Effect of specimen thicknesses on water absorption and flexural strength of CFRP laminates subjected to water or alkaline solution immersion

In this paper, an experimental research was undertaken to investigate the effect of specimen thicknesses on water absorptions and flexural strengths of wet lay-up CFRP laminates subjected to distilled water or alkaline solution immersion up to 180 days. Test results showed that the water uptake and flexural strength retention of CFRP laminates were significantly affected by the adopted specimen thickness. For the same aging time, the water uptake of CFRP laminates decreased in the early stage of immersion and increased in the later stage of immersion with the increase of specimen thickness. Meanwhile, the flexural strength retention generally increased as specimen thickness increased. In addition, a new thickness-based accelerated method for hygrothermal aging test of CFRP laminates was proposed. The accelerated factors of the water uptake and flexural strength retention of CFRP laminates were theoretically deduced. The proposed analytical model of accelerated factors was verified with current test data, and then applied to predict long-term properties of CFRP laminates. Compared with the traditional temperature-based accelerated method, the new thickness-based accelerated method is much easier to apply to predict long-term properties of CFRP laminates with good accuracy

A new thickness-based accelerated aging test methodology for resin materials: theory and preliminary experimental study

This paper proposes a novel accelerated test method based on the thickness of resin materials. This method is to overcome the adverse influence of high temperature on the reliability of experimental results of the accelerated tests widely adopted in the current practice. To verify the proposed thickness-based accelerated method (ThAM), an experimental investigation was conducted focusing on the water absorption and tensile properties of epoxy resin. The results suggest that the existing temperature-based accelerated method (TAM) cannot be applied when the test temperature is high as in this case the degradation mechanism of materials is probably changed. The acceleration factor of TAM is greatly dependent on the type of test solution, which further limits the application in the accelerated test. Compared with TAM, the new method is much easier to apply, and more stable and reasonable to accelerate the aging test of epoxy resin

Targeting GSTP1-dependent ferroptosis in lung cancer radiotherapy: Existing evidence and future directions

Radiotherapy is applied in about 70% patients with tumors, yet radioresistance of tumor cells remains a challenge that limits the efficacy of radiotherapy. Ferroptosis, an iron-dependent lipid peroxidation regulated cell death, is involved in the development of a variety of tumors. Interestingly, there is evidence that ferroptosis inducers in tumor treatment can significantly improve radiotherapy sensitivity. In addition, related studies show that Glutathione S-transferase P1 (GSTP1) is closely related to the development of ferroptosis. The potential mechanism of targeting GSTP1 to inhibit tumor cells from evading ferroptosis leading to radioresistance has been proposed in this review, which implies that GSTP1 may play a key role in radiosensitization of lung cancer via ferroptosis pathway

Efficient Chemoenzymatic Synthesis of an N-glycan Isomer Library

Quantification, characterization and biofunctional studies of N-glycans on proteins remain challenging tasks due to the complexity, diversity and low abundance of these glycans. The availability of structurally defined N-glycan (especially isomer) libraries is essential to help solve these tasks. We report herein an efficient chemoenzymatic strategy, namely Core Synthesis/Enzymatic Extension (CSEE), for rapid production of diverse N-glycans. Starting with 5 chemically prepared building blocks, 8 N-glycan core structures containing one or two terminal N-acetyl-D-glucosamine (GlcNAc) residue(s) were chemically synthesized via consistent use of oligosaccharyl thioethers as glycosylation donors in a convergent fragment coupling strategy. Each of these core structures was then extended to 5 to 15 N-glycan sequences by enzymatic reactions catalyzed by 4 robust glycosyltransferases. Success in synthesizing N-glycans with Neu5Gc and core-fucosylation further expanded the ability of the enzymatic extension. Meanwhile, high performance liquid chromatography with an amide column enabled rapid and efficient purification (\u3e98% purity) of N-glycans in milligram scales. A total of 73 N-glycans (63 isomers) were successfully prepared and characterized by MS2 and NMR. In summary, the CSEE strategy provides a practical approach for “mass production” of structurally defined N-glycans, which are important standards and probes for glycoscience

Microstructure regulation of lignite-based hard carbons and their sodium storage properties

The diversified clean and high-value utilization of coal plays an important role in promoting the low-carbon sustainable development of China's coal industry, and the materialization of coal is one of the important ways to enhance the level of its clean and efficient utilization. In this study, lignite-based hard carbons (LHC) were prepared by high-temperature carbonization (1000−1600 ℃) method using Huating lignite as precursor, taking full advantage of lignite's aromatic ring structure, well-developed primary pores and abundant surface active groups. The formation mechanism and evolution behavior of graphite-like microcrystals and defect structures including amorphous carbon, nanopores, and surface functional groups in LHC was explored, while the influence of carbonization temperature on the microstructure of LHC was further revealed. The electrochemical performance of different LHC as anode for sodium ion batteries (SIBs) was also tested by galvanostatic charge/discharge, galvanostatic intermittent titration and cyclic voltammetry, the influence mechanism of microstructure on the electrochemical sodium storage performance of anode materials was explored, and the electrochemical sodium storage mechanism of LHC was eventually elucidated. The results show that graphite-like microcrystalline structure and defective structures such as amorphous carbon, nanopores, and oxygen/nitrogen-containing functional groups of LHC can be effectively regulated by adjusting the carbonization temperature. When the carbonization temperature was 1400 ℃, the LHC-1400 was rich in graphite-like microcrystals with reasonable layer spacing (0.371 nm), and also had appropriate amorphous carbon and nanopores with a specific surface area of 4.92 m2/g, and oxygen/nitrogen-containing functional groups including C—O, C=O, O—C=O, pyridinic-N, pyrrolic-N, graphitic-N. The LHC-1400 as anode for SIBs can deliver a high reversible capacity of 275 mAh/g, and has a reversible capacity of 111 mAh/g at a current density of 0.2 A/g with a capacity retention rate 96% after 200 cycles, which exhibits good rate performance and cycle stability. The excellent sodium storage performance of LHC is closely related to the functions and roles of their different microstructures. The graphite-like microcrystals with reasonable layer spacing in LHC can provide a transport channel for the rapid intercalation and de-intercalation of Na+ to provide capacity with intercalated sodium storage; the defect structures such as amorphous carbon, open nanopores, and oxygen/nitrogen-containing in LHC can provide sufficient active sites for Na+ storage to contribute capacity by adsorption, and a small amount of closed pores in LHC can provide sufficient space for the storage of Na+ and supply sodium storage capacity by pore filling. The “adsorption-insertion-filling” sodium storage methods in LHC are synergistic with each other to realize its efficient electrochemical energy storage

Threshold Strategy for Nonsmooth Filippov Stage-Structured Pest Growth Models

In order to control pests and eventually maintain the number of pests below the economic threshold, in this paper, based on the nonsmooth dynamical system, a two-stage-structured pest control Filippov model is proposed. We take the total number of juvenile and adult pest population as the control index to determine whether or not to implement chemical control strategies. The sliding-mode domain and conditions for the existence of regular and virtual equilibria, pseudoequilibrium, boundary equilibria, and tangent points are given. Further, the sufficient condition of the locally asymptotic stability of pseudoequilibrium is obtained. By numerical simulations, the local bifurcations of the equilibria are discussed. Our results show that the total number of pest populations can be successfully controlled below the economic threshold by taking suitable threshold policy

A novel silica aerogel/porous Y2SiO5 ceramics with low thermal conductivity and enhanced mechanical properties prepared by freeze casting and impregnation

A novel silica aerogel/porous Y2SiO5 composite as prepared by freeze casting and sol-gel impregnation. Porous Y2SiO5 ceramics with different solids contents were prepared at 1400 ̊C. The pore structure, porosity and mechanical properties of the porous Y2SiO5 ceramics before and after impregnating of silica aerogel were investigated. The results show that the room-temperature thermal conductivity decreases and the compressive strength increases remarkably while impregnating porous Y2SiO5 with silica aerogel. The silica aerogel/porous Y2SiO5 composite exhibits a high compressive strength (i.e. 9.3 MPa) and a low thermal conductivity (i.e. 0.260 W/mK)). This work reports an optimal processing method of silica aerogel/porous Y2SiO5 composite with the potential application as a high-temperature thermal insulation material

Numerical study on the smoke movement and control in main roadway for mine fires occurred in branch

Mine exogenous fire is the main disaster in coal mines. Owing to the complicated structure and the ventilation network, the smoke movement and control in branched roadway fires of coal mines is more complicated than that in traffic tunnel fires. In this study, the smoke backlayering length and critical velocity in a main roadway for fires that occurred in a branch were studied with varying fire locations. The results suggest that the smoke from the branch does not spread along the width centerline of the main roadway, but forms an early “snake-shaped” structure. The variation of dimensionless backlayering length with the dimensionless variable ln(Q˙*1/3/V*) is divided into two regions with different slopes by the line of L* = 1.6. Besides, branched roadway fires have a lower backlayering length and critical velocity compared to single-hole tunnel fires. These two parameters increase with decreasing the fire-node distance. Combined with dimensionless analysis and simulation results, calculation models considering fire location were proposed to estimate the smoke backlayering length and critical velocity. The credibility of prediction models is validated by comparing them with simulation results. The outcomes of the current study guide smoke control in similar-structured mine roadways and traffic tunnels