis region to promote osteoblastic differentiation of MSCs and osteoblast proliferation (bone regeneration), which subsequently increased the bone fraction in the grafting space. CONCLUSION: TLIF and ALIF produced more favorable biomechanical environments for osteogenesis than did PLIF and O/XLIF. A small cage and a large grafting volume improve osteogenesis by facilitating osteogenesis-related cell activities driven by mechanical forces.

Bulk Schottky Junctions-Based Flexible Triboelectric Nanogenerators to Power Backscatter Communications in Green 6G Networks.

This work introduces a novel method to construct Schottky junctions to boost the output performance of triboelectric nanogenerators (TENGs). Perovskite barium zirconium titanate (BZT) core/metal silver shell nanoparticles are synthesized to be embedded into electrospun polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) nanofibers before they are used as tribo-negative layers. The output power of TENGs with composite fiber mat exhibited >600% increase compared to that with neat polymer fiber mat. The best TENG achieved 1339 V in open-circuit voltage, 40 µA in short-circuit current and 47.9 W m-2 in power density. The Schottky junctions increased charge carrier density in tribo-layers, ensuring a high charge transfer rate while keeping the content of conductive fillers low, thus avoiding charge loss and improving performance. These TENGs are utilized to power radio frequency identification (RFID) tags for backscatter communication (BackCom) systems, enabling ultra-massive connectivity in the 6G wireless networks and reducing information communications technology systems' carbon footprint. Specifically, TENGs are used to provide an additional energy source to the passive tags. Results show that TENGs can boost power for BackCom and increase the communication range by 386%. This timely contribution offers a novel route for sustainable 6G applications by exploiting the expanded communication range of BackCom tags.

Lattice Distortion and Low-Frequency Anharmonic Phonons Suppress Charge Recombination in Lead Halide Perovskites upon Pseudohalide Doping: Time-Domain Ab Initio Analysis.

Perovskite solar cells have witnessed a surge in interest as a promising technology for low-cost, high-efficiency photovoltaics with certified power conversion efficiencies beyond 25%. However, their commercial development is hindered by poor stability and nonradiative losses that restrict their approach to the theoretical efficiency limit. Using ab initio nonadiabatic molecular dynamics, we demonstrate that nonradiative charge recombination is suppressed when the iodide in formamidinium lead iodide (FAPbI3) is partially replaced with pseudohalide anions (SCN-, BF4-, and PF6-). The replacement breaks the symmetry of the system and creates local structural distortion and dynamic disorder, decreasing electron-hole overlap and nonadiabatic electron-vibrational coupling. The charge carrier lifetime is found to increase with increased structural distortion and is the longest for PF6-. This work is fundamentally relevant to the design of high-performance perovskite materials for optoelectronic applications.

Polarization Alignment in Polycrystalline BiFeO3 Photoelectrodes for Tunable Band Bending.

Polarization in a semiconductor can modulate the band bending via the depolarization electric field (EdP), subsequently tuning the charge separation and transfer (CST) process in photoelectrodes. However, the random orientation of dipole moments in many polycrystalline semiconductor photoelectrodes leads to negligible polarization effect. How to effectively align the dipole moments in polycrystalline photoelectrodes into the same direction to maximize the polarization is still to be developed. Herein, we report that the dipole moments in a ferroelectric BiFeO3 photoelectrode can be controlled under external poling, resulting in a tunable CST efficiency. A negative bias of -40 voltage (V) poling to the photoelectrode leads to an over 110% increase of the CST efficiency, while poling at +40 V, the CST efficiency is reduced to only 41% of the original value. Furthermore, a nearly linear relationship between the external poling voltage and surface potential is discovered. The findings here provide an effective method in tuning the band bending and charge transfer of the emerging ferroelectricity driven solar energy conversion.

"Fill the World with Love": Songs with Prosocial Lyrics Enhance Online Charitable Donations among Chinese Adults.

Research has shown that songs with prosocial lyrics can enhance individual prosociality. Building on the general learning model (GLM), this study demonstrated, through real-world charitable organizations, how songs with prosocial lyrics influence helping behavior that uses time as a currency. In Study 1, participants were randomly assigned to conditions of prosocial songs, prosocial lyrics, or neutral songs, and they were instructed to complete an online charity task. The results indicated that compared to the neutral songs, participants listening to prosocial songs and lyrics spent more time donating rice to the United Nations World Food Programme. This effect was replicated in Study 2, employing different media exposure from Study 1 (i.e., listening to background music). Furthermore, investigations into the underlying mechanisms revealed that this effect was mediated by interpersonal empathy. In summary, current findings suggest that songs with prosocial lyrics increase interpersonal empathy, subsequently influencing people's online charitable donation behaviors in daily life.

The effect of brief digital mindfulness-based interventions on increasing online charitable behavior in Chinese adolescents.

Digital mindfulness-based interventions (d-MBIs) have garnered significant research interest in recent years due to their psychological benefits. However, little is known about their impact on prosocial behaviors. This study investigates how d-MBIs impact prosocial behaviors where time spent is money, with Chinese adolescents as the subjects, through an online charity task (www.freerice.com). 119 students from a high school in China, who were inexperienced with mindfulness meditation, participated in this randomized controlled trial. The d-MBI group (N = 39) received online MBI guidance, while the face-to-face mindfulness-based intervention (f-MBI, N = 43) group underwent mindfulness intervention under personal tutors. The active control group (N = 37) completed a crossword task. Data analysis first involved repeated measures variance analysis, including pre-and post-intervention assessments. Subsequently, a two-way variance analysis was performed, with gender (female and male) and group (d-MBI, f-MBI, active control) as independent variables and the number of grains as dependent variables for the three groups of participants. Results showed that d-MBIs effectively improved empathy and compassion in Chinese adolescents, leading to increased rice donations to the United Nations World Food Program. These results underscore the positive effect of d-MBIs on prosociality and suggest their applicability in beneficial real-world situations involving prosocial behaviors, extending beyond previous research primarily conducted in artificial and hypothetical scenarios.

Pancreatic lipase-related protein 2 is selectively expressed by peritubular myoid cells in the murine testis and sustains long-term spermatogenesis.

Spermatogenesis is a complicated process of germ cell differentiation that occurs within the seminiferous tubule in the testis. Peritubular myoid cells (PTMCs) produce major components of the basement membrane that separates and ensures the structural integrity of seminiferous tubules. These cells secrete niche factors to promote spermatogonial stem cell (SSC) maintenance and mediate androgen signals to direct spermatid development. However, the regulatory mechanisms underlying the identity and function of PTMCs have not been fully elucidated. In the present study, we showed that the expression of pancreatic lipase-related protein 2 (Pnliprp2) was restricted in PTMCs in the testis and that its genetic ablation caused age-dependent defects in spermatogenesis. The fertility of Pnliprp2 knockout animals (Pnliprp2-/-) was normal at a young age but declined sharply beginning at 9 months. Pnliprp2 deletion impaired the homeostasis of undifferentiated spermatogonia and severely disrupted the development and function of spermatids. Integrated analyses of single-cell RNA-seq and metabolomics data revealed that glyceride metabolism was changed in PTMCs from Pnliprp2-/- mice. Further analysis found that 60 metabolites were altered in the sperm of the Pnliprp2-/- animals; notably, lipid metabolism was significantly dysregulated. Collectively, these results revealed that Pnliprp2 was exclusively expressed in PTMCs in the testis and played a novel role in supporting continual spermatogenesis in mice. The outcomes of these findings highlight the function of lipid metabolism in reproduction and provide new insights into the regulation of PTMCs in mammals.

Time Matters: Time Perspectives Predict Intertemporal Prosocial Preferences.

The study utilizes the Chinese version of the Zimbardo Time Perspective Inventory (ZTPI-C) and a novelty intertemporal prosocial discounting paradigm to explore the preferences of individuals with the Present Impulsive Time Perspective (PITP) and the Future Time Perspective (FTP) in intertemporal prosocial choices, and uncovers the cognitive mechanisms underpinning intertemporal altruism from the personality traits. The findings revealed: (1) The donation behaviors of both groups decreased as time delay rose, aligning with the hyperbolic model. (2) PITP individuals had significantly higher discount rates than those with FTP, and the scores of FTP individuals on the "Future" dimension of the ZTPI-C were positively correlated with the amount of money they were willing to forgo. These results suggest that time perspective, as a stable personality trait, can predict individuals' intertemporal prosocial preferences. Our research enriches the theory of intertemporal choices and extends the Perceived-time-based model (PTBM) to the domain of intertemporal social preferences.

Two anthracene-based zirconium metal-organic frameworks with fcu and hcp topologies as versatile fluorescent sensors for detection of inorganic ions and nitroaromatics.

Two anthracene-based zirconium metal-organic frameworks (UiO-68-AN-fcu and UiO-68-AN-hcp) with blue emission were synthesized by the solvothermal reaction of ZrCl4 with anthracene-based ligand 4,4'-(9,10-anthracenediyl)dibenzoic acid. The two MOFs inherited the luminescence properties of anthracene-based ligand and exhibited different topologies due to the change of connection mode of Zr-O clusters. The two stable anthracene-based zirconium MOFs served as luminescent sensors for selectively detecting 2-nitrophenol, Fe3+ and Cr2O72-. UiO-68-AN-hcp with flower morphology exhibited stronger quenching effect for 2-nitrophenol, Fe3+ and Cr2O72- by comparing to UiO-68-AN-fcu. Adsorption tests, fluorescence lifetime and spectroscopy studies demonstrated that the fluorescence responses of MOFs for analytes can be primarily attributed to the dynamic quenching mechanism involving energy and electron transfer. These results revealed that the combination of luminescent anthracene-based ligand and Zr-O clusters is a feasible strategy to construst MOFs-based fluorescent sensors.

Biomechanical properties of different anterior and posterior techniques for atlantoaxial fixation: a finite element analysis.

BACKGROUND: Many techniques for atlantoaxial fixation have been developed. However, the biomechanical differences among various atlantoaxial fixation methods remain unclear. This study aimed to evaluate the biomechanical influence of anterior and posterior atlantoaxial fixation techniques on fixed and nonfixed segments. METHODS: An occiput-C7 cervical finite element model was used to construct 6 surgical models including a Harms plate, a transoral atlantoaxial reduction plate (TARP), an anterior transarticular screw (ATS), a Magerl screw, a posterior screw-plate, and a screw-rod system. Range of motion (ROM), facet joint force (FJF), disc stress, screw stress, and bone-screw interface stress were calculated. RESULTS: The C1/2 ROMs were relatively small in the ATS and Magerl screw models under all loading directions except for extension (0.1°-1.0°). The posterior screw-plate system and screw-rod system generated greater stresses on the screws (77.6-1018.1 MPa) and bone-screw interfaces (58.3-499.0 MPa). The Harms plate and TARP models had relatively small ROMs (3.2°-17.6°), disc stress (1.3-7.6 MPa), and FJF (3.3-106.8 N) at the nonfixed segments. Changes in disc stress and FJF of the cervical segments were not consistent with changes in ROM. CONCLUSIONS: ATS and Magerl screws may provide good atlantoaxial stability. The posterior screw-rod system and screw-plate system may have higher risks of screw loosening and breakage. The Harms plate and TARP model may more effectively relieve nonfixed segment degeneration than other techniques. The C0/1 or C2/3 segment may not be more susceptible to degeneration than other nonfixed segments after C1/2 fixation.

IrOx·nH2O with lattice water-assisted oxygen exchange for high-performance proton exchange membrane water electrolyzers.

The trade-off between activity and stability of oxygen evolution reaction (OER) catalysts in proton exchange membrane water electrolyzer (PEMWE) is challenging. Crystalline IrO2 displays good stability but exhibits poor activity; amorphous IrOx exhibits outstanding activity while sacrificing stability. Here, we combine the advantages of these two materials via a lattice water-incorporated iridium oxide (IrOx·nH2O) that has short-range ordered structure of hollandite-like framework. We confirm that IrOx·nH2O exhibits boosted activity and ultrahigh stability of >5700 hours (~8 months) with a record-high stability number of 1.9 × 107 noxygen nIr-1. We evidence that lattice water is active oxygen species in sustainable and rapid oxygen exchange. The lattice water-assisted modified OER mechanism contributes to improved activity and concurrent stability with no apparent structural degradation, which is different to the conventional adsorbate evolution mechanism and lattice oxygen mechanism. We demonstrate that a high-performance PEMWE with IrOx·nH2O as anode electrocatalyst delivers a cell voltage of 1.77 V at 1 A cm-2 for 600 hours (60°C).

Machine Learning-Enabled Superior Energy Storage in Ferroelectric Films with a Slush-Like Polar State.

Heterogeneities in structure and polarization have been employed to enhance the energy storage properties of ferroelectric films. The presence of nonpolar phases, however, weakens the net polarization. Here, we achieve a slush-like polar state with fine domains of different ferroelectric polar phases by narrowing the large combinatorial space of likely candidates using machine learning methods. The formation of the slush-like polar state at the nanoscale in cation-doped BaTiO3 films is simulated by phase field simulation and confirmed by aberration-corrected scanning transmission electron microscopy. The large polarization and the delayed polarization saturation lead to greatly enhanced energy density of 80 J/cm3 and transfer efficiency of 85% over a wide temperature range. Such a data-driven design recipe for a slush-like polar state is generally applicable to quickly optimize functionalities of ferroelectric materials.

A swelling-based biphasic analysis on the quasi-static biomechanical behaviors of healthy and degenerative intervertebral discs.

BACKGROUND AND OBJECTIVE: The degeneration of intervertebral discs is significantly dependent of the changes in tissue composition ratio and tissue structure. Up to the present, the effects of degeneration on the quasi-static biomechanical responses of discs have not been well understood. The goal of this study is to quantitatively analyze the quasi-static responses of healthy and degenerative discs. METHODS: Four biphasic swelling-based finite element models are developed and quantitatively validated. Four quasi-static test protocols, including the free-swelling, slow-ramp, creep and stress-relaxation, are implemented. The double Voigt and double Maxwell models are further used to extract the immediate (or residual), short-term and long-term responses of these tests. RESULTS: Simulation results show that both the swelling-induced pressure in the nucleus pulposus and the initial modulus decrease with degeneration. In the free-swelling test of discs possessing healthy cartilage endplates, simulation results show that over 80% of the total strain is contributed by the short-term response. The long-term response is dominant for discs with degenerated permeability in cartilage endplates. For the creep test, over 50% of the deformation is contributed by the long-term response. In the stress-relaxation test, the long-term stress contribution occupies approximately 31% of total response and is independent of degeneration. Both the residual and short-term responses vary monotonically with degeneration. In addition, both the glycosaminoglycan content and permeability affect the engineering equilibrium time constants of the rheologic models, in which the determining factor is the permeability. CONCLUSIONS: The content of glycosaminoglycan in intervertebral soft tissues and the permeability of cartilage endplates are two critical factors that affect the fluid-dependent viscoelastic responses of intervertebral discs. The component proportions of the fluid-dependent viscoelastic responses depend also strongly on test protocols. In the slow-ramp test, the glycosaminoglycan content is responsible for the changes of the initial modulus. Since existing computational models simulate disc degenerations only by altering disc height, boundary conditions and material stiffness, the current work highlights the significance of biochemical composition and cartilage endplates permeability in the biomechanical behaviors of degenerated discs.

Roles of irregularity of pore morphology in osteogenesis of Voronoi scaffolds: From the perspectives of MSC adhesion and mechano-regulated osteoblast differentiation.

Bone scaffolds designed based on the Voronoi-tessellation algorithm have been increasingly studied owing to their structural similarity with natural cancellous bone. The irregularity of pore morphology (IPM) influences the osteogenesis efficiency of Voronoi scaffolds since it may alter the static and hydromechanical microenvironments for the initial adhesion and mechano-regulated osteoblast differentiation (MrOD) of mesenchymal stem cells (MSCs). In this work, animal experiments were conducted to explore the relationship between IPM and osteogenesis efficiency in Voronoi scaffolds. A computational fluid dynamics (CFD) analysis based on discrete phase models was performed to predict the efficiency of MSC adhesion in different IPMs. Another combined finite element and CFD analysis based on the mechano-regulation algorithm was performed to predict the influence of IPM on the MrOD of the adhesive MSCs. The results showed that the osteogenesis efficiency of the Voronoi scaffolds increased as the IPM rose from low to moderate and then dropped as the IPM further rose. Same trends were also found in the MSC adhesion and MrOD, which caused by the changes of strain tensors on the strut surface and the tortuosity and fluid velocity of the fluid pathway. Moderate IPM induced the highest osteogenesis efficiency owing to its highest efficiencies of MSC adhesion and MrOD. This work identified the optimal IPM for the osteogenesis of Voronoi scaffolds and clarified its biomechanical mechanisms from the adhesion and mechano-regulated differentiation of MSCs, which is of great importance for guiding Voronoi scaffold design when it is used for bone defect repair.

Robust Thermal Neutron Detection by LiInP2 Se6 Bulk Single Crystals.

Direct neutron detection based on semiconductor crystals holds promise to transform current neutron detector technologies and further boosts their widespread applications. It is, however, long impeded by the dearth of suitable materials in the form of sizeable bulk crystals. Here, high-quality centimeter-sized LiInP2 Se6 single crystals are developed using the Bridgman method and their structure and property characteristics are systematically investigated. The prototype detectors fabricated from the crystals demonstrate an energy resolution of 53.7% in response to α-particles generated from an 241 Am source and robust, well-defined response spectra to thermal neutrons that exhibit no polarization or degradation effects under prolonged neutron/γ-ray irradiation. The primary mechanisms of Se-vacancy and InLi antisite defects in the carrier trapping process are also identified. Such insights are critical for further enhancing the energy resolution of LiInP2 Se6 bulk crystals toward the intrinsic level (≈8.6% as indicated by the chemical vapor transport-grown thin crystals). These results pave the way for practically adopting LiInP2 Se6 single crystals in new-generation solid-state neutron detectors.

Machine-learning assisted scheduling optimization and its application in quantum chemical calculations.

Easy and effective usage of computational resources is crucial for scientific calculations, both from the perspectives of timeliness and economic efficiency. This work proposes a bi-level optimization framework to optimize the computational sequences. Machine-learning (ML) assisted static load-balancing, and different dynamic load-balancing algorithms can be integrated. Consequently, the computational and scheduling engine of the ParaEngine is developed to invoke optimized quantum chemical (QC) calculations. Illustrated benchmark calculations include high-throughput drug suit, solvent model, P38 protein, and SARS-CoV-2 systems. The results show that the usage rate of given computational resources for high throughput and large-scale fragmentation QC calculations can primarily profit, and faster accomplishing computational tasks can be expected when employing high-performance computing (HPC) clusters.

Analysis of surgical strategies and efficacy in the treatment of Os odontoideum with atlantoaxial dislocation.

BACKGROUND: There are many classification systems for atlantoaxial dislocation (AAD). Among these systems, the definitions of irreducible AAD remain vague, and its treatments are not unified. OBJECTIVE: To explore the surgical strategies and efficacy for the treatment of os odontoideum (OO) with AAD. METHODS: The clinical data of 56 OO patients with AAD who underwent surgery from January 2017 to June 2021 were retrospectively analyzed. AAD was classified into four types, Type I and type II were treated with posterior fixation and fusion. Type III received posterior fixation and fusion after irreducible dislocations were converted to reducible dislocations by translateral mass release or transoral release. Type IV required transoral release for conversion into reducible dislocations before posterior fixation and fusion. The operation time, blood loss, and complications were recorded. The preoperative and postoperative neurological function changes were assessed using the Japanese Orthopedic Association (JOA) score. Postoperative fusion status was assessed by X-ray. RESULTS: There were 40 cases of type I-II, 14 cases of type III, and two cases of type IV AAD. The operation times of single posterior fixation and fusion, combined translateral mass release and combined transoral release were 130.52 ± 37.12 min, 151.11 ± 16.91 min and 188.57 ± 44.13 min, the blood loss were 162.63 ± 58.27 mL, 235.56 ± 59.94 mL, 414.29 ± 33.91 mL, respectively. One patient with type III died, one with type III underwent revision surgery due to infection, and three patients with type I had further neurological deterioration after operation. fifty-five patients were followed up for 12-24 months. The follow-up results showed that enough decompression was achieved and that fixation and fusion were effective. The JOA score increased from 9.58 ± 1.84 points preoperative to 13.09 ± 2.68 points at 3 months after operation, 14.07 ± 2.83 points at 6 months and 14.25 ± 2.34 at 12 months after operation, all significant differences compared with preoperative results (P < 0.05). CONCLUSION: OO patients with irreducible AAD can be treated by translateral mass release or transoral release combined with posterior fixation and fusion, while some of those with bony fusion can be treated by transoral release combined with posterior fixation and fusion.

Physical Origin of Negative Differential Resistance in V3 O5 and Its Application as a Solid-State Oscillator.

Oxides that exhibit an insulator-metal transition can be used to fabricate energy-efficient relaxation oscillators for use in hardware-based neural networks but there are very few oxides with transition temperatures above room temperature. Here the structural, electrical, and thermal properties of V3 O5 thin films and their application as the functional oxide in metal/oxide/metal relaxation oscillators are reported. The V3 O5 devices show electroforming-free volatile threshold switching and negative differential resistance (NDR) with stable (<3% variation) cycle-to-cycle operation. The physical mechanisms underpinning these characteristics are investigated using a combination of electrical measurements, in situ thermal imaging, and device modeling. This shows that conduction is confined to a narrow filamentary path due to self-confinement of the current distribution and that the NDR response is initiated at temperatures well below the insulator-metal transition temperature where it is dominated by the temperature-dependent conductivity of the insulating phase. Finally, the dynamics of individual and coupled V3 O5 -based relaxation oscillators is reported, showing that capacitively coupled devices exhibit rich non-linear dynamics, including frequency and phase synchronization. These results establish V3 O5 as a new functional material for volatile threshold switching and advance the development of robust solid-state neurons for neuromorphic computing.