•The resistive ignition experiments of ADN based liquid propellant were conducted.•Comparison investigation was done in inert gas and oxidizing gas atmospheres.•Ignition delay time and burning ...duration of ADN based liquid propellant were studied.•The variation of droplet equivalent diameter of ADN based liquid propellant was analyzed.
An experimental investigation was performed to study combustion characteristics of ADN based liquid propellant droplet with resistive ignition method. The experiment was conducted in Ar atmosphere and different oxidizing gas atmospheres under an on-load voltage range of 190–230 V; the oxidizing gases included N2O, NO and O2. The influence of the atmosphere, on-load voltage, droplet volume on the ignition energy, ignition delay time, burning duration, and droplet equivalent diameter development during ignition and combustion was studied. ADN based liquid propellant showed feasibility to combustion by the resistive ignition method in the inert gas atmosphere. The ignition energy accounted for more than 80 % of the total energy during the ignition and combustion process. With the increase of the droplet volume, the value of the ignition delay time and burning duration increased. The atmosphere had a significant influence on the burning duration and droplet diameter, but had little influence on the ignition delay time. Under our experiment conditions, the N2O and O2 atmospheres improved the combustion process, while, the NO atmosphere inhibited the oxidation of methanol.
The combination of nanostructures with biomolecules leading to the generation of functional nanosystems holds great promise for biotechnological and biomedical applications. As a naturally occurring ...biomacromolecule, DNA exhibits excellent biocompatibility and programmability. Also, scalable synthesis can be readily realized through automated instruments. Such unique properties, together with Watson-Crick base-pairing interactions, make DNA a particularly promising candidate to be used as a building block material for a wide variety of nanostructures. In the past few decades, various DNA nanostructures have been developed, including one-, two- and three-dimensional nanomaterials. Aptamers are single-stranded DNA or RNA molecules selected by Systematic Evolution of Ligands by Exponential Enrichment (SELEX), with specific recognition abilities to their targets. Therefore, integrating aptamers into DNA nanostructures results in powerful tools for biosensing and bioimaging applications. Furthermore, owing to their high loading capability, aptamer-modified DNA nanostructures have also been altered to play the role of drug nanocarriers for in vivo applications and targeted cancer therapy. In this review, we summarize recent progress in the design of aptamers and related DNA molecule-integrated DNA nanostructures as well as their applications in biosensing, bioimaging and cancer therapy. To begin with, we first introduce the SELEX technology. Subsequently, the methodologies for the preparation of aptamer-integrated DNA nanostructures are presented. Then, we highlight their applications in biosensing and bioimaging for various targets, as well as targeted cancer therapy applications. Finally, we discuss several challenges and further opportunities in this emerging field.
Education informatization is an important initiative for the country to realize education modernization, which is related to the development of China’s education. The use of a single evaluation of ...teaching effectiveness obviously cannot meet the assessment needs. Based on the premise of intelligent assistance through a hybrid brain-computer interface, this paper aims to study an evaluation method for teaching effectiveness using artificial intelligence. Firstly, EEG signals are collected through an EEG acquisition device, and then they are preprocessed. Second, the pre-processed signals are subjected to feature extraction, and then the features are classified using a specific pattern recognition method, and finally the classification results are used to assess the effectiveness of English teaching for college students. Based on the evaluation results, the learning system is optimized and improved. The signals collected by EEG devices carry a lot of noise, and in this paper, the processing of the original signals includes a smoothing filter, de-baseline filter, filter filter, and Kalman filter to achieve a higher signal-to-noise ratio. Multivariate evaluation results are provided by the evaluation system that is assisted by artificial intelligence. Compared with other evaluation methods to enrich the evaluation information, based on the above system effectiveness evaluation study, as far as the F1 value is concerned, this paper’s method is the highest, reaching 0.815, which is 0.048 higher than the highest F1 value of the traditional algorithm, and in the other two values, this paper’s method is also higher than other methods. This verifies the rationality and effectiveness of the teaching effectiveness evaluation system based on a hybrid brain-computer interface proposed in this paper.
Covalent organic frameworks (COFs) are attractive candidates for advanced water‐treatment membranes owing to their high porosity and well‐organized channel structures. Herein, the continuous ...two‐dimensional imine‐linked COF‐LZU1 membrane with a thickness of only 400 nm was prepared on alumina tubes by in situ solvothermal synthesis. The membrane shows excellent water permeance (ca. 760 L m−2 h−1 MPa−1) and favorable rejection rates exceeding 90 % for water‐soluble dyes larger than 1.2 nm. The water permeance through the COF‐LZU1 membrane is much higher than that of most membranes with similar rejection rates. Long‐time operation demonstrates the outstanding stability of the COF‐LZU1 membrane. As the membrane has no selectivity for hydrated salt ions (selectivity <12 %), it is also suitable for the purification of dye products from saline solutions. The excellent performance and the outstanding water stability render the COF‐LZU1 membrane an interesting system for water purification.
Color filter: A continuous, high‐quality two‐dimensional imine‐linked COF membrane with ordered and tunable pore channels was prepared on tubular alumina supports. The COF‐LZU1 membrane shows excellent water permeance and high rejection rates for various water‐soluble dyes, as well as high stability during water purification.
A multifunctional nanosystem, which integrates biosensing, bioimaging, and therapeutic functions into a single nanoprobe, is of great significance for biosensing and biomedicine. Near-infrared (NIR) ...graphene quantum dots (GQDs) have emerged as an attractive bioimaging and therapy tool for exploring biological events because they can provide deep imaging penetration and low fluorescence background and produce 1O2 for PDT. Here, we reported a GQD-based multifunctional two-photon nanoprobe for intracellular tumor-related glutathione (GSH) detection and enhanced photodynamic therapy by reducing GSH levels in cancer cells. By taking the excellent quenching property of MnO2 nanosheets and the reduction ability of GSH, a GQD@MnO2 nanoprobe was developed through adsorption of MnO2 nanosheets onto the surface of GQDs for sensing intracellular tumor-related GSH. The nanoprobe shows a highly sensitive response to GSH in aqueous solutions with a detection limit of 83 nM. It also exhibits a high selectivity toward GSH relative to other biomolecules and electrolytes. In addition, once endocytosed, the MnO2 nanosheets are reduced by intracellular GSH, simultaneously releasing GQDs and decreasing the level of GSH for highly efficient PDT.
Transition metal‐based nitrogen‐doped carbon (M‐Nx‐C) is considered as a promising catalyst for the oxygen reduction reaction (ORR) in clean energy storage and conversion devices. Herein, ZnCo ...dual‐atomic sites are incorporated in hierarchical N‐doped carbon (HNC), with 1D nanotubes wrapped in 2D nanosheets structure (termed as 1D@2D ZnCo‐HNC), via a one‐step bio‐inspired pyrolysis. The feeding ratio of Zn to Co precursor and pyrolytic temperature are critically modulated to achieve well‐defined morphologies of the products, endowing them with the integrated merits of nanotubes and nanosheets as efficient ORR catalysts. Benefiting from the particular structure and electronic regulation of Zn on Co, the ZnCo‐Nx dual‐atomic system exhibits excellent ORR catalytic characteristics with an onset potential of 1.05 V and a half‐wave potential of 0.82 V. Density functional theory calculations further explain the regulating role of Zn, such that the adjusted Co in ZnCo‐Nx sites significantly reduces the energy cost to ultimately facilitate the ORR. Moreover, the Zn–air battery assembled with ZnCo‐HNC is capable of delivering the maximum power density of 123.7 mW cm−2 and robust stability for 110 h (330 cycles). This method provides a promising strategy for fabricating efficient transition metal‐based carbon catalysts for green energy devices.
With the unique 1D@2D structure and abundant ZnCo dual‐atomic sites, bio‐inspired ZnCo‐HNC exhibits excellent catalytic performances for the oxygen reduction reaction and a home‐assembled Zn–air battery. Density functional theory calculations further demonstrate that Co is the main active center in the ZnCo‐Nx system, while Zn serves as the charge adjuster.
Clear cell renal cell carcinoma (ccRCC) is a common and aggressive subtype of renal cancer. Here we conduct a comprehensive proteogenomic analysis of 232 tumor and adjacent non-tumor tissue pairs ...from Chinese ccRCC patients. By comparing with tumor adjacent tissues, we find that ccRCC shows extensive metabolic dysregulation and an enhanced immune response. Molecular subtyping classifies ccRCC tumors into three subtypes (GP1-3), among which the most aggressive GP1 exhibits the strongest immune phenotype, increased metastasis, and metabolic imbalance, linking the multi-omics-derived phenotypes to clinical outcomes of ccRCC. Nicotinamide N-methyltransferase (NNMT), a one-carbon metabolic enzyme, is identified as a potential marker of ccRCC and a drug target for GP1. We demonstrate that NNMT induces DNA-dependent protein kinase catalytic subunit (DNA-PKcs) homocysteinylation, increases DNA repair, and promotes ccRCC tumor growth. This study provides insights into the biological underpinnings and prognosis assessment of ccRCC, revealing targetable metabolic vulnerabilities.
Two-dimensional graphitic carbon nitride nanosheets (CNNSs) with planar graphene-like structure have stimulated increasingly research interest in recent years due to their unique physicochemical ...properties. CNNSs possess superior stability, high fluorescence quantum yield, low-toxicity, excellent biocompatibility, unique electroluminescent and photoelectrochemical properties, which make them appropriate candidates for biosensing. In this review, we first introduce the preparation and unique properties of CNNSs, with emphasis on their superior properties for biosensing. Then, recent advances of CNNSs in photoelectrochemical biosensing, electrochemiluminescence biosensing and fluorescence biosensing are highlighted. An additional attention is paid to the marriage of CNNSs and nucleic acids, which exhibits great potentials in both biosensing and intracellular imaging. Finally, current challenges and opportunities of this 2D material are outlined. Inspired by the unique properties of CNNSs and their advantages in biological applications, we expect that more attention will be drawn to this promising 2D material and extensive applications can be found in bioanalysis and diseases diagnosis.
•Advance of two-dimensional graphitic carbon nitride nanosheets (CNNSs) was present.•The deep research on CNNSs offers valuable strategies for biosensing applications.•Properties of CNNSs and their applications in biosensing were discussed in detail.•Deficiencies and perspectives about the applications of CNNSs were summarized.
Covalent organic frameworks (COFs) have been proposed as alternative candidates for molecular sieving membranes due to their chemical stability. However, developing COF membranes with narrowed ...apertures close to the size of common gas molecules is a crucial task for selective gas separation. Herein, we demonstrate a new type of a two-dimensional layered-stacking COF–COF composite membrane in bilayer geometry synthesized on a porous support by successively regulating the growth of imine-based COF-LZU1 and azine-based ACOF-1 layers via a temperature-swing solvothermal approach. The resultant COF-LZU1–ACOF-1 bilayer membrane has much higher separation selectivity for H2/CO2, H2/N2, and H2/CH4 gas mixtures than the individual COF-LZU1 and ACOF-1 membranes due to the formation of interlaced pore networks, and the overall performance surpasses the Robeson upper bounds. The COF-LZU1–ACOF-1 bilayer membrane also shows high thermal and long-time stabilities.
In recent years, the rapid growth of electric vehicle (EV) ownership in China has led to the large-scale retirement of power batteries. Establishing an effective recycling system for spent power ...batteries is a critical task. Therefore, we investigate the recycling mode selection and the carbon abatement decision in a closed-loop supply chain (CLSC) of EV power batteries under the carbon cap-and-trade policy. We propose four mixed-channel recycling modes in which two or three parties from a retailer, a third-party recycler and an echelon utilization enterprise participate in the recycling business. In the reverse chain, the collected spent power batteries are classified, wherein the echelon-utilizable batteries are processed into echelon utilization products for sale by the echelon utilization enterprise, while both the non-echelon-utilizable batteries and the post-echelon-utilized batteries are transferred to the manufacturer for extracting raw materials to produce new power batteries. We obtain equilibrium results by solving Stackelberg game models. The results reveal that when the competition intensity among recycling channels is below a certain threshold and the recycling price sensitivity is above a certain threshold, the optimal mode is the simultaneous participation of the retailer, the third-party recycler, and the echelon utilization enterprise. Otherwise, the optimal mode is the echelon utilization enterprise recycling with the retailer or third-party recycler. Higher recycling channel competition and lower recycling price sensitivity reduce the total recycling quantity. Higher carbon trading price, a lower investment cost coefficient for carbon abatement and increased consumers' low-carbon awareness will encourage the manufacturer to implement carbon reduction activities, thus reducing total carbon emissions. In addition, the engagement of the echelon utilization enterprise in the recycling business has a positive effect on relieving the recycling pressure and improving the manufacturer's profit.
•Recycling and partial echelon utilization of EV spent power batteries are studied.•Four multi-channel recycling modes are considered and compared.•The carbon abatement decision under the carbon cap-and-trade policy is studied.•Stackelberg game models are established to obtain equilibrium outcomes.•It is better for echelon utilization enterprises to recycle spent power batteries.
