Graphene Oxide-Based Composite Organohydrogels with High Strength and Low Temperature Resistance for Strain Sensors

In the recent years, a rapid development of the polymeric hydrogel-based sensors has been witnessed. However, conventional hydrogels often exhibit poor mechanical properties. Additionally, the use of these sensors at...

Photosynthesis and antioxidant metabolism modulate the low-temperature resistance of seed germination in maize

Spring maize is usually subjected to low-temperature stress during seed germination, which retards seedling growth even if under a suitable temperature. However, the mechanism underlying maize seed germination under low-temperature stress modulating seedling growth after being transferred to normal temperature is still ambiguous. In this study, we used two maize inbred lines with different low-temperature resistance (SM and RM) to investigate the mechanism. The results showed that the SM line had higher lipid peroxidation and lower total antioxidant capacity and germination percentage than the RM line under low-temperature stress, which indicated that the SM line was more vulnerable to low-temperature stress. Further transcriptome analysis revealed that seed germination under low-temperature stress caused down-regulation of photosynthesis related gene ontology (GO) terms in two lines. Moreover, the SM line displayed down-regulation of ribosome and superoxide dismutase (SOD) related genes, whereas genes involved in SOD and vitamin B6 were up-regulated in the RM line. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that photosynthesis and antioxidant metabolism related pathways played important roles in seed germination in response to low-temperature stress, and the photosynthetic system displayed a higher damage degree in the SM line. Both qRT-PCR and physiological characteristics experiments showed similar results with transcriptome data. Taken together, we propose a model for maize seed germination in response to low-temperature stress.

Synthesis of Low Temperature Resistant Hydrogenated Nitrile Rubber Based on Esterification Reaction

Hydrogenated Nitrile Rubber (HNBR) is widely used in aerospace, petroleum exploration and other fields because of its excellent performances. However, there remains a challenge of balancing the oil resistance and the low temperature resistance for HNBR. In this work, a series of grafted carboxyl nitrile rubber (XNBR) was prepared by the esterification reaction between active functional groups (–COOH) of XNBR and alkanols of different molecular chain lengths (C8H17OH, C12H25OH, C16H33OH, C18H37OH) or Methoxypolyethylene glycols (MPEG) of different molecular weights (Mn = 350, 750, 1000). The structure and low temperature resistance of as-obtained grafted polymers were characterized by Fourier Transform Infrared (FTIR), 1H-NMR and Differential scanning calorimetry (DSC). It was found that the glass transition temperatures (Tg) of grafted XNBR were significantly decreased. MPEG grafted polymers with better low temperature resistance were then selected for hydrogenation. As-prepared hydrogenated XNBR grafted with MPEG-1000 (HXNBR-g-1000) showed the lowest Tg of −29.8 °C and the best low temperature resistance. This work provides a novel and simple preparation method for low temperature resistant HNBR, which might be used potentially in extremely cold environments.

Assessment of the Possibility of Using Fly Ash from Biomass Combustion for Concrete

This article analyses the possibility of using fly ash from the combustion of wood–sunflower biomass in a fluidized bed boiler as an additive to concrete. The research shows that fly ash applied in an amount of 10–30% can be added as a sand substitute for the production of concrete, without reducing quality (compression strength and low-temperature resistance) compared to control concrete. The 28-day compressive strength of concrete with fly ash increases with the amount of ash added (up to 30%), giving a strength 28% higher than the control concrete sample. The addition of fly ash reduces the extent to which the compression strength of concrete is lowered after low-temperature resistance tests by 22–82%. The addition of fly ash in the range of 10–30% causes a slight increase in the water absorption of concrete. Concretes containing the addition of fly ash from biomass combustion do not have a negative environmental impact with respect to the leaching of heavy metal ions into the environment.

Low Temperature Resistance Increase for Bitumen by Compounding with Tar

In this paper, a conventional road bitumen with penetration grade 100–130 is compounded with tar in order to obtain bitumen with improved low temperature resistance. The low temperature (at −24 °C, −30 °C and −36 °C) resistance of the virgin bitumen and the compounded one is evaluated by testing on a bending beam rheometer. It was found that the optimum compounding (20% of tar by weight) decreases the stiffness essentially (from 18% to 34%), i.e., it increases the low temperature resistance of the bitumen. The stiffness decreases in the compounded bitumen can be explained by quantitative variations in its group chemical composition and molecular fragments. Group chemical composition has been determined by the method of absorption chromatography, and the fragments of molecules are identified by NMR-spectroscopy.

Validation of Adhesive and Temperature Property Characteristics of Microsurfacing by Performance-Based Mixture Design Approach

Performance-based mixture design of microsurfacing offers a promising solution to the best application of asphalt emulsions. The presented study investigated a novel approach to evaluate the spalling resistance and high and low-temperature resistance of microsurfacing. The laboratory tests, including mixture bond strength (MBS), driving wheel pavement analyzer (DWPA), multi-stress creep recovery (MSCR), load wheel rutting (LWR), and single edge notch beam (SENB) were conducted to characterize the performance-related properties; the response surface method (RSM) was used to obtain the optimal proportions of the mixture. According to the experimental results, the performance-based mixture design method improves the comprehensive performance of microsurfacing, such as adhesion at high and low temperatures. The results of RSM show that temperature is the most important factor that affects the adhesion of mixture. There is a strong correlation between adhesive and temperature performance detected by different test methods. Due to different chemical mechanisms caused by cement and emulsified asphalt, the high-temperature performance index of the microsurfacing mixture is lower than that of HMA. Furthermore, the low-temperature resistance is analyzed and suggested indicator is proposed.

Nitrogen Attenuated Zinc-Mediated Promotion of Rice Tillering Under Low Temperature via Regulating Auxin and Cytokinin Balance

Background and aims Zinc (Zn) can improve rice resistance to abiotic stress and participate in IAA synthesis. The absorption of Zn is closely related to nitrogen (N) nutrition. However, little is known about the mechanisms by which Zn regulates rice low-temperature resistance and tillering recovery after low-temperature under different N levels. Methods Water culture experiment was conducted with two temperatures (22°C and 12°C), two N levels (1.43 mM and 2.86 mM NH4NO3), and three Zn levels (0.08 µM, 0.15 µM and 0.30 µM ZnSO4·7H2O). Results Low-temperature decreased rice tillering, which was further exacerbated at high N levels. Increasing Zn application could improve rice low-temperature resistance under normal N levels, enhance nutrient absorption, improve tiller bud cytokinin (CTK) concentration and CTK/IAA ratio, finally accelerate tillering recovery one week before normal Zn treatment. High N attenuated the contribution of Zn under low temperature, but moderate Zn was beneficial to tillering recovery by regulating the balance of tiller bud IAA and CTK concentration, and IAA transport. Conclusions Increasing Zn application improved rice tolerance to low-temperature stress and promoted tillering recovery, which was aggravated under high N levels. However, appropriate Zn application under high N level was conducive to breaking tiller dormancy and promoting tillering growth spurts when recovering to a normal temperature, which was related to the hormone balance and nutrient absorption synergistic regulation by N and Zn.

Robust anomalous metallic states and vestiges of self-duality in two-dimensional granular In-InOx composites

Many experiments investigating magnetic-field tuned superconductor-insulator transition (H-SIT) often exhibit low-temperature resistance saturation, which is interpreted as an anomalous metallic phase emerging from a ‘failed superconductor’, thus challenging conventional theory. Here we study a random granular array of indium islands grown on a gateable layer of indium-oxide. By tuning the intergrain couplings, we reveal a wide range of magnetic fields where resistance saturation is observed, under conditions of careful electromagnetic filtering and within a wide range of linear response. Exposure to external broadband noise or microwave radiation is shown to strengthen the tendency of superconductivity, where at low field a global superconducting phase is restored. Increasing magnetic field unveils an ‘avoided H-SIT’ that exhibits granularity-induced logarithmic divergence of the resistance/conductance above/below that transition, pointing to possible vestiges of the original emergent duality observed in a true H-SIT. We conclude that anomalous metallic phase is intimately associated with inherent inhomogeneities, exhibiting robust behavior at attainable temperatures for strongly granular two-dimensional systems.

Expression and Characterization of a Thermostable Carrageenase From an Antarctic Polaribacter sp. NJDZ03 Strain

The complete genome of Polaribacter sp. NJDZ03, which was isolated from the surface of Antarctic macroalgae, was analyzed by next-generation sequencing, and a putative carrageenase gene Car3206 was obtained. Car3206 was cloned and expressed in Escherichia coli BL21(DE3). After purification by Ni-NTA chromatography, the recombinant Car3206 protein was characterized and the antioxidant activity of the degraded product was investigated. The results showed that the recombinant plasmid pet-30a-car3206 was highly efficiently expressed in E. coli BL21(DE3). The purified recombinant Car3206 showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight of 45 kDa. The optimum temperature of the recombinant Car3206 was 55°C, and it maintain 60–94% of its initial activity for 4–12 h at 55°C. It also kept almost 70% of the initial activity at 30°C, and more than 40% of the initial activity at 10°C. These results show that recombinant Car3206 had good low temperature resistance and thermal stability properties. The optimum pH of recombinant Car3206 was 7.0. Car3206 was activated by Na+, K+, and Ca2+, but was significantly inhibited by Cu2+ and Cr2+. Thin-layer chromatographic analysis indicated that Car3206 degraded carrageenan generating disaccharides as the only products. The antioxidant capacity of the degraded disaccharides in vitro was investigated and the results showed that different concentrations of the disaccharides had similar scavenging effects as vitamin C on O2•-, •OH, and DPPH•. To our knowledge, this is the first report about details of the biochemical characteristics of a carrageenase isolated from an Antarctic Polaribacter strain. The unique characteristics of Car3206, including its low temperature resistance, thermal stability, and product unity, suggest that this enzyme may be an interesting candidate for industrial processes.