Search

• The mechanical characteristics of the sealing ring are determined through testing. • A three-dimensional model for simulating seal failure behavior is presented. • A combined seal structure with better sealing performance than O-rings is designed. • The optimum contact stress range for the combined seal structure is determined. The utilization of O-ring seal structures in landing gears has historically been associated with high rates of failure. Therefore, this study analyzes helicopter landing gear friction failures based on experimental and numerical simulations. The model is designed to replicate the failure phenomena including "seal extrusion", "seal leakage", "seal wear", and "seal distortion", and to further investigate causes of failure. Corresponding failure criteria are also presented. Addressing the deficiencies inherent in the original O-ring structure, three composite seal structures—namely, the VL seal, double triangle seal, and T-seal—are introduced to enhance the respective seal structure of the buffer pillar. The findings exhibit that, following the transition to the composite seal structure, the strain peaks are optimized. Finally, this paper offers optimal contact pressure ranges for the optimized seals. [ABSTRACT FROM AUTHOR]

• A ternary ECL immunoassay based on ABEI is designed for amyloid-β protein detection. • Flower-like Co-MOFs with peroxidase-like activity is used as coreaction accelerator. • Co-MOFs not only act as nanocarriers of ABEI, but also catalyze H 2 O 2 decomposition. • The synergistic catalysis of Co-MOFs and Au NPs realize the ECL signal amplification. In this work, a "luminophore/coreactant/co-reaction accelerator" ternary electrochemiluminescence (ECL) system is proposed by using N -(aminobutyl)- N -(ethylisoluminol) (ABEI) functionalized cobalt-based MOFs (Co-MOFs/ABEI) with superior peroxidase-like activities as the luminophore. ABEI, the derivative of luminol, is used as the reductant and organic ligand to synthesize flower-like Co-MOFs/ABEI. The as-synthesized Co-MOFs/ABEI not only function as desirable nano-carriers for the enrichment of ABEI, but also act as co-reaction accelerators for the catalysis of H 2 O 2 decomposition. Furthermore, Au nanoparticles are decorated on Co-MOFs/ABEI via electrostatics attraction, endowing it with favorable biocompatibility and electrocatalytic property to bond with detection antibodies and generate more excited state ABEI*. Besides, with the advantages of large specific surface area and easy preparation, Au nanoparticles functionalized Fe 3 O 4 @polypyrrole is utilized to anchor the capture antibodies for immunoaction with target analyte. Amyloid-β protein (Aβ 42), a principal hallmark of Alzheimer's disease, is chosen as the target analyte. The proposed Aβ 42 immunosensor performs with a broad linear range from 10 fg mL−1 to 100 ng mL−1 and a detection limit down to 3 fg mL−1, opens up new prospects for clinical analysis of Aβ 42 and provides promising approaches to synthesize luminophore-functionalized MOFs with high luminous efficiency for ECL bioanalysis. [ABSTRACT FROM AUTHOR]

Nutritional symbionts influence host reproduction, but the underlying molecular mechanisms are largely unclear. We previously found that the bacteriocyte symbiont Hamiltonella impacts the sex ratio of the whitefly Bemisia tabaci. Hamiltonella synthesizes folate by cooperation with the whitefly. Folate deficiency by Hamiltonella elimination or whitefly gene silencing distorted whitefly sex ratio, and folate supplementation restored the sex ratio. Hamiltonella deficiency or gene silencing altered histone H3 lysine 9 trimethylation (H3K9me3) level, which was restored by folate supplementation. Genome-wide chromatin immunoprecipitation-seq analysis of H3K9me3 indicated mitochondrial dysfunction in symbiont-deficient whiteflies. Hamiltonella deficiency compromised mitochondrial quality of whitefly ovaries. Repressing ovary mitochondrial function led to distorted whitefly sex ratio. These findings indicate that the symbiont-derived folate regulates host histone methylation modifications, which thereby impacts ovary mitochondrial function, and finally determines host sex ratio. Our study suggests that a nutritional symbiont can regulate animal reproduction in a way that differs from reproductive manipulators. [Display omitted] • Folate deficiency by elimination of a bacteriocyte symbiont distorts whitefly sex ratio • Symbiont deficiency activates the histone H3 lysine 9 trimethylation (H3K9me3) level • H3K9me3 modification impairs ovary mitochondrial quality in symbiont-cured whiteflies • Repressing ovary mitochondrial function inhibits fertilization, distorting host sex ratio Yao et al. find that a bacteriocyte symbiont-derived folate regulates the ovary mitochondrial function by histone methylation modification, leading to a female-biased sex ratio of the whitefly, which benefits symbiont vertical transmission. This study highlights the important role of symbiont-mitochondria associations in the regulation of host sex ratio. [ABSTRACT FROM AUTHOR]

Netflix is a leading digital streaming platform that provides a variety of content to users. Netflix charges a fixed amount from its users for its services. Unlike other digital streaming platforms, Netflix does not support subscriptions supported by ads; consequently, Netflix's subscriptions are decreasing. However, Netflix does not offer ad-supported subscriptions. In this context, we aimed to explain why Netflix does not provide them by modelling a monopolist's decision-making using asymmetric information. We compared a shutdown policy with other strategies using the first-best contract with complete information as the benchmark. The results indicate a close relationship between the customer base and the efficiency of the shutdown policy. This outcome at least partly explains Netflix's choice of strategy, its past success, and its current dilemma. • Links between customer base and offering of ad-supported subscriptions • Several high-value customers benefit Netflix to close ad-supported subscriptions. • Netflix should reconsider commercials with declining subscribers. [ABSTRACT FROM AUTHOR]

[Display omitted] • DOP consisted of D-mannose, D-glucose, and D-galactose in a mole ratio of 3:2:1. • DOP possesses antitumor and immunomodulation activity. • DOP enhanced NK cell and CTL activity and increased the non-specific and tumor antigen-specific antibody titers. • DOP could inhibit the growth of S180 tumors by improving the tumor immune microenvironment. This study aims to explore the structural features and anti-tumor and immunomodulation activity of polysaccharides from Dendrobium officinale that were prepared using DEAE Sephadex A-50 and Sephadex G100. DOP structure was characterized using colorimetry, HPGPC, GC–MS, FT-IR, and NMR. The molecular weight of DOP was 1.89 × 105 Da. And the DOP consisted of D-mannose, D-glucose, and D-galactose in a mole ratio of 3:2:1. DOP could inhibit the growth of S180 tumors by promoting splenocytes proliferation, enhancing NK cell and CTL activity, and increasing the non-specific and tumor antigen-specific antibody levels. These findings suggested that DOP might be a potential antitumor agent with immunomodulatory activity. [ABSTRACT FROM AUTHOR]

Abstract: High rate Li3V2(PO4)3/C composite with excellent electrochemical performance has been successfully synthesized via a sample carbon thermal method using meso-tetraphenyl porphyrin (TPP) as carbon source. The as prepared Li3V2(PO4)3/C composite delivers a reversible capacity of 103.71mAhg−1 at 20C charge/discharge rate. The Li+ diffusion coefficient ranges from 10−9 to 10−10 cm2 s−1 based on different scanning rates. The excellent high rate performance may attribute to the small particle size of the LVP/C and the carbon derived from thermal decomposition of TPP. In addition, its application in the full-cell, Li3V2(PO4)3‖Li4Ti5O12, is also presented and discussed. [Copyright &y& Elsevier]

Abstract: The SnO2-doped Cu2O has been produced in aqueous solution using hydrazine as the reducing agent. Techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–vis spectroscopy were used to comprehend the relation between structure and properties of the SnO2-doped Cu2O. The effects of SnO2 insertion on the Cu2O photo-catalytic activity for the degradation of trifluralin were reported here. The results show that SnO2-doping can greatly enhance catalytic activity of Cu2O nano-crystals. [Copyright &y& Elsevier]

Nowadays, brain natriuretic peptide (BNP-32) is fundamental to early cardiovascular clinical diagnosis, whose accurate assay is of significance by photoelectrochemistry (PEC) for the low background and high precision. Herein, a novel enhanced PEC platform was built by successive deposition of N-doped ZnO nanopolyhedra (N–ZnO NP) and protoporphyrin IX (PPIX). Specifically, the N–ZnO NP with a narrow bandgap of 2.60 eV was synthesized by direct calcination of zeolitic imidazole framework-8 (ZIF-8), and performed as the substrate to enhance the photocurrents of PPIX (as photosensitizer) whose photoelectron transfer pathway and enhanced PEC mechanism were studied in detail. Under such foundation, a label-free PEC aptasensor was developed by deposition of DNA aptamer onto the PEC platform and then ultrasensitive assay of BNP-32 based on a "signal off" model. The biosensor showed a wide linear range (1 pg mL−1- 0.1 μg mL−1) with a limit of detection (LOD) as low as 0.14 pg mL−1. This doping technique of ZnO nanomaterials provides some valuable guidelines for synthesis of advanced PEC probes in bioanalysis. [Display omitted] • The N–ZnO NP was prepared by directly calcining the ZIF-8 and adopted to enhance the photocurrent of PPIX. • The PEC platform was constructed by successive deposition of PPIX and N–ZnO NP to largely promote the photoelectron transfer. • A label-free PEC aptasensor was built for ultrasensitive assay of BNP-32 protein. [ABSTRACT FROM AUTHOR]

The rapid and reliable measurement of procalcitonin (PCT) level exerts a prominent impact on controlling infections and preventing septicemia. This work presents a "signal on-off" electrochemiluminescence (ECL) immunosensor for ultrasensitive PCT detection based on the double quenching effects of Fe 3 O 4 @PDA-Cu x O towards a self-enhanced Ru (bpy) 3 2+-functionalized metal organic framework (MOF). Specifically, mesoporous and hollow MIL-101(Al)–NH 2 is first applied in ECL system to load Ru (bpy) 3 2+ abundantly and stably. Poly (ethylenimine), as the coreactant, is covalently linked with MIL-101(Al)–NH 2 to prevent the leakage of Ru (bpy) 3 2+ and form a self-enhanced Ru complex, thus strong and stable ECL signals are obtained initially. To achieve high-efficiency quenching of "signal on" state, Fe 3 O 4 @PDA-Cu x O-Ab 2 is synthesized tactfully as the quenching probe by which catechol or benzoquinone units in PDA and Cu2+ adsorbed by PDA quench the excited states of Ru (bpy) 3 2+ via electron transfer and resonance energy transfer. In this way, a rapid and robust signal-quenched type ECL immunosensor is developed for PCT measurement with a detection limit of 0.18 pg mL−1 and a dynamic range from 0.0005 ng mL−1 to 100 ng mL−1. Given desirable selectivity, stability and reproducibility, the elaborated ECL immunoassay based on luminescence-functionalized MOF prefigures its great promise in bioanalysis of PCT and other biomarkers. • Mesoporous and hollow MIL-101(Al)–NH 2 is applied in ECL system for the first time. • A self-enhanced ECL complex is prepared by linked PEI with Ru functionalized MOF. • Fe 3 O 4 @PDA-Cu X O can quench Ru (bpy) 3 2+∗ via electron and energy transfer. • Sensitive procalcitonin detection is obtained with good selectivity and stability. [ABSTRACT FROM AUTHOR]

Creases and folds in Chinese paintings and calligraphies scrolls are hard to avoid during the handling in storage and exhibitions. The creases are usually reinforced with paper strips in the conservation treatment. However, adhering the paper strips will create unwanted secondary creases along the joining edge on the painting scrolls after repeated openings and rolling. This study proposes a new consolidant, bacteria cellulose (BC), for the conservation of creased Chinese painting scrolls. Different tests were carried out and the results showed that BC was a better approach than the traditional paper strip reinforcement method. The method not only had an excellent effect on conserving the creased artwork on Xuan-paper aesthetically, but also improved its physical properties. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ultrasensitive electrochemical aptasensor was developed for detecting Pb2+. • Au@p-rGO was applied as support for immobilizing the aptamer. • Au NPs@GO as signal probe exhibited high electrocatalytic activity towards H 2 O 2. • The aptasensor displayed low detection limit of 1.67 pmol/L for Pb2+. Abstract A sensitive electrochemical aptasensor was designed based on gold modified graphene nanocomposite with different morphologies for the detection of lead ion (Pb2+). Specifically, a sulfydryl-labeled substrate strand (Apt1) and a sulfydryl-labeled catalytic strand (Apt2) were devised in fabricating the electrochemical aptasensor. Gold modified porous reduced graphene oxide (Au@p-rGO) was synthesized and applied as support for immobilizing the Apt1. And gold modified graphene oxide (Au NPs@GO) was employed as signal probe and connected with Apt2 to realize the immobilization of it on the electrode by means of the principle of complementary base pairing. The current signal can be obtained by recording the electrocatalytic conditions toward H 2 O 2. The Pb2+-dependent DNAzyme could play a role when Pb2+ existed. With the increase of the concentration of Pb2+, the current response revealed a diminishing signal, thus realizing the sensitive detection of Pb2+. Under the optimal conditions, the fabricated electrochemical aptasensor exhibited a linear response toward Pb2+ ranging from 5 pmol/L to 1 μmol/L, together with a low limit of detection of 1.67 pmol/L. Moreover, the prepared aptasensor displayed outstanding selectivity, acceptable stability and superior reproducibility for detecting Pb2+. This proposed tactics may provide reference and potential applications for detecting some other heavy metal ions. [ABSTRACT FROM AUTHOR]