We report a study on the electronic structure and chemical bonding of the PB and AsB diatomic molecules using high-resolution photoelectron imaging of cryogenically-cooled PB^(−)and AsB^(−)anions.The electron affiniti...We report a study on the electronic structure and chemical bonding of the PB and AsB diatomic molecules using high-resolution photoelectron imaging of cryogenically-cooled PB^(−)and AsB^(−)anions.The electron affinities of PB and AsB are measured to be 2.751(1)and 2.600(1)eV,respectively.The ground states of the PB^(−)and AsB−anions are determined to be ^(2)Σ^(+) with a σ^(1)π^(4) valence electron configuration.The ground states of neutral PB and AsB are found to be ^(3)Π_(2) with a σ^(1)π^(3) electron configuration.The spin-orbit excited states(^(3)Π_(1) and ^(3)Π_(0)),as well as two low-lying singlet excited states(^(1)Σ^(+)and ^(1)Π),are observed.Unusual spectroscopic characteristics are observed in the ^(3)Π_(2) ground state of AsB,probably due to state mixing with a higher-lying ^(1)Δ_(2) state.The current work provides extensive electronic and spectroscopic information for the PB and AsB molecules.展开更多
Objective The middle turbinate axilla(MTA)is a crucial anatomical landmark for localizing the lacrimal sac(LS)during endonasal dacryocystorhinostomy(En-DCR).Despite being a standard surgical procedure,En-DCR may lead ...Objective The middle turbinate axilla(MTA)is a crucial anatomical landmark for localizing the lacrimal sac(LS)during endonasal dacryocystorhinostomy(En-DCR).Despite being a standard surgical procedure,En-DCR may lead to severe complications,such as cerebrospinal fluid(CSF)leakage,which is closely associated with anatomical variations between the LS and the anterior skull base(ASB).This study aimed to investigate the anatomical location of the LS relative to the MTA and ASB in Chinese patients with nasolacrimal duct obstruction(NLDO)and analyze the influencing factors.Methods This cross-sectional study enrolled 227 Chinese patients who were diagnosed with NLDO and underwent computed tomographic dacryocystography(CT-DCG).Anatomical distances between LS and MTA,as well as LS and ASB,were measured using CT-DCG images.Results The mean distances from the superior and inferior edges of the LS to the MTA were 9.94±4.70 mm and−0.23±4.15 mm,respectively.Male patients showed significantly more superior–anterior displacement of the LS compared to female patients(P<0.001),while patients with chronic dacryocystitis(CD)had an inferior and posterior LS position relative to those with simple NLDO(P=0.005,P=0.001).The mean distance from the intersection(Point P)of the superior and posterior boundaries of the LS to the ASB(MP)was 18.35±4.48 mm,which was shorter in females and those with frontal sinus aplasia(P=0.001;P<0.001).A subgroup(28/227,12.3%)with a critical anatomical feature was identified,where the distance from Point Q(10 mm posterior to P)to the ASB(NQ distance)was≤10 mm.This subgroup had a higher prevalence of complete supra-MTA LS positioning(71.4%vs.41.2%,P=0.003).Conclusion Preoperative CT-DCG provides essential anatomical insights into the spatial relationship between the LS and MTA in Chinese patients with NLDO.The LS position varies significantly by gender and disease type,with males showing more superior–anterior and CD patients more inferior–posterior positioning relative to the MTA.Special attention should be paid to patients with frontal sinus aplasia or LS entirely above the MTA to minimize the risk of CSF leakage during En-DCR.展开更多
Investigations made by the authors and collaborators into the microstructural and fracture aspects of adiabatic shear bands （ASBs） of the hardened steels and Ti alloys induced by high speed machining （HSM） are bri...Investigations made by the authors and collaborators into the microstructural and fracture aspects of adiabatic shear bands （ASBs） of the hardened steels and Ti alloys induced by high speed machining （HSM） are briefly reviewed. The principal findings are the following： （a） the microstructure inside the ASBs varies from the band center to the normal chip material, the gradient microstructures are found; （b） the HSM can produce two types of ASBs with increasing in cutting speed, the deformed shear bands formed at lower cutting speed and the transformed shear bands formed at higher cutting speed; （c） the very small equiaxed recrystallized grains are observed in the center of the ASBs, the dynamic recrystallization and phase transformation may occur simultaneously during the formation of the transformed ASBs; （d） The dynamic rotational recrystallization is the origin of the equiaxed grains in the center of the ASBs. A microstructural evolution model in ASBs produced during HSM for the harden steel is proposed; （e） the microstructural pattern of fracture surface is characterised by the elongated dimples. A microcosmic adiabatic shear fracture model during HSM of the hardened steel is built up.展开更多
基金supported by the National Science Foundation (Grant No.CHE-2403841)。
文摘We report a study on the electronic structure and chemical bonding of the PB and AsB diatomic molecules using high-resolution photoelectron imaging of cryogenically-cooled PB^(−)and AsB^(−)anions.The electron affinities of PB and AsB are measured to be 2.751(1)and 2.600(1)eV,respectively.The ground states of the PB^(−)and AsB−anions are determined to be ^(2)Σ^(+) with a σ^(1)π^(4) valence electron configuration.The ground states of neutral PB and AsB are found to be ^(3)Π_(2) with a σ^(1)π^(3) electron configuration.The spin-orbit excited states(^(3)Π_(1) and ^(3)Π_(0)),as well as two low-lying singlet excited states(^(1)Σ^(+)and ^(1)Π),are observed.Unusual spectroscopic characteristics are observed in the ^(3)Π_(2) ground state of AsB,probably due to state mixing with a higher-lying ^(1)Δ_(2) state.The current work provides extensive electronic and spectroscopic information for the PB and AsB molecules.
基金funded by grants from the Natural Science Foundation of Hubei Province(No.2022CFB199)the National Natural Science Foundation of China(No.82271127).
文摘Objective The middle turbinate axilla(MTA)is a crucial anatomical landmark for localizing the lacrimal sac(LS)during endonasal dacryocystorhinostomy(En-DCR).Despite being a standard surgical procedure,En-DCR may lead to severe complications,such as cerebrospinal fluid(CSF)leakage,which is closely associated with anatomical variations between the LS and the anterior skull base(ASB).This study aimed to investigate the anatomical location of the LS relative to the MTA and ASB in Chinese patients with nasolacrimal duct obstruction(NLDO)and analyze the influencing factors.Methods This cross-sectional study enrolled 227 Chinese patients who were diagnosed with NLDO and underwent computed tomographic dacryocystography(CT-DCG).Anatomical distances between LS and MTA,as well as LS and ASB,were measured using CT-DCG images.Results The mean distances from the superior and inferior edges of the LS to the MTA were 9.94±4.70 mm and−0.23±4.15 mm,respectively.Male patients showed significantly more superior–anterior displacement of the LS compared to female patients(P<0.001),while patients with chronic dacryocystitis(CD)had an inferior and posterior LS position relative to those with simple NLDO(P=0.005,P=0.001).The mean distance from the intersection(Point P)of the superior and posterior boundaries of the LS to the ASB(MP)was 18.35±4.48 mm,which was shorter in females and those with frontal sinus aplasia(P=0.001;P<0.001).A subgroup(28/227,12.3%)with a critical anatomical feature was identified,where the distance from Point Q(10 mm posterior to P)to the ASB(NQ distance)was≤10 mm.This subgroup had a higher prevalence of complete supra-MTA LS positioning(71.4%vs.41.2%,P=0.003).Conclusion Preoperative CT-DCG provides essential anatomical insights into the spatial relationship between the LS and MTA in Chinese patients with NLDO.The LS position varies significantly by gender and disease type,with males showing more superior–anterior and CD patients more inferior–posterior positioning relative to the MTA.Special attention should be paid to patients with frontal sinus aplasia or LS entirely above the MTA to minimize the risk of CSF leakage during En-DCR.
基金supported by the National Natural Science Foundation of China(Nos.50875033, 50775018 and 51175063)
文摘Investigations made by the authors and collaborators into the microstructural and fracture aspects of adiabatic shear bands （ASBs） of the hardened steels and Ti alloys induced by high speed machining （HSM） are briefly reviewed. The principal findings are the following： （a） the microstructure inside the ASBs varies from the band center to the normal chip material, the gradient microstructures are found; （b） the HSM can produce two types of ASBs with increasing in cutting speed, the deformed shear bands formed at lower cutting speed and the transformed shear bands formed at higher cutting speed; （c） the very small equiaxed recrystallized grains are observed in the center of the ASBs, the dynamic recrystallization and phase transformation may occur simultaneously during the formation of the transformed ASBs; （d） The dynamic rotational recrystallization is the origin of the equiaxed grains in the center of the ASBs. A microstructural evolution model in ASBs produced during HSM for the harden steel is proposed; （e） the microstructural pattern of fracture surface is characterised by the elongated dimples. A microcosmic adiabatic shear fracture model during HSM of the hardened steel is built up.
