Stress-assisted corrosion mechanism of 3Ni steel by using gradient boosting decision tree machining learning method

Traditional 3Ni weathering steel cannot completely meet the requirements for offshore engineering development,resulting in the design of novel 3Ni steel with the addition of microalloy elements such as Mn or Nb for strength enhancement becoming a trend.The stress-assisted corrosion behavior of a novel designed high-strength 3Ni steel was investigated in the current study using the corrosion big data method.The information on the corrosion process was recorded using the galvanic corrosion current monitoring method.The gradi-ent boosting decision tree(GBDT)machine learning method was used to mine the corrosion mechanism,and the importance of the struc-ture factor was investigated.Field exposure tests were conducted to verify the calculated results using the GBDT method.Results indic-ated that the GBDT method can be effectively used to study the influence of structural factors on the corrosion process of 3Ni steel.Dif-ferent mechanisms for the addition of Mn and Cu to the stress-assisted corrosion of 3Ni steel suggested that Mn and Cu have no obvious effect on the corrosion rate of non-stressed 3Ni steel during the early stage of corrosion.When the corrosion reached a stable state,the in-crease in Mn element content increased the corrosion rate of 3Ni steel,while Cu reduced this rate.In the presence of stress,the increase in Mn element content and Cu addition can inhibit the corrosion process.The corrosion law of outdoor-exposed 3Ni steel is consistent with the law based on corrosion big data technology,verifying the reliability of the big data evaluation method and data prediction model selection.

WPA1 encodes a vWA domain protein that regulates wheat plant architecture

Plant height,spike,leaf,stem and grain morphologies are key components of plant architecture and related to wheat yield.A wheat(Triticum aestivum L.)mutant,wpa1,displaying temperaturedependent pleiotropic developmental anomalies,was isolated.The WPA1 gene,encoding a von Willebrand factor type A(vWA)domain protein,was located on chromosome arm 7DS and isolated by map-based cloning.The functionality of WPA1 was validated by multiple independent EMS-induced mutants and gene editing.Phylogenetic analysis revealed that WPA1 is monocotyledon-specific in higher plants.The identification of WPA1 provides opportunity to study the temperature regulated wheat development and grain yield.

Advances in memristor based artificial neuron fabrication-materials,models,and applications

Spiking neural network(SNN),widely known as the third-generation neural network,has been frequently investigated due to its excellent spatiotemporal information processing capability,high biological plausibility,and low energy consumption characteristics.Analogous to the working mechanism of human brain,the SNN system transmits information through the spiking action of neurons.Therefore,artificial neurons are critical building blocks for constructing SNN in hardware.Memristors are drawing growing attention due to low consumption,high speed,and nonlinearity characteristics,which are recently introduced to mimic the functions of biological neurons.Researchers have proposed multifarious memristive materials including organic materials,inorganic materials,or even two-dimensional materials.Taking advantage of the unique electrical behavior of these materials,several neuron models are successfully implemented,such as Hodgkin–Huxley model,leaky integrate-and-fire model and integrate-and-fire model.In this review,the recent reports of artificial neurons based on memristive devices are discussed.In addition,we highlight the models and applications through combining artificial neuronal devices with sensors or other electronic devices.Finally,the future challenges and outlooks of memristor-based artificial neurons are discussed,and the development of hardware implementation of brain-like intelligence system based on SNN is also prospected.

A novel integrated microfluidic chip for on-demand electrostatic droplet charging and sorting

On-demand droplet sorting is extensively applied for the efficient manipulation and genome-wide analysis of individual cells.However,state-of-the-art microfluidic chips for droplet sorting still suffer from low sorting speeds,sample loss,and labor-intensive preparation procedures.Here,we demonstrate the development of a novel microfluidic chip that integrates droplet generation,on-demand electrostatic droplet charging,and high-throughput sorting.The charging electrode is a copper wire buried above the nozzle of the microchannel,and the deflecting electrode is the phosphate buffered saline in the microchannel,which greatly simplifies the structure and fabrication process of the chip.Moreover,this chip is capable of high-frequency droplet generation and sorting,with a frequency of 11.757 kHz in the drop state.The chip completes the selective charging process via electrostatic induction during droplet generation.On-demand charged microdroplets can arbitrarilymove to specific exit channels in a three-dimensional(3D)-deflected electric field,which can be controlled according to user requirements,and the flux of droplet deflection is thereby significantly enhanced.Furthermore,a lossless modification strategy is presented to improve the accuracy of droplet deflection or harvest rate from 97.49% to 99.38% by monitoring the frequency of droplet generation in real time and feeding it back to the charging signal.This chip has great potential for quantitative processing and analysis of single cells for elucidating cell-to-cell variations.

IKIP downregulates THBS1/FAK signaling to suppress migration and invasion by glioblastoma cells

Background:Inhibitor of NF-κB kinase-interacting protein(IKIP)is known to promote proliferation of glioblastoma(GBM)cells,but how it affects migration and invasion by those cells is unclear.Methods:We compared levels of IKIP between glioma tissues and normal brain tissue in clinical samples and public databases.We examined the effects of IKIP overexpression and knockdown on the migration and invasion of GBM using transwell and wound healing assays,and we compared the transcriptomes under these different conditions to identify the molecular mechanisms involved.Results:Based on data from our clinical samples and from public databases,IKIP was overexpressed in GBM tumors,and its expression level correlated inversely with survival.IKIP overexpression in GBM cells inhibited migration and invasion in transwell and wound healing assays,whereas IKIP knockdown exerted the opposite effects.IKIP overexpression in GBM cells that were injected into mouse brain promoted tumor growth but inhibited tumor invasion of surrounding tissue.The effects of IKIP were associated with downregulation of THBS1 mRNA and concomitant inhibition of THBS1/FAK signaling.Conclusions:IKIP inhibits THBS1/FAK signaling to suppress migration and invasion of GBM cells.

Charge self-consistent dynamical mean field theory calculations incombination with linear combination of numerical atomic orbitalsframework based density functional theory

We present a formalism of charge self-consistent dynamical mean field theory(DMFT)in combination with densityfunctional theory(DFT)within the linear combination of numerical atomic orbitals(LCNAO)framework.We implementedthe charge self-consistent DFT+DMFT formalism by interfacing a full-potential all-electron DFT code with threehybridization expansion-based continuous-time quantum Monte Carlo impurity solvers.The benchmarks on several 3d,4fand 5f strongly correlated electron systems validated our formalism and implementation.Furthermore,within the LCANOframework,our formalism is general and the code architecture is extensible,so it can work as a bridge merging differentLCNAO DFT packages and impurity solvers to do charge self-consistent DFT+DMFT calculations.

Thermally Evaporated ZnSe for Efficient and Stable Regular/Inverted Perovskite Solar Cells by Enhanced Electron Extraction

Electron transport layers(ETLs)are crucial for achieving efficient and stable planar perovskite solar cells(PSCs).Reports on versatile inorganic ETLs using a simple film fabrication method and applicability for both low-cost planar regular and inverted PSCs with excellent efficiencies(>22%)and high stability are very limited.Herein,we employ a novel inorganic ZnSe as ETL for both regular and inverted PSCs to improve the efficiency and stability using a simple thermal evaporation method.The TiO_(2)-ZnSe-FAPbl_(3)heterojunction could be formed,resulting in an improved charge collection and a decreased carrier recombination further proved through theoretical calculations.The optimized regular PSCs based on TiO_(2)/ZnSe have achieved 23.25%efficiency with negligible hysteresis.In addition,the ZnSe ETL can also effectively replace the unstable bathocuproine(BCP)in inverted PSCs.Consequently,the ZnSe-based inverted device realizes a champion efficiency of 22.54%.Moreover,the regular device comprising the TiO_(2)/ZnSe layers retains 92%of its initial PCE after 10:00 h under 1 Sun continuous illumination and the inverted device comprising the C_(60)/ZnSe layers maintains over 85%of its initial PCE at 85℃for 10:00 h.This highlights one of the best results among universal ETLs in both regular and inverted perovskite photovoltaics.

胸腔镜肺癌根治术后早期并发高危肺栓塞介入溶栓治疗经验

背景与目的肺栓塞(pulmonary thrombosis embolism, PTE)是肺癌根治术围术期严重并发症之一,其中高危PTE因伴有休克、低血压具有病情进展快、死亡率高的特点。这类患者的治疗目前尚无统一标准,是胸外科医生临床工作中的难点。本文通过总结分析我院2例肺癌术后早期并发高危PTE患者的治疗过程,探讨此类病例的诊疗策略,为广大胸外科医生提供参考。方法分析2017年在我院接受胸腔镜肺癌根治手术术后早期并发高危PTE患者两例。1例予静脉联合肺动脉介入溶栓治疗,1例予单纯肺动脉介入溶栓治疗。总结分析两例病人治疗效果及治疗过程中出现的并发症。结果 2例患者均为女性,年龄分别为66岁、61岁,发生PTE的时间分别为术后48 h、45h,接受介入溶栓时间分别是发病后70 min、50 min,介入治疗时间分别是120 min、100 min,介入溶栓后引流分别是4,690 mL、520 mL,溶栓后住院时间分别是21 d、14 d,随访6个月均无明显并发症。结论肺癌术后早期发生高危PTE建议尽早行肺动脉内介入溶栓治疗,相对于静脉溶栓治疗,肺动脉内介入溶栓具有给药精准、药物用量容易控制、疗效快、出血风险小等优点。

法医遗传学研究和鉴定中的伦理问题

法医遗传学主要以人体生物检材为对象,通过检测遗传信息解决与法律相关的生物检材鉴识问题,为侦查提供线索,为审判提供证据,往往涉及到众多伦理问题。本文提出伦理学在法医遗传学研究和鉴定中的应用基本原则,并对检材/样本收集、法医DNA表型分析、法医遗传系谱学分析、法医DNA数据库建设和应用、亲子鉴定和亲缘鉴定、法医遗传学科研数据交流和共享等方面涉及的伦理问题进行了分析,提示法医遗传学从业人员在研究和鉴定中要充分考虑伦理问题,建议有关部门制定法医遗传学具体的伦理要求,建立伦理审查制度,加强从业人员伦理学培训。

基于有限突变模型和大规模数据的19个常染色体STR的实际突变率研究

短串联重复序列(short tandem repeat,STR)已广泛用于法医学亲子鉴定和个体识别中,但STR的突变可能会影响其结果的解释。在大多数类似研究中,由于忽略“隐性”突变现象,STR的突变率被低估。鉴于此,为获得更加准确的STR实际突变率,本研究使用Slooten与Ricciardi提出的有限突变模型和大规模数据,对28,313例(78,739个体)中国北京汉族已确认亲生关系的亲子鉴定案的20个常染色体STR基因座(D3S1358、D1S1656、D13S317、Penta E、D16S539、D18S51、D2S1338、CSF1PO、Penta D、TH01、vWA、D21S11、D6S1043、D7S820、D5S818、TPOX、D8S1179、D12S391、D19S433和FGA;由于有限突变模型中未包含D6S1043的矫正参数,因此本文实际计算其余19个STR基因座的突变率)进行了调查。结果发现,所有基因座均存在突变现象,总计发生1665个突变事件,包括1614个一步突变,34个两步突变,8个三步突变和9个非整步突变。基因座特异性的平均实际突变率在三联体中为0.00007700(TPOX)~0.00459050(FGA),在二联体中为0.00000000(TPOX)~0.00344850(FGA)。此外,本研究还分析了表面和实际突变率、三联体和二联体突变率、父源和母源的突变率之间的关系。研究表明,实际突变率多大于表面突变率,而且μ1^(*)/μ2^(*)(表面突变率)的比值通常也大于μ1/μ2(实际突变率)(μ1^(*),μ1;μ2^(*),μ2分别是一步和两步的突变率),即更多的“隐性”突变被释放出来。而且父源和母源的三联体和二联体的突变率也有存在差异。随后,将这些突变率数据与已发表的中国其他汉族人口的相关研究进行比较,展现出了STR突变率的时间与区域差异。由于样本量大,本研究中还报告了一些少见的突变事件,例如同卵双胞胎突变和“假四步突变”等。综上所述,本研究通过大量数据获得了接近真实的STR突变率的估计值,不仅可为中国法医DNA数据库和群体遗传学数据库提供重要的基础数据,也对开展法医学个体识别、亲权鉴定和遗传学研究具有重要的意义。

Wheat powdery mildew resistance gene Pm64 derived from wild emmer (Triticum turgidum var.dicoccoides) is tightly linked in repulsion with stripe rust resistance gene Yr5

Stripe rust and powdery mildew are both devastating diseases for durum and common wheat.Pyramiding of genes conferring resistance to one or more diseases in a single cultivar is an important breeding approach to provide broader spectra of resistances in wheat improvement. A new powdery mildew resistance gene originating from wild emmer(Triticum turgidum var.dicoccoides) backcrossed into common wheat(T. aestivum) line WE35 was identified. It conferred an intermediate level of resistance to Blumeria graminis f. sp. tritici isolate E09 at the seedling stage and a high level of resistance at the adult plant stage. Genetic analysis showed that the powdery mildew resistance in WE35 was controlled by a dominant gene designated Pm64. Bulked segregant analysis(BSA) and molecular mapping indicated that Pm64 was located in chromosome bin 2 BL4-0.50–0.89. Polymorphic markers were developed from the corresponding genomic regions of Chinese Spring wheat and wild emmer accession Zavitan to delimit Pm64 to a 0.55 cM genetic interval between markers WGGBH1364 and WGGBH612, corresponding to a 15 Mb genomic region on Chinese Spring and Zavitan 2 BL, respectively. The genetic linkage map of Pm64 is critical for fine mapping and cloning. Pm64 was completely linked in repulsion with stripe rust resistance gene Yr5. Analysis of a larger segregating population might identify a recombinant line with both genes as a valuable resource in breeding for resistance to powdery mildew and stripe rust.

Relationship between electrochemical characteristics and SCC of X70 pipeline steel in an acidic soil simulated solution

Stress corrosion cracking （SCC） of X70 pipeline steel in simulated solution of the acidic soil in Yingtan in China was investigated using slow strain rate test （SSRT）, SEM and potentiodynamic polarization technique. Experiment results indicate that X70 steel is highly susceptible to SCC as applied potential reduces, which is manifested in loss of toughness and brittle fracture. Constaat polarization current can detect the occurrence of SCC. The lower the polarization current is the sooner stress corrosion cracking occurs. The SCC mechanisms are different at varying potentials. When potential is higher than open circuit potential, anodic process controls SCC, whereas when potential is far lower than open circuit potential, cathodic process controls SCC, and between these two potential regions, a combined electrochemical process controls the SCC. Stress or strain has a synergistic effect with electrochemical reactions to accelerate the cathodic hydrogen evolution process, which makes the X70 pipeline steel to be more susceptible to SCC.

Mapping stripe rust resistance genes by BSR-Seq:YrMM58 and YrHY1 on chromosome 2AS in Chinese wheat lines Mengmai 58 and Huaiyang 1 are Yr17

Stripe rust(yellow rust), caused by Puccinia striiformis f. sp. tritici(PST),is one of the most devastating fungal diseases in common wheat(Triticum aestivum L.) in China and worldwide. Resistance breeding is the most effective strategy to control diseases in crop plants. Chinese wheat lines Mengmai 58 and Huaiyang 1 are highly resistant to PST race CYR34(V26) at the adult plant stage. To genetically map the underlying resistance genes we developed segregating populations by crossing Mengmai 58 and Huaiyang 1 with the susceptible cultivar Nongda 399. The stripe rust resistances in Mengmai 58 and Huaiyang 1 were both controlled by single dominant genes, provisionally designated YrMM58 and YrHY1, respectively. Bulked segregant RNA-Seq(BSR-Seq) analysis showed that YrMM58 and YrHY1 were located in the same distal ~16 Mb region on chromosome 2 AS.Comparative genomics analysis with the physical map of Aegilops tauschii proved useful for developing additional markers to saturate the genetic linkage map. YrMM58 and YrHY1 were mapped to the distal end of chromosome arm 2 AS, with the closest marker WGGB148 being 7.7 cM and 3.8 cM from the resistance gene, which was considered to be Yr17. These markers can be used in marker-assisted selection.

Efficient Carbon-Based CsPbBr_3 Inorganic Perovskite Solar Cells by Using Cu-Phthalocyanine as Hole Transport Material

Metal halide perovskite solar cells(PSCs) have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency(PCE)and low fabrication cost. Although the world's best PSC successfully achieves a considerable PCE of over 20% within a very limited timeframe after intensive efforts, the stability, high cost, and up-scaling of PSCs still remain issues. Recently, inorganic perovskite material, CsPbBr_3, is emerging as a promising photo-sensitizer with excellent durability and thermal stability, but the efficiency is still embarrassing. In this work, we intend to address these issues by exploiting CsPbBr_3 as light absorber, accompanied by using Cu-phthalocyanine(CuPc) as hole transport material(HTM) and carbon as counter electrode. The optimal device acquires a decent PCE of 6.21%, over 60% higher than those of the HTM-free devices. The systematic characterization and analysis reveal a more effective charge transfer process and a suppressed charge recombination in PSCs after introducing CuPc as hole transfer layer. More importantly, our devices exhibit an outstanding durability and a promising thermal stability, making it rather meaningful in future fabrication and application of PSCs.

A MITE insertion into the 3′-UTR regulates the transcription of TaHSP16.9 in common wheat

Miniature inverted-repeat transposable elements(MITEs) are a type of DNA transposon frequently inserted into promoters, untranslated regions(UTR), introns, or coding sequences of genes. We found a 276-bp tourist-like MITE insertion in the 3′-UTR of a 16.9 k Da small heat shock protein gene(TaH SP16.9-3A) on chromosome 3A of common wheat. Haplotype analysis revealed two haplotypes, s HSP-W(wild type without MITE insertion) and s HSP-M(mutant with MITE insertion), present in wheat germplasm. Both semiquantitative PCR and quantitative real-time PCR analyses showed increased transcription levels of TaH SP16.9-3A in s HSP-M compared with those of s HSP-W after heat treatment at 42 °C. It appeared that the MITE insertion into the 3′-UTR enhances the transcription of TaH SP16.9-3A.

Dissecting conserved cis-regulatory modules of Glu-1 promoters which confer the highly active endosperm-specific expression via stable wheat transformation

Wheat high-molecular-weight glutenin subunits(HMW-GS) determine dough elasticity and play an essential role in processing quality. HMW-GS are encoded by Glu-1 genes and controlled primarily at transcriptional level, implemented through the interactions between cis-acting elements and trans-acting factors. However, transcriptional mechanism of Glu-1 genes remains elusive. Here we made a comprehensive analysis of cis-regulatory elements within 1-kb upstream of the Glu-1 start codon(-1000 to-1) and identified 30 conserved motifs. Based on motif distribution pattern, three conserved cis-regulatory modules(CCRMs), CCRM1(-300 to-101), CCRM2(-650 to-400), and CCRM3(-950 to-750), were defined, and their functions were characterized in wheat stable transgenic lines transformed with progressive 5′ deletion promoter::GUS fusion constructs. GUS staining, qP CR and enzyme activity assays indicated that CCRM2 and CCRM3 could enhance the expression level of Glu-1, whereas the 300-bp promoter(-300 to-1), spanning CCRM1 and core region(-100 to-1), was enough to ensure accurate Glu-1 initiation at 7 days after flowering(DAF) and shape its spatiotemporal expression pattern during seed development. Further transgenic assays demonstrated that CCRM1-2(-300 to-209) containing Complete HMW Enhancer(-246 to-209) was important for expression level but had no effect on expression specificity in the endosperm. In contrast, CCRM1-1(-208 to-101) was critical for both expression specificity and level of Glu-1. Our findings not only provide new insights to uncover Glu-1 transcription regulatory machinery but also lay foundations for modifying Glu-1 expression.

Mapping a leaf senescence gene els1 by BSR-Seq in common wheat

Leaf senescence is normally the last stage of plant development. Early senescence of functional leaves significantly reduces the photosynthetic time and efficiency, seriously affecting grain yield and quality in wheat. Discovering genes responsible for early leaf senescence(els) are necessary for developing novel germplasms and cultivars with delayed leaf-senescence through molecular manipulation and marker assisted selection. In this study, we identified an early leaf senescence line M114 in a derivative of a wheat breeding population. Genetic analysis indicated that early leaf senescence in M114 is controlled by a single recessive gene, provisionally designated els1. By applying bulked segregant analysis and RNA-Seq(BSR-Seq), seven polymorphic markers linked to els1 were developed and the gene was located on chromosome arm 2 BS in a 1.5 c M genetic interval between markers WGGB303 and WGGB305. A co-segregating marker, WGGB302, provide a starting point for fine mapping and map-based cloning of els1.

Effect of cathodic potential on stress corrosion cracking behavior of 21Cr2NiMo steel in simulated seawater

This study aims at providing systematically insights to clarify the impact of cathodic polarization on the stress corrosion cracking(SCC)behavior of 21 Cr2 NiMo steel.Slow-strain-rate tensile tests demonstrated that 21 Cr2 NiMo steel is highly sensitive to hydrogen embrittlement at strong cathodic polarization.The lowest SCC susceptibility occurred at-775 mV vs.SCE,whereas the SCC susceptibility was remarkably higher at potentials below-950 mV vs.SCE.Scanning electron microscopy(SEM)and electron backscattered diffraction(EBSD)revealed that the cathodic potential decline caused a transition from transgranular to intergranular mode in the fracture path.The intergranular mode transformed from bainite boundaries separation to prior austenitic grain boundaries separation under stronger cathodic polarization.Furthermore,corrosion pits promoted the nucleation of SCC cracks.In conclusion,with the decrease in the applied potential,the SCC mechanism transformed from the combination of hydrogen embrittlement and anodic dissolution to typical hydrogen embrittlement.

Au-Ag alloy nanoparticles with tunable cavity for plasmon-enhanced photocatalytic H2 evolution

Au-Ag alloy nanoparticles with different cavity sizes have great potential for improving photocatalytic performance due to their tunable plasmon effect.In this study,galvanic replacement was combined with co-reduction with the reaction kinetics processes regulated to rapidly synthesize Au-Ag hollow alloy nanoparticles with tunable cavity sizes.The position of the localized surface plasmon resonance(LSPR)peak could be effectively adjusted between 490 nm and 713 nm by decreasing the cavity size of the Au-Ag hollow nanoparticles from 35 nm to 20 nm.The plasmon-enhanced photocatalytic H2 evolution of alloy nanoparticles with different cavity sizes was investigated.Compared with pure P25(TiO2),intact and thin-shelled Au-Ag hollow nanoparticles(HNPs)-supported photocatalyst exhibited an increase in the photocatalytic H2 evolution rate from 0.48μmol h^−1 to 4μmol h^−1 under full-spectrum irradiation.This improved photocatalytic performance was likely due to the plasmon-induced electromagnetic field effect,which caused strong photogenerated charge separation,rather than the generation of hot electrons.

Defect in Brnym1,a magnesium-dechelatase protein,causes a stay-green phenotype in an EMSmutagenized Chinese cabbage(Brassica campestris L.ssp.pekinensis)line

Leaf color is an important target trait in Chinese cabbage breeding programs.Leaf yellowing may reduce crop commercial and nutritional values.Some plants with the“stay-green”trait maintain leaf greenness during senescence and even after death.Stay-green Chinese cabbage may be a focal point of future breeding projects because it could improve crop quality and yield and prolong shelf life.A new stay-green mutant,non-yellowing mutant 1(nym1),was identified in Chinese cabbage derived from an ethyl methane sulfonate(EMS)-mutagenized population.The mutant had stay-green characteristics and a higher chlorophyll content than the wild-type during leaf senescence.The staygreen trait in the mutant Chinese cabbage was controlled by the recessive gene Brnym1.MutMap and KASP analyses showed that Brnym1(BraA03g050600.3C)encodes an mg-dechelatase(SGR protein),which might be the causal gene of the mutation in Chinese cabbage.A nonsynonymous single nucleotide base substitution(G to A)in the third exon of Brnym1 caused an amino acid substitution from L to F in the highly conserved domain of the magnesiumdechelatase.Ectopic overexpression showed that the BrNYM1 gene of wild-type Chinese cabbage complemented the SGR-defective stay-green mutant nye1-1 of Arabidopsis.The magnesium-dechelatase activity in the nym1 mutant was significantly downregulated compared to that in the wild type.Brnym1 was relatively upregulated in the mutant during late senescence,and BrNYM1 was localized to the chloroplasts.These results indicate that Brnym1(BraA03g050600.3C)is the causal gene of the stay-green mutation and could be of particular significance in the genetic improvement of Chinese cabbage.