Poor Thermal Stability Research Articles

Boosting Li-Ion Conductivity of Fluoride Solid Electrolyte by Low-Temperature Molten Salt Ablation and Particle Boundary Doping.

Halide solid electrolytes (SEs) are attracting great attention, owing to their high ionic conductivity and excellent high-voltage compatibility. However, severe moisture sensitivity, poor thermal stability, and instability at the lithium metal anode interface with chloride and bromide SEs retard their applications in solid-state lithium metal batteries. Fluoride SEs are expected to solve these problems, but they are now plagued by inadequate room-temperature (RT) ionic conductivity. Herein, a low-temperature molten salt (LiCl+1.33AlCl3) ablation method is proposed to enhance the ionic conductivity of monoclinic Li3GaF6 by particle boundary doping. The RT ionic conductivity of Li3GaF6 is correspondingly increased by 2 orders of magnitude, and the conductivity reaches 10-4 S cm-1 at 60 °C. The improved ionic conductivity benefits from the enhancement of interfacial ion transport, with the formation of more conductive chlorine-doped Li3GaF6-xClx and in situ binder LiAlCl4 to cement surrounding nanoparticles. The as-synthesized Li3GaF6 demonstrates outstanding humidity tolerance without conductivity degradation after exposure to a relative humidity of up to 35%. It also exhibits the widest electrochemical stability window experimentally (close to 6 V) compared with other state-of-the-art SEs. The solid-state Li/Li3GaF6/LiFePO4 cell with a stable Li+-conductive polymer interface is successfully driven for at least 200 cycles at 0.5C. Our study provides a solution to various chemical and electrochemical stability issues encountered by the halide SE family.

Low temperature machining advantages for sintered NdFeB magnets: A comparative experimental study of WAWJ with laser and WEDM

Sintered NdFeB magnets exhibit excellent magnetic properties and high reliability, making them widely used in fields such as new energy vehicles and electronic communications. However, NdFeB magnets have a low Curie temperature and poor thermal stability. Common machining methods such as laser cutting and EDM (Electrical Discharge Machining) often involve cutting temperatures in the hundreds or even thousands of degrees Celsius, leading to defects such as melting and cracks on the magnet surface. These defects degrade the surface quality and magnetic properties of the magnet. To avoid thermal damage to the magnet during processing, WAWJ (Wet Abrasive Waterjet) cutting was employed on sintered NdFeB. Experimental results indicate that at an ambient temperature of 4.5 °C, the maximum cutting temperature remains below 50 °C, with an average cutting temperature below 25 °C. No heat-affected zones or oxidation layers are exhibited on the cutting surface of the magnet. Jet pressure is identified as the primary factor influencing the maximum cutting temperature, accounting for 96.13 %. With jet pressure increasing from 200 MPa to 280 MPa, the maximum cutting temperature rises from 38.7 °C to 47.9 °C. Furthermore, to validate the necessity of low-temperature cutting for NdFeB magnets, WEDM (Wire Electrical Discharge Machining) and laser cutting were employed on sintered NdFeB magnets. The cutting surfaces of both methods exhibit defects such as cracks, craters, and melting. Compared to the original magnet surface, no significant changes in elemental content were observed on the WAWJ-cut surface. Under high-temperature conditions, the oxidation rate increased, leading to a 18.9 % and 19.8 % increase in oxygen content on the WEDM and laser machined surfaces, respectively. Some neodymium (Nd) and iron (Fe) elements exist in the form of oxides such as FeO and Nd2O3, resulting in loss of magnetism. Moreover, the presence of oxides reduces the continuity of magnetic phases, adversely affecting the magnetic properties of the magnet.

Thermally Stable High-Entropy Layered Double Hydroxides for Advanced Catalysis.

Layered double hydroxides (LDHs), especially high-entropy LDHs (HE-LDHs), have gained increasing attention. However, HE-LDHs often possess poor thermal stability, restricting their applications in thermo-catalysis. Herein, a novel complexing nucleation method is proposed for engineering HE-LDHs with enhanced thermal stability. This approach precisely controls the nucleation of metal ions with different solubility products, achieving homogeneous nucleation and effectively mitigating phase segregation and transformation at elevated temperatures. The prepared HE-LDH sample demonstrated exceptional thermal stability at temperatures up to 300°C, outperforming all previously reported LDHs. Importantly, these HE-LDHs preserve both Lewis and Brønsted acidic sites, enabling the 100% removal of aromatic sulfides and alkaline nitrogen compounds from fuel oils in thermo-catalytic oxidation reactions. Experimental and characterization findings reveal that the metal-hydroxide bonds in the prepared HE-LDHs are strengthened by associated hydroxyl groups, inducing negative thermal expansion and augmenting the presence of acidic sites, thereby ensuring structural stability and enhancing catalytic activity. This study not only proposes a strategy for engineering HE-LDHs with remarkable thermal stability but also highlights potential applications of LDHs in thermo-catalysis.

Cationic Covalent Organic Framework-Modified Polypropylene Separator for High-Performance Lithium Metal Batteries.

As an important component of lithium batteries, the wettability and thermal stability of the separator play a significant role in cell performance. Despite the availability of numerous commercial separators, issues such as low ion selectivity and poor thermal stability continue to limit the efficiency and reliability of the batteries. Herein, two cationic covalent organic frameworks (Br-COF and TFSI-COF) with abundant imidazole cationic groups were designed to modify commercial polypropylene (PP) separators. The strong lithium-ion affinity of the cationic COF enables the effective dissociation of lithium salt ion clusters, simplifying the solvent structure of lithium ions to promote lithium ions transport. Additionally, solvent anions can be anchored to the cationic COF by electrostatic interactions, reducing side reactions on the lithium metal anode surface to form a favorable SEI layer, which can effectively inhibit the growth of lithium dendrites. The rapid dissociation of anions in lithium salts with some organic solvents and cationic COFs was revealed by a molecular dynamics simulation. A LiF-rich SEI layer on the lithium metal anode surface was formed, which can speed up Li+ transport at interfaces, leading to consistent lithium deposition and outstanding battery performance. The ordered porous structure of the cationic COF provides interconnected and continuous channels, improving the wettability between the liquid electrolyte and separators, which is conducive to ion transport. When paired with a LiFePO4 cathode and electrolyte (1.0 M LiTFSI in DEC: EC: DMC = 1:1:1), the LiFePO4/TFSI-COF@PP/Li cell demonstrates a prominent cycling capacity of 148.0 mAh g-1 at 0.5 C with a Coulombic efficiency of 98.0% in the first cycle, and the capacity retention is 82.0% after 100 cycles, showing good cycling stability. Thus, this investigation provides inspiration for the expansion of cationic COF-modified separators for next-generation lithium metal batteries.

A bacterial cellulose composite separator with high thermal stability and flame retardancy for high-performance lithium ion batteries

Separators play a crucial role in enhancing the safety of lithium-ion batteries (LIBs); however, commercial polyolefin separators exhibit poor thermal stability and are flammable. This study investigates the use of green, environmentally friendly, and renewable bacterial cellulose as a substrate for developing a composite separator (BHM/5). The BHM/5 separator, comprising bacterial cellulose, an inorganic mineral nano-hydroxyapatite (HAP) and flame-retardant melamine polyphosphate (MPP), is fabricated via freeze drying and high-temperature pressing. The developed composite separator demonstrates superior thermal stability and excellent flame retardancy compared with commercial polyolefin separators while maintaining structural integrity at 200℃ and exhibiting self-extinguishing properties after ignition. Furthermore, the BHM/5 separator exhibits a high porosity of 74 % and a substantial electrolyte uptake of 459 %, achieving an ion conductivity of 1.44 mS/cm. As a result, the cell of the LiFePO4-Li system assembled demonstrates an initial discharge capacity of 131.35 mAh·g−1 at a current density of 1C and a capacity retention of 95.4 % after 150 cycles.

Constructing Ultraviolet Nonlinear Optical Crystals with Superior Thermal Stability Based on Organic π-Conjugated [HCOO] Groups.

In recent years, more and more organic π-conjugated moieties have been screened out to create excellent ultraviolet (UV) and deep-UV nonlinear optical (NLO) crystal materials. However, NLO crystals with organic groups usually exhibit poor thermal stability compared with those of traditional inorganic NLO materials. Herein, the organic group [HCOO], which is similar to traditional planar trigonal π-conjugated anionic groups, was employed to successfully build three UV NLO crystals RE(HCOO)3 (RE = Eu, Gd, and Dy) and two centrosymmetric compounds RE(HCOO)2(OH) (RE = Eu, and Gd) with superior thermal stability. Their structures and properties were further studied and characterized, especially the structure evolutions between noncentrosymmetric RE(HCOO)3 (RE = Eu, Gd, and Dy) and centrosymmetric RE(HCOO)2(OH) (RE = Eu, and Gd), as well as the NLO properties of the three crystals RE(HCOO)3 (RE = Eu, Gd, and Dy).

A facile strategy for preparing low dielectric polybutadienes with ultra-low dielectric loss and enhanced thermal stability

With the rapid development of high speed and high frequency communication, organic low dielectric (low-k) materials with both ultra-low dielectric constant (Dk) and ultra-low dielectric loss (Df) are urgently required to ensure signal transmission speed and reliability. 1,2-polybutadiene (1,2-PB) is renowned for its excellent dielectric properties, making it used in high-frequency printed circuit boards (PCBs). However, its poor thermal stability and mechanical properties hinder its application which requires persistent stability. To address this issue, a series of thermal-crosslinkable benzocyclobutene (BCB)-modified PBs were synthesized through a hydrosilylation reaction. These cured PBs exhibited significantly enhanced thermal stability with the glass transition temperature (Tg) exceeding 400 °C. In particular, they displayed ultra-low Dk (2.32–2.41) and ultra-low Df (<0.001). It was found that the properties of cured PBs were related to BCB loadings. Among the cured polymers, PB-g-B30 demonstrated the optimal dielectric properties with a Dk of 2.34 and a Df of 3.6 × 10−4. Subsequently, a PB-g-B30/glass fiber laminate was fabricated, exhibiting superior dielectric and comprehensive properties when compared to commercial low-k laminates. This study provides a facile method to develop PBs with ultra-low Dk and Df and enhanced thermal stability. The outstanding comprehensive properties indicate their potential as low-k materials in high-frequency communication applications.

Taming of Triazole, Tetrazole, and Azido Groups: Nitrogen-Rich Energetic Materials with High Thermal Stabilities.

Nitrogen-rich energetic materials are of interest due to their potential use as high-energy-density materials in various applications. However, most compounds with a high nitrogen content show poor thermal stabilities, which may limit their use in certain applications. In pursuit of nitrogen-rich energetic materials, this study presents the synthesis and characterization of two nitrogen rich energetic compounds, namely 3-azido-1-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (3, C3H3N11, N%: 79.78) and (E)-1,2-bis(3-azido-1-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-yl) diazene (7, C6H2N22, N%: 80.62). Compounds 3 and 7 have high thermal stabilities of 216 and 221 °C, respectively, making them the most thermally stable among metal-free primary explosives. Additionally, they show good energetic performance (vD: 8345 m s-1; P: 25.17 GPa; vD: 8275 m s-1; P: 25.57 GPa), making them potential candidates for metal-free high energy primary explosive. The energetic salts of 3 and 7 were also investigated. Among them, hydrazinium salt 11 displays better energetic performance (vD: 9089 m s-1; P: 30.55 GPa), which was on par with those of cyclotetramethylene tetranitramine (HMX). This research contributes to the exploration of nitrogen-rich energetic materials with potential applications in various fields.

Full-scale experimental study on tribological performance of FPBs for highway bridges with various solid lubricants under fast loading

Friction pendulum bearings (FPBs) have proven to be effective for the seismic isolation of highway bridges. Previous studies often employed scaled model shaking table tests to investigate dynamic responses of the structures or quasi-static tests to assess the hysteretic performance of FPBs. However, it is noteworthy that the stress on the friction surface is reduced due to the size effect in scaled model in shaking table tests, while quasi-static tests of prototype bearings cannot simulate the sliding velocity experienced during seismic events, which is a sensitive parameter for the performance of FPBs with solid lubricant plates. Research on the performance of full-scale FPBs under fast frictional loading is very limited. This paper addresses this knowledge gap by studying the velocity demand for a highway bridge with FPBs and conducting fast sliding performance tests using full-scale FPBs. The results indicate that under a 0.2 g PGA earthquake, the velocity demand for FPBs can reach 0.5 m/s. Through testing full-scale FPBs at various loading speeds, it was found that solid lubricant plates by UHMWPE material exhibit poor thermal stability during wear tests, solid lubricant plates by PTFE material lack sufficient tangential tear strength under fast loading, and solid lubricant plates by PET material show good wear resistance but have a high breakaway force and levered maximum force during the running-in stage. Subsequently, this study developed ultra-high performance friction plate (UHPF) as the solid lubricant for FPBs, achieving ideal hysteretic performance under fast loading. The full-scale FPB specimens in this paper are the ones manufactured for the continuous beam bridges in the Shenzhen-Zhongshan Sea-crossing Link project in China. The dimensions of the bearing, axial load, and loading speed is much more stringent than those in previous FPB tests, providing results that are highly important for engineering applications.

Preparation and properties of fluorinated VAc-VeoVa10 latex emulsified with allyl nonyl phenoxy propyl alcohol polyoxyethylene ether ammonium sulphate

Purpose The traditional VeoVa10-VAc copolymer latex, which prepared via the emulsion polymerization of the mixed monomers of VAc and VeoVa10, has the poor water resistance and thermal stability because of the migration of the conventional emulsifier molecules and the low bond energy of C-C bond. The purpose of this work is that the fluorinated monomer is used to modify the latex. The film of the resultant latex has the C-F bond with high bond energy and low surface energy, which can effectively improve the heat resistance and water resistance of the resultant film. In addition, the reactive emulsifier is used to replace the conventional emulsifier. The drawbacks of the conventional emulsifier molecules migrate and desorb can be avoided when the polymer latex is stored, thereby also improving the water resistance. Design/methodology/approach The modified VAc-VeoVa10 latex has been successfully synthesized via the semi-continuous seeded emulsion polymerization, which VAc and VeoVa10 is used as the main monomers and HFMA was used as the functional monomer. KPS and reactive surfactants of SE-10 were used as the initiator and emulsifier, respectively. The structure of resultant latex film was characterized by Fourier transform infrared spectroscopy (FTIR). The latex films were tested by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA). The particle size and its distribution of the latex were measured by the nano particle size analyzer. Findings The factors that had an influence on the properties of the latex and the film were investigated in detail. The stability of the resultant latex is good. The average particles of the latex and its distribution are small and uniform, respectively. In comparison with the conventional latex film, the thermal stability and hydrophobicity of the resultant latex film are improved obviously. Practical implications The resultant latex can be used in both the waterborne interior and exterior wall coatings, pickering stabilized waterborne polymer dispersions, polymer powders, environmentally friendly polymer-modified waterproof mortar and other fields, which can be satisfied with the high demand of thermal stability and hydrophobicity. Originality/value The modification of poly (VAc-VeoVa10) by reactive surfactant and fluorinated monomer is seldom reported. In this study, the fluorinated poly (VAC-VeoVa) latex is prepared via the reactive surfactants, which VAc and VeoVa10 is used as the main monomers and hexafluorobutyl methacrylate is used as the functional monomer. Potassium persulfate (KPS) and allyl nonyl phenoxy propyl alcohol polyoxyethylene ether ammonium sulfate are used as the initiator and emulsifier, respectively.

Маститы – проблема безопасности, качества и сыропригодности молока сырого

Bovine mastitis is a common hygiene-related issue in milk production. It increases the somatic cell count in milk. Somatic cell count is an important indirect indicator of milk quality. Somatic cells include those of udder and blood. Normally, one healthy udder lobe secretes ≤ 500,000 somatic cells per 1 cm3 milk. In the presence of pathogenic bacteria, the same amount indicates a latent infection. Inflammatory processes in the udder include impaired secretion and mastitis. They increase the number of leukocytes and other blood cells in the total somatic cell count, which means that the milk came from sick cows. Raw milk for cheese production must contain ≤ 4×105 cells per 1 cm3. Mastitis, or garget milk is not suitable for cheese production. Staphylococcus aureus is the most common causative agent of staphylococcal mastitis in cows. Coagulase-positive staphylococci are responsible for 30-50% cases of infectious mastitis. They pose great risks for bulk-formed cheeses. Mastitis affects milk processing, taste, and storage capacity. It is high in chlorides and low in lactose, which gives it a flat and salty-bitter taste. If somatic cell count exceeds 5×105 cells per 1 cm3, the resulting milk has poor thermal stability. As the content of somatic cells in milk increases, so does the rennet coagulation time: fat goes into whey and moisture in curd increases, which eventually reduces cheese yield.

Thermally-stable and flame-retardant metal-organic framework-based separator for high-performance lithium-ion batteries

Safety hazards hinder the development of lithium-ion batteries (LIBs), in which the failure of separator is a key point. However, commercial polyolefin separators display poor thermal stability and flame-retardant property. Aramid nanofiber (ANF) is a promising material for safer separators in batteries due to its excellent thermal stability and remarkable flame retardancy, but the pure ANF separator often shows low ionic conductivity because of the tightly packed fibers. Metal-organic framework (MOF) is a promising candidate for increasing the porosity and ionic conductivity of ANF separator due to its ultrahigh porosity and ultrahigh specific area. Herein, a thermally-stable and high-performance composite separator is fabricated by combining MOF pore-forming agent and ANF network skeleton. The MOF/ANF1composite separator with 10 wt% ANF shows excellent thermal-stability (melting-point above 300 °C and decomposition temperature above 500 °C) and remarkable flame-retardant property. And it exhibits high ionic-conductivity of 1.01 mS·cm−1, contributed to the superior long-term cycling performance of the coin cell with the capacity of 147.3 mAh·g−1 after 200 cycles at 1 C, almost 25.4 % higher than that of the coin cell with PP separator for LIBs. The strategy of this research provides new ideas for the design of high-safety LIBs.

Construction of Cyclodextrin-Based Covalent Organic Frameworks for Efficient Encapsulation of Menthol.

The application of flavoring ingredients like menthol in the food industry is hindered by their high volatility and poor thermal stability, which lead to significant losses during processing and storage. Encapsulation of flavors into porous materials to obtain inclusion complexes (ICs) has proved to be an efficient strategy. In the present study, we synthesized a series of relatively food-safe three-dimensional anionic cyclodextrin-based covalent organic frameworks (CD-COFs) with spiroborate linkages using a facile microwave-assisted method. The high surface area and newly formed cavitied of COFs significantly enhanced the encapsulation efficiency of menthol compared to native CD materials. Our findings revealed that γ-CD-COF-Li, with Li+ as the counterion, achieved superior encapsulation efficiency of 25.9%, outperforming γ-CD-COF-Na, γ-CD-COF-K and α-CD-COF-Li under the same conditions. Thermal stability measurements show that the menthol/γ-CD-COF-Li-ICs effectively stabilize menthol against heat evaporation at elevated temperatures due to the strengthened interaction between menthol and γ-CD-COF-Li. The promising results of this research suggest that rapid advancements in COF technology will provide new opportunities for enhancing the stability of flavoring ingredients in the food industry.

Lignin-containing cellulose nanocrystals enhanced electrospun polylactic acid-based nanofibrous mats: Strengthen and toughen

Biodegradable polylactic acid (PLA) nanofibrous mats prepared by electrospinning serve as suitable packaging materials. However, their practical applications are limited by their weak mechanical properties, poor thermal stability, and high cost. In this study, green and low-cost lignin-containing cellulose nanocrystals (LCNCs) with different lignin contents were developed and employed as reinforced materials to synergistically enhance the thermal, mechanical, and hydrophobic properties of PLA electrospun nanofibrous mats. The presence of moderate lignin improved the interfacial compatibility between the LCNCs and PLA, resulting in excellent mechanical properties of the nanofibrous mats. Compared to pure PLA mats, the tensile strength of the composites reached up to 21.0 MPa, representing a 6.6-fold increase. Its toughness was synchronously enhanced by 16 times, reaching a maximum of 3.6 MJ/m3. The maximum decomposition temperature of PLA/LCNCs electrospun nanofibrous mats increased from 339 °C to 365 °C. Furthermore, the increase in lignin in the LCNCs positively contributed to improving the hydrophobicity of the PLA/LCNCs electrospun nanofibrous mats. This bio-based strategy of LCNCs employed in the enhancement of fully bio-based PLA nanofibrous mats offers a viable approach for the advancement of packaging films.

Air-stable and UV-NIR broadband photodetectors utilizing graphene and core/shell quantum dots hybrid heterostructure

Photodetectors based on PbSe quantum dots (QDs) are commonly used for light detection in the near-infrared (NIR) region. Nevertheless, the performance of photodetectors based on PbSe QDs is constrained by ineffective carrier transfer and poor photo and thermal stabilities. Herein, a promising strategy that harnesses PbSe/PbS core/shell QDs structures is developed and demonstrated to enhance the long-term stability of photodetectors, further combining with graphene to form hybrid heterojunctions that effectively promote carrier transfer. As a result, the devices exhibit a broad photoresponse to the incident light at range of 365–1250 nm, and also possess a high photosensitivity of 1.5 × 104 A/W and a high detectivity of 4.0 × 1013 Jones. Moreover, the lifetime of graphene-PbSe/PbS core/shell QDs hybrid photodetector was 9 times greater than that of uncoated QDs devices. The enormous boost might be attributed to the passivation and protection provided by the core–shell structure, and graphene’s efficient extraction of charge carriers.

Preparation of PU/SiO2 composite shell microencapsulated phase change materials with high thermal stability and thermal conductivity

To address the issues of poor thermal stability and thermal conductivity in polyurethane (PU) shell microencapsulated phase change materials (MEPCMs), this study prepared PU/SiO2-MEPCMs using an interfacial polymerization method combined with electrostatic self-assembly technology. First, the PU shell was synthesized via an interfacial polymerization reaction between isophorone diisocyanate (IPDI) and triethanolamine (TEA). Subsequently, the hydrolyzed product of tetraethyl orthosilicate (TEOS), monosilicic acid (Si (OH)4), was adsorbed onto the PU shell surface using electrostatic self-assembly technology and reacted with the –NCO groups to form an SiO2 shell. The effects of the PU/SiO2 composite shell on the surface morphology, chemical structure, compactness, thermal stability, phase transition performance, thermal conductivity, and thermal cycling stability of MEPCMs were investigated. The results showed that the formation of the PU/SiO2 composite shell significantly improved the thermal stability, compactness, thermal conductivity, and cyclic stability of MEPCMs. After continuous treatment at 150°C for 120 min, the leakage rate of the core material decreased from 12.13 % to 3.74 %, and the heat-resistant temperature (T95 %) increased by 30°C. Even after 1000 thermal cycles, MEPCMs still exhibited excellent heat storage performance. Additionally, even under high temperature conditions of 257°C (where pure butyl stearate completely decomposes), the PU/SiO2-MEPCMs still maintained a stable core-shell structure. The introduction of the SiO2 shell greatly enhanced the thermal conductivity of MEPCMs, aligning the phase change temperature more closely with that of the core material and effectively reducing the supercooling phenomenon. Furthermore, the stable energy storage system formed by MEPCMs on the finished fabric surface can endow it with excellent temperature regulation functionality.

Li1.4Al0.4Ti1.6(PO4)3 coating surface modification enables improved electrochemical performance of LiNi0.83Co0.11Mn0.06O2 cathode

High-nickel ternary active materials with LiNi0.83Co0.11Mn0.06O2 (NCM83) have attracted extensive attention from researchers because of their exceptional performance and competitive pricing. Nevertheless, the actual large-scale uses of this material are restricted due to its limited lithium vacancies, residual lithium on the surface, and poor thermal stability. To improve the electrochemical performance of NCM83, an effective strategy for coating high ionic conductors of Li1.4Al0.4Ti1.6(PO4)3 (LATP) on NCM83 has been proposed. The uniform coatings of LATP are prepared by a wet coating process, which efficiently protects NCM83 from electrolyte attack, reduces internal stress, and improves the material’s thermal stability. Consequently, the cycle stability and thermal stability of the coated cathodes are significantly enhanced. Typically, 1 wt% LATP coating delivers a higher discharge specific capacity of 179.3 mAh g−1 at 2 C. The capacity retention rate is 69.67 % after 300 cycles at 1 C, higher than NCM83 (capacity retention rate of only 61.27 %). This study presents a new direction for researching high-nickel ternary cathode materials.

Preparation, microstructure and interfacial architecture of Ni-coated Ti3C2Tx reinforced Al6061 composites

Aluminum matrix composites (AMCs) reinforced by Ti3C2Tx are receiving increasing attention. However, the key constraints to its application breadth are the poor thermal stability and its poor interfacial bonding with aluminum (Al). In this paper, the surface modification of Ti3C2Tx is carried out by chemical Ni coating, and the effects of such reinforcement on the microstructure and interfacial architecture, as well as the mechanical properties of the Al6061 composites before and after Ni-coated are compared. The results show that Ni-coated Ti3C2Tx improves its dispersion in the Al melts and blocks the interfacial reaction between Al and Ti3C2Tx. HRTEM analysis shows that the dense Ni nanoparticles on the surface of Ti3C2Tx optimize its interfacial structure with Al. The mismatch of (102)Al3Ni//(1−11)Al is 4.3 %, indicating that the Al6061–2.5 wt% Ti3C2Tx@Ni (AT2.5@Ni) composites are strengthened by the form of Al3Ni-Al interfacial coherence. The yield strength, tensile strength, and elongation of AT2.5@Ni composites are 122.1 MPa, 223.4 MPa, and 5.2 %, which are 53.0 %, 57.9 %, and 2.0 % higher than that of Al6061 matrix, respectively. The better mechanical properties are mainly attributed to the strong Ti3C2Tx-Ni-Al3Ni-Al interfacial architecture formed in the composites, resulting in the effective load transfer from matrix to Ti3C2Tx.

Extraction, characterization, and neuroprotective effects of polysaccharides the stems of Panax ginseng C. A. Meyer by three different solvents (water, acid, alkali)

The purpose of this study was to optimize the extraction process of polysaccharides from the stems of Panax ginseng C. A. Meyer using different solvents (water, acid and alkali), and investigate their protective effects on PC12 cells against Amyloid-β1–42 (Aβ1–42)-induced cell apoptosis. Three polysaccharides (W-GSP, Ac-GSP and Al-GSP) were prepared and optimized: liquid to material ratio 27:1 mL/g, extraction temperature 89°C, extraction time 2.9 h and 0.3 mol/L HCl/NaOH. The results of characterization indicated that the monosaccharides of W-GSP (703.80 kDa), Ac-GSP (641.38 kDa) and Al-GSP (457.04 kDa) all composed mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, xylose and arabinose with different molar ratios. Interestingly, W-GSP possessed a lower uronic acid, higher molecular weight, rougher surface and poorer thermal stability, whereby W-GSP exhibited a protective effect against Aβ1–42-induced apoptosis in PC12 cells by mediating the JNK signaling pathway, restoring the mitochondrial membrane potential and reducing intracellular ROS levels. This study should be provided the theoretical basis for the study and exploitation of polysaccharides from the stems of Panax ginseng C. A. Meyer.

Fish Gelatin-Based Flexible and Self-Healing Hydrogel Modified by Fe2(SO4)3.

The application of fish gelatin (FG) is limited due to its poor mechanical properties and thermal stability, both of which could be significantly improved by gellan gum (GG) found in previous research. However, the FG/GG composite hydrogel was brittle and easily damaged by external forces. It was found that the composite hydrogel with Fe2(SO4)3 showed good flexibility and self-healing properties in the pre-experiment. Thus, the synergistic effect of FG, GG and Fe2(SO4)3 on the mechanical properties of the composite hydrogel was investigated in this study. According to one-way experiments, response surface tests and Texture Profile Analysis, it was found that under the optimum condition of FG concentration 186.443 g/L, GG concentration 8.666 g/L and Fe2(SO4)3 concentration 56.503 g/L, the springiness of the composite cylindrical hydrogel with the height of 25 mm formed in 25 mL beakers (bottom diameter 30 mm) was 7.602 mm. Determination of the rheological properties, compression performance, adhesive performance and self-healing properties showed that the composite hydrogel had good thermal stability, flexibility and self-healing properties with good adhesion, skin compliance and compressive strength, and it was easy to remove. The composite hydrogel showed strong antimicrobial activity against A. salmonicida and V. parahaemolyticus. All hydrogels showed a uniform and porous structure. The 3D structure of the composite hydrogel was much looser and more porous than the pure FG hydrogel. The flexible and self-healing composite hydrogel with some antimicrobial activity is suitable for the development of medical dressings, which broadens the applications of the composite hydrogel.