By measuring and analyzing infrared thermal image of the specimen in static load tensile test process, it was studied that the influence of the undercut defects and double-sided dressing method on the deformation beha...By measuring and analyzing infrared thermal image of the specimen in static load tensile test process, it was studied that the influence of the undercut defects and double-sided dressing method on the deformation behavior of the laser welded joint specimens of TC4 titanium alloy. The results showed that for the unmodified specimens, the yield phenomenon occurs first in the region of the joint, but the undercut value has an effect on the stress and strain of starting to yield phenomenon, and a great effect on the plastic deformation behavior.When the undercut is less than a certain value, the large plastic deformation occurs in the base metal region and the plasticity of the specimen is comparable to that of the base metal, but the larger undercut defect results in a concentrated plastic deformation in the joint region and rapidly failed in this region. But the double-sided dressing specimen is significantly different. The physical yield is no longer concentrated in the joint region, but at the same time occurs in the several regions including joint and the base metal. And the plastic deformation mainly occurs in the base material area, similar to that of the base material.展开更多
Mesoporous LiFePO4/C composites containing 80 wt% of highly dispersed LiFePO4 nanoparticles(4-6 nm) were fabricated using bimodal mesoporous carbon(BMC) as continuous conductive networks. The unique pore structure of ...Mesoporous LiFePO4/C composites containing 80 wt% of highly dispersed LiFePO4 nanoparticles(4-6 nm) were fabricated using bimodal mesoporous carbon(BMC) as continuous conductive networks. The unique pore structure of BMC not only promises good particle connectivity for LiFePO4, but also acts as a rigid nano-confinement support that controls the particle size. Furthermore, the capacities were investigated respectively based on the weight of LiFePO4 and the whole composite. When calculated based on the weight of the whole composite, it is 120 mAh·g-1at 0.1 C of the high loading electrode and 42 mAh·g-1at 10 C of the low loading electrode. The electrochemical performance shows that high LiFePO4 loading benefits large tap density and contributes to the energy storage at low rates, while the electrode with low content of LiFePO4 displays superior high rate performance, which can mainly be due to the small particle size, good dispersion and high utilization of the active material, thus leading to a fast ion and electron diffusion.展开更多
The low cycle fatigue strength properties of the additively manufactured Ti-6Al-4V alloy are experimentally investi-gated under proportional and nonproportional multiaxial loading.The fatigue tests were conducted usin...The low cycle fatigue strength properties of the additively manufactured Ti-6Al-4V alloy are experimentally investi-gated under proportional and nonproportional multiaxial loading.The fatigue tests were conducted using hollow cylinder specimens with and without heat treatments,at room temperature in air.Two fatigue tests were conducted:one for proportional loading and one for nonproportional loading.The proportional loading was represented by a push-pull strain path(PP)and the nonproportional loading by a circle strain path(Cl).The failure lives of the additively manufactured specimens were clearly reduced drastically by internal voids and defects.However,the sizes of the defects were measured,and the defects were found not to cause a reduction in fatigue strength above a critical size.The fracture surface was observed using scanning electron microscopy to investigate the fracture mechanisms of the additively manufactured specimens under the two types of strain paths.Different fracture patterns were recognized for each strain paths;however,both showed retention of the crack propagation,despite the presence of numerous defects,probably because of the interaction of the defects.The crack propagation properties of the materials with numerous defects under nonproportional multiaxial loading were clarified to increase the reliability of the additively manufactured components.展开更多
This work studied CuO/CeO2-Co3O4 with wt% Ce:Co ratio 95:5 for selective CO oxidation with effect of? wt% Cu loading. The catalysts were prepared by co-precipitation. Characterizations of catalysts were carried out by...This work studied CuO/CeO2-Co3O4 with wt% Ce:Co ratio 95:5 for selective CO oxidation with effect of? wt% Cu loading. The catalysts were prepared by co-precipitation. Characterizations of catalysts were carried out by XRD and BET techniques. The results showed a good dispersion of CuO for 5 wt% Cu loading catalysts and showed high specific surface area of catalyst. For selective CO oxidation, both 5CuO and 30CuO catalysts could remove completely CO in the presence of excess hydrogen at 423 K and 20CuO could eliminate CO completely at 443 K. Moreover, considering the selectivity to CO oxidation, the 5CuO catalyst has shown the highest selectivity of 85% while the 30CuO catalyst obtains the selectivity of 65% at the reaction temperature of 423 K.展开更多
The article introduces a finite element procedure using the bilinear quadrilateral element or four-node rectangular element(namely Q4 element) based on a refined first-order shear deformation theory(rFSDT) and Monte C...The article introduces a finite element procedure using the bilinear quadrilateral element or four-node rectangular element(namely Q4 element) based on a refined first-order shear deformation theory(rFSDT) and Monte Carlo simulation(MCS), so-called refined stochastic finite element method to investigate the random vibration of functionally graded material(FGM) plates subjected to the moving load.The advantage of the proposed method is to use r-FSDT to improve the accuracy of classical FSDT, satisfy the stress-free condition at the plate boundaries, and combine with MCS to analyze the vibration of the FGM plate when the parameter inputs are random quantities following a normal distribution. The obtained results show that the distribution characteristics of the vibration response of the FGM plate depend on the standard deviation of the input parameters and the velocity of the moving load.Furthermore, the numerical results in this study are expected to contribute to improving the understanding of FGM plates subjected to moving loads with uncertain input parameters.展开更多
A cross-sectional study was conducted at the “Centre de l’Appui Psycho-Médico-Social (APMS)” which is a centre for Psychological and Medical Support in N'Djamena (Chad) from January to March 2014. The aim ...A cross-sectional study was conducted at the “Centre de l’Appui Psycho-Médico-Social (APMS)” which is a centre for Psychological and Medical Support in N'Djamena (Chad) from January to March 2014. The aim of this study was to evaluate the correlation between asymptomatic bacteriuria (ASB) and viral load level and CD4 count in seventy-six (76) HIV-1 infected pregnant women on antiretroviral therapy (ART). Urine culture and bacteria identification were performed by using a chromogenic culture medium (UriselectR4). T CD4+ lymphocytes count and viral load measurement were done respectively on PIMATM test and Abbott m2000 RealTime HIV-1. In this study, 25 (32.9%) pregnant women were carrying ASB and major bacteria;Escherichia coli and Streptococcus agalactiae known to cause neonatal meningitis to newborns were identified. Bacteria were isolated mainly in women with CD4 lymphocytes 3log (70%) (19/25). Besides the prevention of mother to child transmission of HIV, which remains a goal, it is important to prevent also the transmission of other microorganisms causing neonatal infections. Our findings support the needs to do bacteriological analysis of urine in every HIV-infected pregnant woman at least in late pregnancy.展开更多
In Sub-Saharan Africa, HIV affects lots of women of childbearing age;without prevention they can transmit the virus to their child. A cross-sectional study was conducted in the center of Psycho Medico-Social Support (...In Sub-Saharan Africa, HIV affects lots of women of childbearing age;without prevention they can transmit the virus to their child. A cross-sectional study was conducted in the center of Psycho Medico-Social Support (APMS) in N’Djamena, Chad from January 2014 to March 2015. Our sampling concerned HIV-1 infected pregnant women followed up for PMTCT and their newborn. CD4+ lymphocytes and HIV-1 viral load were tested respectively with PIMATM and Abbott m2000 Real Time in mothers. Early infant diagnosis of HIV-1 was done in Children using PCR tool (Abbott m2000 Real Time). Pregnant women included in the study had a median age of 25 years (IQR, 22 - 30 years). Most of them (75.6%) (34/45), were under combination ART (TDF + 3TC or FTC + EFV). The median duration on ART was 4 month (IQR [3 - 5 months]). Nevirapine syrup was administrated to newborns as prophylaxis at least for the first six weeks of life until EID was done. At ART initiation, mothers’ LTCD4+ median was 249 cells/mm3 (IQR: 95 - 674 cells/mm3). After a median duration of 4 months on ART, LTCD4+ median was 530 cells/mm3 (IQR [263 - 1220 cells/mm3]). Viral load assessment in mothers showed that 15.5% (7/45) were undetectable, 75.6% (34/45) were detectable with a VL < 3log copies/ml and 8.8% (4/45) at virologic failure (VL > 3log copies/ ml). Four (11.4%) of 35 children included were tested positive at EID for HIV-1. Antiretroviral treatment management in pregnant women can improve their health and reduce the risk of MTCT. Availability of virologic monitoring in routine is essential for pregnant women in resources limited setting for preventing HIV transmission to their new-born and keep them alive.展开更多
基金Project was supported by National Defense Basic Scientific Research Program of China (JCKY2016205A001)。
文摘By measuring and analyzing infrared thermal image of the specimen in static load tensile test process, it was studied that the influence of the undercut defects and double-sided dressing method on the deformation behavior of the laser welded joint specimens of TC4 titanium alloy. The results showed that for the unmodified specimens, the yield phenomenon occurs first in the region of the joint, but the undercut value has an effect on the stress and strain of starting to yield phenomenon, and a great effect on the plastic deformation behavior.When the undercut is less than a certain value, the large plastic deformation occurs in the base metal region and the plasticity of the specimen is comparable to that of the base metal, but the larger undercut defect results in a concentrated plastic deformation in the joint region and rapidly failed in this region. But the double-sided dressing specimen is significantly different. The physical yield is no longer concentrated in the joint region, but at the same time occurs in the several regions including joint and the base metal. And the plastic deformation mainly occurs in the base material area, similar to that of the base material.
基金supported by the National Natural Science Foundation of China (NSFC 21103184)the Ph.D.Programs Foundation (20100041110017) of Ministry of Education of Chinathe Fundamental Research Funds for the Central Universities
文摘Mesoporous LiFePO4/C composites containing 80 wt% of highly dispersed LiFePO4 nanoparticles(4-6 nm) were fabricated using bimodal mesoporous carbon(BMC) as continuous conductive networks. The unique pore structure of BMC not only promises good particle connectivity for LiFePO4, but also acts as a rigid nano-confinement support that controls the particle size. Furthermore, the capacities were investigated respectively based on the weight of LiFePO4 and the whole composite. When calculated based on the weight of the whole composite, it is 120 mAh·g-1at 0.1 C of the high loading electrode and 42 mAh·g-1at 10 C of the low loading electrode. The electrochemical performance shows that high LiFePO4 loading benefits large tap density and contributes to the energy storage at low rates, while the electrode with low content of LiFePO4 displays superior high rate performance, which can mainly be due to the small particle size, good dispersion and high utilization of the active material, thus leading to a fast ion and electron diffusion.
基金Supported by Japan Society for the Promotion of Science KAKENHI(Grant No.18H05256).
文摘The low cycle fatigue strength properties of the additively manufactured Ti-6Al-4V alloy are experimentally investi-gated under proportional and nonproportional multiaxial loading.The fatigue tests were conducted using hollow cylinder specimens with and without heat treatments,at room temperature in air.Two fatigue tests were conducted:one for proportional loading and one for nonproportional loading.The proportional loading was represented by a push-pull strain path(PP)and the nonproportional loading by a circle strain path(Cl).The failure lives of the additively manufactured specimens were clearly reduced drastically by internal voids and defects.However,the sizes of the defects were measured,and the defects were found not to cause a reduction in fatigue strength above a critical size.The fracture surface was observed using scanning electron microscopy to investigate the fracture mechanisms of the additively manufactured specimens under the two types of strain paths.Different fracture patterns were recognized for each strain paths;however,both showed retention of the crack propagation,despite the presence of numerous defects,probably because of the interaction of the defects.The crack propagation properties of the materials with numerous defects under nonproportional multiaxial loading were clarified to increase the reliability of the additively manufactured components.
文摘This work studied CuO/CeO2-Co3O4 with wt% Ce:Co ratio 95:5 for selective CO oxidation with effect of? wt% Cu loading. The catalysts were prepared by co-precipitation. Characterizations of catalysts were carried out by XRD and BET techniques. The results showed a good dispersion of CuO for 5 wt% Cu loading catalysts and showed high specific surface area of catalyst. For selective CO oxidation, both 5CuO and 30CuO catalysts could remove completely CO in the presence of excess hydrogen at 423 K and 20CuO could eliminate CO completely at 443 K. Moreover, considering the selectivity to CO oxidation, the 5CuO catalyst has shown the highest selectivity of 85% while the 30CuO catalyst obtains the selectivity of 65% at the reaction temperature of 423 K.
文摘The article introduces a finite element procedure using the bilinear quadrilateral element or four-node rectangular element(namely Q4 element) based on a refined first-order shear deformation theory(rFSDT) and Monte Carlo simulation(MCS), so-called refined stochastic finite element method to investigate the random vibration of functionally graded material(FGM) plates subjected to the moving load.The advantage of the proposed method is to use r-FSDT to improve the accuracy of classical FSDT, satisfy the stress-free condition at the plate boundaries, and combine with MCS to analyze the vibration of the FGM plate when the parameter inputs are random quantities following a normal distribution. The obtained results show that the distribution characteristics of the vibration response of the FGM plate depend on the standard deviation of the input parameters and the velocity of the moving load.Furthermore, the numerical results in this study are expected to contribute to improving the understanding of FGM plates subjected to moving loads with uncertain input parameters.
文摘A cross-sectional study was conducted at the “Centre de l’Appui Psycho-Médico-Social (APMS)” which is a centre for Psychological and Medical Support in N'Djamena (Chad) from January to March 2014. The aim of this study was to evaluate the correlation between asymptomatic bacteriuria (ASB) and viral load level and CD4 count in seventy-six (76) HIV-1 infected pregnant women on antiretroviral therapy (ART). Urine culture and bacteria identification were performed by using a chromogenic culture medium (UriselectR4). T CD4+ lymphocytes count and viral load measurement were done respectively on PIMATM test and Abbott m2000 RealTime HIV-1. In this study, 25 (32.9%) pregnant women were carrying ASB and major bacteria;Escherichia coli and Streptococcus agalactiae known to cause neonatal meningitis to newborns were identified. Bacteria were isolated mainly in women with CD4 lymphocytes 3log (70%) (19/25). Besides the prevention of mother to child transmission of HIV, which remains a goal, it is important to prevent also the transmission of other microorganisms causing neonatal infections. Our findings support the needs to do bacteriological analysis of urine in every HIV-infected pregnant woman at least in late pregnancy.
文摘In Sub-Saharan Africa, HIV affects lots of women of childbearing age;without prevention they can transmit the virus to their child. A cross-sectional study was conducted in the center of Psycho Medico-Social Support (APMS) in N’Djamena, Chad from January 2014 to March 2015. Our sampling concerned HIV-1 infected pregnant women followed up for PMTCT and their newborn. CD4+ lymphocytes and HIV-1 viral load were tested respectively with PIMATM and Abbott m2000 Real Time in mothers. Early infant diagnosis of HIV-1 was done in Children using PCR tool (Abbott m2000 Real Time). Pregnant women included in the study had a median age of 25 years (IQR, 22 - 30 years). Most of them (75.6%) (34/45), were under combination ART (TDF + 3TC or FTC + EFV). The median duration on ART was 4 month (IQR [3 - 5 months]). Nevirapine syrup was administrated to newborns as prophylaxis at least for the first six weeks of life until EID was done. At ART initiation, mothers’ LTCD4+ median was 249 cells/mm3 (IQR: 95 - 674 cells/mm3). After a median duration of 4 months on ART, LTCD4+ median was 530 cells/mm3 (IQR [263 - 1220 cells/mm3]). Viral load assessment in mothers showed that 15.5% (7/45) were undetectable, 75.6% (34/45) were detectable with a VL < 3log copies/ml and 8.8% (4/45) at virologic failure (VL > 3log copies/ ml). Four (11.4%) of 35 children included were tested positive at EID for HIV-1. Antiretroviral treatment management in pregnant women can improve their health and reduce the risk of MTCT. Availability of virologic monitoring in routine is essential for pregnant women in resources limited setting for preventing HIV transmission to their new-born and keep them alive.
