可重复加工型生物基热固性自修复聚氨酯树脂的合成与性能

热固性聚氨酯树脂存在不可重复加工等问题,大大降低了材料的使用寿命,同时造成资源浪费。文中以水热法制备了以羟甲基化木质素(Lig-OH)为生物基软段、异佛尔酮二异氰酸酯(IPDI)为硬段、三羟甲基丙烷(TMP)为交联型扩链剂、4,4’-二氨基二苯二硫醚(4-SO)为二次扩链剂、4-甲基伞形酮(4-MU)为生物基封端剂的可重复加工型生物基热固性聚氨酯树脂(LPU)。通过傅里叶变换红外光谱表征其结构,通过光学显微镜、3D轮廓仪等研究其自修复性能,通过拉伸测试、重复加工测试对其力学性能和可重复性进行研究。结果表明,LPU-5(TMP用量为18 mmol)的力学性能最佳,拉伸强度可达18.92 MPa,断裂伸长率可达709.82%,全切修复后分别可达16.90 MPa,630.32%,修复效率为89%,仍具有使用价值。样条全切修复后树脂经粉碎后可以重新加工成完整的聚氨酯膜使用,具备优异的可重复加工性。并且可实现加热及紫外光下的双重修复功能,其中LPU-2在75℃时10 min即可完成划痕修复。

Dynamic Analysis of Single Pile in Liquefied Soils Considered as Newtonian Fluid

Case histories have shown that the liquefaction-induced soil lateral spreading is one of the main causes of damage to pile foundations subjected to seismic loading. Post-liquefaction soil behaves similarly to a viscous fluid. This study investigated the effect of soil lateral spreading on a single pile based on fluid mechanics in which the liquefied soils were treated as Newtonian fluids. A numerical simulation on a single pile embedded in a fully saturated sandy foundation was conducted and compared with shake table tests. The lateral flow effect and the effect of shear strain rate were discussed. After liquefaction, the acceleration of the foundation shows that there are no obvious spikes and finally reaches a stable state. The presented method can predict the pile response better than p-y curve method. A parametric study was performed to explore the effect of several influence factors on pile behaviors. The results show that the pile head displacement decreases and the maximum bending moment at pile bottom increases with the increase of bending stiffness. With the same pile bending stiffness, the displacement and bending moment of pile increase with the increase of soil viscosity and acceleration amplitude.

Estimation of inbreeding and identification of regions under heavy selection based on runs of homozygosity in a Large White pig population

Background: Runs of homozygosity(ROHs) are homozygous segments of the genome where the two haplotypes inherited from the parents are identical. The current availability of genotypes for a very large number of single nucleotide polymorphisms(SNPs) is leading to more accurate characterization of ROHs in the whole genome. Here,we investigated the occurrence and distribution of ROHs in 3,692 Large White pigs and compared estimates of inbreeding coefficients calculated based on ROHs(FROH), homozygosity(FHOM), genomic relationship matrix(FGRM)and pedigree(FPED). Furthermore, we identified genomic regions with high ROH frequencies and annotated their candidate genes.Results: In total, 176,182 ROHs were identified from 3,569 animals, and all individuals displayed at least one ROH longer than 1 Mb. The ROHs identified were unevenly distributed on the autosomes. The highest and lowest coverages of Sus scrofa chromosomes(SSC) by ROH were on SSC14 and SSC13, respectively. The highest pairwise correlation among the different inbreeding coefficient estimates was 0.95 between FROH_totaland FHOM, while the lowest was-0.083 between FGRMand FPED. The correlations between FPEDand FROHusing four classes of ROH lengths ranged from 0.18 to 0.37 and increased with increasing ROH length, except for ROH > 10 Mb. Twelve ROH islands were located on four chromosomes(SSC1, 4, 6 and 14). These ROH islands harboured genes associated with reproduction, muscular development, fat deposition and adaptation, such as SIRT1, MYPN, SETDB1 and PSMD4.Conclusion: FROHcan be used to accurately assess individual inbreeding levels compared to other inbreeding coefficient estimators. In the absence of pedigree records, FROHcan provide an alternative to inbreeding estimates.Our findings can be used not only to effectively increase the response to selection by appropriately managing the rate of inbreeding and minimizing the negative effects of inbreeding depression but also to help detect genomic regions with an effect on traits under selection.

Genome-wide identification of RNA editing in seven porcine tissues by matched DNA and RNA high-throughput sequencing

Background: RNA editing is a co/posttranscriptional modification mechanism that increases the diversity of transcripts, with potential functional consequences. The advent of next-generation sequencing technologies has enabled the identification of RNA edits at unprecedented throughput and resolution. However, our knowledge of RNA editing in swine is still limited.Results: Here, we utilized RES-Scanner to identify RNA editing sites in the brain, subcutaneous fat, heart, liver,muscle, lung and ovary in three 180-day-old Large White gilts based on matched strand-specific RNA sequencing and whole-genome resequencing datasets. In total, we identified 74863 editing sites, and 92.1% of these sites caused adenosine-to-guanosine(A-to-G) conversion. Most A-to-G sites were located in noncoding regions and generally had low editing levels. In total, 151 A-to-G sites were detected in coding regions(CDS), including 94 sites that could lead to nonsynonymous amino acid changes. We provide further evidence supporting a previous observation that pig transcriptomes are highly editable at PRE-1 elements. The number of A-to-G editing sites ranged from 4155(muscle) to 25001(brain) across the seven tissues. The expression levels of the ADAR enzymes could explain some but not all of this variation across tissues. The functional analysis of the genes with tissuespecific editing sites in each tissue revealed that RNA editing might play important roles in tissue function.Specifically, more pathways showed significant enrichment in the fat and liver than in other tissues, while no pathway was enriched in the muscle.Conclusions: This study identified a total of 74863 nonredundant RNA editing sites in seven tissues and revealed the potential importance of RNA editing in tissue function. Our findings largely extend the porcine editome and enhance our understanding of RNA editing in swine.

The landscape of chromatin accessibility in skeletal muscle during embryonic development in pigs

Background:The development of skeletal muscle in pigs during the embryonic stage is precisely regulated by transcriptional mechanisms,which depend on chromatin accessibility.However,how chromatin accessibility plays a regulatory role during embryonic skeletal muscle development in pigs has not been reported.To gain insight into the landscape of chromatin accessibility and the associated genome-wide transcriptome during embryonic muscle development,we performed ATAC-seq and RNA-seq analyses of skeletal muscle from pig embryos at 45,70 and 100 days post coitus(dpc).Results:In total,21,638,35,447 and 60,181 unique regions(or peaks)were found across the embryos at 45 dpc(LW45),70 dpc(LW70)and 100 dpc(LW100),respectively.More than 91%of the peaks were annotated within−1 kb to 100 bp of transcription start sites(TSSs).First,widespread increases in specific accessible chromatin regions(ACRs)from embryos at 45 to 100 dpc suggested that the regulatory mechanisms became increasingly complicated during embryonic development.Second,the findings from integrated ATAC-seq and RNA-seq analyses showed that not only the numbers but also the intensities of ACRs could control the expression of associated genes.Moreover,the motif screening of stage-specific ACRs revealed some transcription factors that regulate muscle developmentrelated genes,such as MyoG,Mef2c,and Mef2d.Several potential transcriptional repressors,including E2F6,OTX2 and CTCF,were identified among the genes that exhibited different regulation trends between the ATAC-seq and RNA-seq data.Conclusions:This work indicates that chromatin accessibility plays an important regulatory role in the embryonic muscle development of pigs and regulates the temporal and spatial expression patterns of key genes in muscle development by influencing the binding of transcription factors.Our results contribute to a better understanding of the regulatory dynamics of genes involved in pig embryonic skeletal muscle development.

Geochemical characteristics of Early Cretaceous source rocks in Boli Basin

The Early Cretaceous deposits are composed of important source rocks in Boli Basin. The types of the source rocks include black mudstones and coal (with carbonaceous mudstone). By the organic geochemical analysis methods, the authors discussed the organic petrological characters, abundance of organic matter, degree of maturity and the type of source rocks. The main micro-component of black mudstone is exinite or vitrinite, and the content of vitrinite is high in coal. The weathering of the outcrop is very serious. The abundance of organic matter in source rock reaches the poor to better rank. The major kerogens in mudstone are type-Ⅲ, type-Ⅱ 2 and some type-Ⅱ 1; the organic type of coal is type-Ⅲ. The thermal evolution of the source rocks in every structural unit is very different, from low-maturity to over-maturity. The depositional environment is reductive, which is good for the preservation of organic matter. The organic matter in source rocks is mainly from aquatic organisms and terrigenous input.

Activation of iridium site by anchoring ruthenium atoms on defects for efficient anodic catalyst in polymer electrolyte membrane water electrolyzers

1.Introduction Hydrogen is an ideal energy carrier to tackle the energy crisis and greenhouse effect,because of its high energy density and low emission.The production,storage and transportation of hydrogen are key factors to the practical application of hydrogen energy.As the scientific and technological understanding of the electrochemical devices was advancing in the past few decades,water electrolyzers based on the proton exchange membrane (PEM) have attracted much focus for its huge potential on the production of hydrogen via water splitting.PEM electrolyzers use perfluorinated sulfonic acid (PFSA) based membranes as the electrolyte.

昆仑山青海片区鸟类群落多样性格局及其驱动因素

昆仑山脉独特的地理位置和气候条件孕育了诸多适应高海拔、寒旱气候的特有鸟类物种。为揭示昆仑山青海片区内鸟类群落在不同季节和海拔梯度的多样性分布格局及环境驱动因素,我们于2021年12月(冬季)和2022年7月(夏季)在当地选取102个样方,通过样线法对鸟类多样性进行了本底调查,并选取了不同的气候和人为干扰因子拟合多样性指数与因子之间的非线性关系。结果表明:(1)昆仑山青海片区野外调查过程中共记录到鸟类14目31科59属87种,其中国家一级重点保护野生鸟类5种,国家二级重点保护野生鸟类11种,该地区新分布鸟类8种;(2)鸟类群落多样性分布格局分析结果显示,夏季多样性显著高于冬季,草甸和草原生境的鸟类群落多样性显著高于其他生境,冬夏季鸟类群落多样性指数与海拔梯度变化趋势均呈单峰型;(3)气候因素驱动鸟类多样性指数呈现季节性差异,最冷季度降水量对夏季物种丰富度指数影响最大,冬季为年降水量;此外,等温性和温度季节性对冬夏季Shannon-Wiener多样性指数和Simpson多样性指数影响最大。本研究揭示了水资源和稳定的气候对昆仑山青海片区鸟类群落多样性的重要性,为昆仑山青海片区鸟类资源保护与管理以及未来国家公园的规划建设提供了数据支持。

Effects of ex situ conservation on diversity and function of the gut microbiota of the Tibetan wild ass(Equus kiang)

Ex situ conservation is the main method for the protection of endangered wildlife.To explore the effect of ex situ conservation on the gut microbiota of the kiang(Equus kiang),metagenomic sequencing combined with bioinformatics analysis was used to investigate the composition and function of the gut microbiota of the kiang.The results showed that ex situ conservation not only protected wildlife,but also affected the composition and function of gut microbiota,as well as the health of animals.In the zoo,the ratio of the relative abundance of Firmicutes to that of Bacteroidetes(F/B)is higher,clusters of potentially pathogenic bacteria(such as Catonella,Catonella,and Mycoplasma)are more numerous,the abundance of resistance genes is higher,and the abundance of metabolic functions is increased.The dynamic changes of the gut microbiota also played an important role in the nutritional absorption,energy metabolism,and environmental adaptation of the kiang.Improving the rearing environment and increasing food diversity play important roles for increasing the diversity of gut microbiota,reducing the spread of potentially pathogenic bacteria,and reducing diseases.In the wild,especially in winter and in food-deficient areas,food supplementation can enhance the gut microbial homeostasis of wild animals and reduce the impact of crises.In depth studies of the gut microbial function of wildlife have important implications for improving ex situ conservation.