Effect of aging heat treatment on the grain boundary microstructure and creep properties of a cast Ni-based superalloy was investigated. With increasing aging temperature from 750 to 1000 °C,
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carbides along the grain boundaries evolve from fine distributed block, continuous film into the coarse discrete block. Moreover, the
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carbides are mainly enveloped within
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′ layers along grain boundaries during 1000 °C aging. Creep rupture lifetime and elongation at 760 °C and 645 MPa are improved with increasing the aging temperature. In particular, the creep rupture lifetime of the specimens aging at 1000 °C is one order of magnitude higher than that of the specimens aging at 750 °C. The enhancement of ductility induced by the
γ
′ envelopes plays a significant role in the improvement of creep rupture lifetime.
The influences of heat treatment and test condition on the microstructure and stress rupture properties of a Ni–Mo–Cr–Fe base corrosion-resistant superalloy have been investigated in this paper. ...Optical microscope and scanning electron microscope were employed for the microstructure observation, and X-ray diffraction, electron probe micro-analyzer, and transmission electron microscope were used for phase determination. It was found that the grain size increased and the volume fractions of initial M
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C carbides decreased along with the increase in solution treatment temperature. When tested at 650 °C/320 MPa, the stress rupture lives decreased with the increase in solution treatment temperature, but the stress rupture lives increased slightly at first and then decreased for the samples solution heat treated at 1220 °C when tested at 700 °C/240 MPa. The elongations showed the descendent trends under these two conditions. The stress rupture life and elongation for the aged samples all showed a noticeable improvement at 650 °C/320 MPa, but there was no noticeable improvement at 700 °C/240 MPa. The reasons can be attributed to the grain size, test conditions, and the initial and secondary carbides.
Background Myocardial infarction (MI) is a significant cause of heart failure. Current therapies are limited and, therefore, the development of novel revascularization methods is potentially ...important. We investigated whether hepatocyte growth factor (HGF), expressed by genetically modified mesenchymal stromal cells (MSC), in combination with granulocyte colony-stimulating factor (G-CSF), exhibited a synergistic therapeutic benefit, as measured 8 weeks after MI induction in a rat model. Methods Four weeks after MI, rats were randomly divided into a control group ( n =11), HGF group (Adenovirus vector carrying human HGF (Ad-HGF)-transfected MSC transplanted into the infarct zone; n =11), G-CSF group (intraperitoneal injection with G-CSF; n =11), and HGF+G-CSF group (Ad-HGF-transfected MSC transplanted into the infarct zone and intraperitoneal injection with G-CSF; n =11). Four weeks later, hearts were analyzed for endothelial cell density and angiogenesis, ventricular geometry, myocardial function and levels of VCAM-1 and MMP-9 protein. Results The HGF+G-CSF group exhibited improved left ventricular systolic and diastolic function and experienced less adverse ventricular remodeling, as manifested by decreased left ventricular dilatation and increased border zone wall thickness. Angiogenesis was significantly enhanced in HGF+G-CSF rats by inducing the proliferation of endothelial cells. Furthermore, HGF induced expression of VCAM-1, and HGF treatment together with G-CSF synergistically stimulated MMP-9 expression in ischemic hearts. Discussion The combination of G-CSF and HGF exhibited a significant synergistic effect and enhanced myocardial endothelial density, angiogenesis, geometric preservation and heart function in an ischemic cardiomyopathy model.
To investigate the effects of different X-ray doses on the expression of nuclear factor-kappaB (NF-kappaB) P65 in human oral squamous cell carcinoma cell (OSCC) line and the relationship between ...NF-kappaB P65 and radiation-induced OSCC cell line apoptosis.
The squamous cell carcinoma of Tca8113 cell was cultivated in the 37 degrees C, 5% CO2 incubator after recovery. The experiment samples were divided into six groups (control group, 2, 4, 6, 8, 10 Gy). After growing to logarithm period, Tca8113 cells were irradiated using above-mentioned X-ray doses. The immunocyteochemistry and Western blot were used to detect the expression of NF-kappaB P65 after irradiation in various times (1, 3, 6, 10, 24, 48 h). The apoptosis rates under different radiotherapy dose were detected by flow cytometer and TDT-mediated dUTP-biotin nick end labeling (TUNEL).
Compared with the control group, cytoplasm expression of P65 under different X-ray doses had statistically significant differences (P < 0.05). While the cytoplasm P65 pro
To detect the expression of p65, a subunit of NF-κB proteins, and apoptosis after adenoid cystic carcinoma cells(ACC-2) irradiated by high energy X-ray, and to investigate the interaction between ...them.
ACC-2 cells were cultured and then irradiated by high energy X-ray of different dose(2, 4, 6, 8,10Gy). At the next six time points(1, 3, 6, 10, 24, 48h), the expression of p65 protein in cytoplasm and nucleus was detected by immunocytochemistry and Western blotting. The apoptotic cells were counted by flow cytometry and then observed by TUNEL technique. The data of radiant intensity and apoptotic rate were statistically analyzed by Spearman method with SPSS11.5 software package.
In ordinary condition, p65 protein seldom appeared in the nucleus, and mostly stained in the cytoplasm by immunocytochemistry. After irradiation, the protein was observed around the nuclear. Then it went through the nuclear membrane more and more as time going on, finally to the center of the nucleus. The quantity of p65 among the total
In order to speed up rural domestic refuse resources utilization, intermittent aeration and continuous aeration were applied to treat rural domestic refuse after anaerobic fermentation. Three kinds ...of refuse were selected on base of fermentative age, i.e. three months, five months and seven months. Results showed that aeration could remove water and organic materials of the refuse effectively. Points of view on aeration, continuous aeration was better than intermittent aeration, and on the other side, water removal rate increased with ventilation and decreased with fermentative age in the condition of intermittent aeration. On organic materials removal point, it was affected by fermentative age significantly, i. e. increase of fermentative age could resulted in decrease in the removal efficiency. In conclusion, intermittent aeration of 0.06 m3/(min x m3) was considered to be feasible for treatment. The water removal efficiency of three months, five months and seven months fermentative age refuse could be up t
The catalytic oxidation of aniline was evaluated to provide the foundation for risk-based treatment of aniline-contaminated solid-waste using Fenton reagent (catalyzed hydrogen peroxide). The ...operating conditions of Fenton reaction were investigated and the factors of the chemical treatment were analyzed. The optimal conditions were following: 1.1 mL H2O2 per gram of dried solid waste, V (H2O2) 0.5-1.0 mL x min(-1), addition of Fenton reagent twice or three times at pH = 3.0 in 50 grams of waste, and the aniline removal rate is over 99.86% for 30 min reaction after reagent addition. Furthermore, mechanisms of affecting factors in solid-waste were analyzed; the key and controlling steps of reactions were expounded in the system, which provided safeguard for further treatment ranging from stabilization and solidification to landfill.
To investigate the oxidation behavior of a nickel-based superalloy with high hafnium content (1.34wt％), this study performed iso-thermal oxidation tests at 900, 1000, and 1100℃ for up to 200 h. X-ray ...diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy were applied to study the oxidation behavior. The weight gain of the high Hf nickel-based superalloy exhibited a parabola-like curve, and no spallation of the oxide scale was observed during the oxidation tests. The alloy presented excellent oxidation resistance, and no HfO2 was observed in the oxide scale at 900℃. With the increase of the oxidation temperature to 1000℃, HfO2 particles formed in the spinel phases of the scale, and "peg-like" HfO2 was observed within and beneath the inner layer of Al2O3 after 200 h. As the oxidation temper-ature rose to 1100℃, "peg-like" HfO2 was observed at the early stage of the oxidation test (within 25 h). The formation mechanism of HfO2 and its impact on oxidation resistance were investigated based on the analysis of the oxidation test results at different temperatures.
Objective To investigate if co-transfection of human bone morphogenetic protein 2 (BMP-2, BMP2 ) and human fibroblast growth factor 2 (FGF2, FGF2 ) via chitosan nanoparticles promotes osteogenesis in ...human adipose tissue-derived stem cells (ADSCs) in vitro . Materials and Methods Recombinant BMP2 and/or FGF2 expression vectors were constructed and packaged into chitosan nanoparticles. The chitosan nanoparticles were characterized by atomic force microscopy. Gene and protein expression levels of BMP-2 and FGF2 in ADSCs in vitro were evaluated by real-time polymerase chain reaction (PCR), western blot, and enzyme-linked immunosorbent assay. Osteocalcin (OCN) and bone sialoprotein (BSP) gene expression were also evaluated by real-time PCR to assess osteogenesis. Results The prepared chitosan nanoparticles were spherical with a relatively homogenous size distribution. The BMP2 and FGF2 vectors were successfully transfected into ADSCs. BMP-2 and FGF2 mRNA and protein levels were significantly up-regulated in the co-transfection group compared with the control group. OCN and BSP mRNA levels were also significantly increased in the co-transfection group compared with cells transfected with BMP2 or FGF2 alone, suggesting that co-transfection significantly enhanced osteogenesis. Conclusions Co-transfection of human ADSCs with BMP2/FGF2 via chitosan nanoparticles efficiently promotes the osteogenic properties of ADSCs in vitro .
To explore the possible association of different polymorphic forms of human alpha-estrogen receptor (ER-alpha) and aryl hydrocarbon receptor gene (Ahr) with the risk to senile dementia in farmers in ...Shanghai suburb.
Senile dementia patients (n=52) were examined for ER-alpha and Ahr gene polymorphism genotyping. Healthy individuals (n=125) in the same area were selected as a community control group. Two polymorphic loci, Pvu II locus and Xba I locus, of human ER- a gene were investigated by a PCR-RFLP-based procedure. The population frequencies of two polymorphic loci in exon 10 of Ahr gene, G1721A (R554K) and G1768A (V570I) were compared between patients and healthy controls using an allele-specific PCR (AS-PCR) procedure.
The mutant allele frequencies of ER-alpha gene in the AD group were significantly higher than those in the control group (P=0.023, OR=2.94, 95 % CI 1.13-7.71 for Pvu II locus; P=0.046, OR=2.28, 95 % CI 1.003-5.17 for Xba I locus). The mutant allele frequencies among female AD patients were higher than those in the female controls (P=0.016, OR=3.68, 95 % CI 1.22-11.08 for Pvu II locus, P=0.029, OR=2.95, 95 % CI 1.10-7.94 for Xba I locus). The mutant form, neither in the homozygous, nor in the heterozygous form was detected at the locus of Ahr G1768A in a normal local population. No significant difference of Ahr genotype frequency at locus G1721A was noticed between the patients and healthy individuals.
The distribution of ER polymorphisms was significantly different between Chinese and some other ethnic populations. The results suggested that ER-alpha gene polymorphisms might be related to the individual susceptibility to AD, especially in the females. However, it did not support the association of Ahr gene polymorphism with higher risk of senile dementia.
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