Investigating the Impact Behavior of Carbon Fiber/Polymethacrylimide (PMI) Foam Sandwich Composites for Personal Protective Equipment.

To improve the shock resistance of personal protective equipment and reduce casualties due to shock wave accidents, this study prepared four types of carbon fiber/polymethacrylimide (PMI) foam sandwich panels with different face/back layer thicknesses and core layer densities and subjected them to quasi-static compression, low-speed impact, high-speed impact, and non-destructive tests. The mechanical properties and energy absorption capacities of the impact-resistant panels, featuring ceramic/ultra-high molecular-weight polyethylene (UHMWPE) and carbon fiber/PMI foam structures, were evaluated and compared, and the feasibility of using the latter as a raw material for personal impact-resistant equipment was also evaluated. For the PMI sandwich panel with a constant total thickness, increasing the core layer density and face/back layer thickness enhanced the energy absorption capacity, and increased the peak stress of the face layer. Under a constant strain, the energy absorption value of all specimens increased with increasing impact speed. When a 10 kg hammer impacted the specimen surface at a speed of 1.5 m/s, the foam sandwich panels retained better integrity than the ceramic/UHMWPE panel. The results showed that the carbon fiber/PMI foam sandwich panels were suitable for applications that require the flexible movement of the wearer under shock waves, and provide an experimental basis for designing impact-resistant equipment with low weight, high strength, and high energy absorption capacities.

Plant immune receptors interact with hemibiotrophic pathogens to activate plant immunity.

Phytopathogens pose a devastating threat to the productivity and yield of crops by causing destructive plant diseases in natural and agricultural environments. Hemibiotrophic pathogens have a variable-length biotrophic phase before turning to necrosis and are among the most invasive plant pathogens. Plant resistance to hemibiotrophic pathogens relies mainly on the activation of innate immune responses. These responses are typically initiated after the plant plasma membrane and various plant immune receptors detect immunogenic signals associated with pathogen infection. Hemibiotrophic pathogens evade pathogen-triggered immunity by masking themselves in an arms race while also enhancing or manipulating other receptors to promote virulence. However, our understanding of plant immune defenses against hemibiotrophic pathogens is highly limited due to the intricate infection mechanisms. In this review, we summarize the strategies that different hemibiotrophic pathogens interact with host immune receptors to activate plant immunity. We also discuss the significant role of the plasma membrane in plant immune responses, as well as the current obstacles and potential future research directions in this field. This will enable a more comprehensive understanding of the pathogenicity of hemibiotrophic pathogens and how distinct plant immune receptors oppose them, delivering valuable data for the prevention and management of plant diseases.

Enhanced Enzymatic Performance of ß-Mannanase Immobilized on Calcium Alginate Beads for the Generation of Mannan Oligosaccharides.

Mannan oligosaccharides (MOSs) are excellent prebiotics that are usually obtained via the enzymatic hydrolysis of mannan. In order to reduce the cost of preparing MOSs, immobilized enzymes that demonstrate good performance, require simple preparation, and are safe, inexpensive, and reusable must be developed urgently. In this study, ß-mannanase was immobilized on calcium alginate (CaAlg). Under the optimal conditions of 320 U enzyme addition, 1.6% sodium alginate, 2% CaCl2, and 1 h of immobilization time, the immobilization yield reached 68.3%. The optimum temperature and pH for the immobilized ß-mannanase (Man-CaAlg) were 75 °C and 6.0, respectively. The Man-CaAlg exhibited better thermal stability, a high degree of pH stability, and less substrate affinity than free ß-mannanase. The Man-CaAlg could be reused eight times and retained 70.34% of its activity; additionally, the Man-CaAlg showed 58.17% activity after 30 days of storage. A total of 7.94 mg/mL of MOSs, with 4.94 mg/mL of mannobiose and 3.00 mg/mL of mannotriose, were generated in the oligosaccharide production assay. It is believed that this convenient and safe strategy has great potential in the important field of the use of immobilized ß-mannanase for the production of mannan oligosaccharides.

Rational Design of Fluorinated Phthalonitrile/Hollow Glass Microsphere Composite with Low Dielectric Constant and Excellent Heat Resistance for Microelectronic Packaging.

High-performance composites with a resin matrix are urgently required for electronic packaging due to their low dielectric constant, outstanding high temperature resistance, excellent corrosion resistance, light weight and easy molding. In this work, hollow-glass-microsphere (HGM)-filled fluorinated-phthalonitrile (PBDP) composites, with filler contents ranging from 0 to 35.0 vol.%, were prepared in order to modify the dielectric properties of the phthalonitrile. Scanning electron microscopy (SEM) observations indicate that the modified HGM particles were uniformly dispersed in the matrix. The PBDP/27.5HGM-NH2 composite demonstrates a low dielectric constant of 1.85 at 12 GHz. The 5% thermogravimetric temperature (T5) of composites with silanized HGM filler (481-486 °C) is higher than the minimum packaging-material requirements (450 °C). In addition, the heat-resistance index (THRI) of PBDP/HGM-NH2 composites reached as high as 268 °C. the storage modulus of PBDP/HGM-NH2 composites were significantly increased to 1283 MPa at 400 °C, an increase by 50%, in comparison to that of PBDP phthalonitrile resin (857 MPa). The excellent dielectric and thermal properties of the present composites may pave a way for comprehensive applications in electronic packaging and thermal management for energy systems.

Recent progress on harm, pathogen classification, control and pathogenic molecular mechanism of anthracnose of oil-tea.

Oil tea (Camellia oleifera), mainly used to produce high-quality edible oil, is an important cash crop in China. Anthracnose of oil tea is a considerable factor that limits the yield of tea oil. In order to effectively control the anthracnose of oil tea, researchers have worked hard for many years, and great progress has been made in the research of oil tea anthracnose. For instance, researchers isolated a variety of Colletotrichum spp. from oil tea and found that Colletotrichum fructicola was the most popular pathogen in oil tea. At the same time, a variety of control methods have been explored, such as cultivating resistant varieties, pesticides, and biological control, etc. Furthermore, the research on the molecular pathogenesis of Colletotrichum spp. has also made good progress, such as the elaboration of the transcription factors and effector functions of Colletotrichum spp. The authors summarized the research status of the harm, pathogen types, control, and pathogenic molecular mechanism of oil tea anthracnose in order to provide theoretical support and new technical means for the green prevention and control of oil tea anthracnose.

Selection of potential reference genes for RT-qPCR in the plant pathogenic fungus Colletotrichum fructicola.

Colletotrichum is widespread, and these pathogenic fungi can cause various plant diseases. Studies have shown that Colletotrichum fructicola cause oil-tea (Camellia oleifera) anthracnose and is widely distributed as a dominant fungus in all Ca. oleifera-producing regions. Real-time quantitative PCR(RT-qPCR) is considered the most reliable technique for simultaneously measuring relative gene expression levels in different tissues. Target genes are typically quantified using RT-qPCR to explore gene function, and reliable RT-qPCR results require data normalization using stable reference genes. No studies have reported a suitable reference gene in C. fructicola. This study has eight candidate reference genes (CfCk, CfRpp, CfUce, CfRrp, CfAdrh, CfDd, CfAct, and CfTub) which were selected from C. fructicola-Ca. oleifera transcriptome data and evaluated and sequenced using geNorm, NormFinder, and BestKeeper algorithms. The results showed that CfRrp had better stability in C. fructicola, both during the growth of pure pathogenic fungi and during the invasion of different oil-tea leaves. After normalization with CfRrp, the differentially expressed target genes were similar to the transcriptome. Our work provides suitable reference genes for future studies to quantify target gene expression levels in C. fructicola.

In situ electrochemical investigation of the reaction progress between Zr and a CuCl-SnCl2 mixture in a LiCl-KCl molten salt.

The electrochemical behaviors of CuCl, SnCl2 and a CuCl-SnCl2 mixture were investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). The reduction potentials of Cu(i) and Sn(ii) on CV curves are -0.49 and -0.36 V, respectively, while the reduction potentials of Cu(i)-Sn(ii) in the CuCl-SnCl2 mixture almost overlap. The co-chlorination reaction progress between CuCl-SnCl2 and Zr was also studied by monitoring the concentration changes of Cu(i), Sn(ii) and Zr(iv) ions in situ by CV, SWV and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analyses. The results indicate that during the reaction, the concentration of Zr(iv) ions increases gradually, while those of Cu(i) and Sn(ii) decrease rapidly until they disappear. When the molar ratios of Cu(i) to Sn(ii) are 1 : 1 and 1 : 0.5, the reaction between Cu(i) and Zr is faster but cannot exceed twice that of Sn(ii) and Zr in a short time. When the theoretical product of ZrCl4 is a constant, and with the proportion of CuCl to SnCl2 decreasing from 1 : 0 to 0 : 1, the chlorination reaction time periods increase from 40 to 170 min. Chloride products such as Cu x Sn y , Sn x Zr y , and Cu x Zr y , are formed with different molar ratios. The coupling effect caused by the formation of alloys will promote the chlorination reaction when the ratios of CuCl to SnCl2 are 0.66 : 0.17 and 0.5 : 0.25. The results provide a theoretical basis for the electrolytic refinement of zirconium.

First Report of Colletotrichum fructicola Causing Anthracnose on Camellia yuhsienensis Hu in China.

Camellia yuhsienensis Hu is an endemic species from China, where is the predominant oilseed crop due to its anthracnose resistance (Kuang 2015; J. Li et al. 2020; Nie et al. 2020). In April 2019, anthracnose symptoms were observed on C. yuhsienensis in a plantation in Youxian, Zhuzhou, Hunan Province, China (113.32°E, 26.79°N). It was detected approximately 10% anthracnose incidence in 500 two-year-old plants in a 5000 m2 cultivated area. Diseased leaves showed irregular grayish brown spots with dark brown edges and dark brown undersides. Symptomatic tissues (4 to 5 mm2) were surface-disinfected for 90 s in 75% ethanol, then rinsed twice with sterile water, and finally incubated on PDA (potato dextrose agar) at 28℃ (Jiang et al. 2018). Pure cultures were obtained by the single-spore isolation method. A total of 100 fungal isolates were obtained from 85 symptomatic leaves, from which 81 had similar colony morphology. Colonies on PDA were white, fluffy and cottony, and becoming dark gray after 5 days. The character of the reverse of the colony were similar to that of the upper of the colony, but the color was darker at the same time. The isolates produced a large number of single-celled, hyaline, straight and cylindrical conidia, with 10.35 to 17.58 length × 3.46 to 5.69 µm width (x=13.61 × 4.63 µm, n = 30). The isolates were preliminarily identified as Colletotrichum spp. according to morphological features (Weir et al. 2012). Representative isolate YX2-5-2 was used for molecular identification: internal transcribed spacer (ITS), partial actin (ACT), chitin synthase (CHS-1) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genomic DNA regions were amplified by PCR (Weir et al. 2012). Gene sequences were deposited in GenBank (GenBank accession no. MW398863 for ACT, MW886232 for CHS-1, MW398864 for GAPDH, MW398865 for ITS). BLAST analysis revealed that DNA sequences of YX2-5-2 at the ITS, GAPDH, ACT, and CHS-1 loci showed 100%, 99.25%, 100%, and 99.33% sequence identity, respectively to their corresponding loci in strains ZH6 (GenBank accession no. MT476840.1), ICKP18B4 (LC494274.1), YN17 (MN525804.1), and ICKG4 (LC469131.1) of C. fructicola. A Maximum Likelihood phylogenetic tree based on the combined ACT, CHS-1, ITS and GAPDH sequences revealed that the representative isolate YX2-5-2 clustered with C. fructicola. In addition, the morphological features of YX2-5-2 were similar to C. fructicola which has been reported (Weir et al. 2012). Pathogenicity was tested using isolate YX2-5-2 by inoculating leaves of 2-year-old C. yuhsienensis. Four leaves of each healthy C. yuhsienensis were sprayed with a conidial suspension (105 conidial/mL) of isolate YX2-5-2, and the above steps were repeated three times. Two additional mock-inoculated control plants were sprayed with sterilized liquid potato dextrose medium. The plants were incubated in a greenhouse at 28℃ and 90% humidity with a 12 h photoperiod. Anthracnose-like symptoms were observed 5 days post-inoculation. The control plant tissues remained healthy. C. fructicola was re-isolated on PDA from lesions, and the morphological features were consistent with YX2-5-2, confirming Koch's postulates. To our knowledge, this is the first report of anthracnose of C. yuhsienensis caused by C. fructicola in China. Anthracnose of Camellia. oleifera has been reported for a long time (H. Li et al. 2016). C. yuhsienensis, as a wild relative of C. oleifera (commonly known as tea-oil tree), has been concerned about its resistance to anthracnose. Therefore, the occurrence of C. yuhsienensis anthracnose hindered the control of anthracnose tea-oil tree. This finding will lay the foundation for studying the pathogenesis of anthracnose of tea-oil tree and developing effective prevention methods. References: Jiang, S. Q., et al. 2018. Plant Dis. 102: 674. Kuang, R. 2015. Forest Pest and Disease. Li, H., et al. 2016. PLoS One 11: e0156841. Li, J., et al. 2020. Microorganisms 8: 1385. Nie, Z., et al. 2020. Mitochondrial. DNA. B. 5: 3016. Weir, B. S., et al. 2012. Stud. Mycol. 73: 115.

Adsorption process and mechanism of heavy metal ions by different components of cells, using yeast (Pichia pastoris) and Cu2+ as biosorption models.

Microbial biomass has been recognized as an essential biosorbent to remove heavy metal ions, but the biosorption process and mechanism of different components of microbial cells have not been elucidated. In present study, Pichia pastoris X33 and Cu2+ was used as a biosorption model to reveal the biosorption process and mechanism of different components of microbial cells. For the biosorption of whole cells, the maximum removal efficiency was 41.1%, and the adsorption capacity was 6.2 mg g-1. TEM-EDX analysis proved the existence of Cu2+ on the cell surface and cytoplasm. The maximum Cu2+ removal efficiency of the cell wall, cell membrane and cytoplasm were 21.2%, 20.7% and 18.5%, respectively. The optimum pH of Cu2+ biosorption of the P. pastoris cell, cell wall, cell membrane and cytoplasm was 6. Moreover, the maximum adsorption capacity of the cell, cell wall, cell membrane and cytoplasm was 16.13, 11.53, 10.97 and 8.87 mg g-1, respectively. The maximum removal efficiencies of P. pastoris biomass treated with proteinase K and P. pastoris biomass treated with ß-mannanase were 18.1% and 28.2%, respectively. The maximum removal efficiencies of mannan and glucan were 34% and 12%, respectively. The FTIR spectra showed that the amino group (N-H), hydroxyl (O-H), carbon oxygen bond (C-O), -CH, C-N and carbonyl group (C[double bond, length as m-dash]O) of a ketone or aldehyde may interact with Cu2+. Thus, our work provides guidance for further understanding the effect of different cell components on biosorption.

A high-performance functional phthalonitrile resin with a low melting point and a low dielectric constant.

A monomer of fluorinated phthalonitrile, namely 4,4'-bis(p-perfluoro-phenol-(bis(p-phenol)propane-2,2-diyl)-p-oxy-diphthalonitrile) (PBDP), was synthesized by the nucleophilic substitution reaction of bisphenol A, decafluorobiphenyl and 4-nitrophthalonitrile. The structure of the monomer was characterized by nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the PBDP monomer was synthesized successfully. The monomer was cured in the presence of 4-(aminophenoxy)phthalonitrile (APPH) and the curing behaviour was investigated by differential scanning calorimetry (DSC), suggesting a low melting point of 96 °C and an excellent processing window (96-262 °C). Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed that the fluorinated phthalonitrile resin possessed outstanding thermal and thermo-oxidative stabilities as well as good mechanical properties. The glass transition temperature was >400 °C and the 5% thermal degradation temperature was 501 °C. When the frequency was 50 MHz, the dielectric constant and dielectric loss of the polymer were 2.84 and 0.007, respectively. The PBDP resin has ultra-low water absorption of 0.77% and 1.4%, when exposed to an aqueous environment for 50 days at 24 °C and for 24 h at 100 °C, respectively. The prepared PBDP resin with outstanding thermal stability and low dielectric constant is an ideal candidate for aerospace industries, and microelectronic and other electronic packaging materials.

Anodic behaviour of Cu, Zr and Cu-Zr alloy in molten LiCl-KCl eutectic.

The anodic dissolution behaviours of Cu, Zr and Cu-Zr alloy were analysed in LiCl-KCl at 500°C by anode polarization curve and potentiostatic polarization curve. The results show that the initial and fast-dissolving potentials of Cu are -0.50 and -0.29 V, and Zr are -1.0 and -0.88 V, respectively. But, in the Cu-Zr alloy, the initial and fast-dissolving potentials of Cu are -0.52 and -0.41 V, and Zr are -0.96 and -0.92 V, respectively. The potentials satisfy the selection dissolution principle that Zr in the alloy dissolves first, while Cu is left in the anode and is not oxidized. The passivation phenomenon of Zr is observed in the quick dissolution of Zr, while it is not observed in the Cu-Zr alloy. Moreover, from the above anodic dissolution results, potentiostatic electrolysis of Cu-Zr alloy was carried out at -0.8 V for 40 min, and the anodic dissolution mechanism and kinetics of Zr in Cu-Zr alloy were also discussed. In the initial stage, Zr dissolves as Zr4+ ions from the alloy surface and enters into the molten salt, leaving a Cu layer called 'dissolving layer' on the surface of the alloy. After that, another layer between the matrix and 'dissolving layer' called 'diffusion-dissolution layer' appears. Zr diffuses in the alloy matrix and dissolves as Zr4+ ions on the surface of the 'diffusion-dissolution layer' continuously, and Zr4+ ions diffuse through the 'dissolving layer' and enter into the molten salt finally. In addition, the factors affecting the dissolution of Cu-Zr alloy, such as time and potential, were also investigated. The dissolution loss increases with the increasing dissolution potential and time, while the dissolution rate increases with the increasing dissolution potential and declines with the prolonging dissolution time.