On the origin of carrier localization in AlInAsSb digital alloy

We compared the photoluminescence(PL)properties of Al In As Sb digital alloy samples with different periods grown on Ga Sb(001)substrates by molecular beam epitaxy.Temperature-dependent S-shape behavior is observed and explained using a thermally activated redistribution model within a Gaussian distribution of localized states.There are two different mechanisms for the origin of the PL intensity quenching for the Al In As Sb digital alloy.The high-temperature activation energy E_(1)is positively correlated with the interface thickness,whereas the low-temperature activation energy E_(2)is negatively correlated with the interface thickness.A quantitative high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)study shows that the interface quality improves as the interface thickness increases.Our results confirm that E_(1)comes from carrier trapping at a state in the In Sb interface layer,while E_(2)originates from the exciton binding energy due to the roughness of the Al As interface layer.

Neuroprotective effect of interleukin-6 regulation of voltage-gated Na^+ channels of cortical neurons is time-and dose-dependent

Interleukin-6 has been shown to be involved in nerve injury and nerve regeneration, but the effects of long-term administration of high concentrations of interleukin-6 on neurons in the central nervous system is poorly understood. This study investigated the effects of 24 hour expo-sure of interleukin-6 on cortical neurons at various concentrations （0.1, 1, 5 and 10 ng/mL） and the effects of 10 ng/mL interleukin-6 exposure to cortical neurons for various durations （2, 4, 8, 24 and 48 hours） by studying voltage-gated Na＋ channels using a patch-clamp technique. Volt-age-clamp recording results demonstrated that interleukin-6 suppressed Na＋ currents through its receptor in a time- and dose-dependent manner, but did not alter voltage-dependent activation and inactivation. Current-clamp recording results were consistent with voltage-clamp recording results. Interleukin-6 reduced the action potential amplitude of cortical neurons, but did not change the action potential threshold. The regulation of voltage-gated Na＋channels in rat corti-cal neurons by interleukin-6 is time- and dose-dependent.

Preferred Revascularization Strategies in Patients with Ischemic Heart Failure: A Meta-Analysis

Clinically,coronary artery bypass grafting (CABG)or percutaneous coronary intervention (PCI)is generally used to treat patients with ischemic heart failure.However, the optimal treatment strategy remains unknown.This study examined the efficacy of the two coronary revascularization strategies for severe ischemic heart failure by using a meta-analysis.Studies comparing the efficacy of CABG and PCI were obtained from PubMed,EMBASE,Google Scholar and Cochrane Central Register of Controlled Trials (CENTRAL).The quality of each eligible article was evaluated by Newcastle-Ottawa Quality Assessment Scale (NOS),and the meta-analysis was performed using Stata version 12.0 software.Eventually,12 studies involving 9248 patients (n=4872 in CABG group;n=4376 in PCI group)were subject to the meta-analysis for subsequent pooling calculation.The pooled hazard ratio (HR)[HR=0.83,95%CI (0.76,0.90),P<0.001; heterogeneity,P=0.218,I^2=22.9%]of CABG compared with that of PCI revealed a statistical superiority of CABG to PCI in terms of the long-term mortality.Furthermore, CABG showed more advantages over PCI with respect to the incidence of myocardial infarction [HR=0.51,95%CI (0.39,0.67),P<0.001;heterogeneity,P=-0.707,I^2=0%]and repeat revascularization [HR=0.40,95%CI (0.27,0.59),P<0.001;heterogeneity,P<0.001, I^2=80.1%].It was concluded that CABG appears to be more advantageous than PCI for the treatment of ischemic heart failure in the given clinical setting.

Material dependence of cities and implications for regional sustainability

Cities rely on massive amounts of physical,chemical,and biological resources to support their growth and metabolism.These‘metabolic inputs’are accumulated in cities to form material stocks in buildings,infrastructures,transportation facilities,and household appliances.This study takes China’s urbanization as an example to illustrate the characteristics of material stock changes in developing countries and compare them with those in developed countries.Results show that(1)material stocks have been growing in China,but have saturated in developed countries,and(2)the major components of urban metabolism are construction and industrial materials(e.g.,steel)in developing countries but biomass(e.g.,food)in developed countries.The changes in the magnitude and types of material stocks can not only measure urban development but also directly link city and its residents,offering advantages in representing urbanization over the existing indices such as population,land use,or gross domestic product(GDP).Given the new insights provided by material stock,we recommend to embrace it as a critical index of urbanization for guiding urban planning and policy-making.

Wet etching and passivation of GaSb-based very long wavelength infrared detectors

The etching and passivation processes of very long wavelength infrared(VLWIR)detector based on the InAs/GaSb/AlSb type-II superlattice have been studied.By studying the effect of each component in the citric acid solution(citric acid,phosphoric acid,hydrogen peroxide,deionized water),the best solution ratio is obtained.After comparing different passivation materials such as sulfide+SiO_(2),Al_(2)O_(3),Si_(3)N_(4) and SU8,it is found that SU8 passivation can reduce the dark current of the device to a greater degree.Combining this wet etching and SU8 passivation,the of VLWIR detector with a mesa diameter of 500μm is about 3.6Ω·cm^(2) at 77 K.

Growth of high material quality InAs/GaSb type-Ⅱ superlattice for long-wavelength infrared range by molecular beam epitaxy

By optimizing theⅤ/Ⅲbeam-equivalent pressure ratio,a high-quality InAs/GaSb type-Ⅱsuperlattice material for the long-wavelength infrared(LWIR)range is achieved by molecular beam epitaxy(MBE).High-resolution x-ray diffraction(HRXRD),atomic force microscopy(AFM),and Fourier transform infrared(FTIR)spectrometer are used to characterize the material growth quality.The results show that the full width at half maximum(FWHM)of the superlattice zero-order diffraction peak,the mismatching of the superlattice zero-order diffraction peak between the substrate diffraction peaks,and the surface roughness get the best results when the beam-equivalent pressure(BEP)ratio reaches the optimal value,which are 28 arcsec,13 arcsec,and 1.63?,respectively.The intensity of the zero-order diffraction peak is strongest at the optimal value.The relative spectral response of the LWIR detector shows that it exhibits a 100%cut-off wavelength of 12.6μm at 77 K.High-quality epitaxial materials have laid a good foundation for preparing high-performance LWIR detector.

Evidence for topological superconductivity: Topological edge states in Bi2Te3/FeTe heterostructure

Majorana fermions have been predicted to exist at the edge states of a two-dimensional topological superconductor.We fabricated single quintuple layer(QL)Bi2Te3/FeTe heterostructure with the step-flow epitaxy method and studied the topological properties of this system by using angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy.We observed the coexistence of robust superconductivity and edge states on the single QL Bi2Te3 islands which can be potential evidence for topological superconductor.

Density wave and topological superconductivity in the magic-angle-twisted bilayer-graphene

The model dependence in the study of the magic-angle twisted bilayer-graphene(MA-TBG)is an important issue in the research area.It has been argued previously that the two-band tight-binding(TB)model(per spin and valley)cannot serve as a start point for succeeding studies as it cannot correctly describe the topological aspect of the continuumtheory model near the Dirac nodes in the mini Brillouin zone(MBZ).For this purpose,we adopt the faithful TB model[Phys.Rev.B 99195455(2019)]with five bands(per spin and valley)as our start point,which is further equipped with extended Hubbard interactions.Then after systematic random-phase-approximation(RPA)based calculations,we study the electron instabilities of this model,including the density wave(DW)and superconductivity(SC),near the van Hove singularity(VHS).Our results are as follows.In the case neglecting the tiny inter-valley exchange interaction,the exact SU(2)K×SU(2)K symmetry leads to the degeneracy between the inter-valley charge DW(CDW)and the spin DW(SDW)(which would be mixed then),and that between the singlet d+id-wave and triplet p+ip-wave topological SCs.When a realistic tiny inter-valley exchange interaction is turned on with nonzero coefficient(J_H=0),the SDW or CDW is favored respectively at the critical point,determined by JH→0-or JH→0+.In the mean time,the degeneracy between the singlet d+id-wave and triplet p+ip-wave topological SCs is also lifted up by the tiny JH.These results are highly similar to the results of our previous study[arXiv:2003.09513]adopting the two-band TB model,with the reason lying in that both models share the same symmetry and Fermi-surface(FS)nesting character near the VHS.Such a similarity suggests that the low-energy physics of the doped MA-TBG is mainly determined by the symmetry and the shape of the FS of the doped system,and is insensitive to other details of the band structure,including the topological aspects near the Dirac nodes in the MBZ.

Malignant pheochromocytoma with cerebral and skull metastasis: A case report and literature review

BACKGROUND Malignant pheochromocytoma with cerebral and skull metastasis is a very rare disease.Combining our case with 16 previously reported cases identified from a PubMed search,an analysis of 17 cases of malignant cerebral pheochromocytoma was conducted.This literature review aimed to provide information on clinical manifestations,radiographic and histopathological features,and treatment strategies of this condition.CASE SUMMARY A 60-year-old man was admitted with a progressive headache and enlarging scalp mass lasting for 3 mo.Radiographic images revealed a left temporal biconvexshaped epidural mass and multiple lytic lesions.The patient underwent a left temporal craniotomy for resection of the temporal tumor.Histopathological analysis led to identification of the mass as malignant pheochromocytoma.The patient’s symptoms were alleviated at the postoperative 3-mo clinical follow-up.However,metastatic pheochromocytoma lesions were found on the right 6th rib and the 6th to 9th thoracic vertebrae on a 1-year clinical follow-up computed tomography scan.CONCLUSION Magnetic resonance spectroscopy and histopathological examination are necessary to make an accurate differential diagnosis between malignant cerebral pheochromocytoma and meningioma.Surgery is regarded as the first choice of treatment.

Serum homocysteine concentrations of Chinese intellectuals and the influential factors concerned

Objective: To observe the concentration of se-rum homocysteine in intellectuals and the re-lated influential factors. Methods: The concen-trations serum homocysteine and saliva cortisol were measured in 138 intellectuals from three cities, Tianjin, Guangzhou and Chengdu in China. All the subjects had senior titles of tech-nical post, aged 40-69 years. Results: The mean value of serum homocysteine concentration in intellectuals was 20.6±0.8μmol/L, higher than the reference value. With the increase of cortisol levels the homocysteine concentrations rise (P <0.05). The mean value of homocysteine con-centration was highest in 40-49 years old group. Men had higher homocysteine level than women in this investigation. According to the mean value of homocysteine concentration among different cities, Tianjin was highest, Chengdu medium, Guangzhou lowest. Conclusion: The serum homocysteine concentration of intellec-tuals is higher than the reference value. The stress level, gender and resident cities might contribute to the differences in serum homo-cysteine concentration in Chinese intellectuals.

Emergent symmetry in quantum phase transition:From deconfined quantum critical point to gapless quantum spin liquid

The emergence of exotic quantum phenomena in frustrated magnets is rapidly driving the development of quantum many-body physics,raising fundamental questions on the nature of quantum phase transitions.Here we unveil the behaviour of emergent symmetry involving two extraordinarily representative phenomena,i.e.,the deconfined quantum critical point(DQCP)and the quantum spin liquid(QSL)state.Via large-scale tensor network simulations,we study a spatially anisotropic spin-1/2 square-lattice frustrated antiferromagnetic(AFM)model,namely the J1x-J1y-J2 model,which contains anisotropic nearestneighbor couplings J1x,J1y and the next nearest neighbor coupling J2.For small J1y/J1x,by tuning J2,a direct continuous transition between the AFM and valence bond solid phase is observed.With growing J1y/J1x,a gapless QSL phase gradually emerges between the AFM and VBS phases.We observe an emergent O(4)symmetry along the AFM–VBS transition line,which is consistent with the prediction of DQCP theory.Most surprisingly,we find that such an emergent O(4)symmetry holds for the whole QSL–VBS transition line as well.These findings reveal the intrinsic relationship between the QSL and DQCP from categorical symmetry point of view,and strongly constrain the quantum field theory description of the QSL phase.The phase diagram and critical exponents presented in this paper are of direct relevance to future experiments on frustrated magnets and cold atom systems.

Spatiotemporal dynamics of city-level WEEE generation from different sources in China

China stands as one of the leading producers of waste electrical and electronic equipment(WEEE),facing significant challenges in managing the substantial volumes generated.Despite existing regulations,the informal treatment of WEEE persists in some areas due to inadequate recycling networks at the city level.Consequently,there is a critical need for a detailed geographical mapping of WEEE generation to address improper disposal practices effectively.This study introduces the cMAC–EEEs(city Material Cycles and Manufactured Capital–EEEs)database,providing estimates of WEEE generation across approximately 300 prefecture-level cities from 1978 to 2017.It focuses on five commonly used types of electrical and electronic equipment(refrigerators,air conditioners,washing machines,computers,TVs)originating from three key sources(urban residents,rural residents,enterprises).The findings reveal(1)significant spatial variation in WEEE generation within China,with eastern and central city clusters identified as hotspots,particularly for urban residents and enterprises,while the western region exhibits the highest growth rate in WEEE generation,notably among rural residents.(2)The growth in obsolete computers and air conditioners is prominent,especially in rural areas and among enterprises,whereas the generation of obsolete TVs,washing machines,and refrigerators is leveling off and expected to decrease in some urban areas.(3)Enterprises account for a substantial portion of WEEE generation,though uncertainties exist,necessitating further refinement.The study highlights that less developed regions lack adequate recycling facilities,with specific limitations in refrigerators and air conditioners recycling capabilities.To enhance WEEE management,it advocates for increased interregional collaboration and capacity building in less developed areas.Additionally,the regulation of WEEE from private enterprises requires improvement.At the product level,a greater focus on recycling practices for refrigerators and air conditioners is recommended.

Urban agriculture as nature-based solutions:Three key strategies to tackle emerging issues on food security in Chinese cities under climatic and non-climatic challenges

1Introduction Achieving food and water security,according to the United Nations Sustainable Development Goals(SDGs),only requires a minimal environmental cost(Batalini de Macedo et al.,2022).However,in terms of agriculture,blindly devoting efforts to offset low-productivity farming or production techniques and industries,without systematic water,fertiliser,farm residue,tillage,and fallow management,will eventually interrupt the carbon sink under the soil and escalate greenhouse gas emissions,which is not helpful to meeting global climate targets.Thus,sciencebased land management practices are essential to decouple agricultural productivity from greenhouse gas emissions(Buscardo et al.,2021).

面向可持续发展的资源关联研究:现状与展望

中国传统文化认为“金、木、水、火、土”五行相生相克,这是最早描述物质要素之间相互关联的系统性学说.在现代科学语境中,支撑和制约可持续发展的关键自然资源主要包括矿产资源、生物质资源、水资源、能源和土地资源,大致与“五行”对应.它们之间存在广泛的依赖、替代、竞争和互补关系.近10年来,全球兴起了“资源关联”(resources nexus)的研究热潮.本文对资源关联研究进行了文献计量分析,综述了常用研究方法、模型和数据,分析了资源关联的驱动力、影响因素及其对社会经济可持续发展的作用.主要发现如下:(1)日益紧密的资源关联关系对可持续发展的影响不断增强;(2)全球化驱使资源关联由区域性向全球性开放系统延伸;(3)资源关联使可持续发展目标之间既存在协同也存在冲突;(4)资源关联对社会经济可持续发展转型既有促进也有制约作用.未来可以在四方面深化该领域的研究:(1)拓展资源关联的研究范畴;(2)揭示资源关联的内在机制及其影响;(3)构建通用、开放、共享、可拓展的数据平台;(4)加强资源关联研究的可持续发展决策支撑能力.

Carbon neutrality needs a circular metal-energy nexus

Carbon neutrality requires systematic transformations of both energy and metal systems.These transformations are not isolated but rather interlinked and interdependent,such that trade-offs between different strategies exist.Herein,we explore the critical interlinkages between energy and metal systems and further propose a circular metal-energy nexus to advance global coordinated actions towards a carbon-neutral future.

In-use product and steel stocks sustaining the urbanization of Xiamen, China

Introduction:In-use product and material stocks are the amount of concerned manufactured products and materials in active use,and are essential components of urban ecosystem.Methods:This study estimates the dynamic in-use stocks of steel-containing products and steel in the city of Xiamen,China,during 1980–2015 by applying a bottom-up accounting approach.We incorporate 55 categories of steel-containing products that are classified into five end-use sectors(i.e.,buildings,infrastructure,transportation equipment,machinery,and domestic appliances).Outcomes and Discussion:In-use stocks of 51%of the studied products kept increasing during 1980–2015,especially after 2000.Steel stocks have grown up to 4.9±1.4 tons per capita(t/cap)in 2015,from 0.5±0.2 t/cap in 1980.Buildings are the largest reservoirs,although its share decreased from 89%in 1980 to 68%in 2015.The dynamic spatial distribution indicates that steel stocks gradually expanded from urban core to suburban areas.Conclusion:Theresults help to explore how a city’s urbanization is sustained by the in-use stocks growth.In-use steel stocks,of which the growth is highly correlated to and probably driven by the population growth,GDP increase,and urban built-up area expansion,may serve as a supplementary indicator for urbanization.

Gapless quantum spin liquid and global phase diagram of the spin-1/2 J_(1)-J_(2) square antiferromagnetic Heisenberg model

The nature of the zero-temperature phase diagram of the spin-1/2 J_(1)-J_(2)Heisenberg model on a square lattice has been debated in the past three decades,and it remains one of the fundamental problems unsettled in the study of quantum many-body theory.By using the state-of-the-art tensor network method,specifically,the finite projected entangled pair state(PEPS)algorithm,to simulate the global phase diagram of the J_(1)-J_(2)Heisenberg model up to 24×24 sites,we provide very solid evidences to show that the nature of the intermediate nonmagnetic phase is a gapless quantum spin liquid(QSL),whose spin-spin and dimer-dimer correlations both decay with a power law behavior.There also exists a valence-bond solid(VBS)phase in a very narrow region 0.56■J_(2)/J_(1)≤0.61 before the system enters the well known collinear antiferromagnetic phase.We stress that we make the first detailed comparison between the results of PEPS and the well-established density matrix renormalization group(DMRG)method through one-to-one direct benchmark for small system sizes,and thus give rise to a very solid PEPS calculation beyond DMRG.Our numerical evidences explicitly demonstrate the huge power of PEPS for highly frustrated spin systems.Finally,an effective field theory is also proposed to understand the physical nature of the discovered gapless QSL and its relation to deconfined quantum critical point(DQCP).

Classification of topological phases in one dimensional interacting non-Hermitian systems and emergent unitarity

Topological phases in non-Hermitian systems have become fascinating subjects recently.In this paper,we attempt to classify topological phases in 1D interacting non-Hermitian systems.We begin with the non-Hermitian generalization of the Su-Schrieffer-Heeger(SSH)model and discuss its many-body topological Berry phase,which is well defined for all interacting quasi-Hermitian systems(non-Hermitian systems that have real energy spectrum).We then demonstrate that the classification of topological phases for quasi-Hermitian systems is exactly the same as their Hermitian counterparts.Finally,we construct the fixed point partition function for generic 1D interacting non-Hermitian local systems and find that the fixed point partition function still has a one-to-one correspondence to their Hermitian counterparts.Thus,we conclude that the classification of topological phases for generic 1D interacting non-Hermitian systems is still exactly the same as Hermitian systems.

Evolution of the global polyethylene waste trade system

Introduction:China’s import bans on solid wastes starting from 2017 have challenged the global trade system of plastic wastes,which remains poorly characterized.This study chooses polyethylene(PE)as a case and aims to map out the global trade networks of PE waste(GPETN)from 1976 to 2017.Outcomes:We find that the size and complexity of the GPETN had been growing until 2016.After the mid-1990s,PE waste basically flowed from developed economies,mainly the EU and the US,to developing economies such as China.Since 2001 when admitted into the WTO,China’s PE waste import surged until 2014 when it absorbed over 60%of global export.Regulations on solid waste import following the Green Fence campaign in 2013 resulted in substantial reductions in China’s import as well as the global export of PE waste after 2014.Several other developing economies,such as Malaysia,Turkey,and Vietnam,had transitioned to net importers,but their imports were insufficient to replace China as new recycling bases for PE waste.Conclusion:The results highlight the urgent need of a joint effort for developed and developing countries to build a stronger global circular economy system with sufficient capacity to treat PE waste locally.

Temporal and spatial variation in the environmental impacts of China’s resource extraction at the provincial scale

Introduction:Over the past two decades,China has experienced rapid economic development,which has not only led to a rapid increase in the use of raw materials but has also created environmental problems.This research analyzes the environmental impacts of resource extraction in China at the provincial level,and fully considers the environmental impact of various resources extraction.In addition,it is the first time to quantitatively study the spatial pattern and evolution characteristics of the environmental impacts of China’s resource extraction from multiple perspectives by means of spatial visualization.Outcomes:The results showed that the center of gravity of abiotic depletion potential(ADP)moved northwest,respiratory inorganics(RI)moved southwest and global warming potential(GWP)moved west.The results of the standard deviation ellipse showed that RI and GWP varied over time and space,while ADP showed a discrete trend.In addition,the distribution of the four in the northeast-southwest direction became more prominent.Conclusion:To mitigate the environmental impacts of resource extraction,we recommend that regional governments implement measures to control environmental impacts in the provinces within the distributed ellipse and design targeted policies based on actual conditions.