No abstract

Polymer‐based materials with high electrical conductivity are of considerable interest because of their wide range of applications. The construction of a 3D, compactly interconnected graphene network can offer a huge increase in the electrical conductivity of polymer composites. However, it is still a great challenge to achieve desirable 3D architectures in the polymer matrix. Here, highly conductive polymer nanocomposites with 3D compactly interconnected graphene networks are obtained using a self‐assembly process. Polystyrene (PS) and ethylene vinyl acetate (EVA) are used as polymer matrixes. The obtained PS composite film with 4.8 vol% graphene shows a high electrical conductivity of 1083.3 S/m, which is superior to that of the graphene composite prepared by a solvent mixing method. The electrical conductivity of the composites is closely related to the compact contact between graphene sheets in the 3D structures and the high reduction level of graphene sheets. The obtained EVA composite films with the 3D graphene structure not only show high electrical conductivity but also exhibit high flexibility. Importantly, the method to fabricate 3D graphene structures in polymer matrix is facile, green, low‐cost, and scalable, providing a universal route for the rational design and engineering of highly conductive polymer composites.

The incorporation of graphene sheets (GSs) into polymer matrices affords engineers an opportunity to synthesize polymer composites with excellent physical performances. However, the development of high performance GS-based composites is difficult because of the easy aggregation of GSs in a polymer matrix as well as the weak interfacial adhesion between GSs and the host polymer. Herein, we present a simple and effective route to hyperbranched aromatic polyamide functionalized graphene sheets (GS-HBA). The resulting GS-HBA exhibits uniform dispersion in a thermoplastic polyurethane (TPU) matrix and strong adhesion with the matrix by hydrogen-bond coupling, which improve the load transfer efficiency from the matrix to the GSs. Thus, the GS-HBA-TPU composites possess excellent mechanical performance and high dielectric performance. It has been demonstrated that the GS-HBA composite has higher modulus, higher tensile strength and higher yield strength, and remains at nearly the same strain at break when compared with the composites with graphene oxide, ethylene diaminemodified graphene, and hydrazine reduced graphene. In addition, the hyperbranched polymer chains allow construction of a large number of microcapacitors and suppress the leakage current by isolating the GSs in a TPU matrix, resulting in a higher permittivity and lower loss tangent for the GS-HBA composite in comparison with ethylene diamine-modified graphene, or hydrazine reduced-graphene composites.

The primary clinical and radiographic efficacies of both ROI-C and cages with plates in ACDF for MCSM were satisfactory; both approaches could improve and maintain cervical lordosis and disk height. However, the ROI-C was associated with a simpler operation, a shorter operation time, less blood loss, and a lower risk of postoperative dysphagia compared to the PEEK cage with an anterior plate.

Heat stress negatively affects reproduction in cattle by disrupting the normal function of ovarian granulosa cells (GCs), ultimately leading to oxidative damage and cell death via apoptosis. Heme oxygenase-1(HO-1) is a member of the heat shock protein family, which are associated with cellular antioxidant defenses and anti-apoptotic functions. Recent studies demonstrated that HO-1 is upregulated in heat-stressed cells. In the present study, we investigated the expression of HO-1 in bovine GCs transiently exposed to heat stress and characterized the expression and activity of key oxidative stress enzymes and molecules. We show that heat stress induced oxidative stress and apoptosis, and enhanced Nrf2 and HO-1 expression in primary GC cultures. Knocking down HO-1 expression using siRNA exacerbated both oxidative stress and apoptosis, whereas pre-treating GCs with hemin, which induces HO-1 expression, partially prevented these effects. These findings demonstrate that HO-1 attenuates heat stress-induced apoptosis in bovine GCs by decreasing production of reactive oxygen species and activating the antioxidant response.

MicroRNAs (miRNAs) are small single-stranded non-coding RNAs that have an important regulatory function in animal growth and developmental processes. However, the differential expression of miRNA and the role of these miRNAs in heat-stressed Holstein cows are still unknown. In this study, the profile of differentially expressed miRNAs and the target genes analysis in the serum of heat-stressed and normal Holstein cows were investigated by a Solexa deepsequencing approach and bioinformatics. The data identified 52 differentially expressed miRNAs in 486 known miRNAs which were changed significantly between heat-stressed and normal Holstein cows (fold change >2, P<0.001). Target genes analysis showed that at least 7 miRNAs (miR-19a, miR-19b, miR-146a, miR-30a-5p, miR-345-3p, miR-199a-3p, and miR-1246) were involved in the response to stress, oxidative stress, development of the immune system, and immune response among the identified 52 differentially expressed miRNAs. Five miRNAs (miR-27b, miR-181a, miR-181b, miR-26a, and miR-146b) were involved in stress and immune responses and the expression of five miRNAs was striking (P<0.001). In addition, RT-qPCR and deepsequencing methods showed that 8 miRNAs among the 12 selected miRNAs (miR-19a, miR-19b, miR-27b, miR-30a-5p, miR-181a, miR-181b, miR-345-3p, and miR-1246) were highly expressed in the serum of heat-stressed Holstein cows. GO and KEGG pathway analysis showed that these differentially expressed miRNAs were involved in a pathway that may differentially regulate the expression of stress response and immune response genes. Our study provides an overview of miRNAs expression profile and the interaction between miRNAs and their target genes, which will lead to further understanding of the important roles of miRNAs in heat-stressed Holstein cows.

PCR low ionic strength single-strand conformation polymorphism (PCR-LIS-SSCP) and DNA sequencing methods were used to analyze the polymorphisms within the coding region of bovine ATP1A1 gene. A novel C/A mutation was identified at the nucleotide position 2789 of the ATP1A1 mRNA, but it was silent with respect to the amino acid sequence of the protein. The LIS-SSCP banding pattern could be divided into three kinds of genotypes, named CC, CA, and AA. Also, the association of the novel SNP of ATP1A1 gene with heat tolerance traits was studied, we found that the individuals with genotype CC showed significantly higher heat resistance than those of genotype CA (P<0.05). Further, the mRNA levels of ATP1A1 gene in lymphocytes of peripheral blood in dairy cows among various temperature groups and genotypes were analyzed by using real-time RT-PCR. Results showed that the expression of ATP1A1 mRNA was highest in heat-stressed cows with CC genotype among the three genotypes (P<0.01), and the ATP1A1 mRNA level at temperature 32.5°C was higher than that at optimal temperature 12.5°C in dairy cows (P<0.01). Simultaneity, the plasma potassium (K+, mmol/l) and sodium (Na+, mmol/l) declined when the temperature dropped (P<0.05). Our findings implied that the novel SNP here could be a potential genetic marker for anti-heat stress trait in dairy cow breeding.

Rising temperatures are severely affecting the mortality, laying performance, and meat quality of duck. Our aim was to investigate the effect of acute heat stress on the expression of heat shock proteins (HSPs: HSP90, 70, 60, 40, and 10) and inflammatory factors (nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2)) and antioxidant enzyme activity (superoxide dismutase (SOD), malondialdehybe (MDA), catalase (CAT), total antioxidant capacity (T-AOC)) in livers of ducks and to compare the thermal tolerance of Pekin and Muscovy ducks exposed to acute heat stress. Ducks were exposed to heat at 39 ± 0.5 °C for 1 h and then returned to 20 °C for 1 h followed by a 3-h recovery period. The liver and other tissues were collected from each individual for analysis. The mRNA levels of HSPs (70, 60, and 40) increased in both species, except for HSP10, which was upregulated in Muscovy ducks and had no difference in Pekin ducks after heat stress. Simultaneously, the mRNA level of HSP90 decreased in the stress group in both species. Morphological analysis indicated that heat stress induced tissue injury in both species, and the liver of Pekin ducks was severely damaged. The activities of several antioxidant enzymes increased in Muscovy duck liver, but decreased in Pekin duck. The mRNA levels of inflammatory factors were increased after heat stress in both duck species. These results suggested that heat stress could influence HSPs, inflammatory factors expression, and the activities of antioxidant enzymes. Moreover, the differential response to heat stress indicated that the Muscovy duck has a better thermal tolerance than does the Pekin duck.