The recently demonstrated methods for cooling and trapping diatomic molecules offer new possibilities for precision searches in fundamental physical theories.Here,we propose to study the variations of the fine-structu...The recently demonstrated methods for cooling and trapping diatomic molecules offer new possibilities for precision searches in fundamental physical theories.Here,we propose to study the variations of the fine-structure constant(α=e^(2)/(hc)) and the proton-to-electron mass ratio(μ=m_(p)/m_(e)) with time by taking advantage of the nearly degenerate rovibrational levels in the electronic states of the magnesium fluoride(MgF) molecule.Specifically,due to the cancellation between the fine-structure splitting and the rovibrational intervals in the different MgF natural isotopes,a degeneracy occurs for A^(2)П_(3/2)(v'=0,J'=18.5,-) and A^(2)П_(1/2)(v "=0,J" =20.5,-).We find that using the nearly degenerate energy level of such states can be 104 times more sensitive than using a pure rotational transition to measure the variations of α and μ.To quantify the small gap between A^(2)П_(3/2)(v'=0,J'=18.5,-) and A^(2)П_(1/2)(v "=0,J" =20.5,-),special transitions of choice are feasible:X^(2)Σ_(1/2)~+(v=0,J=19.5,+) to A^(2)П_(3/2)(v'=0,J'=18.5,-) and X^(2)Σ_(1/2)~+(v=0.J=19.5,+)to A^(2)П_(1/2)(v "=0,J" =20.5,-).In addition,we estimate the frequency uncertainties caused by the narrow linewidth,Zeeman shift,Stark shift,Doppler broadening and blackbody radiation.展开更多
The yield ratios of neutron-proton(R(n/p))and^(3)H-^(3)He(R(^(3)H∕^(3)He))with reduced rapidity from 0 to 0.5 were simulated at 50 MeV/u even-even ^(36−56)Ca+^(40)Ca,even-even ^(48−78)Ni+^(58)Ni,and ^(100−139)Sn(ever...The yield ratios of neutron-proton(R(n/p))and^(3)H-^(3)He(R(^(3)H∕^(3)He))with reduced rapidity from 0 to 0.5 were simulated at 50 MeV/u even-even ^(36−56)Ca+^(40)Ca,even-even ^(48−78)Ni+^(58)Ni,and ^(100−139)Sn(every third isotopes)+112 Sn for full reduced impact parameters using the isospin-dependent quantum molecular dynamics(IQMD)model.The neutron and proton density distributions and root-mean-square radii of the reaction systems were obtained using the Skyrme-Hartree-Fock model,which was used for the phase space initialization of the projectile and target in IQMD.We defined the unified neutron skin thickness asΔRnp=<r^(2)>^(1∕2) n−<r^(2)>^(1∕2)p,which was negative for neutron-deficient nuclei.The unifiedΔRnp values for nuclei with the same relative neutron excess from different isotopic chains were nearly equal,except for extreme neutron-rich isotopes,which is a type of scaling behavior.The yield ratios of the three isotopic chain-induced reactions,which depended on the reduced impact parameter and unified neutron skin thickness,were studied.The results showed that both R(n/p)and R(^(3)H∕^(3)He)decreased with a reduced impact parameter for extreme neutron-deficient isotopes;however,they increased with reduced impact parameters for extreme neutron-rich isotopes,and increased with theΔRnp of the projectiles for all reduced impact parameters.In addition,a scaling phenomenon was observed betweenΔR np and the yield ratios in peripheral colli-sions from different isotopic chain projectiles(except for extreme neutron-rich isotopes).Thus,R(n/p)and R(^(3)H∕^(3)He)from peripheral collisions were suggested as experimental probes for extracting the neutron or proton skin thicknesses of non-extreme neutron-rich nuclei from different isotopic chains.展开更多
With the expansion and implementation of rural revitalization strategies,there is a constant need for new energy sources for the construction of new townships.Consequently,integrated energy systems with the interconne...With the expansion and implementation of rural revitalization strategies,there is a constant need for new energy sources for the construction of new townships.Consequently,integrated energy systems with the interconnection and interaction of multiple energy sources are developing rapidly.Biomass energy,a renewable green energy source with low pollution and wide distribution,has significant application potential in integrated energy systems.Considering the application of biomass energy in townships,this study established an integrated biomass energy system and proposed a model to optimize its operation.Lowest economic cost and highest clean energy utilization rate were considered as the objective functions.In addition,a plan was suggested to adjust the heat-electricity ratio based on the characteristics of the combined heat and power of the biomass.Finally,a simulation analysis conducted for a town in China was discussed,demonstrating that the construction of a township integrated-energy system and the use of biomass can significantly reduce operating costs and improve the energy utilization rate.Moreover,by adjusting the heat-electricity ratio,the economic cost was further reduced by 6.70%,whereas the clean energy utilization rate was increased by 5.14%.展开更多
SiC aerogel presents several advantageous features like lightweight and high temperature resistance when applied as microwave absorbing material.In this paper,SiC aerogel was prepared eventually followed by the sol-ge...SiC aerogel presents several advantageous features like lightweight and high temperature resistance when applied as microwave absorbing material.In this paper,SiC aerogel was prepared eventually followed by the sol-gel and carbonization reduction process.The results showed that the effective electromagnetic microwave absorption capacity of SiC aerogel was highly increased after being pyrolyzed at 1500℃,which presented a minimum reflection loss value of-57.80 dB at 3.10 mm and 9.86 GHz.Besides,the electromagnetic parameters of SiC aerogel with different paraffin ratios were discussed as well as the varying electromagnetic microwave absorption performances.The minimum reflection loss value first rose then fell as the SiC/paraffin ratio increased,which demonstrated the importance of SiC content.This study establishes the theoretical foundation for the subsequent functional application of SiC aerogel.展开更多
For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the tur...For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the turnout structure irregularities,and the instability arising from the bridge's flexural deformation lead to a strong coupling effect in the vehicle-turnout-bridge system.This significantly affects both ride comfort and operational safety.For addressing this issue,the present study considered a long-span continuous rigid-frame bridge as an example and established a train-turnout-bridge coupled dynamic model of high-speed railway.Utilizing a selfdeveloped dynamic simulation program,the study analysed the dynamic response characteristics when the train passes through the turnouts on the bridge.It also investigated the influence of different span-to-depth ratios of the bridge on the vehicle dynamic response when the train passes through the main line and branch line of turnouts and then proposed a span-to-depth ratio limit value for a long-span continuous rigid-frame bridge.The research findings suggest that the changes in the span-to-depth ratio have a relatively minor impact on the train’s operational performance but significantly affect the dynamic characteristics of the bridge structure.Based on the findings and a comprehensive assessment of safety indicators,it is advisable to establish a span-to-depth ratio limit of 1/4500 for a long-span continuous rigid-frame bridge.展开更多
This article introduces a method of achieving high polarization extinction ratio using a subwavelength grating structure on a lithium niobate thin film platform,and the chip is formed on the surface of the lithium nio...This article introduces a method of achieving high polarization extinction ratio using a subwavelength grating structure on a lithium niobate thin film platform,and the chip is formed on the surface of the lithium niobate thin film.The chip,with a length of just 20μm,achieved a measured polarization extinction ratio of 29 dB at 1550 nm wavelength.This progress not only proves the possibility of achieving a high extinction ratio on a lithium niobate thin film platform,but also offers important technical references for future work on polarization beam splitters,integrated fiber optic gyroscopes,and so on.展开更多
目的:探讨脊柱手术患者术后切口感染中术前中性粒细胞与淋巴细胞计数比值(neutrophil to lymphocyte ratio,NLR)、血小板与淋巴细胞比值(platelet to lymphocyte ratio,PLR)、C反应蛋白(C-reactive protein,CRP)与白蛋白(albumin,ALB)...目的:探讨脊柱手术患者术后切口感染中术前中性粒细胞与淋巴细胞计数比值(neutrophil to lymphocyte ratio,NLR)、血小板与淋巴细胞比值(platelet to lymphocyte ratio,PLR)、C反应蛋白(C-reactive protein,CRP)与白蛋白(albumin,ALB)比值的临床检测意义。方法:2020年6月至2023年5月行脊柱手术的373例患者,根据术后切口感染情况分为两组,切口感染组65例,男34例,女31例,年龄(56.01±9.78)岁;无切口感染组308例,男157例,女151例,年龄(55.54±10.19)岁。采用血细胞分析仪检测中性粒细胞、淋巴细胞和血小板,计算NLR、PLR;采用免疫比浊法测定血清CRP、ALB水平,计算CRP/ALB比值;采用受试者工作特征(receiver operating characteristic,ROC)曲线分析术前NLR、PLR及CRP/ALB比值对脊柱手术后切口感染的预测价值;采用Logistic多因素回归分析脊柱手术后切口感染的影响因素。结果:切口感染组术前NLR为4.92±1.13、PLR为119.32±22.74、CRP/ALB比值10.19±2.51、手术时间(3.02±0.64)h、糖尿病史(25/65,38.46%)、固定物置入患者比例(21/65,32.31%)均高于无切口感染组的3.72±0.81、90.58±20.16、7.23±2.21、(2.26±0.51)h、(53/308,16.88%)、(36/308,11.69%),差异有统计学意义(P<0.05)。术前NLR、PLR及CRP/ALB比值单独及联合预测脊柱手术后切口感染的AUC分别为0.786、0.806、0.839、0.926。术前NLR、PLR及CRP/ALB比值是脊柱手术后切口感染的独立危险因素(P<0.05)。结论:术前NLR、PLR及CRP/ALB比值测定有利于脊柱手术后切口感染的早期预测,三者联合检测可进一步提高预测结果的准确性。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12174115,11834003,and 91836103)。
文摘The recently demonstrated methods for cooling and trapping diatomic molecules offer new possibilities for precision searches in fundamental physical theories.Here,we propose to study the variations of the fine-structure constant(α=e^(2)/(hc)) and the proton-to-electron mass ratio(μ=m_(p)/m_(e)) with time by taking advantage of the nearly degenerate rovibrational levels in the electronic states of the magnesium fluoride(MgF) molecule.Specifically,due to the cancellation between the fine-structure splitting and the rovibrational intervals in the different MgF natural isotopes,a degeneracy occurs for A^(2)П_(3/2)(v'=0,J'=18.5,-) and A^(2)П_(1/2)(v "=0,J" =20.5,-).We find that using the nearly degenerate energy level of such states can be 104 times more sensitive than using a pure rotational transition to measure the variations of α and μ.To quantify the small gap between A^(2)П_(3/2)(v'=0,J'=18.5,-) and A^(2)П_(1/2)(v "=0,J" =20.5,-),special transitions of choice are feasible:X^(2)Σ_(1/2)~+(v=0,J=19.5,+) to A^(2)П_(3/2)(v'=0,J'=18.5,-) and X^(2)Σ_(1/2)~+(v=0.J=19.5,+)to A^(2)П_(1/2)(v "=0,J" =20.5,-).In addition,we estimate the frequency uncertainties caused by the narrow linewidth,Zeeman shift,Stark shift,Doppler broadening and blackbody radiation.
基金supported by National Natural Science Foundation of China(No.11405025).
文摘The yield ratios of neutron-proton(R(n/p))and^(3)H-^(3)He(R(^(3)H∕^(3)He))with reduced rapidity from 0 to 0.5 were simulated at 50 MeV/u even-even ^(36−56)Ca+^(40)Ca,even-even ^(48−78)Ni+^(58)Ni,and ^(100−139)Sn(every third isotopes)+112 Sn for full reduced impact parameters using the isospin-dependent quantum molecular dynamics(IQMD)model.The neutron and proton density distributions and root-mean-square radii of the reaction systems were obtained using the Skyrme-Hartree-Fock model,which was used for the phase space initialization of the projectile and target in IQMD.We defined the unified neutron skin thickness asΔRnp=<r^(2)>^(1∕2) n−<r^(2)>^(1∕2)p,which was negative for neutron-deficient nuclei.The unifiedΔRnp values for nuclei with the same relative neutron excess from different isotopic chains were nearly equal,except for extreme neutron-rich isotopes,which is a type of scaling behavior.The yield ratios of the three isotopic chain-induced reactions,which depended on the reduced impact parameter and unified neutron skin thickness,were studied.The results showed that both R(n/p)and R(^(3)H∕^(3)He)decreased with a reduced impact parameter for extreme neutron-deficient isotopes;however,they increased with reduced impact parameters for extreme neutron-rich isotopes,and increased with theΔRnp of the projectiles for all reduced impact parameters.In addition,a scaling phenomenon was observed betweenΔR np and the yield ratios in peripheral colli-sions from different isotopic chain projectiles(except for extreme neutron-rich isotopes).Thus,R(n/p)and R(^(3)H∕^(3)He)from peripheral collisions were suggested as experimental probes for extracting the neutron or proton skin thicknesses of non-extreme neutron-rich nuclei from different isotopic chains.
基金supported by the National Natural Science Foundation of China(U2066211)。
文摘With the expansion and implementation of rural revitalization strategies,there is a constant need for new energy sources for the construction of new townships.Consequently,integrated energy systems with the interconnection and interaction of multiple energy sources are developing rapidly.Biomass energy,a renewable green energy source with low pollution and wide distribution,has significant application potential in integrated energy systems.Considering the application of biomass energy in townships,this study established an integrated biomass energy system and proposed a model to optimize its operation.Lowest economic cost and highest clean energy utilization rate were considered as the objective functions.In addition,a plan was suggested to adjust the heat-electricity ratio based on the characteristics of the combined heat and power of the biomass.Finally,a simulation analysis conducted for a town in China was discussed,demonstrating that the construction of a township integrated-energy system and the use of biomass can significantly reduce operating costs and improve the energy utilization rate.Moreover,by adjusting the heat-electricity ratio,the economic cost was further reduced by 6.70%,whereas the clean energy utilization rate was increased by 5.14%.
基金supported by various grants including the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2021A1515111155 and 2022A1515111200)Basic Research Programs of Taicang(Grant Nos.TC2023JC03 and TC2022JC08)+2 种基金Natural Science Foundation of Shaanxi Province(Grant No.2023JC-QN-0380)Nantong Natural Science Foundation(Grant No.JC2023011)Shanghai Central Guidance Fund for Local Science and Technology Development(Grant No.YDZX20233100004009)。
文摘SiC aerogel presents several advantageous features like lightweight and high temperature resistance when applied as microwave absorbing material.In this paper,SiC aerogel was prepared eventually followed by the sol-gel and carbonization reduction process.The results showed that the effective electromagnetic microwave absorption capacity of SiC aerogel was highly increased after being pyrolyzed at 1500℃,which presented a minimum reflection loss value of-57.80 dB at 3.10 mm and 9.86 GHz.Besides,the electromagnetic parameters of SiC aerogel with different paraffin ratios were discussed as well as the varying electromagnetic microwave absorption performances.The minimum reflection loss value first rose then fell as the SiC/paraffin ratio increased,which demonstrated the importance of SiC content.This study establishes the theoretical foundation for the subsequent functional application of SiC aerogel.
基金supported by the National Key R&D Program of China(2022YFB2602900)the 111 Project(B20040)the China Railway Science and Technology Research and Development Program Project(N2023T011-A(JB)).
文摘For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the turnout structure irregularities,and the instability arising from the bridge's flexural deformation lead to a strong coupling effect in the vehicle-turnout-bridge system.This significantly affects both ride comfort and operational safety.For addressing this issue,the present study considered a long-span continuous rigid-frame bridge as an example and established a train-turnout-bridge coupled dynamic model of high-speed railway.Utilizing a selfdeveloped dynamic simulation program,the study analysed the dynamic response characteristics when the train passes through the turnouts on the bridge.It also investigated the influence of different span-to-depth ratios of the bridge on the vehicle dynamic response when the train passes through the main line and branch line of turnouts and then proposed a span-to-depth ratio limit value for a long-span continuous rigid-frame bridge.The research findings suggest that the changes in the span-to-depth ratio have a relatively minor impact on the train’s operational performance but significantly affect the dynamic characteristics of the bridge structure.Based on the findings and a comprehensive assessment of safety indicators,it is advisable to establish a span-to-depth ratio limit of 1/4500 for a long-span continuous rigid-frame bridge.
基金Supported by Beijing Natural Science Foundation(4242062)and the Youth Innovation Promotion Association,CAS(2021108)。
文摘This article introduces a method of achieving high polarization extinction ratio using a subwavelength grating structure on a lithium niobate thin film platform,and the chip is formed on the surface of the lithium niobate thin film.The chip,with a length of just 20μm,achieved a measured polarization extinction ratio of 29 dB at 1550 nm wavelength.This progress not only proves the possibility of achieving a high extinction ratio on a lithium niobate thin film platform,but also offers important technical references for future work on polarization beam splitters,integrated fiber optic gyroscopes,and so on.
文摘目的:探讨脊柱手术患者术后切口感染中术前中性粒细胞与淋巴细胞计数比值(neutrophil to lymphocyte ratio,NLR)、血小板与淋巴细胞比值(platelet to lymphocyte ratio,PLR)、C反应蛋白(C-reactive protein,CRP)与白蛋白(albumin,ALB)比值的临床检测意义。方法:2020年6月至2023年5月行脊柱手术的373例患者,根据术后切口感染情况分为两组,切口感染组65例,男34例,女31例,年龄(56.01±9.78)岁;无切口感染组308例,男157例,女151例,年龄(55.54±10.19)岁。采用血细胞分析仪检测中性粒细胞、淋巴细胞和血小板,计算NLR、PLR;采用免疫比浊法测定血清CRP、ALB水平,计算CRP/ALB比值;采用受试者工作特征(receiver operating characteristic,ROC)曲线分析术前NLR、PLR及CRP/ALB比值对脊柱手术后切口感染的预测价值;采用Logistic多因素回归分析脊柱手术后切口感染的影响因素。结果:切口感染组术前NLR为4.92±1.13、PLR为119.32±22.74、CRP/ALB比值10.19±2.51、手术时间(3.02±0.64)h、糖尿病史(25/65,38.46%)、固定物置入患者比例(21/65,32.31%)均高于无切口感染组的3.72±0.81、90.58±20.16、7.23±2.21、(2.26±0.51)h、(53/308,16.88%)、(36/308,11.69%),差异有统计学意义(P<0.05)。术前NLR、PLR及CRP/ALB比值单独及联合预测脊柱手术后切口感染的AUC分别为0.786、0.806、0.839、0.926。术前NLR、PLR及CRP/ALB比值是脊柱手术后切口感染的独立危险因素(P<0.05)。结论:术前NLR、PLR及CRP/ALB比值测定有利于脊柱手术后切口感染的早期预测,三者联合检测可进一步提高预测结果的准确性。
