Betaine combined with traditional Chinese medicine ointment to treat skin wounds in microbially infected diabetic mice

BACKGROUND Skin wounds are highly common in diabetic patients,and with increasing types of pathogenic bacteria and antibiotic resistance,wounds and infections in diabetic patients are difficult to treat and heal.AIM To explore the effects of betaine ointment(BO)in promoting the healing of skin wounds and reducing the inflammation and apoptosis of skin cells in microbially infected diabetic mice.METHODS By detecting the minimum inhibitory concentrations(MICs)of betaine and plant monomer components such as psoralen,we prepared BO with betaine as the main ingredient,blended it with traditional Chinese medicines such as gromwell root and psoralen,and evaluated its antibacterial effects and safety in vitro and in vivo.The skin infection wound models of ordinary mice and diabetic mice were constructed,and the OTC drugs mupirocin ointment and Zicao ointment were used as controls to evaluate the antibacterial effects in vivo and the anti-inflammatory and anti-apoptotic effects of BO.RESULTS The MICs of betaine against microorganisms such as Staphylococcus aureus(S.aureus),Candida albicans and Cryptococcus neoformans ranged from 4 to 32μg/mL.Gromwell root and psoralea,both of which contain antimicrobial components,mixed to prepare BO with MICs ranging from 16 to 64μg/mL,which is 32-256 times lower than those of Zicao ointment,although the MIC is greater than that of betaine.After 15 days of treatment with BO for USA300-infected ordinary mice,the wound scab removal rates were 83.3%,while those of mupirocin ointment and Zicao ointment were 66.7%and 0%,respectively,and the differences were statistically significant.In diabetic mice,the wound scab removal rate of BO and mupirolacin ointment was 80.0%,but BO reduced wound inflammation and the apoptosis of skin cells and facilitated wound healing.CONCLUSION The ointment prepared by mixing betaine and traditional Chinese medicine can effectively inhibit common skin microorganisms and has a strong effect on the skin wounds of sensitive or drug-resistant S.aureus-infected ordinary mice and diabetic mice.

硫酸铜对河川沙塘鳢的急性毒性、肝脏抗氧化酶活性及组织结构的影响

为探究硫酸铜(CuSO_(4))对河川沙塘鳢(Odontobutis potamophila)的急性毒性效应,采用静水生物测试法,根据预试验结果,设定了1.58、2.22、3.16、6.33、12.66和15.82 mg/L共6个浓度梯度进行急性毒性试验,并设定了0.50、0.75、1.00和1.25 mg/L共4个浓度梯度进行急性暴露试验,分别在6、12、24、48、72、96 h时测定肝组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-PX)活性及丙二醛(MDA)含量和肝、鳃组织结构的变化。结果表明:CuSO_(4)对河川沙塘鳢24、48、72和96 h的LC_(50)分别为8.38、3.87、2.92和2.50 mg/L,SC为0.25 mg/L。随着时间的推移和CuSO_(4)浓度的升高,SOD、CAT和GSH-PX活性呈现出先上升后下降的趋势,达峰值时与CK差异显著;MDA含量呈现出先下降后上升的趋势,在最低值和峰值时均与CK差异显著。急性暴露后的河川沙塘鳢肝组织出现空泡化、坏死,细胞核溶解消失,鳃组织出现肿胀变形、坏死脱落。因此,SOD、CAT、GSH-PX活性和MDA含量以及肝、鳃组织结构的变化均反映了河川沙塘鳢机体的受损伤程度,可作为后续河川沙塘鳢养殖试验中用药评价的参考标准。

儒家文化对“招娣/弟”命名偏好的影响:宗族文化之外的新视角

“招娣/弟”命名是独具中国文化特色的现象,体现了家庭和社会对男性后代的偏好。任孝鹏等(2024)的研究以家谱和祠堂分布为宗族文化影响力的代理变量,发现这些因素能预测不同省份“招娣/弟”命名的分布。在此基础上,本研究进一步将孔庙分布作为儒家文化影响的代理指标,探讨了其对“招娣/弟”命名地区差异的作用。结果表明,孔庙分布同样能显著预测该命名现象的区域偏好。通过主成分分析,还发现儒家文化与宗族文化的代理指标虽有交集但并不完全重合。本研究深化了对中国文化因素影响力的理解。

锂氧电池有机电解液的研究进展

随着消费类电子产品和新能源汽车产业的迅速发展,传统的锂离子电池已经不能满足日益增长的能源需求。为了应对这一挑战,许多高比能电池被提出和研发。其中,锂氧电池以其超高的能量密度引起了广泛的关注,但其可逆性较差问题严重限制了锂氧电池的进一步发展。在锂氧电池中,电解液是一个重要的组成部分,其组分和配比对电池的放电容量、倍率性能和负极稳定性等方面具有至关重要的影响。本文以电解液的组分为线索,对锂氧电池有机电解液的发展历程以及最新研究成果进行了梳理和总结。同时,对于降低过电势和抑制电解液分解的展望,也为锂氧电池的未来发展指明了方向。

危机情境下地方政府对旅游业的补贴行为及效果研究

旅游业是一个极其敏感和脆弱的行业,容易受到各种危机事件的影响。因此,在遭遇重大危机时,地方政府往往会采取多种政策来帮助企业渡过危机,然而这些政策对旅游企业和旅游经济的影响尚不明确。为了回答这一问题,文章以公共卫生危机事件为例,调查了不同补贴政策(消费补贴、经营补贴、税收优惠、贷款贴息)的效果,以寻找政府在面临供应链中断风险时的最优补贴模式。结果表明:危机事件对供需双方的影响程度是影响政府补贴额度和补贴政策的重要因素,只有当危机事件对供需两侧的影响满足特定条件时,政府提供的各种补贴才能够通过刺激消费需求来复苏经济;在不同中断场景和有限政府预算下,为实现最大市场消费需求所采取的最佳补贴政策也有所不同,政府应对危机事件影响程度和财政预算进行特定条件评估,并根据评估结果考虑采取“消费补贴”或“税收优惠”或“消费补贴+税收优惠”的补贴方案;对于旅游零售商和旅游供应商来说,无论政府采取哪种补贴方式,其利润均高于无政府补贴的基准情况。以上研究结论可作为政府在公共危机发生时制定补贴政策的理论参考,也可作为旅游公司面对政府财政补贴时进行产品定价的决策依据。

黏弹性表面活性剂芥酰丙基二甲基羧基甜菜碱与水溶性聚丙烯酰胺的溶液拉伸流变行为对比

黏弹性表面活性剂常被称为“活聚合物”或“平衡聚合物”,但其与聚合物溶液在拉伸流变行为方面的异同却鲜见报道。文中利用自行搭建的液珠滴落平板(DoS)拉伸流变仪,对比研究了黏弹性表面活性剂芥酰丙基二甲基羧基甜菜碱(EDAB)与常用的水溶性聚合物——聚丙烯酰胺(PAM)的溶液拉伸流变行为。结果表明,PAM比EDAB溶液中的蠕虫状胶束具有更强的结构柔韧性,因此表现出更高的拉伸黏度和特殊的应变硬化行为。此外,相比于EDAB溶液,PAM溶液的拉伸流变行为对温度更为敏感,因为温度能加速PAM链段的解缠结过程。文中工作可加深对黏弹性表面活性剂在拉伸流场下的溶液行为的理解,为其合理利用提供参考。

ZnO Additive Boosts Charging Speed and Cycling Stability of Electrolytic Zn–Mn Batteries

Electrolytic aqueous zinc-manganese(Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish deposition reaction kinetics of manganese oxide during the charge process and short cycle life. We show that, incorporating ZnO electrolyte additive can form a neutral and highly viscous gel-like electrolyte and render a new form of electrolytic Zn–Mn batteries with significantly improved charging capabilities. Specifically, the ZnO gel-like electrolyte activates the zinc sulfate hydroxide hydrate assisted Mn^(2+) deposition reaction and induces phase and structure change of the deposited manganese oxide(Zn_(2)Mn_(3)O_8·H_(2)O nanorods array), resulting in a significant enhancement of the charge capability and discharge efficiency. The charge capacity increases to 2.5 mAh cm^(-2) after 1 h constant-voltage charging at 2.0 V vs. Zn/Zn^(2+), and the capacity can retain for up to 2000 cycles with negligible attenuation. This research lays the foundation for the advancement of electrolytic Zn–Mn batteries with enhanced charging capability.

TREM-1 mediates interaction between substantia nigra microglia and peripheral neutrophils

Microglia-mediated neuroinflammation is considered a pathological feature of Parkinson's disease.Triggering receptor expressed on myeloid cell-1(TREM-1)can amplify the inherent immune response,and crucially,regulate inflammation.In this study,we found marked elevation of serum soluble TREM-1 in patients with Parkinson's disease that positively correlated with Parkinson's disease severity and dyskinesia.In a mouse model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease,we found that microglial TREM-1 expression also increased in the substantia nigra.Further,TREM-1 knockout alleviated dyskinesia in a mouse model of Parkinson's disease and reduced dopaminergic neuronal injury.Meanwhile,TREM-1 knockout attenuated the neuroinflammatory response,dopaminergic neuronal injury,and neutrophil migration.Next,we established an in vitro 1-methyl-4-phenyl-pyridine-induced BV2 microglia model of Parkinson's disease and treated the cells with the TREM-1 inhibitory peptide LP17.We found that LP17 treatment reduced apoptosis of dopaminergic neurons and neutrophil migration.Moreover,inhibition of neutrophil TREM-1 activation diminished dopaminergic neuronal apoptosis induced by lipopolysaccharide.TREM-1 can activate the downstream CARD9/NF-κB proinflammatory pathway via interaction with SYK.These findings suggest that TREM-1 may play a key role in mediating the damage to dopaminergic neurons in Parkinson's disease by regulating the interaction between microglia and peripheral neutrophils.

Branch-Chain-Rich Diisopropyl Ether with Steric Hindrance Facilitates Stable Cycling of Lithium Batteries at-20℃

Li metal batteries(LMBs)offer signifi-cant potential as high energy density alternatives;nev-ertheless,their performance is hindered by the slow desolvation process of electrolytes,particularly at low temperatures(LT),leading to low coulombic efficiency and limited cycle stability.Thus,it is essential to opti-mize the solvation structure thereby achieving a rapid desolvation process in LMBs at LT.Herein,we introduce branch chain-rich diisopropyl ether(DIPE)into a 2.5 M Li bis(fluorosulfonyl)imide dipropyl ether(DPE)elec-trolyte as a co-solvent for high-performance LMBs at-20℃.The incorporation of DIPE not only enhances the disorder within the electrolyte,but also induces a steric hindrance effect form DIPE’s branch chain,excluding other solvent molecules from Li+solvation sheath.Both of these factors contribute to the weak interactions between Li^(+)and solvent molecules,effectively reducing the desolvation energy of the electrolyte.Consequently,Li(50μm)||LFP(mass loading~10 mg cm^(-2))cells in DPE/DIPE based electrolyte demonstrate stable performance over 650 cycles at-20℃,delivering 87.2 mAh g^(-1),and over 255 cycles at 25℃ with 124.8 mAh g^(-1).DIPE broadens the electrolyte design from molecular structure considera-tions,offering a promising avenue for highly stable LMBs at LT.

Numerical modeling of fracture propagation of supercritical CO_(2)compound fracturing

The exploitation of shale gas is promising due to depletion of the conventional energy and intensification of the greenhouse effect.In this paper,we proposed a heat-fluid-solid coupling damage model of supercritical CO_(2)(SC-CO_(2))compound fracturing which is expected to be an efficient and environmentally friendly way to develop shale gas.The coupling model is solved by the finite element method,and the results are in good agreement with the analytical solutions and fracturing experiments.Based on this model,the fracture propagation characteristics at the two stages of compound fracturing are studied and the influence of pressurization rate,in situ stress,bedding angle,and other factors are considered.The results show that at the SC-CO_(2)fracturing stage,a lower pressurization rate is conducive to formation of the branches around main fractures,while a higher pressurization rate inhibits formation of the branches around main fractures and promotes formation of the main fractures.Both bedding and in situ stress play a dominant role in the fracture propagation.When the in situ stress ratio(δ_(x)/δ_(y))is 1,the presence of bedding can reduce the initiation pressure and failure pressure.Nevertheless,it will cause the fracture to propagate along the bedding direction,reducing the fracture complexity.In rocks without bedding,hydraulic fracturing has the lengthening and widening effects for SC-CO_(2)induced fracture.In shale,fractures induced at the hydraulic fracturing stage are more likely to be dominated by in situ stresses and have a shorter reorientation radius.Therefore,fracture branches propagating along the maximum principal stress direction may be generated around the main fractures induced by SC-CO_(2)at the hydraulic fracturing stage.When the branches converge with the main fractures,fracture zones are easily formed,and thus the fracture complexity and damage area can be significantly increased.The results are instructive for the design and application of SC-CO_(2)compound fracturing.

Lumbar instability remodels cartilage endplate to induce intervertebral disc degeneration by recruiting osteoclasts via Hippo-CCL3 signaling

Degenerated endplate appears with cheese-like morphology and sensory innervation,contributing to low back pain and subsequently inducing intervertebral disc degeneration in the aged population.1 However,the origin and development mechanism of the cheese-like morphology remain unclear.Here in this study,we report lumbar instability induced cartilage endplate remodeling is responsible for this pathological change.

我国保险机构治理质量分析与提升研究——基于2016—2023年中国保险机构治理指数

保险机构良好的公司治理是确保保险业健康和稳健发展的基石。南开大学中国保险机构治理评价课题组(NKU-CIIGET)研发了包含六大治理内容维度和两大治理层次维度共计70个评价指标的中国保险机构治理评价体系(CIIGES),并基于手工整理的保险机构公开披露数据生成了2016—2023年中国保险机构治理指数(CIIGI)。本研究详细论述了中国保险机构治理评价体系的关键评价要素,并基于2016—2023年中国保险机构治理指数,从治理总指数、治理等级和评级、治理分指数以及分类治理指数角度对我国保险机构治理质量展开了全面分析,最后分别从监管层面和机构层面针对性地提出了提升我国保险机构治理质量的对策建议。

Spatiotemporal Variability and Environmental Controls of Temperature Sensitivity of Ecosystem Respiration across the Tibetan Plateau

Warming-induced carbon loss via ecosystem respiration(R_(e))is probably intensifying in the alpine grassland ecosystem of the Tibetan Plateau owing to more accelerated warming and the higher temperature sensitivity of R_(e)(Q_(10)).However,little is known about the patterns and controlling factors of Q_(10)on the plateau,impeding the comprehension of the intensity of terrestrial carbon-climate feedbacks for these sensitive and vulnerable ecosystems.Here,we synthesized and analyzed multiyear observations from 14 sites to systematically compare the spatiotemporal variations of Q_(10)values in diverse climate zones and ecosystems,and further explore the relationships between Q_(10)and environmental factors.Moreover,structural equation modeling was utilized to identify the direct and indirect factors predicting Q_(10)values during the annual,growing,and non-growing seasons.The results indicated that the estimated Q_(10)values were strongly dependent on temperature,generally,with the average Q_(10)during different time periods increasing with air temperature and soil temperature at different measurement depths(5 cm,10 cm,20 cm).The Q_(10)values differentiated among ecosystems and climatic zones,with warming-induced Q_(10)declines being stronger in colder regions than elsewhere based on spatial patterns.NDVI was the most cardinal factor in predicting annual Q_(10)values,significantly and positively correlated with Q_(10).Soil temperature(Ts)was identified as the other powerful predictor for Q_(10),and the negative Q_(10)-Ts relationship demonstrates a larger terrestrial carbon loss potentiality in colder than in warmer regions in response to global warming.Note that the interpretations of the effect of soil moisture on Q_(10)were complicated,reflected in a significant positive relationship between Q_(10)and soil moisture during the growing season and a strong quadratic correlation between the two during the annual and non-growing season.These findings are conducive to improving our understanding of alpine grassland ecosystem carbon-climate feedbacks under warming climates.

Spatial Heterogeneity and Risk Factors of Dental Caries in 12-Year-Old Children in Shanxi Province,China

Objective This study aimed to explore the spatial heterogeneity and risk factors for dental caries in 12-year-old children in Shanxi province,China.Methods The data encompassed 3,721 participants from the two most recent oral health surveys conducted across 16 districts in Shanxi Province in 2015 and 2018.Eighteen specific variables were analyzed to examine the interplay between socioeconomic factors,medical resources and environmental conditions.The Geo-detector model was employed to assess the impacts and interactions of these ecological factors.Results Socioeconomic factors(Q=0.30,P<0.05)exhibited a more substantial impact compared to environmental(Q=0.19,P<0.05)and medical resource factors(Q=0.25,P<0.05).Notably,the urban population percentage(UPP)demonstrated the most significant explanatory power for the spatial heterogeneity in caries prevalence,as denoted by its highest q-value(q=0.51,P<0.05).Additionally,the spatial distribution’s heterogeneity of caries was significantly affected by SO2 concentration(q=0.39,P<0.05)and water fluoride levels(q=0.27,P<0.05)among environmental factors.Conclusion The prevalence of caries exhibited spatial heterogeneity,escalating from North to South in Shanxi Province,China,influenced by socioeconomic factors,medical resources,and environmental conditions to varying extents.

Fractal model of spontaneous imbibition in low-permeability reservoirs coupled with heterogeneity of pore seepage channels and threshold pressure

Spontaneous imbibition(SI)is an important mechanism for enhancing oil recovery in low-permeability reservoirs.Due to the strong heterogeneity,and the non-Darcy flow,the construction of SI model for lowpermeability reservoirs is extremely challenging.Commonly,traditional SI models based on single or averaged capillary tortuosity ignore the influence of heterogeneity of pore seepage channels and the threshold pressure(TP)on imbibition.Therefore,in this work,based on capillary model and fractal theory,a mathematical model of characterizing SI considering heterogeneity of pore seepage channels is established.On this basis,the threshold pressure was introduced to determine the pore radius at which the wetted phase can displace oil.The proposed new SI model was verified by imbibition experimental data.The study shows that for weakly heterogeneous cores with permeability of 0-1 m D,the traditional SI model can characterize the imbibition process relatively accurately,and the new imbibition model can increase the coefficient of determination by 1.05 times.However,traditional model has serious deviations in predicting the imbibition recovery for cores with permeability of 10-50 m D.The new SI model coupling with heterogeneity of pore seepage channels and threshold pressure effectively solves this problem,and the determination coefficient is increased from 0.344 to 0.922,which is increased by2.68 times.For low-permeability reservoirs,the production of the oil in transitional pores(0.01-0.1μm)and mesopores(0.1-1μm)significantly affects the imbibition recovery,as the research shows that when the heterogeneity of pore seepage channels is ignored,the oil recovery in transitional pores and mesopores decreases by 7.54%and 4.26%,respectively.Sensitivity analysis shows that increasing interfacial tension,decreasing contact angle,oil-water viscosity ratio and threshold pressure will increase imbibition recovery.In addition,there are critical values for the influence of these factors on the imbibition recovery,which provides theoretical support for surfactant optimization.

Endorepellin downregulation promotes angiogenesis after experimental traumatic brain injury

Endorepellin plays a key role in the regulation of angiogenesis,but its effects on angiogenesis after traumatic brain injury are unclear.This study explored the effects of endorepellin on angiogenesis and neurobehavioral outcomes after traumatic brain injury in mice.Mice were randomly divided into four groups:sham,controlled cortical impact only,adeno-associated virus(AAV)-green fluorescent protein,and AAV-shEndorepellin-green fluorescent protein groups.In the controlled cortical impact model,the transduction of AAV-shEndorepellin-green fluorescent protein downregulated endorepellin while increasing the number of CD31+/Ki-67+proliferating endothelial cells and the functional microvessel density in mouse brain.These changes resulted in improved neurological function compared with controlled cortical impact mice.Western blotting revealed increased expression of vascular endothelial growth factor and angiopoietin-1 in mice treated with AAV-shEndorepellin-green fluorescent protein.Synchrotron radiation angiography showed that endorepellin downregulation promoted angiogenesis and increased cortical neovascularization,which may further improve neurobehavioral outcomes.Furthermore,an in vitro study showed that downregulation of endorepellin increased tube formation by human umbilical vein endothelial cells compared with a control.Mechanistic analysis found that endorepellin downregulation may mediate angiogenesis by activating vascular endothelial growth factor-and angiopoietin-1-related signaling pathways.

Heteroatoms doped iron oxide-based catalyst prepared from zinc slag for efficient selective catalytic reduction of NO_(x) with NH_(3)

Excessive emissions of nitrogen oxides from flue gas have imposed various detrimental impacts on environment,and the development of deNO_(x) catalysts with low-cost and high performance is an urgent requirement.Iron oxide-based material has been explored for promising deNO_(x) catalysts.However,the unsatisfactory low-temperature activity limits their practical applications.In this study,a series of excellent low-temperature denitrification catalysts(Ha-FeO_(x)/yZS)were prepared by acid treatment of zinc slag,and the mass ratios of Fe to impure ions was regulated by adjusting the acid concentrations.Ha-FeO_(x)/yZS showed high denitrification performance(>90%)in the range of 180–300℃,and the optimal NO conversion and N2 selectivity were higher than 95%at 250℃.Among them,the Ha-FeO_(x)/2ZS synthesized with 2 mol/L HNO3 exhibited the widest temperature window(175–350℃).The excellent denitrification performance of Ha-FeO_(x)/yZS was mainly attributed to the strong interaction between Fe and impurity ions to inhibit the growth of crystals,making Ha-FeO_(x)/yZS with amorphous structure,nice fine particles,large specific surface area,more surface acid sites and high chemisorbed oxygen.The in-situ DRIFT experiments confirmed that the SCR reaction on the Ha-FeO_(x)/yZS followed both Langmuir-Hinshelwood(L-H)mechanism and Eley-Rideal(E-R)mechanism.The present work proposed a high value-added method for the preparation of cost-effective catalysts from zinc slag,which showed a promising application prospect in NO_(x) removal by selective catalytic reduction with ammonia.

Self-actuating protection mechanisms for safer lithium-ion batteries

Safety issue is still a problem nowadays for the large-scale application of lithium-ion batteries(LIBs)in electric vehicles and energy storage stations.The unsafe behaviors of LIBs arise from the thermal run-away,which is intrinsically triggered by the overcharging and overheating.To improve the safety of LIBs,various protection strategies based on self-actuating reaction control mechanisms(SRCMs)have been proposed,including redox shuttle,polymerizable monomer additive,potential-sensitive separator,thermal shutdown separator,positive-temperature-coefficient electrode,thermally polymerizable addi-tive,and reversible thermal phase transition electrolyte.As build-in protection mechanisms,these meth-ods can sensitively detect either the temperature change inside battery or the potential change of the electrode,and spontaneously shut down the electrode reaction at risky conditions,thus preventing the battery from going into thermal runaway.Given their advantages in enhancing the intrinsic safety of LIBs,this paper overviews the research progresses of SRCMs after a brief introduction of thermal runaway mechanism and limitations of conventional thermal runaway mitigating measures.More importantly,the current states and issues,key challenges,and future developing trends of SRCTs are also discussed and outlined from the viewpoint of practical application,aiming at providing insights and guidance for developing more effective SRCMs for LIBs.

In-situ defect passivation assisted three-step printing of efficient and stable formamidine-lead bromide solar cells

Perovskite solar cells(PSCs)emerge as the most promising photovoltaics(PV)for their high performance and potential convenient cost-effective production routes comparing to the sophomore PV technologies.The printed PSCs with simplified device architecture and fabrication procedures could further enhance the competitive strength of PSC technology.In this work,we present an in-situ defect passivation(ISDP)assisted full-printing of high performance formamidine-lead bromide(FAPbBr_(3))PSCs.Only three rapid printing steps are involved for electron transporting layer(ETL),perovskite and carbon to form a complete solar cell on the low-cost fluorine-doped tin oxide(FTO)substrate.Long-chain polymer monomethyl ether polyethylene glycol is particularly utilized as the ISDP passivator,leading to conformal coating on the rough FTO and defect passivation for both ETL and perovskite during printing.A high efficiency of 10.85%(certified 10.14%)and a high V_(oc)up to 1.57 V are achieved for the printed device.The unencapsulated PSCs maintain above 90%of the initial efficiency after continuously heating at 85℃for 1000 h and over 80%of the efficiency after the maximum power point tracking for 3500 h.The fully printed semitransparent PSCs with carbon grids(CGs)show average visible light transmittance over 33%and an efficiency of 8.81%.

Absence of BCS–BEC crossover in FeSe_(0.45)Te_(0.55) superconductor

In iron-based superconductor Fe(Se,Te), a flat band-like feature near the Fermi level was observed around the Brillouin zone center in the superconducting state. It is under debate whether this is the evidence on the presence of the BCS–BEC[Bardeen–Cooper–Schrieffer(BCS), Bose–Einstein condensation(BEC)] crossover in the superconductor. High-resolution laser-based angle-resolved photoemission measurements are carried out on high quality single crystals of FeSe_(0.45)Te_(0.55) superconductor to address the issue. By employing different polarization geometries, we have resolved and isolated the dyz band and the topological surface band, making it possible to study their superconducting behaviors separately. The dyz band alone does not form a flat band-like feature in the superconducting state and the measured dispersion can be well described by the BCS picture. We find that the flat band-like feature is formed from the combination of the dyz band and the topological surface state band in the superconducting state. These results reveal the origin of the flat band-like feature and rule out the presence of BCS-BEC crossover in Fe(Se,Te) superconductor.