Heteroatom doping has emerged as an effective strategy to enhance the performance of electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Traditional doping methods often involve harsh chemical treatments and tedious procedures, hindering their widespread applications. Furthermore, although dynamic surface reconstruction in alkaline media is commonly observed in bimetallic compounds, strategies to regulate this reconstruction behavior for enhanced HER and OER performances remain inadequately explored. Herein, we report an ultrafast (≤ 300 s) and mild electrochemical doping approach to fabricate Se-doped NiCo2S4 hollow nanoarrays on carbon fiber papers (a-NiCo2(S1−xSex)4), investigating the role of Se in enhancing overall water splitting performance. Under HER conditions, a-NiCo2(S1−xSex)4 demonstrates remarkable stability, with Se tuning the electronic structure to optimize intermediate adsorption and facilitate H2O dissociation. While under OER conditions, Se doping lowers the energy barrier for reconstruction and promotes transformation into active Se, S co-doped Ni0.33Co0.67OOH nanosheets. The optimal samples exhibit superior HER and OER activity, requiring a cell voltage of 1.578 V to deliver a current density of 100 mA·cm−2 for overall water splitting. This work not only introduces a facile method for Se doping but also provides comprehensive insights into the structure–composition–activity relationship for Se-doped bimetallic sulfide.

Phenotypically tolerant persister bacteria can survive antibiotic treatment by entering a metabolically dormant state and are widely recognized as major contributors to infection relapse. To address this challenge, we systematically investigated how the alternating hydrophilic-hydrophobic sequence pattern of polysulfoniums modulate the membrane potential and respiratory activity in dormant bacterial cells. While rifampicin and ampicillin at 25-100 × MIC (mininum inhibitory concentration) were ineffective against persister populations, the PS+(triEG-alt-octyl) alternating polymer significantly reactivated the electron transport chain (ETC) in persister cells, achieving >9-log reductions in viability at 8-16 μg/mL (2-4 × MIC) via precise sequence regulation of hydrophilic and hydrophobic segments. Integration of nanoparticle-assisted delivery with NIR-triggered release enabled efficient penetration of persister-dominated biofilms, resulting in ∼90% biomass clearance and >99.9% elimination of embedded persister cells. These findings highlight the sequence modulation of cationic polymers that offers a highly effective "wake-and-kill" strategy for the eradication of persisters and their associated biofilms.

Gelatin-based bioadhesives, especially methacrylated gelatin (GelMA), have emerged as superior alternatives to sutureless wound closure. Nowadays, their mechanical improvement and therapeutic delivery, particularly for hydrophobic antibiotics, have received ever-increasing interest. Herein, a reinforced gelatin-based hydrogel with a hydrophobic drug delivery property for skin wound treatment was reported. First, photosensitive monomers of N'-(2-nitrobenzyl)-N-acryloyl glycinamide (NBNAGA) were grafted onto GelMA via Michael addition, namely, GelMA-NBNAGA. Second, gelation of the GelMA-NBNAGA solution was accomplished in a few seconds under one step of ultraviolet (UV) light irradiation. Multiple effects were realized simultaneously, including chemical cross-linking initiated by lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), physical cross-linking of uncaged dual hydrogen bonding, and hydrophobic drug release along with o-NB group disintegration. The mechanical properties of the dual-reinforcement hydrogels were verified to be superior to those only with a chemical or physical single-cross-linked network. The hydrophobic anticancer doxorubicin (DOX) and antibiotic rifampicin (Rif) were successfully charged into the hydrogels, separately. The in vitro antimicrobial tests confirmed the antibacterial activity of the hydrogels against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. The in vivo wound-healing assessment in mice further assured their drug release and efficacy. Therefore, this NBNAGA-modified GelMA hydrogel has potential as a material in skin wound dressing with a hydrophobic antibiotic on-demand delivery.

To achieve targeted clearance of bacteria and their biofilms, a straightforward strategy to integrate antimicrobial alternating polymers with photothermal polydopamine nanoparticles (PDA NPs) is proposed. By manipulating the alternating distribution of electrostatic, hydrophobic, and hydrogen bonding units in the polymer backbone, the thermal stability of polymer-particle interaction can be tuned, enabling photothermal-mediated in situ delivery of cationic antimicrobial polymers into bacteria. The alternating polymer coating significantly enhances the penetration capability of NPs into the Methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) biofilm, achieving a 99% bactericidal rate within the biofilm at a low concentration after 10 min of near-infrared irradiation, whereas pristine PDA NPs shows negligible effects. The in-vitro co-culture model demonstrates that alternating-polymer-loaded NPs selectively eradicate 1 x 107 CFU mL-1 of MRSA and E. coli while preserving over 75% viability of the mammalian cells, including mice fibroblasts, human kidney cells, human cervical cancer cells, and macrophages. The efficacy of these biocompatible NPs in targeting bacteria is further validated in a mouse MRSA-infected wound model. This approach represents a significant advancement in developing safe and efficient antimicrobial therapies with targeted bacterial killing and minimal off-target effects based on alternating cationic polymers. Introducing different binding sites alternately into the cationic polymer backbone can precisely modulate the thermal stability of interactions between polymers and photothermal NPs, enabling photothermal-mediated on-off controlled release of the alternating cationic polymers. This straightforward approach equips alternating cationic polymers and photothermal NPs with the unique ability to selectively target and eliminate bacteria while minimizing the impact on mammalian cells. image

Bacterial biofilms and intracellular pathogens pose significant challenges in eradication, often leading to persistent infections that are difficult to treat. To address this issue, the hydrophobic biofilm dispersant D-tyrosine is encapsulated within protein-polycation nanoparticles, designed using a mannose-terminated cationic polymer and concanavalin through electrostatic interactions. Thermodynamic studies reveal that free mannosyl groups on the nanoparticle surface promote spontaneous binding to receptor molecules mimicking those on bacterial biofilms and host cells. Under mildly acidic conditions, the nanoparticles reduce in size from 550 to approximate to 48 nm within 2 h, releasing 76% of encapsulated D-tyrosine. The combination of mannose targeting, particle size reduction, and controlled D-tyrosine release enable the nanoparticles to eliminate 70%-80% of the Pseudomonas aeruginosa and Staphylococcus aureus biofilm biomass at minimum bactericidal concentration (MBC) and 2MBC while eradicating 8 log of bacteria embedded within the biofilm. In an intracellular Pseudomonas aeruginosa infection model using RAW 264.7 macrophages, the nanoparticles at 2MBC eliminate over 95% of the intracellular bacteria without inducing an increase in the inflammatory cytokine interleukin-6. These protein-polycation nanoparticles, which activate their antimicrobial properties under acidic conditions, efficiently penetrate bacterial biofilms and host cell barriers via their mannose-rich surface, offering a promising strategy for the treatment of persistent infections.

Infectiondiseases caused by Gram-negative pathogensare exceedinglydifficult to treat because their characteristic outer membrane limitsantibiotic entry. Herein, we report the development of main-chainpolysulfoniums with different charge densities and amphiphilicitiesbased on the quantitative methylation reaction. By regulating themembrane-disruption capability, the combined efficacy of polysulfoniumsand antibiotic rifampicin can be manipulated from no interaction tosynergy against Gram-negative bacteria Escherichiacoli. After incubating with synergistic polysulfoniums/rifampicincombinations at a minimum inhibitory concentration (MIC), the timeneeded to achieve a 6-log reduction of E. coli can be accelerated 8 times compared to the antibiotic treatment.At 1/2 MIC, polysulfoniums/rifampicin combinations can provide a 90%reduction in biofilm mass and 8-log orders of embedded bacteria killingin 3-day-mature E. coli biofilms. Thiswork demonstrates that alkylation chemistry can serve as a reliablemeans to create antibiotic adjuvants in combating infections causedby Gram-negative pathogens and biofilms.

The stalling development of antibiotics, especially againstintrinsicallyresistant Gram-negative pathogens associated with outer membranes,leads to an emerging antibiotic crisis across the globe. To breathelife into existing drugs, we herein report a hypoxia-responsive nanoparticle(NP) that encapsulates a hydrophobic antibiotic, rifampicin, and acationic potentiator, polysulfonium. The simultaneous release of antibioticsand potentiators can be promoted and inhibited in response to theseverity of bacterial-induced hypoxia, leading to antimicrobial dosingin a precision manner. Under the synergism of polysulfoniums withmembrane-disruption capability, the NPs can intensively decrease theantibiotic dose by up to 66-95% in eliminating planktonic Gram-negative P. aeruginosa bacteria and achieve an 8-log reduction ofbacteria in mature biofilms at rifampicin MIC. The NP formulationdemonstrates that precision dosing of antibiotics and potentiatorsregulated by hypoxia provides a promising strategy to maximize efficacyand minimize toxicity in treating Gram-negative bacterial infection.

Unlike antibiotics with accurate chemical structures, polydisperse chain lengths of synthetic polycations usually result in undesirable variations of antibacterial performance, which obstructs their wide applications in many areas. Herein, we propose that mainchain sulfonium-based polymers with alternating sequences may be used as a potential solution to tackle this issue. Through the thiol- epoxy "click" step-growth polymerization and methylation, alternating polysulfoniums can be facilely prepared with polydispersity around 1.5 and a molecular weight ranging from 6000 to 50 000 g/mol. Within this tested range, constant minimum bactericidal concentration (MBC) values against a broad spectrum of clinically relevant bacteria and stable hemocompatibility are observed for polysulfoniums with different chemical compositions. Moreover, the representative polysulfonium can steadily inhibit the biofilm formation (similar to 75- 90%) at 1.25-5 mu g/mL and achieve 97-99.9% reduction of bacteria at 10-40 mu g/mL in the 3 day mature biofilms. We hypothesize that the amphiphilicity of main-chain polysulfoniums displays less susceptibility to the dispersed polymer chains, probably because of their accurate alternating sequence and the location of all functional groups in the polymer main chain. The unique structural nature of the main-chain sulfonium-based alternating polymers can make them serve as a reliable platform for antibacterial applications in the field of synthetic polycations.

The thorium compounds are promising candidates for the new generation nuclear fuels. Using first-principles and particle swarm optimization methods, we have explored geometrical structures and physical characteristics of thorium carbonitrides (Th2CN) in the extensive pressure range from ambient pressure to 100 GPa. At ambient pressure, we have predicted a new phase I41/amd, which is energetically more favorable than the previously known phases P4/mmm and R3̄m. Moreover, a series of pressure-induced phase transitions have been predicted. The thermodynamics, mechanical stabilities, elastic properties, electronic structures and chemical bonds of all these newly predicted phases have been investigated. Our predictions on the new structures at ambient and high pressures would expand the structural phase diagram of thorium carbonitrides.

Brain functional connectivity (BFC) built from resting-state functional magnetic resonance imaging (rs-fMRI) has shown promising results in revealing the pathological basis of neurological disorders. However, a major problem is that existing approaches tend to limit analysis to a single scale, which unmatches the truth that modern neuroscience highlights BFC as a multi-scale topological architecture. Such a narrow view does lose representation of the inherent BFC topology and would weaken its performance. To solve this issue, we propose a novel triple-pooling graph neural network (TPGNN) to learn different scales of BFC topological knowledge in a task-adaptive way. Specifically, a pooling architecture with triple branches is designed to automate BFC analysis on the global scale, community scale, and region of interest (ROI) scale, respectively. We validate the diagnostic performance of TPGNN on an open autism spectrum disorder (ASD) dataset. Experimental results demonstrate that TPGNN outperforms the alternative state-of-the-art BFC analysis methods and provides potential biomarkers of different scales to benefit neuroscience.

We report on the design and capabilities of a reaction microscope (REMI) end-station at the Shanghai Soft X-ray Free-Electron Laser Facility (SXFEL). This apparatus allows high-resolution and 4π solid-angle coincidence detection of ions and electrons. The components of REMI, including a supersonic gas injection system, spectrometer, detectors and data acquisition system, are described in detail. By measuring the time of flight and the impact positions of ions and electrons on the corresponding detectors, three-dimensional momentum vectors can be reconstructed to study specific reaction processes. Momentum resolutions of ions and electrons with 0.11 a.u. are achieved, which have been measured from a single ionization experiment of oxygen molecules in an infrared (IR), femtosecond laser field, under vacuum at 1.2×10−10 torr, in a reaction chamber. As a demonstration, a Coulomb explosion experiment of oxygen molecules in the IR field is presented. These results demonstrate the performance of this setup, which provides a basic tool for the study of atomic and molecular reactions at SXFEL.

The photoion-photoion coincidence (PIPICO) is a simple and effective approach for the selection of correlated fragments in a specific dissociating channel in molecules. We propose here a charge-encoded multi-photoion coincidence (cMUPICO) method, in analogy to traditional PIPICO, however in which the charge of individual fragments is taken into account. The cMUPICO method allows for clearly displaying coincident channels for dissociation channels containing three more fragments with unequal charge states, invisible in the traditional PIPICO. As a demonstration, three-body fragmentation dynamics of CO2 in strong IR laser fields is analyzed, and 11 dissociation channels are effectively identified, five of which are first found with cMUPICO. The present results show that cMUPICO is a powerful and practical tool for distinguishing various dissociation channels with multiply charged multi-photoions.

Multi-ionization and subsequent Coulomb explosion (CE) of the N2O molecule irradiated by a linearly polarized 800 nm laser field is investigated by a reaction microscope, where a number of CE channels of N2Oq+ with q ≤ 5 for two-body fragmentation and q ≤ 8 for three-body fragmentation were observed. For two-body CE, by analyzing the internuclear separations extracted from kinetic energy releases (KERs), dissociation branching fractions, and laser intensity dependence, interestingly, we found that fragmentation N2O5+ → N3+ + NO2+ is produced directly from dissociating N2O3+ via non-sequential stairstep ionization, whereas most of the others result from the sequential stairstep ionization. For three-body CE, 25 fragmentation channels of N2Oq+ (q = 3-8) are distinguished in the present charge-encoded multi-photoion coincidence plot, and the concerted fragmentation mechanism is nominated in a typical Dalitz plot. With the help of the numerical computation with the measured KERs and momentum correlation angles, the geometric structures of molecular ions prior to fragmentation are reconstructed, which display the bending motion and simultaneous two-bond stretching before the CE. Increasing of the bond length for high charged N2Oq+ indicates the dominating stairstep ionization in the three-body fragmentation.

BackgroundThe research of molecular fragmentation dynamics has attracted extensive attention in the fields of physics, chemistry and biology. The major challenge in this field is to understand the selectivity of molecular bond breaking and to elucidate which parameters control bond fission.PurposeThis study aims to reveal the mechanism of two and three-body fragmentation of CO2 in strong laser fields and to elucidate the dynamics information of the ion fragmentation in the Coulomb explosion.MethodsThe time-of-flight (TOF) and three-dimensional momentum distributions of ion fragments were obtained using a cold-target recoil ion momentum spectroscopy (COLTRIMS). Precise identification of the two-body and three-body dissociation channels of CO2 was determined by the photoion-photoion coincidence (PIPICO) and the photoion-photoion-photoion coincidence (PIPIPICO) techniques. The occurrence of sequential and non-sequential fragmentation during three-body dissociation was revealed by the momentum correlation between two O ions. Finally, the dynamics of the three-body fragmentation process was visualized by the Newton diagram.ResultsFour two-body dissociation channels and three three-body dissociation channels for CO2q+ (q≤4) are identified with the coincidence technique. The kinetic energy release (KER) distribution of these dissociation channels is obtained from the three-dimensional momentum.ConclusionsThe experiments reveal that the dynamic collimation mechanism plays a dominant role in the two-body fragmentation channels, and the ion fragments of the four two-body fragmentation channels are mainly emitted along the laser polarization direction with the significant anisotropic distribution. Non-sequential and sequential fragmentation of CO2 is separated and identified in the momentum correlation and Newtonian diagrams. In the first step of the sequential fragmentation of CO24+, the O2+ and CO2+ ionic fragments are always produced. It is further shown that the vibration and rotation of the CO2+ ion are shown to occur before the fragmentation of the second step.

BackgroundTransition metal nitrogen doped carbon materials are promising to replace precious metal platinum-based materials as an important electrocatalyst for oxygen reduction, and have attracted extensive attention in the research fields of energy storage materials and energy conversion devices.PurposeThis study aims to develop new vanadium doped transition metal carbon materials with excellent catalytic performance, and clarify the role of the introduced of vanadium.MethodsThe vanadium doped cobalt-nitrogen-carbon catalyst was designed by two-step pyrolysis method and impregnation method. The catalytic performance of the oxygen reduction reaction (ORR) was evaluated by a three electrode system using rotating disk electrode. The morphology and microstructure of catalysts were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) was employed to examine crystal orientation structure of catalyst whilst the element types and distribution of materials was analyzed by X-ray photoelectron spectroscopy. Finally, Co K-edge and V K-edge X-ray absorption fine structure (XAFS) spectroscopy were used to determine the local atomic configuration and electronic structure.ResultsThe experimental results show that vanadium doped cobalt-nitrogen-carbon catalyst exhibits superior ORR performance than the traditional cobalt‒nitrogen‒carbon catalyst. XAFS spectra clarifies that the electronic state of cobalt is changed by the introduction of vanadium, and the catalytic performance is further enhanced.ConclusionThe performance of Co‒N‒C catalyst is regulated by the high-valence state V doping, which provides an idea for the design of high-efficiency oxygen reduction catalyst.

Incorporation of cationic groups into polymers represents one of the most widely used strategies to prepare antibacterial materials. Sulfonium, as a typical cationic moiety, displays potent antibacterial efficacy in the form of small molecules, however, has long underperformed in polymeric systems. Herein, we developed a series of alternating polysulfoniums, where the hydrophobicity of each alternating unit can be accurately tuned by altering the monomer precursors. Excellent antibacterial activity against a broad spectrum of clinically relevant bacteria, including Methicillin-resistant Staphylococcus aureus, can be obtained in the optimal compositions with minimum bactericidal concentrations in the range of 1.25-10 μg/mL, as well as negligible hemolytic effect at polymer concentrations even up to 10000 μg/mL. Bacteria do not readily develop resistance to polysulfoniums due to the antibacterial action is possibly the membrane disrupting mechanism. This work demonstrates sulfonium-based polymers with well-defined sequences can function as a promising candidate to combat drug-resistant bacterial infection.

The effects of alloy surface composition and pre-adsorbed oxygen on the behaviors of H2O over Ni–Cr binary alloy surfaces were investigated by using the first-principles method. The surface energies and work functions for a series of Ni–Cr (111) alloy surfaces with different Cr concentrations were addressed to track the surface reactivities. An enhancement effect on the surface reactivity from Cr doping in the top-surface layer (TSL) of nickel substrates was identified. The locations of Cr in the TSL dramatically promoted exothermic adsorption of H2O and its decomposed products, including OH, O, and H. The calculated potential dissociation pathways further demonstrated that the successive dissociation of H2O molecules was substantially triggered in the presence of Cr doping in the TSL. By contrast, the Cr doping in the sub-surface layer hindered the dehydrogenation of H2O with a relatively higher energy barrier for OH dissociation. Moreover, with pre-adsorbed oxygen atoms closer to Cr, the first elementary step of H2O dissociation was easily fostered, whereas the OH dissociation was hindered. The Cr doping and O pre-adsorption accelerated the dissociation of H2O, which plays a critical role in the initial oxidation of nickel-based alloys in water- or oxygen-bearing environments.

Un fullerène est une molécule de carbone sous la forme d’une sphère creuse, d’un ellipsoïde, d’un tube et de nombreuses autres formes. Les fullerènes sphériques, également appelés Buckminsterfullerenes ou buckyballs, ressemblent aux balles utilisées dans le football association. Les fullerènes cylindriques sont également appelés nanotubes de carbone (Buckytubes). Les fullerènes sont semblables à la structure au graphite, qui est composé de feuilles de graphène empilées d’anneaux hexagonaux liés. Ils sont cylindriques, ils doivent donc contenir des anneaux pentagonaux (ou parfois heptagonaux).

Accelerator-based ion-beam irradiation has been widely used to mimic the effects of neutron radiation damage in nuclear reactors. However, ion radiation is most often monodisperse in the incoming ions’ momentum direction, leading to excessive polarization in defect distribution, while the scattering under neutron irradiation is often more isotropic and has less radiation-induced polarization. Mitigation of the excess-polarization as well as the damage non-uniformity artifact might be crucial for making the simulation of neutron radiation by ion-beam radiation more realistic. In this work, a general radiation polarization theory in treating radiation as external polar stimuli is established to understand the natural material responses in different contexts, and the possibility to correct the defect polarization artifact in ion-beam irradiation. Inspired by Magic Angle Spinning in Nuclear Magnetic Resonance, we present a precise sample spinning strategy to reduce the point-defect imbalance effect in ion-beam irradiation. It can be seen that with optimized surface inclination angle and the axis of sample rotation, the vacancy-interstitial population imbalance, as well as the damage profile non-uniformity in a designated region in the target are both reduced. It is estimated that sample spinning frequency on the order of kHz should be sufficient to scramble the ion momentum monodispersity for commonly taken ion fluxes and dose rates, which is experimentally feasible.

When sensor networks for the Internet of Things (IoT) are applied on a large scale, it's urgent to investigate self-powered photoelectric detection system without external power supply. Therefore, we propose a self-powered photo-detection system based on the triboelectric nanogenerator (TENG) in which the silicon PIN photodetector is powered by a paper-based contact separated TENG. The silicon PIN photodetectors are based on mature silicon processing technology, which is suitable for large scale production. The TENG is connected to the detector through the rectifier bridge circuit. Owing to the internal photoelectric effect of the detector and the TENG impedance matching effect, the equivalent resistance of the detector decreases when light is applied to the surface of the photodetector and the output voltage of the TENG changes accordingly. We investigate the output characteristics of the photoelectric detection system under different illumination intensities and propose a circuit model to analyze the influence of the current on the detection range. Finally, we use light-emitting diodes (LEDs) as display devices to characterize the detected light intensity for applicable self-powered photo-detection system.