Great potential of underground gas/energy storage in salt caverns seems to be a promising solution to support renewable energy.In the underground storage method,the operating cycle unfortunately may reach up to daily ...Great potential of underground gas/energy storage in salt caverns seems to be a promising solution to support renewable energy.In the underground storage method,the operating cycle unfortunately may reach up to daily or even hourly,which generates complicated pressures on the salt cavern.Furthermore,the mechanical behavior of rock salt may change and present distinct failure characteristics under different stress states,which affects the performance of salt cavern during the time period of full service.To reproduce a similar loading condition on the cavern surrounding rock mass,the cyclic triaxial loading/unloading tests are performed on the rock salt to explore the mechanical transition behavior and failure characteristics under different confinement.Experimental results show that the rock salt samples pre-sent a diffused shear failure band with significant bulges at certain locations in low confining pressure conditions(e.g.5 MPa,10 MPa and 15 MPa),which is closely related to crystal misorientation and grain boundary sliding.Under the elevated confinement(e.g.20 MPa,30 MPa and 40 MPa),the dilation band dominates the failure mechanism,where the large-size halite crystals are crushed to be smaller size and new pores are developing.The failure transition mechanism revealed in the paper provides additional insight into the mechanical performance of salt caverns influenced by complicated stress states.展开更多
Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include ele...Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include elemental filling to regulate the band.However,the influence of the most electronegative fluorine on the CoSb_(3) band remains unclear.We carry out density-functional-theory calculations and show that the valence band maximum gradually shifts downward with the increase of fluorine filling,lastly the valence band maximum converges to the highly degenerated secondary valence bands in fluorine-filled skutterudites.展开更多
Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is a...Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is also found to influence the study of exciton ground state energy and ground state binding energy in Al_(x)Ga_(1−x)As semiconductor spherical quantum dots.The Al_(x)Ga_(1−x)As is considered to be a direct semiconductor at AI concentration below 0.45,and an indirect one at the concentration above 0.45.With regards to the former,the ground state binding energy increases and decreases with AI concentration and eigenfrequency,respectively;however,while the ground state energy increases with AI concentration,it is marginally influenced by eigenfrequency.On the other hand,considering the latter,while the ground state binding energy increases with AI concentration,it decreases with eigenfrequency;nevertheless,the ground state energy increases both with AI concentration and eigenfrequency.Hence,for the better practical performance of the semiconductors,the properties of the excitons are suggested to vary by adjusting AI concentration and eigenfrequency.展开更多
We report structural and electronic properties of Na_(2)Ni_(3)S_(4),a quasi-two-dimensional compound composed of alternating layers of[Ni_(3)S_(4)]^(2-)and Na^(+).The compound features a remarkable Ni-based kagome lat...We report structural and electronic properties of Na_(2)Ni_(3)S_(4),a quasi-two-dimensional compound composed of alternating layers of[Ni_(3)S_(4)]^(2-)and Na^(+).The compound features a remarkable Ni-based kagome lattice with a square planar configuration of four surrounding S atoms for each Ni atom.Magnetization and electrical measurements reveal a weak paramagnetic insulator with a gap of about 0.5 eV.Our band structure calculation highlights a set of topological flat bands of the kagome lattice derived from the rotated dxz-orbital with C_(3)+T symmetry in the presence of crystal-field splitting.展开更多
Ru-based superconductor LaRu_(2)As_(2) has been discovered exhibiting the highest critical temperature of ~ 7.8 K among iron-free transition metal pnictides with the ThCr_(2)Si_(2)-type crystal structure. However, mic...Ru-based superconductor LaRu_(2)As_(2) has been discovered exhibiting the highest critical temperature of ~ 7.8 K among iron-free transition metal pnictides with the ThCr_(2)Si_(2)-type crystal structure. However, microscopic research on this novel superconducting material is still lacking. Here, we utilize scanning tunneling microscopy/spectroscopy to uncover the superconductivity and surface structure of LaRu_(2)As_(2). Two distinct terminating surfaces are identified on the cleaved crystals, namely, the As surface and the La surface. Atomic missing line defects are observed on the La surface. Both surfaces exhibit a superconducting gap of ~ 1.0 me V. By employing quasiparticle interference techniques, we observe standing wave patterns near the line defects on the La atomic plane. These patterns are attributed to quasiparticle scattering from two electron type parabolic bands.展开更多
Materials with kagome lattices have attracted significant research attention due to their nontrivial features in energy bands.We theoretically investigate the evolution of electronic band structures of kagome lattices...Materials with kagome lattices have attracted significant research attention due to their nontrivial features in energy bands.We theoretically investigate the evolution of electronic band structures of kagome lattices in response to uniaxial strain using both a tight-binding model and an antidot model based on a periodic muffin-tin potential.It is found that the Dirac points move with applied strain.Furthermore,the flat band of unstrained kagome lattices is found to develop into a highly anisotropic shape under a stretching strain along y direction,forming a partially flat band with a region dispersionless along ky direction while dispersive along kx direction.Our results shed light on the possibility of engineering the electronic band structures of kagome materials by mechanical strain.展开更多
We investigated the one-dimensional diamond ladder in the momentum lattice platform. By inducing multiple twoand four-photon Bragg scatterings among specific momentum states, we achieved a flat band system based on th...We investigated the one-dimensional diamond ladder in the momentum lattice platform. By inducing multiple twoand four-photon Bragg scatterings among specific momentum states, we achieved a flat band system based on the diamond model, precisely controlling the coupling strength and phase between individual lattice sites. Utilizing two lattice sites couplings, we generated a compact localized state associated with the flat band, which remained localized throughout the entire time evolution. We successfully realized the continuous shift of flat bands by adjusting the corresponding nearest neighbor hopping strength, enabling us to observe the complete localization process. This opens avenues for further exploration of more complex properties within flat-band systems, including investigating the robustness of flat-band localized states in disordered flat-band systems and exploring many-body localization in interacting flat-band systems.展开更多
Amniotic band syndrome is an acquired embryo-fetopathy. It is rare and is characterized by malformations mainly affecting the limbs but also the skull, face and thoraco-abdominal axis. Its etiopathogenesis remains poo...Amniotic band syndrome is an acquired embryo-fetopathy. It is rare and is characterized by malformations mainly affecting the limbs but also the skull, face and thoraco-abdominal axis. Its etiopathogenesis remains poorly understood. Its diagnosis is essentially clinical and is classically based on the existence of signs such as furrows, amputations and pseudosyndactyly. To show the importance of antenatal diagnosis in resource-limited countries, we report the case of two newborns, one premature at 31 weeks and the other at term, in whom amniotic band syndrome was discovered incidentally at birth. It involved an amputation of the right leg for both cases. The premature baby was born in a context of neonatal sepsis and will succumb to the latter while the 2nd case was released from the hospital alive. Imaging examinations to search for probable congenital malformations could only be carried out for the 2nd case and no accessible congenital malformation had been identified. And as management of the disease, only psychological support to the parents was provided for the 2 cases. The antenatal discovery of a case of amniotic band syndrome in countries with low technical capacity such as Burundi should push clinicians to think in time about treatment options.展开更多
Band structure analysis holds significant importance for understanding the optoelectronic characteristics of semiconductor structures and exploring their potential applications in practice. For quantum well structures...Band structure analysis holds significant importance for understanding the optoelectronic characteristics of semiconductor structures and exploring their potential applications in practice. For quantum well structures, the energy of carriers in the well splits into discrete energy levels due to the confinement of barriers in the growth direction. However, the discrete energy levels obtained at a fixed wave vector cannot accurately reflect the actual energy band structure. In this work, the band structure of the type-II quantum wells is reanalyzed. When the wave vectors of the entire Brillouin region(corresponding to the growth direction) are taken into account, the quantized energy levels of the carriers in the well are replaced by subbands with certain energy distributions. This new understanding of the energy bands of low-dimensional structures not only helps us to have a deeper cognition of the structure, but also may overturn many viewpoints in traditional band theories and serve as supplementary to the band theory of low-dimensional systems.展开更多
The seismic performance of rubber concrete-layered periodic foundations are significantly influenced by their design,in which the band gaps play a paramount role.Aiming at providing better designs for these foundation...The seismic performance of rubber concrete-layered periodic foundations are significantly influenced by their design,in which the band gaps play a paramount role.Aiming at providing better designs for these foundations,this study first proposes and validates the analytical formulas to approximate the bounds of the first few band gaps.In addition,the mapping relations linking the frequencies of different band gaps are presented.Furthermore,an optimal design method for these foundations is developed,which is validated through an engineering example.It is demonstrated that ensuring the superstructure’s resonance zones are completely covered by the corresponding periodic foundation’s band gaps can achieve satisfactory vibration attenuation effects,which is a good strategy for the design of rubber concrete layered periodic foundations.展开更多
BACKGROUND Endoscopic rubber band ligation(ERBL)is a nonsurgical technique for the treatment of symptomatic internal hemorrhoids but is limited by recurrence and post-procedural pain.AIM To evaluate satisfaction,long-...BACKGROUND Endoscopic rubber band ligation(ERBL)is a nonsurgical technique for the treatment of symptomatic internal hemorrhoids but is limited by recurrence and post-procedural pain.AIM To evaluate satisfaction,long-term recurrence,and post-procedural pain in managing internal hemorrhoids using a combination of polidocanol foam sclerotherapy and ERBL.METHODS This was a prospective,multicenter,randomized study.A total of 195 consecutive patients diagnosed with grade II-III internal hemorrhoids were enrolled from four tertiary hospitals and randomly divided into a cap-assisted endoscopic polidocanol foam sclerobanding(EFSB)or an ERBL group.All patients were followed-up for 12 months.Symptom-based severity and post-procedural pain were assessed using a hemorrhoid severity score(HSS)and a visual analog scale(VAS).Continuous variables were reported as medians and interquartile range.RESULTS One hundred and ninety-five patients were enrolled,with 98 in the EFSB group.HSS was lower in the EFSB group than in the ERBL group at 8 weeks[4.0(3.0-5.0)vs 5.0(4.0-6.0),P=0.003]and 12-month[2.0(1.0-3.0)vs 3.0(2.0-3.0),P<0.001]of follow-up.The prolapse recurrence rate was lower in the EFSB group at 12 months(11.2%vs 21.6%,P=0.038).Multiple linear regression analysis demonstrated that EFSB treatment[B=-0.915,95%confidence interval(CI):−1.301 to−0.530,P=0.001]and rubber band number(B=0.843,95%CI:0.595-1.092,P<0.001)were negatively and independently associated with the VAS score 24 hours post-procedure.The median VAS was lower in the EFSB group than in the ERBL[2.0(1.0-3.0)vs 3.0(2.0-4.0),P<0.001].CONCLUSION Cap-assisted EFSB provided long-term satisfaction and effective relief from the recurrence of prolapse and pain 24 hours post-procedure.展开更多
Objective: This study aims to explore the differences in cerebrospinal fluid oligoclonal band (CSF-OCB) expression among different age groups in viral encephalitis and its reference value for diagnosis. Methods: Forty...Objective: This study aims to explore the differences in cerebrospinal fluid oligoclonal band (CSF-OCB) expression among different age groups in viral encephalitis and its reference value for diagnosis. Methods: Forty-two patients with viral encephalitis were divided into two groups: 25 adults and 17 children. The presence of oligoclonal bands in the cerebrospinal fluid (CSF) was detected using polyacrylamide gel electrophoresis, and CSF routine analysis was conducted for comparative analysis. Results: The CSF-OCB positivity rate was higher in the adult group (48%) compared with the pediatric group (11.76%), with a statistically significant difference (P Conclusion: 1) The expression of CSF-OCB positivity in patients with viral encephalitis is age-related, with higher positivity rates observed in adults compared to children. 2) Although CSF oligoclonal band detection is not a specific diagnostic marker for viral encephalitis in adults, it still holds certain reference value.展开更多
Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-form...Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-formed fault.Digital image correlation and acoustic emission(AE)techniques were used to monitor the evolution of shear bands at the rock bridge area and microcracking behaviors.The experimental results revealed that the shear stresses corresponding to the peak and sub-peak in the stressdisplacement curve are significantly affected by the normal stress.Strain localization bands emerged at both the tip of joints and the rock bridge,and their extension and interaction near the peak stress caused a surge in the AE hit rate and a significant decrease in the AE b value.Short and curvilinear strain bands were detected at low normal stress,while high normal stress generally led to more microcracking events and longer coplanar cracks at the rock bridge area.Furthermore,an increase in normal stress resulted in a higher AE count rate and more energetic AE events during friction sliding along the shearformed fault.It was observed that the elastic energy released during the crack coalescence at the prepeak stage was much greater than that released during friction sliding at the post-peak stage.More than 75%of AE events were located in the low-frequency band(0e100 kHz),and this proportion continued to rise with increasing normal stress.Moreover,more AE events of low AF value and high RA value were observed in specimens subjected to high normal stress,indicating that greater normal stress led to more microcracks of shear nature.展开更多
The combination of endoscopic ultrasound with endoscopic treatment of type 1 gastric variceal hemorrhage may improve the robustness and generalizability of the findings in future studies.Moreover,the esophageal varice...The combination of endoscopic ultrasound with endoscopic treatment of type 1 gastric variceal hemorrhage may improve the robustness and generalizability of the findings in future studies.Moreover,the esophageal varices should also be included in the evaluation of treatment efficacy in subsequent studies to reach a more convincing conclusion.展开更多
BACKGROUND According to practice guidelines,endoscopic band ligation(EBL)and endoscopic tissue adhesive injection(TAI)are recommended for treating bleeding from esophagogastric varices.However,EBL and TAI are known to...BACKGROUND According to practice guidelines,endoscopic band ligation(EBL)and endoscopic tissue adhesive injection(TAI)are recommended for treating bleeding from esophagogastric varices.However,EBL and TAI are known to cause serious complications,such as hemorrhage from dislodged ligature rings caused by EBL and hemorrhage from operation-related ulcers resulting from TAI.However,the optimal therapy for mild to moderate type 1 gastric variceal hemorrhage(GOV1)has not been determined.Therefore,the aim of this study was to discover an individualized treatment for mild to moderate GOV1.AIM To compare the efficacy,safety and costs of EBL and TAI for the treatment of mild and moderate GOV1.METHODS A clinical analysis of the data retrieved from patients with mild or moderate GOV1 gastric varices who were treated under endoscopy was also conducted.Patients were allocated to an EBL group or an endoscopic TAI group.The differences in the incidence of varicose relief,operative time,operation success rate,mortality rate within 6 wk,rebleeding rate,6-wk operation-related ulcer healing rate,complication rate and average operation cost were compared between the two groups of patients.RESULTS The total effective rate of the two treatments was similar,but the efficacy of EBL(66.7%)was markedly better than that of TAI(39.2%)(P<0.05).The operation success rate in both groups was 100%,and the 6-wk mortality rate in both groups was 0%.The average operative time(26 min)in the EBL group was significantly shorter than that in the TAI group(46 min)(P<0.01).The rate of delayed postoperative rebleeding in the EBL group was significantly lower than that in the TAI group(11.8%vs 45.1%)(P<0.01).At 6 wk after the operation,the healing rate of operation-related ulcers in the EBL group was 80.4%,which was significantly greater than that in the TAI group(35.3%)(P<0.01).The incidence of postoperative complications in the two groups was similar.The average cost and other related economic factors were greater for the EBL than for the TAI(P<0.01).CONCLUSION For mild to moderate GOV1,patients with EBL had a greater one-time varix eradication rate,a greater 6-wk operation-related ulcer healing rate,a lower delayed rebleeding rate and a lower cost than patients with TAI.展开更多
Controlling inner-wall band segregation is one of the difficulties in the production of high-strength antisulfur pipes.Comparative tests were carried out on different casting processes(superheat,mold electromagnetic s...Controlling inner-wall band segregation is one of the difficulties in the production of high-strength antisulfur pipes.Comparative tests were carried out on different casting processes(superheat,mold electromagnetic stirring,end electromagnetic stirring,casting speed and soft reduction)for the smelting of high-strength antisulfur pipes.The microstructures of continuous-casting billets and hot-rolled or tempered pipes were analyzed using a metallographic microscope and scanning electron microscope.The mechanism and evolution law regarding the inner-wall band segregation of high-strength antisulfur pipes were studied,and the influence of different casting processes was explored.展开更多
Objective:To explore the implementation of gastrointestinal endoscopy technology and endoscopic narrow-band imaging(NBI)in the early screening of gastric cancer and to observe and study their application effects.Metho...Objective:To explore the implementation of gastrointestinal endoscopy technology and endoscopic narrow-band imaging(NBI)in the early screening of gastric cancer and to observe and study their application effects.Methods:During the period from March 2023 to August 2023,312 patients who received gastroscopy in the Kunming Guandu District People’s Hospital were selected,and they underwent both conventional gastroscopy and endoscopic NBI,with clinicopathological tissue biopsy serving as the gold standard.The application value for early screening of gastric cancer was observed and analyzed.Results:The scoring data showed that the clarity of gastric mucosal glandular tube structure,microvascular structure clarity,and lesion contour scoring data of conventional gastroscopy were lower than those of the NBI technology(P<0.05).The screening rate of pathological biopsy in 312 patients was 18.59%(58 cases).Conventional gastroscopy showed a screening rate of 11.53%(36 cases),while NBI technology examined a screening rate of 17.63%(55 cases),and the two-by-two comparison of the screening rate data of the three groups was not statistically significant(P>0.05).The sensitivity,specificity,accuracy,positive predictive value,and negative predictive value of conventional gastroscopy appeared to be lower than those of NBI technology(P<0.05).Conclusion:In the early screening of gastric cancer,endoscopic NBI technology can be applied to patients.Compared with conventional gastroscopy,it provides a clearer visualization of the structure of the gastric mucosal glandular structure and microvascular structure,with a certain screening rate.Additionally,its sensitivity,specificity,accuracy,positive predictive value,and negative predictive value are higher,demonstrating outstanding effectiveness.展开更多
随着网络业务流量的增长,通信业务对密集波分复用(DWDM)的性能要求越来越高。为了提高传输效率,传输频谱逐渐向C+L Band传输扩展,Super C Band传输应运而生,但目前与之对应的掺铒光纤放大器(EDFA)相关研究较少。针对这一问题,文章提出...随着网络业务流量的增长,通信业务对密集波分复用(DWDM)的性能要求越来越高。为了提高传输效率,传输频谱逐渐向C+L Band传输扩展,Super C Band传输应运而生,但目前与之对应的掺铒光纤放大器(EDFA)相关研究较少。针对这一问题,文章提出了一种针对Super C Band传输的EDFA结构,基于Giles模型,分析了EDFA在Super C Band的特性,利用多级泵浦机制,设计了一种可以在Super C Band范围内进行放大的EDFA。结果表明,在-9.3 dBm入光时,该EDFA可以实现26 dB的平坦增益,16.7 dBm的输出功率,此时噪声指数小于5 dB,Ripple小于0.1 dB。并且根据需要,在入光处于-15.0~-3.5 dBm范围内时,通过调节泵浦功率与可调衰减器,均能够实现7~26 dB的可调增益。该EDFA可应用于5G传输和数据中心之间光纤通信等场合。展开更多
基金This research was financially supported by the Science and Technology Department of Sichuan Province Project,China(Grant Nos.2022YFSY0007,2021YFH0010)the National Scientific Science Foundation of China(Grant No.U20A20266).
文摘Great potential of underground gas/energy storage in salt caverns seems to be a promising solution to support renewable energy.In the underground storage method,the operating cycle unfortunately may reach up to daily or even hourly,which generates complicated pressures on the salt cavern.Furthermore,the mechanical behavior of rock salt may change and present distinct failure characteristics under different stress states,which affects the performance of salt cavern during the time period of full service.To reproduce a similar loading condition on the cavern surrounding rock mass,the cyclic triaxial loading/unloading tests are performed on the rock salt to explore the mechanical transition behavior and failure characteristics under different confinement.Experimental results show that the rock salt samples pre-sent a diffused shear failure band with significant bulges at certain locations in low confining pressure conditions(e.g.5 MPa,10 MPa and 15 MPa),which is closely related to crystal misorientation and grain boundary sliding.Under the elevated confinement(e.g.20 MPa,30 MPa and 40 MPa),the dilation band dominates the failure mechanism,where the large-size halite crystals are crushed to be smaller size and new pores are developing.The failure transition mechanism revealed in the paper provides additional insight into the mechanical performance of salt caverns influenced by complicated stress states.
基金supported by the National Natural Science Foundation of China (Grant Nos.52171220,92163212,and 92163119)the Research Funding of Wuhan Polytechnic University (Grant No.2022RZ059)the National Innovation and Entrepreneurship Training Program for College Students (Grant No.S202310497202)。
文摘Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include elemental filling to regulate the band.However,the influence of the most electronegative fluorine on the CoSb_(3) band remains unclear.We carry out density-functional-theory calculations and show that the valence band maximum gradually shifts downward with the increase of fluorine filling,lastly the valence band maximum converges to the highly degenerated secondary valence bands in fluorine-filled skutterudites.
基金supported by the National Natural Science Foundation of China(Nos.12164032 and 11964026)the Natural Science Foundation of Inner Mongolia(No.2019MS01010)+3 种基金Scientific Research Projects in Colleges and Universities in Inner Mongolia(No.NJZZ19145)Graduate Science Innovative Research Projects(No.S20210281Z)the Natural Science Foundation of Inner Mongolia(No.2022MS01014)Doctor Research Start-up Fund of Inner Mongolia Minzu University(No.BS625).
文摘Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is also found to influence the study of exciton ground state energy and ground state binding energy in Al_(x)Ga_(1−x)As semiconductor spherical quantum dots.The Al_(x)Ga_(1−x)As is considered to be a direct semiconductor at AI concentration below 0.45,and an indirect one at the concentration above 0.45.With regards to the former,the ground state binding energy increases and decreases with AI concentration and eigenfrequency,respectively;however,while the ground state energy increases with AI concentration,it is marginally influenced by eigenfrequency.On the other hand,considering the latter,while the ground state binding energy increases with AI concentration,it decreases with eigenfrequency;nevertheless,the ground state energy increases both with AI concentration and eigenfrequency.Hence,for the better practical performance of the semiconductors,the properties of the excitons are suggested to vary by adjusting AI concentration and eigenfrequency.
基金supported by the National Natural Science Foundation of China(Grant Nos.12141002 and 12225401)the National Key Research and Development Program of China(Grant No.2021YFA1401902)+1 种基金the CAS Interdisciplinary Innovation Teamthe Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)。
文摘We report structural and electronic properties of Na_(2)Ni_(3)S_(4),a quasi-two-dimensional compound composed of alternating layers of[Ni_(3)S_(4)]^(2-)and Na^(+).The compound features a remarkable Ni-based kagome lattice with a square planar configuration of four surrounding S atoms for each Ni atom.Magnetization and electrical measurements reveal a weak paramagnetic insulator with a gap of about 0.5 eV.Our band structure calculation highlights a set of topological flat bands of the kagome lattice derived from the rotated dxz-orbital with C_(3)+T symmetry in the presence of crystal-field splitting.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62488201 and 52072401)the National Key R&D Program of China(Grant No.2019YFA0308500)+1 种基金the Chinese Academy of Sciences(Grant No.YSBR-003)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘Ru-based superconductor LaRu_(2)As_(2) has been discovered exhibiting the highest critical temperature of ~ 7.8 K among iron-free transition metal pnictides with the ThCr_(2)Si_(2)-type crystal structure. However, microscopic research on this novel superconducting material is still lacking. Here, we utilize scanning tunneling microscopy/spectroscopy to uncover the superconductivity and surface structure of LaRu_(2)As_(2). Two distinct terminating surfaces are identified on the cleaved crystals, namely, the As surface and the La surface. Atomic missing line defects are observed on the La surface. Both surfaces exhibit a superconducting gap of ~ 1.0 me V. By employing quasiparticle interference techniques, we observe standing wave patterns near the line defects on the La atomic plane. These patterns are attributed to quasiparticle scattering from two electron type parabolic bands.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11904261 and 11904259).
文摘Materials with kagome lattices have attracted significant research attention due to their nontrivial features in energy bands.We theoretically investigate the evolution of electronic band structures of kagome lattices in response to uniaxial strain using both a tight-binding model and an antidot model based on a periodic muffin-tin potential.It is found that the Dirac points move with applied strain.Furthermore,the flat band of unstrained kagome lattices is found to develop into a highly anisotropic shape under a stretching strain along y direction,forming a partially flat band with a region dispersionless along ky direction while dispersive along kx direction.Our results shed light on the possibility of engineering the electronic band structures of kagome materials by mechanical strain.
基金Project supported by the National Natural Science Foundation of China (Grant No.12074367)Anhui Initiative in Quantum Information Technologies,the National Key Research and Development Program of China (Grant No.2020YFA0309804)+3 种基金Shanghai Municipal Science and Technology Major Project (Grant No.2019SHZDZX01)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB35020200)Innovation Program for Quantum Science and Technology (Grant No.2021ZD0302002)New Cornerstone Science Foundation。
文摘We investigated the one-dimensional diamond ladder in the momentum lattice platform. By inducing multiple twoand four-photon Bragg scatterings among specific momentum states, we achieved a flat band system based on the diamond model, precisely controlling the coupling strength and phase between individual lattice sites. Utilizing two lattice sites couplings, we generated a compact localized state associated with the flat band, which remained localized throughout the entire time evolution. We successfully realized the continuous shift of flat bands by adjusting the corresponding nearest neighbor hopping strength, enabling us to observe the complete localization process. This opens avenues for further exploration of more complex properties within flat-band systems, including investigating the robustness of flat-band localized states in disordered flat-band systems and exploring many-body localization in interacting flat-band systems.
文摘Amniotic band syndrome is an acquired embryo-fetopathy. It is rare and is characterized by malformations mainly affecting the limbs but also the skull, face and thoraco-abdominal axis. Its etiopathogenesis remains poorly understood. Its diagnosis is essentially clinical and is classically based on the existence of signs such as furrows, amputations and pseudosyndactyly. To show the importance of antenatal diagnosis in resource-limited countries, we report the case of two newborns, one premature at 31 weeks and the other at term, in whom amniotic band syndrome was discovered incidentally at birth. It involved an amputation of the right leg for both cases. The premature baby was born in a context of neonatal sepsis and will succumb to the latter while the 2nd case was released from the hospital alive. Imaging examinations to search for probable congenital malformations could only be carried out for the 2nd case and no accessible congenital malformation had been identified. And as management of the disease, only psychological support to the parents was provided for the 2 cases. The antenatal discovery of a case of amniotic band syndrome in countries with low technical capacity such as Burundi should push clinicians to think in time about treatment options.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61991441 and 62004218)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB01000000)Youth Innovation Promotion Association Chinese Academy of Sciences (Grant No. 2021005)。
文摘Band structure analysis holds significant importance for understanding the optoelectronic characteristics of semiconductor structures and exploring their potential applications in practice. For quantum well structures, the energy of carriers in the well splits into discrete energy levels due to the confinement of barriers in the growth direction. However, the discrete energy levels obtained at a fixed wave vector cannot accurately reflect the actual energy band structure. In this work, the band structure of the type-II quantum wells is reanalyzed. When the wave vectors of the entire Brillouin region(corresponding to the growth direction) are taken into account, the quantized energy levels of the carriers in the well are replaced by subbands with certain energy distributions. This new understanding of the energy bands of low-dimensional structures not only helps us to have a deeper cognition of the structure, but also may overturn many viewpoints in traditional band theories and serve as supplementary to the band theory of low-dimensional systems.
基金National Natural Science Foundation of China under Grant Nos.52078395 and 52178301the Open Projects Foundation of the State Key Laboratory for Health and Safety of Bridge Structures under Grant No.BHSKL19-07-GF+1 种基金the Dawn Program of Knowledge Innovation Project from the Bureau of Science and Technology of Wuhan Municipality under Grant No.2022010801020357the Science Research Foundation of Wuhan Institute of Technology under Grant No.K2021030。
文摘The seismic performance of rubber concrete-layered periodic foundations are significantly influenced by their design,in which the band gaps play a paramount role.Aiming at providing better designs for these foundations,this study first proposes and validates the analytical formulas to approximate the bounds of the first few band gaps.In addition,the mapping relations linking the frequencies of different band gaps are presented.Furthermore,an optimal design method for these foundations is developed,which is validated through an engineering example.It is demonstrated that ensuring the superstructure’s resonance zones are completely covered by the corresponding periodic foundation’s band gaps can achieve satisfactory vibration attenuation effects,which is a good strategy for the design of rubber concrete layered periodic foundations.
基金Supported by the Hospital Funded Clinical Research of Xinhua Hospital,No.19XHCR16D.
文摘BACKGROUND Endoscopic rubber band ligation(ERBL)is a nonsurgical technique for the treatment of symptomatic internal hemorrhoids but is limited by recurrence and post-procedural pain.AIM To evaluate satisfaction,long-term recurrence,and post-procedural pain in managing internal hemorrhoids using a combination of polidocanol foam sclerotherapy and ERBL.METHODS This was a prospective,multicenter,randomized study.A total of 195 consecutive patients diagnosed with grade II-III internal hemorrhoids were enrolled from four tertiary hospitals and randomly divided into a cap-assisted endoscopic polidocanol foam sclerobanding(EFSB)or an ERBL group.All patients were followed-up for 12 months.Symptom-based severity and post-procedural pain were assessed using a hemorrhoid severity score(HSS)and a visual analog scale(VAS).Continuous variables were reported as medians and interquartile range.RESULTS One hundred and ninety-five patients were enrolled,with 98 in the EFSB group.HSS was lower in the EFSB group than in the ERBL group at 8 weeks[4.0(3.0-5.0)vs 5.0(4.0-6.0),P=0.003]and 12-month[2.0(1.0-3.0)vs 3.0(2.0-3.0),P<0.001]of follow-up.The prolapse recurrence rate was lower in the EFSB group at 12 months(11.2%vs 21.6%,P=0.038).Multiple linear regression analysis demonstrated that EFSB treatment[B=-0.915,95%confidence interval(CI):−1.301 to−0.530,P=0.001]and rubber band number(B=0.843,95%CI:0.595-1.092,P<0.001)were negatively and independently associated with the VAS score 24 hours post-procedure.The median VAS was lower in the EFSB group than in the ERBL[2.0(1.0-3.0)vs 3.0(2.0-4.0),P<0.001].CONCLUSION Cap-assisted EFSB provided long-term satisfaction and effective relief from the recurrence of prolapse and pain 24 hours post-procedure.
文摘Objective: This study aims to explore the differences in cerebrospinal fluid oligoclonal band (CSF-OCB) expression among different age groups in viral encephalitis and its reference value for diagnosis. Methods: Forty-two patients with viral encephalitis were divided into two groups: 25 adults and 17 children. The presence of oligoclonal bands in the cerebrospinal fluid (CSF) was detected using polyacrylamide gel electrophoresis, and CSF routine analysis was conducted for comparative analysis. Results: The CSF-OCB positivity rate was higher in the adult group (48%) compared with the pediatric group (11.76%), with a statistically significant difference (P Conclusion: 1) The expression of CSF-OCB positivity in patients with viral encephalitis is age-related, with higher positivity rates observed in adults compared to children. 2) Although CSF oligoclonal band detection is not a specific diagnostic marker for viral encephalitis in adults, it still holds certain reference value.
基金supported by the National Natural Science Foundation of China(Grant No.52125903).
文摘Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-formed fault.Digital image correlation and acoustic emission(AE)techniques were used to monitor the evolution of shear bands at the rock bridge area and microcracking behaviors.The experimental results revealed that the shear stresses corresponding to the peak and sub-peak in the stressdisplacement curve are significantly affected by the normal stress.Strain localization bands emerged at both the tip of joints and the rock bridge,and their extension and interaction near the peak stress caused a surge in the AE hit rate and a significant decrease in the AE b value.Short and curvilinear strain bands were detected at low normal stress,while high normal stress generally led to more microcracking events and longer coplanar cracks at the rock bridge area.Furthermore,an increase in normal stress resulted in a higher AE count rate and more energetic AE events during friction sliding along the shearformed fault.It was observed that the elastic energy released during the crack coalescence at the prepeak stage was much greater than that released during friction sliding at the post-peak stage.More than 75%of AE events were located in the low-frequency band(0e100 kHz),and this proportion continued to rise with increasing normal stress.Moreover,more AE events of low AF value and high RA value were observed in specimens subjected to high normal stress,indicating that greater normal stress led to more microcracks of shear nature.
文摘The combination of endoscopic ultrasound with endoscopic treatment of type 1 gastric variceal hemorrhage may improve the robustness and generalizability of the findings in future studies.Moreover,the esophageal varices should also be included in the evaluation of treatment efficacy in subsequent studies to reach a more convincing conclusion.
基金Supported by the Guizhou Provincial Science and Technology Program,No.[2020]4Y004.
文摘BACKGROUND According to practice guidelines,endoscopic band ligation(EBL)and endoscopic tissue adhesive injection(TAI)are recommended for treating bleeding from esophagogastric varices.However,EBL and TAI are known to cause serious complications,such as hemorrhage from dislodged ligature rings caused by EBL and hemorrhage from operation-related ulcers resulting from TAI.However,the optimal therapy for mild to moderate type 1 gastric variceal hemorrhage(GOV1)has not been determined.Therefore,the aim of this study was to discover an individualized treatment for mild to moderate GOV1.AIM To compare the efficacy,safety and costs of EBL and TAI for the treatment of mild and moderate GOV1.METHODS A clinical analysis of the data retrieved from patients with mild or moderate GOV1 gastric varices who were treated under endoscopy was also conducted.Patients were allocated to an EBL group or an endoscopic TAI group.The differences in the incidence of varicose relief,operative time,operation success rate,mortality rate within 6 wk,rebleeding rate,6-wk operation-related ulcer healing rate,complication rate and average operation cost were compared between the two groups of patients.RESULTS The total effective rate of the two treatments was similar,but the efficacy of EBL(66.7%)was markedly better than that of TAI(39.2%)(P<0.05).The operation success rate in both groups was 100%,and the 6-wk mortality rate in both groups was 0%.The average operative time(26 min)in the EBL group was significantly shorter than that in the TAI group(46 min)(P<0.01).The rate of delayed postoperative rebleeding in the EBL group was significantly lower than that in the TAI group(11.8%vs 45.1%)(P<0.01).At 6 wk after the operation,the healing rate of operation-related ulcers in the EBL group was 80.4%,which was significantly greater than that in the TAI group(35.3%)(P<0.01).The incidence of postoperative complications in the two groups was similar.The average cost and other related economic factors were greater for the EBL than for the TAI(P<0.01).CONCLUSION For mild to moderate GOV1,patients with EBL had a greater one-time varix eradication rate,a greater 6-wk operation-related ulcer healing rate,a lower delayed rebleeding rate and a lower cost than patients with TAI.
文摘Controlling inner-wall band segregation is one of the difficulties in the production of high-strength antisulfur pipes.Comparative tests were carried out on different casting processes(superheat,mold electromagnetic stirring,end electromagnetic stirring,casting speed and soft reduction)for the smelting of high-strength antisulfur pipes.The microstructures of continuous-casting billets and hot-rolled or tempered pipes were analyzed using a metallographic microscope and scanning electron microscope.The mechanism and evolution law regarding the inner-wall band segregation of high-strength antisulfur pipes were studied,and the influence of different casting processes was explored.
文摘Objective:To explore the implementation of gastrointestinal endoscopy technology and endoscopic narrow-band imaging(NBI)in the early screening of gastric cancer and to observe and study their application effects.Methods:During the period from March 2023 to August 2023,312 patients who received gastroscopy in the Kunming Guandu District People’s Hospital were selected,and they underwent both conventional gastroscopy and endoscopic NBI,with clinicopathological tissue biopsy serving as the gold standard.The application value for early screening of gastric cancer was observed and analyzed.Results:The scoring data showed that the clarity of gastric mucosal glandular tube structure,microvascular structure clarity,and lesion contour scoring data of conventional gastroscopy were lower than those of the NBI technology(P<0.05).The screening rate of pathological biopsy in 312 patients was 18.59%(58 cases).Conventional gastroscopy showed a screening rate of 11.53%(36 cases),while NBI technology examined a screening rate of 17.63%(55 cases),and the two-by-two comparison of the screening rate data of the three groups was not statistically significant(P>0.05).The sensitivity,specificity,accuracy,positive predictive value,and negative predictive value of conventional gastroscopy appeared to be lower than those of NBI technology(P<0.05).Conclusion:In the early screening of gastric cancer,endoscopic NBI technology can be applied to patients.Compared with conventional gastroscopy,it provides a clearer visualization of the structure of the gastric mucosal glandular structure and microvascular structure,with a certain screening rate.Additionally,its sensitivity,specificity,accuracy,positive predictive value,and negative predictive value are higher,demonstrating outstanding effectiveness.
文摘随着网络业务流量的增长,通信业务对密集波分复用(DWDM)的性能要求越来越高。为了提高传输效率,传输频谱逐渐向C+L Band传输扩展,Super C Band传输应运而生,但目前与之对应的掺铒光纤放大器(EDFA)相关研究较少。针对这一问题,文章提出了一种针对Super C Band传输的EDFA结构,基于Giles模型,分析了EDFA在Super C Band的特性,利用多级泵浦机制,设计了一种可以在Super C Band范围内进行放大的EDFA。结果表明,在-9.3 dBm入光时,该EDFA可以实现26 dB的平坦增益,16.7 dBm的输出功率,此时噪声指数小于5 dB,Ripple小于0.1 dB。并且根据需要,在入光处于-15.0~-3.5 dBm范围内时,通过调节泵浦功率与可调衰减器,均能够实现7~26 dB的可调增益。该EDFA可应用于5G传输和数据中心之间光纤通信等场合。