The inflammatory microenvironment and neurotoxicity can hinder neuronal regeneration and functional recovery after spinal cord injury.Ruxolitinib,a JAK-STAT inhibitor,exhibits effectiveness in autoimmune diseases,arth...The inflammatory microenvironment and neurotoxicity can hinder neuronal regeneration and functional recovery after spinal cord injury.Ruxolitinib,a JAK-STAT inhibitor,exhibits effectiveness in autoimmune diseases,arthritis,and managing inflammatory cytokine storms.Although studies have shown the neuroprotective potential of ruxolitinib in neurological trauma,the exact mechanism by which it enhances functional recovery after spinal cord injury,particularly its effect on astrocytes,remains unclear.To address this gap,we established a mouse model of T10 spinal cord contusion and found that ruxolitinib effectively improved hindlimb motor function and reduced the area of spinal cord injury.Transcriptome sequencing analysis showed that ruxolitinib alleviated inflammation and immune response after spinal cord injury,restored EAAT2 expression,reduced glutamate levels,and alleviated excitatory toxicity.Furthermore,ruxolitinib inhibited the phosphorylation of JAK2 and STAT3 in the injured spinal cord and decreased the phosphorylation level of nuclear factor kappa-B and the expression of inflammatory factors interleukin-1β,interleukin-6,and tumor necrosis factor-α.Additionally,in glutamate-induced excitotoxicity astrocytes,ruxolitinib restored EAAT2 expression and increased glutamate uptake by inhibiting the activation of STAT3,thereby reducing glutamate-induced neurotoxicity,calcium influx,oxidative stress,and cell apoptosis,and increasing the complexity of dendritic branching.Collectively,these results indicate that ruxolitinib restores glutamate homeostasis by rescuing the expression of EAAT2 in astrocytes,reduces neurotoxicity,and effectively alleviates inflammatory and immune responses after spinal cord injury,thereby promoting functional recovery after spinal cord injury.展开更多
This study was aimed to introduce a novel entry point for pedicle screw fixation in the thoracic spine and compare it with the traditional entry point. A novel entry point was found with the aim of improving accuracy,...This study was aimed to introduce a novel entry point for pedicle screw fixation in the thoracic spine and compare it with the traditional entry point. A novel entry point was found with the aim of improving accuracy, safety and stability of pedicle screw technique based on anatomical structures of the spine. A total of 76 pieces of normal thoracic CT images at the transverse plane and the thoracic pedicle anatomy of 6 cadaveric specimens were recruited.Transverse pedicle angle(TPA), screw length, screw placement accuracy rate and axial pullout strength of the two different entry point groups were compared. There were significant differences in the TPA, screw length, and the screw placement accuracy rate between the two groups(P〈0.05). The maximum axial pullout strength of the novel entry point group was slightly larger than that of the traditional group. However, the difference was not significant(P 〉 0.05). The novel entry point significantly improved the accuracy, stability and safety of pedicle screw placement.With reference to the advantages above, the new entry point can be used for spinal internal fixations in the thoracic spine.展开更多
The influence of thermal cycling on the microstructure and joint strength of Sn3.5Ag0.75Cu (SAC) and Sn63Pb37 (SnPb) solder joints was investigated. SAC and SnPb solder balls were soldered on 0.1 and 0.9 μm Au fi...The influence of thermal cycling on the microstructure and joint strength of Sn3.5Ag0.75Cu (SAC) and Sn63Pb37 (SnPb) solder joints was investigated. SAC and SnPb solder balls were soldered on 0.1 and 0.9 μm Au finished metallization, respectively. After 1000 thermal cycles between -40℃ and 125℃, a very thin intermetallic compound (IMC) layer containing Au, Sn, Ni, and Cu formed at the interface between SAC solder joints and underneath metallization with 0.1 μm Au finish, and (Au, Ni, Cu)Sn4 and a very thin AuSn-Ni-Cu IMC layer formed between SAC solder joints and underneath metallization with 0.9 μm Au finish. For SnPb solder joints with 0.1 μm Au finish, a thin (Ni, Cu, Au)3Sn4 IMC layer and a Pb-rich layer formed below and above the (Au, Ni)Sn4 IMC, respectively. Cu diffused through Ni layer and was involved into the IMC formation process. Similar interfacial microstructure was also found for SnPb solder joints with 0.9μm Au finish. The results of shear test show that the shear strength of SAC solder joints is consistently higher than that of SnPb eutectic solder joints during thermal cycling.展开更多
The study aimed to demonstrate the feasibility of an extradural nerve anastomosis technique for the restoration of a C5 and C6 avulsion of the brachial plexus.Nine fresh frozen human cadavers were used.The diameters,s...The study aimed to demonstrate the feasibility of an extradural nerve anastomosis technique for the restoration of a C5 and C6 avulsion of the brachial plexus.Nine fresh frozen human cadavers were used.The diameters,sizes,and locations of the extradural spinal nerve roots were observed.The lengths of the extradural spinal nerve roots and the distance between the neighboring nerve root outlets were measured and compared in the cervical segments.In the spinal canal,the ventral and dorsal roots were separated by the dura and arachnoid.The ventral and dorsal roots of C7 had sufficient lengths to anastomose those of C6.The ventral and dorsal of C4 had enough length to be transferred to those of C5,respectively.The feasibility of this extradural nerve anastomosis technique for restoring C5 and C6 avulsion of the brachial plexus in human cadavers was demonstrated in our anatomical study.展开更多
Full-azimuth common reflection-angle gathers could be stacked at any azimuth. The stacked data at the azimuth perpendicular to fractures exhibit the largest azimuthal anisotropy, while the stacked data at the azimuth ...Full-azimuth common reflection-angle gathers could be stacked at any azimuth. The stacked data at the azimuth perpendicular to fractures exhibit the largest azimuthal anisotropy, while the stacked data at the azimuth parallel to fractures exhibit the smallest azimuthal anisotropy. In petroleum exploration in Block A, a neritic province in the Bohai Bay, we use the stacked data at the azimuth perpendicular to fractures to improve fault interpretation. We also use attribute fusion to identify fractures in different directions.展开更多
Objective:To assess the performance and advantages of HyperArc for radiotherapy of multiple brain metastases with dosimetric parameters with respect to coplanar volumetric modulated arc radiotherapy(c-VMAT),and charac...Objective:To assess the performance and advantages of HyperArc for radiotherapy of multiple brain metastases with dosimetric parameters with respect to coplanar volumetric modulated arc radiotherapy(c-VMAT),and characterize implicit correlations between tumor features and dosimetric parameters.Methods:This retrospective study involved 40 patients with multiple brain metastases(4–16 tumors,12.8–240.8 cm3)who received simultaneous radiotherapy at the Department of Radiation Oncology,Shenzhen People's Hospital from January 2019 to December 2022.Both HyperArc and c-VMAT plans were designed by the same and qualified physicist using the Eclipse system with Truebeam.A single isocenter and a 6 MV flattening filter-free(6FFF)photon beam were used for radiotherapy of multiple brain metastases in each plan.Dosimetric parameters of tumors and organs at risk(OARs)were compared between HyperArc and c-VMAT plans.Corre-lations between tumor features(number and volume)and dosimetric parameters were revealed and analyzed.Furthermore,monitor units(MUs)of both plan types were recorded to assess rays utilization and delivery efficiency.Results:Compared to c-VMAT plans,HyperArc plans achieved higher maximum dose(D_(max))(5.23%,t=7.87,P<0.01),but lower minimum dose(Dmin)(3.94%,t=-2.12,P=0.04)and mean dose(D_(mean))(1.05%,t=-3.29,P<0.01)for planning gross tumor volumes(PGTVs).The conformity index(CI),homogeneity index(HI),gradient index(GI)and R50%of PGTVs with HyperArc were better than those with c-VMAT,with the improve-ments of 20.78%,1.68%,19.83%and 36.20%,respectively(P<0.01).The dosimetric parameters of OARs were significantly improved in HyperArc plans compared to c-VMAT plans.Specifically,the D_(max)and the D_(mean)to the brainstem decreased by 16.14%and 11.37%,respectively.The D_(max)for eye_L decreased by 16.88%,for eye_R decreased by 11.67%,for optical nerve_L decreased by 12.56%,and for chiasm decreased by 18.12%.Few correlations were observed between the differences of CI/HI/GI/R50%and the number of PGTVs between the two plan types.Whereas,regression analysis indicated that the differences of CI/GI/R50%were negatively correlated with the volume of PGTVs,respectively.Moreover,although HyperArc plans reduced the MUs by 4.74%compared to c-VMAT,no significant difference was observed(P>0.05).Conclusions:This study demonstrates the promising performance of HyperArc for radiotherapy of multiple brain metastases,including better dose conformity for the tumors,more rapid dose drop and less dose spillage outside the tumors area,effective reduction of dose bridges among close tumors,and sparing OARs.It also reveals the correlations between the number or volume of tumors and dose parameters,which can help optimize the use of HyperArc and predict clinical benefits.展开更多
The fission yield data in the 14 MeV energy neutron induced fission of^(238)U play an important role in decay heat calculations and generation-Ⅳ reactor designs.In order to accurately measure fission product yields(F...The fission yield data in the 14 MeV energy neutron induced fission of^(238)U play an important role in decay heat calculations and generation-Ⅳ reactor designs.In order to accurately measure fission product yields(FPYs)of^(238)U induced by 14 MeV neutrons,the cumulative yields of fission products ranging from^(92)Sr to^(147)Nd in the^(239)U(n,f) reaction with a 14.7 MeV neutron were determined using an off-line γ-ray spectrometric technique.The14.7 MeV quasi-monoenergetic neutron beam was provided by the K-400 D-T neutron generator at China Academy of Engineering Physics(CAEP).Fission products were measured by a low background high purity germanium gamma spectrometer.The neutron flux was obtained from the^(93)Nb(n.2n)^(92m)Nb reaction,and the mean neutron energy was calculated using the cross-section ratios for the^(90)Zr(n,2n)^(89)Zr and^(93)Nb(n,2n)^(92m)Nb reactions.With a series of corrections,high precision cumulative yields of 20 fission products were obtained.Our FPYs for the^(238)U(n,f) reaction at 14.7 MeV were compared with the existing experimental nuclear reaction data and evaluated nuclear data,respectively.The results will be helpful in the design of a generation-Ⅳ reactor and the construction of evaluated fission yield databases.展开更多
This paper is concerned with the superconvergent points of the continuous Galerkin solutions for delay differential equations of pantograph type. We prove the local nodal superconvergence of continuous Galerkin soluti...This paper is concerned with the superconvergent points of the continuous Galerkin solutions for delay differential equations of pantograph type. We prove the local nodal superconvergence of continuous Galerkin solutions under uniform meshes and locate all the superconvergent points based on the supercloseness between the continuous Galerkin solution U and the interpolation Hhu of the exact solution u. The theoretical results are illustrated by numerical examples.展开更多
Heterostructured(HS)material with extraordinary mechanical properties has been regarded as one of the most promising structural materials.Here,we reported a new strategy for preparing heterostructured pure titanium la...Heterostructured(HS)material with extraordinary mechanical properties has been regarded as one of the most promising structural materials.Here,we reported a new strategy for preparing heterostructured pure titanium laminates that possess a good combination of strength and ductility by combining gradient structure(GS)and heterogeneous lamella structure(HLS).The deformation characteristic versus microstructure evolution of GS/HLS titanium laminates,namely the strain partitions between different-sized grains(480–25μm)was visualized using a scanning electron microscope(SEM)equipped with electron backscattered diffraction(EBSD)mode combined with the digital image correlation(SEM-DIC)with an ultrahigh spatial resolution for the first time.As a result,the hetero-deformation of unique GS/HLS structure by the characteristic of strain partitions could be accurately captured.While the hetero-deformation could result in the hetero-deformation induced(HDI)stress strengthening and HDI hardening,which were regarded as the key reason that the resulting GS/HLS Ti laminates showed a superior combination of strength and ductility.This could promote a more in-depth understanding of the strengtheningtoughening mechanism of heterostructured material.展开更多
In this study, shear tests have been performed on the as-reflowed Sn3.5Ag solder bumps and joints to investigate the deformation behavior of Sn3.5Ag lead-free solder samples. Scanning electron microscopy (SEM) was e...In this study, shear tests have been performed on the as-reflowed Sn3.5Ag solder bumps and joints to investigate the deformation behavior of Sn3.5Ag lead-free solder samples. Scanning electron microscopy (SEM) was employed to characterize the microstructures of the samples and orientation imaging microscopy (OIM) with electron backscattered diffraction (EBSD) in SEM was used to obtain crystallographic orientation of grains to provide a detailed characterization of the deformation behavior in Sn3.5Ag solder samples after shear tests. The deformation behavior in solder samples under shear stress was discussed. The experimental results suggest that the dynamic recrystallization could occur under shear stress at room temperature and recrystallized grains should evolve from subgrains by rotation. Compared with that of non-recrystallized and as-reflowed microstructures, the microhardness of the recrystallized microstructure decreased after shear tests.展开更多
A small Pb-free solder joint exhibits an extremely strong anisotropy due to the body- centered tetragonal (BCT) lattice structure of β-Sn. Grain orientations can signif- icantly influence the failure mode of Pb-fre...A small Pb-free solder joint exhibits an extremely strong anisotropy due to the body- centered tetragonal (BCT) lattice structure of β-Sn. Grain orientations can signif- icantly influence the failure mode of Pb-free solder joints under thermomechanical fatigue (TMF) due to the coefficient of thermal expansion (CTE) mismatch of β-Sn grains. The research work in this paper focused on the microstructure and damage evolution of Sn3.0Ag0.5Cu BGA packages as well as individual Sn3.5Ag solder joints without constraints introduced by the package structure under TMF tests. The mi- crostructure and damage evolution in cross-sections of solder joints under thermome- chanical shock tests were Characterized using optical microscopy with cross-polarized light and scanning electron microscopy (SEM), and orientations of Sn grains were determined by orientation imaging microscopy (OIM). During TMF, obvious recrys- tallization regions were observed with different thermomechanical responses depend- ing on Sn grain orientations. It indicates that substantial stresses can build up at grain boundaries, leading to significant grain boundary sliding. The results show that recrystallized grains prefer to nucleate along pre-existing high-angle grain boundaries and fatigue cracks tend to propagate intergranularly in recrystallized regions, leading to an accelerated damage after recrystallization .展开更多
To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low alloy steel for serv...To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low alloy steel for service performance,four multistage machining processes were applied to the 45Cr Ni Mo VA steel,including the Rough Turning process(RT),RT+the Finish Turning process(FRT),FRT+the Grinding process(GFRT)and RT+the Finish Turning process on dry cutting condition(FRT0).The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50%when it evolved from the RT process.The lower surface roughness of R1.3μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density,and the crack feature evolved from some specific bulges to flat shear plane characteristics.When the GFRT process evolved from the FRT process,its average fatigue life increased by 1.45 times,compared with the RT process.Plastic strain amplitude decreased by 21%,and the strain energy density decreased by 4%due to more considerable compressive residual stress(-249 MPa).Plastic deformation layer depth had a consistent tendency with surface roughness.In this paper,surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained.A fatigue life prediction model based on the energy method for machined surface integrity is proposed.展开更多
Background and aims:Although some studies have identified a possible link between the De Ritis ratio and the mortality of patients with COVID-19),the predictive value and the optimal cut-value remain unclear.This stud...Background and aims:Although some studies have identified a possible link between the De Ritis ratio and the mortality of patients with COVID-19),the predictive value and the optimal cut-value remain unclear.This study aimed to explore the correlation between the De Ritis ratio and mortality in hospitalized COVID-19.Methods:The data for this cohort study came from a retrospective cohort study that was carried out in a medical system in New York City.The primary outcome was the in-hospital mortality of included patients.The researchers ran multivariate Cox regression analyses,curve fitting,and subgroup analysis to support our findings.Overall survival in different De Ritis ratio groups was plotted as Kaplan-Meier survival curves.Results:The study enrolled 4371 participants with COVID-19 from March 1,2020 to April 16,2020.The overall mortality was 24.8%(1082/4371).The curve fitting analyses indicated that the De Ritis ratio has a positive linear connection with mortality in patients with COVID-19.After adjusting for all covariates,participants with a De Ritis ratio≥2 exhibited 1.29 times the risk of in-hospital mortality compared with those with a De Ritis ratio<1(hazard ratio 1.29,95%confidence interval 1.02-1.62,p=0.031).The p for trend was<0.05 for all models.Patients in the group with a De Ritis ratio≥2 experienced the shortest survival time in the Kaplan-Meier survival analysis.Conclusions:A higher baseline De Ritis ratio is correlated with a corresponding higher mortality among hospitalized people with COVID-19.展开更多
基金supported by the National Natural Science Foundation of China,No.82272484(to XC).
文摘The inflammatory microenvironment and neurotoxicity can hinder neuronal regeneration and functional recovery after spinal cord injury.Ruxolitinib,a JAK-STAT inhibitor,exhibits effectiveness in autoimmune diseases,arthritis,and managing inflammatory cytokine storms.Although studies have shown the neuroprotective potential of ruxolitinib in neurological trauma,the exact mechanism by which it enhances functional recovery after spinal cord injury,particularly its effect on astrocytes,remains unclear.To address this gap,we established a mouse model of T10 spinal cord contusion and found that ruxolitinib effectively improved hindlimb motor function and reduced the area of spinal cord injury.Transcriptome sequencing analysis showed that ruxolitinib alleviated inflammation and immune response after spinal cord injury,restored EAAT2 expression,reduced glutamate levels,and alleviated excitatory toxicity.Furthermore,ruxolitinib inhibited the phosphorylation of JAK2 and STAT3 in the injured spinal cord and decreased the phosphorylation level of nuclear factor kappa-B and the expression of inflammatory factors interleukin-1β,interleukin-6,and tumor necrosis factor-α.Additionally,in glutamate-induced excitotoxicity astrocytes,ruxolitinib restored EAAT2 expression and increased glutamate uptake by inhibiting the activation of STAT3,thereby reducing glutamate-induced neurotoxicity,calcium influx,oxidative stress,and cell apoptosis,and increasing the complexity of dendritic branching.Collectively,these results indicate that ruxolitinib restores glutamate homeostasis by rescuing the expression of EAAT2 in astrocytes,reduces neurotoxicity,and effectively alleviates inflammatory and immune responses after spinal cord injury,thereby promoting functional recovery after spinal cord injury.
基金supported by the National Natural Science Foundation of China (Grant #81371968, #81371969,#81401791)the Program for Development of Innovative Research Team in the First Affiliated Hospital of NJMU (No. IRT-015)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This study was aimed to introduce a novel entry point for pedicle screw fixation in the thoracic spine and compare it with the traditional entry point. A novel entry point was found with the aim of improving accuracy, safety and stability of pedicle screw technique based on anatomical structures of the spine. A total of 76 pieces of normal thoracic CT images at the transverse plane and the thoracic pedicle anatomy of 6 cadaveric specimens were recruited.Transverse pedicle angle(TPA), screw length, screw placement accuracy rate and axial pullout strength of the two different entry point groups were compared. There were significant differences in the TPA, screw length, and the screw placement accuracy rate between the two groups(P〈0.05). The maximum axial pullout strength of the novel entry point group was slightly larger than that of the traditional group. However, the difference was not significant(P 〉 0.05). The novel entry point significantly improved the accuracy, stability and safety of pedicle screw placement.With reference to the advantages above, the new entry point can be used for spinal internal fixations in the thoracic spine.
文摘The influence of thermal cycling on the microstructure and joint strength of Sn3.5Ag0.75Cu (SAC) and Sn63Pb37 (SnPb) solder joints was investigated. SAC and SnPb solder balls were soldered on 0.1 and 0.9 μm Au finished metallization, respectively. After 1000 thermal cycles between -40℃ and 125℃, a very thin intermetallic compound (IMC) layer containing Au, Sn, Ni, and Cu formed at the interface between SAC solder joints and underneath metallization with 0.1 μm Au finish, and (Au, Ni, Cu)Sn4 and a very thin AuSn-Ni-Cu IMC layer formed between SAC solder joints and underneath metallization with 0.9 μm Au finish. For SnPb solder joints with 0.1 μm Au finish, a thin (Ni, Cu, Au)3Sn4 IMC layer and a Pb-rich layer formed below and above the (Au, Ni)Sn4 IMC, respectively. Cu diffused through Ni layer and was involved into the IMC formation process. Similar interfacial microstructure was also found for SnPb solder joints with 0.9μm Au finish. The results of shear test show that the shear strength of SAC solder joints is consistently higher than that of SnPb eutectic solder joints during thermal cycling.
基金supported by the National NaturalScience Foundation of China(Grant#81401791,#81371968,#81672152)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The study aimed to demonstrate the feasibility of an extradural nerve anastomosis technique for the restoration of a C5 and C6 avulsion of the brachial plexus.Nine fresh frozen human cadavers were used.The diameters,sizes,and locations of the extradural spinal nerve roots were observed.The lengths of the extradural spinal nerve roots and the distance between the neighboring nerve root outlets were measured and compared in the cervical segments.In the spinal canal,the ventral and dorsal roots were separated by the dura and arachnoid.The ventral and dorsal roots of C7 had sufficient lengths to anastomose those of C6.The ventral and dorsal of C4 had enough length to be transferred to those of C5,respectively.The feasibility of this extradural nerve anastomosis technique for restoring C5 and C6 avulsion of the brachial plexus in human cadavers was demonstrated in our anatomical study.
文摘Full-azimuth common reflection-angle gathers could be stacked at any azimuth. The stacked data at the azimuth perpendicular to fractures exhibit the largest azimuthal anisotropy, while the stacked data at the azimuth parallel to fractures exhibit the smallest azimuthal anisotropy. In petroleum exploration in Block A, a neritic province in the Bohai Bay, we use the stacked data at the azimuth perpendicular to fractures to improve fault interpretation. We also use attribute fusion to identify fractures in different directions.
文摘Objective:To assess the performance and advantages of HyperArc for radiotherapy of multiple brain metastases with dosimetric parameters with respect to coplanar volumetric modulated arc radiotherapy(c-VMAT),and characterize implicit correlations between tumor features and dosimetric parameters.Methods:This retrospective study involved 40 patients with multiple brain metastases(4–16 tumors,12.8–240.8 cm3)who received simultaneous radiotherapy at the Department of Radiation Oncology,Shenzhen People's Hospital from January 2019 to December 2022.Both HyperArc and c-VMAT plans were designed by the same and qualified physicist using the Eclipse system with Truebeam.A single isocenter and a 6 MV flattening filter-free(6FFF)photon beam were used for radiotherapy of multiple brain metastases in each plan.Dosimetric parameters of tumors and organs at risk(OARs)were compared between HyperArc and c-VMAT plans.Corre-lations between tumor features(number and volume)and dosimetric parameters were revealed and analyzed.Furthermore,monitor units(MUs)of both plan types were recorded to assess rays utilization and delivery efficiency.Results:Compared to c-VMAT plans,HyperArc plans achieved higher maximum dose(D_(max))(5.23%,t=7.87,P<0.01),but lower minimum dose(Dmin)(3.94%,t=-2.12,P=0.04)and mean dose(D_(mean))(1.05%,t=-3.29,P<0.01)for planning gross tumor volumes(PGTVs).The conformity index(CI),homogeneity index(HI),gradient index(GI)and R50%of PGTVs with HyperArc were better than those with c-VMAT,with the improve-ments of 20.78%,1.68%,19.83%and 36.20%,respectively(P<0.01).The dosimetric parameters of OARs were significantly improved in HyperArc plans compared to c-VMAT plans.Specifically,the D_(max)and the D_(mean)to the brainstem decreased by 16.14%and 11.37%,respectively.The D_(max)for eye_L decreased by 16.88%,for eye_R decreased by 11.67%,for optical nerve_L decreased by 12.56%,and for chiasm decreased by 18.12%.Few correlations were observed between the differences of CI/HI/GI/R50%and the number of PGTVs between the two plan types.Whereas,regression analysis indicated that the differences of CI/GI/R50%were negatively correlated with the volume of PGTVs,respectively.Moreover,although HyperArc plans reduced the MUs by 4.74%compared to c-VMAT,no significant difference was observed(P>0.05).Conclusions:This study demonstrates the promising performance of HyperArc for radiotherapy of multiple brain metastases,including better dose conformity for the tumors,more rapid dose drop and less dose spillage outside the tumors area,effective reduction of dose bridges among close tumors,and sparing OARs.It also reveals the correlations between the number or volume of tumors and dose parameters,which can help optimize the use of HyperArc and predict clinical benefits.
基金Supported by the National Natural Science Foundation of China (11975113)。
文摘The fission yield data in the 14 MeV energy neutron induced fission of^(238)U play an important role in decay heat calculations and generation-Ⅳ reactor designs.In order to accurately measure fission product yields(FPYs)of^(238)U induced by 14 MeV neutrons,the cumulative yields of fission products ranging from^(92)Sr to^(147)Nd in the^(239)U(n,f) reaction with a 14.7 MeV neutron were determined using an off-line γ-ray spectrometric technique.The14.7 MeV quasi-monoenergetic neutron beam was provided by the K-400 D-T neutron generator at China Academy of Engineering Physics(CAEP).Fission products were measured by a low background high purity germanium gamma spectrometer.The neutron flux was obtained from the^(93)Nb(n.2n)^(92m)Nb reaction,and the mean neutron energy was calculated using the cross-section ratios for the^(90)Zr(n,2n)^(89)Zr and^(93)Nb(n,2n)^(92m)Nb reactions.With a series of corrections,high precision cumulative yields of 20 fission products were obtained.Our FPYs for the^(238)U(n,f) reaction at 14.7 MeV were compared with the existing experimental nuclear reaction data and evaluated nuclear data,respectively.The results will be helpful in the design of a generation-Ⅳ reactor and the construction of evaluated fission yield databases.
基金Acknowledgments. The second author is supported by NSFC (Nos. 11571027, 91430215), by Beijing Nova Program (No. 2151100003150140) and by the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions (No. CIT&TCD201504012). The third author is supported by the Natural Science Foundation of Fujian Province of China (No.2013J05015), by NSFC (No.11301437), and by the Fundamental Research ~nds for the Central Universities (No. 20720150004).
文摘This paper is concerned with the superconvergent points of the continuous Galerkin solutions for delay differential equations of pantograph type. We prove the local nodal superconvergence of continuous Galerkin solutions under uniform meshes and locate all the superconvergent points based on the supercloseness between the continuous Galerkin solution U and the interpolation Hhu of the exact solution u. The theoretical results are illustrated by numerical examples.
基金financially supported by the National Nature Science Foundation of China(Grant Nos.51771064,51971079,and 51501040)。
文摘Heterostructured(HS)material with extraordinary mechanical properties has been regarded as one of the most promising structural materials.Here,we reported a new strategy for preparing heterostructured pure titanium laminates that possess a good combination of strength and ductility by combining gradient structure(GS)and heterogeneous lamella structure(HLS).The deformation characteristic versus microstructure evolution of GS/HLS titanium laminates,namely the strain partitions between different-sized grains(480–25μm)was visualized using a scanning electron microscope(SEM)equipped with electron backscattered diffraction(EBSD)mode combined with the digital image correlation(SEM-DIC)with an ultrahigh spatial resolution for the first time.As a result,the hetero-deformation of unique GS/HLS structure by the characteristic of strain partitions could be accurately captured.While the hetero-deformation could result in the hetero-deformation induced(HDI)stress strengthening and HDI hardening,which were regarded as the key reason that the resulting GS/HLS Ti laminates showed a superior combination of strength and ductility.This could promote a more in-depth understanding of the strengtheningtoughening mechanism of heterostructured material.
基金supported by the National Natural Science Foundation of China under Grant No.50905042the Shenzhen Special Funds for Overseas High-level Talents(No. KQC201109020053A)+1 种基金Shenzhen Technological Innovation Project (No.CXZZ20120829103358067)the Shenzhen Special Funds for Strategic Emerging Industries(No.JCYJ20120613140542764)
文摘In this study, shear tests have been performed on the as-reflowed Sn3.5Ag solder bumps and joints to investigate the deformation behavior of Sn3.5Ag lead-free solder samples. Scanning electron microscopy (SEM) was employed to characterize the microstructures of the samples and orientation imaging microscopy (OIM) with electron backscattered diffraction (EBSD) in SEM was used to obtain crystallographic orientation of grains to provide a detailed characterization of the deformation behavior in Sn3.5Ag solder samples after shear tests. The deformation behavior in solder samples under shear stress was discussed. The experimental results suggest that the dynamic recrystallization could occur under shear stress at room temperature and recrystallized grains should evolve from subgrains by rotation. Compared with that of non-recrystallized and as-reflowed microstructures, the microhardness of the recrystallized microstructure decreased after shear tests.
基金supported by the National Natural Science Foundation of China(No.50905042)the State Key Lab of Advanced Welding&Joining,Harbin Institute of Technology(AWPT-M12-02)
文摘A small Pb-free solder joint exhibits an extremely strong anisotropy due to the body- centered tetragonal (BCT) lattice structure of β-Sn. Grain orientations can signif- icantly influence the failure mode of Pb-free solder joints under thermomechanical fatigue (TMF) due to the coefficient of thermal expansion (CTE) mismatch of β-Sn grains. The research work in this paper focused on the microstructure and damage evolution of Sn3.0Ag0.5Cu BGA packages as well as individual Sn3.5Ag solder joints without constraints introduced by the package structure under TMF tests. The mi- crostructure and damage evolution in cross-sections of solder joints under thermome- chanical shock tests were Characterized using optical microscopy with cross-polarized light and scanning electron microscopy (SEM), and orientations of Sn grains were determined by orientation imaging microscopy (OIM). During TMF, obvious recrys- tallization regions were observed with different thermomechanical responses depend- ing on Sn grain orientations. It indicates that substantial stresses can build up at grain boundaries, leading to significant grain boundary sliding. The results show that recrystallized grains prefer to nucleate along pre-existing high-angle grain boundaries and fatigue cracks tend to propagate intergranularly in recrystallized regions, leading to an accelerated damage after recrystallization .
基金National Natural Science Foundation of China(No.52075042)。
文摘To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low alloy steel for service performance,four multistage machining processes were applied to the 45Cr Ni Mo VA steel,including the Rough Turning process(RT),RT+the Finish Turning process(FRT),FRT+the Grinding process(GFRT)and RT+the Finish Turning process on dry cutting condition(FRT0).The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50%when it evolved from the RT process.The lower surface roughness of R1.3μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density,and the crack feature evolved from some specific bulges to flat shear plane characteristics.When the GFRT process evolved from the FRT process,its average fatigue life increased by 1.45 times,compared with the RT process.Plastic strain amplitude decreased by 21%,and the strain energy density decreased by 4%due to more considerable compressive residual stress(-249 MPa).Plastic deformation layer depth had a consistent tendency with surface roughness.In this paper,surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained.A fatigue life prediction model based on the energy method for machined surface integrity is proposed.
基金supported by the National Natural Science Foundation of China(No.31972719)the Shenzhen Municipal Health Commission project(No.SZXJ2018018).
文摘Background and aims:Although some studies have identified a possible link between the De Ritis ratio and the mortality of patients with COVID-19),the predictive value and the optimal cut-value remain unclear.This study aimed to explore the correlation between the De Ritis ratio and mortality in hospitalized COVID-19.Methods:The data for this cohort study came from a retrospective cohort study that was carried out in a medical system in New York City.The primary outcome was the in-hospital mortality of included patients.The researchers ran multivariate Cox regression analyses,curve fitting,and subgroup analysis to support our findings.Overall survival in different De Ritis ratio groups was plotted as Kaplan-Meier survival curves.Results:The study enrolled 4371 participants with COVID-19 from March 1,2020 to April 16,2020.The overall mortality was 24.8%(1082/4371).The curve fitting analyses indicated that the De Ritis ratio has a positive linear connection with mortality in patients with COVID-19.After adjusting for all covariates,participants with a De Ritis ratio≥2 exhibited 1.29 times the risk of in-hospital mortality compared with those with a De Ritis ratio<1(hazard ratio 1.29,95%confidence interval 1.02-1.62,p=0.031).The p for trend was<0.05 for all models.Patients in the group with a De Ritis ratio≥2 experienced the shortest survival time in the Kaplan-Meier survival analysis.Conclusions:A higher baseline De Ritis ratio is correlated with a corresponding higher mortality among hospitalized people with COVID-19.