In eukaryotic organisms,the most common internal modification of messenger RNA(m RNA)is N6-methyladenosine(m6A).This modification can be dynamically and reversibly controlled by specific enzymes known as m6A writers a...In eukaryotic organisms,the most common internal modification of messenger RNA(m RNA)is N6-methyladenosine(m6A).This modification can be dynamically and reversibly controlled by specific enzymes known as m6A writers and erasers.The fat-mass and obesity-associated protein(FTO)catalyzes RNA demethylation and plays a critical role in various physiological and pathological processes.Our research identified dynamic alterations in both m6A and FTO during the assembly of primordial follicles,with an inverse relationship observed for m6A levels and nuclear-localized FTO expression.Application of Fto small interfering RNA(si RNA)altered the expression of genes related to cell proliferation,hormone regulation,and cell chemotaxis,and affected RNA alternative splicing.Overexpression of the full-length Fto gene led to changes in m6A levels,alternative splicing of Cdk5,cell proliferation,cell cycle progression,and proportion of primordial follicles.Conversely,overexpression of Fto lacking a nuclear localization signal(NLS)did not significantly alter m6A levels or primordial follicle assembly.These findings suggest that FTO,localized in the nucleus but not in the cytoplasm,regulates RNA m6A demethylation and plays a role in cell proliferation,cell cycle progression,and primordial follicle assembly.These results highlight the potential of m6A and its eraser FTO as possible biomarkers and therapeutic targets.展开更多
Cracks have consistently been a significant challenge limiting the development of additive manufactured nickel-based superalloys.It is essential to investigate the location of cracks and their forming mechanism.This s...Cracks have consistently been a significant challenge limiting the development of additive manufactured nickel-based superalloys.It is essential to investigate the location of cracks and their forming mechanism.This study extensively examines the impact of solidification process,microstructural evolution,and stress concentration on crack initiation during direct energy deposition(DED).The results emphasize that the crack formation is significantly related to large-angle grain boundaries,rapid cooling rates.Cracks caused by large-angle grain boundaries and a fast-cooling rate predominantly appear near the edge of the deposited samples.Liquation cracks are more likely to form near the top of the deposited sample,due to the presence ofγ/γ'eutectics.The secondary dendritic arm and the carbides in the interdendritic regions can obstruct liquid flow during the final stage of solidification,which results in the formation of solidification cracks and voids.This work paves the way to avoid cracks in nickel-based superalloys fabricated by DED,thereby enhancing the performance of superalloys.展开更多
AIM： To clarify the expression change of Wnt-induced secreted protein-1 （WISP-l） in human rectal cancer and to determine whether it is correlated with invasion and metastasis of human rectal cancer.METHODS： Eighty...AIM： To clarify the expression change of Wnt-induced secreted protein-1 （WISP-l） in human rectal cancer and to determine whether it is correlated with invasion and metastasis of human rectal cancer.METHODS： Eighty-six paired samples of rectal cancer and surgically resected distant normal rectal tissue were collected and allocated into cancer group and control group respectively. WISP-1 mRNA was detected by relative quantitative real-time RT-PCR and WISP-1 protein was examined by immunohistochemical staining.RESULTS： WISP-1 gene overexpression was found in 65% （56/86） primary rectal cancers, 2-30 times that of the level in normal matched rectal tissues （P = 0.001）. The mRNA expression level was correlated with Duke＇s staging, histological differentiation grade and lymph node status. The WISP-1 protein expression was in accordance with mRNA expression level. The positive degree of immunohistochemical staining in the cancer group （1.40±0.35） was different from that in control group （1.04± 0.08, P 〈 0.001）. Moreover, in cancer group the positive staining degree in high-level mRNA cancers （1.46 ±0.37, n = 56） was higher than that in low-level mRNA （1.28 ± 0.28, n = 30, P = 0.018）.CONCLUSION： Aberrant levels of WISP-1 expression may play a role in rectal tumorigenesis. WISP-1 may be used as a specific clinical diagnosis and prognosis marker in rectal cancer.展开更多
The recrystallization behavior of a single crystal nickel-base superalloy was investigated by shot peening and subsequent annealing. Two kinds of recrystallization microstructures, which are intensively dependent on t...The recrystallization behavior of a single crystal nickel-base superalloy was investigated by shot peening and subsequent annealing. Two kinds of recrystallization microstructures, which are intensively dependent on the annealing temperature, are shown in the nickel-base superalloy after shot peening and subsequent annealing. Surface recrystallized grains are obtained when the superalloy is annealed at solution treatment temperature. The nucleation of recrystallization originates from the dendritic core, where rapid dissolution of γ＇ particles occurs. Cellular recrystallization is observed after annealing at lower temperatures. Cellular structures induced by high diffusivity of the moving boundary and more γ＇ particles dissolution led by residual stress are developed from the surface region. Recrystallized kinetics of the shot-peened alloy annealed at 1050°C accords with the Johnson-Mehl-Avrami-Kolmogorov equation. The low Avrami exponent is caused by the inhomogeneous distribution of stored energy, the decreasing of stored energy during recovery, and the strong resistance of boundary migration by γ＇ particles.展开更多
AIM： To study the relationship between particularly interesting new cysteine-histidine rich protein （PINCH） expression and clinicopathological factors in Chinese colorectal cancer patients. METHODS： The expression...AIM： To study the relationship between particularly interesting new cysteine-histidine rich protein （PINCH） expression and clinicopathological factors in Chinese colorectal cancer patients. METHODS： The expression of PINCH was examined by immumohistochemistry in 141 samples of primary colorectal adenocarcinoma and 92 normal samples of colorectal mucosa. Eighty of the cases had both primary tumour and normal mucosa from the same patients. RESULTS： PINCH was expressed in the stroma of normal mucosa and tumours. PINCH expression in tumourassociated stroma was increased compared to normal mucosa in both unmatched cases （n = 141, x^2 = 85.79, df = 3, P〈 0.0001） and matched cases （n =80, x^2= 45.86, df= 3, P〈 0.0001）. Among 135 tumours with visible invasive margin, 86 （64%） showed stronger PINCH expression at the invasive margin than in the intratumoural stroma. The frequency of PINCH strong expression in mucinous and signet-ring cell carcinomas was higher （52%） compared to non-mucinous carcinomas （29%, x^2=5.13, P= 0.02）. We did not find that PINCH expres- sion was related to patient＇s gender, age, tumour location, tumour size, gross status, histological type, differentiation, invasion depth, lymph node status and Dukes＇ stage （P 〉 0.05）.CONCLUSION： The expression of PINCH was upregulated in colorectal cancers, and especially at the margin of tumours, and further was related to mucinous and signet-ring cell carcinomas. The results suggest that expression of PINCH may be involved in the tumourigenesis and aggressiveness of colorectal cancers.展开更多
With ongoing development of oil exploration and techniques,there is a significant need for improved well control strategies and formation pressure prediction methods.In this paper,a gas-liquid transient drift flow mod...With ongoing development of oil exploration and techniques,there is a significant need for improved well control strategies and formation pressure prediction methods.In this paper,a gas-liquid transient drift flow model was established according to the gas-liquid two-phase flow characteristics during the gas kick.A Roe scheme was used for numerical calculation based on the finite volume method.The changes of bottom-hole pressure,casing pressure,the development law of cross-sectional gas holdup,and gas velocity,along with the vertical well depth,were analyzed through simulation examples.The time-series characteristics of mud pit gain were obtained by adjusting the formation parameter.The complex nonlinear mapping relationship between the formation parameters and the mud pit gain was established.The long short-term memory network(LSTM)of deep learning was used to obtain a formation pressure inversion when the blowout is out of control and the well cannot be shut-in.Experimental data from a well were used to verify the gas-liquid two-phase transient drift flow model based on the finite volume method,demonstrating that this method is reliable,with greatly improved prediction accuracy.This approach provides theoretical support for the early monitoring of gas kick during drilling,and for well-killing design and construction after uncontrolled blowout.展开更多
AIM： To examine whether polymorphisms in SULTIA1 and GSTP1 genes contribute to colorectal cancer development and whether they are associated with clinicopathological variables are not well identified. METHODS： We ex...AIM： To examine whether polymorphisms in SULTIA1 and GSTP1 genes contribute to colorectal cancer development and whether they are associated with clinicopathological variables are not well identified. METHODS： We examined the genotypes of 125 colorectal cancer patients and 666 healthy controls in a Swedish population by using PCR-restriction fragment length polymorphism （RFLP）. RESULTS： SULTIA1 ＊2/＊2 genotype （OR = 2.49, 95%CI = 1.48-4.19, P = 0.0002） and ＊2 allele （OR = 1.56, 95%CI =1.16-2.10, P = 0.002） had an effect on colorectal cancer susceptibility, while GSTP1 genotype was without effect. However, GSTP1 G-type predicted a worse prognosis in the patients independently of gender, age, Dukes＇ stage, growth pattern, and differentiation （P = 0.03）.CONCLUSION： Polymorphism in SULTIA1 may predispose to colorectal cancer and GSTP1 may be a biological indicator of prognosis in the patients.展开更多
K416B Ni-based superalloy with high W content has good high temperature properties and low cost,which has a great development potential.To investigate the room temperature tensile property and the deformation feature ...K416B Ni-based superalloy with high W content has good high temperature properties and low cost,which has a great development potential.To investigate the room temperature tensile property and the deformation feature of K416B superalloy,tensile testing at room temperature was carried out,and optical microscopy (OM),scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the deformation and damage mechanisms.Results show that the main room temperature tensile deformation features of the K416B nickel-based superalloy are dislocations slipping in the matrix and shearing into γ’ phase.The <110> super-dislocations shearing into γ’ phase can form the anti-phase boundary two coupled (a/2)<110> partial-dislocations or decompose into the configuration of two (a/3)<112> partial dislocations plus stacking fault.In the later stage of tensile testing,the slip-lines with different orientations are activated in the grain,causing the stress concentration in the regions of block carbide or the porosity,and cracks initiate and propagate along these regions.展开更多
In oil and gas well drilling operations,it is of great significance to accurately predict the drag coefficient and settling velocity of drill cuttings in non-Newtonian drilling fluids.In this paper,the free-falling of...In oil and gas well drilling operations,it is of great significance to accurately predict the drag coefficient and settling velocity of drill cuttings in non-Newtonian drilling fluids.In this paper,the free-falling of 172 groups of spheres and 522 groups of irregular-shaped sand particles in Newtonian/non-Newtonian fluids were investigated experimentally.It was found that the drag coefficient calculated based on Newtonian correlations can result in a significant error when the particle settles in the non-Newtonian fluid.Therefore,predictive models of drag coefficient were established respectively for different types of fluids.The validity of the proposed drag coefficient model of spheres was verified by comparing it with the previous works.On this basis,the drag coefficient model of irregular-shaped sand particles was established by introducing a shape factor.The models do not use the shape factor that requires detailed threedimensional shape and size information.Instead,two-dimensional geometric information(circularity)is obtained via image analysis techniques.The present new models predict the settling velocity of sand particles in the power-law fluid and Herschel-Bulkley fluid accurately with a mean relative error of5.03%and 6.74%,respectively,which verifies the accuracy of the model.展开更多
AIM： To establish the role of human T Cell Factor-4 （hTCF-4） gene exons 3-9 mutation status in association with sporadic rectal cancer with microsatellite instability （MSI）. METHODS： Microsatellite markers were ...AIM： To establish the role of human T Cell Factor-4 （hTCF-4） gene exons 3-9 mutation status in association with sporadic rectal cancer with microsatellite instability （MSI）. METHODS： Microsatellite markers were genotyped in 93 sporadic rectal cancer patients. Eleven cases were found to be high-frequency MSI （MSI-H）. Sequence analysis of the coding region of the exons 3-9 of hTCF-4 gene was carried out for the 11 MSI-H cases and 10 controls （5 microsatellite stability （MSS） cases and 5 cases with normal mucosa）. The sequencing and MSI identification were used. RESULTS： Several novel mutations and variants were revealed. In exon 4, one is a 4-position continuous alteration which caused amino acid change from Q131T and S132I （391insA, 392 G 〉 A, 393 A 〉 G and 395delC） and another nucleotide deletion （395delC） is present in MSI-H cases （5/10 and 4/10, respectively） but completely absent in the controls.CONCLUSION： Novel mutations in exon 4 of hTCF-4 gene were revealed in this study, which might be of importance in the pathogenesis of sporadic rectal cancer patients with MSI-H.展开更多
AIM： To identify the distribution of N-acetyltrasferase 2 （NAT2） polymorphism in Hebei Han Chinese and the effects of the polymorphism on the development of colorectal cancer.METHODS： We performed a hospital-based...AIM： To identify the distribution of N-acetyltrasferase 2 （NAT2） polymorphism in Hebei Han Chinese and the effects of the polymorphism on the development of colorectal cancer.METHODS： We performed a hospital-based case-control study of 237 healthy individuals and 83 colorectal cancer patients of Hebei Han Chinese. DNA was extracted from peripheral blood and cancer tissues. The genotypes of the polymorphisms were assessed by PCR-restriction fragment length polymorphism（RFLP）.RESULTS： There were four NAT2 alleles of WT, M1, M2,and M3 both in the healthy subjects and in the patients,and 10 genotypes of WT/WT, WT/M1, WT/M2, WT/M3,M1/M1, M1/M2, M1/M3, M2/M2, M2/M3, M3/M3. M2 allele was present in 15.61% of healthy subjects and 29.52% of patients （X^2 = 15.31, P〈0.0001）, and M3 allele was present in 30.59% of healthy subjects and 16.87% of patients （X^2 = 25.33, P〈0.0001）. There were more WT/M2 （X^2= 34.42, P〈0.0001, odd ratio= 4.99, 95%CI = 2.27-9.38）and less WT/M3 （X^2 = 3.80, P = 0.03） in the patients than in the healthy subjects. In 70.3% of the patients, there was a difference in NAT2 genotype between their tumors and blood cells. Patients had more WT/M2 （7.2 = 5.11,P = 0.02） and less M2/M3 （X^2= 4.27, P = 0.039） in their blood cells than in the tumors. Furthermore, 53.8% （7/13）of M2/M3 in tumors were from VVT/M2 of blood cells.CONCLUSION： There is a possible relationship between the NAT2 polymorphisms and colorectal cancer in Hebei Han Chinese. The genotype WT/M2 may be a risk factor for colorectal cancer.展开更多
BACKGROUND The metastasis of liver cancer to skeletal muscle is extremely rare compared to other sites.We herein report a case of rapidly developing skeletal metastases following liver transplantation due to primary l...BACKGROUND The metastasis of liver cancer to skeletal muscle is extremely rare compared to other sites.We herein report a case of rapidly developing skeletal metastases following liver transplantation due to primary liver cancer.CASE SUMMARY A 70-year-old male with underlying chronic hepatitis B virus infection was diagnosed with hepatocellular carcinoma(HCC),for which he underwent liver transplantation in 2014.Six years after receiving the transplant,pathological examination confirmed the presence of HCC without vascular invasion.He was admitted to the hospital with a rapidly growing mass on his right thigh.Ultrasound examination revealed a mixed echo mass in the lateral soft tissue of the middle part of the right femur.Magnetic resonance imaging showed heterogeneous iso-signal intensity on T1-weighted images and heterogeneous hyper-intensity on T2-weighted images compared to the surrounding muscles.Pathological examination of the ultrasound-guided needle biopsy specimen revealed that it was similar to the previously detected liver cancer;the diagnosis was metastasis of HCC.Surgical excision was performed.There were no other sites of metastasis,and the patient recovered well after surgery.CONCLUSION This report presents a rare case of skeletal metastasis following liver transplantation for HCC.The study suggests a possible role for skeletal muscle metastasis mechanisms,which should be the focus of future research.展开更多
Objective:To investigate the effects of developmental damage of hippocampal neurons in offspring rats induced by sevoflurane inhalation anesthesia during pregnancy and its related mechanisms.Methods:Eighteen pregnant ...Objective:To investigate the effects of developmental damage of hippocampal neurons in offspring rats induced by sevoflurane inhalation anesthesia during pregnancy and its related mechanisms.Methods:Eighteen pregnant female Sprague-Dawley(SD)rats were randomly divided into three experimental groups:the control group(intraperitoneal injection of 0.9%sodium chloride solution 100 mL),the sevoflurane inhalation anesthesia group(inhalation of 1 MAC sevoflurane for 6 h and intraperitoneal injection of 0.9%sodium chloride solution 100 mL),and the dexmedetomidine combined with sevoflurane inhalation anesthesia group(inhalation of 1 MAC sevoflurane for 6 h and intraperitoneal injection of dexmedetomidine 100 mL),with 6 rats in each group.On the day of birth,the offspring rats of each experimental group were randomly selected.And blood gas analysis was performed with left ventricular artery blood of each offspring.The expression of cleaved-caspase-3 in hippocampal neurons was measured by Western blot.The mRNA expressions of growth-associated protein-43(GAP-43)and neuronal nitric oxide synthase(nNOS)in hippocampus of offspring rats were detected by real-time RT-PCR.The protein expressions of GAP-43 and nNOS were tested by immunohistochemistry and Western blot.Results:Compared with the control group,cleaved-caspase-3 expression in hippocampal neurons of offspring rats in sevoflurane inhalation anesthesia group increased significantly.Cleaved-caspase-3 in hippocampal neurons of offspring after dexmedetomidine combined with sevoflurane inhalation anesthesia was dramatically lower than that in sevoflurane inhalation anesthesia group.Compared with the sevoflurane inhalation anesthesia group,dexmedetomidine combined with sevoflurane inhalation anesthesia could markedly up-regulate the mRNA and protein expressions of GAP-43 and nNOS.Conclusion:Dexmedetomidine can protect hippocampal neurons from developmental damage induced by sevoflurane inhalation anesthesia during pregnancy,which may be related to the up-regulation of the mRNA and protein expressions GAP-43 and nNOS.展开更多
The hot compression behavior and tensile strength after compression of a new Ni-Co-based superalloy produced using electron beam smelting layered(EBSL)solidification technology were investigated.Isothermal compression...The hot compression behavior and tensile strength after compression of a new Ni-Co-based superalloy produced using electron beam smelting layered(EBSL)solidification technology were investigated.Isothermal compression tests were performed at temperatures of 1120℃and 1150℃,with strain rates of 1 s^(-1) and 0.01 s^(-1),reaching a true strain of 0.51.Tensile strength was evaluated at room temperature.The results revealed that this EBSL technology accelerates dynamic recrystallization(DRX),without compromising the strength of alloy.A significant correlation between the volume fraction of DRX and the strain rate was observed,with higher fractions at lower strain rates,leading to higher tensile strength.Additionally,at the same strain rate,the specimens compressed at 1120℃exhibited higher tensile strength due to undissolvedγ′precipitates.After solution and aging heat treatment,the alloy maintained high tensile strength.The results suggested that the EBSL Ni-Co-based superalloy offers excellent prospects for practical applications.展开更多
The effect of long-term thermal exposure on the tensile behavior of a high W content nickel-based superalloy K416B was investigated.The microstructure and the deformation characteristics were observed by scanning elec...The effect of long-term thermal exposure on the tensile behavior of a high W content nickel-based superalloy K416B was investigated.The microstructure and the deformation characteristics were observed by scanning electron microscopy and transmission electron microscopy,and the phase transformation of the alloy during long-term thermal exposure was analyzed by X-ray diffraction patterns and differential thermal analysis.Results showed that after thermal exposure at 1000℃,the MC carbides in the K416 B alloy decomposed into M_(6)C.During tensile deformation,dislocations slipping inγmatrix crossed over the M_(6)C by Orowan bowing mechanism.With the increase of thermal exposure time,the secondary M_(6)C reduced greatly the yield strength of the alloy at room temperature.Meanwhile,the continuous distribution of the secondary M_(6)C with great brittleness in the grain boundary could become the main source of crack,which might change the fracture characteristic of the alloy from trans-granular to intergranular.展开更多
The intrinsic relationship between the microstructure evolution and thermal fatigue behavior of a single-crystal cobalt-base superalloy has been investigated. The thermal fatigue tests are performed cyclically between...The intrinsic relationship between the microstructure evolution and thermal fatigue behavior of a single-crystal cobalt-base superalloy has been investigated. The thermal fatigue tests are performed cyclically between room temperature and 1050 ℃ using V-notch plate specimens. Three states of thermal fatigue specimens are selected： the as-cast, solutionized as well as aged states. The solution treatment is carried out at 1260 ℃ for 24 h, which results in the dissolution of most of interdendritic continuous primary carbides. The subsequent aging treatment is carried out at 1100 ℃ for 100 h after solution treatment, resulting in the precipitation of a profusion of chain- and point-like M23C6 carbides in the matrix. The results indicate that the heat treatment can improve the thermal fatigue properties of the alloy and the effect of the solution treatment is more prominent than that of the aging treatment. The coarse and continuously distributed primary carbides in the as-cast state are changed into small and discontinuous distribution by heat treatment, which is the dominant factor in the improvement of thermal fatigue property. Additionally, the effect of oxidation behavior during thermal fatigue test on the thermal fatigue behavior is also studied.展开更多
Two experimental alloys containing diff erent contents of Ru were investigated to study the eff ect of Ru on the microstructural evolution during long-term thermal exposure.The increase in Ru promoted the formation of...Two experimental alloys containing diff erent contents of Ru were investigated to study the eff ect of Ru on the microstructural evolution during long-term thermal exposure.The increase in Ru promoted the formation of cubical,tiny,and evenγ′phase after full heat treatment.Moreover,the samples after full heat treatment were exposed at 1100℃ for diff erent time.Based on the classical model by Lifshitz,Slyozov,and Wagner,the coarsening ofγ′phase of the alloy containing 2.5 and3.5 wt.%Ru during the long-term aging was controlled by the interface reaction and diff usion,respectively.Theγ/γ′lattice misfi t was more negative with the increment of Ru addition,which induced the formation of stable raftedγ′phase in the alloy containing 3.5 wt.%Ru at the initiation of long-term aging.Besides,the increase in Ru reduced the diff usion coeffi cient,which could restrain theγ′phase coarsening.The lowerγ/γ′lattice misfi t of the alloy containing 2.5 wt.%Ru promoted the interface reaction,which induced the rapid coarsening ofγ′phase.Therefore,the increase in Ru improved the microstructural stability of the alloys.On the other hand,the raise of Ru induced"reverse partitioning"behavior,which was eff ective in suppressing the emergence of the topologically close-packed phase(TCP phase).The TCP phase occasionally occurred in the alloy containing 2.5 wt.%Ru,which was attributed to the high temperature and the supersaturation of theγmatrix.Moreover,the TCP phase was determined asμphase,which had a high concentration of Co,Re,Mo,and W.A sketch map describing the evolution of the TCP phase was also constructed.展开更多
The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results sho...The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.展开更多
It has been recently pointed out that the compositions of industrial alloys are originated from cluster-plus-glueatom structure units in solid solutions. Specifically for Ni-based superalloys, after properly grouping ...It has been recently pointed out that the compositions of industrial alloys are originated from cluster-plus-glueatom structure units in solid solutions. Specifically for Ni-based superalloys, after properly grouping the alloying elements into Al, Ni-like（Ni^-）, γ＇-forming Cr-like（Cr^-γ＇） and γ-forming Cr-like（Cr^-γ＇）, the optimal formula for single-crystal superalloys is established [Al–Ni^-12]（AlCr^-γ0：5Cr^-γ1：5）. The Co substitutions for Ni at the shell sites are conducted on the basis of the first-generation single-crystal superalloy AM3, formulated as [Al-Ni2-xCox]（Al1Ti0.25Ta0.25Cr1W0.25Mo0.25）, with x = 1.5, 1.75, 2 and 2.5（the corresponding weight percents of Co are 9.43, 11.0, 12.57 and 15.71, respectively）. The900 ℃ long-term aging follows the Lifshitz–Slyozov–Wagner theory（LSW theory）, and the Co content does not have noticeable influence on the coarsening rate of c0. The microstructure and creep behavior of the four（001） single-crystal alloys are investigated. The creep rupture lifetime is reduced as Co increases. The alloy with the lowest Co（9.43 Co） shows the longest lifetime of about 350 h at 1050 ℃/120 MPa, and all the samples show N-type rafting after creep tests.展开更多
基金supported by the Natural Science Foundation of Shandong Province,China (ZR2017MC033)National Key Research and Development Program of China (2023YFD1300504)Taishan Scholar Construction Foundation of Shandong Province,China (ts20190946)。
文摘In eukaryotic organisms,the most common internal modification of messenger RNA(m RNA)is N6-methyladenosine(m6A).This modification can be dynamically and reversibly controlled by specific enzymes known as m6A writers and erasers.The fat-mass and obesity-associated protein(FTO)catalyzes RNA demethylation and plays a critical role in various physiological and pathological processes.Our research identified dynamic alterations in both m6A and FTO during the assembly of primordial follicles,with an inverse relationship observed for m6A levels and nuclear-localized FTO expression.Application of Fto small interfering RNA(si RNA)altered the expression of genes related to cell proliferation,hormone regulation,and cell chemotaxis,and affected RNA alternative splicing.Overexpression of the full-length Fto gene led to changes in m6A levels,alternative splicing of Cdk5,cell proliferation,cell cycle progression,and proportion of primordial follicles.Conversely,overexpression of Fto lacking a nuclear localization signal(NLS)did not significantly alter m6A levels or primordial follicle assembly.These findings suggest that FTO,localized in the nucleus but not in the cytoplasm,regulates RNA m6A demethylation and plays a role in cell proliferation,cell cycle progression,and primordial follicle assembly.These results highlight the potential of m6A and its eraser FTO as possible biomarkers and therapeutic targets.
基金the financial support by the Defense Industrial Technology Development Program(No.JCKY2020130C024)the National Science and Technology Major Project,China(No.Y2019-Ⅶ-0011-0151)the Science Center for Gas Turbine Project(No.P2022-C-Ⅳ-002-001)。
文摘Cracks have consistently been a significant challenge limiting the development of additive manufactured nickel-based superalloys.It is essential to investigate the location of cracks and their forming mechanism.This study extensively examines the impact of solidification process,microstructural evolution,and stress concentration on crack initiation during direct energy deposition(DED).The results emphasize that the crack formation is significantly related to large-angle grain boundaries,rapid cooling rates.Cracks caused by large-angle grain boundaries and a fast-cooling rate predominantly appear near the edge of the deposited samples.Liquation cracks are more likely to form near the top of the deposited sample,due to the presence ofγ/γ'eutectics.The secondary dendritic arm and the carbides in the interdendritic regions can obstruct liquid flow during the final stage of solidification,which results in the formation of solidification cracks and voids.This work paves the way to avoid cracks in nickel-based superalloys fabricated by DED,thereby enhancing the performance of superalloys.
基金The Key Project of National Outstanding Youth Fund of China, No.39925032
文摘AIM： To clarify the expression change of Wnt-induced secreted protein-1 （WISP-l） in human rectal cancer and to determine whether it is correlated with invasion and metastasis of human rectal cancer.METHODS： Eighty-six paired samples of rectal cancer and surgically resected distant normal rectal tissue were collected and allocated into cancer group and control group respectively. WISP-1 mRNA was detected by relative quantitative real-time RT-PCR and WISP-1 protein was examined by immunohistochemical staining.RESULTS： WISP-1 gene overexpression was found in 65% （56/86） primary rectal cancers, 2-30 times that of the level in normal matched rectal tissues （P = 0.001）. The mRNA expression level was correlated with Duke＇s staging, histological differentiation grade and lymph node status. The WISP-1 protein expression was in accordance with mRNA expression level. The positive degree of immunohistochemical staining in the cancer group （1.40±0.35） was different from that in control group （1.04± 0.08, P 〈 0.001）. Moreover, in cancer group the positive staining degree in high-level mRNA cancers （1.46 ±0.37, n = 56） was higher than that in low-level mRNA （1.28 ± 0.28, n = 30, P = 0.018）.CONCLUSION： Aberrant levels of WISP-1 expression may play a role in rectal tumorigenesis. WISP-1 may be used as a specific clinical diagnosis and prognosis marker in rectal cancer.
基金supported by the Major State Basic Research and Development Program of China (No.2010CB631206)the National Natural Science Foundation of China (No.50931004)the Foundation of State Key Lab for Advanced Metals and Materials (No.2008zd-07)
文摘The recrystallization behavior of a single crystal nickel-base superalloy was investigated by shot peening and subsequent annealing. Two kinds of recrystallization microstructures, which are intensively dependent on the annealing temperature, are shown in the nickel-base superalloy after shot peening and subsequent annealing. Surface recrystallized grains are obtained when the superalloy is annealed at solution treatment temperature. The nucleation of recrystallization originates from the dendritic core, where rapid dissolution of γ＇ particles occurs. Cellular recrystallization is observed after annealing at lower temperatures. Cellular structures induced by high diffusivity of the moving boundary and more γ＇ particles dissolution led by residual stress are developed from the surface region. Recrystallized kinetics of the shot-peened alloy annealed at 1050°C accords with the Johnson-Mehl-Avrami-Kolmogorov equation. The low Avrami exponent is caused by the inhomogeneous distribution of stored energy, the decreasing of stored energy during recovery, and the strong resistance of boundary migration by γ＇ particles.
基金Supported by grants from the Cancer Research Coordinating Committee of the University of California, United Stated.
文摘AIM： To study the relationship between particularly interesting new cysteine-histidine rich protein （PINCH） expression and clinicopathological factors in Chinese colorectal cancer patients. METHODS： The expression of PINCH was examined by immumohistochemistry in 141 samples of primary colorectal adenocarcinoma and 92 normal samples of colorectal mucosa. Eighty of the cases had both primary tumour and normal mucosa from the same patients. RESULTS： PINCH was expressed in the stroma of normal mucosa and tumours. PINCH expression in tumourassociated stroma was increased compared to normal mucosa in both unmatched cases （n = 141, x^2 = 85.79, df = 3, P〈 0.0001） and matched cases （n =80, x^2= 45.86, df= 3, P〈 0.0001）. Among 135 tumours with visible invasive margin, 86 （64%） showed stronger PINCH expression at the invasive margin than in the intratumoural stroma. The frequency of PINCH strong expression in mucinous and signet-ring cell carcinomas was higher （52%） compared to non-mucinous carcinomas （29%, x^2=5.13, P= 0.02）. We did not find that PINCH expres- sion was related to patient＇s gender, age, tumour location, tumour size, gross status, histological type, differentiation, invasion depth, lymph node status and Dukes＇ stage （P 〉 0.05）.CONCLUSION： The expression of PINCH was upregulated in colorectal cancers, and especially at the margin of tumours, and further was related to mucinous and signet-ring cell carcinomas. The results suggest that expression of PINCH may be involved in the tumourigenesis and aggressiveness of colorectal cancers.
基金financially supported by the National Natural Science Foundation of China(Grant No.51974090,51474073)
文摘With ongoing development of oil exploration and techniques,there is a significant need for improved well control strategies and formation pressure prediction methods.In this paper,a gas-liquid transient drift flow model was established according to the gas-liquid two-phase flow characteristics during the gas kick.A Roe scheme was used for numerical calculation based on the finite volume method.The changes of bottom-hole pressure,casing pressure,the development law of cross-sectional gas holdup,and gas velocity,along with the vertical well depth,were analyzed through simulation examples.The time-series characteristics of mud pit gain were obtained by adjusting the formation parameter.The complex nonlinear mapping relationship between the formation parameters and the mud pit gain was established.The long short-term memory network(LSTM)of deep learning was used to obtain a formation pressure inversion when the blowout is out of control and the well cannot be shut-in.Experimental data from a well were used to verify the gas-liquid two-phase transient drift flow model based on the finite volume method,demonstrating that this method is reliable,with greatly improved prediction accuracy.This approach provides theoretical support for the early monitoring of gas kick during drilling,and for well-killing design and construction after uncontrolled blowout.
基金Supported by grants from the Swedish Cancer Foundation and the Health Research Council in the South-East of Sweden
文摘AIM： To examine whether polymorphisms in SULTIA1 and GSTP1 genes contribute to colorectal cancer development and whether they are associated with clinicopathological variables are not well identified. METHODS： We examined the genotypes of 125 colorectal cancer patients and 666 healthy controls in a Swedish population by using PCR-restriction fragment length polymorphism （RFLP）. RESULTS： SULTIA1 ＊2/＊2 genotype （OR = 2.49, 95%CI = 1.48-4.19, P = 0.0002） and ＊2 allele （OR = 1.56, 95%CI =1.16-2.10, P = 0.002） had an effect on colorectal cancer susceptibility, while GSTP1 genotype was without effect. However, GSTP1 G-type predicted a worse prognosis in the patients independently of gender, age, Dukes＇ stage, growth pattern, and differentiation （P = 0.03）.CONCLUSION： Polymorphism in SULTIA1 may predispose to colorectal cancer and GSTP1 may be a biological indicator of prognosis in the patients.
基金financially supported by the National Basic Research Program of China(Nos.2010CB631200 and 2010CB631206)the National Natural Science Foundation of China(No.51701212,No.50931004,No.51571196,No.51601192 and No.51671188)+4 种基金the State Key Laboratory of Solidification Processing in NWPU(SKLSP201747)Liaoning Provincial Natural Science Foundation of China(No.2019-MS-336)the Key Regional Project of Science and Technology Service Network Program,Chinese Academy of Sciences(No.KFJ-STS-QYZX-079)the Youth Innovation Promotion Association Project,Chinese Academy of Sciences(2020)the National Science and Technology Major Project(J2019-VI-0018-0133)。
文摘K416B Ni-based superalloy with high W content has good high temperature properties and low cost,which has a great development potential.To investigate the room temperature tensile property and the deformation feature of K416B superalloy,tensile testing at room temperature was carried out,and optical microscopy (OM),scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the deformation and damage mechanisms.Results show that the main room temperature tensile deformation features of the K416B nickel-based superalloy are dislocations slipping in the matrix and shearing into γ’ phase.The <110> super-dislocations shearing into γ’ phase can form the anti-phase boundary two coupled (a/2)<110> partial-dislocations or decompose into the configuration of two (a/3)<112> partial dislocations plus stacking fault.In the later stage of tensile testing,the slip-lines with different orientations are activated in the grain,causing the stress concentration in the regions of block carbide or the porosity,and cracks initiate and propagate along these regions.
基金financially supported by the National Natural Science Foundation of China(Grant no.51674087,51974090)the National Science and Technology Major Project of the Ministry of Science and Technology of China(grant number 2017ZX05009003)。
文摘In oil and gas well drilling operations,it is of great significance to accurately predict the drag coefficient and settling velocity of drill cuttings in non-Newtonian drilling fluids.In this paper,the free-falling of 172 groups of spheres and 522 groups of irregular-shaped sand particles in Newtonian/non-Newtonian fluids were investigated experimentally.It was found that the drag coefficient calculated based on Newtonian correlations can result in a significant error when the particle settles in the non-Newtonian fluid.Therefore,predictive models of drag coefficient were established respectively for different types of fluids.The validity of the proposed drag coefficient model of spheres was verified by comparing it with the previous works.On this basis,the drag coefficient model of irregular-shaped sand particles was established by introducing a shape factor.The models do not use the shape factor that requires detailed threedimensional shape and size information.Instead,two-dimensional geometric information(circularity)is obtained via image analysis techniques.The present new models predict the settling velocity of sand particles in the power-law fluid and Herschel-Bulkley fluid accurately with a mean relative error of5.03%and 6.74%,respectively,which verifies the accuracy of the model.
基金the National Natural Science Foundation of China, No. 39925032
文摘AIM： To establish the role of human T Cell Factor-4 （hTCF-4） gene exons 3-9 mutation status in association with sporadic rectal cancer with microsatellite instability （MSI）. METHODS： Microsatellite markers were genotyped in 93 sporadic rectal cancer patients. Eleven cases were found to be high-frequency MSI （MSI-H）. Sequence analysis of the coding region of the exons 3-9 of hTCF-4 gene was carried out for the 11 MSI-H cases and 10 controls （5 microsatellite stability （MSS） cases and 5 cases with normal mucosa）. The sequencing and MSI identification were used. RESULTS： Several novel mutations and variants were revealed. In exon 4, one is a 4-position continuous alteration which caused amino acid change from Q131T and S132I （391insA, 392 G 〉 A, 393 A 〉 G and 395delC） and another nucleotide deletion （395delC） is present in MSI-H cases （5/10 and 4/10, respectively） but completely absent in the controls.CONCLUSION： Novel mutations in exon 4 of hTCF-4 gene were revealed in this study, which might be of importance in the pathogenesis of sporadic rectal cancer patients with MSI-H.
文摘AIM： To identify the distribution of N-acetyltrasferase 2 （NAT2） polymorphism in Hebei Han Chinese and the effects of the polymorphism on the development of colorectal cancer.METHODS： We performed a hospital-based case-control study of 237 healthy individuals and 83 colorectal cancer patients of Hebei Han Chinese. DNA was extracted from peripheral blood and cancer tissues. The genotypes of the polymorphisms were assessed by PCR-restriction fragment length polymorphism（RFLP）.RESULTS： There were four NAT2 alleles of WT, M1, M2,and M3 both in the healthy subjects and in the patients,and 10 genotypes of WT/WT, WT/M1, WT/M2, WT/M3,M1/M1, M1/M2, M1/M3, M2/M2, M2/M3, M3/M3. M2 allele was present in 15.61% of healthy subjects and 29.52% of patients （X^2 = 15.31, P〈0.0001）, and M3 allele was present in 30.59% of healthy subjects and 16.87% of patients （X^2 = 25.33, P〈0.0001）. There were more WT/M2 （X^2= 34.42, P〈0.0001, odd ratio= 4.99, 95%CI = 2.27-9.38）and less WT/M3 （X^2 = 3.80, P = 0.03） in the patients than in the healthy subjects. In 70.3% of the patients, there was a difference in NAT2 genotype between their tumors and blood cells. Patients had more WT/M2 （7.2 = 5.11,P = 0.02） and less M2/M3 （X^2= 4.27, P = 0.039） in their blood cells than in the tumors. Furthermore, 53.8% （7/13）of M2/M3 in tumors were from VVT/M2 of blood cells.CONCLUSION： There is a possible relationship between the NAT2 polymorphisms and colorectal cancer in Hebei Han Chinese. The genotype WT/M2 may be a risk factor for colorectal cancer.
文摘BACKGROUND The metastasis of liver cancer to skeletal muscle is extremely rare compared to other sites.We herein report a case of rapidly developing skeletal metastases following liver transplantation due to primary liver cancer.CASE SUMMARY A 70-year-old male with underlying chronic hepatitis B virus infection was diagnosed with hepatocellular carcinoma(HCC),for which he underwent liver transplantation in 2014.Six years after receiving the transplant,pathological examination confirmed the presence of HCC without vascular invasion.He was admitted to the hospital with a rapidly growing mass on his right thigh.Ultrasound examination revealed a mixed echo mass in the lateral soft tissue of the middle part of the right femur.Magnetic resonance imaging showed heterogeneous iso-signal intensity on T1-weighted images and heterogeneous hyper-intensity on T2-weighted images compared to the surrounding muscles.Pathological examination of the ultrasound-guided needle biopsy specimen revealed that it was similar to the previously detected liver cancer;the diagnosis was metastasis of HCC.Surgical excision was performed.There were no other sites of metastasis,and the patient recovered well after surgery.CONCLUSION This report presents a rare case of skeletal metastasis following liver transplantation for HCC.The study suggests a possible role for skeletal muscle metastasis mechanisms,which should be the focus of future research.
基金This study was supported by the Shenyang Science and Technology Project in 2018(Grant No.18-014-4-32).
文摘Objective:To investigate the effects of developmental damage of hippocampal neurons in offspring rats induced by sevoflurane inhalation anesthesia during pregnancy and its related mechanisms.Methods:Eighteen pregnant female Sprague-Dawley(SD)rats were randomly divided into three experimental groups:the control group(intraperitoneal injection of 0.9%sodium chloride solution 100 mL),the sevoflurane inhalation anesthesia group(inhalation of 1 MAC sevoflurane for 6 h and intraperitoneal injection of 0.9%sodium chloride solution 100 mL),and the dexmedetomidine combined with sevoflurane inhalation anesthesia group(inhalation of 1 MAC sevoflurane for 6 h and intraperitoneal injection of dexmedetomidine 100 mL),with 6 rats in each group.On the day of birth,the offspring rats of each experimental group were randomly selected.And blood gas analysis was performed with left ventricular artery blood of each offspring.The expression of cleaved-caspase-3 in hippocampal neurons was measured by Western blot.The mRNA expressions of growth-associated protein-43(GAP-43)and neuronal nitric oxide synthase(nNOS)in hippocampus of offspring rats were detected by real-time RT-PCR.The protein expressions of GAP-43 and nNOS were tested by immunohistochemistry and Western blot.Results:Compared with the control group,cleaved-caspase-3 expression in hippocampal neurons of offspring rats in sevoflurane inhalation anesthesia group increased significantly.Cleaved-caspase-3 in hippocampal neurons of offspring after dexmedetomidine combined with sevoflurane inhalation anesthesia was dramatically lower than that in sevoflurane inhalation anesthesia group.Compared with the sevoflurane inhalation anesthesia group,dexmedetomidine combined with sevoflurane inhalation anesthesia could markedly up-regulate the mRNA and protein expressions of GAP-43 and nNOS.Conclusion:Dexmedetomidine can protect hippocampal neurons from developmental damage induced by sevoflurane inhalation anesthesia during pregnancy,which may be related to the up-regulation of the mRNA and protein expressions GAP-43 and nNOS.
基金The authors appreciate the financial support from the National Key R&D Program of China(2019YFA0705300)the National Science and Technology Major Project(J2019-VI-0006-0120)+1 种基金the Youth Innovation Promotion Association,CAS(No.2023202)the Natural Science Foundation Project of Liaoning Province(No.2023-MS-024).
文摘The hot compression behavior and tensile strength after compression of a new Ni-Co-based superalloy produced using electron beam smelting layered(EBSL)solidification technology were investigated.Isothermal compression tests were performed at temperatures of 1120℃and 1150℃,with strain rates of 1 s^(-1) and 0.01 s^(-1),reaching a true strain of 0.51.Tensile strength was evaluated at room temperature.The results revealed that this EBSL technology accelerates dynamic recrystallization(DRX),without compromising the strength of alloy.A significant correlation between the volume fraction of DRX and the strain rate was observed,with higher fractions at lower strain rates,leading to higher tensile strength.Additionally,at the same strain rate,the specimens compressed at 1120℃exhibited higher tensile strength due to undissolvedγ′precipitates.After solution and aging heat treatment,the alloy maintained high tensile strength.The results suggested that the EBSL Ni-Co-based superalloy offers excellent prospects for practical applications.
基金financially supported by the National Basic Research Program of China(Nos.2010CB631200 and 2010CB631206)the National Natural Science Foundation of China(Nos.51701212,50931004,51571196,51601192 and 51671188)+1 种基金the State Key Laboratory of Solidification Processing in NWPU(SKLSP201747)the Liaoning Provincial Natural Science Foundation of China(No.2019-MS-336)。
文摘The effect of long-term thermal exposure on the tensile behavior of a high W content nickel-based superalloy K416B was investigated.The microstructure and the deformation characteristics were observed by scanning electron microscopy and transmission electron microscopy,and the phase transformation of the alloy during long-term thermal exposure was analyzed by X-ray diffraction patterns and differential thermal analysis.Results showed that after thermal exposure at 1000℃,the MC carbides in the K416 B alloy decomposed into M_(6)C.During tensile deformation,dislocations slipping inγmatrix crossed over the M_(6)C by Orowan bowing mechanism.With the increase of thermal exposure time,the secondary M_(6)C reduced greatly the yield strength of the alloy at room temperature.Meanwhile,the continuous distribution of the secondary M_(6)C with great brittleness in the grain boundary could become the main source of crack,which might change the fracture characteristic of the alloy from trans-granular to intergranular.
基金supported by the National Natural Science Foundation of China (Nos.51331005,51601192,51671188 and 11332010)the High Technology Research and Development Program of China (No.2014AA041701)
文摘The intrinsic relationship between the microstructure evolution and thermal fatigue behavior of a single-crystal cobalt-base superalloy has been investigated. The thermal fatigue tests are performed cyclically between room temperature and 1050 ℃ using V-notch plate specimens. Three states of thermal fatigue specimens are selected： the as-cast, solutionized as well as aged states. The solution treatment is carried out at 1260 ℃ for 24 h, which results in the dissolution of most of interdendritic continuous primary carbides. The subsequent aging treatment is carried out at 1100 ℃ for 100 h after solution treatment, resulting in the precipitation of a profusion of chain- and point-like M23C6 carbides in the matrix. The results indicate that the heat treatment can improve the thermal fatigue properties of the alloy and the effect of the solution treatment is more prominent than that of the aging treatment. The coarse and continuously distributed primary carbides in the as-cast state are changed into small and discontinuous distribution by heat treatment, which is the dominant factor in the improvement of thermal fatigue property. Additionally, the effect of oxidation behavior during thermal fatigue test on the thermal fatigue behavior is also studied.
基金financially supported by the National Science and Technology Major Project(No.2017-VI-0002–0072)the National Key R&D Program of China(No.2017YFA0700704)+1 种基金the National Natural Science Foundation of China(Nos.51671188,51601192 and 51701210)the Youth Innovation Promotion Association,Chinese Academy of Sciences and State Key Lab of Advanced Metals and Materials Open Fund(No.2018-Z07)。
文摘Two experimental alloys containing diff erent contents of Ru were investigated to study the eff ect of Ru on the microstructural evolution during long-term thermal exposure.The increase in Ru promoted the formation of cubical,tiny,and evenγ′phase after full heat treatment.Moreover,the samples after full heat treatment were exposed at 1100℃ for diff erent time.Based on the classical model by Lifshitz,Slyozov,and Wagner,the coarsening ofγ′phase of the alloy containing 2.5 and3.5 wt.%Ru during the long-term aging was controlled by the interface reaction and diff usion,respectively.Theγ/γ′lattice misfi t was more negative with the increment of Ru addition,which induced the formation of stable raftedγ′phase in the alloy containing 3.5 wt.%Ru at the initiation of long-term aging.Besides,the increase in Ru reduced the diff usion coeffi cient,which could restrain theγ′phase coarsening.The lowerγ/γ′lattice misfi t of the alloy containing 2.5 wt.%Ru promoted the interface reaction,which induced the rapid coarsening ofγ′phase.Therefore,the increase in Ru improved the microstructural stability of the alloys.On the other hand,the raise of Ru induced"reverse partitioning"behavior,which was eff ective in suppressing the emergence of the topologically close-packed phase(TCP phase).The TCP phase occasionally occurred in the alloy containing 2.5 wt.%Ru,which was attributed to the high temperature and the supersaturation of theγmatrix.Moreover,the TCP phase was determined asμphase,which had a high concentration of Co,Re,Mo,and W.A sketch map describing the evolution of the TCP phase was also constructed.
基金supported financially by the National Natural Science Foundation of China (Nos. 11332010,51671189 and 51701210)the Project from China Huaneng Group Co. Ltd. (No. ZD-15-HJK02)
文摘The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.
基金financially supported by the National Key Research and Development Program of China (Grant No. 2016YFB0701401)the National Natural Science Foundation of China (No. 11674045)
文摘It has been recently pointed out that the compositions of industrial alloys are originated from cluster-plus-glueatom structure units in solid solutions. Specifically for Ni-based superalloys, after properly grouping the alloying elements into Al, Ni-like（Ni^-）, γ＇-forming Cr-like（Cr^-γ＇） and γ-forming Cr-like（Cr^-γ＇）, the optimal formula for single-crystal superalloys is established [Al–Ni^-12]（AlCr^-γ0：5Cr^-γ1：5）. The Co substitutions for Ni at the shell sites are conducted on the basis of the first-generation single-crystal superalloy AM3, formulated as [Al-Ni2-xCox]（Al1Ti0.25Ta0.25Cr1W0.25Mo0.25）, with x = 1.5, 1.75, 2 and 2.5（the corresponding weight percents of Co are 9.43, 11.0, 12.57 and 15.71, respectively）. The900 ℃ long-term aging follows the Lifshitz–Slyozov–Wagner theory（LSW theory）, and the Co content does not have noticeable influence on the coarsening rate of c0. The microstructure and creep behavior of the four（001） single-crystal alloys are investigated. The creep rupture lifetime is reduced as Co increases. The alloy with the lowest Co（9.43 Co） shows the longest lifetime of about 350 h at 1050 ℃/120 MPa, and all the samples show N-type rafting after creep tests.
