Nonstoichiometry Induced Amorphous Grain Boundary of Na5SmSi4O12 Solid-State Electrolyte for Long-Life Dendrite-Free Sodium Metal Battery.

Oxide ceramics are considered promising candidates as solid electrolytes (SEs) for sodium metal batteries. However, the high sintering temperature induced boundaries and pores between angular grains lead to high grain boundary resistance and pathways for dendrite growth. Herein, we report a grain boundary modification strategy, which in situ generates an amorphous matrix among Na5SmSi4O12 oxide grains via tuning the chemical composition. The mechanical properties as well as electron mitigating capability of modified SE have been significantly enhanced. As a result, the SE achieves a room-temperature total ionic conductivity of 5.61 mS cm-1, the highest value for sodium-based oxide SEs. The Na|SE|Na symmetric cell achieves a high critical current density of 2.5 mA cm-2 and excellent cycle life over more than 2800 h at 0.15 mA cm-2 without dendrite formation. The full cell with Na3V2(PO4)3 as the cathode demonstrates impressive cycling performance, maintaining stability over 3000 cycles at 5C without observable loss of capacity.

Model test study on the mechanical response of the deep buried tunnel lining.

Deep-buried tunnels with weak surrounding rock are frequently encountered issues in traffic engineering. It plays an important role in the excavation process and the project operation. This paper applies the theoretical analysis and laboratory test related to four different conditions in terms of their thickness to determine the mechanical response of deep-buried tunnel lining. Then, the energy dissipative structure theory is employed to explain the experimental results. This paper has made the following achievements: firstly, it is found that the toughness of the secondary lining was found to be often the most important indicator of tunnel safety, with better-toughness linings having higher tensile strength and crack resistance. Secondly, it suggests that the inclusion of steel reinforcement in the concrete lining can effectively improve the secondary lining toughness. Finally, it proves that the more ductile liner had more energy, higher load-carrying capacity, and was better able to maintain the overall stability of the structure.

Engineering Detrimental Functional Groups in Conductive Additives Toward High-Performance All-Solid-State Batteries.

Conductive additives are of great importance for the adequate utilization of active materials in all-solid-state lithium batteries by establishing conductive networks in the composite cathode. However, it usually causes severe interfacial side reactions with solid electrolytes, especially sulfide electrolytes, leading to sluggish ion transportation and accelerated performance degradation. Herein, a simple hydrogen thermal reduction process is proposed on a commonly used conductive additive Super P, which effectively removes the surface oxygen functional groups and weakens the interfacial side reactions with sulfide. With a small amount of 1 wt % reduced Super P, ASSLBs demonstrates a competitive capacity of 180.2 mAh g-1, which is much higher than the 130.8 mAh g-1 of untreated Super P. Impressively, reduced Super P based ASSLBs also exhibit a higher capacity retention of 81.8 % than 64.6 % of untreated Super P. The cathode interfacial chemical evolutions reveal that reduced Super P could effectively alleviate the side reactions of sulfide. Reduced Super P shows better reversible capacity compared to reduced carbon nanofiber with almost no loss of capacity retention, due to its more complete conductive network. Our results highlight the importance of oxygen-containing functional groups for conductive additives, lightening the prospect of low-cost 0D conductive additives for practical ASSLBs.

Electrochemically induced crystalline-to-amorphization transformation in sodium samarium silicate solid electrolyte for long-lasting sodium metal batteries.

Exploiting solid electrolyte (SE) materials with high ionic conductivity, good interfacial compatibility, and conformal contact with electrodes is essential for solid-state sodium metal batteries (SSBs). Here we report a crystalline Na5SmSi4O12 SE which features high room-temperature ionic conductivity of 2.9 × 10-3 S cm-1 and a low activation energy of 0.15 eV. All-solid-state symmetric cell with Na5SmSi4O12 delivers excellent cycling life over 800 h at 0.15 mA h cm-2 and a high critical current density of 1.4 mA cm-2. Such excellent electrochemical performance is attributed to an electrochemically induced in-situ crystalline-to-amorphous (CTA) transformation propagating from the interface to the bulk during repeated deposition and stripping of sodium, which leads to faster ionic transport and superior interfacial properties. Impressively, the Na|Na5SmSi4O12|Na3V2(PO4)3 sodium metal batteries achieve a remarkable cycling performance over 4000 cycles (6 months) with no capacity loss. These results not only identify Na5SmSi4O12 as a promising SE but also emphasize the potential of the CTA transition as a promising mechanism towards long-lasting SSBs.

Binary Metallic CuCo5 S8 Anode for High Volumetric Sodium-Ion Storage.

With the rapid improvement of compact smart devices, fabricating anode materials with high volumetric capacity has gained substantial interest for future sodium-ion batteries (SIBs) applications. Herein, a novel bimetal sulfide CuCo5 S8 material is proposed with enhanced volumetric capacity due to the intrinsic metallic electronic conductivity of the material and multi-electron transfer during electrochemical procedures. Due to the intrinsic metallic behavior, the conducting additive (CA) could be removed from the electrode fabrication without scarifying the high rate capability. The CA-free CuCo5 S8 electrode can achieve a high volumetric capacity of 1436.4 mA h cm-3 at a current density of 0.2 A g-1 and 100 % capacity retention over 2000 cycles in SIBs, outperforming most metal chalcogenides, owing to the enhanced electrode density. Reversible conversion reactions are revealed by combined measurements for sodium systems. The proposed new strategy offers a viable approach for developing innovative anode materials with high-volumetric capacity.

High-Entropy Solid-State Na-Ion Conductor for Stable Sodium-Metal Batteries.

Solid-state sodium-metal batteries (SSBs) hold great promise for their merits in low-cost, high energy density, and safety. However, developing solid electrolyte (SE) materials for SSBs with high performance is still a great challenge. In this study, high-entropy Na4.9 Sm0.3 Y0.2 Gd0.2 La0.1 Al0.1 Zr0.1 Si4 O12 was synthesized at comparatively low sintering temperature of 950 °C with high room-temperature ionic conductivity of 6.7×10-4  S cm-1 and a low activation energy of 0.22 eV. More importantly, the Na symmetric cells using high-entropy SE show a high critical current density of 0.6 mA cm-2 , outstanding rate performance with fairly flat potential profiles at 0.5 mA cm-2 and steady cycling over 700 h under 0.1 mA cm-2 . Solid-state Na3 V2 (PO4 )3 ||high-entropy SE||Na batteries are further assembled manifesting a desirable cycling stability with almost no capacity decay after 600 cycles and high Columbic efficiency over 99.9 %. The findings present opportunities for the design of high-entropy Na-ion conductors toward the development of SSBs.

Interfacial Engineering Boosts Highly Reversible Zinc Metal for Aqueous Zinc-Ion Batteries.

Zinc metal is emerging as the promising anode for aqueous Zn-ion batteries. However, corrosion and undesirable Zn dendrite growth limit their practical application in the large-scale energy storage area. Herein, a mountain-valley micro/nanostructure is successfully fabricated on the surface of the Zn anode via a femtosecond-laser filament texturing (FsLFT) technique. Beneficial from the large surface area and spontaneously generated ZnO coating layer, the FsLFT-Zn electrode demonstrates a slow corrosion rate with a current density of 0.62 mA cm-2 and a stable cycle life over 3000 h under 1 mA cm-2, superior to the original Zn anode. Simulation of the electric fields reveals that the enlarged surface area is responsible for the outstanding performance of the FsLFT-Zn electrode. This study not only proposes a novel strategy to suppress dendrite growth toward highly stable AZIBs but also opens a new avenue to solve similar issues in other metal batteries.

Study on stress variation of advance fiberglass anchor bolts during tunnel excavation process.

One of the main causes for excessive deformation within a tunnel is due to the instability of the soil or soft rock ahead of the excavation face. Fiberglass bolts have been shown to be a useful advance reinforcement method for the excavation face. In this paper, an improved ADECO-RS (Analysis of controlled deformation in rock and soils) method had been proposed for soft rock mountain tunnels, in terms of the partial (mainly the upper bench) excavation face reinforcement and also for the bench excavation method. Strain gauges were used to test the micro-strain in the fiberglass bolt to investigate how the axial force of the fiberglass bolt varied during the tunnel excavation. In addition, combined with the field tunnel deformation monitoring data, the relationship between the reinforcement parameters of the fiberglass bolts and the tunnel construction phase were discussed. The research results show that: (1) The stress state of the anchor rod is related to the reinforcement length of the anchor rod; (2) Excavation within the lap area of the fiberglass bolt leads to an increase in the axial force of the bolt, while excavation outside the lap area of the fiberglass bolt has no effect on the anchor; (3) Reducing the reinforcement area of rock mass will affect the stability of the excavation. To ensure the stability of the excavation face, the initial support construction loop should be completed as soon as possible; (4) In a future project with similar conditions, the recommended lap length of the fiberglass bolt could be 3 m utilizing the fiberglass bolt grouting face reinforcement method.

Quantitative Regulation of Interlayer Space of NH4 V4 O10 for Fast and Durable Zn2+ and NH4 + Storage.

Layered vanadium-based oxides are the promising cathode materials for aqueous zinc-ion batteries (AZIBs). Herein, an in situ electrochemical strategy that can effectively regulate the interlayer distance of layered NH4 V4 O10 quantitatively is proposed and a close relationship between the optimal performances with interlayer space is revealed. Specifically, via increasing the cutoff voltage from 1.4, 1.6 to 1.8 V, the interlayer space of NH4 V4 O10 can be well-controlled and enlarged to 10.21, 11.86, and 12.08 Å, respectively, much larger than the pristine one (9.5 Å). Among them, the cathode being charging to 1.6 V (NH4 V4 O10 -C1.6), demonstrates the best Zn2+ storage performances including high capacity of 223 mA h g-1 at 10 A g-1 and long-term stability with capacity retention of 97.5% over 1000 cycles. Such superior performances can be attributed to a good balance among active redox sites, charge transfer kinetics, and crystal structure stability, enabled by careful control of the interlayer space. Moreover, NH4 V4 O10 -C1.6 delivers NH4 + storage performances whose capacity reaches 296 mA h g-1 at 0.1 A g-1 and lifespan lasts over 3000 cycles at 5 A g-1 . This study provides new insights into understand the limitation of interlayer space for ion storage in aqueous media and guides exploration of high-performance cathode materials.

Bimetallic CuSbSe2 : A Potential Anode Material for Sodium and Lithium-Ion Batteries with High-Rate Capability and Long-Term Stability.

Bimetallic transition metal chalcogenides (TMCs) materials have emerged as attractive anodes for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of the high intrinsic electronic conductivity, rich redox sites and unique reaction mechanism. In this work, we report the synthesis and electrochemical properties of a novel bimetallic TMCs material CuSbSe2 . The as-prepared anode delivers a high reversible capacity of 545.6  mA h g-1 for SIBs and 592.6  mA h g-1 for LIBs at a current density of 0.2 A g-1 , and an excellent rate capability of 425.9  mA h g-1 at 20 A g-1 for SIBs and 226.0  mA h g-1 at 10 A g-1 for LIBs without any common-used surface modification or carbonaceous compositing. In addition, ex situ X-ray diffraction (XRD) and High-resolution transmission electron microscopy (HRTEM) reveal a combined conversion-alloying reaction mechanism of LIBs and NIBs. Our findings suggest bimetallic CuSbSe2 could be a potential anode material for both SIBs and LIBs.

A strong and tough gelatin/polyvinyl alcohol double network hydrogel actuator with superior actuation strength and fast actuation speed.

Hydrogels are widely used in actuators that are applied in numerous fields such as multifunctional sensors, soft robots, artificial muscles, manipulators and microfluidic valves, and yet their applications in soft robots and artificial muscles are often limited by low actuation strength and slow actuation speed. Here, we develop a hydrogel actuator with high actuation strength (contraction strength of 850 kPa), fast actuation speed (response time of 90 s) and high energy density (output working density of 72 kJ m-3) by introducing a storing-releasing elastic potential energy method into a double network hydrogel. The high actuation strength is owing to the double network hydrogel, which possesses a high elastic modulus of 1.3 MPa, fracture strength of 1.8 MPa, and fracture energy of 16 kJ m-2. The fast actuation speed is due to the storing-releasing elastic potential energy method, which stretches the hydrogel and locks the hydrogel at deformed shape under external stimuli to store the elastic potential energy and then makes the hydrogel contract rapidly under new stimuli to release the pre-stored energy. A capture actuator and a hand muscle actuator are fabricated to achieve strong and fast actuation. The hydrogel actuator has shown potential applications in soft robots and artificial muscles.

A novel natural-derived tilapia skin collagen mineralized with hydroxyapatite as a potential bone-grafting scaffold.

Collagen is widely used in medical field because of its excellent biocompatibility and bioactivity. To date, collagen for biomedical use is always derived from bovine or swine. The purpose of this study was to evaluate collagen-based biomaterials from non-mammalian donors for bone repair. Thus, tilapia skin collagen-hydroxyapatite (T-col/HAp) scaffolds were fabricated in three different proportions and then cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide-N-hydroxysuccinimide (EDC-NHS). The scaffolds were evaluated for their microstructure, chemical and physical properties, mechanical strength and degradability. Then the in vitro responses of bone mesenchymal stem cells (BMSCs) to the scaffolds were investigated in terms of cellular proliferation, differentiation, and mineralization. At last, the scaffolds were implanted into rat skull critical defections to investigate the potential of osteogenic activities. As a result, the pore sizes and the porosities of the scaffolds were approximately 106.67-196.67 µm and 81.5%-66.7%. Pure collagen group showed a mechanical strength of 0.065 MPa, and the mechanical strength was significantly enhanced almost 17 times and 32 times in collagen/HAp ratio 1:4 and 1:9 groups. In vitro studies revealed the most prominent and healthy growth of BMSCs in collagen/HAp ratio 1:4 group. All the scaffolds showed certain osteogenic activities and those loaded with small amount of hydroxyapatite showed the strongest bioactivities. The micro-CT showed that the critical bone defect was almost filled with generated bone 6 months after implantation in collagen/HAp ratio 1:4 group. The biomechanics tests further confirmed the highest generated bone strength was in the collagen/HAp ratio 1:4 group. This study indicated aquatic collagen might be a potential alternative for type I collagen from mammals in bone tissue engineering. The combination of collagen and inorganic materials was also important and appropriate inorganic component loading can achieve both osteogenic quality and osteogenic efficiency to a certain extent.

Joint Enhancement in the Electrochemical Reversibility and Cycle Lives for Copper Sulfide for Sodium- and Potassium-Ion Storage via Selenium Substitution.

Transition metal sulfides have received considerable interest as the anodes for sodium-ion (SIBs) and potassium-ion batteries (PIBs) owing to their high theoretical capacity and suitable working potential. However, they suffer from poor electrochemical reversibility and limited cycle lives. Herein, we design and synthesize a Se-substituted CuS material, which demonstrates superior electrochemical properties for both potassium and sodium storage because of the enhanced electronic conductivity, lowered diffusion barrier, and shortened diffusion pathway. The anode delivers a specific capacity of 374 mA h g-1 at a current density of 5 A g-1 in SIBs and 341 mA h g-1 at 2 A g-1 in PIBs and nearly 100% capacity retention over 2000 cycles (SIBs) and 600 cycles (PIBs), respectively. Moreover, a combined measurement including X-ray diffraction, Raman, and transmission electron microscopy reveals an interesting discharge product of Na2S0.8Se0.2, which could accelerate the conversion reaction and enhance the electrochemical reversibility.

Polymorph Engineering for Boosted Volumetric Na-Ion and Li-Ion Storage.

To meet the ever-growing demand for advanced rechargeable batteries with light weight and compact size, much effort has been devoted to improving the volumetric capacity of electrodes. Herein, an effective strategy of polymorph engineering is proposed to boost the volumetric capacity of FeSe. Owing to the inherent metallic electronic conductivity of tetragonal-FeSe, a conductive additive-free electrode (hereafter denoted as CA-free) can be assembled with an enhanced sodium storage volumetric capacity of 1011 mAh cm-3 , significantly higher than semiconducting hexagonal-FeSe. Impressively, the CA-free electrode can achieve an extremely high active material utilization of 96.7 wt% and high initial Coulombic efficiency of 96%, superior to most of the anodes for Na-ion storage. Moreover, the design methodology is branched out using tetragonal FeSe as the cathode for Li-ion batteries. The CA-free tetragonal-FeSe electrode can achieve a high volumetric energy density of 1373 Wh L-1 and power density of 7200 W L-1 , outperforming most metal chalcogenides. Reversible conversion reactions are revealed by in situ XRD for both sodium and lithium systems. The proposed design strategy provides new insight and inspiration to aid in the ongoing quest for better electrode materials.

Co9S8@carbon nanofiber as the high-performance anode for potassium-ion storage.

Thanks to their intrinsic merits of low cost and natural abundance, potassium-ion batteries have drawn intense interest and are regarded as a possible replacement for lithium-ion batteries. The larger radius of potassium, however, provides slow mobility, which normally leads to sluggish diffusion of host materials and eventual expansion of volume, typically resulting in electrode failure. To address these issues, we design and synthesize an effective micro-structure with Co9S8 nanoparticles segregated in carbon fiber utilizing a concise electrospinning process. The anode delivers a high K+ storage capacity of 721 mA h g-1 at 0.1 A g-1 and a remarkable rate performance of 360 mA h g-1 at a high current density of 3 A g-1. A small charge-transfer resistance and a high pseudocapacitive contribution that benefit fast potassium ion migration are indicated by quantitative analysis. The outstanding electrochemical performance can be attributed to the distinct architecture design facilitating high active electrode-electrolyte area and fast kinetics as well as controlled volume expansion.

Magnesium-doped Nanostructured Titanium Surface Modulates Macrophage-mediated Inflammatory Response for Ameliorative Osseointegration.

BACKGROUND: Next generation of coating materials on the surface of implants is designed with a paradigm shift from an inert material to an osteoimmunomodulatory material. Regulating immune response to biomedical implants through influencing the polarization of macrophage has been proven to be an effective strategy. METHODS: Through anodization and hydrothermal treatment, magnesium ion incorporated TiO2 nanotube array (MgN) coating was fabricated on the surface of titanium and it is hypothesized that it has osteoimmunomodulatory properties. To verify this assumption, systematic studies were carried out by in vitro and in vivo experiments. RESULTS: Mg ion release behavior results showed that MgN coating was successfully fabricated on the surface of titanium using anodization and hydrothermal technology. Scanning electron microscopy (SEM) images showed the morphology of the MgN coating on the titanium. The expression of inflammation-related genes (IL-6, IL-1ß, TNF-α) was downregulated in MgN group compared with TiO2 nanotube (NT) and blank Ti groups, but anti-inflammatory genes (IL-10 and IL-1ra) were remarkably upregulated in the MgN group. The in vitro and in vivo results demonstrated that MgN coating influenced macrophage polarization toward the M2 phenotype compared with NT and blank-Ti groups, which enhanced osteogenic differentiation of rat bone mesenchymal stem cells rBMSCs in conditioned media (CM) generated by macrophages. CONCLUSION: MgN coating on the titanium endowed the surface with immune-regulatory features and exerted an advantageous effect on osteogenesis, thereby providing excellent strategies for the surface modification of biomedical implants.

Preparation of textured and transparent BiVO4 photoelectrodes based on Mo-doped BiVO4 nanoparticles for constructing a stand-alone tandem water splitting device.

Crystallographic orientation control is an effective method to improve the photoelectrochemical water splitting efficiency of BiVO4 photoanodes. Herein, textured and transparent Mo-BiVO4 photoanodes are fabricated by spin-coating Mo-doped BiVO4 nanoparticles on FTO. The photoelectrodes exhibit a current density of 4.15 mA cm-2 and 2.50 mA cm-2 for sulfite and water oxidation, respectively. By connecting the photoelectrode with a CsPbBrI2 perovskite solar cell, a stand-alone tandem water splitting device with a current density of 2.13 mA cm-2 and an STH of 2.43% can be achieved.

CBCT Analysis of Changes in Dental Occlusion and Temporomandibular Joints before and after MEAW Orthotherapy in Patients with Nonlow Angle of Skeletal Class III.

This study focus on the changes of the position and morphology of jaw and condyle after MEAW (the multiloop edgewise arch wire) treatment in adults with a nonlow angle (mean angle or high angle SN - MP > 27°) of skeletal class III (mild to moderate skeletal classs III means -5° < ANB < 0°) malocclusions measured by CBCT (cone beam computed tomography). Twenty adult patients (aged 17-26) with a nonlow angle of skeletal class III malocclusions were selected in this study taken orthodontic treatment by MEAW. CBCT was taken before and after the treatment to analyze the changes of the jaw and condyle. After treatment, the angle of L7-MP decreased 12.2°, L6-MP decreased 10.5°, L1-MP decreased 8.8° (P < 0.001 for each) and U1-SN increased (P < 0.05). There was no significant changes between anterior and posterior APDI index and between anterior and posterior spaces of the TMJ (temporomandibular joint) (P > 0.05). The linear ratio of the TMJ was the LR > 12 before treatment, while it was -12 < LR < 12 after treatment; however, there was no statistically significant difference between them (P > 0.05). There was also no significant change in anterior and posterior position and morphology of the condyle within the joint fossa after the treatment by MEAW in this study. MEAW technology in correcting the class III with nonlow angle patients mainly relies on the compensation of distally and posterior mandibular teeth, rather than the mandible and condyle moving backward to establish a neutral occlusal. This study was approved by the institutional ethics committee of the Second Hospital of Tianjin Medical University (No. KYJJ2013002).

Preparation of SiO2@TiO2:Eu3+@TiO2 core double-shell microspheres for photodegradation of polyacrylamide.

Recently, polyacrylamide (PAM) has been widely used in polymer flooding technology to enhance oil recovery and oil production. However, the difficulty in removing hydrolysed PAM (HPAM) from wastewater still seriously blocks the further application of polymer flooding in the oilfields. Herein, we demonstrate the preparation of SiO2@TiO2:Eu3+@TiO2 core double-shell microspheres (STT) through a two-step solvothermal and sol-gel coating strategy. The as-prepared STT exhibits an ideal photocatalytic activity for the photodegradation of HPAM. More importantly, by using STT as the model, the correlation between fluorescence intensity and photocatalytic activity of the photocatalysts is investigated. The results suggest their oppositional relationship. Since many kinds of photocatalysts are utilized in the degradation of organic pollutants, it is believed that our work will not only promote the development of photocatalysis in the field of oil extraction, but also offer a convenient method for evaluating the photocatalytic activity of the photocatalysts.

Green-solvent-processed hybrid solar cells based on donor-acceptor conjugated polyelectrolyte.

In this work, a quaternary ammonium side chain modified conjugated polyelectrolyte PFBTBr, with excellent solubility in nonaromatic and nonhalogenated solvents, was designed and synthesized as the donor material for the green-solvent-processed hybrid solar cells (HSCs). By introducing the donor-acceptor structure, PFBTBr shows a lower lying highest occupied molecular orbital (HOMO) level and a broad absorption from 300 to 700 nm. Incorporating the water soluble CdTe nanocrystals (NCs) as acceptor, the green-solvent-processed HSCs based on conjugated polyelectrolyte and inorganic NCs were fabricated. Through the active layer optimization, a well blended donor/acceptor active layer with continuous electron/hole transport pathway and smoother surface was achieved. As a result, a photovoltaic efficiency of 3.67% was realized. After the further interfacial modification and chloride treatment, the power conversion efficiency of the green-solvent-processed HSCs was improved to 5.03% with the maximum external quantum efficiency value of 87.01% at 400 nm under the AM 1.5 G 100 mW cm-2 illumination.