锌粉置换渣浸出过程中镓的溶解行为及改善方法

针对丹霞冶炼厂锌粉置换渣浸出过程中镓浸出率偏低问题,采用ICP-AES、XRD与SEM-EDS对不同批次锌粉置换渣化学成分、物相与形貌进行详细分析。与正常生产锌粉置换渣相比,异常锌粉置换渣中镓主要赋存于黄钾铁矾之中,造成镓浸出困难。对锌粉置换渣氧压浸出过程进行分析,镓、砷和铁溶出规律较为一致:增大硫酸浓度和液固比有利于镓、铁和砷的浸出,但提高温度和氧气分压对镓、铁和砷溶出不利。依据上述研究结果,提出强化镓浸出效率的改善措施,弱化一段氧压浸出(分别降低反应温度和压缩空气总压至90℃和0.2 MPa)与强化三段常压浸出(分别提高硫酸浓度和反应温度至160 g/L和85℃),镓的浸出效率由77.83%提高至96.46%。

Fine mapping and validation of a stable QTL for thousand-kernel weight in wheat(Triticum aestivum L.)

Thousand-kernel weight(TKW)is a measure of grain weight,a target of wheat breeding.The object of this study was to fine-map a stable quantitative trait loci(QTL)for TKW and identify its candidate gene in a recombinant inbred line(RIL)population derived from the cross of Kenong 9204(KN9204)and Jing411(J411).On a high-density genetic linkage map,24,26 and 25 QTL were associated with TKW,kernel length(KL),and kernel width(KW),respectively.A major and stable QTL,QTkw-2D,was mapped to an8.3 cM interval on chromosome arm 2DL.By saturation of polymorphic markers in its target region,QTkw-2D was confined to a 9.13 Mb physical interval using a secondary mapping population derived from a residually heterozygous line(F6:7).This interval was further narrowed to 2.52 Mb using QTkw-2D near-isogenic lines(NILs).NILs~(KN9204)had higher fresh and dry weights than NILsJ411at various grain-filling stages.The TKW and KW of NILs~(KN9204)were much higher than those of NILsJ411in field trials.By comparison of both DNA sequence and expression between KN9204 and J411,TraesCS2D02G460300.1(TraesKN2D01HG49350)was assigned as a candidate gene for QTkw-2D.This was confirmed by RNA sequencing(RNA-seq)of QTkw-2D NILs.These results provide the basis of map-based cloning of QTkw-2D,and DNA markers linked to the candidate gene may be used in marker-assisted selection.

气相SiO_(2)复合水凝胶聚合物电解质用于近中性锌-空气电池

近中性锌-空气电池具有对锌负极良好的沉积/剥离相容性和对空气中二氧化碳的化学稳定性,在长循环方面展现出极高的应用前景。然而,液态电解质固有的水分挥发问题和可穿戴设备所需的柔性等需求,限制了这一体系的实际应用。本研究复合了具有高离子电导率和机械强度的聚丙烯酰胺聚合物骨架、具有丰富硅羟基的保水添加剂气相SiO_(2)和对二氧化碳稳定的近中性电解液,制备了气相SiO_(2)复合水凝胶聚合物电解质(SiO_(2)-HPE)。所合成的SiO_(2)-HPE聚合程度高,表面孔道丰富且元素分布均匀。SiO_(2)表面丰富的硅羟基通过改变HPE中的氢键网络,加强了对水分子的束缚,SiO_(2)-HPE因此展现出了良好的保水性、优异的机械性能和较高的离子电导率,是一种理想的柔性锌-空气电池电解质。基于SiO_(2)-HPE组装的近中性锌-空气电池,在相对湿度为30%的条件下,循环寿命可达200 h。此外,基于SiO_(2)-HPE的柔性近中性锌-空气电池器件在弯曲和剪切等特殊条件下都展现出优异的性能,并且可作为电源为不同的用电器供电,是一种极具潜力的下一代电化学储能器件。

可见光催化CO_(2)参与的芳基烯烃碳碳双键断键羧基化反应

烯烃广泛存在于自然界中,在医药、农药和材料等领域具有重要应用.烯烃的C=C键断裂和转化是许多工业过程的基础,可以实现烃类资源的重组与利用.目前,C=C键参与的氧化裂解和烯烃复分解反应已有广泛的研究.相比而言,C=C键参与的还原裂解虽然是烯烃与一系列亲电试剂反应合成功能分子的重要途径,但受限于烯烃自身结构和反应特点,该过程存在较大的挑战,目前研究很少.CO_(2)具有储量丰富、廉价易得、无毒且可循环再生等优点,是合成多种大宗化学品及精细化学品的理想碳一资源.然而,CO_(2)由于热力学稳定性及动力学惰性,在温和条件下难以高效、高选择性转化.因此,利用CO_(2)参与烯烃C=C键还原裂解,选择性构建高值化合物,是一个重要且具有挑战性的研究方向.近年来,可见光催化由于具有反应条件温和、官能团兼容性高等优点,为有机合成等领域提供了新的发展机遇.本文利用二环己基甲基胺作为电子给体,成功实现了可见光催化CO_(2)参与的芳基烯烃C=C键断键羧基化反应.该反应成功的关键在于,二环己基甲基胺既能高效还原淬灭激发态光敏剂并参与烯烃的胺基烷基-羧基化反应,又不明显抑制胺基烷基化中间体对激发态光敏剂的还原淬灭.研究结果表明,多种不同取代(如给电子基和吸电子基)的芳基烯烃均可与CO_(2)发生羧基化反应,高效高选择性地构建了一系列官能团丰富的芳基乙酸类化合物(如萘普生等药物分子).该方法具有反应条件温和(1 atm,室温)、官能团耐受性好以及可用于合成药物衍生物等特点.此外,本文通过氘代实验等机理研究和密度泛函理论计算证明,胺甲基羧化中间体、苄基自由基和苄基碳负离子都是该反应的关键中间体,并提出了可能的反应机理:首先,二环己基甲基胺还原淬灭激发态光敏剂,产生α-胺基碳自由基,与芳基烯烃发生自由基加成反应,得到苄基自由基,进而被还原态光敏剂还原为碳负离子,对CO_(2)亲核进攻得到烯烃的胺基烷基-羧基化中间体;作为电子给体,该中间体可以淬灭另一分子的激发态光敏剂,并通过分子内去质子化过程,产生α-胺基碳自由基物种,进而经历自由基型β-C断裂,生成热力学更稳定的羧基化苄基自由基,从而实现了烯烃C=C键的还原裂解;最后,新产生的苄基自由基被进一步还原为碳负离子,经历质子化过程后得到目标产物.综上,本文以还原裂解的方式丰富了C=C键断键官能团化反应领域,在温和条件下实现了CO_(2)的高效高选择性转化,合成了高附加值的芳基乙酸类化合物,阐明了反应机制,为烯烃和CO_(2)的同时高值化利用提供了新思路,为后续相关反应的开发和应用提供参考.

聚丙烯熔喷空气过滤材料表面仿生改性及性能

聚丙烯(PP)熔喷空气过滤材料的抗菌性能较差,细菌、霉菌等微生物会寄生于材料表面。文中利用仿生改性法,以单宁酸(TA)为抗菌改性剂、CuSO_(4)/H_(2)O_(2)为促进剂制备了具有优异抗菌性能的PP/TA熔喷空气过滤材料。分析讨论了TA改性溶液浓度和CuSO_(4)/H_(2)O_(2)促进剂的加入对PP/TA熔喷空气过滤材料结构与性能的影响。结果表明,CuSO_(4)/H_(2)O_(2)促进剂的加入将TA改性时间从24 h缩短至40 min,并增强了PP/TA熔喷空气过滤材料的改性牢度。当TA浓度为6 g/L时,PP/TA熔喷空气过滤材料相较于PP熔喷空气过滤材料其过滤效率和压降分别提升了2.7%和4 Pa,水接触角降低了17.5°;且TA改性对PP熔喷空气过滤材料的驻极性能并无影响,驻极后PP/TA熔喷过滤材料的过滤效率为95.56%,压降为38 Pa,且具备良好的抗菌性能。同时,CuSO_(4)/H_(2)O_(2)促进剂的加入在材料表面引入了Cu^(2+),增强了抗菌效果。

Regulation of specific abnormal calcium signals in the hippocampal CA1 and primary cortex M1 alleviates the progression of temporal lobe epilepsy

Temporal lobe epilepsy is a multifactorial neurological dysfunction syndrome that is refractory,resistant to antiepileptic drugs,and has a high recurrence rate.The pathogenesis of temporal lobe epilepsy is complex and is not fully understood.Intracellular calcium dynamics have been implicated in temporal lobe epilepsy.However,the effect of fluctuating calcium activity in CA1 pyramidal neurons on temporal lobe epilepsy is unknown,and no longitudinal studies have investigated calcium activity in pyramidal neurons in the hippocampal CA1 and primary motor cortex M1 of freely moving mice.In this study,we used a multichannel fiber photometry system to continuously record calcium signals in CA1 and M1 during the temporal lobe epilepsy process.We found that calcium signals varied according to the grade of temporal lobe epilepsy episodes.In particular,cortical spreading depression,which has recently been frequently used to represent the continuously and substantially increased calcium signals,was found to correspond to complex and severe behavioral characteristics of temporal lobe epilepsy ranging from gradeⅡto gradeⅤ.However,vigorous calcium oscillations and highly synchronized calcium signals in CA1 and M1 were strongly related to convulsive motor seizures.Chemogenetic inhibition of pyramidal neurons in CA1 significantly attenuated the amplitudes of the calcium signals corresponding to gradeⅠepisodes.In addition,the latency of cortical spreading depression was prolonged,and the above-mentioned abnormal calcium signals in CA1 and M1 were also significantly reduced.Intriguingly,it was possible to rescue the altered intracellular calcium dynamics.Via simultaneous analysis of calcium signals and epileptic behaviors,we found that the progression of temporal lobe epilepsy was alleviated when specific calcium signals were reduced,and that the end-point behaviors of temporal lobe epilepsy were improved.Our results indicate that the calcium dynamic between CA1 and M1 may reflect specific epileptic behaviors corresponding to different grades.Furthermore,the selective regulation of abnormal calcium signals in CA1 pyramidal neurons appears to effectively alleviate temporal lobe epilepsy,thereby providing a potential molecular mechanism for a new temporal lobe epilepsy diagnosis and treatment strategy.

Neural stem cell-derived exosomes promote mitochondrial biogenesis and restore abnormal protein distribution in a mouse model of Alzheimer's disease

Mitochondrial dysfunction is a hallmark of Alzheimer’s disease.We previously showed that neural stem cell-derived extracellular vesicles improved mitochondrial function in the cortex of AP P/PS1 mice.Because Alzheimer’s disease affects the entire brain,further research is needed to elucidate alterations in mitochondrial metabolism in the brain as a whole.Here,we investigated the expression of several important mitochondrial biogenesis-related cytokines in multiple brain regions after treatment with neural stem cell-derived exosomes and used a combination of whole brain clearing,immunostaining,and lightsheet imaging to clarify their spatial distribution.Additionally,to clarify whether the sirtuin 1(SIRT1)-related pathway plays a regulatory role in neural stem cell-de rived exosomes interfering with mitochondrial functional changes,we generated a novel nervous system-SIRT1 conditional knoc kout AP P/PS1mouse model.Our findings demonstrate that neural stem cell-de rived exosomes significantly increase SIRT1 levels,enhance the production of mitochondrial biogenesis-related fa ctors,and inhibit astrocyte activation,but do not suppress amyloid-βproduction.Thus,neural stem cell-derived exosomes may be a useful therapeutic strategy for Alzheimer’s disease that activates the SIRT1-PGC1αsignaling pathway and increases NRF1 and COXIV synthesis to improve mitochondrial biogenesis.In addition,we showed that the spatial distribution of mitochondrial biogenesis-related factors is disrupted in Alzheimer’s disease,and that neural stem cell-derived exosome treatment can reverse this effect,indicating that neural stem cell-derived exosomes promote mitochondrial biogenesis.

Dual‑Atom Nanozyme Eye Drops Attenuate Inflammation and Break the Vicious Cycle in Dry Eye Disease

Dry eye disease(DED)is a major ocular pathology worldwide,causing serious ocular discomfort and even visual impairment.The incidence of DED is gradually increasing with the highfrequency use of electronic products.Although inflammation is core cause of the DED vicious cycle,reactive oxygen species(ROS)play a pivotal role in the vicious cycle by regulating inflammation from upstream.Therefore,current therapies merely targeting inflammation show the failure of DED treatment.Here,a novel dual-atom nanozymes(DAN)-based eye drops are developed.The antioxidative DAN is successfully prepared by embedding Fe and Mn bimetallic single-atoms in N-doped carbon material and modifying it with a hydrophilic polymer.The in vitro and in vivo results demonstrate the DAN is endowed with superior biological activity in scavenging excessive ROS,inhibiting NLRP3 inflammasome activation,decreasing proinflammatory cytokines expression,and suppressing cell apoptosis.Consequently,the DAN effectively alleviate ocular inflammation,promote corneal epithelial repair,recover goblet cell density and tear secretion,thus breaking the DED vicious cycle.Our findings open an avenue to make the DAN as an intervention form to DED and ROSmediated inflammatory diseases.

Swelling behaviors of heterogeneous red-bed mudstone subjected to different vertical stresses

In this study,the axial swelling strain of red-bed mudstone under different vertical stresses are measured by swell-under-load method,and the microstructure of mudstone after hygroscopic swelling is studied by mercury intrusion porosimetry(MIP).The weakening coefficient and Weibull distribution function are introduced into the coupling model of mudstone moisture diffusion-swelling deformation-fracture based on finite-discrete element method(FDEM).The weakening effect of moisture on mudstone's mechanical parameters,as well as the heterogeneity of swelling deformation and stress distribution,is considered.The microcrack behavior and energy evolution of mudstone during hygroscopic swelling deformation under different vertical stresses are studied.The results show that the axial swelling strain of mudstone decreases with increase of the vertical stress.At low vertical stresses,moisture absorption in mudstone leads to formation of cracks caused by hydration-induced expansion.Under high vertical stresses,a muddy sealing zone forms on the mudstone surface,preventing further water infiltration.The simulation results of mudstone swelling deformation also demonstrate that it involves both swelling of the mudstone matrix and swelling caused by crack expansion.Notably,crack expansion plays a dominant role in mudstone swelling.With increasing vertical stress,the cracks in mudstone change from tensile cracks to shear cracks,resulting in a significant reduction in the total number of cracks.While the evolution of mudstone kinetic energy shows similarities under different vertical stresses,the evolution of strain energy varies significantly due to the presence of different types of cracks in the mudstone.The findings provide a theoretical basis for understanding the hygroscopic swelling deformation mechanism of red-bed mudstone at various depths.

Characterization of Domeless receptors and the role of Bd Domeless3 in anti-symbiont-like virus defense in Bactrocera dorsalis

The Janus kinase/signal transducers and activators of transcription(JAK/STAT)signaling pathway play a pivotal role in innate immunity.Among invertebrates,Domeless receptors serve as the key upstream regulators of this pathway.In our study on Bactrocera dorsalis,we identified three cytokine receptors:BdDomeless1,BdDomeless2,and BdDomeless3.Each receptor encompasses five fibronectin-type-III-like(FN III)extracellular domains and a transmembrane domain.Furthermore,these receptors exhibit the increased responsiveness to diverse pathogenic challenges.Notably,only BdDomeless3 is upregulated during symbiont-like viral infections.Moreover,silencing BdDomeless3 enhanced the infectivity of Bactrocera dorsalis cripavirus(BdCV)and B.dorsalis picorna-like virus(BdPLV),underscoring BdDomeless3’s crucial role in antiviral defense of B.dorsalis.Following the suppression of Domeless3 expression,six antimicrobial peptide genes displayed decreased expression,potentially correlating with the rise in viral infectivity.To our knowledge,this is the first study identifying cytokine receptors associated with the JAK/STAT pathway in tephritid flies,shedding light on the immune mechanisms of B.dorsalis.

Efficient Polytelluride Anchoring for Ultralong-Life Potassium Storage: Combined Physical Barrier and Chemisorption in Nanogrid-in-Nanofiber

Metal tellurides(MTes) are highly attractive as promising anodes for high-performance potassium-ion batteries. The capacity attenuation of most reported MTe anodes is attributed to their poor electrical conductivity and large volume variation. The evolution mechanisms, dissolution properties, and corresponding manipulation strategies of intermediates(K-polytellurides, K-pTe_(x)) are rarely mentioned. Herein,we propose a novel structural engineering strategy to confine ultrafine CoTe_(2) nanodots in hierarchical nanogrid-in-nanofiber carbon substrates(CoTe_(2)@NC@NSPCNFs) for smooth immobilization of K-pTe_(x) and highly reversible conversion of CoTe_(2) by manipulating the intense electrochemical reaction process. Various in situ/ex situ techniques and density functional theory calculations have been performed to clarify the formation, transformation, and dissolution of K-pTe_(x)(K_(5)Te_(3) and K_(2)Te), as well as verifying the robust physical barrier and the strong chemisorption of K_(5)Te_(3) and K_(2)Te on S, N co-doped dual-type carbon substrates. Additionally, the hierarchical nanogrid-in-nanofiber nanostructure increases the chemical anchoring sites for K-pTe_(x), provides sufficient volume buffer space, and constructs highly interconnected conductive microcircuits, further propelling the battery reaction to new heights(3500 cycles at 2.0 A g^(-1)). Furthermore, the full cells further demonstrate the potential for practical applications. This work provides new insights into manipulating K-pTe_(x) in the design of ultralong-cycling MTe anodes for advanced PIBs.

Theoretical and experimental investigation of the resonance responses and chaotic dynamics of a bistable laminated composite shell in the dynamic snap-through mode

The dynamic model of a bistable laminated composite shell simply supported by four corners is further developed to investigate the resonance responses and chaotic behaviors.The existence of the 1:1 resonance relationship between two order vibration modes of the system is verified.The resonance response of this class of bistable structures in the dynamic snap-through mode is investigated,and the four-dimensional(4D)nonlinear modulation equations are derived based on the 1:1 internal resonance relationship by means of the multiple scales method.The Hopf bifurcation and instability interval of the amplitude frequency and force amplitude curves are analyzed.The discussion focuses on investigating the effects of key parameters,e.g.,excitation amplitude,damping coefficient,and detuning parameters,on the resonance responses.The numerical simulations show that the foundation excitation and the degree of coupling between the vibration modes exert a substantial effect on the chaotic dynamics of the system.Furthermore,the significant motions under particular excitation conditions are visualized by bifurcation diagrams,time histories,phase portraits,three-dimensional(3D)phase portraits,and Poincare maps.Finally,the vibration experiment is carried out to study the amplitude frequency responses and bifurcation characteristics for the bistable laminated composite shell,yielding results that are qualitatively consistent with the theoretical results.

Snap-through behaviors and nonlinear vibrations of a bistable composite laminated cantilever shell:an experimental and numerical study

The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical approaches.An improved experimental specimen is designed in order to satisfy the cantilever support boundary condition,which is composed of an asymmetric region and a symmetric region.The symmetric region of the experimental specimen is entirely clamped,which is rigidly connected to an electromagnetic shaker,while the asymmetric region remains free of constraint.Different motion paths are realized for the bistable cantilever shell by changing the input signal levels of the electromagnetic shaker,and the displacement responses of the shell are collected by the laser displacement sensors.The numerical simulation is conducted based on the established theoretical model of the bistable composite laminated cantilever shell,and an off-axis three-dimensional dynamic snap-through domain is obtained.The numerical solutions are in good agreement with the experimental results.The nonlinear stiffness characteristics,dynamic snap-through domain,and chaos and bifurcation behaviors of the shell are quantitatively analyzed.Due to the asymmetry of the boundary condition and the shell,the upper stable-state of the shell exhibits an obvious soft spring stiffness characteristic,and the lower stable-state shows a linear stiffness characteristic of the shell.

Mechanical behavior and response mechanism of porous metal structures manufactured by laser powder bed fusion under compressive loading

Al Si10Mg porous protective structure often produces different damage forms under compressive loading,and these damage modes affect its protective function.In order to well meet the service requirements,there is an urgent need to comprehensively understand the mechanical behavior and response mechanism of AlSi10Mg porous structures under compressive loading.In this paper,Al Si10Mg porous structures with three kinds of volume fractions are designed and optimized to meet the requirements of high-impact,strong-energy absorption,and lightweight characteristics.The mechanical behaviors of AlSi10Mg porous structures,including the stress-strain relationship,structural bearing state,deformation and damage modes,and energy absorption characteristics,were obtained through experimental studies at different loading rates.The damage pattern of the damage section indicates that AlSi10Mg porous structures have both ductile and brittle mechanical properties.Numerical simulation studies show that the AlSi10Mg porous structure undergoes shear damage due to relative misalignment along the diagonal cross-section,and the damage location is almost at 45°to the load direction,which is the most direct cause of its structural damage,revealing the damage mechanism of AlSi10Mg porous structures under the compressive load.The normalized energy absorption model constructed in the paper well interprets the energy absorption state of Al Si10Mg porous structures and gives the sensitive location of the structures,and the results of this paper provide important references for peers in structural design and optimization.

Universal architecture and defect engineering dual strategy for hierarchical antimony phosphate composite toward fast and durable sodium storage

Antimony(Sb)-ba sed anode materials are feasible candidates for sodium-ion batteries(SIBs) due to their high theoretical specific capacity and excellent electrical conductivity.However,they still suffer from volume distortion,structural collapse,and ionic conduction interruption upon cycling.Herein,a hierarchical array-like nanofiber structure was designed to address these limitations by combining architecture engineering and anion tuning strategy,in which SbPO_(4-x) with oxygen vacancy nanosheet arrays are anchored on the surface of interwoven carbon nanofibers(SbPO_(4-x)@CNFs).In particular,bulky PO_(4)^(3-) anions mitigate the large volume distortion and generate Na_(3)PO_(4) with high ionic conductivity,collectively improving cyclic stability and ionic transport efficiency.The abundant oxygen vacancies substantially boost the intrinsic electronic conductivity of SbPO_4,further accelerating the reaction dynamics.In addition,hierarchical fibrous structures provide abundant active sites,construct efficient conducting networks,and enhance the electron/ion transport capacity.Benefiting from the advanced structural design,the SbPO_(4-x)@CNFs electrodes exhibit outstanding cycling stability(1000 cycles at 1.0 A g^(-1) with capacity decay of 0.05% per cycle) and rapid sodium storage performance(293.8 mA h g^(-1) at 5.0 A g^(-1)).Importantly,systematic in-/ex-situ techniques have revealed the "multi-step conversion-alloying" reaction process and the "battery-capacitor dual-mode" sodium-storage mechanism.This work provides valuable insights into the design of anode materials for advanced SIBs with elevated stability and superior rate performance.

High-efficiency sodium storage of Co_(0.85)Se/WSe_(2) encapsulated in N-doped carbon polyhedron via vacancy and heterojunction engineering

With the advantage of fast charge transfer,heterojunction engineering is identified as a viable method to reinforce the anodes'sodium storage performance.Also,vacancies can effectively strengthen the Na+adsorption ability and provide extra active sites for Na+adsorption.However,their synchronous engineering is rarely reported.Herein,a hybrid of Co_(0.85)Se/WSe_(2) heterostructure with Se vacancies and N-doped carbon polyhedron(CoWSe/NCP)has been fabricated for the first time via a hydrothermal and subsequent selenization strategy.Spherical aberration-corrected transmission electron microscopy confirms the phase interface of the Co_(0.85)Se/WSe_(2) heterostructure and the existence of Se vacancies.Density functional theory simulations reveal the accelerated charge transfer and enhanced Na+adsorption ability,which are contributed by the Co_(0.85)Se/WSe_(2) heterostructure and Se vacancies,respectively.As expected,the CoWSe/NCP anode in sodium-ion battery achieves outstanding rate capability(339.6 mAh g^(−1) at 20 A g^(−1)),outperforming almost all Co/W-based selenides.

Aerodynamic/stealth design of S-duct inlet based on discrete adjoint method

It is a major challenge for the airframe-inlet design of modern combat aircrafts,as the flow and electromagnetic wave propagation in the inlet of stealth aircraft are very complex.In this study,an aerodynamic/stealth optimization design method for an S-duct inlet is proposed.The upwind scheme is introduced to the aerodynamic adjoint equation to resolve the shock wave and flow separation.The multilevel fast multipole algorithm(MLFMA)is utilized for the stealth adjoint equation.A dorsal S-duct inlet of flying wing layout is optimized to improve the aerodynamic and stealth characteristics.Both the aerodynamic and stealth characteristics of the inlet are effectively improved.Finally,the optimization results are analyzed,and it shows that the main contradiction between aerodynamic characteristics and stealth characteristics is the centerline and crosssectional area.The S-duct is smoothed,and the cross-sectional area is increased to improve the aerodynamic characteristics,while it is completely opposite for the stealth design.The radar cross section(RCS)is reduced by phase cancelation for low frequency conditions.The method is suitable for the aerodynamic/stealth design of the aircraft airframe-inlet system.

Improved observation of colonized roots reveals the regulation of arbuscule development and senescence by drought stress in the arbuscular mycorrhizae of citrus

Citrus is the typical mycorrhizal fruit tree species establishing symbiosis with arbuscular mycorrhizal (AM) fungi. However, arbuscule development and senescence in colonized citrus roots, especially in response to drought stress, remain unclear, which is mainly due to the difficulty in clearing and staining lignified roots with the conventional method. Here, we improved the observation of colonized roots of citrus plants with the sectioning method, which enabled the clear observation of AM fungal structures. Furthermore, we investigated the effects of one week of drought stress on arbuscule development and senescence with the sectioning method. Microscopy observations indicated that drought stress significantly decreased mycorrhizal colonization (F%and M%) although it did not affect plant growth performance. Fluorescence probes (WGA 488 and/or Nile red) revealed that drought stress inhibited arbuscule development by increasing the percentage of arbuscules at the early stage and decreasing the percentages of arbuscules at the midterm and mature stages. Meanwhile, drought stress accelerated arbuscule senescence, which was characterized by the increased accumulation of neutral lipids. Overall, the sectioning method developed in this study enables the in-depth investigation of arbuscule status, and drought stress can inhibit arbuscule development but accelerate arbuscule senescence in the colonized roots of citrus plants. This study paves the way to elaborately dissecting the arbuscule dynamics in the roots of fruit tree species in response to diverse abiotic stresses.

Improving hydrogen storage thermodynamics and kinetics of Ce-Mg-Ni-based alloy by mechanical milling with TiF_(3)

Mg-based hydrides are too stable and the kinetics of hydrogen absorption and desorption is not satisfactory.An efficient way to improve these shortcomings is to employ reactive ball milling to synthesize the nanocomposite materials of Mg and additives.In this experiment,TiF_(3)was selected as an additive,and the mechanical milling method was employed to prepare the experimental alloys.The alloys used in this experiment were the as-cast Ce_(5)Mg_(85)Ni_(10),as-milled Ce_(5)Mg_(85)Ni_(10)and Ce_(5)Mg_(85)Ni_(10)+3 wt.%TiF3.The phase transformation,structural evolution,isothermal and non-isothermal hydrogenation and dehydrogenation performances of the alloys were inspected by XRD,SEM,TEM,Sievert apparatus,DSC and TGA.It revealed that nanocrystalline appeared in the as-milled samples.Compared with the as-cast alloy,ball milling made the particle dimension and grain size decrease dramatically and the defect density increase significantly.The addition of TiF_(3)made the surface of ball milling alloy particles markedly coarser and more irregular.Ball milling and adding TiF_(3)distinctly improved the activation and kinetics of the alloys.Moreover,ball milling along with TiF_(3)can decrease the onset dehydrogenation temperature of Mg-based hydrides and slightly ameliorate their thermodynamics.

Effect of slow shot speed on externally solidified crystal,porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy

The effect of slow shot speed on externally solidified crystal(ESC),porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy(OM),scanning electron microscopy(SEM)and laboratory computed tomography(CT).Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when compared to the AlSi10MnMg alloy.The AlSi9MnMoV alloy,which was designed with trace multicomponent additions,displays a notable grain refining effect in comparison to the AlSi10MnMg alloy.Refining elements Ti,Zr,V,Nb,B promote heterogeneous nucleation and reduce the grain size of primaryα-Al.At a lower slow shot speed,the large ESCs are easier to form and gather,developing into the dendrite net and net-shrinkage.With an increase in slow shot speed,the size and number of ESCs and porosities significantly reduce.In addition,the distribution of ESCs is more dispersed and the net-shrinkage disappears.The tensile property is greatly improved by adopting a higher slow shot speed.The ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa(increased by 11.52%),and the elongation is enhanced from 3.72%to 6.34%(increased by 70.52%).