X-ray emission from the collisions of 3 MeV Ar^(11+)ions with V,Fe,Co,Ni,Cu,and Zn is investigated.Both the x-rays of the target atom and projectile are observed simultaneously.The x-ray yield is extracted from the or...X-ray emission from the collisions of 3 MeV Ar^(11+)ions with V,Fe,Co,Ni,Cu,and Zn is investigated.Both the x-rays of the target atom and projectile are observed simultaneously.The x-ray yield is extracted from the original count.The inner-shell ionization cross section is estimated by the binary encounter approximation model and compared with the experimental result.The remarkable result is that the Ar K-shell x-ray yield is diminished with the target atomic number increasing,which is completely opposite to the theoretical calculation.That is interpreted by the competitive consumption of the energy loss for the ionization of inner-shell electrons between the projectile and target atom.展开更多
BACKGROUND Maternal sepsis is a major cause of gestational morbidity and neonatal mortality worldwide and particularly in China.AIM To evaluate the etiology of maternal sepsis and further identify its risk factors.MET...BACKGROUND Maternal sepsis is a major cause of gestational morbidity and neonatal mortality worldwide and particularly in China.AIM To evaluate the etiology of maternal sepsis and further identify its risk factors.METHODS In this retrospective study,we evaluated 70698 obstetric patients who were admitted to the Third Affiliated Hospital of Guangzhou Medical University between January 1,2009 and June 30,2018.Subjects were divided into sepsis group and non-sepsis group based on the incidence of sepsis.Data about medical history(surgical and obstetric history)and demographic information were collected.The Mann-Whitney U test was used to compare patient age,gestational age and duration of hospitalization between the two groups.Univariate and multivariate logistic regression models were used to analyze the etiology and the risk factors for maternal sepsis.Unadjusted and adjusted odds ratios(OR)are reported.RESULTS A total of 561 of 70698 obstetric patients were diagnosed with infection;of the infected patients,492 had non-sepsis associated infection(87.7%),while 69 had sepsis(12.3%).The morbidity rate of maternal sepsis was 9.76/10000;the fatality rate in the sepsis group was 11.6%(8/69).Emergency admission(OR=2.183)or transfer(OR=2.870),irregular prenatal care(OR=2.953),labor induction(OR=4.665),cervical cerclage(OR=14.214),first trimester(OR=6.806)and second trimester(OR=2.09)were significant risk factors for maternal sepsis.CONCLUSION Mode of admission,poor prenatal care,labor induction,cervical cerclage,first trimester and second trimester pregnancy were risk factors for maternal sepsis.Escherichia coli was the most common causative organism for maternal sepsis,and the uterus was the most common site of infection.展开更多
The L-shell x-ray of Nd has been obtained for 300-600 keV He2+ions impacting,and compared with that produced by H+and H2+ions.The threshold of projectile kinetic energy for L-shell ionization of Nd is crudely verified...The L-shell x-ray of Nd has been obtained for 300-600 keV He2+ions impacting,and compared with that produced by H+and H2+ions.The threshold of projectile kinetic energy for L-shell ionization of Nd is crudely verified in the energy region of about 300-400 keV.It is found that the energy of the distinct L-subshell x-rays has a blue shift.The relative intensity ratios of Lβ_(1,3,4)and Lβ_(2,15)to Lα_(1,2)x-ray are enlarged compared to the atomic data,and they decrease with the increase of the incident energy,and increase with increasing the effective nuclear charge of the incident ions.That is interpreted by the multiple ionization of outer-shells induced by light ions.展开更多
CME is one of the important events in the sun-earth system as it can induce geomagnetic disturbance and an associated space environment effect.It is of special significance to predict whether CME will reach the Earth ...CME is one of the important events in the sun-earth system as it can induce geomagnetic disturbance and an associated space environment effect.It is of special significance to predict whether CME will reach the Earth and when it will arrive.In this paper,we firstly built a new multiple association list for 215 different events with 18 characteristics including CME features,eruption region coordinates and solar wind parameters.Based on the CME list,we designed a novel model based on the principle of the recommendation algorithm to predict the arrival time of CMEs.According to the two commonly used calculation methods in the recommendation system,cosine distance and Euclidean distance,a controlled trial was carried out respectively.Every feature has been found to have its own appropriate weight.The error analysis indicates the result using the Euclidean distance similarity is much better than that using cosine distance similarity.The mean absolute error and root mean square error of test data in the Euclidean distance are 11.78 and 13.77 h,close to the average level of other CME models issued in the CME scoreboard,which verifies the effectiveness of the recommendation algorithm.This work gives a new endeavor using the recommendation algorithm,and is expected to induce other applications in space weather prediction.展开更多
Nb_(2)P_(5) is a recently discovered Bardeen,Cooper,Schrieffer theory s-wave superconductor hosting nontrivial topological nodal-line structure,which could serve as an excellent platform for studying the interplay bet...Nb_(2)P_(5) is a recently discovered Bardeen,Cooper,Schrieffer theory s-wave superconductor hosting nontrivial topological nodal-line structure,which could serve as an excellent platform for studying the interplay between the superconductivity and nontrivial topological states.We report herein the superconducting and structural properties of Nb2P5studied by measuring the electrical resistivity and structure under high pressure up to ~28 GPa and performing first principles calculations.The superconducting transition temperature TCdecreases with applied pressure,and reaches a minimum of 1.9 K at ~20.0 GPa,followed by a continuous enhancement up to 50.0 GPa without saturation.Furthermore,at pressures above ~8.2 GPa,it is likely that a second superconducting transition appears and coexists with the initial one even up to~28 GPa.Theoretical calculations rule out the correlation between the second superconducting-like transition and structure.Moreover,the Nb2P5showed remarkable axial anisotropic compressibility,in which the b-axis is more compressible than the a-and c-axes.The variation of TCis discussed via considering the evolution of density of states around the Fermi level and the phonon spectrum.展开更多
Purpose::COVID-19 is also referred to as a typical viral septic pulmonary infection by 2019-nCoV.However,little is known regarding its characteristics in terms of systemic inflammation and organ injury,especially comp...Purpose::COVID-19 is also referred to as a typical viral septic pulmonary infection by 2019-nCoV.However,little is known regarding its characteristics in terms of systemic inflammation and organ injury,especially compared with classical bacterial sepsis.This article aims to investigate the clinical characteristics and prognosis between COVID-19-associated sepsis and classic bacterial-induced sepsis.Methods::In this retrospective cohort study,septic patients with COVID-19 in the intensive care unit(ICU)of a government-designed therapy center in Shenzhen,China between January 14,2020 and March 10,2020,and septic patients induced by carbapenem-resistant klebsiella pneumonia(CrKP)admitted to the ICU of the Second People's Hospital of Shenzhen,China between January 1,2014 and October 30,2019 were enrolled.Demographic and clinical parameters including comorbidities,critical illness scores,treatment,and laboratory data,as well as prognosis were compared between the two groups.Risk factors for mortality and survival rate were analyzed using multivariable logistic regression and survival curve,respectively.Results::A total of 107 patients with COVID-19 and 63 patients with CrKP were enrolled.A direct comparison between the two groups demonstrated more serious degrees of primary lung injury following 2019-nCoV infection(indicated by lower PaO 2/FiO 2),but milder systemic inflammatory response,lower sequential organ failure assessment score and better functions of the organs like heart,liver,kidney,coagulation,and circulation.However,the acquired immunosuppression presented in COVID-19 patients was more severe,which presented as lower lymphocyte counts(0.8×109/L vs.0.9×109/L).Moreover,the proportion of COVID-19 patients treated with corticosteroid therapy and extracorporeal membrane oxygenation was larger compared with CrKP patients(78.5%vs.38.1%and 6.5%vs.0,respectively)who required less invasive mechanical ventilation(31.6%vs.54.0%).The incidence of hospitalized mortality and length of ICU stay and total hospital stay were also lower or shorter in viral sepsis(12.1%vs.39.7%,6.5 days vs.23.0 days and 21.0 days vs.33.0 days,respectively)(all p<0.001).Similar results were obtained after being adjusted by age,gender,comorbidity and PaO2/FiO2.Lymphocytopenia and high acute physiology and chronic health evaluation II scores were common risk factors for in-hospital death.While the death cases of COVID-19 sepsis mostly occurred at the later stages of patients’hospital stay.Conclusion::Critical COVID-19 shares clinical characteristics with classical bacterial sepsis,but the degree of systemic inflammatory response,secondary organ damage and mortality rate are less severe.However,following 2019-nCoV infection,the level of immunosuppression may be increased and thus induce in more death at the later stage of patients’hospitalstay.展开更多
The microstructures,mechanical properties and fracture behaviors of a new WE43 alloy(Mg-4 Y-1.6 Nd-2 Sm-0.5 Zr)were investigated.The microstructure of the as-cast alloy includes a Mg matrix,Mg_(41)Sm_(5),Mg_(41)Nd_(5)...The microstructures,mechanical properties and fracture behaviors of a new WE43 alloy(Mg-4 Y-1.6 Nd-2 Sm-0.5 Zr)were investigated.The microstructure of the as-cast alloy includes a Mg matrix,Mg_(41)Sm_(5),Mg_(41)Nd_(5)and Mg_(24)Y_(5)eutectic phases,as well asβ-phase.After an optimal solution treatment,the eutectic phases are almost completely dissolved;only a few spots of blocky Mg-Y compounds remain at grain boundaries.After an aging treatment,a large amount ofβ’-phases are dispersed and precipitated at the grain interior,which provides good comprehensive mechanical properties of the alloy,particularly in the under-aged state.The tensile strength is up to290 MPa,the yield strength reaches 209 MPa,and the elongation is slightly improved.Furthermore,the fracture behaviors of the studied alloy in different states significantly differ.In addition,a comparison of mechanical properties of the new WE43,traditional WE43 and other modified WE43 alloys is presented.展开更多
Objectives:To investigate whether a precise circular resection of the uterine tissue at the placental attachment part is effective in cases with placenta previa complicated with placenta percreta (PPWPP).Methods:Patie...Objectives:To investigate whether a precise circular resection of the uterine tissue at the placental attachment part is effective in cases with placenta previa complicated with placenta percreta (PPWPP).Methods:Patients diagnosed with PPWPP were assessed for pregnancy termination at 34-36 weeks of gestation.During the operation,we performed circular resection of the uterine tissue at the placental attachment part.Then the characteristics of the operation and the follow-ups were recorded.Results:During the operation,the vital signs were stable.The mean intraoperative blood loss,packed red blood cells units transfusion,fresh frozen plasma transfusion,and operation time were 2140 mL,6 U,440 mL,and 179.8 minutes,respectively.There was no bowel,ureter,or bladder injury.And there was no patient transferred to the ICU after operation.The mean postoperative blood loss was 458.6mL.There was no fever,infection,intestinal obstruction,or other complications after operation during the hospitalization.The shape and the blood flow of the uterus were normal.After the patients were discharged,one had developed cesarean scar diverticulum.The mean lochia duration was 30 days.The menstrual cycle and volume were as before.The shape and the blood flow of the uterus and the ovarian were normal.Conclusions:The circular resection following end-to-end anastomosis is an effective precision surgical approach for PPWPP.It can achieve the purpose of hemostasis while maximizing the protection of organ function and reducing surgical trauma.展开更多
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0402300)the National Natural Science Foundation of China(Grant Nos.11505248,11775042,11875096,and 11605147)the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.20JK0975)+2 种基金the Scientific Research Plan of Science and Technology Department of Shaanxi Province,China(Grant Nos.2021JQ-812 and 2020JM-624)Open Funds of MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions(Grant No.MPCEC201901)Xianyang Normal University Science Foundation(Grant Nos.XSYK20009 and XSYK20024).
文摘X-ray emission from the collisions of 3 MeV Ar^(11+)ions with V,Fe,Co,Ni,Cu,and Zn is investigated.Both the x-rays of the target atom and projectile are observed simultaneously.The x-ray yield is extracted from the original count.The inner-shell ionization cross section is estimated by the binary encounter approximation model and compared with the experimental result.The remarkable result is that the Ar K-shell x-ray yield is diminished with the target atomic number increasing,which is completely opposite to the theoretical calculation.That is interpreted by the competitive consumption of the energy loss for the ionization of inner-shell electrons between the projectile and target atom.
基金National Natural Science Foundation of China,No.81830045 and No.82071652.
文摘BACKGROUND Maternal sepsis is a major cause of gestational morbidity and neonatal mortality worldwide and particularly in China.AIM To evaluate the etiology of maternal sepsis and further identify its risk factors.METHODS In this retrospective study,we evaluated 70698 obstetric patients who were admitted to the Third Affiliated Hospital of Guangzhou Medical University between January 1,2009 and June 30,2018.Subjects were divided into sepsis group and non-sepsis group based on the incidence of sepsis.Data about medical history(surgical and obstetric history)and demographic information were collected.The Mann-Whitney U test was used to compare patient age,gestational age and duration of hospitalization between the two groups.Univariate and multivariate logistic regression models were used to analyze the etiology and the risk factors for maternal sepsis.Unadjusted and adjusted odds ratios(OR)are reported.RESULTS A total of 561 of 70698 obstetric patients were diagnosed with infection;of the infected patients,492 had non-sepsis associated infection(87.7%),while 69 had sepsis(12.3%).The morbidity rate of maternal sepsis was 9.76/10000;the fatality rate in the sepsis group was 11.6%(8/69).Emergency admission(OR=2.183)or transfer(OR=2.870),irregular prenatal care(OR=2.953),labor induction(OR=4.665),cervical cerclage(OR=14.214),first trimester(OR=6.806)and second trimester(OR=2.09)were significant risk factors for maternal sepsis.CONCLUSION Mode of admission,poor prenatal care,labor induction,cervical cerclage,first trimester and second trimester pregnancy were risk factors for maternal sepsis.Escherichia coli was the most common causative organism for maternal sepsis,and the uterus was the most common site of infection.
基金supported by the National Key R&D Program of China(Grant No.2017YFA0402300)the National Natural Science Foundation of China(Grant Nos.11505248,11775042,11875096,and 11605147)+3 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department(Grant No.20JK0975)Scientific Research Plan of Science and Technology Department of Shaanxi Province,China(Grant No.2021JQ-812)Xianyang Normal University Science Foundation(Grant Nos.XSYK20024 and XSYK20009)the academic leader of Xianyang Normal University(Grant No.XSYXSDT202108)。
文摘The L-shell x-ray of Nd has been obtained for 300-600 keV He2+ions impacting,and compared with that produced by H+and H2+ions.The threshold of projectile kinetic energy for L-shell ionization of Nd is crudely verified in the energy region of about 300-400 keV.It is found that the energy of the distinct L-subshell x-rays has a blue shift.The relative intensity ratios of Lβ_(1,3,4)and Lβ_(2,15)to Lα_(1,2)x-ray are enlarged compared to the atomic data,and they decrease with the increase of the incident energy,and increase with increasing the effective nuclear charge of the incident ions.That is interpreted by the multiple ionization of outer-shells induced by light ions.
基金supported by a NASA Heliophysics Guest Investigator Grantsupported by the National Natural Science Foundation of China (Grant Nos.12071166 and 42074224)。
文摘CME is one of the important events in the sun-earth system as it can induce geomagnetic disturbance and an associated space environment effect.It is of special significance to predict whether CME will reach the Earth and when it will arrive.In this paper,we firstly built a new multiple association list for 215 different events with 18 characteristics including CME features,eruption region coordinates and solar wind parameters.Based on the CME list,we designed a novel model based on the principle of the recommendation algorithm to predict the arrival time of CMEs.According to the two commonly used calculation methods in the recommendation system,cosine distance and Euclidean distance,a controlled trial was carried out respectively.Every feature has been found to have its own appropriate weight.The error analysis indicates the result using the Euclidean distance similarity is much better than that using cosine distance similarity.The mean absolute error and root mean square error of test data in the Euclidean distance are 11.78 and 13.77 h,close to the average level of other CME models issued in the CME scoreboard,which verifies the effectiveness of the recommendation algorithm.This work gives a new endeavor using the recommendation algorithm,and is expected to induce other applications in space weather prediction.
基金support by the Postgraduate Education Reform and Quality Improvement Project of Henan Province (YJS2021AL098, YJS2021JD20, 2022YJSKC03)Key Scientific Research Projects of Henan Province (162102210238, 202102210216)Postgraduate Education Innovation Program of Zhengzhou University of Aeronautics (2020CX20, 2021YJSJGZX11, 2020YJSJD1)。
文摘Nb_(2)P_(5) is a recently discovered Bardeen,Cooper,Schrieffer theory s-wave superconductor hosting nontrivial topological nodal-line structure,which could serve as an excellent platform for studying the interplay between the superconductivity and nontrivial topological states.We report herein the superconducting and structural properties of Nb2P5studied by measuring the electrical resistivity and structure under high pressure up to ~28 GPa and performing first principles calculations.The superconducting transition temperature TCdecreases with applied pressure,and reaches a minimum of 1.9 K at ~20.0 GPa,followed by a continuous enhancement up to 50.0 GPa without saturation.Furthermore,at pressures above ~8.2 GPa,it is likely that a second superconducting transition appears and coexists with the initial one even up to~28 GPa.Theoretical calculations rule out the correlation between the second superconducting-like transition and structure.Moreover,the Nb2P5showed remarkable axial anisotropic compressibility,in which the b-axis is more compressible than the a-and c-axes.The variation of TCis discussed via considering the evolution of density of states around the Fermi level and the phonon spectrum.
基金This work was supported by grants from the PLA Logistics Research Project of China[18CXZ030,CWH17L020,17CXZ008]Sanming Project of Medicine in Shenzhen(SZSM20162011)Shenzhen Second People's Hospital Clinical Research Fund of Guangdong Province High-level Hospital Construction Project(Grant No 20173357201815,No 20193357003,No 20203357014).
文摘Purpose::COVID-19 is also referred to as a typical viral septic pulmonary infection by 2019-nCoV.However,little is known regarding its characteristics in terms of systemic inflammation and organ injury,especially compared with classical bacterial sepsis.This article aims to investigate the clinical characteristics and prognosis between COVID-19-associated sepsis and classic bacterial-induced sepsis.Methods::In this retrospective cohort study,septic patients with COVID-19 in the intensive care unit(ICU)of a government-designed therapy center in Shenzhen,China between January 14,2020 and March 10,2020,and septic patients induced by carbapenem-resistant klebsiella pneumonia(CrKP)admitted to the ICU of the Second People's Hospital of Shenzhen,China between January 1,2014 and October 30,2019 were enrolled.Demographic and clinical parameters including comorbidities,critical illness scores,treatment,and laboratory data,as well as prognosis were compared between the two groups.Risk factors for mortality and survival rate were analyzed using multivariable logistic regression and survival curve,respectively.Results::A total of 107 patients with COVID-19 and 63 patients with CrKP were enrolled.A direct comparison between the two groups demonstrated more serious degrees of primary lung injury following 2019-nCoV infection(indicated by lower PaO 2/FiO 2),but milder systemic inflammatory response,lower sequential organ failure assessment score and better functions of the organs like heart,liver,kidney,coagulation,and circulation.However,the acquired immunosuppression presented in COVID-19 patients was more severe,which presented as lower lymphocyte counts(0.8×109/L vs.0.9×109/L).Moreover,the proportion of COVID-19 patients treated with corticosteroid therapy and extracorporeal membrane oxygenation was larger compared with CrKP patients(78.5%vs.38.1%and 6.5%vs.0,respectively)who required less invasive mechanical ventilation(31.6%vs.54.0%).The incidence of hospitalized mortality and length of ICU stay and total hospital stay were also lower or shorter in viral sepsis(12.1%vs.39.7%,6.5 days vs.23.0 days and 21.0 days vs.33.0 days,respectively)(all p<0.001).Similar results were obtained after being adjusted by age,gender,comorbidity and PaO2/FiO2.Lymphocytopenia and high acute physiology and chronic health evaluation II scores were common risk factors for in-hospital death.While the death cases of COVID-19 sepsis mostly occurred at the later stages of patients’hospital stay.Conclusion::Critical COVID-19 shares clinical characteristics with classical bacterial sepsis,but the degree of systemic inflammatory response,secondary organ damage and mortality rate are less severe.However,following 2019-nCoV infection,the level of immunosuppression may be increased and thus induce in more death at the later stage of patients’hospitalstay.
基金financially supported by the Natural Science Foundation of Heilongjiang Province(No.E2018045)。
文摘The microstructures,mechanical properties and fracture behaviors of a new WE43 alloy(Mg-4 Y-1.6 Nd-2 Sm-0.5 Zr)were investigated.The microstructure of the as-cast alloy includes a Mg matrix,Mg_(41)Sm_(5),Mg_(41)Nd_(5)and Mg_(24)Y_(5)eutectic phases,as well asβ-phase.After an optimal solution treatment,the eutectic phases are almost completely dissolved;only a few spots of blocky Mg-Y compounds remain at grain boundaries.After an aging treatment,a large amount ofβ’-phases are dispersed and precipitated at the grain interior,which provides good comprehensive mechanical properties of the alloy,particularly in the under-aged state.The tensile strength is up to290 MPa,the yield strength reaches 209 MPa,and the elongation is slightly improved.Furthermore,the fracture behaviors of the studied alloy in different states significantly differ.In addition,a comparison of mechanical properties of the new WE43,traditional WE43 and other modified WE43 alloys is presented.
基金This study was supported by the National Key R&D Program of China(2016YFC1000405)Guangdong Natural Science Foundation(2015A030310115)
文摘Objectives:To investigate whether a precise circular resection of the uterine tissue at the placental attachment part is effective in cases with placenta previa complicated with placenta percreta (PPWPP).Methods:Patients diagnosed with PPWPP were assessed for pregnancy termination at 34-36 weeks of gestation.During the operation,we performed circular resection of the uterine tissue at the placental attachment part.Then the characteristics of the operation and the follow-ups were recorded.Results:During the operation,the vital signs were stable.The mean intraoperative blood loss,packed red blood cells units transfusion,fresh frozen plasma transfusion,and operation time were 2140 mL,6 U,440 mL,and 179.8 minutes,respectively.There was no bowel,ureter,or bladder injury.And there was no patient transferred to the ICU after operation.The mean postoperative blood loss was 458.6mL.There was no fever,infection,intestinal obstruction,or other complications after operation during the hospitalization.The shape and the blood flow of the uterus were normal.After the patients were discharged,one had developed cesarean scar diverticulum.The mean lochia duration was 30 days.The menstrual cycle and volume were as before.The shape and the blood flow of the uterus and the ovarian were normal.Conclusions:The circular resection following end-to-end anastomosis is an effective precision surgical approach for PPWPP.It can achieve the purpose of hemostasis while maximizing the protection of organ function and reducing surgical trauma.