Oxygen Vacancies Boosted Proton Intercalation Kinetics for Aqueous Aluminum-Manganese Batteries.

Aluminum-ion batteries have garnered an extensive amount of attention due to their superior electrochemical performance, low cost, and high safety. To address the limitation of battery performance, exploring new cathode materials and understanding the reaction mechanism for these batteries are of great significance. Among numerous candidates, multiple structures and valence states make manganese-based oxides the best choice for aqueous aluminum-ion batteries (AAIBs). In this work, a new cathode consists of γ-MnO2 with abundant oxygen vacancies. As a result, the electrode shows a high discharge capacity of 481.9 mAh g-1 at 0.2 A g-1 and a sustained reversible capacity of 128.6 mAh g-1 after 200 cycles at 0.4 A g-1. In particular, through density functional theory calculation and experimental comparison, the role of oxygen vacancies in accelerating the reaction kinetics of H+ has been verified. This study provides insights into the application of manganese dioxide materials in aqueous AAIBs.

DSSS Signal Detection Based on CNN.

With the wide application of direct sequence spread spectrum (DSSS) signals, the comprehensive performance of DSSS communication systems has been continuously improved, making the electronic reconnaissance link in communication countermeasures more difficult. Electronic reconnaissance technology, as the fundamental means of modern electronic warfare, mainly includes signal detection, recognition, and parameter estimation. At present, research on DSSS detection algorithms is mostly based on the correlation characteristics of DSSS signals, and autocorrelation algorithm is the most mature and widely used method in practical engineering. With the continuous development of deep learning, deep-learning-based methods have gradually been introduced to replace traditional algorithms in the field of signal processing. This paper proposes a spread spectrum signal detection method based on convolutional neural network (CNN). Through experimental analysis, the detection performance of the CNN model proposed in this paper on DSSS signals in various situations has been compared and analyzed with traditional autocorrelation detection methods for different signal-to-noise ratios. The experiments verified the estimation performance of the model in this paper under different signal-to-noise ratios, different spreading code lengths, different spreading code types, and different modulation methods and compared it with the autocorrelation detection algorithm. It was found that the detection performance of the model in this paper was higher than that of the autocorrelation detection method, and the overall performance was improved by 4 dB.

Period Estimation of Spread Spectrum Codes Based on ResNet.

In order to more effectively monitor and interfere with enemy signals, it is particularly important to accurately and efficiently identify the intercepted signals and estimate their parameters in the increasingly complex electromagnetic environment. Therefore, in non-cooperative situations, it is of great practical significance to study how to accurately detect direct sequence spread spectrum (DSSS) signals in real time and estimate their parameters. The traditional time-delay correlation algorithm encounters the challenges such as peak energy leakage and false peak interference. As an alternative, this paper introduces a Pseudo-Noise (PN) code period estimation method utilizing a one-dimensional (1D) convolutional neural network based on the residual network (CNN-ResNet). This method transforms the problem of spread spectrum code period estimation into a multi-classification problem of spread spectrum code length estimation. Firstly, the In-phase/Quadrature(I/Q) two-way of the received DSSS signals is directly input into the CNN-ResNet model, which will automatically learn the characteristics of the DSSS signal with different PN code lengths and then estimate the PN code length. Simulation experiments are conducted using a data set with DSSS signals ranging from -20 to 10 dB in terms of signal-to-noise ratios (SNRs). Upon training and verifying the model using BPSK modulation, it is then put to the test with QPSK-modulated signals, and the estimation performance was analyzed through metrics such as loss function, accuracy rate, recall rate, and confusion matrix. The results demonstrate that the 1D CNN-ResNet proposed in this paper is capable of effectively estimating the PN code period of the non-cooperative DSSS signal, exhibiting robust generalization abilities.

Enhanced anti-microbial activity and osseointegration of Ta/Cu co-implanted polyetheretherketone.

Polyetheretherketone (PEEK) has been widely applied for orthopedic and oral implants due to its excellent mechanical properties, biocompatibility, and radiolucency. However, its bioinert and the lack of anti-microbial activity limit its application. We modified the PEEK surface with Ta/Cu co-implantation using plasma immersion ion-implantation technology. After implantation of Ta/Cu ions, the morphology and roughness of the PEEK surface were not significantly changed at micron level. We estimated the cytocompatibility, anti-microbial ability, and osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs) of the modified surfaces in vitro. Compared to the untreated surfaces, the Ta ion-treated surface showed improved adhesion, proliferation, ALP activity, ECM mineralization, and osteogenic gene expression of BMSCs. Further, the Cu ion-treated surface showed reduced initial adhesion and proliferation of Escherichia coli and Staphylococcus aureus in vitro and proliferation of Staphylococcus aureus in the mouse subcutaneous implant-associated infection model. According to a rat bone repair model, all Ta ion-implanted groups demonstrated improved new bone formation. In summary, Ta/Cu ion co-impanation improved anti-microbial activity and promoted osseointegration of the PEEK surface.

A 5' tRNA-Ala-derived small RNA regulates anti-fungal defense in plants.

Apart from their primordial role in protein synthesis, tRNAs can be cleaved to produce tRNA-derived small RNAs (tsRNAs). The biological functions of tsRNAs in plants remain largely unknown. In this study, we developed RtcB ligation-based small RNA (sRNA) sequencing, a method that captures and distinguishes between 3'-2',3'-cyclic-phosphate (cP)/phosphate (P)-terminated sRNAs and 3'-OH-terminated sRNAs, and profiled 5' tsRNAs and 5' tRNA halves in Arabidopsis thaliana. We found that Arabidopsis 5' tsRNAs and 5' tRNA halves predominantly contain a cP at the 3' end and require S-like RNase 1 (RNS1) and RNS3 for their production. One of the most abundant 5' tsRNAs, 5' tsR-Ala, by associating with AGO1, negatively regulates Cytochrome P450 71A13 (CYP71A13) expression and camalexin biosynthesis to repress anti-fungal defense. Interestingly, 5' tsR-Ala is downregulated upon fungal infection. Our study provides a global view of 5' tsRNAs and 5' tRNA halves in Arabidopsis and unravels an important role of a 5' tsRNA in regulating anti-fungal defense.

A calmodulin-binding transcription factor links calcium signaling to antiviral RNAi defense in plants.

RNA interference (RNAi) is an across-kingdom gene regulatory and defense mechanism. However, little is known about how organisms sense initial cues to mobilize RNAi. Here, we show that wounding to Nicotiana benthamiana cells during virus intrusion activates RNAi-related gene expression through calcium signaling. A rapid wound-induced elevation in calcium fluxes triggers calmodulin-dependent activation of calmodulin-binding transcription activator-3 (CAMTA3), which activates RNA-dependent RNA polymerase-6 and Bifunctional nuclease-2 (BN2) transcription. BN2 stabilizes mRNAs encoding key components of RNAi machinery, notably AGONAUTE1/2 and DICER-LIKE1, by degrading their cognate microRNAs. Consequently, multiple RNAi genes are primed for combating virus invasion. Calmodulin-, CAMTA3-, or BN2-knockdown/knockout plants show increased susceptibility to geminivirus, cucumovirus, and potyvirus. Notably, Geminivirus V2 protein can disrupt the calmodulin-CAMTA3 interaction to counteract RNAi defense. These findings link Ca2+ signaling to RNAi and reveal versatility of host antiviral defense and viral counter-defense.

Peroxidase- and UV-triggered oxidase mimetic activities of the UiO-66-NH2/chitosan composite membrane for antibacterial properties.

In this study, UiO-66-NH2 metal-organic framework (MOF) nanoparticles with peroxidase and oxidase mimetic activities were incorporated into a chitosan (CS) matrix by a simple and environmentally friendly method. The UiO-66-NH2/CS composite membrane possesses the peroxidase mimicking activity in the presence of traces of H2O2, thus resulting in good antibacterial properties. Intriguingly, 30 min of UV pre-irradiation of the UiO-66-NH2/CS composite membrane, in the absence of H2O2, still leads to a good antibacterial activity. This was attributed to the oxidase mimetic activity and the peroxidase mimicking activity of UiO-66-NH2. In such a way, the side effects of direct exposure to UV irradiation and H2O2 can be avoided for wound-healing treatments. The antibacterial mechanism was further proved by antibacterial experiments, TMB·2HCl color development experiments, reactive oxygen species generation tests and electron spin resonance tests. As a potential medical antibacterial dressing, in vitro membranes were also investigated.

Thermal conductivity and interfacial thermal resistance in the heterostructure of silicon/amorphous silicon dioxide: the strain and temperature effect.

This article reports the thermal conduction properties of Si/a-SiO2 heterostructure with two different interfaces: weak and strong coupling strength through molecular dynamics simulation. The size and temperature dependencies on the interfacial thermal resistance of the weak coupling interface are larger than those of the strong coupling interface. The thermal conduction in Si/a-SiO2 shows strong anisotropy. The thermal conductivity, interfacial thermal resistance, and enhancement of the anisotropy can be modulated by changing the strains applied to the heterostructures. This work provides an optional way to design the silicon-based heterostructures considering heat insulation and heat dissipation.

Effects of strain on thermal conductivity of silicon dioxide thin films using test method based on 3-ω technique and uniaxial strain setup.

We propose a test method to study the effects of strain on the thermal conductivity of thin films. First, a strain setup was designed to apply stress to a thin film, and a test system was built to measure its thermal conductivity by combining the strain setup with the 3-ω method. The strain setup can apply stress to the specimen by adjusting load weights, while the strain of a thin film was obtained by measuring the applied stress with a force sensor. Second, the effects of strain on the resistance and temperature coefficients of a metal thin film were studied using the strain setup and the four-wire resistance measurement method; the results show that the resistance and temperature coefficients of metal thin films decrease with strain. Finally, the effects of strain on the thermal conductivity of a silicon dioxide thin film and silicon substrate were studied using the proposed method and test system. As the strain increased from 0% to 0.072%, the thermal conductivity of the 300-nm thick silicon dioxide thin film decreased from 0.907 W/(m K) to 0.817 W/(m K). The thermal conductivity of the 0.5-mm thick silicon substrate fluctuated in the range of 130.6 W/(m K) to 118.8 W/(m K) and then tended to stabilize around 126.4 W/(m K).

Study on the osteogenesis of rat mesenchymal stem cells and the long-term antibacterial activity of Staphylococcus epidermidis on the surface of silver-rich TiN/Ag modified titanium alloy.

The main causes of failure of orthopedic implants are infection and poor bone ingrowth. Surface modification of the implants to allow for long-term antibacterial and osteogenic functions is an effective solution to prevent failure of the implants. We developed silver-rich TiN/Ag nano-multilayers on the surface of titanium alloy with different doses of Ag+ . The antibacterial stability and osteogenesis of the silver-rich surface were determined by evaluating the adhesion and proliferation of Staphylococcus epidermidis, and the adhesion, proliferation, alkaline phosphatase activity, extracellular matrix mineralization, and the expression level of genes involved in osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs). The results demonstrated that the antibacterial rates (Ra) of 5 × 1016 -Ag, 1 × 1017 -Ag, 5 × 1017 -Ag, and 1 × 1018 -Ag were respectively 46.21%, 85.66%, 94.99%, 98.48%, and 99.99%. After subcutaneous implantation in rats or immersion in phosphate buffered saline for up to 12 weeks, the silver-rich surface of the titanium alloy showed long-term stable inhibition of Staphylococcus epidermidis. Furthermore, in vitro and in vivo studies indicated that the Ag-implanted titanium did not show apparent cytotoxicity and that lower Ag+ implanted groups (5 × 1016 -Ag, 1 × 1017 -Ag) had better viability and biological safety when compared with higher Ag+ implanted groups. In addition, when compared with the Ti6Al4V-group, all Ag-implanted groups exhibited enhanced osteogenic indicators in rat BMSCs. Regarding osteogenic indicators, the surfaces of the 5 × 1017 -Ag group had better osteogenic effects than those of other groups. Therefore, the proper dose of Ag+ implanted TiN/Ag nano-multilayers may be one of the options for the hard tissue replacement materials with antibacterial activity and osteogenic functions.

Well-water-dispersed N-trimethyl chitosan/Fe3O4 hybrid nanoparticles as peroxidase mimetics for quick and effective elimination of bacteria.

Fe3O4 nanoparticles, used as peroxidase mimetics, exhibit splendid future in the biomedical field. However, the functionalization on Fe3O4 nanoparticles always goes with the loss of superparamagnetism and decrease in peroxidase-activity. Here, we synthesized green polyethylene glycol (PEG)-functionalized magnetic/N-trimethyl chitosan (CS) hybrid nanoparticles (Fe3O4@PAA/TMC/PEG NPs) with improved water dispersibility, superparamagnetism, high saturation magnetization and well peroxidase-like activity. The functionalized coating was divided in two steps, one involved a cross-linked PEG/PAA/CS middle layer to protect the nanocrystal Fe3O4 from oxidization, the other was a hydrophilic PEG/TMC outer layer improving the water dispersion, biocompatibility, as well as supplying positive quaternary ammonium groups for a potential increase of cell binding efficiency. The structure, composition and morphology of Fe3O4@PAA/TMC/PEG NPs were characterized by TEM, FT-IR spectroscopy, DLS, zeta potential measurement, respectively. Thermal performance was characterized by TGA, and the peroxidase-like mimics activity was tested by TMB·2HCl colour development experiments. The magnetic property of the as-prepared hybrid nanoparticles was first confirmed by VSM, and then proved by the bacterial pathogens adsorption, especially at ultralow pathogen concentration. Particularly, with an external magnet, the Fe3O4@PAA/TMC/PEG NPs, combined cationic quaternary ammonium groups and peroxidise-mimetic catalytic activity, were tested for antibacterial effect by plating method.

A potentiometric SO2 gas sensor based on the Li3PO4-Li2SiO3 solid electrolyte thin film.

A potentiometric sulfur dioxide (SO2) gas sensor based on the Li3PO4-Li2SiO3 solid electrolyte thin film was developed. The sensor was based on a galvanic cell O2, SO2, Au, Li2SO4-V2O5|Li3PO4-Li2SiO3|Au, SO2, O2. The Li3PO4-Li2SiO3 thin film was deposited on the Al2O3 substrate by RF magnetron sputtering, and the Au patterns were fabricated as the electrodes. The sensing electrode materials of Li2SO4-V2O5 with different dopants TiO2 and MgO were prepared, and as the ratio of Li2SO4:TiO2 is 1:1 (mol) with 5 wt. % V2O5 and 5 wt. % MgO, the sensor showed relatively good response characteristics to SO2 at 450 °C. Then, the sensor was further tested at the working temperature from 400 °C to 500 °C. The results show that the sensor has good response to SO2 at 400-450 °C, and the sensitivity is 90.15-57.19 mV/dec. The response and recovery times are 20-40 s and 2.5-4 min, respectively, when the gas concentration of SO2 increases from 10 ppm to 100 ppm and then decreases to 10 ppm. At 425 °C, the sensitivity is close to the theoretical values, and the final recovery potential of the sensor is almost consistent with the initial potential.

Study on the In Vitro and In Vivo Antibacterial Activity and Biocompatibility of Novel TiN/Ag Multilayers Immobilized onto Biomedical Titanium.

To determine the short- and long-term antibacterial properties of a novel biomedical titanium alloy to ensure excellent biocompatibility of the TiN/Ag multilayers loaded with different doses of Ag+. First, nanosized TiN/Ag multilayers were accumulated onto titanium alloy (Ti-6Al-4V) substrates via multi-arc ion plating. Then, the multilayers were implanted with different doses of silver ions (1×1017 ions/cm², 1×1018 ions/cm², 5×1016 ions/cm², and 5×1017 ions/cm²). Both short- and long-term antibacterial properties against Streptococcus mutans and Staphylococcus aureus were assessed via unique methods. Additionally, the response and behaviors of MC3T3-E1 and L929 cells on the different surfaces were evaluated by a variety of methods through comparison to a normal matched substrate (Ti-6Al-4V). In Vitro and In Vivo analyses revealed that the multilayers containing different doses of Ag ions effectively prevented bacterial adhesion and eliminated the majority of adhered bacteria in the initial period. In addition, the antibacterial activity of each TiN/Ag group improved with time, with the antibacterial rate (Ra) ultimately reaching 99% (antibacterial activity: 1 × 1018 ions/cm² > 5 × 1017 ions/cm² > 1 × 1017 ions/cm² > 5 × 1016 ions/cm²). All of the samples loaded with Ag+ exhibited good compatibility, as well as higher cell proliferation and lower apoptosis than the pure Ti-6Al-4V substrates. Considering both bacteriostasis and biocompatibility, 1 × 1017 ions/cm² and 5 × 1017 ions/cm² are the recommended doses for orthopedic and dental implants. The results indicate that all of the samples loaded with Ag+ possess excellent biocompatibility and antibacterial activity against common bacteria that cause implantation infection. The samples loaded with Ag+ can be implanted into soft and hard growing tissues to greatly improve the survival rate of orthopedic and dental implants.

Chloroplast-to-Nucleus Signaling Regulates MicroRNA Biogenesis in Arabidopsis.

As integral regulators in plant development and stress response, microRNAs (miRNAs) themselves need to be tightly regulated. Here, we show that tocopherols (vitamin E), lipid-soluble antioxidants synthesized from tyrosine in chloroplasts, positively regulate the biogenesis of miRNAs. Tocopherols are required for the accumulation of 3'-phosphoadenosine 5'-phosphate (PAP), a retrograde inhibitor of the nuclear exoribonucleases (XRN), which may protect primary miRNAs from being degraded and promote mature miRNA production. Such regulation is involved in heat-induced accumulation of miR398 and plant acquisition of heat tolerance. Our study reveals a chloroplast-to-nucleus signaling mechanism that favors miRNA biogenesis under heat and possibly other environmental perturbations.

Global identification of Arabidopsis lncRNAs reveals the regulation of MAF4 by a natural antisense RNA.

Long non-coding RNAs (lncRNAs) have emerged as important regulators of gene expression and plant development. Here, we identified 6,510 lncRNAs in Arabidopsis under normal or stress conditions. We found that the expression of natural antisense transcripts (NATs) that are transcribed in the opposite direction of protein-coding genes often positively correlates with and is required for the expression of their cognate sense genes. We further characterized MAS, a NAT-lncRNA produced from the MADS AFFECTING FLOWERING4 (MAF4) locus. MAS is induced by cold and indispensable for the activation of MAF4 transcription and suppression of precocious flowering. MAS activates MAF4 by interacting with WDR5a, one core component of the COMPASS-like complexes, and recruiting WDR5a to MAF4 to enhance histone 3 lysine 4 trimethylation (H3K4me3). Our study greatly extends the repertoire of lncRNAs in Arabidopsis and reveals a role for NAT-lncRNAs in regulating gene expression in vernalization response and likely in other biological processes.

Enhanced cell growth on 3D graphene scaffolds implanted with nitrogen ions.

One of the key challenges in engineering tissues for cell-based therapies is developing biocompatible scaffold materials to direct cell behavior. In this paper, the cytocompatibilities of a flexible three-dimensional graphene scaffold (3D-G) and the same scaffold implanted with nitrogen ions (N+/3D-G) are compared using an in vitro assay based on 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The N+/3D-G samples were prepared from low-temperature hydrothermally synthesized flexible 3D-G by ion implantation and were found to display improved adhesion and proliferation of rat osteoblast and mouse fibroblast cells. In particular, the N+/3D-G sample with a nitrogen content of ∼10% showed the highest levels of cell viability and proliferation. The flexible N+/3D-G has potential applications as a biocompatible scaffold material that provides improved surface area and hydrophilic groups for cell growth and proliferation.

Shape-Control of Three-Dimensional Self-Assembly Graphene by Hydrothermal Reaction Time and Its Biological Application.

In this paper, three-dimensional self-assembly graphene (3D-G) was prepared by the hydrothermal synthesis method, and 3D-G was designed as a suitable biological scaffold for cell growth and adhesion. The shape of 3D-G was tuned by adjusting the hydrothermal reaction time (6 h, 12 h, 18 h and 24 h). Then the scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses were used to characterize the microstructure and component of 3D-G, which showed that the length, diameter, pore size and defects of 3D-G were all decreased as the reaction-time increased. In vitro cell culture experiment, the cytocompatibility of 3D-G prepared under different hydrothermal reaction time was assessed using mouse fibroblast cells (L929) via 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT). Meanwhile, the cell adhesion, growth and proliferation were also observed by SEM. These results showed that the 3D-G with the reaction time of 24 h (3D-G/24 h) had the best cytocompatibility, which could be used as tissue scaffolds for cell growth.

N+ implantation induce cytocompatibility of shape-controlled three-dimensional self-assembly graphene.

AIM: The aim of the present research was to synthesize N+ implanted 3D self-assembly graphene (N+/3D-SGHs) to overcome the weaknesses of graphene (small sizes and poor hydrophilicity) in tissue engineering scaffolds. MATERIALS & METHODS: N+/3D-SGHs was achieved by ion implantation on one-step hydrothermal synthesized 3D self-assembly graphene (3D-SGHs), and N+/3D-SGHs with different doses of nitrogen ions (1 × 1016 ions/cm2, 1 × 1018 ions/cm2 and 1 × 1020 ions/cm2), which adjusted by nitrogen ion beam intensity. RESULTS: N+/3D-SGHs, as scaffolds, provide stereo space and hydrophilic groups for mouse-fibroblast cells (L929) growth and proliferation. Notably, N+/3D-SGHs with the N+ injected quantity of 1 × 1020 ions/cm2 displayed the highest protein-adhesion strength, cell viability and proliferation, which supported its good cytocompatibility. CONCLUSION: This study demonstrated N+/3D-SGHs as a promising and effective tissue scaffold that might have applications in biomedicine.

Ag+ implantation induces mechanical properties, cell adhesion and antibacterial effects of TiN/Ag multilayers in vitro.

AIM: This study aims to investigate the effect of Ag+ implantation dose on the structure, hardness, adhesion strength, friction resistance, cell adhesion and antibacterial effects of TiN/Ag multilayers. METHODS: Nanoscale TiN/Ag multilayers were deposited on Ti-6Al-4V substrates using multiarc ion plating. The multilayers were then implanted by Ag ions. RESULTS: A distinct multilayer structure and large titanium nitride grains with better (111) crystallinity were proved. The hardness and elastic modulus of the multilayer reached 32.2 and 318.9 GPa, respectively. The largest critical load was 32.5 mN, and the minimum friction coefficient was 0.092. The mechanical properties, the cell proliferation and antibacterial properties of the multilayers with Ag+ implantation were better than those without Ag+ implantation. CONCLUSION: Our results indicate that a dose of 1 × 1017 ions/cm2 induced an improvement in crystallinity, mechanical properties, as well as preferable cell adhesion and antibacterial effects.

Enhancement of interaction of L-929 cells with functionalized graphene via COOH+ ion implantation vs. chemical method.

Low hydrophilicity of graphene is one of the major obstacles for biomaterials application. To create some hydrophilic groups on graphene is addressed this issue. Herein, COOH+ ion implantation modified graphene (COOH+/graphene) and COOH functionalized graphene were designed by physical ion implantation and chemical methods, respectively. The structure and surface properties of COOH+/graphene and COOH functionalized graphene were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle measurement. Compared with graphene, COOH+/graphene and COOH functionalized graphene revealed improvement of cytocompatibility, including in vitro cell viability and morphology. More importantly, COOH+/graphene exhibited better improvement effects than functionalized graphene. For instance, COOH+/graphene with 1 × 1018 ions/cm2 showed the best cell-viability, proliferation and stretching. This study demonstrated that ion implantation can better improve the cytocompatibility of the graphene.