The interfacial structure and its effect on the resistivity of cross-layered silver-copper composite strip fabricated by hot-roll bonding and diffusion welding processes with the same specification were studied.Throug...The interfacial structure and its effect on the resistivity of cross-layered silver-copper composite strip fabricated by hot-roll bonding and diffusion welding processes with the same specification were studied.Through optical and scanning electron microscope analysis of metallographic structure of the diffusion region of interface,it is found that the thickness of the interfacial diffusion layer is related to the composite conditions.Under the condition of sufficient diffusion,the interface of silver-copper composite strip produced by diffusion welding process has a wider interfacial transition region and fine grain area.Due to the higher diffusion rate of copper atoms than that of silver atoms,copper atoms tend to aggregate at the silver boundaries to form a copper-rich second solid solution,which has a fixing and expanding effect during annealing.The fine grain area at the interface of the composite strip produced by diffusion welding process still exists after annealing treatment and reaches a width of 55-97μm.While the fine grain region at the interface of hot-rolled composite strips is mainly formed by crushing the surface under rolling pressure with less diffusion effect,it almost disappears after annealing.The resistivity of silver-copper composite strip increases with the extension of the interfacial diffusion region.The resistivity of hot-roll bonding composite strip is increased by about 4%higher than that of the theoretical calculation,while the resistivity of diffusion welding composite strip is increased by 6%.展开更多
AIM:To compare the efficacy of modified percutaneous transhepatic variceal embolization(PTVE)with 2-octyl-cyanoacrylate(2-OCA)and endoscopic variceal obturation(EVO)with an injection of 2-OCA for prophylaxis of gastri...AIM:To compare the efficacy of modified percutaneous transhepatic variceal embolization(PTVE)with 2-octyl-cyanoacrylate(2-OCA)and endoscopic variceal obturation(EVO)with an injection of 2-OCA for prophylaxis of gastric variceal rebleeding. METHODS:In this retrospective study,the medical records of liver cirrhosis patients with gastric variceal bleeding who underwent either endoscopic 2-OCA(EVO) or modified PTVE using 2-OCA at Shandong Provincial Hospital from January 2006 to December 2008 were reviewed.Patient demographics,rebleeding rate,survival rate,and complications were compared between the two groups(PTVE and EVO).All results were expressed as mean±SD,or as a percentage.Quantitative variables were compared by two sample Student t tests, and qualitative variables were compared by the Fisher exact test or theχ 2 test(with Yates correction)where appropriate.A P value less than 0.05 was considered significant.Statistical computation was performed using SPSS 13.0 software. RESULTS:A total of 77 patients were included;45 patients who underwent EVO and 32 patients who received PTVE.During the follow-up(19.78±7.70 mo in the EVO group,vs 21.53±8.56 mo in the PTVE group) rebleeding occurred in 17 patients in the EVO group and in 4 patients in the PTVE group(37.78%vs 12.5%, P=0.028).The cumulative rebleeding-free rate was 75%,59%,and 49%in 1,2,and 3 years respectively for EVO,and 93%,84%,and 84%for PTVE(P=0.011). Cox analysis was used to identify independent factors that predicted rebleeding after treatment.Variables including age,gender,cause,Child-Pugh classification, size of gastric varices(GV),location of GV,and treatment methods were analyzed.It was revealed that Child-Pugh classification[risk ratio(RR)2.10,95%CI:1.03-4.28,P=0.040],choice of treatment(RR 0.25, 95%CI:0.08-0.80,P=0.019),and size of GV(RR 2.14, 95%CI:1.07-4.28,P=0.032)were the independent factors for predicting rebleeding.Follow-up computed tomography revealed that cyanoacrylate was retained in the varices and in the feeding veins of PTVE patients. During the follow-up,eight patients in the EVO group and four patients in the PTVE group died.The cumulative survival rates at 1,2,and 3 years were 93%,84%, and 67%respectively in the EVO group,and 97%, 88%,and 74%respectively in the PTVE group.The survival rates were not significantly different between the two groups(P=0.432).Cox analysis showed that the Child-Pugh classification was the most significant prognostic factor of survival(RR 2.77,95%CI:1.12-6.80,P=0.027).The incidence of complications was similar in both groups. CONCLUSION:With extensive and permanent obliteration of gastric varices and its feeding veins,PTVE with 2-OCA is superior to endoscopic 2-OCA injection for preventing gastric variceal rebleeding.展开更多
Developing high-performance electromagnetic absorbing materials remains a challenge.In this work,Gd-Co ferrite@carbon core-shell structure composites were synthesized by a two-step hydrothermal method.The effects of r...Developing high-performance electromagnetic absorbing materials remains a challenge.In this work,Gd-Co ferrite@carbon core-shell structure composites were synthesized by a two-step hydrothermal method.The effects of rare earth Gd doping amount on the microstructure and electromagnetic wave absorption properties of cobalt ferrite@carbon composites were mainly studied.The results show that an appropriate amount of Gd doping can refine the crystal grain size of cobalt ferrite@carbon composites.However,when the doping amount of Gd exceeds the solid solubility threshold,the secondary phase GdFeO_(3)will be generated and the grain size will increase.When the doping amount of Gd is x=0.04,the reflection loss(RL) of the CoFe_(1.96)Gd_(0.04)O_(4)@C composites reaches the minimum value of -9.26 dB at the absorption layer thickness of 2.0 mm and a frequency of 13.67 GHz,and the effective absorption band(EAB) is 5.01 GHz(10.95-15.96 GHz).Compared with the CoFe_(2)O_(4)@C composites,the RL of the CoFe_(1.96)Gd_(0.04)O_(4)@C composites is increased by 79.35%,and the EAB is broadened by 3.51%.Gd ions enhance the dielectric loss through the grain size effect,and the increase of magnetocrystalline anisotropy enhances the magnetic loss.The CoFe_(1.96)Gd_(0.04)O_(4)@C composites have excellent impedance matching,which relies on the strong magnetic loss of ferrite,the interface polarization,and dipole polarization formed by the carbon shell to attenuate electromagnetic waves.展开更多
The drive toward miniaturization,functionalization,and environmental conservation in electronic devices has increased the demand for low-temperature solder in 3D packaging processes.The influence of Sb incorporation o...The drive toward miniaturization,functionalization,and environmental conservation in electronic devices has increased the demand for low-temperature solder in 3D packaging processes.The influence of Sb incorporation on the structure and properties of SnBiIn solder at an equal molar ratio is investigated.It is demonstrated that Sb incorporation facilitates the formation of SnIn phase and induces the precipitation of spherical Bi particles.Furthermore,the concentration of Sb directly affects the morphologies of both Bi and SbIn phases.The amount of Sb also directly impacts the morphologies of Bi and SbIn phases,resulting in distinct solid solution and second-phase strengthening effects.These effects consequently alter the properties of the solder.This phenomenon arises because Sb hinders atomic diffusion within the joint,leading to the formation of thin Cu_(6)(Sn,In)_(5) intermetallic compounds.It can be reasonably inferred that lead-free low-temperature solders,based on high-entropy alloy multicomponent compositions and engineered via elemental modulation,show promise for successful applications in electronic packaging.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2017YFB0305701)Henan Provincial Science and Technology Research Project(Grant No.182102210138)Science and Technology Openness and Cooperation Projects of Henan Province(Grant No.162106000002).
文摘The interfacial structure and its effect on the resistivity of cross-layered silver-copper composite strip fabricated by hot-roll bonding and diffusion welding processes with the same specification were studied.Through optical and scanning electron microscope analysis of metallographic structure of the diffusion region of interface,it is found that the thickness of the interfacial diffusion layer is related to the composite conditions.Under the condition of sufficient diffusion,the interface of silver-copper composite strip produced by diffusion welding process has a wider interfacial transition region and fine grain area.Due to the higher diffusion rate of copper atoms than that of silver atoms,copper atoms tend to aggregate at the silver boundaries to form a copper-rich second solid solution,which has a fixing and expanding effect during annealing.The fine grain area at the interface of the composite strip produced by diffusion welding process still exists after annealing treatment and reaches a width of 55-97μm.While the fine grain region at the interface of hot-rolled composite strips is mainly formed by crushing the surface under rolling pressure with less diffusion effect,it almost disappears after annealing.The resistivity of silver-copper composite strip increases with the extension of the interfacial diffusion region.The resistivity of hot-roll bonding composite strip is increased by about 4%higher than that of the theoretical calculation,while the resistivity of diffusion welding composite strip is increased by 6%.
文摘AIM:To compare the efficacy of modified percutaneous transhepatic variceal embolization(PTVE)with 2-octyl-cyanoacrylate(2-OCA)and endoscopic variceal obturation(EVO)with an injection of 2-OCA for prophylaxis of gastric variceal rebleeding. METHODS:In this retrospective study,the medical records of liver cirrhosis patients with gastric variceal bleeding who underwent either endoscopic 2-OCA(EVO) or modified PTVE using 2-OCA at Shandong Provincial Hospital from January 2006 to December 2008 were reviewed.Patient demographics,rebleeding rate,survival rate,and complications were compared between the two groups(PTVE and EVO).All results were expressed as mean±SD,or as a percentage.Quantitative variables were compared by two sample Student t tests, and qualitative variables were compared by the Fisher exact test or theχ 2 test(with Yates correction)where appropriate.A P value less than 0.05 was considered significant.Statistical computation was performed using SPSS 13.0 software. RESULTS:A total of 77 patients were included;45 patients who underwent EVO and 32 patients who received PTVE.During the follow-up(19.78±7.70 mo in the EVO group,vs 21.53±8.56 mo in the PTVE group) rebleeding occurred in 17 patients in the EVO group and in 4 patients in the PTVE group(37.78%vs 12.5%, P=0.028).The cumulative rebleeding-free rate was 75%,59%,and 49%in 1,2,and 3 years respectively for EVO,and 93%,84%,and 84%for PTVE(P=0.011). Cox analysis was used to identify independent factors that predicted rebleeding after treatment.Variables including age,gender,cause,Child-Pugh classification, size of gastric varices(GV),location of GV,and treatment methods were analyzed.It was revealed that Child-Pugh classification[risk ratio(RR)2.10,95%CI:1.03-4.28,P=0.040],choice of treatment(RR 0.25, 95%CI:0.08-0.80,P=0.019),and size of GV(RR 2.14, 95%CI:1.07-4.28,P=0.032)were the independent factors for predicting rebleeding.Follow-up computed tomography revealed that cyanoacrylate was retained in the varices and in the feeding veins of PTVE patients. During the follow-up,eight patients in the EVO group and four patients in the PTVE group died.The cumulative survival rates at 1,2,and 3 years were 93%,84%, and 67%respectively in the EVO group,and 97%, 88%,and 74%respectively in the PTVE group.The survival rates were not significantly different between the two groups(P=0.432).Cox analysis showed that the Child-Pugh classification was the most significant prognostic factor of survival(RR 2.77,95%CI:1.12-6.80,P=0.027).The incidence of complications was similar in both groups. CONCLUSION:With extensive and permanent obliteration of gastric varices and its feeding veins,PTVE with 2-OCA is superior to endoscopic 2-OCA injection for preventing gastric variceal rebleeding.
基金financially supported by the National Natural Science Foundation of China (No.51372108)。
文摘Developing high-performance electromagnetic absorbing materials remains a challenge.In this work,Gd-Co ferrite@carbon core-shell structure composites were synthesized by a two-step hydrothermal method.The effects of rare earth Gd doping amount on the microstructure and electromagnetic wave absorption properties of cobalt ferrite@carbon composites were mainly studied.The results show that an appropriate amount of Gd doping can refine the crystal grain size of cobalt ferrite@carbon composites.However,when the doping amount of Gd exceeds the solid solubility threshold,the secondary phase GdFeO_(3)will be generated and the grain size will increase.When the doping amount of Gd is x=0.04,the reflection loss(RL) of the CoFe_(1.96)Gd_(0.04)O_(4)@C composites reaches the minimum value of -9.26 dB at the absorption layer thickness of 2.0 mm and a frequency of 13.67 GHz,and the effective absorption band(EAB) is 5.01 GHz(10.95-15.96 GHz).Compared with the CoFe_(2)O_(4)@C composites,the RL of the CoFe_(1.96)Gd_(0.04)O_(4)@C composites is increased by 79.35%,and the EAB is broadened by 3.51%.Gd ions enhance the dielectric loss through the grain size effect,and the increase of magnetocrystalline anisotropy enhances the magnetic loss.The CoFe_(1.96)Gd_(0.04)O_(4)@C composites have excellent impedance matching,which relies on the strong magnetic loss of ferrite,the interface polarization,and dipole polarization formed by the carbon shell to attenuate electromagnetic waves.
基金financially supported by the Key Research and Development Projects in Henan Province,China(231111231500).
文摘The drive toward miniaturization,functionalization,and environmental conservation in electronic devices has increased the demand for low-temperature solder in 3D packaging processes.The influence of Sb incorporation on the structure and properties of SnBiIn solder at an equal molar ratio is investigated.It is demonstrated that Sb incorporation facilitates the formation of SnIn phase and induces the precipitation of spherical Bi particles.Furthermore,the concentration of Sb directly affects the morphologies of both Bi and SbIn phases.The amount of Sb also directly impacts the morphologies of Bi and SbIn phases,resulting in distinct solid solution and second-phase strengthening effects.These effects consequently alter the properties of the solder.This phenomenon arises because Sb hinders atomic diffusion within the joint,leading to the formation of thin Cu_(6)(Sn,In)_(5) intermetallic compounds.It can be reasonably inferred that lead-free low-temperature solders,based on high-entropy alloy multicomponent compositions and engineered via elemental modulation,show promise for successful applications in electronic packaging.
