The microstructure evolution and mechanical properties of a T8-aged Al-Cu-Li alloy with increased pre-deformation(0-15%) were investigated,revealing the microstructure-strength relationship and the intrinsic strengthe...The microstructure evolution and mechanical properties of a T8-aged Al-Cu-Li alloy with increased pre-deformation(0-15%) were investigated,revealing the microstructure-strength relationship and the intrinsic strengthening mechanism.The results show that increasing the pre-deformation levels remarkably improves the strength of the alloy but deteriorates its ductility.Dislocations introduced by pre-deformation effectively suppress the formation of Guinier-Preston(GP) zones and provide more nucleation sites for T1 precipitates.This leads to more intensive and finer T1 precipitates in the samples with higher pre-deformation levels.Simultaneously,the enhanced precipitation of T1 precipitates and inhibited formation of GP zones cause the decreases in number and sizes of θ′ precipitates.The quantitative descriptions of the strength contributions from different strengthening mechanisms reveal that strengthening contributions from T1 and θ′ precipitates decrease with increasing pre-deformation.The reduced diameters of T1 precipitates are primarily responsible for their weakened strengthening effects.Therefore,the improved strength of the T8-aged Al-Cu-Li alloy is mainly attributed to the stronger strain hardening from the increased pre-deformation levels.展开更多
Objective: To discuss the expression and significance of angiostatin, vascular endothelial growth factor and matrix metalloproteinase-9 in the brain tissue of diabetic rats with ischemia reperfusion. Methods: A total ...Objective: To discuss the expression and significance of angiostatin, vascular endothelial growth factor and matrix metalloproteinase-9 in the brain tissue of diabetic rats with ischemia reperfusion. Methods: A total of 60 male Wistar rats were randomly divided into the normal group, sham group, diabetic cerebral infarction group and single cerebral infarction group according to the random number table, with 15 rats in each group. The high sucrose diet and intraperitoneal injection of streptozotocin were performed for the modeling of diabetic rats, while the thread-occlusion method was employed to build the model of cerebral ischemia reperfusion. The immunohistochemical staining was performed to detect the expression of angiostatin, vascular endothelial growth factor(VEGF) and matrix metalloproteinase-9(MMP-9) in the brain tissue. Results: The expression of angiostatin after the reperfusion in the brain tissue of rats in the single cerebral infarction group and diabetic cerebral infarction group was increased 6 h after the reperfusion, reached to the peak on 1 d and then decreased gradually. The expression of angiostatin in the diabetic cerebral infarction group 6 h, 1 d, 3 d and 7 d after the reperfusion was significantly higher than that in the single cerebral infarction group(P<0.05). VEGF began to be increased 1 h after the reperfusion in the single cerebral infarction group and diabetic cerebral infarction group, reached to the peak at 6 h and then decreased gradually. The expression of VEGF in the diabetic cerebral infarction group at each time point after the reperfusion was significantly lower than that in the single cerebral infarction group(P<0.05). MMP-9 began to be be increased 1 h after the reperfusion in the single cerebral infarction group and diabetic cerebral infarction group, reached to the peak on 1 d and then decreased gradually. The expression of MMP-9 in the diabetic cerebral infarction group at each time point after the reperfusion was significantly higher than that in the single cerebral infarction group(P<0.05). Conclusions: The high glucose environment in which the diabetic cerebral infarction is occurred is to induce the formation of MMP-9 at first and then activate and increase the expression of angiostatin. Afterwards, the expression of VEGF is inhibited, resulting in the poor angiogenesis after cerebral infarction, which thus makes the injury of brain tissue after cerebral infarction even worse than the non-diabetes mellitus.展开更多
2195 Al-Li alloy was deformed through extrusion followed by cold-rolling.The textures of the extruded plate and cold-rolled sheet after solutionization were investigated.The longitudinal strength and precipitates afte...2195 Al-Li alloy was deformed through extrusion followed by cold-rolling.The textures of the extruded plate and cold-rolled sheet after solutionization were investigated.The longitudinal strength and precipitates after T8 aging were measured and observed,respectively.Compared to those in the sheet,T1(Al2 Cu Li)precipitates in the extruded plate after T8 aging are non-uniform,and their incubation time is shorter.The extruded plate after solutionization is not recrystallized and contains 55.28%deformation textures of Brass and S.In the cold-rolled sheet after solutionization,massive recrystallization occurs and S component disappears.Due to the higher fraction of Brass and S textures with higher Schmid factor and lower equivalent sliding system number,the extruded plate possesses an yield strength not higher or even lower,but a tensile strength higher,than the cold-rolled sheet after solutionization.In addition,during the aging after pre-stretch,these textures promote T1 precipitation on preferred sliding planes of cold-rolled sheet and cause its higher yield strength and tensile strength after T8 aging.展开更多
The effect of microstructure evolution on the tensile properties of 2050 Al-Li alloy thick plate aged at 150 ℃ with 80 mm in thickness(t) was studied from a microstructural perspective. Scanning electron microscope, ...The effect of microstructure evolution on the tensile properties of 2050 Al-Li alloy thick plate aged at 150 ℃ with 80 mm in thickness(t) was studied from a microstructural perspective. Scanning electron microscope, optical microscope, transmission electron microscope and X-ray diffractometer were used to explore the surface(t/6), interlayer(t/3) and center(t/2) thickness layer of this alloy. Results show that the secondary phases on grain boundaries, precipitates and textures vary depending on the thickness location. The precipitation strengthening has a stronger influence on the alloy along the rolling direction than the transverse direction from the under-aged to the peak-aging condition;however, its effect on the anisotropy is insignificant. The higher Taylor factor(M) value caused by stronger β fiber rolling textures and the intergranular phases is the main reason that leads to the highest strength at the t/2 position along the rolling direction. The M-value has a limited change at different thickness layers along the transverse direction, which causes the same tensile strength.展开更多
The microstructures and mechanical properties of Al-3.35Cu-1.2Li-0.4Mg-0.4Zn-0.3Mn-0.1Zr （mass fraction, %） alloywith Sc addition or free Sc were investigated through tensile test, SEM, EPMA and TEM. The addition of...The microstructures and mechanical properties of Al-3.35Cu-1.2Li-0.4Mg-0.4Zn-0.3Mn-0.1Zr （mass fraction, %） alloywith Sc addition or free Sc were investigated through tensile test, SEM, EPMA and TEM. The addition of 0.082% （mass fraction） Scelement leads to the formation of Cu-rich and Sc-contained nano-sized Al3（ScZr） particles and W phase particles. The Al3（ScZr）particles can inhibit recrystallization to a certain extent and impede recrystallized grain growth during solution treatment. It is foundthat W phase cannot dissolve in supersaturated solid solution during the solution heat treatment, and the Cu content in thesolutionized matrix is decreased, which causes a decrease in the fraction of Cu-contained strengthening precipitates with T1 （Al2CuLi）and θ＇ （Al2Cu） under T8 aging condition. Due to the formation of the W phases, the small Sc addition causes a little reduction in thestrength.展开更多
The evolution and distribution of the aging precipitates in 1460 Al-Li alloy with high Li concentration (2.14%, mass fraction) during T6 aging and two-step T8 (4% predeformation) aging were investigated through TEM. T...The evolution and distribution of the aging precipitates in 1460 Al-Li alloy with high Li concentration (2.14%, mass fraction) during T6 aging and two-step T8 (4% predeformation) aging were investigated through TEM. The aging precipitates include δ'(Al3Li) and T1 (Al2CuLi) phases, of which the δ' phases are formed first in grain interiors. A lot of δ'/GPI/δ' composite precipitates in which GPI zones are flanked with a pair of δ' phases, are formed at 145℃ of T6 aging, which are thermally stable. At 160℃ and 175℃ of T6 aging, many T1 phases nucleate first at subgrain boundaries and grain boundaries, and then form and grow within grains. As to the T8 aging, the δ'/GPI/δ' composite precipitates are formed during the first-step aging at 130℃ for 20 h, which are thermally stable during the second-step aging at 160℃. The plastic predeformation accelerates T1 nucleation within grains during the second-step aging at 160℃.展开更多
Hot compression tests of 2050 Al-Li alloy were performed in the deformation temperature range of 340-500°C and strain rate range of 0.001-10 s-1 to investigate the hot deformation behavior of the alloy.The effect...Hot compression tests of 2050 Al-Li alloy were performed in the deformation temperature range of 340-500°C and strain rate range of 0.001-10 s-1 to investigate the hot deformation behavior of the alloy.The effects of friction and temperature difference on flow stress were analyzed and the flow curves were corrected.Based on the dynamic material model,processing map at a strain of 0.5 was established.The grain structure of the compressed samples was observed using optical microscopy.The results show that friction and temperature variation during the hot compression have significant influences on flow stress.The optimum processing domains are in the temperature range from 370 to 430°C with the strain rate range from 0.01 to 0.001 s-1,and in the temperature range from 440 to 500°C with the strain rate range from 0.3 to 0.01 s-1;the flow instable region is located at high strain rates(3-10 s-1)in the entire temperature range.Dynamic recovery(DRV)and dynamic recrystallization(DRX)are the main deformation mechanisms of the 2050 alloy in the stable domains,whereas the alloy exhibits flow localization in the instable region.展开更多
The effect of cold rolling reduction(50%-90%)on the grain structures of solutionized 1445 Al-Li alloy sheet at525-575 ℃ was investigated through electron backscatter diffraction(EBSD).Although the solutionization tem...The effect of cold rolling reduction(50%-90%)on the grain structures of solutionized 1445 Al-Li alloy sheet at525-575 ℃ was investigated through electron backscatter diffraction(EBSD).Although the solutionization temperature is elevated to 575 ℃,the sheet is not completely recrystallized.The main recrystallization model is subgrain coalescence and growth,and the non-recrystallization is due to the formed nano-sized Al3(Sc,Zr)dispersoids,which pin the grain boundaries,subgrain boundaries and dislocations.With increasing the cold rolling reduction,the fraction and size of the recrystallized grains in the sheet solutionized at525 ℃ are decreased,but the fraction of the subgrains is increased,leading to a decrease in the fraction of the deformed structures.Meanwhile,the number fraction of high-angle boundaries(HABs)is increased.Due to the decreased fraction of the deformed structures and increased fraction of the HABs,the T8-aged 1445 Al-Li alloy sheet displays a decrease trend in the strength and heterogeneity with increasing the cold rolling reduction.At higher solutionization temperature of 575 ℃,the fraction of the recrystallized grains and their size are obviously increased.展开更多
Objective： To understand the changing trajectory of quality of life（QOL） during the treatment courses of breast cancer patients during chemotherapy and to investigate the factors in each treatment course that affec...Objective： To understand the changing trajectory of quality of life（QOL） during the treatment courses of breast cancer patients during chemotherapy and to investigate the factors in each treatment course that affect QOL.Methods： The M.D. Anderson Symptom Inventory Scale, the Hospital Anxiety and Depression Scale（HADS）, and the Functional Assessment of Cancer Therapy-Breast（FACT-B） scale were used to perform a survey on 174 breast cancer patients who received the TAC（docetaxel, Adriamycin, and cyclophosphamide） chemotherapy regimen before postoperative chemotherapy and 5-7 days after each chemotherapy course.Results： The QOL scores of the breast cancer patients were the lowest before the postoperative chemotherapy（81.2 ± 19.6） and the highest after the second chemotherapy course（94.5 ± 14.4）. After the fourth and fifth chemotherapy courses, the scores were much lower again, with values of 82.7 ± 13.9and 82.6 ± 13.1, respectively. The scores improved again after the sixth chemotherapy course（93.9 ± 18.7）. Furthermore, each treatment course had different related symptoms that affected the QOL of the patients.Conclusions： More attention should be paid to the changing trajectory of QOL of patients in all treatment courses and to the influence of treatment-related symptoms on the QOL of patients; moreover, interventions should be adopted by medical care personnel to increase QOL in cancer patients.展开更多
Objective：To investigate the status of diagnosis and treatment of primary breast cancer in Beijing,2008.Methods：All the patients who were diagnosed as primary breast cancer in Beijing in 2008 were enrolled in this s...Objective：To investigate the status of diagnosis and treatment of primary breast cancer in Beijing,2008.Methods：All the patients who were diagnosed as primary breast cancer in Beijing in 2008 were enrolled in this study.Information of these patients,including the features of tumors,clinical diagnosis and treatment was collected,and filled in the well-designed questionnaire forms by trained surveyors.The missing data were partly complemented through telephone interviews.Results：A total of 3473 Beijing citizens were diagnosed as primary breast cancer（25 patients with synchronal bilateral breast cancer） in Beijing,2008.Of them 82.09% were symptomatic.19.02% and 34.11% were diagnosed using fine needle aspiration biopsy（FNAB） and core needle biopsy（CNB）,respectively.15.92% received sentinel lymph node biopsy（SLNB） and 24.27% received breast conserving surgery（BCS）.Among 476 cases with Her-2 positive,only 96 received anti-Her-2 therapy.We found that the standardization level varied in hospitals of different grades,with higher level in Grade-III hospitals.Of note,some breast cancer patients received non-standard primary tumor therapy：65.63% of the patients with ductal carcinoma in situ（DCIS） received axillary lymph node dissection and 36.88% received chemotherapy;25.89% of the patients underwent breast conserving surgery without margin status;12.10% of the patients received chemotherapy less than 4 cycles.Conclusion：Although most breast cancer patients received basic medical care,the mode of diagnosis and treatment should be improved and should be standardized in the future in Beijing.展开更多
Objective： To investigate the associations between the different breast cancer subtypes and survival in Chinese women with operable primary breast cancer. Methods： A total of 1538 Chinese women with operable primary...Objective： To investigate the associations between the different breast cancer subtypes and survival in Chinese women with operable primary breast cancer. Methods： A total of 1538 Chinese women with operable primary breast cancer were analyzed in this study, the median follow-up was 77 months. Estrogen receptor （ER）, progesterone receptor （PR）, and HER2 status were available for these patients. Results： Luminal A （ER＋ and/or PR＋, HER2-） had a favorable disease-free survival （DFS） and overall survival （OS） compared with other subtypes in the entire cohort. Using the luminal A as a reference, among the patients with lymph node positive disease, HER2＋ （ER-, PR-, HER2＋） had the worst DFS （hazard ratio, HR=1.80, 95% CI 1.11 to 2.91, P=0.017） and luminal B （ER＋ and/or PR＋, HER2＋） had the worst OS （HR=2.27, 95% CI 1.50 to 3.45, P0.001）; among the patients with lymph node negative disease, triple-negative （ER-, PR-, HER2-） had the worst DFS （HR=2.21, 95% CI 1.43 to 3.41, P0.001）, whereas no significant difference in DFS between HER2＋ and luminal B or luminal A was observed. Conclusion： As compared with luminal A, luminal B and HER2＋ have the worst survival in patients with lymph node positive disease, but this is not the case in patients with lymph node negative disease; triple-negative subtype has a worse survival in both lymph node positive and lymph node negative patients.展开更多
目的探讨沉默信息调节因子1(SIRT1)在异烟肼致人肝细胞损伤中的作用。方法培养人正常肝细胞HL-7702,实验分为6组:空白对照组、异烟肼组、异烟肼+SIRT1激动剂组、SIRT1激动剂对照组、异烟肼+SIRT1抑制剂组、SIRT1抑制剂对照组。取各组细...目的探讨沉默信息调节因子1(SIRT1)在异烟肼致人肝细胞损伤中的作用。方法培养人正常肝细胞HL-7702,实验分为6组:空白对照组、异烟肼组、异烟肼+SIRT1激动剂组、SIRT1激动剂对照组、异烟肼+SIRT1抑制剂组、SIRT1抑制剂对照组。取各组细胞上清液测定丙氨酸转氨酶(ALT)、天门冬氨酸转氨酶(AST)含量;实时荧光定量聚合酶链反应(q RT-PCR)检测肝细胞SIRT1、NF-k B p65 mRNA表达水平;酶联免疫吸附法(ELISA)检测SIRT1、核转录因子k B(NF-k B p65)、白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)蛋白表达水平。结果与空白对照组比较,异烟肼组细胞SIRT1的mRNA和蛋白表达下降(P<0.05),其下游靶基因NF-k B p65的mRNA和蛋白表达升高(P<0.05),炎症因子IL-6、TNF-α蛋白表达水平升高(P<0.05)。加入SIRT1激动剂可减轻异烟肼引起的炎症反应,加入SIRT1抑制剂可使NF-k B p65、IL-6、TNF-α表达水平进一步升高从而加重细胞的炎症损伤。结论异烟肼诱导肝细胞损伤过程中,降低SIRT1水平,增加炎症因子的表达。SIRT1的激活可以通过降低NF-k B p65表达进而减轻肝细胞损伤的发生。展开更多
Objective To investigate the impact of microvascular obstruction(MVO)on the global and regional myocardial function by cardiac magnetic resonance feature-tracking(CMR-FT)in ST-segment-elevation myocardial infarction(S...Objective To investigate the impact of microvascular obstruction(MVO)on the global and regional myocardial function by cardiac magnetic resonance feature-tracking(CMR-FT)in ST-segment-elevation myocardial infarction(STEMI)patients after percutaneous coronary intervention.Methods Consecutive acute STEMI patients who underwent cardiac magnetic resonance imaging 1-7 days after successful reperfusion by percutaneous coronary intervention treatment were included in this retrospective study.Based on the presence or absence of MVO on late gadolinium enhancement images,patients were divided into groups with MVO and without MVO.The infarct zone,adjacent zone,and remote zone were determined based on a myocardial 16-segment model.The radial strain(RS),circumferential strain(CS),and longitudinal strain(LS)of the global left ventricle(LV)and the infarct,adjacent,and remote zones were measured by CMRFT from cine images and compared between patients with and without MVO using independent-samples t-test.Logistic regression analysis was used to assess the association of MVO with the impaired LV function.Results A total of 157 STEMI patients(mean age 56.66±11.38 years)were enrolled.MVO was detected in 37.58%(59/157)of STEMI patients,and the mean size of MVO was 3.00±3.76 mL.Compared with patients without MVO(n=98),the MVO group had significantly reduced LV global RS(t=-4.30,P<0.001),global CS(t=4.99,P<0.001),and global LS(t=3.51,P=0.001).The RS and CS of the infarct zone in patients with MVO were significantly reduced(t=-3.38,P=0.001;t=2.64,P=0.01;respectively)and the infarct size was significantly larger(t=8.37,P<0.001)than that of patients without MVO.The presence of LV MVO[OR=4.10,95%CI:2.05-8.19,P<0.001]and its size[OR=1.38,95%CI:1.10-1.72,P=0.01],along with the heart rate and LV infarct size were significantly associated with impaired LV global CS in univariable Logistic regression analysis,while only heart rate(OR=1.08,95%CI:1.03-1.13,P=0.001)and LV infarct size(OR=1.10,95%CI:1.03-1.16,P=0.003)were independent influencing factors for the impaired LV global CS in multivariable Logistic regression analysis.Conclusion The infarct size was larger in STEMI patients with MVO,and MVO deteriorates the global and regional LV myocardial function.展开更多
CEREBRAL aspergillosis is a rare and severe disorder with rapid progressive pathogenesis,and commonly seen in immunocompromised patients.1Typical cerebral aspergillosis presents abscess with ring enhancement or cortic...CEREBRAL aspergillosis is a rare and severe disorder with rapid progressive pathogenesis,and commonly seen in immunocompromised patients.1Typical cerebral aspergillosis presents abscess with ring enhancement or cortical or subcortical infactions on magnetic resonance(MR)images.In this communication,we describe a rare cerebral aspergillosis with relative characteristic MR imaging findings.展开更多
The influence of pre-deformation on aging precipitates of three near peak-aged Al–Cu–Li alloys,1460 alloy with a low Cu/Li ratio（1.46）,2050 alloy with a high Cu/Li ratio（4.51） and 2A96 alloy with a medium Cu/Li ...The influence of pre-deformation on aging precipitates of three near peak-aged Al–Cu–Li alloys,1460 alloy with a low Cu/Li ratio（1.46）,2050 alloy with a high Cu/Li ratio（4.51） and 2A96 alloy with a medium Cu/Li ratio（2.97）,was investigated.The strength of the aged alloys is enhanced by the pre-deformation.The effectiveness of pre-deformation on precipitates is dependent on the alloy＇s composition.With increasing the pre-deformation,the population density of T1（Al2Cu Li） precipitates increases in all three Al–Cu–Li alloys and their diameter decreases in 2050 and 2A96 alloys,and the greatest effectiveness is observed in 2A96 alloy.The pre-deformation also increases the population density of θ＇（Al2Cu）precipitates and decreases their diameter in 2050 and 2A96 Al–Li alloys,but the effectiveness is smaller compared to that on T1 precipitates.In 1460 alloy subjected to two-step aging at 130 ℃ for 20 h followed by 160 ℃ for 12 h,the main precipitates are δ＇（Al3Li）.At 2%–6% pre-deformation,GP-I zones form and pre-deformation displays little influence.Eight percentage pre-deformation promotes θ＇＇/θ＇ precipitation and increases their population density.展开更多
The microstructure evolution and the corrosion feature of Al–x Cu– y Li–Mg alloys( x : y = 0.44, 1.65 and 4.2) were systematically investigated under the same artificial aging conditions. The relationships between ...The microstructure evolution and the corrosion feature of Al–x Cu– y Li–Mg alloys( x : y = 0.44, 1.65 and 4.2) were systematically investigated under the same artificial aging conditions. The relationships between types of precipitates and mechanical performance, as well as electrochemical behaviors, were discussed. Our results show that different types of precipitates can be obtained in alloys with different Cu/Li mass ratios, which significantly influences the mechanical performance of the alloys and substantial corrosion behaviors. Specifically, the analogous corrosion evolution in the aging Al– x Cu– y Li–Mg alloys was first ascertained to be derived from the growth mechanism of the precipitates at the grain boundary(GB). Moreover, a small number of GB precipitates can be obtained in the aged alloy with the lowest Cu/Li mass ratio, thereby resulting in the largest intergranular corrosion resistance. A higher proportion of the GB T1 phase in the continuous precipitates induces higher corrosion sensitivity in alloy with a high Cu/Li mass ratio.展开更多
The uplift of different parts of the Tibetan Plateau caused by the collision,subduction and thickening of the Indian-Eurasian continent is considered to be the most significant landform change of Asia in the last 50 M...The uplift of different parts of the Tibetan Plateau caused by the collision,subduction and thickening of the Indian-Eurasian continent is considered to be the most significant landform change of Asia in the last 50 Ma.The plateau uplift led to elevation and topographical changes in neighboring areas and created diversified niches for the distribution and migration of plants and animals.The resultant high mountains controlled the South Asian monsoon,preventing the monsoon from crossing the plateau and reaching the hinterland of Asia.展开更多
基金supported by the Natural Science Foundation of Hunan Province, China (No. 2023JJ30678)。
文摘The microstructure evolution and mechanical properties of a T8-aged Al-Cu-Li alloy with increased pre-deformation(0-15%) were investigated,revealing the microstructure-strength relationship and the intrinsic strengthening mechanism.The results show that increasing the pre-deformation levels remarkably improves the strength of the alloy but deteriorates its ductility.Dislocations introduced by pre-deformation effectively suppress the formation of Guinier-Preston(GP) zones and provide more nucleation sites for T1 precipitates.This leads to more intensive and finer T1 precipitates in the samples with higher pre-deformation levels.Simultaneously,the enhanced precipitation of T1 precipitates and inhibited formation of GP zones cause the decreases in number and sizes of θ′ precipitates.The quantitative descriptions of the strength contributions from different strengthening mechanisms reveal that strengthening contributions from T1 and θ′ precipitates decrease with increasing pre-deformation.The reduced diameters of T1 precipitates are primarily responsible for their weakened strengthening effects.Therefore,the improved strength of the T8-aged Al-Cu-Li alloy is mainly attributed to the stronger strain hardening from the increased pre-deformation levels.
基金supported by Shandong Science and Technology Development Plan Project(No.Y2006C02)
文摘Objective: To discuss the expression and significance of angiostatin, vascular endothelial growth factor and matrix metalloproteinase-9 in the brain tissue of diabetic rats with ischemia reperfusion. Methods: A total of 60 male Wistar rats were randomly divided into the normal group, sham group, diabetic cerebral infarction group and single cerebral infarction group according to the random number table, with 15 rats in each group. The high sucrose diet and intraperitoneal injection of streptozotocin were performed for the modeling of diabetic rats, while the thread-occlusion method was employed to build the model of cerebral ischemia reperfusion. The immunohistochemical staining was performed to detect the expression of angiostatin, vascular endothelial growth factor(VEGF) and matrix metalloproteinase-9(MMP-9) in the brain tissue. Results: The expression of angiostatin after the reperfusion in the brain tissue of rats in the single cerebral infarction group and diabetic cerebral infarction group was increased 6 h after the reperfusion, reached to the peak on 1 d and then decreased gradually. The expression of angiostatin in the diabetic cerebral infarction group 6 h, 1 d, 3 d and 7 d after the reperfusion was significantly higher than that in the single cerebral infarction group(P<0.05). VEGF began to be increased 1 h after the reperfusion in the single cerebral infarction group and diabetic cerebral infarction group, reached to the peak at 6 h and then decreased gradually. The expression of VEGF in the diabetic cerebral infarction group at each time point after the reperfusion was significantly lower than that in the single cerebral infarction group(P<0.05). MMP-9 began to be be increased 1 h after the reperfusion in the single cerebral infarction group and diabetic cerebral infarction group, reached to the peak on 1 d and then decreased gradually. The expression of MMP-9 in the diabetic cerebral infarction group at each time point after the reperfusion was significantly higher than that in the single cerebral infarction group(P<0.05). Conclusions: The high glucose environment in which the diabetic cerebral infarction is occurred is to induce the formation of MMP-9 at first and then activate and increase the expression of angiostatin. Afterwards, the expression of VEGF is inhibited, resulting in the poor angiogenesis after cerebral infarction, which thus makes the injury of brain tissue after cerebral infarction even worse than the non-diabetes mellitus.
基金Project(2013AA032401)supported by the National High Technology Research and Development Program of China。
文摘2195 Al-Li alloy was deformed through extrusion followed by cold-rolling.The textures of the extruded plate and cold-rolled sheet after solutionization were investigated.The longitudinal strength and precipitates after T8 aging were measured and observed,respectively.Compared to those in the sheet,T1(Al2 Cu Li)precipitates in the extruded plate after T8 aging are non-uniform,and their incubation time is shorter.The extruded plate after solutionization is not recrystallized and contains 55.28%deformation textures of Brass and S.In the cold-rolled sheet after solutionization,massive recrystallization occurs and S component disappears.Due to the higher fraction of Brass and S textures with higher Schmid factor and lower equivalent sliding system number,the extruded plate possesses an yield strength not higher or even lower,but a tensile strength higher,than the cold-rolled sheet after solutionization.In addition,during the aging after pre-stretch,these textures promote T1 precipitation on preferred sliding planes of cold-rolled sheet and cause its higher yield strength and tensile strength after T8 aging.
基金the National Natural Science Foundation of China(No.51961034)the Key Research and Development Program of Ningxia(No.2018BEB04037),China.
文摘The effect of microstructure evolution on the tensile properties of 2050 Al-Li alloy thick plate aged at 150 ℃ with 80 mm in thickness(t) was studied from a microstructural perspective. Scanning electron microscope, optical microscope, transmission electron microscope and X-ray diffractometer were used to explore the surface(t/6), interlayer(t/3) and center(t/2) thickness layer of this alloy. Results show that the secondary phases on grain boundaries, precipitates and textures vary depending on the thickness location. The precipitation strengthening has a stronger influence on the alloy along the rolling direction than the transverse direction from the under-aged to the peak-aging condition;however, its effect on the anisotropy is insignificant. The higher Taylor factor(M) value caused by stronger β fiber rolling textures and the intergranular phases is the main reason that leads to the highest strength at the t/2 position along the rolling direction. The M-value has a limited change at different thickness layers along the transverse direction, which causes the same tensile strength.
文摘The microstructures and mechanical properties of Al-3.35Cu-1.2Li-0.4Mg-0.4Zn-0.3Mn-0.1Zr （mass fraction, %） alloywith Sc addition or free Sc were investigated through tensile test, SEM, EPMA and TEM. The addition of 0.082% （mass fraction） Scelement leads to the formation of Cu-rich and Sc-contained nano-sized Al3（ScZr） particles and W phase particles. The Al3（ScZr）particles can inhibit recrystallization to a certain extent and impede recrystallized grain growth during solution treatment. It is foundthat W phase cannot dissolve in supersaturated solid solution during the solution heat treatment, and the Cu content in thesolutionized matrix is decreased, which causes a decrease in the fraction of Cu-contained strengthening precipitates with T1 （Al2CuLi）and θ＇ （Al2Cu） under T8 aging condition. Due to the formation of the W phases, the small Sc addition causes a little reduction in thestrength.
基金Projection(2013AA032401)supported by the National High-Tech Research and Development Program of China
文摘The evolution and distribution of the aging precipitates in 1460 Al-Li alloy with high Li concentration (2.14%, mass fraction) during T6 aging and two-step T8 (4% predeformation) aging were investigated through TEM. The aging precipitates include δ'(Al3Li) and T1 (Al2CuLi) phases, of which the δ' phases are formed first in grain interiors. A lot of δ'/GPI/δ' composite precipitates in which GPI zones are flanked with a pair of δ' phases, are formed at 145℃ of T6 aging, which are thermally stable. At 160℃ and 175℃ of T6 aging, many T1 phases nucleate first at subgrain boundaries and grain boundaries, and then form and grow within grains. As to the T8 aging, the δ'/GPI/δ' composite precipitates are formed during the first-step aging at 130℃ for 20 h, which are thermally stable during the second-step aging at 160℃. The plastic predeformation accelerates T1 nucleation within grains during the second-step aging at 160℃.
基金Project(2013JSJJ0001)supported by the Teachers’ Research Fund,Central South University,ChinaProject supported by the Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,China
文摘Hot compression tests of 2050 Al-Li alloy were performed in the deformation temperature range of 340-500°C and strain rate range of 0.001-10 s-1 to investigate the hot deformation behavior of the alloy.The effects of friction and temperature difference on flow stress were analyzed and the flow curves were corrected.Based on the dynamic material model,processing map at a strain of 0.5 was established.The grain structure of the compressed samples was observed using optical microscopy.The results show that friction and temperature variation during the hot compression have significant influences on flow stress.The optimum processing domains are in the temperature range from 370 to 430°C with the strain rate range from 0.01 to 0.001 s-1,and in the temperature range from 440 to 500°C with the strain rate range from 0.3 to 0.01 s-1;the flow instable region is located at high strain rates(3-10 s-1)in the entire temperature range.Dynamic recovery(DRV)and dynamic recrystallization(DRX)are the main deformation mechanisms of the 2050 alloy in the stable domains,whereas the alloy exhibits flow localization in the instable region.
文摘The effect of cold rolling reduction(50%-90%)on the grain structures of solutionized 1445 Al-Li alloy sheet at525-575 ℃ was investigated through electron backscatter diffraction(EBSD).Although the solutionization temperature is elevated to 575 ℃,the sheet is not completely recrystallized.The main recrystallization model is subgrain coalescence and growth,and the non-recrystallization is due to the formed nano-sized Al3(Sc,Zr)dispersoids,which pin the grain boundaries,subgrain boundaries and dislocations.With increasing the cold rolling reduction,the fraction and size of the recrystallized grains in the sheet solutionized at525 ℃ are decreased,but the fraction of the subgrains is increased,leading to a decrease in the fraction of the deformed structures.Meanwhile,the number fraction of high-angle boundaries(HABs)is increased.Due to the decreased fraction of the deformed structures and increased fraction of the HABs,the T8-aged 1445 Al-Li alloy sheet displays a decrease trend in the strength and heterogeneity with increasing the cold rolling reduction.At higher solutionization temperature of 575 ℃,the fraction of the recrystallized grains and their size are obviously increased.
基金supported by a project of scientific research of the Affiliated Hospital of Luzhou Medical College(No.14039)
文摘Objective： To understand the changing trajectory of quality of life（QOL） during the treatment courses of breast cancer patients during chemotherapy and to investigate the factors in each treatment course that affect QOL.Methods： The M.D. Anderson Symptom Inventory Scale, the Hospital Anxiety and Depression Scale（HADS）, and the Functional Assessment of Cancer Therapy-Breast（FACT-B） scale were used to perform a survey on 174 breast cancer patients who received the TAC（docetaxel, Adriamycin, and cyclophosphamide） chemotherapy regimen before postoperative chemotherapy and 5-7 days after each chemotherapy course.Results： The QOL scores of the breast cancer patients were the lowest before the postoperative chemotherapy（81.2 ± 19.6） and the highest after the second chemotherapy course（94.5 ± 14.4）. After the fourth and fifth chemotherapy courses, the scores were much lower again, with values of 82.7 ± 13.9and 82.6 ± 13.1, respectively. The scores improved again after the sixth chemotherapy course（93.9 ± 18.7）. Furthermore, each treatment course had different related symptoms that affected the QOL of the patients.Conclusions： More attention should be paid to the changing trajectory of QOL of patients in all treatment courses and to the influence of treatment-related symptoms on the QOL of patients; moreover, interventions should be adopted by medical care personnel to increase QOL in cancer patients.
基金supported by the grant from Beijing Municipal Science & Technology Commission (No. D09050703650902)
文摘Objective：To investigate the status of diagnosis and treatment of primary breast cancer in Beijing,2008.Methods：All the patients who were diagnosed as primary breast cancer in Beijing in 2008 were enrolled in this study.Information of these patients,including the features of tumors,clinical diagnosis and treatment was collected,and filled in the well-designed questionnaire forms by trained surveyors.The missing data were partly complemented through telephone interviews.Results：A total of 3473 Beijing citizens were diagnosed as primary breast cancer（25 patients with synchronal bilateral breast cancer） in Beijing,2008.Of them 82.09% were symptomatic.19.02% and 34.11% were diagnosed using fine needle aspiration biopsy（FNAB） and core needle biopsy（CNB）,respectively.15.92% received sentinel lymph node biopsy（SLNB） and 24.27% received breast conserving surgery（BCS）.Among 476 cases with Her-2 positive,only 96 received anti-Her-2 therapy.We found that the standardization level varied in hospitals of different grades,with higher level in Grade-III hospitals.Of note,some breast cancer patients received non-standard primary tumor therapy：65.63% of the patients with ductal carcinoma in situ（DCIS） received axillary lymph node dissection and 36.88% received chemotherapy;25.89% of the patients underwent breast conserving surgery without margin status;12.10% of the patients received chemotherapy less than 4 cycles.Conclusion：Although most breast cancer patients received basic medical care,the mode of diagnosis and treatment should be improved and should be standardized in the future in Beijing.
基金supported by grants from the Program fro Breast Cancer Tissue Bank of Beijingthe National Natural Science Foundation of China (No.30973436)
文摘Objective： To investigate the associations between the different breast cancer subtypes and survival in Chinese women with operable primary breast cancer. Methods： A total of 1538 Chinese women with operable primary breast cancer were analyzed in this study, the median follow-up was 77 months. Estrogen receptor （ER）, progesterone receptor （PR）, and HER2 status were available for these patients. Results： Luminal A （ER＋ and/or PR＋, HER2-） had a favorable disease-free survival （DFS） and overall survival （OS） compared with other subtypes in the entire cohort. Using the luminal A as a reference, among the patients with lymph node positive disease, HER2＋ （ER-, PR-, HER2＋） had the worst DFS （hazard ratio, HR=1.80, 95% CI 1.11 to 2.91, P=0.017） and luminal B （ER＋ and/or PR＋, HER2＋） had the worst OS （HR=2.27, 95% CI 1.50 to 3.45, P0.001）; among the patients with lymph node negative disease, triple-negative （ER-, PR-, HER2-） had the worst DFS （HR=2.21, 95% CI 1.43 to 3.41, P0.001）, whereas no significant difference in DFS between HER2＋ and luminal B or luminal A was observed. Conclusion： As compared with luminal A, luminal B and HER2＋ have the worst survival in patients with lymph node positive disease, but this is not the case in patients with lymph node negative disease; triple-negative subtype has a worse survival in both lymph node positive and lymph node negative patients.
文摘目的探讨沉默信息调节因子1(SIRT1)在异烟肼致人肝细胞损伤中的作用。方法培养人正常肝细胞HL-7702,实验分为6组:空白对照组、异烟肼组、异烟肼+SIRT1激动剂组、SIRT1激动剂对照组、异烟肼+SIRT1抑制剂组、SIRT1抑制剂对照组。取各组细胞上清液测定丙氨酸转氨酶(ALT)、天门冬氨酸转氨酶(AST)含量;实时荧光定量聚合酶链反应(q RT-PCR)检测肝细胞SIRT1、NF-k B p65 mRNA表达水平;酶联免疫吸附法(ELISA)检测SIRT1、核转录因子k B(NF-k B p65)、白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)蛋白表达水平。结果与空白对照组比较,异烟肼组细胞SIRT1的mRNA和蛋白表达下降(P<0.05),其下游靶基因NF-k B p65的mRNA和蛋白表达升高(P<0.05),炎症因子IL-6、TNF-α蛋白表达水平升高(P<0.05)。加入SIRT1激动剂可减轻异烟肼引起的炎症反应,加入SIRT1抑制剂可使NF-k B p65、IL-6、TNF-α表达水平进一步升高从而加重细胞的炎症损伤。结论异烟肼诱导肝细胞损伤过程中,降低SIRT1水平,增加炎症因子的表达。SIRT1的激活可以通过降低NF-k B p65表达进而减轻肝细胞损伤的发生。
文摘Objective To investigate the impact of microvascular obstruction(MVO)on the global and regional myocardial function by cardiac magnetic resonance feature-tracking(CMR-FT)in ST-segment-elevation myocardial infarction(STEMI)patients after percutaneous coronary intervention.Methods Consecutive acute STEMI patients who underwent cardiac magnetic resonance imaging 1-7 days after successful reperfusion by percutaneous coronary intervention treatment were included in this retrospective study.Based on the presence or absence of MVO on late gadolinium enhancement images,patients were divided into groups with MVO and without MVO.The infarct zone,adjacent zone,and remote zone were determined based on a myocardial 16-segment model.The radial strain(RS),circumferential strain(CS),and longitudinal strain(LS)of the global left ventricle(LV)and the infarct,adjacent,and remote zones were measured by CMRFT from cine images and compared between patients with and without MVO using independent-samples t-test.Logistic regression analysis was used to assess the association of MVO with the impaired LV function.Results A total of 157 STEMI patients(mean age 56.66±11.38 years)were enrolled.MVO was detected in 37.58%(59/157)of STEMI patients,and the mean size of MVO was 3.00±3.76 mL.Compared with patients without MVO(n=98),the MVO group had significantly reduced LV global RS(t=-4.30,P<0.001),global CS(t=4.99,P<0.001),and global LS(t=3.51,P=0.001).The RS and CS of the infarct zone in patients with MVO were significantly reduced(t=-3.38,P=0.001;t=2.64,P=0.01;respectively)and the infarct size was significantly larger(t=8.37,P<0.001)than that of patients without MVO.The presence of LV MVO[OR=4.10,95%CI:2.05-8.19,P<0.001]and its size[OR=1.38,95%CI:1.10-1.72,P=0.01],along with the heart rate and LV infarct size were significantly associated with impaired LV global CS in univariable Logistic regression analysis,while only heart rate(OR=1.08,95%CI:1.03-1.13,P=0.001)and LV infarct size(OR=1.10,95%CI:1.03-1.16,P=0.003)were independent influencing factors for the impaired LV global CS in multivariable Logistic regression analysis.Conclusion The infarct size was larger in STEMI patients with MVO,and MVO deteriorates the global and regional LV myocardial function.
文摘CEREBRAL aspergillosis is a rare and severe disorder with rapid progressive pathogenesis,and commonly seen in immunocompromised patients.1Typical cerebral aspergillosis presents abscess with ring enhancement or cortical or subcortical infactions on magnetic resonance(MR)images.In this communication,we describe a rare cerebral aspergillosis with relative characteristic MR imaging findings.
基金the National High Technology Research and Development Program of China(No.2013AA032401)Teacher’s Research Foundation of Central South University(No.2013JSJJ 001) for the financial supportNonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Centre
文摘The influence of pre-deformation on aging precipitates of three near peak-aged Al–Cu–Li alloys,1460 alloy with a low Cu/Li ratio（1.46）,2050 alloy with a high Cu/Li ratio（4.51） and 2A96 alloy with a medium Cu/Li ratio（2.97）,was investigated.The strength of the aged alloys is enhanced by the pre-deformation.The effectiveness of pre-deformation on precipitates is dependent on the alloy＇s composition.With increasing the pre-deformation,the population density of T1（Al2Cu Li） precipitates increases in all three Al–Cu–Li alloys and their diameter decreases in 2050 and 2A96 alloys,and the greatest effectiveness is observed in 2A96 alloy.The pre-deformation also increases the population density of θ＇（Al2Cu）precipitates and decreases their diameter in 2050 and 2A96 Al–Li alloys,but the effectiveness is smaller compared to that on T1 precipitates.In 1460 alloy subjected to two-step aging at 130 ℃ for 20 h followed by 160 ℃ for 12 h,the main precipitates are δ＇（Al3Li）.At 2%–6% pre-deformation,GP-I zones form and pre-deformation displays little influence.Eight percentage pre-deformation promotes θ＇＇/θ＇ precipitation and increases their population density.
基金Postdoctoral Research Station of Mechanical Engineering of school of Mechanical and Electrical Engineering of Central South Universityfinancially supported by the National Foundation of China(No.TDZX-17-005-1)。
文摘The microstructure evolution and the corrosion feature of Al–x Cu– y Li–Mg alloys( x : y = 0.44, 1.65 and 4.2) were systematically investigated under the same artificial aging conditions. The relationships between types of precipitates and mechanical performance, as well as electrochemical behaviors, were discussed. Our results show that different types of precipitates can be obtained in alloys with different Cu/Li mass ratios, which significantly influences the mechanical performance of the alloys and substantial corrosion behaviors. Specifically, the analogous corrosion evolution in the aging Al– x Cu– y Li–Mg alloys was first ascertained to be derived from the growth mechanism of the precipitates at the grain boundary(GB). Moreover, a small number of GB precipitates can be obtained in the aged alloy with the lowest Cu/Li mass ratio, thereby resulting in the largest intergranular corrosion resistance. A higher proportion of the GB T1 phase in the continuous precipitates induces higher corrosion sensitivity in alloy with a high Cu/Li mass ratio.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB26000000)the China National Key Basic Research Program(2014CB954201)+2 种基金the National Natural Science Foundation of China(31570223,32000174)the State Key Laboratory of Systematic and Evolutionary Botany(LSEB2019-1,LSEB2019-4)the Chinese Academy of Sciences President’s International Fellowship Initiative(2018VBA0016)。
文摘The uplift of different parts of the Tibetan Plateau caused by the collision,subduction and thickening of the Indian-Eurasian continent is considered to be the most significant landform change of Asia in the last 50 Ma.The plateau uplift led to elevation and topographical changes in neighboring areas and created diversified niches for the distribution and migration of plants and animals.The resultant high mountains controlled the South Asian monsoon,preventing the monsoon from crossing the plateau and reaching the hinterland of Asia.
