Effects of sintering additives and sintering methods on the mechanical, antimicrobial and optical properties of Si3N4 bioceramics

Si3N4 bioceramics were fabricated using GPS and SPS method with MgO-RE2O3 (RE = La, Nd, Gd, Ho and Lu) sintering additives. The effect of sintering methods and sintering additives on the grain growth, mechanical, antimicrobial properties and color of Si3N4 bioceramics were studied. Samples sintered with GPS are composed of β-Si3N4 and samples sintered with SPS are composed of α-Si3N4 and β-Si3N4. The growth of β-Si3N4 grains in samples sintered with GPS are more adequate. Samples sintered with GPS exhibit a S. aureus inactivation rate up to 98% and a bright color appearance with a hardness of about 13 GPa and a fracture toughness up to 7.5 MPa m1/2, suitable for dental implants. And samples sintered with SPS exhibit a hardness of about 17 GPa and a fracture toughness about 6 MPa m1/2.

Syntheses of Cannabinoid Metabolites: Ajulemic Acid and HU-210

Cannabinoid metabolites have been reported to be more potent than their parent compounds. Among them, ajulemic acid (AJA) is a side-chain analog of Δ9-THC-11-oic acid, which would be a good template structure for the discovery of more potent analogues. Herein, we optimized the key allylic oxidation step to introduce the C-11 hydroxy group with a high yield. A series of compounds was prepared with this condition applied including HU-210, 11-nor-Δ8-tetrahydrocannabinol (THC)-carboxylic acid and Δ9-THC-carboxylic acid.

Glycogen synthase kinase 3 controls T-cell exhaustion by regulating NFAT activation

Cellular immunity mediated by CD8+ T cells plays an indispensable role in bacterial and viral clearance and cancers. However, persistent antigen stimulation of CD8+ T cells leads to an exhausted or dysfunctional cellular state characterized by the loss of effector function and high expression of inhibitory receptors during chronic viral infection and in tumors. Numerous studies have shown that glycogen synthase kinase 3 (GSK3) controls the function and development of immune cells, but whether GSK3 affects CD8+ T cells is not clearly elucidated. Here, we demonstrate that mice with deletion of Gsk3α and Gsk3β in activated CD8+ T cells (DKO) exhibited decreased CTL differentiation and effector function during acute and chronic viral infection. In addition, DKO mice failed to control tumor growth due to the upregulated expression of inhibitory receptors and augmented T-cell exhaustion in tumor-infiltrating CD8+ T cells. Strikingly, anti-PD-1 immunotherapy substantially restored tumor rejection in DKO mice. Mechanistically, GSK3 regulates T-cell exhaustion by suppressing TCR-induced nuclear import of NFAT, thereby in turn dampening NFAT-mediated exhaustion-related gene expression, including TOX/TOX2 and PD-1. Thus, we uncovered the molecular mechanisms underlying GSK3 regulation of CTL differentiation and T-cell exhaustion in anti-tumor immune responses.

Three nona-2,7-dienoic acid derivatives from saltern derived Micromonospora sp. FXY415

Three new compounds, apocimycin A-C, were identified from a saltern-derived Micromonospora sp. strain FXY415, isolated from Dongshi saltern, Fujian, China. Their planar structures and relative configuration were confirmed mainly by analysis of 1D- and 2D- NMR spectra. Three compounds belong to 4,6,8-trimythyl nona-2,7-dienoic acid derivatives, apocimycin A also has a phenoxazine nucleus. Apocimycin A-C exhibited weak cytotoxic and antimicrobial activities. Our research showed again that microbial communities in extreme environments are a potential resource in looking for new and bioactive led compounds.

Effects of land clearing for agriculture on soil organic carbon stocks in drylands: A meta-analysis

Agricultural activities have been expanding globally with the pressure to provide food security to the earth's growing population. These agricultural activities have profoundly impacted soil organic carbon (SOC) stocks in global drylands. However, the effects of clearing natural ecosystems for cropland (CNEC) on SOC are uncertain. To improve our understanding of carbon emissions and sequestration under different land uses, it is necessary to characterize the response patterns of SOC stocks to different types of CNEC. We conducted a meta-analysis with mixed-effect model based on 873 paired observations of SOC in croplands and adjacent natural ecosystems from 159 individual studies in global drylands. Our results indicate that CNEC significantly (p < .05) affects SOC stocks, resulting from a combination of natural land clearing, cropland management practices (fertilizer application, crop species, cultivation duration) and the significant negative effects of initial SOC stocks. Increases in SOC stocks (in 1 m depth) were found in croplands which previously natural land (deserts and shrublands) had low SOC stocks, and the increases were 278.86% (95% confidence interval, 196.43%-361.29%) and 45.38% (26.53%-62.23%), respectively. In contrast, SOC stocks (in 1 m depth) decreased by 24.11% (18.38%-29.85%) and 10.70% (1.80%-19.59%) in clearing forests and grasslands for cropland, respectively. We also established the general response curves of SOC stocks change to increasing cultivation duration, which is crucial for accurately estimating regional carbon dynamics following CNEC. SOC stocks increased significantly (p < .05) with high long-term fertilizer consumption in cleared grasslands with low initial SOC stocks (about 27.2 Mg ha^-1 ). The results derived from our meta-analysis could be used for refining the estimation of dryland carbon dynamics and developing SOC sequestration strategies to achieve the removal of CO₂ from the atmosphere.

Single atoms (Pt, Ir and Rh) anchored on activated NiCo LDH for alkaline hydrogen evolution reaction

Here, we report the synthesis of activated NiCo LDH to immobilize Pt, Ir and Rh single atoms for hydrogen evolution reaction. The Pt/A-NiCo LDH electrocatalyst exhibits the highest catalytic ability with a low overpotential of 16 mV to achieve a current density of 10 mA cm^-2 and a mass activity about 24.8-fold that of commercial Pt/C. The results suggest that the Pt single atom catalyst can not only accelerate the Volmer steps in alkaline media, but also optimize the hydrogen adsorption process, improving the HER catalytic activity.

Ni-Doped Mo2C Anchored on Graphitized Porous Carbon for Boosting Electrocatalytic N2 Reduction

Facilitating the efficient activation of N₂ molecules and inhibiting the competing hydrogen evolution reaction remain a challenge in the nitrogen reduction reaction (NRR). A heteroatom doping strategy is an effective way to optimize the energy barrier during the NRR process to improve the catalytic efficiency. Herein, we report Ni-doped Mo₂C anchored on graphitized porous conductive carbon for regulating the electronic structure and catalytic properties of electrocatalysts toward NRR. Benefiting from the porous structure and graphitization features of the carbon matrix, more active sites and high electronic conductivity were achieved. Meanwhile, with the doping of Ni atoms, the electronic configuration near the Ni-Mo active sites was optimized and the adsorption of N₂ on them was also promoted due to the increased electron transfer. Moreover, the lowered energy barrier of the NRR process and the suppressed hydrogen adsorption on the active site all resulted in the high catalytic activity and selectivity of the catalyst. Therefore, a high NH₃ yield rate of 46.49 μg h^-1 mg^-1 and a faradic efficiency of 29.05% were achieved. This work not only validates the important role of heteroatom doping on the regulation of NRR catalytic activity but also provides a promising avenue for the green synthesis of NH₃.

Ultrasonication-aided self-assembly strategy toward PTCDA/RGO film cathode for organic K-ion full batteries

A free-standing PTCDA/RGO film was synthesized by ultrasonication-aided self-assembly strategy to alleviate the solubility of PTCDA in organic electrolyte. The PTCDA/RGO-50% film cathode exhibits a high capacity of 135.1 mA...

Microstructure-Dependent K+ Storage in Porous Hard Carbon

Hard carbons (HCs) are emerging as promising anodes for potassium-ion batteries (PIBs) due to overwhelming advantages including cost effectiveness and outstanding physicochemical properties. However, the fundamental K⁺ storage mechanism in HCs and the key structural parameters that determining K⁺ storage behaviors remain unclear and require further exploration. Herein, HC materials with controllable micro/mesopore structures are first synthesized by template-assisted spray pyrolysis technology. Detailed experimental analyses including in situ Raman and in situ electrochemical impedance spectroscopy analysis reveal two different K⁺ storage ways in the porous hard carbon (p-HC), e.g., the adsorption mechanism at high potential region and the intercalation mechanism at low potential region. Both are strongly dependent on the evolution of microstructure and significantly affect the electrochemical performance. Specifically, the adequate micropores act as the active sites for efficient K⁺ storage and ion-buffering reservoir to relieve the volume expansion, ensuring enhanced specific capacity and good structural stability. The abundant mesopores in the porous structure provide conductive pathways for ion diffusion and/or electrolyte infiltration, endowing fast ionic/electronic transport kinetics. All these together contribute to the high energy density of activated carbon//p-HCs potassium ion hybrid capacitors (74.5 Wh kg^-1 , at 184.4 W kg^-1 ).

Enhanced Potassium-Ion Storage of the 3D Carbon Superstructure by Manipulating the Nitrogen-Doped Species and Morphology

Potassium-ion batteries (PIBs) are attractive for grid-scale energy storage due to the abundant potassium resource and high energy density. The key to achieving high-performance and large-scale energy storage technology lies in seeking eco-efficient synthetic processes to the design of suitable anode materials. Herein, a spherical sponge-like carbon superstructure (NCS) assembled by 2D nanosheets is rationally and efficiently designed for K⁺ storage. The optimized NCS electrode exhibits an outstanding rate capability, high reversible specific capacity (250 mAh g^-1 at 200 mA g^-1 after 300 cycles), and promising cycling performance (205 mAh g^-1 at 1000 mA g^-1 after 2000 cycles). The superior performance can be attributed to the unique robust spherical structure and 3D electrical transfer network together with nitrogen-rich nanosheets. Moreover, the regulation of the nitrogen doping types and morphology of NCS-5 is also discussed in detail based on the experiments results and density functional theory calculations. This strategy for manipulating the structure and properties of 3D materials is expected to meet the grand challenges for advanced carbon materials as high-performance PIB anodes in practical applications.

Optimized Kinetics Match and Charge Balance Toward Potassium Ion Hybrid Capacitors with Ultrahigh Energy and Power Densities

Potassium ion hybrid capacitors (PIHCs) are of particular interest benefiting from high energy/power densities. However, challenges lie in the kinetic mismatch between battery-type anode and capacitive-type cathode, as well as the difficulty in achieving optimized charge/mass balance. These significantly sacrifice the electrochemical performance of PIHCs. Here, strategies including charge/mass balance pursuance, electrolyte optimization, and tailored electrode design, are employed, together, to address these challenges. The key parameters determining the energy storage properties of PIHCs are identified. Specifically, i) the good kinetic match between anode and cathode translates into the very small variation of cathode/anode mass ratio at various rates. This sets general rules for the pursuance of charge balance, and to maximize the electrochemical performance of hybrid devices. ii) A potassium bis(fluoroslufonyl)imide (KFSI)-based electrolyte promotes better electrode kinetics and allows for the formation of more stable and intact solid electrolyte interphase layer, with respect to potassium hexafluorophosphate (KPF₆ )-based electrolyte. And iii) hierarchically porous N/O codoped carbon nanosheets (NOCSs) with enlarged interlayer spacing, disordered structure, and abundant pyridinic-N functional groups are advantageous in terms of high electronic/ionic transport dynamics and structural stability. All these together, contribute to the high energy/power density of the activated carbon//NOCSs PIHCs (113.4 Wh kg^-1 , at 17,000 W Kg^-1 ).

MiR-15a-3p suppresses the growth and metastasis of ovarian cancer cell by targeting Twist1

OBJECTIVE

To investigate the roles of miR-15a-3p in ovarian cancer cell growth and metastasis.

PATIENTS AND METHODS

A key role of miR-15a-3p was identified via gene profiling and bioinformatics analysis. The impact of miR-15a-3p on ovarian cancer cell growth, migration and invasion was measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), wound-healing and transwell invasion assays. Bioinformatics and luciferase reporter assays were applied to identify that twist family BHLH transcription factor 1 (Twist1) was the target gene of miR-15a-3p. The miR-15a-3p level and the expression of Twist1 were detected using quantitative Real-time polymerase chain reaction (qRT-PCR) assay. The expressions of N-cadherin and E-cadherin were measured by immunofluorescence staining. Small interfering RNA targeting Twist1 and pCDNA3.1 containing Twist1 were applied to decrease and increase the expression of Twist1, respectively.

RESULTS

miR-15a-3p was markedly down-regulated in ovarian cancer. Exogenous up-regulation of miR-15a-3p inhibited the growth, colony formation, migration and invasion of ovarian cancer cell in vitro. Furthermore, a xenograft model indicated that miR-15a-3p inhibited tumour growth and the metastatic potential of ovarian cancer cell in vivo. We found that Twist1 was the direct target of miR-15a-3p in ovarian cancer and that its expression was negatively correlated with the level of miR-15a-3p in ovarian cancer tissues. Up-regulation of miR-15a-3p rescued the inhibitory impact of miR-15a-3p on ovarian cancer cell growth, migration and invasion. Finally, down-regulation of Twist1 mimicked the suppressive effects of miR-15a-3p on ovarian cancer cell.

CONCLUSIONS

We demonstrated that miR-15a-3p is down-regulated in ovarian cancer. Up-regulation of miR-15a-3p restrains the growth and metastasis of ovarian cancer cell by regulating Twist1.

Synthesis of Ordered Mesoporous Zr-Al Composite Oxides with Excellent Structural and Textural Properties and Extremely High Stability

Ordered mesoporous Zr-Al composite oxide materials (denoted as OMZA-x) with different Zr contents have been synthesized by a solvent evaporation-inducing self-assembly procedure associated with a thermal treatment at 100 °C. A cooperative co-assembly process of amphiphilic triblock copolymer F127 molecules and inorganic hydroxyl species originated from the hydrolysis of Zr and Al precursors was proposed to explain the synthesis of OMZA-x. Compared to ordered mesoporous alumina prepared without introducing Zr species, the resultant OMZA-x exhibited a much more ordered mesostructure combined with a distinct increase in the pore volume and specific surface area. The highly homogenous doping of Zr into the mesopore walls together with the formation of Zr-O-Al bonds can effectively enhance the thermal and hydrothermal stability of OMZA-x. For instance, the ordered mesostructure and excellent textural properties of OMZA-6 prepared with the optimum atomic ratio of Al to Zr of 6 could be well maintained even after a high-temperature treatment at 1000 °C for 1 h or a hydrothermal treatment at 100 °C for 6 h.

Study of miR-26a inhibiting epithelial-mesenchymal transition and invasion of Tu686 cell line through SMAD1

OBJECTIVE

This study aims to investigate the effect of miR-26a on the epithelial-mesenchymal transition (EMT) and invasion of Tu686 cell line through SMAD1.

MATERIALS AND METHODS

Tu686 Squamous cell carcinoma of head and neck (SCCHN) cell strains were divided into the miR-26a group, miR-NC group, co-transfection group and blank control group. Among them, the miR-26a group only transfected miR-26a mimics, the miR-NC group only transfected miR-26a negative control, the co-transfection group transfected miR-26a mimics and pcDNA3.1-SMAD1 plasmid. The qRT-PCR method was used for the detection of the expressions of miR-26a and SMAD1 in each group of cells, transwell assay for the detection of the invasion ability of each group of cells and Western blot for detecting the expression level of SMAD1 and the expressions of EMT-related proteins E-cadherin and N-cadherin.

RESULTS

The relative expression of miR-26a in the miR-26a group was significantly higher than that in the miR-NC group and blank control group, and the relative expression in the co-transfection group was significantly higher than that in the miR-NC and blank control groups. The relative expression of SMAD1 in the miR-26a group was significantly lower than that in the miR-NC and blank control groups, and the relative expression in the co-transfection group was lower than that in the miR-NC and blank control groups, and higher than that in the miR-26a group (all p<0.05). There was no significant difference between the miR-NC group and the blank control group (p>0.05).

CONCLUSIONS

miR-26a may reduce the expression level of SMAD1, affect the expression of EMT-related proteins, inhibit the EMT function of Tu686 cells of squamous cell carcinoma of head and neck, and inhibit the invasion of them.

Evaluation of Pantoea eucalypti FBS135 for pine (Pinus massoniana) growth promotion and its genome analysis

AIMS

Pinus massoniana is one of the most widely distributed forest plants in China. In this study, we isolated a bacterial endophyte (designated FBS135) from apical buds and needles of P. massoniana. Investigations were performed to understand the effects of the strain on pine growth, its genomic features and the functions of the plasmids it carries.

METHODS AND RESULTS

Based on its morphological features and 16S rRNA sequence, strain FBS135 was primarily identified as Pantoea eucalypti. We found that FBS135 not only promoted the growth of P. massoniana seedlings, but also significantly increased the survival rate of pine seedlings. The whole genome of FBS135 was sequenced, which revealed that the bacterium carries one chromosome and four plasmids. Its chromosome is 4 023 751 bp in size and contains dozens of genes involved in plant symbiosis. Curing one of the four plasmids, pPant1, resulted in a decrease in the size of the FBS135 colonies and the loss of the ability to synthesize yellow pigment, indicating that this plasmid may be very important for FBS135.

CONCLUSIONS

Pantoea eucalypti FBS135 has a genomic basis to be implicated in plant-associated lifestyle and was established to have the capability to promote pine growth.

SIGNIFICANCE AND IMPACT OF THE STUDY

To the best of our knowledge, this is the first report that such a bacterial species, P. eucalypti, was isolated from pine trees and evidenced to have pine beneficial activities. Our results elucidate the ecological effects of endophytes on forest plants as well as endophyte-plant interaction mechanisms.

Impact of P inputs on source-sink P dynamics of sediment along an agricultural ditch network

Phosphorus (P) loss from intensive dairy farms is a pressure on water quality in agricultural catchments. At farm scale, P sources can enter in-field drains and open ditches, resulting in transfer along ditch networks and delivery into nearby streams. Open ditches could be a potential location for P mitigation if the right location was identified, depending on P sources entering the ditch and the source-sink dynamics at the sediment-water interface. The objective of this study was to identify the right location along a ditch to mitigate P losses on an intensive dairy farm. High spatial resolution grab samples for water quality, along with sediment and bankside samples, were collected along an open ditch network to characterise the P dynamics within the ditch. Phosphorus inputs to the ditch adversely affected water quality, and a step change in P concentrations (increase in mean dissolved reactive phosphorus (DRP) from 0.054 to 0.228 mg L^-1) midway along the section of the ditch sampled, signalled the influence of a point source entering the ditch. Phosphorus inputs altered sediment P sorption properties as P accumulated along the length of the ditch. Accumulation of bankside and sediment labile extractable P, Mehlich 3 P (M3P) (from 13 to 97 mg kg^-1) resulted in a decrease in P binding energies (k) to < 1 L mg^-1 at downstream points and raised the equilibrium P concentrations (EPC₀) from 0.07 to 4.61 mg L^-1 along the ditch. The increase in EPC₀ was in line with increasing dissolved and total P in water, demonstrating the role of sediment downstream in this ditch as a secondary source of P to water. Implementation of intervention measures are needed to both mitigate P loss and remediate sediment to restore the sink properties. In-ditch measures need to account for a physicochemical lag time before improvements in water quality will be observed.

Synthesis of novel mesoporous sulfated zirconia nanosheets derived from Zr-based metal–organic frameworks

Flower-like mesoporous sulfated zirconia nanosheets (SZNs) were developed by pyrolysis of in situ sulfated Zr-MOFs for the first time.

Tensorial Modulation of Electrokinetic Streaming Potentials on Air and Liquid Filled Surfaces

Textured surfaces, comprised of grooves filled with air, e.g., air-filled surfaces (AFS), or with liquid, e.g., liquid-filled surfaces (LFS), significantly influence fluid flows and the related electrokinetic streaming potential (V_s). Here, electroosmotic mobility related tensorial effects on the V_s were experimentally investigated. A significant modulation of the V_s, as high as 100%, due to transverse pressure gradients, was demonstrated. The study yields insights into understanding geometrical effects in electrolyte flows with implications to the establishment of local electric fields, energy generation, and biological separations.

Hollow-Core-Photonic-Crystal-Fiber-Based Miniaturized Sensor for the Detection of Aggregation-Induced-Emission Molecules

A miniature sensor for detection of aggregation-induced-emission (AIE) molecules is proposed in this work. The sensing head is fabricated by use of hollow-core photonic crystal fiber with a core diameter of about 4.8 μm. The cladding holes are sealed with a fusion splicing technique, and the central hole remains open to allow the filtration of solution with AIE molecules. When the solution is excited by an ultraviolet lamp, the fluorescence is received by a fiber-optic spectrometer. The fluorescence intensity is associated with the concentration of AIE molecules and the infiltrated-core length. In the whole process of the experiments, the output-peak wavelength is stable, which indicates that the existing forms of AIE particles are stable, and the fluorescence reabsorption can be neglected. The experimental results obtained are in accordance with traditional microplate-spectrophotometer methods. The most exciting result is that the amount of sample measured can be as low as 0.36 nL, which allows the detection of AIE molecules at only 0.02 pmol. In addition, the miniature sensor was successfully applied to the detection of an AIE-based bioprobe for evaluating the activity of the dipeptidyl-peptidase 4 (DPP-4) inhibitor sitagliptin with an IC₅₀ of 59.80 ± 3.06 nM. The advantages of small device size and nanoliter-scale sample volumes suggest that the proposed sensor is promising for many biosensing applications.

Enhanced voltage generation through electrolyte flow on liquid-filled surfaces

The generation of electrical voltage through the flow of an electrolyte over a charged surface may be used for energy transduction. Here, we show that enhanced electrical potential differences (i.e., streaming potential) may be obtained through the flow of salt water on liquid-filled surfaces that are infiltrated with a lower dielectric constant liquid, such as oil, to harness electrolyte slip and associated surface charge. A record-high figure of merit, in terms of the voltage generated per unit applied pressure, of 0.043 mV Pa⁻¹ is obtained through the use of the liquid-filled surfaces. In comparison with air-filled surfaces, the figure of merit associated with the liquid-filled surface increases by a factor of 1.4. These results lay the basis for innovative surface charge engineering methodology for the study of electrokinetic phenomena at the microscale, with possible application in new electrical power sources.

Superhydrophobic surfaces are expected to increase streaming potential, but are hindered by the presence of air. Here the authors enhance streaming potential by flowing high-dielectric salt water over liquid-filled surfaces infiltrated with low-dielectric liquid, harnessing electric slip and surface charge.

Enhanced Solar Thermal Evaporation of Ethanol-Water Mixtures, through the Use of Porous Media

A significant enhancement of solar irradiation induced evaporation of water, and ethanol-water mixtures, through the use of carbon foam based porous media, is demonstrated. A relationship between the consequent rate of mass loss, with respect to the equilibrium vapor pressure, dynamic viscosity, surface tension, and density, was developed to explain experimental observations. The evaporative heat loss was parametrized through two convective heat transfer coefficients-one related to the surface and another related to the vapor external to the surface. The work promotes a better understanding of thermal processes in binary liquid mixtures with applications ranging from phase separation to distillation and desalination.

Compact-Nanobox Engineering of Transition Metal Oxides with Enhanced Initial Coulombic Efficiency for Lithium-Ion Battery Anodes

A novel strategy is proposed to construct a compact-nanobox (CNB) structure composed of irregular nanograins (average diameter ≈ 10 nm), aiming to confine the electrode-electrolyte contact area and enhance initial Coulombic efficiency (ICE) of transition metal oxide (TMO) anodes. To demonstrate the validity of this attempt, CoO-CNB is taken as an example which is synthesized via a carbothermic reduction method. Benefiting from the compact configuration, electrolyte can only contact the outer surface of the nanobox, keeping the inner CoO nanograins untouched. Therefore, the solid electrolyte interphase (SEI) formation is reduced. Furthermore, the internal cavity leaves enough room for volume variation upon lithiation and delithiation, resulting in superior mechanical stability of the CNB structure and less generation of fresh SEI. Consequently, the SEI remains stable and spatially confined without degradation, and hence, the CoO-CNB electrode delivers an enhanced ICE of 82.2%, which is among the highest values reported for TMO-based anodes in lithium-ion batteries. In addition, the CoO-CNB electrode also demonstrates excellent cyclability with a reversible capacity of 811.6 mA h g^-1 (90.4% capacity retention after 100 cycles). These findings open up a new way to design high-ICE electrodes and boost the practical application of TMO anodes.