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Polyimide (PI) foam exhibits excellent high-temperature resistance and outstanding physical and chemical stability, making it an ideal matrix for absorbing materials. However, the growing demand for absorbing materials that can serve as load-bearing components has revealed that existing polyimide composite foams often fall short of practical application requirements due to their low mechanical properties. The study employed a simple foaming method using isocyanate-based polyimide as the foam base under a 0.2 MPa atm. Multi-walled carbon nanotubes (MWCNTs) and carbonyl iron (CI) powder were added sequentially to the precursor solution. Under the filling parameters of 2.0 % MWCNTs and 10 % CI powder, the compressive strength of polyimide composite foam reaches 16.2 MPa and exhibits excellent microwave absorption properties, with a minimum reflection loss (RLmin) of −62.51 dB and an effective absorption bandwidth (EAB) of 7.86 GHz. Additionally, the prepared composite foam has potential infrared stealth capability. This work offers new insights for rapid and low-cost manufacturing of high-strength absorbing foam.

ABSTRACTCalonectriaspecies are soil-borne and widely distributed in tropical and subtropical regions around the world. The species in this genus include many important plant pathogens that cause serious diseases to economically important crops and forest trees. Previous research results indicated that the leaf blight and cutting rot caused by Calonectriaspecies caused big losses to the Eucalyptusindustry in southern China, and large number of Calonectriaspecies identified in China have been collected from soil in Eucalyptusplantations. In this study, Calonectriasamples were isolated from soils close to Eucalyptusplantations in Guangdong Province, southern China. These isolates were identified by DNA sequence analyses based on the calmodulin (cmdA), histone H3 (his3), translation elongation factor 1-alpha (tef1), and β-tubulin (tub2) gene regions, and combined with morphological characteristics. One novel species of Calonectriawas identified and described, named Calonectria xianrensis, which resides in the Prolate Group. Results in this study suggest that more species of Calonectriamay be distributed in soils in China.

Diseases caused by species of Calonectria (Ca.)represent a serious threat to the growth and sustainability of Eucalyptusplantations in China. Symptoms caused by these fungi mainly include leaf blight on trees in plantations and rotting of stems and leaves in nurseries. Extensive surveys have recently been conducted where Calonectriaspecies were collected in Eucalyptusplantations and nurseries in the FuJian, GuangDong, GuangXi, and YunNan Provinces of South China. Additional isolates were baited from soil samples in the Hong Kong Region. The aim of this study was to identify the 115 Calonectriaisolates obtained using comparisons of DNA sequence data for the ß-tubulin (tub2), calmodulin (cmdA), histone H3 (his3)and partial translation elongation factor-1 a (tefl)gene regions as well as their morphological features. Seven known species were identified, including Calonectria arbusta, Ca. asiatica, Ca. chinensis, Ca. eucalypti, Ca. hongkongensis, Ca. mossambicensisand Ca. pentaseptata.In addition, six novel taxa were collected and are described here as Ca. aciculata, Ca. honghensis, Ca. lantauensis, Ca. pseudoturangicola, Ca. pseudoyunnanensis, and Ca. yunnanensisspp. nov. Overall, the results reflect a high diversity of Calonectriaspecies in China.

Interconnected Ni(OH)2nanoflakes and polyether amine (PEA) were deposited on carbon fiber tows via a facial and effective process of chemical bath deposition and dip coating. Based on this, a win–win benefit of simultaneously improvements in interfacial shear strength (IFSS) of carbon fiber/epoxy composites and the electrochemical activity has been achieved. Compared with CF and CF-Ni(OH)2composites, the IFSS of CF-Ni(OH)2-PEA/epoxy composite respectively increased 7.9% and 45.4%, which was put down to the covalent bonding of Ni(OH)2-PEA coating with fiber and epoxy matrix, as well as the effective stress transfer by the uniform honeycomb structure of Ni(OH)2. In aqueous KOH electrolyte, the CF-Ni(OH)2-PEA electrode presented the maximum specific capacitance of 689.98F·g−1at 5 mV·s−1, 572.28F·g−1at a current density of 0.5 A·g−1due to the strong adhesion of carbon fiber with Ni(OH)2by PEA, the reservation of the three-dimensional hollow honeycomb structure of Ni(OH)2for easy ion-transport and –NH2functional groups from PEA for providing more active sites. The excellent performance of CF-Ni(OH)2-PEA reinforcement demonstrates its promising potential for application in high performance composites with integrated structure and function, which shows great advantages in various fields of aerospace, energy, electronics, automobile, civil engineering, sports, etc.

A finite element formulation and the solution of a set of nonlinear coupled heat and mass transfer equations for a two-phase system with a moving evaporation interface is presented. The interface condition takes into account the moisture transfer balance at the moving boundary. The finite element results were compared with existing results for a single phase system for model validation. In the two-phase system, the movement of evaporation front has an appreciable effect on the temperature and moisture distribution inside the porous medium during drying. The effect of the nondimensional heat of vapourization parameter γ on the evaporation front, temperature and moisture distribution in porous medium was studied. The higher the value of γ, the slower is the movement of the evaporation front. The temperature decreased and the moisture content increased as the nondimensional vapourization parameter γ increased. This model has potential applications in studying the heat and mass transfer characteristics in food and biomaterials.

In recent years, Fe–Mn–Al–C steel has been widely regarded as a promising lightweight material due to its excellent specific strength and good balance of strength and toughness. However, the performance of welded joints is crucial for the application of Fe–Mn–Al–C low-density steel. This paper aims to study the effect of different solution treatment times on the mechanical properties and microstructure of tungsten inert gas (TIG) welding of Fe-29Mn-9Al-0.9C low-density steel. After solution treatment, the phase types of the weld change and the granular ferrite transforms into austenite. Electron backscattered diffraction (EBSD) results show that with the increase of solution treatment time, dislocation density decreases, recrystallized grains grow, and the texture changes from uniform distribution to cubic texture again. It is concluded that in the early stage of recrystallization, dislocation walls are formed due to dislocation slip, which impedes dislocation movement in the process of stretching and thus improves the tensile strength. By controlling the time of solution treatment, the maximum tensile strength can be increased to 845.05MPa and the maximum elongation can be increased to 38.21%, which are all higher than for the welded joints without solution treatment.

A single-ion conductor polymer electrolyte was prepared and the effects of the ratio of isophthalic acid (IPA) to 4, 4'-diphenyl ether dicarboxylic acid (DPE) on the structure and electrochemical properties have been investigated. Results show that all the lithium sulfonated polyoxadiazoles (Li-SPODs) have excellent thermal stability (510 degC). The ionic conductivity of the Li-SPOD is 7.2 x 10[?]4 S cm[?]1 at room temperature when the IPA/DPE ratio is 6/4. A high Coulombic efficiency of 99.1% for the LiFePO4/6/4 li-SPOD SPEs/Li half-cell could be achieved with a capacity retention of 90.63% at a current density of 0.1 C after 25 cycles.

A single-ion conductor polymer electrolyte was prepared and the effects of the ratio of isophthalic acid (IPA) to 4, 4’-diphenyl ether dicarboxylic acid (DPE) on the structure and electrochemical properties have been investigated. Results show that all the lithium sulfonated polyoxadiazoles (Li-SPODs) have excellent thermal stability (510 °C). The ionic conductivity of the Li-SPOD is 7.2 × 10−4S cm−1at room temperature when the IPA/DPE ratio is 6/4. A high Coulombic efficiency of 99.1% for the LiFePO4/6/4 li-SPOD SPEs/Li half-cell could be achieved with a capacity retention of 90.63% at a current density of 0.1 C after 25 cycles.