The aim of the present work is to develop a model for simulating double-peak precipitation hardening kinetics in Al-Zn-Mg alloy with the simultaneous formation of different types of precipitates at elevated temperatur...The aim of the present work is to develop a model for simulating double-peak precipitation hardening kinetics in Al-Zn-Mg alloy with the simultaneous formation of different types of precipitates at elevated temperatures based on the modified Langer-Schwartz approach. The double aging peaks are present in the long time age-hardening curves of Al-Zn-Mg alloys. The physically-based model, while taking explicitly into account nucleation, growth, coarsening of the new phase precipitations and two strengthening mechanisms associated with particle-dislocation interaction （shearing and bypassing）, was used for the analysis of precipitates evolution and precipitation hardening during aging of Al-Zn-Mg alloy. Model predictions were compared with the measurements of Al-Zn-Mg alloy. The systematic and quantitative results show that the predicted hardness profiles of double peaks via adding a shape dependent parameter in the growth equation for growth and coarsening generally agree well with the measured ones. Two strengthening mechanisms associated with particle-dislocation interaction （shearing and bypassing） were considered operating simultaneously in view of the particle size-distribution. The transition from shearing to bypassing strengthening mechanism was found to occur at rather early stage of the particle growth. The bypassing was found to be the prevailing strengthening mechanism in the investigated alloys.展开更多
The influence of combination of different designated precipitation hardening and cold working on the tensile properties of 6061 aluminum alloy was investigated. The results indicate that applying single aging at 180 ...The influence of combination of different designated precipitation hardening and cold working on the tensile properties of 6061 aluminum alloy was investigated. The results indicate that applying single aging at 180 ℃ for 4 h in different thermal-mechanical treatments improves both the strength and elongation. However, double aging does not improve the mechanical properties. In addition, pre-aging shows a negative effect on the subsequent precipitation hardening of material. The changes in mechanical properties were discussed by explanation of microstructural evolution due to the competition of precipitation hardening, strain hardening and work softening processes.展开更多
AIM: To investigate whether vascular endothelial growth factor (VEGF) was over-expressed in hepatocellular carcinoma (HCC) or in surrounding cirrhotic liver tissues.METHODS: Immunohistochemistry was performed to inves...AIM: To investigate whether vascular endothelial growth factor (VEGF) was over-expressed in hepatocellular carcinoma (HCC) or in surrounding cirrhotic liver tissues.METHODS: Immunohistochemistry was performed to investigate the expression of VEGF proteins in HCC tissues from 105 consecutive patients undergoing curative resection for HCC. The immunostaining results and related clinicopathologic materials were analyzed with statistical methods. Kaplan-Meier method was used to calculate survival curves, and Log-rank test was performed to compare differences in survival rates of the patients with positive HCC staining and negative VEGF.RESULTS: VEGF-positive expression was found in 72 of105 HCC patients (68.6%). Capsular infiltration (P= 0.005),vascular invasion (P = 0.035) and intrahepatic metastasis(P=0.008) were observed more frequently in patients with VEGF-positive expression than in those with VEGFnegative expression. Kaplan-Meier curves showed that VEGF-positive expression was associated with a shorter overall survival (P = 0.014). VEGF-positive expression was found in 47 of tissues 68 HCC (69.1%), and VEGF-positive expression was found in 54 of 68 surrounding cirrhotic liver tissues (79.4%). VEGF-positive expression was significantly higher in surrounding cirrhotic liver tissues than in HCC (P= 0.017).CONCLUSION: VEGF may play an important role in the angiogenesis and prognosis of HCC, as well as in the angiogenesis of liver cirrhosis.展开更多
AIM:To investigate the efficacy and toxicity of systemic chemotherapy in a retrospective study of patients with hepatocellular carcinoma(HCC)occurring in normal or fibrotic liver without cirrhosis. METHODS:Twenty-four...AIM:To investigate the efficacy and toxicity of systemic chemotherapy in a retrospective study of patients with hepatocellular carcinoma(HCC)occurring in normal or fibrotic liver without cirrhosis. METHODS:Twenty-four patients with metastatic or locally advanced HCC in a normal or a fibrotic liver were given systemic chemotherapy(epirubicin,cis- platin and 5-fluorouracil or epirubicin,cisplatin and capecitabine regimens).Tumor response,time to pro- gression,survival,and toxicity were evaluated. RESULTS:There were 7 women and 17 men,mean age 54±10 years;18 patients had a normal liver and 6 had a fibrotic liver(F1/F2 on biopsy).Mean tumor size was 14 cm,5 patients had portal vein thrombosis and 7 had metastasis.Patients received a median of 4 chemotherapy sessions.Overall tolerance was good. There were 5 partial responses(objective response rate =22%),and tumor control rate was 52%.Second line surgical resection was possible in two patients.Median survival was 11 mo,and 1-and 2-year overall survival rates were 50%±10%and 32%±11%,respectively. CONCLUSION:In patients with HCC in a non-cirrhotic liver,chemotherapy was well tolerated and associated with an objective response rate of 22%,including two patients who underwent secondary surgical resection.展开更多
We report a case of pseudocirrhosis arising in the setting of regression of liver metastases from pancreatic cancer. A 55-year-old asymptomatic woman presented to our clinic with newly diagnosed metastatic pancreatic ...We report a case of pseudocirrhosis arising in the setting of regression of liver metastases from pancreatic cancer. A 55-year-old asymptomatic woman presented to our clinic with newly diagnosed metastatic pancreatic cancer with extensive liver metastases. She underwent systemic chemotherapy with gemcitabine and oxaliplatin (GEMOX). After 8 cycles of therapy, she had a remarkable response to the therapy evidenced by decline of carcinoembryonic antigen (CEA) and CA19 by > 50% and nearly complete resolution of hepatic metastases in computed tomography (CT) scan. Shortly after, she developed increasing bilateral ankle edema and ascites, associated with dyspnea, progressive weight gain, and declining performance status. Gemcitabine and oxaliplatin were discontinued as other causes of her symptoms such as congestive heart disease or venous thrombosis were ruled out. CT scan 6 mo after the initiation of GEMOX revealed worsening ascites with a stable pancreatic mass. However, it also revealed a lobular hepatic contour, segmental atrophy, and capsular retraction mimicking the appearance of cirrhosis. She was managed with aggressive diuresis and albumin infusions which eventually resulted in a resolution of the above- mentioned symptoms as well as complete resolution of pseudocirrhotic appearance of the liver and ascites in CT scan. This case demonstrates that pancreatic cancer patients can develop pseudocirrhosis. Clinicians and radiologist should be well aware of this entity asearly recognition and management can lead to a near complete recovery of liver function and much improved quality of life as illustrated in this case.展开更多
AIM:Cardiovascular autonomic and peripheral sensoryneuropathy is a known complication of chronic alcoholicand non-alcoholic liver diseases.We aimed to assess theprevalence and risk factors for peripheral sensory nerve...AIM:Cardiovascular autonomic and peripheral sensoryneuropathy is a known complication of chronic alcoholicand non-alcoholic liver diseases.We aimed to assess theprevalence and risk factors for peripheral sensory nerveand autonomic dysfunction using sensitive methods inpatients with primary biliary cirrhosis (PBC).METHODS:Twenty-four AMA M2 positive female patientswith clinical,biochemical and histological evidence of PBCand 20 age matched healthy female subjects were studied.Five standard cardiovascular reflex tests and 2d-h heartrate variability(HRV)analysis were performed to defineautonomic function.Peripheral sensory nerve function onmedian and peroneal nerves was characterized by currentperception threshold(CPT),measured by a neuroselectivediagnostic stimulator(Neurotron,Baltimore,MD).RESULTS:Fourteen of 24 patients(58%)had at least oneabnormal cardiovascular reflex test and thirteen(54%)had peripheral sensory neuropathy.Lower heart rateresponse to deep breathing(P=0.001),standing(P=0.03)and Valsalva manoeuvre(P=0.01),and more profounddecrease of blood pressure after standing(P=0.03)wasfound in PBC patients than in controls.As a novel findingwe proved that both time domain and frequency domainparameters of 24-h HRV were significantly reduced in PBCpatients compared to controls.Each patient had at leastone abnormal parameter of HRV.Lower CPT values indicatedhyperaesthesia as a characteristic feature at peronealnerve testing at three frequencies(2000 Hz:P=0.005;250 Hz:P=0.002;5 Hz:P=0.004)in PBC compared tocontrols.Correlation of autonomic dysfunction with theseverity and duration of the disease was observed.Lowertotal power of HRV correlated with lower CPT values atmedian nerve testing at 250 Hz(P=0.0001)and at 5 Hz(P=0.002),as well as with those at peroneal nerve testingat 2000 Hz(P=0.01).CONCLUSION:Autonomic and sensory nerve dysfunctionsare frequent in PBC.Twenty-four-hour HRV analysis is moresensitive than standard cardiovascular tests for detectingof both parasympathetic and sympathetic impairments.Ournovel data suggest that hyperaesthesia is a characteristicfeature of peripheral sensory neuropathy and mightcontribute to itching in PBC.Autonomic dysfunction is relatedto the duration and severity of PBC.展开更多
Zr was added to Ti−Nb−Fe alloys to develop low elastic modulus and high strengthβ-Ti alloys for biomedical applications.Ingots of Ti−12Nb−2Fe−(2,4,6,8,10)Zr(at.%)were prepared by arc melting and then subjected to hom...Zr was added to Ti−Nb−Fe alloys to develop low elastic modulus and high strengthβ-Ti alloys for biomedical applications.Ingots of Ti−12Nb−2Fe−(2,4,6,8,10)Zr(at.%)were prepared by arc melting and then subjected to homogenization,cold rolling,and solution treatments.The phases and microstructures of the alloys were analyzed by optical microscopy,X-ray diffraction,and transmission electron microscopy.The mechanical properties were measured by tensile tests.The results indicate that Zr and Fe cause a remarkable solid-solution strengthening effect on the alloys;thus,all the alloys show yield and ultimate tensile strengths higher than 510 MPa and 730 MPa,respectively.Zr plays a weak role in the deformation mechanism.Further,twinning occurs in all the deformed alloys and is beneficial to both strength and plasticity.Ti−12Nb−2Fe−(8,10)Zr alloys with metastableβphases show low elastic modulus,high tensile strength,and good plasticity and are suitable candidate materials for biomedical implants.展开更多
This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and co...This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.展开更多
基金Project(51021063)supported by the Creative Research Group of the National Natural Science Foundation of ChinaProject(50831007)supported by the National Natural Science Foundation of China+1 种基金Project(2011CB610401)supported by the National Basic Research Program of ChinaProject(12C1142)supported by the Education Department of Hunan Province,China
文摘The aim of the present work is to develop a model for simulating double-peak precipitation hardening kinetics in Al-Zn-Mg alloy with the simultaneous formation of different types of precipitates at elevated temperatures based on the modified Langer-Schwartz approach. The double aging peaks are present in the long time age-hardening curves of Al-Zn-Mg alloys. The physically-based model, while taking explicitly into account nucleation, growth, coarsening of the new phase precipitations and two strengthening mechanisms associated with particle-dislocation interaction （shearing and bypassing）, was used for the analysis of precipitates evolution and precipitation hardening during aging of Al-Zn-Mg alloy. Model predictions were compared with the measurements of Al-Zn-Mg alloy. The systematic and quantitative results show that the predicted hardness profiles of double peaks via adding a shape dependent parameter in the growth equation for growth and coarsening generally agree well with the measured ones. Two strengthening mechanisms associated with particle-dislocation interaction （shearing and bypassing） were considered operating simultaneously in view of the particle size-distribution. The transition from shearing to bypassing strengthening mechanism was found to occur at rather early stage of the particle growth. The bypassing was found to be the prevailing strengthening mechanism in the investigated alloys.
基金financial support of Islamic Azad University, Dezful Branch for the project No. 6230
文摘The influence of combination of different designated precipitation hardening and cold working on the tensile properties of 6061 aluminum alloy was investigated. The results indicate that applying single aging at 180 ℃ for 4 h in different thermal-mechanical treatments improves both the strength and elongation. However, double aging does not improve the mechanical properties. In addition, pre-aging shows a negative effect on the subsequent precipitation hardening of material. The changes in mechanical properties were discussed by explanation of microstructural evolution due to the competition of precipitation hardening, strain hardening and work softening processes.
基金Supported by the China Scholarship Council, No. 98915009
文摘AIM: To investigate whether vascular endothelial growth factor (VEGF) was over-expressed in hepatocellular carcinoma (HCC) or in surrounding cirrhotic liver tissues.METHODS: Immunohistochemistry was performed to investigate the expression of VEGF proteins in HCC tissues from 105 consecutive patients undergoing curative resection for HCC. The immunostaining results and related clinicopathologic materials were analyzed with statistical methods. Kaplan-Meier method was used to calculate survival curves, and Log-rank test was performed to compare differences in survival rates of the patients with positive HCC staining and negative VEGF.RESULTS: VEGF-positive expression was found in 72 of105 HCC patients (68.6%). Capsular infiltration (P= 0.005),vascular invasion (P = 0.035) and intrahepatic metastasis(P=0.008) were observed more frequently in patients with VEGF-positive expression than in those with VEGFnegative expression. Kaplan-Meier curves showed that VEGF-positive expression was associated with a shorter overall survival (P = 0.014). VEGF-positive expression was found in 47 of tissues 68 HCC (69.1%), and VEGF-positive expression was found in 54 of 68 surrounding cirrhotic liver tissues (79.4%). VEGF-positive expression was significantly higher in surrounding cirrhotic liver tissues than in HCC (P= 0.017).CONCLUSION: VEGF may play an important role in the angiogenesis and prognosis of HCC, as well as in the angiogenesis of liver cirrhosis.
文摘AIM:To investigate the efficacy and toxicity of systemic chemotherapy in a retrospective study of patients with hepatocellular carcinoma(HCC)occurring in normal or fibrotic liver without cirrhosis. METHODS:Twenty-four patients with metastatic or locally advanced HCC in a normal or a fibrotic liver were given systemic chemotherapy(epirubicin,cis- platin and 5-fluorouracil or epirubicin,cisplatin and capecitabine regimens).Tumor response,time to pro- gression,survival,and toxicity were evaluated. RESULTS:There were 7 women and 17 men,mean age 54±10 years;18 patients had a normal liver and 6 had a fibrotic liver(F1/F2 on biopsy).Mean tumor size was 14 cm,5 patients had portal vein thrombosis and 7 had metastasis.Patients received a median of 4 chemotherapy sessions.Overall tolerance was good. There were 5 partial responses(objective response rate =22%),and tumor control rate was 52%.Second line surgical resection was possible in two patients.Median survival was 11 mo,and 1-and 2-year overall survival rates were 50%±10%and 32%±11%,respectively. CONCLUSION:In patients with HCC in a non-cirrhotic liver,chemotherapy was well tolerated and associated with an objective response rate of 22%,including two patients who underwent secondary surgical resection.
文摘We report a case of pseudocirrhosis arising in the setting of regression of liver metastases from pancreatic cancer. A 55-year-old asymptomatic woman presented to our clinic with newly diagnosed metastatic pancreatic cancer with extensive liver metastases. She underwent systemic chemotherapy with gemcitabine and oxaliplatin (GEMOX). After 8 cycles of therapy, she had a remarkable response to the therapy evidenced by decline of carcinoembryonic antigen (CEA) and CA19 by > 50% and nearly complete resolution of hepatic metastases in computed tomography (CT) scan. Shortly after, she developed increasing bilateral ankle edema and ascites, associated with dyspnea, progressive weight gain, and declining performance status. Gemcitabine and oxaliplatin were discontinued as other causes of her symptoms such as congestive heart disease or venous thrombosis were ruled out. CT scan 6 mo after the initiation of GEMOX revealed worsening ascites with a stable pancreatic mass. However, it also revealed a lobular hepatic contour, segmental atrophy, and capsular retraction mimicking the appearance of cirrhosis. She was managed with aggressive diuresis and albumin infusions which eventually resulted in a resolution of the above- mentioned symptoms as well as complete resolution of pseudocirrhotic appearance of the liver and ascites in CT scan. This case demonstrates that pancreatic cancer patients can develop pseudocirrhosis. Clinicians and radiologist should be well aware of this entity asearly recognition and management can lead to a near complete recovery of liver function and much improved quality of life as illustrated in this case.
文摘AIM:Cardiovascular autonomic and peripheral sensoryneuropathy is a known complication of chronic alcoholicand non-alcoholic liver diseases.We aimed to assess theprevalence and risk factors for peripheral sensory nerveand autonomic dysfunction using sensitive methods inpatients with primary biliary cirrhosis (PBC).METHODS:Twenty-four AMA M2 positive female patientswith clinical,biochemical and histological evidence of PBCand 20 age matched healthy female subjects were studied.Five standard cardiovascular reflex tests and 2d-h heartrate variability(HRV)analysis were performed to defineautonomic function.Peripheral sensory nerve function onmedian and peroneal nerves was characterized by currentperception threshold(CPT),measured by a neuroselectivediagnostic stimulator(Neurotron,Baltimore,MD).RESULTS:Fourteen of 24 patients(58%)had at least oneabnormal cardiovascular reflex test and thirteen(54%)had peripheral sensory neuropathy.Lower heart rateresponse to deep breathing(P=0.001),standing(P=0.03)and Valsalva manoeuvre(P=0.01),and more profounddecrease of blood pressure after standing(P=0.03)wasfound in PBC patients than in controls.As a novel findingwe proved that both time domain and frequency domainparameters of 24-h HRV were significantly reduced in PBCpatients compared to controls.Each patient had at leastone abnormal parameter of HRV.Lower CPT values indicatedhyperaesthesia as a characteristic feature at peronealnerve testing at three frequencies(2000 Hz:P=0.005;250 Hz:P=0.002;5 Hz:P=0.004)in PBC compared tocontrols.Correlation of autonomic dysfunction with theseverity and duration of the disease was observed.Lowertotal power of HRV correlated with lower CPT values atmedian nerve testing at 250 Hz(P=0.0001)and at 5 Hz(P=0.002),as well as with those at peroneal nerve testingat 2000 Hz(P=0.01).CONCLUSION:Autonomic and sensory nerve dysfunctionsare frequent in PBC.Twenty-four-hour HRV analysis is moresensitive than standard cardiovascular tests for detectingof both parasympathetic and sympathetic impairments.Ournovel data suggest that hyperaesthesia is a characteristicfeature of peripheral sensory neuropathy and mightcontribute to itching in PBC.Autonomic dysfunction is relatedto the duration and severity of PBC.
基金the Natural Science Foundation of Shanghai,China(No.15ZR1428400)Shanghai Engineering Research Center of High-Performance Medical Device Materials,China(No.20DZ2255500)the Project of Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development,Tohoku University,sponsored by Ministry,Education,Culture,Sports,Science and Technology,Japan,and the Grant-in Aid for Scientific Research(C)(No.20K05139)from JSPS(Japan Society for the Promotion of Science),Tokyo,Japan.
文摘Zr was added to Ti−Nb−Fe alloys to develop low elastic modulus and high strengthβ-Ti alloys for biomedical applications.Ingots of Ti−12Nb−2Fe−(2,4,6,8,10)Zr(at.%)were prepared by arc melting and then subjected to homogenization,cold rolling,and solution treatments.The phases and microstructures of the alloys were analyzed by optical microscopy,X-ray diffraction,and transmission electron microscopy.The mechanical properties were measured by tensile tests.The results indicate that Zr and Fe cause a remarkable solid-solution strengthening effect on the alloys;thus,all the alloys show yield and ultimate tensile strengths higher than 510 MPa and 730 MPa,respectively.Zr plays a weak role in the deformation mechanism.Further,twinning occurs in all the deformed alloys and is beneficial to both strength and plasticity.Ti−12Nb−2Fe−(8,10)Zr alloys with metastableβphases show low elastic modulus,high tensile strength,and good plasticity and are suitable candidate materials for biomedical implants.
文摘This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.
