Mineral Phase Reconfiguration Enables the High Enzyme-like Activity of Vermiculite for Antibacterial Application.

Phyllosilicates-based nanomaterials, particularly iron-rich vermiculite (VMT), have wide applications in biomedicine. However, the lack of effective methods to activate the functional layer covered by the external inert layer limits their future applications. Herein, we report a mineral phase reconfiguration strategy to prepare novel nanozymes by a molten salt method. The peroxidase-like activity of the VMT reconfiguration nanozyme is 10 times that of VMT, due to the electronic structure change of iron in VMT. Density-functional theory calculations confirmed that the upward shifted d-band center of the VMT reconfiguration nanozyme promoted the adsorption of H2O2 on the active iron sites and significantly elongated the O-O bond lengths. The reconfiguration nanozyme exhibited nearly 100% antibacterial activity toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), much higher than that of VMT (E. coli 10%, S. aureus 21%). This work provides new insights for the rational design of efficient bioactive phyllosilicates-based nanozyme.

Optimizing germination: comparative assessment of various growth media on dragon fruit germination and early growth.

Dragon fruit (Selenicereus undatus), known for its captivating appearance and remarkable nutritional profile, has garnered considerable attention in recent years. Despite its popularity, there's a dearth of research on optimal conditions for seed germination and early growth stages such as seedling shoot length, which are crucial for optimal crop yield. This study aims to bridge this gap by evaluating various growing media's performance on dragon fruit germination and early growth stages. Dragon fruit seeds were obtained from local markets in Pakistan and evaluated in five different growing media: cocopeat, peat moss, sand, vermiculite, and compost. Germination parameters were observed for 45 days, including seed germination percentage, mean germination time, and mean daily germination percentage, among others while early growth was monitored for 240 days. Statistical analysis was conducted using ANOVA and Tukey's HSD test. Significant differences were found among the growing media regarding germination percentage, mean germination time, and mean daily germination. Vermiculite exhibited the highest germination rate (93.33%), while compost showed the least (70%). Peat moss and sand media facilitated rapid germination, while compost showed slower rates. Stem length was significantly influenced by the growth media, with compost supporting the longest stems. Vermiculite emerged as the most effective medium for dragon fruit seed germination, while compost showed slower but steady growth. These findings provide valuable insights for optimizing dragon fruit cultivation, aiding commercial growers and enthusiasts in achieving higher yields and quality. Further research could explore additional factors influencing dragon fruit growth and development.

Non-Covalent Interaction Enhancement on Active/Interfacial Layers via Two-Dimensional Vermiculite Doping for Efficient Organic Solar Cells.

Interface modification plays an important role in improving the power conversion efficiency (PCE) of organic solar cells (OSCs). However, the low non-covalent interaction between the cathode interface layer (CIL) and nonfullerene acceptor (NFA) directly affects the charge collection of OSCs. Here, the non-covalent interaction between the CIL and NFA is enhanced by introducing the 2D vermiculite (VML) in the poly(9,9-bis(3'-(N,N-dimethyl)-Nethylammonium-propyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide (PFN-Br) interface layer to form an efficient electron transport channel. As a result, the electron extraction efficiency from the active layer to the CIL is increased, and the PCE of OSCs based on PBDB-T:ITIC is boosted from 10.87% to 12.89%. In addition, the strategy of CIL doping VML is proven to be universal in different CIL materials, for which the PCE is boosted from 10.21% to 11.57% for OSCs based on PDINN and from 9.82% to 11.27% for OSCs based on PNDIT-F3N. The results provide a viable option for designing efficient CIL for high-performance non-fullerene OSCs, which may promote the commercialization of OSCs.

VMT/ACP/Dextran composite nanosheets against dental caries through promoting mineralization of dentin tubules, pH buffering, and antibacterial.

Dental caries is a worldwide public healthcare concern, and is closely related to the acidic environment that caused by bacterial decomposition of food. In this study, a two-step ion exchange liquid-phase stripping method was applied to strip out vermiculite (VMT) nanosheets, then amorphous calcium phosphate (ACP) and dextran were inserted between the VMT nanosheets interlayer to obtain a composite two-dimension nanosheets (VMT/ACP/Dextran). VMT/ACP/Dextran composite nanosheets exhibited excellent biocompatibility and could provide exogenous Ca2+and PO43- from ACP, provide SiO44-, Mg2+, Fe2+ and obtain buffering pH and antibacterial properties from VMT, as well as improve suspension stability and targeting Streptococcus mutans through glucan. The in vitro study showed that the composite materials could promote the mineralization and sealing of dentin tubules by releasing active ions, buffer pH 4.5 (a value close to the pH in the dental plaque environment) to pH 6.6-7.1 (values close to the pH in human saliva) through ion exchange, and exert antibacterial effects by targeting Streptococcus mutans and exerting oxidase like and peroxidase like activities to produce reactive oxygen species (ROS). The in vivo animal study showed that daily cleaning teeth using VMT/ACP/Dextran composite nanosheets could effectively reduce the incidence rate and severity of dental caries in rats. Taking together, the developed VMT/ACP/Dextran composite nanosheets, which integrated the excellent properties of VMT, ACP and dextran, can effectively prevent dental caries through a combination of factors such as buffering acids, antibacterial properties, and promoting calcification, and may be used as an active ingredient for daily oral hygiene or filling materials to prevent and treat dental caries.

Anisotropic relaxation of nuclear spins dipolar energy of water molecules in two-dimensional nanopores - A single crystal NMR study.

Energy transfer from Zeeman to dipolar order discovered by Jeener et al. is usually observed in solids with a strong dipole-dipole interaction of nuclear spins. It is not observed in liquids, where fast molecular motion completely averages this interaction. The intermediate case, when the dipole-dipole interaction of nuclear spins is only partially averaged, has been poorly studied. We report on the first measurement of an angular-dependent proton spin relaxation of a dipolar reservoir in mobile water molecules confined in the interlayer pores of a vermiculite single crystal. In this layered crystal, the intramolecular dipole-dipole interactions of nuclear spins are only partially averaged due to the restricted anisotropic molecular motion in nanopores. We show that this allows the formation of dipolar echo. We measured the spin-lattice relaxation times of the dipolar order T1D at different angles between the normal to the crystal surface and the applied magnetic field and obtained a distinct angular dependence of T1D. The minimum relaxation rate R1D was found around the magic angle of 54.74°.

Stabilization of heavy metals in solid waste and sludge pyrolysis by intercalation-exfoliation modified vermiculite.

Increasing amounts of solid waste and sludge have created many environmental management problems. Pyrolysis can effectively reduce the volume of solid waste and sludge, but there is still the problem of heavy metal contamination, which limits the application of pyrolysis in environmental management. The intercalated-exfoliated modified vermiculite (IEMV) by intercalators of sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide and octadecyltrimethylammonium bromide were used to control the release of Cd, Cr, Cu, Zn and Pb during pyrolysis process of sludge or solid waste. The retention of heavy metals in sludge was generally better than that in solid waste. The IEMV by octadecyltrimethylammonium bromide as the intercalator calcined 800 °C (STAB-800) was the best additive for heavy metal retention, and the retention of Cr, Cu and Zn was significantly better than that of Pb and Cd. Cr, Cu, Zn and Pb were at low risk, while Cd had considerable risk under certain circumstances. New models were proposed to comprehensively evaluate the results of the risk and forms of heavy metals, and the increasing temperature was beneficial in reducing the hazards of heavy metals by the addition of STAB-800. The reaction mechanism of heavy metals with vermiculite was revealed by simulation of reaction sites, Fukui Function and Frontier Molecular Orbital. Thermal activation-intercalated-exfoliated modified vermiculite (T-IEMV) is more reactive and had more active sites for heavy metals. Mg atoms and outermost O atoms are the main atoms for T-IEMV to react with heavy metals. The Cr, Cu and Zn have better adsorption capacity by T-IEMV than Pb and Cd. This study provides a new insight into managing solid waste and sludge and controlling heavy metal environmental pollution.

Preparation and Lithium-Ion Capacitance Performance of Nitrogen and Sulfur Co-Doped Carbon Nanosheets with Limited Space via the Vermiculite Template Method.

Nitrogen and sulfur co-doped graphene-like carbon nanosheets (CNSs) with a two-dimensional structure are prepared by using methylene blue as a carbon source and expanded vermiculite as a template. After static negative pressure adsorption, high-temperature calcination, and etching in a vacuum oven, they are embedded in the limited space of the vermiculite template. The addition of an appropriate number of mixed elements can improve the performance of a battery. Via scanning electron microscopy, it is found that the prepared nitrogen-sulfur-co-doped carbon nanosheets exhibit a thin yarn shape. The XPS results show that there are four elements of C, N, O, and S in the carbon materials (CNS-600, CNS-700, CNS-800, CNS-900) prepared at different temperatures, and the N atom content shows a gradually decreasing trend. It is mainly doped into a graphene-like network in four ways (graphite nitrogen, pyridine nitrogen, pyrrole nitrogen, and pyridine nitrogen oxide), while the S element shows an increasing trend, mainly in the form of thiophene S and sulfur, which is covalently linked to oxygen. The results show that CNS-700 has a discharge-specific capacity of 460 mAh/g at a current density of 0.1 A/g, and it can still maintain a specific capacity of 200 mAh/g at a current density of 2 A/g. The assembled lithium-ion capacitor has excellent energy density and power density, with a maximum power density of 20,000 W/kg.

Hydrogen Production by Steam Reforming of Ethanol and Dry Reforming of Methane with CO2 on Ni/Vermiculite: Stability Improvement via Acid or Base Treatment of the Support.

In this study, vermiculite was explored as a support material for nickel catalysts in two key processes in syngas production: dry reforming of methane with CO2 and steam reforming of ethanol. The vermiculite underwent acid or base treatment, followed by the preparation of Ni catalysts through incipient wetness impregnation. Characterization was conducted using various techniques, including X-ray diffraction (XRD), SEM-EDS, FTIR, and temperature-programmed reduction (H2-TPR). TG-TD analyses were performed to assess the formation of carbon deposits on spent catalysts. The Ni-based catalysts were used in reaction tests without a reduction pre-treatment. Initially, raw vermiculite-supported nickel showed limited catalytic activity in the dry reforming of methane. After acid (Ni/VTA) or base (Ni/VTB) treatment, vermiculite proved to be an effective support for nickel catalysts that displayed outstanding performance, achieving high methane conversion and hydrogen yield. The acidic treatment improved the reduction of nickel species and reduced carbon deposition, outperforming the Ni over alkali treated support. The prepared catalysts were also evaluated in ethanol steam reforming under various conditions including temperature, water/ethanol ratio, and space velocity, with acid-treated catalysts confirming the best performance.

Superhigh and Robust Ion Selectivity in Membranes Assembled with Monolayer Clay Nanosheets.

It is crucial to control the ion transport in membranes for various technological applications such as energy storage and conversion. The emerging functional two-dimensional (2D) nanosheets such as graphene oxide and MXenes show great potential for constructing ordered nanochannels, but the assembled membranes suffer from low ion selectivity and stability. Here a class of robust charge-selective membranes with superhigh cation/anion selectivity, which are assembled with monolayer nanosheets of cationic/anionic clays that inherently have permanent and uniform charges on each layer is reported. The transport number of cations/anions of cationic vermiculite nanosheet membranes (VNMs)/anionic Co-Al layered double hydroxide (CoAl-LDH) nanosheet membranes is over 0.90 in different NaCl concentration gradients, outperforming all the reported ion-selective membranes. Importantly, this excellent ion selectivity can persist at high-concentration salt solutions, under acidic and alkaline conditions, and for a wide range of ions of different sizes and charges. By coupling a pair of cation-selective vermiculite membrane and anion-selective CoAl-LDH membrane, a reverse electrodialysis device which shows an output power density of 0.7 W m-2 and energy conversion efficiency of 45.5% is constructed. This work provides a new strategy to rationally design high-performance ion-selective membranes by using 2D nanosheets with inherent surface charges for controllable ion-transport applications.

Effect of organic/inorganic composites as soil amendments on the biomass productivity and root architecture of spring wheat and rapeseed.

Organic and inorganic soil amendments are used to increase crop yields and fertilizer efficiency, as well as to improve the physical and biological properties of soil, increase carbon sequestration, and restore contaminated and saline soils. The present study aimed to evaluate the effect of various zeolite composites mixed with either lignite or leonardite on the biomass production of spring wheat and rapeseed and their root morphology. A pot experiment involved the application of the following treatments: zeolite-carbon, zeolite-vermiculite composites, both mixed with lignite or leonardite, and a control treatment with no amendments. Inorganic composites were applied in a dose of 3% and 6%. The study also included an analysis of the root morphometric parameters and aboveground biomass of spring wheat and rapeseed. The lowest productivity was observed when both crops were not enriched with fertilizers or other amendments, 24.92 g per pot and 29.83 g per pot for spring wheat and rapeseed, respectively. The application of mineral fertilizers in combination with zeolite-carbon composite gave the highest aboveground biomass of spring wheat, 110.11 g per pot. Both zeolite-carbon and zeolite-vermiculite composites modified the morphological parameters of roots, with the control treatment showing the lowest root length and dry matter. Although mineral fertilization was found to have a positive impact root development in relation to untreated control, the treatment amended with zeolite-carbon composite and leonardite exhibited the highest root length and biomass of spring wheat. No other soil amendments improved the properties of rapeseed roots.

The Expanded Vermiculite Was Quickly Prepared by the Catalytic Action of Manganese Dioxide on Hydrogen Peroxide and Its Adsorption Properties to Cd.

The structure and activity of vermiculite can be maintained by expanding vermiculite (Vrm) with hydrogen peroxide. However, it is time-consuming. In past studies, little attention has been paid to the catalytic properties of manganese dioxide on hydrogen peroxide to improve the swelling efficiency of vermiculite. In this experiment, this catalytic effect was utilized to swell Vrm in a short time. The samples were then used to adsorb Cd from the solution. Through a series of characterization tests. The results showed that the exothermic rate was 1960.42-2089.164 J/min and the total exothermic heat was 39,208.4-41,783.28 J when expanding 10 gVrm, which could have a good expansion effect. The expansion was completed in about 40 min. Compared with Vrm, the adsorption of Cd is enhanced by about 30%. It is consistent with the proposed secondary kinetic adsorption model. This study provides a new perspective and theoretical guidance for improving the efficiency of Vrm stripping by hydrogen peroxide. A kind of expanded Vrm with better Cd adsorption efficiency was also prepared.

Investigation on Long-Term Stability of Vermiculite Seals for Reversible Solid Oxide Cell.

A reversible solid oxide cell (RSOC) integrating solid oxide fuel (SOFC) and a solid oxide electrolysis cell (SOEC) usually utilizes compressive seals. In this work, the vermiculite seals of various thickness and compressive load during thermal cycles and long-term operation were investigated. The leakage rates of seals were gradually increased with increasing thickness and input gas pressure. The thinner seals had good sealing performance. The compressive load was carried out at thinner seals, the possible holes were squeezed, and finally the leakage rates were lower. With a fixed input gas pressure of 1 psi, 2 psi, and 3 psi, the leakage rates of 0.50 mm vermiculite remained at around 0.009 sccm/cm, 0.017 sccm/cm and 0.028 sccm/cm during twenty thermal cycles, while the leakage rates remained at around 0.011 sccm/cm for about 240 h. Simultaneously, elemental diffusions between seals and components were limited, implying good compatibility. Furthermore, the open circuit voltage (OCV) remained at around 1.04 V during 17 thermal cycles, which is close to Nernst potentials. The stack performance confirmed that the vermiculite seals can meet the structural support and sealing requirements. Therefore, the vermiculite shows good promise for application in stacks during thermal cycles and long-term operation.

Two-dimensional nanovermiculite and polycaprolactone electrospun fibers composite scaffolds promoting diabetic wound healing.

BACKGROUND: Promoting diabetic wound healing is still a challenge, and angiogenesis is believed to be essential for diabetic wound healing. Vermiculite is a natural clay material that is very easy to obtain and exhibits excellent properties of releasing bioactive ions, buffering pH, adsorption, and heat insulation. However, there are still many unsolved difficulties in obtaining two-dimensional vermiculite and using it in the biomedical field in a suitable form. RESULTS: In this study, we present a versatile organic-inorganic composite scaffold, which was constructed by embedding two-dimensional vermiculite nanosheets in polycaprolactone electrospun fibers, for enhancing angiogenesis through activation of the HIF-1α signaling pathway and promoting diabetic wound healing both in vitro and in vivo. CONCLUSIONS: Together, the rational-designed polycaprolactone electrospun fibers-based composite scaffolds integrated with two-dimensional vermiculite nanosheets could significantly improve neo-vascularization, re-epithelialization, and collagen formation in the diabetic wound bed, thus promoting diabetic wound healing. This study provides a new strategy for constructing bioactive materials for highly efficient diabetic wound healing.

Case-fatality study of workers and residents with radiographic asbestos disease in Libby, Montana.

BACKGROUND: Vermiculite ore from Libby, Montana contains on average 24% of a mixture of toxic and carcinogenic amphibole asbestiform fibers. These comprise primarily winchite (84%), with smaller quantities of richterite (11%) and tremolite (6%), which are together referred to as Libby amphibole (LA). METHODS: A total of 1883 individuals who were occupationally and/or environmentally exposed to LA and were diagnosed with asbestos-related pleuropulmonary disease (ARPPD) following participation in communitywide screening programs supported by the Agency for Toxic Substances and Disease Registry (ATSDR) and followed up at the Center for Asbestos Related Disease (CARD) between 2000 and 2010. There were 203 deaths of patients with sufficient records and radiographs. Best clinical and radiologic evidence was used to determine the cause of death, which was compared with death certificates. RESULTS: Asbestos-related mortality was 55% (n = 112) in this series of 203 patients. Of the 203 deaths, 34 (17%) were from asbestos-related malignancy, 75 (37%) were from parenchymal asbestosis, often with pleural fibrosis, and 3 (1.5%) were from respiratory failure secondary to pleural thickening. CONCLUSIONS: Asbestos is the leading cause of mortality following both occupational and nonoccupational exposure to LA in those with asbestos-related disease.

Strategy for enhancing Cr(VI)-contaminated soil remediation and safe utilization by microbial-humic acid-vermiculite-alginate immobilized biocomposite.

Bioreduction is an efficient approach to in-situ remediate Cr(VI)-contaminated soil, but further strengthening methods are still urgently needed. Herein, a novel immobilized biocomposite (B-HA-VE-SA) was successfully synthesized by embedding a efficient strain Bacillus sp. CRB-7 with humic acid (HA) combined vermiculite (VE) and sodium alginate (SA). The performance and enhancement mechanism of the immobilized biocomposite on remediating Cr(VI)-contaminated soil were also investigated by analyzing the whole-genome of CRB-7, Cr(VI) detoxification, soil microecological regulation, and subsequent crop growth response. Genomic annotation demonstrated that CRB-7 contains multiple genes contributed to Cr(VI) tolerance, Cr(VI) reduction and other metals resistance. Results showed that embedded CRB-7 biocomposites exhibited more effective reduction of Cr(VI) in soil compared with control and free CRB-7 treatment, especially B-HA-VE-SA achieved the highest Cr(VI) removal efficiency (96.18%) and the residual Cr proportion (49.04%) via multiple mechanisms including carrier effects, nutrient sustained-release, and electron-shuttle effect enhanced the bioremediation process. Furthermore, the synergies of CRB-7 and immobilizers (HA, VE and SA) significantly improved soil microecology (soil enzyme activities, microbial quantity and diversity), and engendered the evolution of microbial community composition and functional pathways. Consequently, pot experiments (Brassica napus L.) verified the plant-growth-promoting (12.00-18.00% and 43.82-69.00% higher in emergence rate and biomass) and Cr-accumulation-reducing effects (19.47-91.09% and 29.11-89.80% lower in root and aerial parts) of free and immobilized CRB-7. Taken together, these findings highlighted the superiority of B-HA-VE-SA in simultaneous remediation, microecological improvement and safe utilization of Cr(VI)-contaminated soil.

Acid Leaching Vermiculite: A Multi-Functional Solid Catalyst with a Strongly Electrostatic Field and Brönsted Acid for Depolymerization of Cellulose in Water.

Vermiculite is a natural mineral. In this study, vermiculite and acid-activated vermiculite was used as a solid acid catalyst for the hydrolysis of cellulose in water. The catalysts were characterized by XRD, FT-IR, and BET. The effects of time, temperature, mass ratio and water amount on the reaction were investigated in the batch reactor. The results showed that the highest total reducing sugars (TRS) yield of 40.1% could be obtained on the vermiculite activated by 35 (wt)% H2SO4 with the mass ratio of catalyst to cellulose of 0.18 and water to cellulose of 16 at 478 K for 3.5 h. The acid-activated vermiculite was a stable catalyst through calcination at 628 K and the yield of TRS decreased to 36.2% after three times reuse. The results showed that the crystal structure of vermiculite was destroyed and the surface -OH groups increased after the acid treatment. However, the synergistic effect of a strongly electrostatic polarization and Brönsted acid was responsible for the efficient conversion of cellulose. The mechanism of cellulose hydrolysis on the acid-activated vermiculite was suggested. This work provides a promising strategy to design an efficient solid catalyst for the cellulose hydrolysis, and expands the use of vermiculite in a new field.

Effect of moisture-controlled packaging treatment with acid-modified expanded vermiculite-calcium chloride on the quality of fresh mushrooms (Agaricus bisporus) during low-temperature storage.

BACKGROUND: Fresh mushrooms (Agaricus bisporus) are highly perishable and easily lose quality during storage. The packaging system can retard the deterioration of fresh mushrooms. However, water vapor transmission rates of commodity plastic films are lower than the transpiration rate of mushrooms, resulting in increased moisture condensation in the package and perishability of mushrooms due to microbial growth. A possible solution for controlling the humidity level in the package is to use a hygroscopic material. Acid leaching can improve the chemical and physical properties of expanded vermiculite (EV). The aim of this study was to develop a novel hygroscopic agent from acidified expanded vermiculite (AEV) and calcium chloride (CaCl2 ) that has a high moisture absorption capacity and maintains a powdered form in the packaging system for fresh mushrooms. RESULTS: Our findings revealed that leaching EV with hydrochloric acid increased porosity and hydrophilicity. The combination of AEV:CaCl2 at 6:4 (w/w, AEV/CS40) showed the highest moisture adsorption capacity at 1.724 ± 0.03 g water per gram of material. Then, 1.55 g of AEV/CS40 was applied to the mushroom packaging and stored at 4 °C. The results indicated that AEV/CS40 could delay mushroom deterioration in terms of color change, firmness, pH, total soluble solids, and microbial growth. CONCLUSION: The study findings indicate that the alternative solid hygroscopic material obtained by combining AEV with CaCl2 has potential for use as a hygroscopic material for preserving the quality of white button mushrooms. © 2021 Society of Chemical Industry.

Effects of vermiculite on the growth process of submerged macrophyte Vallisneria spiralis and sediment microecological environment.

Ecological restoration is one of the hot technologies for the reconstruction of eutrophic lake ecosystems in which the restoration and propagation of submerged plants is the key and difficult step. In this paper, the effect of vermiculite on the growth process of Vallisneria spiralis and sediment microenvironment were investigated, aiming to provide a theoretical basis for the application of vermiculite in aquatic ecological restoration. Results of growth indexes demonstrated that 5% and 10% vermiculite treatment groups statistically promote the growth of Vallisneria spiralis compared to the control. Meanwhile, the results of ecophysiological indexes showed that photosynthetic pigment, soluble sugar content, superoxide dismutase (SOD), and catalase (CAT) activity of 5% and 10% group were increased compared with the control while the malondialdehyde (MDA) content exhibited the opposite result (p < 0.05), which illustrated that vermiculite can improve the resistance of plants and delay the aging process of Vallisneria spiralis. In addition, result of PCA (Principal Component Analysis) demonstrated 5% and 10% group has improved the sediment physical conditions and create more ecological niche for microorganisms directly, and then promoted the growth of plants. The dissolution results showed that vermiculite can dissolve the constant and trace elements needed for plant growth. Furthermore, the addition of vermiculite increased the diversity of microorganisms in the sediments, and promoted the increase of plant growth-promoting bacteria and phosphorus-degrading bacteria. This study could provide a technique reference for the further application of vermiculite in the field of ecological restoration.

Preparing Two-Dimensional Ordered Li0.33 La0.557 TiO3 Crystal in Interlayer Channel of Thin Laminar Inorganic Solid-State Electrolyte towards Ultrafast Li+ Transfer.

Inorganic superionic conductor holds great promise for high-performance all-solid-state lithium batteries. However, the ionic conductivity of traditional inorganic solid electrolytes (ISEs) is always unsatisfactory owing to the grain boundary resistance and large thickness. Here, a 13 µm-thick laminar framework with ≈1.3 nm interlayer channels is fabricated by self-assembling rigid, hydrophilic vermiculite (Vr) nanosheets. Then, Li0.33 La0.557 TiO3 (LLTO) precursors are impregnated in interlayer channels and afterwards in situ sintered to large-size, oriented, and defect-free LLTO crystal. We demonstrate that the confinement effect permits ordered arrangement of LLTO crystal along the c-axis (the fastest Li+ transfer direction), permitting the resultant 15 µm-thick Vr-LLTO electrolyte an ionic conductivity of 8.22×10-5  S cm-1 and conductance of 87.2 mS at 30 °C. These values are several times' higher than that of traditional LLTO-based electrolytes. Moreover, Vr-LLTO electrolyte has a compressive modulus of 1.24 GPa. Excellent cycling performance is demonstrated with all-solid-state Li/LiFePO4 battery.

The role of JrPPOs in the browning of walnut explants.

BACKGROUND: Tissue culture is an effective method for the rapid breeding of seedlings and improving production efficiency, but explant browning is a key limiting factor of walnut tissue culture. Specifically, the polymerization of PPO-derived quinones that cause explant browning of walnut is not well understood. This study investigated explants of 'Zanmei' walnut shoot apices cultured in agar (A) or vermiculite (V) media, and the survival percentage, changes in phenolic content, POD and PPO activity, and JrPPO expression in explants were studied to determine the role of PPO in the browning of walnut explants. RESULTS: The results showed that the V media greatly reduced the death rate of explants, and 89.9 and 38.7% of the explants cultured in V media and A media survived, respectively. Compared with that of explants at 0 h, the PPO of explants cultured in A was highly active throughout the culture, but activity in those cultured in V remained low. The phenolic level of explants cultured in A increased significantly at 72 h but subsequently declined, and the content in the explants cultured in V increased to a high level only at 144 h. The POD in explants cultured in V showed high activity that did not cause browning. Gene expression assays showed that the expression of JrPPO1 was downregulated in explants cultured in both A and V. However, the expression of JrPPO2 was upregulated in explants cultured in A throughout the culture and upregulated in V at 144 h. JrPPO expression analyses in different tissues showed that JrPPO1 was highly expressed in stems, young leaves, mature leaves, catkins, pistils, and hulls, and JrPPO2 was highly expressed in mature leaves and pistils. Moreover, browning assays showed that both explants in A and leaf tissue exhibited high JrPPO2 activity. CONCLUSION: The rapid increase in phenolic content caused the browning and death of explants. V media delayed the rapid accumulation of phenolic compounds in walnut explants in the short term, which significantly decreased explants mortality. The results suggest that JrPPO2 plays a key role in the oxidation of phenols in explants after branch injury.