与45钢对摩材料干摩擦条件下的摩擦学性能

为选择与45钢对摩的摩擦副材料以适应干摩擦苛刻工况,采用RTEC多功能摩擦试验机,对超高分子量聚乙烯(UHMWPE)、改性聚醚醚酮树脂(改性PEEK)、浸渍呋喃树脂碳石墨(M120K)和浸渍巴氏合金碳石墨(M120B)4种配副材料的摩擦学性能进行测试,并利用扫描电子显微镜对磨损表面进行观察和分析,从微观角度揭示了4种材料的摩擦磨损机理。结果表明,随着载荷和转速的增加,平均摩擦系数大致呈现出M120B<UHMWPE<改性PEEK<M120K的规律,磨损率则大致呈现出M120B<改性PEEK<M120K<UHMWPE的规律。当载荷增大时,UHMWPE和M120K由磨粒磨损逐渐转变为粘着磨损;改性PEEK以粘着磨损为主并伴随轻微的磨粒磨损;M120B表现出磨粒磨损与粘着磨损共存的形式。当转速增大时,UHMWPE和M120B以磨粒磨损为主并伴随轻微的粘着磨损;改性PEEK和M120K以粘着磨损为主并伴随轻微的磨粒磨损。

Straw return increases crop production by improving soil organic carbon sequestration and soil aggregation in a long-term wheat-cotton cropping system

Straw return is a promising strategy for managing soil organic carbon(SOC)and improving yield stability.However,the optimal straw return strategy for sustainable crop production in the wheat(Triticum aestivum L.)-cotton(Gossypium hirsutum L.)cropping system remains uncertain.The objective of this study was to quantify the long-term(10 years)impact of carbon(C)input on SOC sequestration,soil aggregation and crop yields in a wheat-cotton cropping system in the Yangtze River Valley,China.Five treatments were arranged with a single-factor randomized design as follows:no straw return(Control),return of wheat straw only(Wt),return of cotton straw only(Ct),return of 50%wheat and 50%cotton straw(Wh-Ch)and return of 100%wheat and 100%cotton straw(Wt-Ct).In comparison to the Control,the SOC content increased by 8.4 to 20.2%under straw return.A significant linear positive correlation between SOC sequestration and C input(1.42-7.19 Mg ha^(−1)yr^(−1))(P<0.05)was detected.The percentages of aggregates of sizes>2 and 1-2 mm at the 0-20 cm soil depth were also significantly elevated under straw return,with the greatest increase of the aggregate stability in the Wt-Ct treatment(28.1%).The average wheat yields increased by 12.4-36.0%and cotton yields increased by 29.4-73.7%,and significantly linear positive correlations were also detected between C input and the yields of wheat and cotton.The average sustainable yield index(SYI)reached a maximum value of 0.69 when the C input was 7.08 Mg ha^(−1)yr^(−1),which was close to the maximum value(SYI of 0.69,C input of 7.19 Mg ha^(−1)yr^(-1))in the Wt-Ct treatment.Overall,the return of both wheat and cotton straw was the best strategy for improving SOC sequestration,soil aggregation,yields and their sustainability in the wheat-cotton rotation system.

Electrochemical Hydrogen Charging on Corrosion Behavior of Ti-6Al-4V Alloy in Artificial Seawater

This study employs advanced electrochemical and surface characterization techniques to investigate the impact of electrochemical hydrogen charging on the corrosion behavior and surface film of the Ti-6Al-4V alloy.The findings revealed the formation ofγ-TiH andδ-TiH_(2) hydrides in the alloy after hydrogen charging.Prolonging hydrogen charging resulted in more significant degradation of the alloy microstructure,leading to deteriorated protectiveness of the surface film.This trend was further confirmed by the electrochemical measurements,which showed that the corrosion resistance of the alloy progressively worsened as the hydrogen charging time was increased.Consequently,this work provides valuable insights into the mechanisms underlying the corrosion of Ti-6Al-4V alloy under hydrogen charging conditions.

Meiotic nuclear divisions 1 suppresses the proliferation and invasion of pancreatic cancer cells via regulating H2A.X variant histone

Introduction:Among all malignant tumors of the digestive system,pancreatic carcinoma exhibits the highest mortality rate.Currently,prevention and effective treatment are urgent issues that need to be addressed.Methods:The study focused on meiotic nuclear divisions 1(MND1),integrating data from the Gene Expression Profiling Interactive Analysis(GEPIA)database with prognostic survival analysis.Simultaneously,experiments at cellular level were employed to demonstrate the effect of MND1 on the proliferation and migration of PC.The small-molecule inhibitor of MND1 was used to suppress the migration of PC cells by knocking down MND1 using small interfering RNA(siRNA)in Patu-8988 and Panc1 cell lines.Results:The results of Cell Counting Kit-8 indicated that the suppression of MND1 resulted in a decrease in cell proliferation.Wound healing and Transwell assays revealed that MND1 knockdown reduced cell migration and invasion.Flow cytometry revealed that inhibiting MND1 hindered the cell cycle.Furthermore,MND1 could stimulate the proliferation,migration,and invasion of Patu-8988 and Panc1 cells by increasing the expression of MND1.Notably,MND1 had a positive effect on H2AFX expression in PC cells.Elevated MND1 expression suggests the low overall survival rate of individuals diagnosed with PC.Conclusion:These findings suggest that MND1 has the potential to be a gene with the ability to accurately diagnose and treat PC.

Boundedness for Multilinear Operators of Pseudo-Differential Operators

In this paper, we establish a sharp function estimate for the multilinear integral operators associated to the pseudo-differential operators. As the application, we obtain the Lp (1 p norm inequalities for the multilinear operators.

Integrated analysis of transcriptomic and proteomic data from tree peony(P.ostii)seeds reveals key developmental stages and candidate genes related to oil biosynthesis and fatty acid metabolism

Tree peony(Paeonia section Moutan DC.)seeds are an excellent source of beneficial natural compounds that promote health,and they contain high levels of alpha-linolenic acid(ALA).In recent years,tree peony has been emerging as an oil crop.Therefore,combined analysis of the transcriptome and proteome of tree peony(P.ostii)seeds at 25,32,39,53,67,81,88,95,and 109 days after pollination(DAP)was conducted to better understand the transcriptional and translational regulation of seed development and oil biosynthesis.A total of 38,482 unigenes and 2841 proteins were identified.A total of 26,912 differentially expressed genes(DEGs)and 592 differentially expressed proteins(DEPs)were clustered into three groups corresponding to the rapid growth,seed inclusion enrichment and conversion,and late dehydration and mature stages of seed development.Fifteen lipid metabolism pathways were identified at both the transcriptome and proteome levels.Pathway enrichment analysis revealed that a period of rapid fatty acid biosynthesis occurred at 53–88 DAP.Furthermore,211 genes and 35 proteins associated with the fatty acid metabolism pathway,63 genes and 11 proteins associated with the biosynthesis of unsaturated fatty acids(UFAs),and 115 genes and 24 proteins associated with ALA metabolism were identified.Phylogenetic analysis revealed that 16 putative fatty acid desaturase(FAD)-encoding genes clustered into four FAD groups,eight of which exhibited the highest expression at 53 DAP,suggesting that they play an important role in ALA accumulation.RT-qPCR analysis indicated that the temporal expression patterns of oil biosynthesis genes were largely similar to the RNA-seq results.The expression patterns of fatty acid metabolism-and seed development-related proteins determined by MRM were also highly consistent with the results obtained in the proteomic analysis.Correlation analysis indicated significant differences in the number and abundance of DEGs and DEPs but a high level of consistency in expression patterns and metabolic pathways.The results of the present study represent the first combined transcriptomic and proteomic analysis of tree peony seeds and provide insight into tree peony seed development and oil accumulation.

The R2R3-MYB transcription factor GhMYB1a regulates flavonol and anthocyanin accumulation in Gerbera hybrida

Anthocyanins and flavonols have vital roles in flower coloration,plant development,and defense.Because anthocyanins and flavonols share the same subcellular localization and common biosynthetic substrates,these pathways may compete for substrates.However,the mechanism regulating this potential competition remains unclear.Here,we identified GhMYB1a,an R2R3-MYB transcription factor involved in the regulation of anthocyanin and flavonol accumulation in gerbera(Gerbera hybrida).GhMYB1a shares high sequence similarity with that of other characterized regulators of flavonol biosynthesis.In addition,GhMYB1a is also phylogenetically grouped with these proteins.The overexpression of GhMYB1a in gerbera and tobacco(Nicotiana tabacum)resulted in decreased anthocyanin accumulation and increased accumulation of flavonols by upregulating the structural genes involved in flavonol biosynthesis.We further found that GhMYB1a functions as a homodimer instead of interacting with basic helix-loop-helix cofactors.These results suggest that GhMYB1a is involved in regulating the anthocyanin and flavonol metabolic pathways through precise regulation of gene expression.The functional characterization of GhMYB1a provides insight into the biosynthesis and regulation of flavonols and anthocyanins.

Modulation recognition of MIMO radar signal based on joint HOS and SNR algorithm

This paper presents a joint high order statistics(HOS)and signal-to-noise ratio(SNR) algorithm for the recognition of multiple-input multiple-output(MIMO) radar signal without a priori knowledge of the signal parameters. This method is capable of recognizing the MIMO radar signal as well as discriminating it from single-carrier signal adopted by conventional radar. Meanwhile,the sub-carrier number of the none-coding MIMO radar signal is estimated. Extensive simulations are carried out in different operating conditions. Simulation results prove the feasibility and indicate that the recognition probability could reach over 90% when the value of SNR is above 0 dB.

Expert consensus on early childhood caries management

Early childhood caries(ECC)is a significant chronic disease of childhood and a rising public health burden worldwide.ECC may cause a higher risk of new caries lesions in both primary and permanent dentition,affecting lifelong oral health.The occurrence of ECC has been closely related to the core microbiome change in the oral cavity,which may be influenced by diet habits,oral health management,fluoride use,and dental manipulations.So,it is essential to improve parental oral health and awareness of health care,to establish a dental home at the early stage of childhood,and make an individualized caries management plan.Dental interventions according to the minimally invasive concept should be carried out to treat dental caries.This expert consensus mainly discusses the etiology of ECC,caries-risk assessment of children,prevention and treatment plan of ECC,aiming to achieve lifelong oral health.

Genome-level diversification of eight ancient tea populations in the Guizhou and Yunnan regions identifies candidate genes for core agronomic traits

The ancient tea plant,as a precious natural resource and source of tea plant genetic diversity,is of great value for studying the evolutionary mechanism,diversification,and domestication of plants.The overall genetic diversity among ancient tea plants and the genetic changes that occurred during natural selection remain poorly understood.Here,we report the genome resequencing of eight different groups consisting of 120 ancient tea plants:six groups from Guizhou Province and two groups from Yunnan Province.Based on the 8,082,370 identified high-quality SNPs,we constructed phylogenetic relationships,assessed population structure,and performed genome-wide association studies(GWAS).Our phylogenetic analysis showed that the 120 ancient tea plants were mainly clustered into three groups and five single branches,which is consistent with the results of principal component analysis(PCA).Ancient tea plants were further divided into seven subpopulations based on genetic structure analysis.Moreover,it was found that the variation in ancient tea plants was not reduced by pressure from the external natural environment or artificial breeding(nonsynonymous/synonymous=1.05).By integrating GWAS,selection signals,and gene function prediction,four candidate genes were significantly associated with three leaf traits,and two candidate genes were significantly associated with plant type.These candidate genes can be used for further functional characterization and genetic improvement of tea plants.

Identification and characterization of tomato gibberellin 2-oxidases (GA2oxs) and effects of fruit-specific SlGA2ox1 overexpression on fruit and seed growth and development

Gibberellins(GAs)play a crucial role in growth and development of the tomato fruit.Previously published studies focusing on the effect of GAs on tomato fruits used chemical treatments,constitutive overexpression or silencing of GA biosynthetic and catabolic genes globally throughout the plant.Fruit-specific overexpression of GA catabolic enzyme genes GA2-oxidases(GA2oxs),however,may provide an alternative method to study the role of endogenous GAs on the fruit development.In this study,we have identified 11 SlGA2ox proteins in tomato that are classified into three subgroups.Motif analysis and multiple sequence alignments have demonstrated that all SlGA2oxs,except SlGA2ox10,have similar motif compositions and high-sequence conservation.Quantitative reverse transcription-PCR analysis has showed that SlGA2oxs exhibit differential expression patterns in tomato fruits at different developmental stages.When the fruit-specific promoter TFM7 was used to control the expression of SlGA2ox1,we observed no changes in growth and development of vegetative organs.However,fruit weight,seed number and germination rate were significantly affected.We also treated tomato fruits with GA biosynthesis inhibitor and observed phenotypes similar to those of the transgenic fruits.Furthermore,we have demonstrated that expression of cell expansion and GA responsive genes were downregulated in transgenic tomato fruits,supporting that overexpression of the SlGA2ox1 leads to reduction in endogenous GAs.This study provides additional evidence that endogenous GAs and the SlGA2ox1 gene play an important role in controlling on fruit weight,seed development and germination in tomato plant.

Early diagenesis of redox-sensitive trace metals in the northern Okinawa Trough

The early diagenesis processes of several redox-sensitive trace metals(RSMs)(Mo, U and V) were studied with several short sediment cores(~25 cm) collected in the northern Okinawa Trough(OT). Pore water vertical profiles indicated that the sedimentary environments in all cores were between oxic and suboxic, not yet reaching anoxic sulfidic conditions. The recycling process of Mo in sediments was clearly associated with Mn and yielded little authigenic accumulation, while U showed a downcore increase in sediment and its authigenic mass accumulation rate(MAR) was estimated to be ~23% of the Changjiang(Yangtze) and Huanghe(Yellow) riverine flux. Benthic diffusive fluxes and MAR were calculated and the comparison of them showed that U and V fluxes matched relatively well both in direction and in magnitude, implying that diffusion processes at the sedimentwater interface is the dominant process controlling the remobilization or burial of V and U in northern OT. This work provided a systematic study(both in pore water and solid phase) on the RSMs geochemical behaviors during early diagenesis process, yielding a quantitative assessment of the remobilization or burial fluxes of the RSMs in northern OT. Such studies are in general lacking in the coastal margin of Northwest Pacific Ocean.

Evolution and roles of cytokinin genes in angiosperms 1:Do ancient IPTs play housekeeping while non-ancient IPTs play regulatory roles?

Isopentenyltransferase(IPT)genes,including those encoding ATP/ADP-IPTs and tRNA-IPTs,control the rate-limiting steps of the biosynthesis of N6-(Δ2-isopentenyl)adenine(iP)-type and trans-zeatin(tZ)-type cytokinins and cis-zeatin(cZ)-type cytokinins,respectively.However,the evolution and roles of these IPTs in angiosperms are not well understood.Here,we report comprehensive analyses of the origins,evolution,expression patterns,and possible roles of ATP/ADP-IPTs and tRNA-IPTs in angiosperms.We found that Class I and II tRNA-IPTs likely coexisted in the last common ancestor of eukaryotes,while ATP/ADP-IPTs likely originated from a Class II tRNA-IPT before the divergence of angiosperms.tRNA-IPTs are conservatively retained as 2–3 copies,but ATP/ADP-IPTs exhibit considerable expansion and diversification.Additionally,tRNA-IPTs are constitutively expressed throughout the plant,whereas the expression of ATP/ADP-IPTs is tissue-specific and rapidly downregulated by abiotic stresses.Furthermore,previous studies and our present study indicate that ATP/ADP-IPTs and their products,iPs/tZs,may regulate responses to environmental stresses and organ development in angiosperms.We therefore hypothesize that tRNA-IPTs and the associated cZs play a housekeeping role,whereas ATP/ADP-IPTs and the associated iP/tZ-type cytokinins play regulatory roles in organ development and stress responses in angiosperms,which echoes the conclusions and hypothesis presented in the accompanying study by Wang,X.et al Evolution and roles of cytokinin genes in angiosperms 2:Do ancient CKXs play housekeeping roles while non-ancient CKXs play regulatory roles?Hortic Res https://doi.org/10.1038/s41438-020-0246-z.

Evolution and roles of cytokinin genes in angiosperms 2:Do ancient CKXs play housekeeping roles while non-ancient CKXs play regulatory roles?

Cytokinin oxidase/dehydrogenase(CKX)is a key enzyme responsible for the degradation of endogenous cytokinins.However,the origins and roles of CKX genes in angiosperm evolution remain unclear.Based on comprehensive bioinformatic and transgenic plant analyses,we demonstrate that the CKXs of land plants most likely originated from an ancient chlamydial endosymbiont during primary endosymbiosis.We refer to the CKXs retaining evolutionarily ancient characteristics as“ancient CKXs”and those that have expanded and functionally diverged in angiosperms as“non-ancient CKXs”.We show that the expression of some non-ancient CKXs is rapidly inducible within 15 min upon the dehydration of Arabidopsis,while the ancient CKX(AtCKX7)is not drought responsive.Tobacco plants overexpressing a non-ancient CKX display improved oxidative and drought tolerance and root growth.Previous mutant studies have shown that non-ancient CKXs regulate organ development,particularly that of flowers.Furthermore,ancient CKXs preferentially degrade cis-zeatin(cZ)-type cytokinins,while non-ancient CKXs preferentially target N6-(Δ2-isopentenyl)adenines(iPs)and trans-zeatins(tZs).Based on the results of this work,an accompanying study(Wang et al.https://doi.org/10.1038/s41438-019-0211-x)and previous studies,we hypothesize that non-ancient CKXs and their preferred substrates of iP/tZ-type cytokinins regulate angiosperm organ development and environmental stress responses,while ancient CKXs and their preferred substrates of cZs play a housekeeping role,which echoes the conclusions and hypothesis described in the accompanying report(Wang,X.et al.Evolution and roles of cytokinin genes in angiosperms 1:Doancient IPTs play housekeeping while non-ancient IPTs play regulatory roles?Hortic Res 7,(2020).https://doi.org/10.1038/s41438-019-0211-x).

ACGA Algorithm of Solving Weapon - Target Assignment Problem

Weapon Target Assignment is not only an important issue to use firepower, but also an important operational decision-making problem. As new intelligent algorithms, Genetic algorithm and ant colony algorithm are applied to solve Weapons-Target Assignment Problem. This paper introduces the Weapon-Target Assignment (WTA) and the mathematical model, and proposes ACGA algorithm which is the integration of genetic algorithm and ant colony algorithm then use ACGA algorithm to solve the Weapon-Target Assignment Problem. Calculations show that: when ACGA algorithm is used to solve Weapon – Target Assignment Problem, it has fast convergence and high accuracy.

2023年中国植物科学重要研究进展

2023年中国科学家在植物科学主流期刊发表的论文数量相比2022年大幅提高,在柱头受体调控十字花科种内和种间生殖隔离,叶绿体TOC-TIC超级复合物结构,作物高产、耐逆及抗病机制,葡萄和柑橘属植物的起源和传播,现代玉米、谷子和马铃薯种质资源演化等方面取得了重要研究进展。其中,“农作物耐盐碱机制解析及应用”和“新方法实现单碱基到超大片段DNA精准操纵”入选2023年度中国科学十大进展,“植物远缘杂交过程中‘花粉蒙导效应’的分子机制”入选2023年度中国生命科学十大进展。该文总结了2023年度我国植物科学研究取得的成果,并简要介绍了30项有代表性的重要进展,梳理了植物科学研究中所使用的实验材料,以帮助读者了解我国植物科学的发展态势,进而思考如何更好地开展下阶段研究和服务国家重大战略需求。

Evaluation on Fabrication and Properties of Composite Polyurethane Coatings with Wollastonite Partially Substituting for Rutile Titanium Dioxide

This study aims to prepare a composite polyurethane coating through a facile synthesis process. Titanium dioxide, which is a component of the prepared hydroxyl acrylic resin polyurethane varnish, was partially substituted by wollastonite, and an optimal substitution ratio was obtained. Analyses based on scanning electron microscope, powder X-ray diffraction, and Raman scattering measurements demonstrated that the addition of wollastonite caused nearly no change in the basic structure of the coating. Coating with a substitution ratio of 25% showed high thermal stability, good cover effect, considerable moisture-proof and water resistance ability, great acidic and basic resistance, and improved performance and hardness in performance tests. Furthermore, the production cost was reduced significantly at this substitution ratio.

Cloning, Sequence Analysis, and Prokaryotic Expression of the Porcine DECR1 Gene

2,4-dienoyl-CoA reductase 1 (DECR1) is the key rate-limiting enzyme in the metabolism of polyunsaturated fatty acids. Although this protein has been studied in a variety of mammals, its role in porcine is yet to be fully elucidated. However, it is a candidate determinant/indicator of meat quality, growth traits, and carcass quality. Here, we employed RT-PCR and rapid amplification of cDNA ends (RACE) analysis to amplify the full-length cDNA of DECR1 from Mashen pig liver, and cloned it into the expression vector pET-32a+. After confirmation by sequencing and restriction analysis, the recombinant plasmid was transformed into E. coli BL21 cells. The cDNA of pig DECR1 contained 2,352 nucleotides, including a 987 bp open reading frame flanked by a 53 bp 5′-untranslated region (UTR) and a 1,312 bp 3′-UTR. The pig DECR1 coding sequence encoded 328 amino acid residues, which shared 99%, 88%, 87%, 87%, 87%, 87%, and 83% identity with those of Sus scrofa (predicted), Bos taurus, Homo sapiens, Macaca mulatta, Pan troglodytes, Equus caballus, Canis, and Mus musculus, respectively. SDS-PAGE analysis revealed that the recombinant protein was expressed and that the expression level reached its highest level after 4 h induction. Western blot analysis indicated that the molecular weight of the expressed protein was the same as that predicted, approximately 35 kDa. Collectively these data provide the basis for further studies into the physiological functions and molecular mechanisms of the pig DECR1 gene.

Hydrodynamics of Continuous Spiral Dryer with Rotatory Conical Sleeves: Experiments versus CFD Simulations

In this study, a continuous and airtight twinspiral dryer was developed in accordance with the characteristics and challenges in the process of disposing polysilicon slurry. Computational fluid dynamics(CFD)simulations were used to investigate the flow field in the rotating twin-spiral continuous dryer and an original discrete phase model was also elaborated to compare with the cold-modeling experimental results. The corresponding flow field was obtained using the available inlet velocity of 0.05-0.3 m/s and the rotational speed of the inner cone of 12-44 r/min, the residence time distribution, and tracked particles trajectory. Results showed that the residence time of the tracer particles in the cone cylinder was about 15.8-25.4% of the time spent out of it, and the particle's residence time was much shorter in contrast to the rotational speed and inlet velocity. The external ribbon had a larger influence on the fluid, thereby leading to a larger velocity in the region outside the cone compared to that in the region inside the cone. In addition, the appearance of the vortex and boundary layer separation at the back of the ribbon and the spoke bar had secondary diversion effects on the fluid. Furthermore, the inlet velocity had little influence on the flow field while the rotational speed of the cone greatly affected the flow field. Hence, the CFD simulations showed good agreement with the experimental results.

Mechanisms of Steatosis-Derived Hepatocarcinogenesis:Lessons from HCV Core Gene Transgenic Mice

Hepatitis C virus(HCV)is a major cause of chronic hepatitis,liver cirrhosis,and hepatocellular carcinoma(HCC)worldwide.Among the structural proteins of HCV,the HCV core protein has the ability to regulate gene transcription,lipid metabolism,cell proliferation,apoptosis,and autophagy,all of which are closely related to the development of HCC.Transgenic mice carrying the HCV core gene exhibited age-dependent insulin resistance,hepatic steatosis,and HCC that resembled the clinical characteristics of chronic hepatitis C patients.Several dietary modifications,including calorie restriction and diets rich in saturated fatty acids,trans fatty acids,or cholesterol,were found to influence hepatic steatogenesis and tumorigenesis in HCV core gene transgenic mice.These strategies modulated hepatocellular stress and proliferation,in addition to hepatic fibrotic processes and the microenvironment,thereby corroborating a close interconnection between dietary habits and steatosis-related hepatocarcinogenesis.In this review,we summarize the findings obtained from mouse models transgenic for the HCV genome,with a special focus on HCV core gene transgenic mice,and discuss the mechanisms of steatogenesis and hepatocarcinogenesis induced by the HCV core protein and the impact of dietary habits on steatosis-derived HCC development.