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To make the colorless polyimides (CPIs) suitable for the application of flexible display technology, the polyimide (PI) films need to have both good optical properties and thermal properties. To get the wanted properties, 2‐(2‐methyl‐4‐(2‐methyl‐4‐aminobenzamido)phenyl)‐5‐(2‐methyl‐4‐aminobenzamido)‐N‐phenylbenzimidazol (5a) and 2‐(2‐methyl‐4‐(2‐trifluoromethyl‐4‐aminobenzamido)phenyl)‐5‐(2‐trifluoromethyl‐4‐aminobenzamido)‐N‐phenylbenzimidazol (5b) were synthesized, which both contained benzimidazole and bis‐amide structures. Two kinds of PI films were polymerized with cyclobutane‐1,2,3,4‐tetracarboxylic dianhydride (CBDA). With the contribution of side groups (CH3 or CF3), the resulting PI films presented relatively superior optical properties (transmittance at 400 nm was 59% and 68% respectively) and low coefficient of thermal expansion (CTE = 22 and 25 ppm K−1). These good properties suggest that these PI films have the potential for flexible display usage. [ABSTRACT FROM AUTHOR]

To provide polyimide (PI) with high heat resistance and ultra-low coefficient of thermal expansion (CTE) for use in flexible display substrates, a novel diamine with bisbenzimidazole and bisamide groups, namely N,N'-(1H,1'H-[5,5'-bibenzo[d]imidazole]-2,2'-diyl)bis(4-aminobenzamide) (BZBA), was designed and successfully synthesized. Several poly(benzimidazole-amide-imide) (PBIAI) films were prepared by thermal imidization with 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), and 4,4'-(hexafluoroisopropylindene)-diphthalic anhydride (6FDA), respectively. Among them, BZBA-BPDA has a high glass transition temperatures (T g = 345 °C) while achieving an extremely low coefficients of thermal expansion (CTE = 1.9 ppm K−1), meeting the processing requirements of polymer flexible substrates in OLED devices. The effects of different dianhydrides on the performance of PBIAIs were compared, providing a meaningful reference for further adjusting the PI molecular structure to meet specific requirements for industrial polymer films. [ABSTRACT FROM AUTHOR]

Saline and alkaline stresses limit plant growth and reduce crop yield. Soil salinization and alkalization seriously threaten the sustainable development of agriculture and the virtuous cycle of ecology. Biofertilizers made from plant growth−promoting rhizobacteria (PGPR) not only enhance plant growth and stress tolerance, but also are environmentally friendly and cost-effective. There have been many studies on the mechanisms underlying PGPRs enhancing plant salt resistance. However, there is limited knowledge about the interaction between PGPR and plants under alkaline–sodic stress. To clarify the mechanisms underlying PGPR's improvement of plants' tolerance to alkaline–sodic stress, we screened PGPR from the rhizosphere microorganisms of local plants growing in alkaline–sodic land and selected an efficient strain, Bacillus altitudinis AD13−4, as the research object. Our results indicate that the strain AD13−4 can produce various growth-promoting substances to regulate plant endogenous hormone levels, cell division and differentiation, photosynthesis, antioxidant capacity, etc. Transcriptome analysis revealed that the strain AD13−4 significantly affected metabolism and secondary metabolism, signal transduction, photosynthesis, redox processes, and plant–pathogen interactions. Under alkaline–sodic conditions, inoculation of the strain AD13−4 significantly improved plant biomass and the contents of metabolites (e.g., soluble proteins and sugars) as well as secondary metabolites (e.g., phenols, flavonoids, and terpenoids). The 16S rRNA gene sequencing results indicated that the strain AD13−4 significantly affected the abundance and composition of the rhizospheric microbiota and improved soil activities and physiochemical properties. Our study provides theoretical support for the optimization of saline–alkali-tolerant PGPR and valuable information for elucidating the mechanism of plant alkaline–sodic tolerance. [ABSTRACT FROM AUTHOR]

To improve the thermodynamic and mechanical properties of asymmetric polyimide (PI), a method to enhance the linearity of PI by using a structural reorganization approach was designed. First, two novel diamines containing benzimidazole and benzoxazole groups, namely PADBZ and PDBOA, were constructed and synthesized. Thereafter, two new kinds of PI films (PADBZ‐PMDA and PDBOA‐PMDA) were prepared and polymerized with 1,2,4,5‐benzenetetracarboxylic anhydride (PMDA). Based on structural reorganization, PADBZ‐PMDA and PDBOA‐PMDA had repeating units of the same chemical composition and different linearity with PABZ‐BPDA and BOA‐BPDA, respectively. Comparing PADBZ‐PMDA and PABZ‐BPDA, due to the transfer in the position of benzene, PADBZ‐PMDA with high linearity showed the improved heat resistance (Tg up to 448°C), dimensional stability (CTE down to 2.3 ppm/K) and mechanical properties. PDBOA‐PMDA and BOA‐BPDA had the same situation. This study provided a unique solution to enhance the performances of PI by increasing the linearity using a structural reorganization approach. [ABSTRACT FROM AUTHOR]

To synthesize colorless superheat‐resistant polyimide films, one of the valid approaches is the incorporation of the asymmetric and warped structures in the main chain. Applying this approach on 5(6)‐amino‐2‐(4‐aminobenzene)benzimidazole (PABZ) and changing its linearity, 6, 5′‐diamine‐2′‐methyl‐1‐methyl‐2‐phenylbenzimidazole (5a) and 6, 3′‐diamine‐2′‐methyl‐1‐methyl‐2‐phenylbenzimidazole (5b) were devised and synthesized successfully, then polymerized with 1,2,4,5‐cyclohexanetetracarboxylic dianhydride (HPMDA). The prepared poly(benzimidazole imide)s (PBIIs) with the rigid main chain and loose packing had the excellent heat‐resistant level (Tg > 400°C) and optical properties (T400 > 80%). Besides, the alterations resulting from various linearities were discussed comprehensively. This research is beneficial to the application of optical field, providing a promising candidate of heat‐resistant colorless materials. [ABSTRACT FROM AUTHOR]

Composite films of polytetrafluoroethylene (PTFE) and polyimide (PI) combine the advantages of both materials like excellent inertness to chemicals and thermal stability, which provide great potential in applications under harsh environments. However, strong adhesion between PTFE and PI layers still remains a big challenge. In this study, fluorinated ethylene propylene (FEP) as an intermediate layer was found to significantly enhance the adhesion of PTFE films to PI film, with peel strength up to 350 N/m in the manufactured direction comparing to the value of 0 for PTFE/PI composite film without FEP. It's superior to that of commercially available products (25 N/m) under the same test conditions. The improved performance is attributed to the formation of interlocks of molecules at the interfaces between the PTFE and FEP layers, and FEP and PI layers as observed in the images obtained by atomic force microscope (AFM) and scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

Soil saline–alkalization inhibits plant growth and development and seriously affects crop yields. Over their long-term evolution, plants have formed complex stress response systems to maintain species continuity. R2R3-MYB transcription factors are one of the largest transcription factor families in plants, widely involved in plant growth and development, metabolism, and stress response. Quinoa (Chenopodium quinoa Willd.), as a crop with high nutritional value, is tolerant to various biotic and abiotic stress. In this study, we identified 65 R2R3-MYB genes in quinoa, which are divided into 26 subfamilies. In addition, we analyzed the evolutionary relationships, protein physicochemical properties, conserved domains and motifs, gene structure, and cis-regulatory elements of CqR2R3-MYB family members. To investigate the roles of CqR2R3-MYB transcription factors in abiotic stress response, we performed transcriptome analysis to figure out the expression file of CqR2R3-MYB genes under saline–alkali stress. The results indicate that the expression of the six CqMYB2R genes was altered significantly in quinoa leaves that had undergone saline–alkali stress. Subcellular localization and transcriptional activation activity analysis revealed that CqMYB2R09, CqMYB2R16, CqMYB2R25, and CqMYB2R62, whose Arabidopsis homologues are involved in salt stress response, are localized in the nucleus and exhibit transcriptional activation activity. Our study provides basic information and effective clues for further functional investigation of CqR2R3-MYB transcription factors in quinoa. [ABSTRACT FROM AUTHOR]

Colorless polyimides (CPIs) with superheat resistance and low coefficient of thermal expansion (CTE) are required urgently to employ as plastic substrates in flexible‐display devices. To attain the target properties, 2‐(2‐methyl‐4‐(4‐aminobenzamido)phenyl)‐5‐(4‐aminobenzamido)‐N‐phenylbenzimidazol (AB‐MPBZ) that contains biamide was synthesized, and its homo‐ and co‐polyimides were prepared with 1,2,4,5‐cyclohexanetetracarboxylic dianhydride (HPMDA) and cyclobutane‐1,2,3,4‐tetracarboxylic dianhydride (CBDA). The crank‐shaft‐like amide groups effectively increases the linearity and stiffness of polymer segments, providing CPI films with low CTE. On the basis, the CBDA based poly(benzimidazole imide) (PBII) series with dense interchain packing exhibits further reduced CTE down to 22 ppm K−1 and increased glass‐transition temperature (Tg) up to 404 °C. Such good thermal properties indicate that the resultant copolyimides have potential applications as colorless flexible substrates. These provide a feasible approach to balance thermal and optical performance of polyimides. [ABSTRACT FROM AUTHOR]

Saline-alkali stress seriously affects the yield and quality of crops, threatening food security and ecological security. Improving saline-alkali land and increasing effective cultivated land are conducive to sustainable agricultural development. Trehalose, a nonreducing disaccharide, is closely related to plant growth and development and stress response. Trehalose 6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP) are key enzymes catalyzing trehalose biosynthesis. To elucidate the effects of long-term saline-alkali stress on trehalose synthesis and metabolism, we conducted an integrated transcriptome and metabolome analysis. As a result, 13 TPS and 11 TPP genes were identified in quinoa (Chenopodium quinoa Willd.) and were named CqTPS1-13 and CqTPP1-11 according to the order of their Gene IDs. Through phylogenetic analysis, the CqTPS family is divided into two classes, and the CqTPP family is divided into three classes. Analyses of physicochemical properties, gene structures, conservative domains and motifs in the proteins, and cis-regulatory elements, as well as evolutionary relationships, indicate that the TPS and TPP family characteristics are highly conserved in quinoa. Transcriptome and metabolome analyses of the sucrose and starch metabolism pathway in leaves undergoing saline-alkali stress indicate that CqTPP and Class II CqTPS genes are involved in the stress response. Moreover, the accumulation of some metabolites and the expression of many regulatory genes in the trehalose biosynthesis pathway changed significantly, suggesting the metabolic process is important for the saline-alkali stress response in quinoa. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa) is one of the most important crops grown worldwide, and saline–alkali stress seriously affects the yield and quality of rice. It is imperative to elucidate the molecular mechanisms underlying rice response to saline–alkali stress. In this study, we conducted an integrated analysis of the transcriptome and metabolome to elucidate the effects of long-term saline–alkali stress on rice. High saline–alkali stress (pH > 9.5) induced significant changes in gene expression and metabolites, including 9347 differentially expressed genes (DEGs) and 693 differentially accumulated metabolites (DAMs). Among the DAMs, lipids and amino acids accumulation were greatly enhanced. The pathways of the ABC transporter, amino acid biosynthesis and metabolism, glyoxylate and dicarboxylate metabolism, glutathione metabolism, TCA cycle, and linoleic acid metabolism, etc., were significantly enriched with DEGs and DAMs. These results suggest that the metabolites and pathways play important roles in rice's response to high saline–alkali stress. Our study deepens the understanding of mechanisms response to saline–alkali stress and provides references for molecular design breeding of saline–alkali resistant rice. [ABSTRACT FROM AUTHOR]

Polyimides (PIs) with super heat‐resistance and ultralow coefficient of thermal expansion (CTE) are required urgently to employ as plastic substrates in flexible‐display devices. To attain the target properties, we designed and synthesized a novel bibenzimidazole diamine characterized in having a N‐phenyl group, namely 1‐phenyl‐2,2′‐bibenzoimidazole‐5,5′‐diamine (PhDABZ), and focused on an aromatic poly(benzimidazole imide) series derived from 1,2,4,5‐benzenetetracarboxylic (PMDA). Incorporating bibenzimidazole and N‐substituent effectively increase the interchain interaction and chance for flexible film formation, which provides the PIs with high glass‐transition temperature (Tg > 480 °C) and dimensional stability (CTE < 10 ppm K−1). These data provide a feasible method to achieve higher thermal properties of PIs. [ABSTRACT FROM AUTHOR]

Herein, novel isomeric diamines containing semi-N-methyl substituted bisbenzimidazole and derived polyimides (PIs) were successfully synthesized. Experimental data showed that the obtained PIs exhibited outstanding heat resistance and dimensional stability, including 5 % thermal weight loss temperature (Td5 %) of 547 ~ 557 °C, high glass transition temperature (Tg) of 407 ~ 423 °C, and low coefficient of thermal expansion (CTE) of 2.2 ~ 17.6 ppm/°C. The influence of molecular structure of isomeric diamines, including para and ortho substituted N-methyl, on the molecular packing and properties of polymer was discussed. As a result, the novel PIs showed lower CTE than traditional PABZ (5-amino-2-(4-aminobenzene)-benzimidazole) based PIs without bringing high water absorption. These high-performance PI films with matching CTE of copper have potential applications in flexible display substrates and printed circuit boards. [ABSTRACT FROM AUTHOR]

Histone deacetylases (HDACs) play crucial roles nearly in all aspects of plant biology, including stress responses, development and growth, and regulation of secondary metabolite biosynthesis. The molecular functions of HDACs have been explored in depth in Arabidopsis thaliana , while little research has been reported in the medicinal plant Cannabis sativa L. Here, we excavated 14 CsHDAC genes of C. sativa L that were divided into three relatively conserved subfamilies, including RPD3/HDA1 (10 genes), SIR2 (2 genes), and HD2 (2 genes). Genes associated with the biosynthesis of bioactive constituents were identified by combining the distribution of cannabinoids with the expression pattern of HDAC genes in various organs. Using qRT-PCR and transcription group analysis, we verified the expression of candidate genes in different tissues. We found that the histone inhibitor Trichostatin A (TSA) affected the expression of key genes in the cannabinoid metabolism pathway and the accumulation of synthetic precursors, which indirectly indicates that histone inhibitor may regulate the synthesis of active substances in C. sativa L. [ABSTRACT FROM AUTHOR]

Conductive polyimide (PI) film electrodes, which combine the electrical conductivity of silver nanowires (AgNWs) with multi-stimulus response properties, are promising for smart devices, such as actuators, remote sensing circuits, intelligent garments, and smart flexible robots. The flexible electrodes are fabricated using shape memory polyimide as the substrate. In addition, a thermally cured liquid photopolymer, SR 368D, was used as a transition layer and AgNWs served as the conductive layer (denoted as AgNW/SR/PI electrode). The AgNW/SR/PI electrodes exhibited a low resistivity of ∼1.3 Ω sq−1 because of the high conductivity of the AgNWs. Integrating the high strength of PI films with AgNWs gave the electrodes highly conductive and stable properties. The electrodes were able to maintain a low resistivity of ∼1.5 Ω sq−1 even after 2000 bending/unbending cycles and retained ∼1.8 Ω sq−1 after 2000 adhesion/peeling cycles. Moreover, the AgNW possessed conductivity and infrared absorption, and the flexible electrodes recovered the initial shape under the effects of Joule heating and photo-thermal trigger by an electric stimulus and photo stimulus. [ABSTRACT FROM AUTHOR]

ABSTRACT Blends of polyether sulfone (PES) and polyphenylene sulfide (PPS) with different weight ratios (10/0, 8/2, 6/4, 4/6, 2/8, 0/10) were prepared by melt extrusion using a twin-screw extruder. In this work, the thermal stabilities of blends were evaluated by thermogravimetric analysis and the dynamic mechanical properties were investigated by means of dynamic mechanical analysis. The fracture surfaces were observed with a scanning electron microscopy. In addition, the mechanical property tests were also carried out and the impact strength of blends was improved by 110% compared to that of pure PPS. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41703. [ABSTRACT FROM AUTHOR]

Tartary buckwheat is rich in flavonoids, which not only play an important role in the plant-environment interaction, but are also beneficial to human health. Rutin is a therapeutic flavonol which is massively accumulated in Tartary buckwheat. It has been demonstrated that transcription factors control rutin biosynthesis. However, the transcriptional regulatory network of rutin is not fully clear. In this study, through transcriptome and target metabolomics, we validated the role of FtMYB102 and FtbHLH4 TFs at the different developmental stages of Tartary buckwheat. The elevated accumulation of rutin in the sprout appears to be closely associated with the expression of FtMYB102 and FtbHLH4. Yeast two-hybrid, transient luciferase activity and co-immunoprecipitation demonstrated that FtMYB102 and FtbHLH4 can interact and form a transcriptional complex. Moreover, yeast one-hybrid showed that both FtMYB102 and FtbHLH4 directly bind to the promoter of chalcone isomerase (CHI), and they can coordinately induce CHI expression as shown by transient luciferase activity assay. Finally, we transferred FtMYB102 and FtbHLH4 into the hairy roots of Tartary buckwheat and found that they both can promote the accumulation of rutin. Our results indicate that FtMYB102 and FtbHLH4 can form a transcriptional complex by inducing CHI expression to coordinately promote the accumulation of rutin. Tartary buckwheat is renowned for its high flavonoid content, particularly rutin. There are several new findings in this study: • We found that flavonoids, specifically rutin, were also abundant in sprout and seedling, and that the content decreased as the plant matured from sprout to seedling. • We discovered that two new transcription factors, FtMYB102 and FtbHLH4, can regulate rutin biosynthesis. • FtMYB102 and FtbHLH4 can interact with each other to form a transcriptional complex that regulates target genes expression. [ABSTRACT FROM AUTHOR]

Nanosized titanium oxide (TiO2) material is a promising photocatalyst for the degradation of organic pollutants, whereas the difficulty of its recycling hinders its practical application. Herein, we reported the preparation of a novel titanium oxide/polysulfone (TiNPs/PSF) composite hollow microspheres by the combination of Pickering emulsification and the solvent evaporation technique and their application for the photodegradation of methyl blue (MB). P25 TiO2 nanoparticles dispersed on the surface of PSF microspheres. The porosity, density and photoactivity of the TiNPs/PSF composite microsphere are influenced by the TiO2 loading amount. The composite microsphere showed good methyl blue (MB) removal ability. Compared with TiO2 P25, and PSF, a much higher MB adsorption speed was observed for TiNPs/PSF microspheres benefited from their porous structure and the electrostatic attractions between the MB+ and the negatively charged PSF materials, and showed good degradation efficiency. For TiNPs/PSF composite microsphere with density close to 1, a 100% MB removal (10 mg L−1) within 120 min at a catalyst loading of 2.5 g L−1 can be obtained under both stirring and static condition, due to well dispersing of TiO2 particles on the microsphere surface and its stable suspending in water. For the non-suspended TiNPs/PSF composite microsphere with density bigger than 1, the 100% MB removal can be only obtained under stirring condition. The removal efficiency of MB for the composite microspheres retained 96.5%, even after 20 cycles. Moreover, this composite microsphere also showed high MB removal ability at acidic condition. The high catalysis efficiency, excellent reusability and good stability make this kind of TiNPs/PSF composite microsphere a promising photocatalyst for the water organic pollution treatment. [ABSTRACT FROM AUTHOR]

To achieve polyimide-metal complexes with enhanced properties, 5-amine-2-(5-aminopyridin-2-yl)-1-methyl-benzimidazole (PyMePABZ) that contains stiff 2-(2′-pyridyl)benzimidazole (PyBI) was synthesized and exploited to construct the Cu(ΙΙ)-crosslinked polyimides (Cu-PIs). These Cu-PIs exhibited higher dielectric, thermal, and mechanical properties with an increase in Cu2+ content. Among them, their dielectric constants (εrS) were up to 43% superior to that of the neat PI, glass transition temperatures (Tgs) were all over 400 °C, and 5% weight loss temperature (T5%) maintained beyond 500 °C. These data indicate that the metal coordination crosslinking provided a useful guide to develop high performance PIs which possess potential application as useful high temperature capacitors. [ABSTRACT FROM AUTHOR]

As the continuous development of aerospace and outer space exploration, high-performance thermal insulation materials with high-temperature resistance and attractive mechanical properties have always been a fascinating topic of research to protect human body or components from extreme environments. In this research, hydrophobic silicon dioxide (SiO2) nanoparticles as molecular skeleton enhancers and heat transfer inhibitors are introduced in crosslinked polyimide (PI) aerogels with rigid molecular structure to maintain the stable nanoporous network structure. The density, shrinkage, porosity, specific surface area and pore size distribution of PI/SiO2 composite aerogels can be adjusted by the addition of SiO2 nanoparticles, so as to improve the comprehensive performances. The excellent thermal stability and mechanical properties of PI/SiO2 composite aerogels with super-high working temperature of over 550 °C and high modulus of compression and tension (compression Young’s modulus of 37.75 MPa and tensile modulus of 237.1 MPa) ensure their use as a structural component. The charming thermal conductivity (29.7 mWm−1 K−1) and excellent flame resistance make them a candidate for high-performance thermal insulation materials.Graphical abstract: As the continuous development of aerospace and outer space exploration, high-performance thermal insulation materials with high-temperature resistance and attractive mechanical properties have always been a fascinating topic of research to protect human body or components from extreme environments. In this research, hydrophobic silicon dioxide (SiO2) nanoparticles as molecular skeleton enhancers and heat transfer inhibitors are introduced in crosslinked polyimide (PI) aerogels with rigid molecular structure to maintain the stable nanoporous network structure. The density, shrinkage, porosity, specific surface area and pore size distribution of PI/SiO2 composite aerogels can be adjusted by the addition of SiO2 nanoparticles, so as to improve the comprehensive performances. The excellent thermal stability and mechanical properties of PI/SiO2 composite aerogels with super-high working temperature of over 550 °C and high modulus of compression and tension (compression Young’s modulus of 37.75 MPa and tensile modulus of 237.1 MPa) ensure their use as a structural component. The charming thermal conductivity (29.7 mWm−1 K−1) and excellent flame resistance make them a candidate for high-performance thermal insulation materials. [ABSTRACT FROM AUTHOR]