A novel high-Cr CoNi-based superalloy with superior high-temperature microstructural stability, oxidation resistance and mechanical properties

A novel multicomponent high-Cr CoNi-based superalloy with superior comprehensive performance was prepared,and the evaluation of its high-temperature microstructural stability,oxidation resistance,and mechanical properties was conducted mainly using its cast polycrystalline alloy.The results disclosed that the morphology of theγ′phase remained stable,and the coarsening rate was slow during the long-term aging at 900–1000℃.The activation energy forγ′precipitate coarsening of alloy 9CoNi-Cr was(402±51)kJ/mol,which is higher compared with those of CMSX-4 and some other Ni-based and Co-based superalloys.Importantly,there was no indica-tion of the formation of topologically close-packed phases during this process.All these factors demonstrated the superior microstructural stability of the alloy.The mass gain of alloy 9CoNi-Cr was 0.6 mg/cm^(2) after oxidation at 1000℃ for 100 h,and the oxidation resistance was comparable to advanced Ni-based superalloys CMSX-4,which can be attributed to the formation of a continuous Al_(2)O_(3) protective layer.Moreover,the compressive yield strength of this cast polycrystalline alloy at high temperatures is clearly higher than that of the conventional Ni-based cast superalloy and the compressive minimum creep rate at 950℃ is comparable to that of the conventional Ni-based cast superalloy,demonstrating the alloy’s good mechanical properties at high temperature.This is partially because high Cr is bene-ficial in improving theγandγ′phase strengths of alloy 9CoNi-Cr.

A Light and Simplified Branch Bending Method for Young Pear Trees

Aiming at high cost and low efficiency of conventional branch bending method in the modern intensive planting and labor-saving cultivation mode of young pear trees,this paper provides a new branch bending method with wide source of raw materials,cheap price and simple operation,which is also suitable for the management of low-age branches in the process of high grafting and upgrading of traditional big trees.

Optimization of Texture Determination of ‘Yali' by Texture Analyzer

[Objectives] This study was carried out to determine texture parameters for texture profile analysis （TPA）, and optimize the texture determination of ‘Yali’ by texture analyzer.[Methods] The traditional varieties of ‘Yali’ were taken as the materials, and texture parameters were determined at different compression rates and deformations at target.[Results] In the process of the TPA, the deformation at target had an extremely significant influence on 8 TPA texture parameters, namely, the hardness, cohesiveness, springiness, adhesiveness, gumminess, resilience, fracturability, and chewiness （ P ≤0.01）, while the compression rate had significant influence on the hardness and gumminess （ P ≤0.05）, had an extremely significant influence on fracturability （ P ≤0.01）, and had no significant influence on other 5 TPA parameters.[Conclusions] Taking the compression rate of 1 mm/s and 20% deformation at target as the experimental conditions for TPA could avoid the impact load of high speed on the tissue and objectively reflect the textural characteristics of ‘Yali’ pulp tissue.

Aeroelastic dynamics stability of rotating sandwich annular plate with viscoelastic core layer

A dynamic model for a rotating sandwich annular plate with a viscoelastic core layer is developed. All fundamental equations and boundary conditions are estab- lished based on Hamilton＇s principle, and the rotation effect and viscoelastic properties of the sandwich structure are taken into account. The aerodynaxnics force acting on the plate is described by a rotating damping model, and the constitutive behavior of the viscoelastic core layer is formulated by the frequency-dependent complex modulus. The effects of geometrical and material parameters on frequencies and damping of forward and backward traveling waves and the dynamic stability for the rotating sandwich plate axe numerically analyzed by means of Galerkin＇s method. The results show that the critical and flutter speeds of the rotating plate can he increased at some certain parameters of the viscoelastic core layer.

Geometric Calibration and Image Quality Assessment of High Resolution Dual-Camera Satellite

The evaluation of geometric calibration accuracy of high resolution satellite images has been increasingly recognized in recent years.In order to evaluate geometric accuracy for dual-camera satellite images based on the ground control points(GCP),a rigorous geometric imaging model,which was based on the collinear equation of the probe directional angle and the optimized tri-axial attitude determination(TRIAD)algorithm,is presented.Two reliable test fields in Tianjin and Jinan(China)were utilized for geometric accuracy validation of Pakistan Remote Sensing Satellite-1.The experimental results demonstrate a certain deviation of the on-orbit calibration result from the initial design values of the calibration parameters.Therefore,on-orbit geometric calibration is necessary for optical satellite imagery.Within this research,the geometrical performances including positioning accuracy without/with GCP and band registration of the dual-camera satellite were analyzed in detail,and the results of geometric image quality are assessed and discussed.As a result,it is feasible and necessary to establish such a geometric calibration model to evaluate the geometric quality of dual-camera satellite.

A Training System of Pear Trees for Simplified High-density Cultivation

In view of the deficiencies of training technologies during constructing pear orchards by modern simplified dense-planting cultivation with ordinary pear seedlings widely used in production,a simple and easy-to-operate training method was proposed,mainly including constructing fence nets,determining low main trunks,leaving buds at the northwest position,multiple bud removal,winding and notching,simplified branch supporting,and simplified branch pulling.

Enhanced anomalous Hall effect in kagome magnet YbMn_(6)Sn_(6)with intermediate-valence ytterbium

We report on the magnetization and anomalous Hall effect(AHE)in the high-quality single crystals of the kagome magnet YbMn_(6)Sn_(6),where the spins of the Mn atoms in the kagome lattice order ferromagnetically and the intermediate-valence Yb atoms are nonmagnetic.The intrinsic mechanism plays a crucial role in the AHE,leading to an enhanced anomalous Hall conductivity(AHC)compared with the other rare-earth RMn_(6)Sn_(6)compounds.Our band structure calculation reveals a strong hybridization between the 4f electrons of Yb and conduction electrons.

Evaluation of Cold Resistance and Semi-lethal Low Temperature(LT_(50))of Nine Pear Cultivars

[Objectives]To evaluate the cold resistance and semi-lethal temperature of pear cultivars,and provide a theoretical basis for the regional extension and breeding of cold-resistant pear cultivars.[Methods]Nine pear cultivars were used to study the changes in relative conductivity and cell injury rate of pear branches under low temperature stress,and the semi-lethal temperature(LT_(50))of pear branches was analyzed by fitting Logistic equation.[Results]The relative conductivity and cell injury rate of pear branches took on the trend of slow increase,rapid increase,and slow increase the decrease of treatment temperature.The LC_(50) of the nine pear cultivars were as follows:Nanguo pear-33.9℃,Wanyu-32.3℃,Red D Anjou-31.8℃,Jinfeng-31.3℃,Wujiuxiang-29.2℃,20 th Century Pear-29.1℃,Hanxiang-35.1℃,Yuluxiang-27.9℃ and Korla Fragrant Pear-29.2℃.[Conclusions]The semi-lethal temperature could reflect the cold resistance of pear trees,and Wanxiang had better cold resistance.The evaluation of cold resistance and semi-lethal temperature of pear cultivars can provide theoretical basis for regional extension and breeding of cold-resistant pear cultivars.

Advances in Molecular Regulatory Mechanisms of Fruit Trees under Low Temperature Stress

The most recent research findings on the tolerance of fruit trees to cold stress are reviewed from a molecular perspective,including the perception and transduction of low temperature calcium signaling,CBF-dependent molecular regulatory mechanisms,non-CBF-dependent molecular regulatory mechanisms,and so forth.The objective is to provide a reference basis for further improving the cold resistance of fruit trees and cultivating new varieties of hardy plants.

A method for Improving the Efficiency of Pear Tree Crossbreeding

In view of the short blooming period of pear tree crossbreeding and the complexity of pollination process, a method that can improve the efficiency of crossbreeding of pear trees was provided. Meanwhile, this method can also be applied to the study of pollen xenia effect, pollination tree selection and pure pollen collection in pear tree cultivation.

Robust Position Anti-Interference Control for PMSM Servo System With Uncertain Disturbance

Aiming to suppress the influence of uncertain disturbances in the drive control of permanent magnet synchronous machines(PMSM),such as the parameter uncertainties and load disturbance,a robust anti-interference control for the angular position tracking control of a PMSM servo system has been proposed in this paper.During the position tracking,uncertain system disturbances being regarded as a lumped unknown term will be online observed by a nonlinear disturbance observer(NDOB),of which the influence will consequently be counteracted by a robust backstepping compensator(RBC).The asymptotical stability of proposed control scheme is analyzed and designed according to the Lyapunov stability criterion,and its convergence against the system uncertain disturbance is verified on a prototype PMSM servo platform and shows good performance in rotor angular position tracking and anti-interference.

Ecological damage of submerged macrophyte Myriophyllum spicatum by cell extracts from microcystin(MC)-and non-MC-producing cyanobacteria,Microcystis

To explore how decomposed Microcystis-dominant cyanobacterial blooms affect submerged macrophytes,the submerged plant Myriophyllum spicatum was exposed to cell extracts from microcystin(MC)-and non-MC-producing Microcystis strains in a laboratory experiment.Results showed that both Mcracystis cell extracts exerted obvious damages to plant biomass,photosynthesis,primary and secondary metabolism measures,and resistance of plant antioxidant systems,with MC-producing Microcystis having stronger effects due to the presence of MCs.Cyanotoxins other than MCs responsible for the negative effects from both strains needs further identification.The Shannon diversity and Chao1 indices of epiphytic and planktonic bacteria were decreased by the cell extracts from both Microcystis strains.However,epiphytic and planktonic bacterial communities responded differently to cell extracts at the genus level.The dominant genera of planktonic bacteria including Enterobacter,Pseudomonas,and Novosphingobium from phylum Proteobacteria,Chryseobacterium from phylum Bacteroidetes,and Microbacterium from Actinobacteriota in the treatments with cell extracts were previously reported to have strains with algicidal and MC-degrading capabilities.B acterial genes associated with energy production and conversion,amino acid transport and metabolism,and inorganic ion transport and metabolism,were more abundant in both treatments than the control for planktonic bacteria,but less abundant for epiphytic bacteria.We speculate that planktonic bacterial communities have the potential to use and degrade substances derived from Microcystis cell extracts,which may be beneficial for M.spicatum to alleviate damages from Microcystis.Further research is needed to verify the structure and function dynamics of epiphytic and planktonic bacteria in the interaction between cyanobacteria and submerged macrophytes.

Isothermal oxidation behavior of Nb-bearing austenitic cast steels at 950℃

The oxidation behaviors of three austenitic cast steels with different morphologies of primary carbides at 950℃ in air were investigated using scanning electron microscopy,energy dispersive spectroscopy,and focused ion beam/transmission electron microscopy.Their oxidation kinetics followed a logarithmic law,and the oxidation rate can be significantly decreased as long as a continuous silica layer formed at the scale/substrate interface.When the local Si concentration was inadequate,internal oxidation occurred beneath the oxide scale.The spallation of oxides during cooling can be inhibited with the formation of internal oxidation,owing to the reduced mismatch stress between the oxide scale and the substrate.The“Chinese-script”primary Nb(C,N)was superior to the dispersed primary Nb(C,N)in suppressing the oxidation penetration in the interdendritic region by supplying a high density of quick-diffusion Cr channels.In addition,the innermost and outermost oxidation layers were enriched with Cr,whereas the Cr evaporation in the outermost layer was significant when the water vapor concentration in the environment was high enough.These findings further the understanding regarding the oxidation behavior of austenitic cast steels and will promote the alloy development for exhaust components.

Study on the Changes of the Major Nutrient Elements During Simple Composting Process of Dry Chicken Manure

[Objectives]This study was conducted to provide a theoretical basis for production and application of chicken manure compost.[Methods]With dry manure as a material,the variations of the major nutrients during simple composting process of dry chicken manure were studied,in order to get the best fermentation method.[Results]Chicken manure should not be preserved wet,but should be preserved after air-drying and fermented before use.Necessary moisture,simple sealing treatment and a certain amount of N element were conducive to simple fermentation of chicken manure.The treatments in which the chicken manure was wrapped around and compacted,added with an appropriate amount of water(50%-60%)and naturally fermented,or was wrapped around and compacted and added with an appropriate amount of water(50%-60%)and 0.2%of urea,were more appropriate for the production directly.[Conclusions]This study provides a theoretical basis for the actual production and application of chicken manure compost.

Construction of Technology System on Development and Repropagation in Vitro of Several Cultivars in Pear

It is the most available way to obtain self-rooted seedlings by tissue culture,which could breed de-virus seedlings with uniform traits and contribute to improve seedling quality.To construct a complete and efficient technology system,this test used stem with buds of 16 cultivars and super lines including Yali,Jingbaili,03-04-034,03-08-080 and so on as materials to study the best way for explant sampling time and position,sterilization time using HgCl 2 and hormone concentrations.The result indicated that the optimum technology system was that the middle parts of longest shoots before 20 d after full-blossom were sterilized for 8 min by 0.1%HgCl 2 and inoculated on the development medium MS+6-BA 0.5 mg/L+IBA 0.2 mg/L+saccharose 3%+agar 0.6%(pH=5.8),and then trans-inoculated into propagation medium MS+6-BA 1.0 mg/L+IBA 0.3 mg/L+saccharose 3%+agar 0.6%(pH=5.8).

Differential Gene Expression and Analysis inVenturia nashicola-inoculated and UninoculatedLeaves of the New Highly Resistant Germplasm03-04-034

The super line 03-04-034, which results from a cross between Pyrus bretchneideri cv Jingbaili and P.ussuriensis cv Yali, is highly resistant to pear scab.Specimens were inoculated with Venturia nashicola to generate a database of expressed sequence tags(ESTs) to be used as resources for transcripts induced in inoculated and uninoculated leaves. After performing subtractive suppression hybridization using cDNA of the inoculated and uninoculated leaves harvested 51 h after inoculation, 100 clones from the uninoculated and 100 clones from the inoculated cDNA library were selected and sequenced. BLASTN searches of each cDNA library against GenBank revealed eight unique sequences associated with the defense response, comprising four ESTs from the uninoculated cDNA library(ubiquitin extension protein, subtilisin-like protease, basic helix-loop-helix(bHLH) transcription factor and aspartic endopeptidase) and four ESTs from the inoculated cDNA library(S-adenosylmethionine synthase(SAMS), heat shock factor(HSF) domain class transcription factor, RNA-binding protein and polyphenol oxidase 5 precursor).Quantitative fluorescence real-time polymerase chain analysis revealed that the transcripts for SAMS and subtilisin-like protease were highly expressed in the incompatible interaction. The SAMS gene was more highly expressed in inoculated leaves than uninoculated leaves, while the reverse was true for subtilisin-like protease. The SAMS and subtilisin-like protease genes have been found to be associated with plant defense mechanisms. Further studies of greater detail are required to understand how these genes are expressed and regulated during infection with V.nashicola.

Occurrence and Integrated Control of Psylla chinensis in Eastern Hebei Province

The paper introduces the damage characteristics and occurrence regularity of Psylla chinensis in pear orchards in eastern Hebei Province,and summarizes the integrated prevention and control techniques of P.chinensis,in order to provide a reference for the prevention and control of P.chinensis in eastern Hebei Province.

Occurrence and Control of Pear Rust in Eastern Hebei Province

In recent years, pear rust sometimes occurs in eastern Hebei area, resulting in early defoliation, fruit abscission and loss of fruit commodity value. In this paper, the incidence symptoms, regularity and causes of pear rust are summarized, and the comprehensive prevention and control measures of pear rust in eastern Hebei are put forward.

The number and cytotoxicity and the expression of cytotoxicity-related molecules in peripheral natural killer(NK)cells do not predict the repeated implantation failure(RIF)for the in vitro fertilization patients

Natural killer(NK)cells are thought to play a key role in the successful establishment of a pregnancy by facilitating immunological adaptation of the semi-allogeneic developing embryo.The aim of this study was to explore the cell number,immunophenotypic characteristics,and activities of peripheral blood NK cells in women with repeated implantation failure(RIF).Peripheral blood was obtained from 27 women with RIF and 11 healthy,fertile controls during the middle luteal phase of the menstrual cycle.CD3^-CD56^+NK cells were quantified and analyzed by flow cytometry for the expression of cytolytic molecules(granzyme B,granulysin,and perforin)as well as cell surface receptors responsible for NK cell activation or inhibition(NKG2D,NKp30,NKp46,CD158a,CD158b).NK cytotoxicity was measured at three effector-to-target cell ratios.Women with RIF and fertile controls did not differ significantly in the percentage of circulating CD3CD56t NK cells,or in the proportions of these cells that expressed granzyme B,granulysin,or perforin.The two groups also did not differ significantly in the proportions of NK cells expressing the receptors NKG2D,NKp30,NKp46,CD158a or CD158b.General linear model analysis showed that NK cytotoxicity increased with effector-to-target cell ratio.However,NK cytotoxicity did not differ significantly between patients with RIF and fertile controls.These results suggest that RIF is not associated with significant alterations in the number or function of peripheral blood NK cells.

Effects of Ni, Cr and W on the microstructural stability of multicomponent CoNi-base superalloys studied using CALPHAD and diffusion-multiple approaches

The alloying effects of Ni,W and Cron the microstructural stability of CoNi-base alloys were investigated using a multicomponent diffusion multiple after being aged at 1000℃ for 1000 h.The diffusion multiple was carefully designed based on thermodynamic calculations.The relationships between alloy compositions and microstructural characteristics were established over a large compositional range using this single sample,and the alloying effects of Ni,W and Cron the elemental partitioning behaviors betweenγ and γ' two phases were thermodynamically analyzed using high-throughput calculation.The results together show that an increase of Ni content increases the γ' volume faction in the long-term aged microstructures.However,the higher Ni content leads to the precipitation of the χ phase by promoting the partitioning of W from the γ' phase to the γ phase.The decrease of W content dramatically reduces theγ' volume faction,but the addition of Cr can properly counteract this effect by promoting the partitioning of Al and Ti from the γ phase to the γ' phase.This study will be helpful for accelerating the development of novel γ'-strengthened multicomponent CoNi-base alloys,as well as providing experimental data to improve the thermodynamic database.