Stress response membrane protein OsSMP2 negatively regulates rice tolerance to drought.

In a gene chip analysis, rice (Oryza sativa) OsSMP2 gene expression was induced under various abiotic stresses, prompting an investigation into its role in drought resistance and abscisic acid signaling. Subsequent experiments, including qRT-PCR and ß-glucuronidase activity detection, affirmed the OsSMP2 gene's predominant induction by drought stress. Subcellular localization experiments indicated the OsSMP2 protein primarily localizes to the cell membrane system. Overexpressing OsSMP2 increased sensitivity to exogenous abscisic acid, reducing drought resistance and leading to reactive oxygen species accumulation under drought stress. Conversely, in simulated drought experiments, OsSMP2-silenced transgenic plants showed significantly longer roots compared with the wild-type Nipponbare. These results suggest that OsSMP2 overexpression negatively affects rice drought resistance, offering valuable insights into molecular mechanisms, and highlight OsSMP2 as a potential target for enhancing crop resilience to drought stress.

Effects of Plant Regulators on the Seed Germination and Antioxidant Enzyme Activity of Cotton under Compound Salt Stress.

Salinity stress significantly hampers cotton seed germination and seedling growth. Employing plant growth regulators stands out as an effective strategy to mitigate salt stress. In this study, we assessed the impact of varying concentrations of natural composite salt conditions (0%, 0.6%, and 1.2%) on cotton seed germination, seedling growth, and physiology. Additionally, we explored the effects of compound sodium nitrophenolate (CSN: 2 mg·L-1 and 10 mg·L-1), 24-epibrassinolide (EBR: 0.02 mg·L-1 and 0.1 mg·L-1), and gibberellic acid (GA: 60 mg·L-1 and 300 mg·L-1), against a control (CK: distilled water) group. The results indicate that with an increase in the composite salt concentration, the germination potential (GP) and germination rate (GR) of cotton seeds gradually decrease. Simultaneously, the fresh weight and root vitality of seedlings also correspondingly decrease, while the degree of membrane lipid peroxidation increases. Under high-salt (1.2%) conditions, soaking treatments with CSN and EBR significantly enhance both GP (45-59% and 55-64%) and GR (30-33% and 39-36%) compared to the CK. However, the GA treatment does not increase the GP and GR of cotton. Moreover, under high-salt (1.2%) conditions, CSN and EBR treatments result in the increased activities of superoxide dismutase (56-66% and 71-80%), peroxidase (20-24% and 37-51%), and catalase (26-32% and 35-46%). Consequently, cotton exhibits a relatively good tolerance to natural composite salts. Soaking treatments with CSN and EBR effectively improve cotton germination by enhancing antioxidant enzyme activities, thereby strengthening cotton's tolerance to salt stress. These findings offer new insights for enhancing the salt tolerance of cotton.

AP2/EREBP Pathway Plays an Important Role in Chaling Wild Rice Tolerance to Cold Stress.

Cold stress is the main factor limiting rice production and distribution. Chaling wild rice can survive in cold winters. AP2/EREBP is a known transcription factor family associated with abiotic stress. We identified the members of the AP2/EREBP transcription factor family in rice, maize, and Arabidopsis, and conducted collinearity analysis and gene family analysis. We used Affymetrix array technology to analyze the expression of AP2/EREBP family genes in Chaling wild rice and cultivated rice cultivar Pei'ai64S, which is sensitive to cold. According to the GeneChip results, the expression levels of AP2/EREBP genes in Chaling wild rice were different from those in Pei'ai64S; and the increase rate of 36 AP2/EREBP genes in Chaling wild rice was higher than that in Pei'ai64S. Meanwhile, the MYC elements in cultivated rice and Chaling wild rice for the Os01g49830, Os03g08470, and Os03g64260 genes had different promoter sequences, resulting in the high expression of these genes in Chaling wild rice under low-temperature conditions. Furthermore, we analyzed the upstream and downstream genes of the AP2/EREBP transcription factor family and studied the conservation of these genes. We found that the upstream transcription factors were more conserved, indicating that these upstream transcription factors may be more important in regulating cold stress. Meanwhile, we found the expression of AP2/EREBP pathway genes was significantly increased in recombinant inbred lines from Nipponbare crossing with Chaling wild rice, These results suggest that the AP2/EREBP signaling pathway plays an important role in Chaling wild rice tolerance to cold stress.

Exogenous γ-Aminobutyric Acid Can Improve Seed Germination and Seedling Growth of Two Cotton Cultivars under Salt Stress.

Excessive salt content in soil has adverse effects on cotton production, especially during the germination and seedling stages. γ-aminobutyric acid (GABA) is an important active substance that is expected to improve the resistance of plants to abiotic stresses. This study focused on two cotton cultivars (Gossypium hirsutum L.: Tahe 2 and Xinluzhong 62) and investigated the impact of exogenous GABA (0, 1, 2, 3, and 4 mM) on seed germination, seedling growth, and related morphological, physiological, and biochemical indicators under salt stress (150 mM NaCl). The results showed that salt stress significantly reduced the germination rate and germination index of cotton seeds (decreased by 20.34% and 32.14% for Tahe 2 and Xinluzhong 62, respectively), leading to decreased seedling height and biomass and causing leaf yellowing. Salt stress induced osmotic stress in seedlings, resulting in ion imbalance (marked reduction in K+/Na+ ratio) and oxidative damage. Under salt stress conditions, exogenous GABA increased the germination rate (increased by 10.64~23.40% and 2.63~31.58% for Tahe 2 and Xinluzhong 62, respectively) and germination index of cotton seeds, as well as plant height and biomass. GABA treatment improved leaf yellowing. Exogenous GABA treatment increased the content of proline and soluble sugars, with varying effects on betaine. Exogenous GABA treatment reduced the Na+ content in seedlings, increased the K+ content, and increased the K+/Na+ ratio (increased by 20.44~28.08% and 29.54~76.33% for Tahe 2 and Xinluzhong 62, respectively). Exogenous GABA treatment enhanced the activities of superoxide dismutase and peroxidase, and reduced the accumulation of hydrogen peroxide and malondialdehyde, but had a negative impact on catalase activity. In conclusion, exogenous GABA effectively improved cotton seed germination. By regulating osmoprotectant levels, maintaining ion homeostasis, and alleviating oxidative stress, GABA mitigated the adverse effects of salt stress on cotton seedling growth.

Facile preparation of graphene@polyaniline nanofiber network/oxidized carbon cloth composites for high-performance flexible solid-state supercapacitors.

The complicated preparation process and low energy density of polyaniline (PANI)-based electrodes limit their wide applications in flexible energy storage devices. In this work, a reduced graphene (rGO)-wrapped polyaniline nanofiber network (PANI-NFN)/oxidized carbon cloth (OCC) (rGO@PANI-NFN/OCC) composite was prepared by a facile impregnation method using reactive templates of MnO2 on the surface of OCC. The as-prepared rGO@PANI-NFN/OCC composite exhibited a high area specific capacitance of 4438 mF cm-2 and maintained an initial capacitance of 88.2% after 3000 GCD cycles. It can be used as an independent electrode to construct flexible solid-state supercapacitors (FSSCs), and the FSSCs based on rGO@PANI-NFN/OCC also exhibit a high energy density of 117.9 µW h cm-2 and 88.39% retention after 500 bending cycles, which shows a great prospect for flexible energy storage device applications. The enhanced performance of rGO@PANI-NFN/OCC composites is mainly attributed to the synergistic effect of PANI-NFN structures with a large specific surface area and a rGO wrap layer to reduce the swelling and shrinking of PANI.

Synthesis of Aluminum Phosphate-Coated Halloysite Nanotubes: Effects on Morphological, Mechanical, and Rheological Properties of PEO/PBAT Blends.

Polymer blending has been widely used to fabricate polymeric films in the last decade due to its superior properties to a single component. In this study, an aluminum phosphate-coated halloysite nanotube (HNTs@AlPO4) was fabricated using a one-pot heterogeneous precipitation method, organically modified HNTs@AlPO4 (o-HNTs@AlPO4) was used to improve the performance of polyethylene oxide/poly(butylene adipate-co-terephthalate) (PEO/PBAT) blends, and the mechanical and rheological properties of the PEO/PBAT/o-HNTs@AlPO4 films were systematically discussed. According to our results, there is an optimal addition for adequate AlPO4 nanoparticle dispersion and coating on the surface of HNTs, and organic modification could improve the interfacial compatibility of HNTs@AlPO4 and the polymeric matrix. Moreover, o-HNTs@AlPO4 may serve as a compatibilizer between PEO and PBAT, and PEO/PBAT/o-HNTs@AlPO4 films have better mechanical and rheological properties than the PEO/PBAT blends without the o-HNTs@AlPO4 component.

Synergistic Effects of DOPO-Based Derivative and Organo-Montmorillonite on Flame Retardancy, Thermal Stability and Mechanical Properties of Polypropylene.

Polypropylene (PP), as a general thermoplastic polymer, is broadly used in different fields. However, the high flammability, melt dripping and poor mechanical properties of PP are a constraint to the expansion of its applications. In this paper, PP composites containing a combination of a phenethyl-bridged DOPO derivative (PN-DOPO) and organic montmorillonite (OMMT) were prepared via melt blending. The synergistic effects of PN-DOPO and OMMT on the flame retardancy, thermal stability and mechanical properties of PP composites were investigated systematically. The results showed that 20 wt% addition of PN-DOPO with OMMT improved the flame retardancy of PP composites. In particular, the introduction of 17 wt% PN-DOPO and 3 wt% OMMT increased the LOI values of the PP matrix from 17.2% to 23.6%, and the sample reached the V-0 level and reduced the heat release rate and total heat release. TGA indicated that OMMT could improve the thermal stability of the PP/PN-DOPO blends and promote the char residues of PP systems. Rheological behaviour showed a higher storage modulus, loss modulus and complex viscosity of PP/PN-DOPO/OMMT composites, suggesting a more effective network structure. In addition, the tensile strength, flexural properties and impact strength of the PP/PN-DOPO/OMMT composites actually increased for a good dispersion effect. Combined with the char layer analysis, the introduction of OMMT promoted more continuous and compact structural layers containing an aluminium-silicon barrier and phosphorus-containing carbonaceous char in the condensed phase. OMMT can improve the flame retardancy, thermal stability and mechanical properties of PP, and, thus, PN-DOPO/OMMT blends can serve as an efficient synergistic system for flame-retarded PP composites.

Signal-on photoelectrochemical immunoassay for salivary cortisol based on silver nanoclusters-triggered ion-exchange reaction with CdS quantum dots.

Nowadays, the epidemic, employment, and academic pressures are seriously affecting our physical and mental health. Herein, we designed a magneto-controlled photoelectrochemical immunosensor for noninvasive monitoring of salivary cortisol regarded as a pressure biomarker. A competitive immunoassay model was established by coupling bovine serum albumin-cortisol modified magnetic beads (MB-BSA-cortisol) with silver nanoclusters (Ag NCs)-labelled anti-cortisol antibody, and quantity analysis was operated by photoelectrochemical measurement of the CdS/Au electrode as an ion-exchange platform. Accompanying the formation of immune complexes, the carried Ag NCs were readily dissolved with nitric acid to produce abundant silver ions, which transferred to the electrode for ion-exchange reaction with CdS quantum dots to produce Ag2S, a new electron-hole capture site, leading to a decrease in the photocurrent intensity. The photocurrent signal gradually recovered with the increase of concentration of target cortisol, acquiring the signal-on mode competitive immunosensing system, which is propitious to the detection of small molecules. Within optimal conditions, this sensor had a satisfactory linear relationship in the range of 0.0001-100 ng mL-1 with favorable repeatability, specificity, and acceptable method accuracy. The detection limit was as low as 0.06 pg mL-1. In addition, this strategy provided new thought for the test of other small-molecule analytes and immunosensor applied in the complex biological system.

Flame-Retardant Performance of Epoxy Resin Composites with SiO2 Nanoparticles and Phenethyl-Bridged DOPO Derivative.

Flame retardancy of epoxy resin (EP) plays a vital role in its applications. When inorganic nanomaterials form inorganic/organic nanocomposites, they exhibit special flame-retardant effects. In this study, EP nanocomposites were prepared by the incorporation of SiO2 nanoparticles and phenethyl-bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative (DiDOPO), and the synergistic effects of SiO2 nanoparticles and DiDOPO on the flame-retardant performance of EP were discussed. Results indicated that the introduction of only 15 wt % SiO2 and 5 wt % DiDOPO in EP leads to the increase in the limiting oxygen index from 21.8 to 30.2%, and the nanocomposites achieve the UL-94 V-0 rating. Thermogravimetric analysis revealed that char yield increases with the increase in the SiO2 content of the nanocomposites and that an increased amount of thermally stable carbonaceous char is formed. SiO2 nanoparticles can improve the thermal stability and mechanical performance of EP; hence, the nanoparticles can serve as an efficient adjuvant for the DiDOPO/EP flame-retardant system.

Influence of choice of substrate and film thickness on magneto-optical properties of SmFeO3 thin films.

Herein, SmFeO3 thin films are prepared by using magnetron sputtering technology on quartz-glass and SrTiO3(STO)(1 0 0) substrates. The influence of film thickness and choice of substrate on film quality and growth orientation is studied in detail. Moreover, the impact of phase purity and growth orientation on optical, magnetic and magneto-optical properties is discussed. The results reveal that the film thickness and choice of substrate significantly influence the induced stresses at film/substrate interface and growth orientation of the annealed film. The as-fabricated SmFeO3 thin films have demonstrated highly crystalline structure, excellent transmittance and enhanced magneto-optical properties. Moreover, obvious anisotropy in magnetization and magneto-optical properties has been observed. The SmFeO3 films with excellent magneto-optical properties can be fabricated by selecting optimal film thickness and substrate. It is expected that SmFeO3 film is a promising material for integrated optical isolators and magneto-optical modulators.

Actuation Behavior of Multilayer Graphene Nanosheets/Polydimethylsiloxane Composite Films.

The graphene nanosheets (GNS)/polydimethylsiloxane (PDMS) composite films with out-of-plane dielectric actuation behavior were prepared through a layer-by-layer spin coating process. The GNS-PDMS/PDMS composite films with 1~3 layers of GNS-PDMS films were spin coated on top of the PDMS film. The dielectric, mechanical, and electromechanical actuation properties of the composite films were investigated. The dielectric constant of the GNS-PDMS³/PDMS composite film at 1 kHz is 5.52, which is 1.7 times that of the GNS-PDMS¹/PDMS composite film. The actuated displacement of the GNS-PDMS/PDMS composite films is greatly enhanced by increasing the number of GNS-PDMS layers. This study provides a novel alternative approach for fabricating high-performance actuators with out-of-plane actuation behavior.