Characteristics of different aged plantations of Ormosia hosiei with regards to soil microbial biomass and enzymatic activities

Stand age is an important indicator of tree growth and life cycle,and has implications for ecological and biological processes.This study examined changes in soil microbial biomass(SMB)as well as enzyme activities of different aged plantations and revealed their relationship to soil properties.SMB,microbial biomass carbon(MBC),microbial biomass nitrogen(MBN),microbial biomass phos-phorous(MBP)and enzyme activities(β-1,4-glucosidase(β-G),β-1,4-xylosidase(β-X),cellobiohydrolase(CBH),leucine aminopeptidase(LAP),β-1,4-n-acetylglucosamine(NAG)and acid phosphatase(ACP))were measured in Oro-mosia hosiei plantations of different ages.The soil qual-ity index(SQI)model assessed soil quality.SMB contents significantly decreased in young(7-year-old)and mature plantations(45-year-old)compared to middle-aged(20-year-old)plantations.Activity of soilβ-G,β-X,CBH and NAG in the 20-year-old plantations was markedly higher than in the other plantations except forβ-G,CBH and NAG in the 45-year-old plantations.Soil organic carbon(SOC),total potassium(TK),total porosity,dissolved organic carbon,nitrate nitrogen(NO_(3)--N)and non-capillary porosity were key factors affecting SMB,while soil bulk density,pH,SOC,NO_(3)--N,TK and forest litter(FL)were the main factors affecting soil enzyme activities.SQI decreased in the order:middle-aged>mature>young.The efficiency of soil organic matter conversion,the effect of nitrogen min-eralization and fixation by microorganisms,and the better efficiency of phosphorus utilization in mid-age plantations,which improves soil physical properties,better facilitates tree growth,and further improves the buffering of the soil against acidity and alkalinity.FL quality was the only soil biological factor affecting soil enzyme activity.Our findings demonstrate that different aged plantations affect soil micro-bial biomass,enzyme activity,and soil quality.

Tailoring spatiotemporal dynamics of plasmonic vortices

Plasmonic vortices confining orbital angular momentums to surface have aroused wide research interest in the last decade.Recent advances of near-field microscopes have enabled the study on the spatiotemporal dynamics of plasmonic vortices,providing a better understanding of optical orbital angular momentums in the evanescent wave regime.However,these works only focused on the objective characterization of plasmonic vortex and have not achieved subjectively tailoring of its spatiotemporal dynamics for specific applications.Herein,it is demonstrated that the plasmonic vortices with the same topological charge can be endowed with distinct spatiotemporal dynamics by simply changing the coupler design.Based on a near-field scanning terahertz microscopy,the surface plasmon fields are directly obtained with ultrahigh spatiotemporal resolution,experimentally exhibiting the generation and evolution divergences during the whole lifetime of plasmonic vortices.The proposed strategy is straightforward and universal,which can be readily applied into visible or infrared frequencies,facilitating the development of plasmonic vortex related researches and applications.

Active-Thermal-Tunable Terahertz Absorber with Temperature-Sensitive Material Thin Film

It is shown that active-tunable terahertz absorbers can be realized in a sandwich-structured system comprising an ultrathin dielectric film(polyimide) on a temperature-sensitive substrate(InSb) with a metal film on the back by utilizing the intrinsic carrier density(N) variation in InSb. When increasing the temperature from 250 to 320 K, N in InSb varied from ～5.50×1015 to ～2.98×1016 cm–3. Fixing the thickness of dielectric film with the value of 1.37 μm, the absorption peak shifted from 1.41 to 3.29 THz while keeping absorption higher than 99%. This active tunability can respond to even a slight temperature perturbation, and shows polarization insensitivity as well as high tolerance of incidence-angle(absorption peak can still exceed 90% even the incidence angle reaches 60°). Besides, the refractive index of polyimide(PI) has thermal stability at the terahertz range and the merit of good workability. These characteristics guarantee the stability of activetunable performance. The peculiarities and innovations of this proposal promise a wide range of high efficiency terahertz devices, such as thermal sensors, spatial light modulators(SLMs) and so on.

Efficient utilization of glass fiber separator for low-cost sodium-ion batteries

The separator is a key component of sodium-ion battery,which greatly affects the electrochemical performances and safety characteristics of the battery.Conventional glass fiber separator cannot meet the requirements of large-scale application because of high cost and poor mechanical properties.Herein,the novel composite separators are prepared by a simple slurry sieving process using glass fiber separator scraps and ordinary qualitative filter paper as raw materials.As the composite mass ratio is 1:1,the composite separator has excellent comprehensive properties,including tensile strength of 15.8 MPa,porosity of 74.3%,ionic conductivity of 1.57×10^(-3)S·cm^(-1)and thermal stability at 210℃.The assembled sodium-ion battery shows superior cycling performance(capacity retention of 94.1%after 500 cycles at 1C)and rate capacity(retention rate of 87.3%at 10C),and it maintains fine interface stability.The above results provide some new ideas for the separator design of high-performance and low-cost sodium-ion batteries.

Recent progress in graphene terahertz modulators

Graphene has been recognized as a promising candidate in developing tunable terahertz(THz)functional devices due to its excellent optical and electronic properties,such as high carrier mobility and tunable conductivity.Here,we review graphene-based THz modulators we have recently developed.First,the optical properties of graphene are discussed.Then,graphene THz modulators realized by different methods,such as gate voltage,optical pump,and nonlinear response of graphene are presented.Finally,challenges and prospective of graphene THz modulators are also discussed.

Superior performance for lithium-ion battery with organic cathode and ionic liquid electrolyte

Organic small structure quinones go with ionic liquids electrolytes would exhibit ultrastable electrochemical properties.In this study,calix[6]quinone(C6Q) cathode was matched with ionic liquid electrolyte Li[TFSI]/[PY13][TFSI](bis(trifluoromethane)sulfonimide lithium salt/N-methyl-N-pro pylpyrrolidinium bis(trifluoromethanesulfonyl)amide) to assemble lithium-ion batteries(LIBs).The electrochemical performance of LIBs was systematically studied.The capacity retention rates of C6Q through 1000 cycles at current densities of 0.2 C and 0.5 C were 70% and 72%,respectively.At 5 C, the capacity was maintained at 190 mAh g^(-1) after 1000 cycles,and 155 mAh g^(-1) even after 10,000 cycles,comparable to inorganic materials.This work would give a big push to the practical process of organic electrode materials in energy storage.

Cobalt phosphide-based composites as anodes for lithium-ion batteries:From mechanism,preparation to performance

With the further requirements of electronic products and powered vehicles,the development of a new generation with low-voltage and high-capacity anode materials is crucial for lithium-ion batteries(LIBs).Transition metal phosphides,especially cobalt phosphide(CoP)composites,have become a research hotspot for LIBs anode materials in recent years due to their high theoretical specific capacity,low polarization,and suitable voltage plateau.This review first systematically discusses the lithium storage mechanism and preparation methods of CoP in current research.Subsequently,the applications of CoP anode materials in LIBs are categorically reviewed,including the composites of CoP with various types of carbon materials and heterostructures.Finally,the challenges and future development directions of CoP anode materials are summarized to provide guidance for further improving the lithium storage performance of CoP and its practical applications.

Synthetic fungal melanin UV absorbers

Agents with robust ultraviolet(UV)absorption capabilities play a vital role in safeguarding organisms and inorganic materials from UV damage.Nonetheless,the synthetic procedures towards these UV absorbers are usually lengthy and complicated,accompanied by undesirable side reactions and the generation of toxic substances.In nature,allomelanin,a class of melanins variant found in melanized fungi near the Chernobyl nuclear power plant,plays crucial roles in the cell wall of melanized fungi,offering resistance to harsh external environments and promising UV resistance capabilities.Notably,allomelanin can be rapidly biosynthesized via the polymerization of 1,8-dihydroxynaphthalene in presence of enzymes in fungi.Inspired by this,we report here a green enzymatic polymerization strategy to efficiently and eco-friendly synthesize polydihydroxynaphthalene(PDHN)-based artificial allomelanin nanoparticles(NPs)with interesting features.Theoretical calculations and experimental results demonstrated that the PDHN NPs exhibited excellent UVabsorption capacity,surpassing another widely used artificial melanin,polydopamine(PDA).Moreover,the light absorption mechanism of PDHN NPs was systematically elucidated for the first time.Then,the PDHN NPs were incorporated with polyvinyl alcohol(PVA)to create an anti-aging composite film with significantly enhanced UV shielding ability.The potential of these composite films in safeguarding plants from UV damage was meticulously verified.Remarkably,these PDHN NPs were first found to produce hydroxyl radicals(·OH)under UV irradiation,offering antibacterial properties that expand their potential applications.

MoS2-based anode materials for lithium-ion batteries:Developments and perspectives

In recent years,significant progress has been achieved in the creation of innovative functional materials for energy storage and conversion.Due to their distinct physicochemical characteristics,ultrathin nanosheets composed of common layered transition metal sulfide materials(MoS2)have demonstrated promise as high-capacity anode materials for lithium-ion batteries(LIBs).Nevertheless,their practical application is severely limited by the tendency of monolayer nanosheets to restack due to strong van der Waals forces,dramatic volume changes during successive cycles,and low intrinsic conductivity.Recent research advances have shown that composite structures and nanowire morphologies with specific morphologies effectively overcome these issues.This paper reviews the recent research progress on molybdenum disulfide-based composites as anode materials for LIBs and discusses in detail the struc-tural characteristics of pure molybdenum disulfide and other composite forms of molybdenum disulfide.In addition,the phase engineering,defect engineering,and lithium storage mechanisms of molybdenum disulfide and the synthesis of molybdenum disulfide-based nanocomposites by different preparation methods are focused on.Finally,we review the design(structure),recent developments,and challenges of novel anode materials and consider their electrochemical performance in Li-ion batteries.

Properties, hazards and valuable metal recovery technologies of red mud: A review

This review presents a summary of the research conducted thus far on the recovery of various types of valuable metals from red mud. The composition, properties, environmental hazards, and current status of comprehensive utilization of red mud were studied. A number of studies have been conducted on the use of red mud as a modifying additive for cement, the development of various catalysts based on red mud, and the recovery of various valuable metals from red mud. Furthermore, we examine several techniques for extracting various types of valuable metals from red mud, including pyrometallurgical recovery, wet leaching recovery, and emerging biobased technology recovery. We investigate the underlying principles, processes, research progress, and the potential for industrial application of these methods, and assess the advantages and disadvantages of each from the perspectives of economic and environmental benefits. Although these methods have certain disadvantages, in general, the recovery of various types of valuable metals from red mud is an effective way to solve the problem of red mud and the supply of metal raw materials. In conclusion, this paper presents an overview of the current state of red mud development and utilization, as well as the various methods employed for the recovery of valuable metals from red mud.

On-chip terahertz orbital angular momentum demultiplexer

The terahertz regime is widely recognized as a fundamental domain with significant potential to address the demands of next-generation wireless communications.In parallel,mode division multiplexing based on orbital angular momentum(OAM)shows promise in enhancing bandwidth utilization,thereby expanding the overall communication channel capacity.In this study,we present both theoretical and experimental demonstrations of an on-chip terahertz OAM demultiplexer.This device effectively couples and steers seven incident terahertz vortex beams into distinct high-quality focusing surface plasmonic beams,and the focusing directions can be arbitrarily designated.The proposed design strategy integrates space-to-chip mode conversion,OAM recognition,and on-chip routing in a compact space with subwavelength thickness,exhibiting versatility and superior performance.

Reflective chiral meta-holography: multiplexing holograms for circularly polarized waves

By allowing almost arbitrary distributions of amplitude and phase of electromagnetic waves to be generated by a layer of sub-wavelength-size unit cells,metasurfaces have given rise to the field of meta-holography.However,holography with circularly polarized waves remains complicated as the achiral building blocks of existing meta-holograms inevitably contribute to holographic images generated by both left-handed and right-handed waves.Here we demonstrate how planar chirality enables the fully independent realization of high-efficiency meta-holograms for one circular polarization or the other.Such circular-polarization-selective meta-holograms are based on chiral building blocks that reflect either left-handed or right-handed circularly polarized waves with an orientation-dependent phase.Using terahertz waves,we experimentally demonstrate that this allows the straightforward design of reflective phase meta-holograms,where the use of alternating structures of opposite handedness yields independent holographic images for circularly polarized waves of opposite handedness with negligible polarization cross-talk.

All-optical active THz metasurfaces for ultrafast polarization switching and dynamic beam splitting

Miniaturized ultrafast switchable optical components with an extremely compact size and a high-speed response will be the core of next-generation all-optical devices instead of traditional integrated circuits,which are approaching the bottleneck of Moore’s Law.Metasurfaces have emerged as fascinating subwavelength flat optical components and devices for light focusing and holography applications.However,these devices exhibit a severe limitation due to their natural passive response.Here we introduce an active hybrid metasurface integrated with patterned semiconductor inclusions for all-optical active control of terahertz waves.Ultrafast modulation of polarization states and the beam splitting ratio are experimentally demonstrated on a time scale of 667 ps.This scheme of hybrid metasurfaces could also be extended to the design of various free-space all-optical active devices,such as varifocal planar lenses,switchable vector beam generators,and components for holography in ultrafast imaging,display,and high-fidelity terahertz wireless communication systems.

Active terahertz beam steering based on mechanical deformation of liquid crystal elastomer metasurface

Active metasurfaces are emerging as the core of next-generation optical devices with their tunable optical responses and flat-compact topography.Especially for the terahertz band,active metasurfaces have been developed as fascinating devices for optical chopping and compressive sensing imaging.However,performance regulation by changing the dielectric parameters of the integrated functional materials exhibits severe limitations and parasitic losses.Here,we introduce a C-shape-split-ring-based phase discontinuity metasurface with liquid crystal elastomer as the substrate for infrared modulation of terahertz wavefront.Line-focused infrared light is applied to manipulate the deflection of the liquid crystal elastomer substrate,enabling controllable and broadband wavefront steering with a maximum output angle change of 22°at 0.68THz.Heating as another control method is also investigated and compared with infrared control.We further demonstrate the performance of liquid crystal elastomer metasurface as a beam steerer,frequency modulator,and tunable beam splitter,which are highly desired in terahertz wireless communication and imaging systems.The proposed scheme demonstrates the promising prospects of mechanically deformable metasurfaces,thereby paving the path for the development of reconfigurable metasurfaces.

利用天然分子构筑功能性3D打印太阳能海水淡化蒸发器

太阳能界面海水淡化无需复杂的基础设施和额外的能源消耗,是一种解决全球淡水危机的有效方法.尽管现在已经开发了许多的太阳能蒸发器,但大多采用了不可持续的合成材料或(且)难以进行精确的微观结构定制,这使得其海水淡化应用的可持续性和性能的进一步提升受到了限制.为了解决这些问题,本文采用了两种天然分子(单宁酸和铁离子),构筑了一种轻质价廉、功能性好的界面海水淡化蒸发器.通过3D打印技术,本研究可以轻松地制备表面具有不同高度锥形阵列结构的蒸发器.该结构可以让照射到蒸发器表面的光发生多重反射,进而增加光吸收,提升光热效率,从而使其海水淡化性能进一步提升,最终在1标准太阳光下实现了1.96 kg m–2h–1的蒸发速率和94.4%的蒸发效率.此外,该蒸发器还具有优异的抗盐性能、重复利用稳定性、抗油污性能及吸附有机染料的能力,可以作为一种绿色、环保、高效的多功能水处理器件.

Terahertz spoof surface-plasmon-polariton subwavelength waveguide

Surface plasmon polaritons(SPPs) with the features of subwavelength confinement and strong enhancements have sparked enormous interest. However, in the terahertz regime, due to the perfect conductivities of most metals, it is hard to realize the strong confinement of SPPs, even though the propagation loss could be sufficiently low. One main approach to circumvent this problem is to exploit spoof SPPs, which are expected to exhibit useful subwavelength confinement and relative low propagation loss at terahertz frequencies. Here we report the design,fabrication, and characterization of terahertz spoof SPP waveguides based on corrugated metal surfaces. The various waveguide components, including a straight waveguide, an S-bend waveguide, a Y-splitter, and a directional coupler, were experimentally demonstrated using scanning near-field terahertz microscopy. The proposed waveguide indeed enables propagation, bending, splitting, and coupling of terahertz SPPs and thus paves a new way for the development of flexible and compact plasmonic circuits operating at terahertz frequencies.

Mechanically reprogrammable Pancharatnam-Berry metasurface for microwaves

Metasurfaces have enabled the realization of several optical functionalities over an ultrathin platform,fostering the exciting field of flat optics.Traditional metasurfaces are achieved by arranging a layout of static meta-atoms to imprint a desired operation on the impinging wavefront,but their functionality cannot be altered.Reconfigurability and programmability of metasurfaces are the next important step to broaden their impact,adding customized on-demand functionality in which each meta-atom can be individually reprogrammed.We demonstrate a mechanical metasurface platform with controllable rotation at the meta-atom level,which can implement continuous Pancharatnam–Berry phase control of circularly polarized microwaves.As the proof-of-concept experiments,we demonstrate metalensing,focused vortex beam generation,and holographic imaging in the same metasurface template,exhibiting versatility and superior performance.Such dynamic control of electromagnetic waves using a single,low-cost metasurface paves an avenue towards practical applications,driving the field of reprogrammable intelligent metasurfaces for a variety of applications.

Broadband terahertz wave generation from an epsilon-near-zero material

Broadband light sources emitting in the terahertz spectral range are highly desired for applications such as noninvasive imaging and spectroscopy.Conventionally,THz pulses are generated by optical rectification in bulk nonlinear crystals with millimetre thickness,with the bandwidth limited by the phase-matching condition.Here we demonstrate broadband THz emission via surface optical rectification from a simple,commercially available 19nmthick indium tin oxide(ITO)thin film.We show an enhancement of the generated THz signal when the pump laser is tuned around the epsilon-near-zero(ENZ)region of ITO due to the pump laser field enhancement associated with the ENZ effect.The bandwidth of the THz signal generated from the ITO film can be over 3 THz,unrestricted by the phasematching condition.This work offers a new possibility for broadband THz generation in a subwavelength thin film made of an ENZ material,with emerging physics not found in existing nonlinear crystals.

Polarization-independent all-silicon dielectric metasurfaces in the terahertz regime

Dielectric metasurfaces have achieved great success in realizing high-efficiency wavefront control in the optical and infrared ranges. Here, we experimentally demonstrate several efficient, polarization-independent, all-silicon dielectric metasurfaces in the terahertz regime. The metasurfaces are composed of cylindrical silicon pillars on a silicon substrate, which can be easily fabricated using etching technology for semiconductors. By locally tailoring the diameter of the pillars, full control over abrupt phase changes can be achieved. To show the controlling ability of the metasurfaces, an anomalous deflector, three Bessel beam generators, and three vortex beam generators are fabricated and characterized. We also show that the proposed metasurfaces can be easily combined to form composite devices with extended functionalities. The proposed controlling method has promising applications in developing low-loss, ultra-compact spatial terahertz modulation devices.

Calix[6]quinone as high-performance cathode for lithium-ion battery

Organic quinone compounds have attracted wide attention due to their high theoretical capacities.Here,a novel cyclic macromolecular calix[6]quinone(C6Q),which possesses 6 p-quinone units and can provide 12 electrochemical active sites,has been applied as a promising cathode material in lithium ion batteries(LIBs).The as-fabricated LIBs exhibited an initial specific capacity as high as 423 mA h g^-1(Ctheo=447 mA h g^-1)at 0.1 C.After 100 cycles,the capacity of C6Q maintained at 216 mA h g^-1,and even after 300 cycles,C6Q still achieved a high specific capacity of 195 mA h g^-1 with negligible capacity fading(as compared with the 100th cycle).Due to the large capacity and wide electrochemical window,C6Q can deliver a specific energy up to 1201 W h kg^-1.In addition,the method of immobilizing C6Q with ordered mesoporous carbon(OMC)CMK-3 could further enhance the electrochemical performance of C6Q.