Type II and IV toxin-antitoxin systems coordinately stabilize the integrative and conjugative element of the ICESa2603 family conferring multiple drug resistance in Streptococcus suis.

Integrative and conjugative elements (ICEs) play a vital role in bacterial evolution by carrying essential genes that confer adaptive functions to the host. Despite their importance, the mechanism underlying the stable inheritance of ICEs, which is necessary for the acquisition of new traits in bacteria, remains poorly understood. Here, we identified SezAT, a type II toxin-antitoxin (TA) system, and AbiE, a type IV TA system encoded within the ICESsuHN105, coordinately promote ICE stabilization and mediate multidrug resistance in Streptococcus suis. Deletion of SezAT or AbiE did not affect the strain's antibiotic susceptibility, but their duple deletion increased susceptibility, mainly mediated by the antitoxins SezA and AbiEi. Further studies have revealed that SezA and AbiEi affect the genetic stability of ICESsuHN105 by moderating the excision and extrachromosomal copy number, consequently affecting the antibiotic resistance conferred by ICE. The DNA-binding proteins AbiEi and SezA, which bind palindromic sequences in the promoter, coordinately modulate ICE excision and extracellular copy number by binding to sequences in the origin-of-transfer (oriT) and the attL sites, respectively. Furthermore, AbiEi negatively regulates the transcription of SezAT by binding directly to its promoter, optimizing the coordinate network of SezAT and AbiE in maintaining ICESsuHN105 stability. Importantly, SezAT and AbiE are widespread and conserved in ICEs harbouring diverse drug-resistance genes, and their coordinated effects in promoting ICE stability and mediating drug resistance may be broadly applicable to other ICEs. Altogether, our study uncovers the TA system's role in maintaining the genetic stability of ICE and offers potential targets for overcoming the dissemination and evolution of drug resistance.

Multi-depot routing problem with van-based driverless vehicles.

In order to strengthen the coordination between different delivery participants and means of transport, this work proposes one extension of multi-depot routing problems where vans and driverless vehicles are used in combination during the delivery. The operation process mainly includes two parts. One is that, vans carry several driverless vehicles and goods, and drop off or pick up driverless vehicles at stops. Another is that, driverless vehicles departing directly from depots and dropped off by vans deliver goods to customers in cooperation. During the delivery, vans and driverless vehicles are in close cooperation through the proposed multi-depot joint distribution and the proposed van-van joint distribution. By the two modes, one van can depart from one depot and return to another depot, and one driverless vehicle can be set off by one van at one stop and be picked up by another van at another stop. This multi-depot routing problem with van-based driverless vehicles is formulated as a mixed integer programming model which can be solved by a designed heuristic algorithm. The sensitivity analyses about the maximum number of driverless vehicles in one van and the maximum traveling time of driverless vehicles are also performed. The results reveal that they have limited effects on the delivery cost and the application of the two modes. In addition, the experimental results demonstrate that the application of the two modes is affected by the distribution of depots and stops.

Failure of Lithium-Ion Batteries Accelerated by Gravity.

The safety concerns surrounding lithium-ion batteries (LIBs) have garnered increasing attention due to their potential to endanger lives and incur significant financial losses. However, the origins of battery failures are diverse, presenting significant challenges in developing safety measures to mitigate accidental catastrophes. In this study, the aging mechanism of LiNi0.5Co0.2Mn0.3O2||graphite-based cylindrical 18,650 LIBs stored at room temperature for two years was investigated. It was found that an uneven distribution of electrolytes can be caused by gravity, leading to temperature variations within the battery. Specifically, it was observed that the temperature at the top of the battery was approximately -0.89 °C higher than at the bottom, correlating with an increase in partial internal resistance. Additionally, upon disassembly and analysis of spent batteries, the most significant damage to electrode materials at the top of the battery was observed. These findings suggest that gravity-induced electrolyte insufficiency exacerbates side reactions, particularly at the top of the battery. This study offers a unique perspective on the safety concerns associated with high-energy-density batteries in long-term and large-scale applications.

Simultaneous stabilization of particulate and bioavailable arsenic in soils from the realgar mining area by polyacrylamide, nano-SiO2, and ferrihydrite composite materials.

Arsenic (As) contamination in realgar mining areas poses a severe environmental and health risk, highlighting the critical need for effective strategies to manage As migration, particularly in its particulate and bioavailable states. Soil erosion and water leaching serve as significant pathways for spreading As, emphasizing the imperative to curtail its mobility. In the present study, we proposed an effective strategy that combines the utilization of polyacrylamide (PAM), nano-SiO2 (NS), and ferrihydrite (Fh) to elevate the stability of As in soils from a realgar mining area. The results show that this composite material demonstrates the capability to concurrently regulate soil erosion and mitigate the leaching of bioavailable As. The combination of the three materials in the proportion of 0.5 % PAM +0.1 % NS + 1.0 % Fh can reduce the soil particulate and bioavailable As content by 99.11 % and 93.98 %, respectively. The unconfined compressive strength of the soil can be increased by about 30 % under this condition. The SEM analyses show that the addition of PAM and NS can significantly enhance the aggregation of soil particles and then reduce the soil erosion rate. These findings highlight the significant potential of the proposed approach in mitigating As contamination in soil within mining environments. The approach offers a sustainable and comprehensive solution to address the transport of heavy metal contaminants in both particulate and bioavailable states in mining areas.

Iodide and sulfite synergistically accelerate the photo-reduction and recovery of As(V) and As(III) in sulfite/iodide/UV process: Efficiency and mechanism.

Photo-reduction of arsenic (As) by hydrated electron (eaq-) and recovery of elemental arsenic (As(0)) is a promising pathway to treat As-bearing wastewater. However, previously reported sulfite/UV system needs large amounts of sulfite as the source of eaq-. This work suggests a sulfite/iodide/UV approach that is more efficient and consumes much less chemical reagents to remove As(III) and As(V) and recover valuable As(0) from wastewater, hence preventing the production of large amounts of As-containing hazardous wastes. Our results showed that more than 99.9% of As in the aqueous phase was reduced to highly pure solid As(0) (>99.5 wt%) by sulfite/iodide/UV process under alkaline conditions. Sulfite and iodide worked synergistically to enhance reductive removal of As. Compared with sulfite/UV, the addition of iodide had a substantially greater effect on As(III) (over 200 times) and As(V) (approximately 30 times) removals because of its higher absorptivity and quantum yield of eaq-. Furthermore, more than 90% of the sulfite consumption was decreased by adding a small amount of iodide while maintaining similar reduction efficiency. Hydrated electron (eaq-) was mainly responsible for As(III) and As(V) reductions and removals under alkaline conditions, while both SO3•- and reactive iodine species (e.g., I•, I2, I2•-, and I3-) may oxidize As(0) to As(III) or As(V). Acidic circumstances caused sulfite protonation and the scavenging of eaq- by competing processes. Dissolved oxygen (O2) and CO32- prevented As reduction by light blocking or eaq- scavenging actions, but Cl-, Ca2+, and Mg2+ showed negligible impacts. This study presented an efficient method for removing and recovering As from wastewater.

Surface Reconstruction of High-Voltage LiNi0.5Mn1.5O4 Cathode via the Sculpture Method toward Enhanced Stability.

High-voltage LiNi0.5Mn1.5O4 (LNMO) cathodes suffer from severe capacity degradation during long-term cycling due the manganese dissolution and their high operating voltage (∼4.95 V), which pose serious challenges at the surface or interface. Moreover, both traditional ion-doping and passivation layer coating are difficult to apply consistently to LNMO cathode because of their complicated procedures, especially in large-scale production. To address these issues, a strategy employing HNO3/H2O2 leaching in synergy with a sintering process at a mid-temperature of 700 °C was used to achieve selective surface reconstruction. An optimal ratio of reactants was applied to balance the capacity and the cyclic stability of the LNMO cathode. The optimized valence composition of Mn on the material surface mitigates the occurrence of Jahn-Teller distortion, accompanied by a reasonable ratio of ordered and disordered phases and the concentration of oxygen vacancies after sintering, which improves the interface behavior between the electrode and electrolyte. This method delivers a high reversible capacity of 116.5 mAh g-1 after 200 cycles at 0.5 C (1 C = 147 mAh g-1) with a capacity retention of 91.30% and 110 mAh g-1 with a remarkably high capacity retention of 86.85% after 500 cycles at 2 C. This balanced approach, utilizing the protective effects of oxidation (O22-) and the erosive action of acid (H+), is proposed to achieve regional surface reconstruction of advanced LNMO cathode. This opens up a strategy for improving oxide-based cathode materials with low cost and mass production capability, especially favoring high consistency.

Correction: Expanded graphite incorporated with Li4Ti5O12 nanoparticles as a high-rate lithium-ion battery anode.

[This corrects the article DOI: 10.1039/D4RA00832D.].

Expanded graphite incorporated with Li4Ti5O12 nanoparticles as a high-rate lithium-ion battery anode.

Due to their small interlayer spacing and a low lithiation potential close to Li+ deposition, current graphite anodes suffer from weak kinetics, and lithium deposition in a fast-charging process, hindering their practical application in high-power lithium-ion batteries (LIBs). In this work, expanded graphite incorporated with Li4Ti5O12 nanoparticles (EG/LTO) was synthesized via moderate oxidization of artificial graphite following a solution coating process. The EG/LTO has sufficient porosity for fast Li+ diffusion and a dense Li4Ti5O12 layer for decreased interface reaction resistance, resulting in excellent fast-charging properties. EG/LTO presented a high reversible capacity of 272.8 mA h g-1 at 3.74 A g-1 (10C), much higher than that of the original commercial graphite (50.1 mA h g-1 at 10C) and even superior to that of hard carbon. In addition, EG/LTO exhibited capacity retention rate of 98.4% after 500 cycles at 10C, demonstrating high structural stability during a long cycling process. This study provides a protocol for a solution chemistry method to prepare fast-charging graphite anode materials with high stability for high-power LIBs.

Oriented Gradient Doping of Zirconium in Ni-Rich Cathode to Achieve Ultrahigh Stability and Rate Capability.

Ni-rich layered oxide materials exhibit great prospects for practical applications in lithium-ion batteries due to their high specific capacity. However, the poor cycling performance and suboptimal rate performance have caused obstacles for their widespread application. Herein, we developed a gradient Zr element doping method based on the bulk gradient concentration of Ni-rich layered oxide material to reinforce the cycle stability and rate performance of the cathode. In particular, the orientations of the gradient Zr doping were achieved via coprecipitation in a positive or negative correlation between the concentrations of Zr and Ni, and it was revealed that the material behaves better when the Zr content is abundant in the core. The gradient doping of Zr decreases the content of Ni2+ and mitigates the mixing degree of Li+ and Ni2+, implying the superior performance of doped cathode material. Compared with the bare sample (70.7%, 121.4 mAh g-1), the Zr-doped sample delivered a higher capacity retention of 85.6% after 300 cycles at 1C (1C = 180 mA g-1) and exhibited a considerable rate performance of 122.5 mAh g-1 at 20C. In particular, the Zr-doped cathodes performed dramatically on high rate cycling at 10C, with an initial capacity of 143.6 and 103.9 mAh g-1 after 300 cycles. Furthermore, the Zr-doped cathode delivered significant stability at a high potential of 4.5 V with a capacity retention of 72.1% after 300 cycles, while that of the bare sample was only 37.4%. The concept of gradient doping strategies during coprecipitation offers new insight into the design of advanced cathodes with excellent cycling stability and rate capability.

One-Step Synthesis of LiCo1-1.5xYxPO4@C Cathode Material for High-Energy Lithium-ion Batteries.

Intrinsically low ion conductivity and unstable cathode electrolyte interface are two important factors affecting the performances of LiCoPO4 cathode material. Herein, a series of LiCo1-1.5xYxPO4@C (x = 0, 0.01, 0.02, 0.03) cathode material is synthesized by a one-step method. The influence of Y substitution amount is optimized and discussed. The structure and morphology of LiCo1-1.5xYxPO4@C cathode material does not lead to obvious changes with Y substitution. However, the Li/Co antisite defect is minimized and the ionic and electronic conductivities of LiCo1-1.5xYxPO4@C cathode material are enhanced by Y substitution. The LiCo0.97Y0.02PO4@C cathode delivers a discharge capacity of 148 mAh g-1 at 0.1 C and 96 mAh g-1 at 1 C, with a capacity retention of 75% after 80 cycles at 0.1 C. Its good electrochemical performances are attributed to the following factors. (1) The uniform 5 nm carbon layer stabilizes the interface and suppresses the side reactions with the electrolyte. (2) With Y substitution, the Li/Co antisite defect is decreased and the electronic and ionic conductivity are also improved. In conclusion, our work reveals the effects of aliovalent substitution and carbon coating in LiCo1-1.5xYxPO4@C electrodes to improve their electrochemical performances, and provides a method for the further development of high voltage cathode material for high-energy lithium-ion batteries.

Three-Dimensional and Mesopore-Oriented Graphene Conductive Framework Anchored with Nano-Li4Ti5O12 Particles as an Ultrahigh Rate Anode for Lithium-Ion Batteries.

Because of the disadvantages of commercial graphite anodes for high-power lithium-ion batteries, a kind of spinel nanolithium titanate (Li4Ti5O12)/graphene microsphere composite [denoted as LTO/reduced graphene oxide (rGO)] is successfully synthesized. The as-prepared composite is made up of curled graphene sheets which are anchored with nano-Li4Ti5O12 particles. These nano-Li4Ti5O12 particles are uniformly decorated on the conductive graphene framework and their sizes range from just 15 to 20 nm. In the as-prepared composite, the curled graphene sheets form a unique mesopore-oriented structure which provides plenty of three-dimensional channels for ion transportation. These structure characters greatly improve both the electron conductivity and Li+ diffusion ability. The ratio of pseudocapacitive capacity dramatically increases in the obtained LTO/rGO composite and generates excellent ultrahigh rate performances. The as-prepared LTO/rGO composite delivers a reversible capacity of 70.3 mA h g-1 at 200 C and a capacity retention of 84.7% after 1000 cycles at 50 C. As the current density varies from 30 to 100 C, the special capacity remains unchanged (about 112 mA h g-1). These results show that the graphene framework-supported nano-Li4Ti5O12 composite has potential application in high-power lithium-ion batteries.

Lithiophilic-lithiophobic gradient interfacial layer for a highly stable lithium metal anode.

The long-standing issue of lithium dendrite growth during repeated deposition or dissolution processes hinders the practical use of lithium-metal anodes for high-energy density batteries. Here, we demonstrate a promising lithiophilic-lithiophobic gradient interfacial layer strategy in which the bottom lithiophilic zinc oxide/carbon nanotube sublayer tightly anchors the whole layer onto the lithium foil, facilitating the formation of a stable solid electrolyte interphase, and prevents the formation of an intermediate mossy lithium corrosion layer. Together with the top lithiophobic carbon nanotube sublayer, this gradient interfacial layer can effectively suppress dendrite growth and ensure ultralong-term stable lithium stripping/plating. This strategy is further demonstrated to provide substantially improved cycle performance in copper current collector, 10 cm2 pouch cell and lithium-sulfur batteries, which, coupled with a simple fabrication process and wide applicability in various materials for lithium-metal protection, makes the lithiophilic-lithiophobic gradient interfacial layer a favored strategy for next-generation lithium-metal batteries.