CO_(2) mineralization by typical industrial solid wastes for preparing ultrafine CaCO_(3): A review

Mineral carbonation is a promising CO_(2) sequestration strategy that can utilize industrial wastes to convert CO_(2) into high-value CaCO_(3).This review summarizes the advancements in CO_(2) mineralization using typical industrial wastes to prepare ultrafine CaCO_(3).This work surveys the mechanisms of CO_(2) mineralization using these wastes and its capacities to synthesize CaCO_(3),evaluates the effects of carbonation pathways and operating parameters on the preparation of CaCO_(3),analyzes the current industrial application status and economics of this technology.Due to the large amount of impurities in solid wastes,the purity of CaCO_(3) prepared by indirect methods is greater than that prepared by direct methods.Crystalline CaCO_(3) includes three polymorphs.The polymorph of CaCO_(3) synthesized by carbonation process is determined the combined effects of various factors.These parameters essentially impact the nucleation and growth of CaCO_(3) by altering the CO_(2) supersaturation in the reaction system and the surface energy of CaCO_(3) grains.Increasing the initial pH of the solution and the CO_(2)flow rate favors the formation of vaterite,but calcite is formed under excessively high pH.Vaterite formation is favored at lower temperatures and residence time.With increased temperature and prolonged residence time,it passes through aragonite metastable phase and eventually transforms into calcite.Moreover,polymorph modifiers can decrease the surface energy of CaCO_(3) grains,facilitating the synthesis of vaterite.However,the large-scale application of this technology still faces many problems,including high costs,high energy consumption,low calcium leaching rate,low carbonation efficiency,and low product yield.Therefore,it is necessary to investigate ways to accelerate carbonation,optimize operating parameters,develop cost-effective agents,and understand the kinetics of CaCO_(3) nucleation and crystallization to obtain products with specific crystal forms.Furthermore,more studies on life cycle assessment(LCA)should be conducted to fully confirm the feasibility of the developed technologies.

Silicon Mitigates Aluminum Toxicity of Tartary Buckwheat by Regulating Antioxidant Systems

Aluminum (Al) toxicity is a considerable factor limiting crop yield and biomass in acidic soil. Tartary buckwheatgrowing in acidic soil may suffer from Al poisoning. Here, we investigated the influence of Al stress on the growthof tartary buckwheat seedling roots, and the alleviation of Al stress by silicon (Si), as has been demonstrated inmany crops. Under Al stress, root growth (total root length, primary root length, root tips, root surface area, androot volume) was significantly inhibited, and Al and malondialdehyde (MDA) accumulated in the root tips. At thesame time, catalase (CAT) and ascorbate peroxidase activities, polyphenols, flavonoids, and 1,1-diphenyl-2-picrylhydrazyl(DPPH) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free-radical scavenging abilitywere significantly decreased. After the application of Si, root growth, Al accumulation, and oxidative damage wereimproved. Compared to Al-treated seedlings, the contents of ·O2− and MDA decreased by 29.39% and 25.22%,respectively. This was associated with Si-induced increases in peroxidase and CAT enzyme activity, flavonoidcompounds, and free-radical scavenging (DPPH and ABTS). The application of Si therefore has positive effectson Al toxicity in tartary buckwheat roots by reducing Al accumulation in the roots and maintaining oxidationhomeostasis.

Growth,ROS Markers,Antioxidant Enzymes,Osmotic Regulators and Metabolic Changes in Tartary Buckwheat Subjected to Short Drought

Tartary buckwheat(Fagopyrum tataricum)is an important pseudocereal feed crop with medicinal and nutritional value.Drought is one of the main causes of reduced growth and yield in these plants.We investigated the growth,physiological,and metabolic responses of the widely promoted Tartary buckwheat variety Chuan Qiao No.1 to polyethylene glycol(PEG)-mediated drought stress.Drought significantly decreased shoot length,shoot biomass and relative water content.Root length,malondialdehyde content,electrolyte leakage,activities of superoxide dismutase,peroxidase,catalase and amylase,and contents of soluble sugar,soluble protein and proline were increased by PEG-mediated drought.Untargeted metabolomics analysis identified 32 core metabolites in seedlings subjected to PEG-mediated drought,16 of which increased—including quercetin,isovitexin,cyanidin 3-O-beta-D-glucoside,L-arginine,and glycerophosphocholine,while the other 16 decreased—including 3-methoxytyramine,2,6-diaminopimelic acid,citric acid,UDP-alpha-D-glucose,adenosine,keto-D-fructose.The 32 core metabolites were enriched in 29 metabolic pathways,including lysine biosynthesis,citrate(TCA)cycle,anthocyanin biosynthesis,and aminoacyl-tRNA biosynthesis.Among them,taurine and hypotaurine metabolism,flavor and flavor biosynthesis,indole alkaline biosynthesis,and alanine,aspartate and glutamate metabolism were the four main metabolic pathways affected by drought.Our findings provide new insights into the physiological and metabolic response mechanisms of Tartary buckwheat to drought stress.

A pH-sensitive supramolecular nanosystem with chlorin e6 and triptolide co-delivery for chemo-photodynamic combination therapy

The combination of Ce6,an acknowledged photosensitizer,and TPL,a natural anticancer agent,has been demonstrated as a useful strategy to reinforce the tumor growth suppression,as well as decrease the systemic side effects compared with their monotherapy.However,in view of the optimal chemo-photodynamic combination efficiency,there is still short of the feasible nanovehicle to steadily co-deliver Ce6 and TPL,and stimuli-responsively burst release drugs in tumor site.Herein,we described the synergistic antitumor performance of a pH-sensitive supramolecular nanosystem,mediated by the host–guest complexing betweenβ-CD and acid pH-responsive amphiphilic co-polymer mPEG-PBAE-mPEG,showing the shell–core structural micelles with the tightβ-CD layer coating.Both Ce6 and TPLwere facilely co-loaded into the spherical supramolecular NPs(TPL+Ce6/NPs)by one-step nanoprecipitation method,with an ideal particle size(156.0 nm),acid pH-responsive drug release profile,and enhanced cellular internalization capacity.In view of the combination benefit of photodynamic therapy and chemotherapy,as well as co-encapsulation in the fabricated pH-sensitive supramolecular NPs,TPL+Ce6/NPs exhibited significant efficacy to suppress cellular proliferation,boost ROS level,lower MMP,and promote cellular apoptosis in vitro.Particularly,fluorescence imaging revealed that TPL+Ce6/NPs preferentially accumulated in the tumor tissue area,with higher intensity than that of free Ce6.As expected,upon 650-nm laser irradiation,TPL+Ce6/NPs exhibited a cascade of amplified synergistic chemo-photodynamic therapeutic benefits to suppress tumor progression in both hepatoma H22 tumor-bearingmice and B16 tumor-bearingmice.More importantly,lower systemic toxicitywas found in the tumor-bearingmice treated with TPL+Ce6/NPs.Overall,the designed supramolecular TPL+Ce6/NPs provided a promising alternative approach for chemo-photodynamic therapy in tumor treatment.

Molecular dynamics simulations of the interaction between OH radicals in plasma with poly-β-1–6-N-acetylglucosamine

Cold atmospheric plasma shows a satisfactory ability to inactivate bacterial biofilms that are difficult to remove using conventional methods in some cases. However, the researches on the inactivation mechanism are not quite sufficient. Poly-β-1–6-N-acetylglucosamine(PNAG),which is one of the important components in some biofilms, was used as the research subject,and the related mechanism of action triggered by different concentrations of the OH in plasma was studied using reactive molecular dynamics simulations. The results showed that OH radicals could not only trigger the hydrogen abstraction reaction leading to cleavage of the PNAG molecular structure, but undergo an OH addition reaction with PNAG molecules. New reaction pathways appeared in the simulations as the OH concentration increased, but the reaction efficiency first increased and then decreased. The simulation study in this paper could, to some extent, help elucidate the microscopic mechanism of the interaction between OH radicals in plasma and bacterial biofilms at the atomic level.

基于上转换纳米粒子的低损伤神经界面技术

光遗传技术能够实现对特定类型神经元的高时间分辨调控。过去几年,光遗传技术在神经环路的结构与功能研究中得到了广泛应用,并且在神经疾病治疗领域具有良好的应用前景。目前光遗传常用光敏蛋白的激发波长位于可见光波段。可见光的组织穿透性差,很难通过组织外照射来调控动物大脑深部的神经元电活动,因此极大地限制了光遗传技术的应用。上转换纳米粒子可以将组织穿透性好的近红外光转换成可见光激活光敏蛋白,从而可以实现可见光的远程、低损伤递送。近几年来,基于上转换纳米粒子的光遗传技术得到了迅速发展。本文将总结基于上转换纳米粒子的光遗传技术的研究现状及技术瓶颈,并且结合柔性神经电极技术的发展,对构建可以同时调控与检测活体大脑电活动的低损伤、双向神经界面进行了展望。

Investigation of non-thermal atmospheric plasma for the degradation of avermectin solution

Increasing concern with regard to food safety in the presence of pesticide residues(PRs) on the surface of agricultural products has resulted in the rapid development of practical degrading technologies for corresponding PRs. In this paper, an unconventional method of degrading pesticides, non-thermal atmospheric plasma(NTAP), was proposed to degrade the avermectin(AVM) in aqueous solution. Optical emission spectroscopy shows that NTAP, consisting of filamentary streamers, contains a variety of reactive oxygen species(ROS) that may interact with AVM. The high-performance liquid chromatography(HPLC)-MS/MS results indicate that the efficiency of AVM degradation seriously depends on multiple operation parameters of the NTAP,including the applied voltage, treatment time and gas flow rate. The maximum degradation rate of AVM was observed to be 97.47% after 240 s exposure under NTAP with an applied voltage of 18 kV and gas flow rate of 1 l min-1. Molecular dynamics simulation based on a reactive force field for the interaction between O(ground state atomic oxygen) and AVM was performed to analyze the underpinning mechanisms. The simulation result shows the possible pathways of the NTAPgenerated O degrading AVM by destroying the glycosyl group or fracturing the ester group.

Evaluation of Natural Radioactivity in Marine Sand Deposits from Offshore China

Natural radioactivity is very important for the assessment of the marine sand property and usability. By using gamma spectrometry, the concentration of the natural radionuclides 226Ra, 232Th and 40K have been measured in marine sand deposits from Liaodong Bay (LDB), North Yellow Sea (NYS), Zhoushan area (ZS), Taiwan Shoal (TS) and Pearl River Mouth (PR), offshore China, which are potential marine sand mining areas. The radiation activity equivalent (Raeq), indoor gamma absorbed dose rate (DR), annual effective dose (HR), alpha index (Ia), gamma index (Ig), external radiation hazard index (Hex), internal radiation hazard index (Hin), representative level index (RLI), excess lifetime cancer risk (ELCR) and annual gonadal dose equivalent (AGDE) associated with the natural radionuclides are calculated to assess the radiation hazard of the natural radioactivity in the marine sands offshore China. From the analysis, it is found that these marine sands are safe for the constructions. The Pearson correlation coefficient reveals that the 226Ra distribution in the marine sands offshore China is controlled by the variation of the 40K concentration. Principal component analysis (PCA) yields a two-component representation of the entire data from the marine sands, wherein 98.22% of the total variance is explained. Our results provide good baseline data to expand the database of radioactivity of building materials in China and all over the world.

Propofol Affects Different Human Brain Regions Depending on Depth of Sedation

Objective To investigate the effect of propofol on brain regions at different sedation levels and the association between changes in brain region activity and loss of consciousness using blood oxygen level-dependent functional magnetic resonance imaging(BOLD-f MRI) and bispectral index(BIS) monitoring.Methods Forty-eight participants were enrolled at Peking Union Medical College Hospital from October 2011 to March 2012 and randomly assigned to a mild or a deep sedation group using computergenerated random numbers.Preliminary tests were performed a week prior to scanning to determine target effect site concentrations based on BIS and concomitant Observer's Assessment of Alertness/Sedation scores while under propofol.Within one week of the preliminary tests where propofol dose-response was established,BOLD-f MRI was conducted to examine brain activation with the subject awake,and with propofol infusion at the sedation level.Results Mild propofol sedation inhibited left inferior parietal lobe activation.Deep sedation inhibited activation of the left insula,left superior temporal gyrus,and right middle temporal gyrus.Compared with mild sedation,deep propofol sedation inhibited activation of the left thalamus,precentral gyrus,anterior cingulate,and right basal nuclei.Conclusion Mild and deep propofol sedation are associated with inhibition of different brain regions,possibly explaining differences in the respective loss of consciousness processes.

Polysaccharide Elicitor from the Endophyte Bionectria sp.Fat6 Improves Growth of Tartary Buckwheat under Drought Stress

Drought can limit the growth and reduce the yield of crops,but the safe and effective bio-approach to improve the drought resistance of crops is very little.We conducted an experiment in which we monitored the effects of polysaccharide from the endophyte Bionectria sp.Fat6 on the growth of Tartary buckwheat(Fagopyrum tataricum(L.)Gaertn)seedlings under control and drought-stressed conditions by determining gas exchange,photosynthesis parameters,photosynthetic pigment contents,and metabolite accumulation.Results indicated that the polysaccharide from endophyte stimulated plant growth and increased the aboveground biomass,root mass,and root/shoot ratio of Tartary buckwheat.Application of the polysaccharide to drought-stressed plants resulted in a significant increase in the net photosynthetic rate,stomatal conductance,and transpiration rate of Tartary buckwheat and decreased the intercellular CO_(2) concentration.The contents of chlorophyll a,chlorophyll b,chlorophyll a+b,and carotenoids in leaves were higher in polysaccharide-treated seedlings than that in control.Polysaccharide notably increased the soluble protein and proline content and decreased the malondialdehyde content in Tartary buckwheat leaves.The endophytic polysaccharide may protect Tartary buckwheat against drought by improving leaf gas exchange and photosynthetic capacity,and altering concentrations of protective metabolites.Together,these changes may compensate for the negative impacts of drought stress on the growth of Tartary buckwheat.Thus,the polysaccharide from the endophyte Bionectria sp.Fat6 may be an effective biotic elicitor and a promising bio-approach to improve Tartary buckwheat production worldwide.

Identification of LRRC46 as a novel candidate gene for high myopia

High myopia(HM)is the primary cause of blindness,with the microstructural organization and composition of collagenous fibers in the cornea and sclera playing a crucial role in the biomechanical behavior of these tissues.In a previously reported myopic linkage region,MYP5(17q21-22),a potential candidate gene,LRRC46(c.C235T,p.Q79X),was identified in a large Han Chinese pedigree.LRRC46 is expressed in various eye tissues in humans and mice,including the retina,cornea,and sclera.In subsequent cell experiments,the mutation(c.C235T)decreased the expression of LRRC46 protein in human corneal epithelial cells(HCE-T).Further investigation revealed that Lrrc46^(-/-)mice(KO)exhibited a classical myopia phenotype.The thickness of the cornea and sclera in KO mice became thinner and more pronounced with age,the activity of limbal stem cells decreased,and microstructural changes were observed in the fibroblasts of the sclera and cornea.We performed RNA-seq on scleral and corneal tissues of KO and normal control wild-type(WT)mice,which indicated a significant downregulation of the collagen synthesis-related pathway(extracellular matrix,ECM)in KO mice.Subsequent in vitro studies further indicated that LRRC46,a member of the important LRR protein family,primarily affected the formation of collagens.This study suggested that LRRC46 is a novel candidate gene for HM,influencing collagen protein VⅢ(Col8a1)formation in the eye and gradually altering the biomechanical structure of the cornea and sclera,thereby promoting the occurrence and development of HM.

High-efficiency CO_(2) sequestration through direct aqueous carbonation of carbide slag: determination of carbonation reaction and optimization of operation parameters

Under the dual-carbon target, CO_(2) mineralization through solid wastes presents a mutually beneficial approach for permanent carbon emission reduction at a low material cost, while also enabling the resource utilization of these wastes. However, despite its potential, a comprehensive understanding about the effect of industrial solid waste properties and operating parameters on the carbonation process, and the mechanism of direct aqueous carbonation is still lacking. A series of experiments were conducted to compare the carbonation performance of fly ash, steel slag, and carbide slag. Subsequently, CO_(2) mineralization by carbide slag was systematically studied under various operating parameters due to its high CO_(2) sequestration capacity. Results showed the reactivity of CaO and Ca(OH)2 was higher than that of CaO·SiO_(2) and 2CaO·SiO_(2). Carbide slag demonstrated a sequestration capacity of 610.8 g CO_(2)/kg and carbonation efficiency ζCa of 62.04% under the conditions of 65 ℃, 1.5 MPa initial CO_(2) pressure, 15 mL/g liquid-to-solid ratio, and 200 r/min stirring speed. Moreover, the formation of carbonates was confirmed through XRD, SEM-EDS, TG, and FTIR. A mechanism analysis revealed that initially, the rate of the carbonation process was primarily controlled by the mass transfer of CO_(2) in the gas–liquid interface. However, the rate-determining step gradually shifted to the mass transfer of Ca2+ in the solid–liquid interface as the reaction time increased. This study lays the foundation for the large-scale implementation of CO_(2) sequestration through carbide slag carbonation.

Finite Element Simulation and Experimental Study on Vibration Characteristics of Converter Transformer Under DC Bias

To clarify the electromagnetic,vibration,and loss characteristics of the internal components of a converter transformer under DC bias conditions and their influencing mechanisms,a series of studies are conducted using the finite element method and model experiments.This paper quantifies the influence of different DC contents on the magnetic flux density,force,and displacement distribution characteristics of the iron core and winding and analyzes the internal relationship between various indicators.The inflection point of the DC bias coefficient on the vibration is obtained and the contribution mechanism of the different responses of the iron core and winding to this inflection point is explained.The value of the DC bias coefficient for changing the main vibration frequency is determined.When the DC bias coefficient is 1.0 and 1.5,the main frequency of vibration moves to the right to 250 Hz and 350 Hz.Based on the principle of similarity,a DC bias vibration experimental platform for converter transformers is developed,and DC bias magnetic experiments are conducted to verify the reliability of the simulation results.

激光雷达技术在动物生态学领域的研究进展

激光雷达(light detection and ranging,LiDAR)作为一门新兴的主动遥感技术,近年来由于在提取和反演森林参数水平上不断提高,被越来越多地应用于动物生态学研究中。本文通过整理和搜集国内外文献,对激光雷达的技术特点及其在森林参数提取和动物生境上的研究进展进行综述,指出当前基于LiDAR的森林参数反演算法主要服务于森林资源调查或林学研究,缺少对动物生态或生理意义相关的参数量化信息。目前该技术在国内的动物生态学方面的应用较少,尚未见文章发表。通过总结国外学者的研究,分别从动物生境选择与三维森林结构的关系、栖息地立体生境制图、生物多样性评估和物种分布模型预测三个方面综述了LiDAR在动物生态学研究中的应用现状。相比传统方法,LiDAR技术提供的高精度三维结构信息,能够显著提高动物生境质量的评估、生物多样性的监测水平和物种分布模型的评价精度,有利于从机理上加深对物种生境选择和集群过程的理解。但目前LiDAR技术的应用主要集中在对已知的生态关系研究,尤其是冠层结构与动物分布的关系,缺少对林下层生活的动物生境质量和生物多样性的监测和评估,同时很多有关动物生存和繁衍与立体生境的关系研究有待从LiDAR数据中进一步挖掘分析。未来应加强对森林林下层三维信息的提取,提高林下层动物生境质量和生物多样性的监测水平,同时建立适用于动物生态和生理意义相关的参数,为动物生境质量和生物多样性的评估提供标准的量化指标。

Oral colon-targeted mucoadhesive micelles with enzyme-responsive controlled release of curcumin for ulcerative colitis therapy

Although multitudinous nanoscale drug-delivery systems(DDSs)have been recommended to improve anti-ulcerative colitis(UC)outcomes,to enhance the mucoadhesion of nanosystems on the colon and specifically release the loaded drugs in response to the colon micro-environment would be critical factors.The application of curcumin(Cur),an acknowledged anti-UC phytochemical compound,for UC therapy requires more efficient nano-carriers to improve its therapeutic outcome.Herein,we developed the colon-targeted nano-micelles with mucoadhesive effect and Azo reductase-triggered drug release profiles for Cur delivery in UC treatment.Specifically,the amphiphilic block polymer containing the Azo-reductase sensitive linkage(PEG-Azo-PLGA),and catechol-modified TPGS(Cat-TPGS)were synthesized respectively.Based on the self-assembly of the mixed polymers,Cur-micelles(142.7±1.7 nm of average size,72.36%±1.54%of DEE)were obtained.Interestingly,the Cur-micelles exhibited the Azo-reductase sensitive particle dissociation and drug release,the enhanced cellular uptake and the prolonged retention on colonic mucosa,mediated by the strong mucoadhesion of catechol structure.Ultimately,Cur-micelles significantly mitigated colitis symptoms and accelerated colitis repair in DSS-treated mice by regulating the intestinal flora and the levels of pro-inflammatory factors(MPO,IL-6,IL-1β,and TNF-α)related to TLR4/MyD88/NF-κB signaling pathway.This work provides an effective drug delivery strategy for anti-UC drugs by oral administration.

A ratiometric fluorescent sensor for tracking Cu(Ⅰ) fluctuation in endoplasmic reticulum

A two-photon ratiometric fluorescent sensor for Cu^+ in endoplasmic reticulum(ER), CNSB, was developed via coumarin/ASBD integration based on FRET mechanism. In solution, CNSB shows reversible, highly-specific ratiometric response to Cu^+ .Moreover, CNSB exhibits suitable K_d value, suggesting the possibility of detecting Cu^+ in the living cells. The probe can enter the MCF-7 cells easily and specifically locates in the ER. The highly specific ratiometric response of CNSB toward Cu^+ in MCF-7 cells provides the sensor the capacity to visualize both exogenous and endogenous Cu^+ in the ER via fluorescence imaging.Next, CNSB was utilized to detect the fluctuation and distribution of Cu^+ under ER stress in MCF-7 cells, which confirmed directly the relationship between Cu^+ enhancement and ER stress. Meanwhile, the two-photon ability of coumarin facilitated the sensor to visualize Cu^+ fluctuation via two-photon fluorescence imaging. In addition, the spatial distribution of Cu^+ in the heart slice of the 14-day-old rat was demonstrated using CNSB. This study demonstrates the promising potential of CNSB in clarifying the Cu^+ -dependent signaling in the ER stress-related diseases.

石墨烯在神经电信号检测中的应用

神经电极是监测大脑活动的重要工具,在理解大脑运行机制和治疗神经系统疾病等领域发挥着重要作用。实现神经电极对神经电信号的长期稳定检测,构筑可靠的电极-神经界面是关键。传统的神经电极多采用刚性材料,与柔软的神经组织力学性能不匹配,限制了其对神经电信号的长期稳定记录。石墨烯是一种具有单原子层厚度的二维碳纳米材料,具有高的导电性、力学柔性和良好的生物相容性,可以与神经细胞/组织构筑稳定的电极-神经界面,从而实现神经电信号的长期稳定记录。本文梳理了石墨烯在神经电信号检测中的应用,包括石墨烯-细胞的相互作用及利用石墨烯神经电极进行体外和在体神经电信号的检测和记录等。最后,对石墨烯在神经电信号检测方面的未来发展方向进行了展望。

Mitochondria-localized iridium(Ⅲ) complexes with anthraquinone groups as effective photosensitizers for photodynamic therapy under hypoxia

Photodynamic therapy（PDT） is a potential way for the tumor treatment. However, it notably suffers the limitation of hypoxia in solid tumors. Thus, it is significant to develop effective photosensitizers which can exhibit excellent therapeutic performance under both normoxia and hypoxia. Herein, we reported four ionic iridium（III） complexes（Ir1–Ir4） with anthraquinone groups which can regulate their excited state energy levels effectively. Among them, the energy gap of Ir1 was between 1.63 and 2.21 eV, which can match well with that of O2, and the HOMO energy of Ir1 is less than-5.51 eV. Compared with Ir2–Ir4, the luminescent quantum efficiency of Ir1 was the highest. Particularly, Ir1 can specifically target the mitochondria of the tumor cells. Meanwhile, Ir1 showed high singlet oxygen quantum yields（ΦΔ） in both solutions and living cells with low cytotoxicity.The results of PDT experiments revealed that Ir1, as a photosensitizer, exhibited excellent therapeutic effect not only in normoxia but also in hypoxia condition. We believe that this work is meaningful for developing excellent PDT agents based on cyclometalated Ir（III） complexes via rational ligand modification.

Innovated Inertia Control of DFIG with Dynamic Rotor Speed Recovery

High wind power penetration(WPP)is challenging system frequency stability.As a countermeasure,virtual inertia controls are introduced,utilizing kinetic energy(KE)stored in wind turbine generators(WTGs)for frequency regulation.Without restoration,generation efficiency of WTGs will be degraded after inertia contribution.To counter this issue,we propose an inertia control scheme of a doubly fed induction generator(DFIG),aiming at achieving dynamic inertia recovery regarding both KE and DC link energy.An asymmetrical droop control,referred to as the rate of change of frequency(RoCoF),is proposed for KE management.The upper boundary of droop gain is extended to give full play to converters and is revised,considering the system frequency state,to counter positive feedback issues induced by reversible gain regulation,which is restricted by KE to ensure stable operations as well.The inertial DC energy needed to cooperate with KE control regarding countering small fluctuations,is improved with an orderly recovery behavior.Case studies are conducted under dynamic wind conditions and the results indicate that with our proposed scheme,the ability of dynamic inertia recovery can be obtained,bringing DFIG higher generation efficiency and more adequate operation margin for sustained regulation.Essentially,the inertial frequency response and fluctuation suppression ability is well maintained.

Palladium-catalysed stereoselective[3+2]annulation of vinylethylene carbonates and tryptanthrin-based ketones

The palladium-catalysed[3+2]annulation of vinylethylene carbonates(VECs)and ketones remains challenging in organic synthesis.Herein,we successfully achieved the[3+2]annulation of tryptanthrin-based ketones and VECs for the efficient synthesis of indoloquinazolinone derivatives with generally excellent yields and good diastereoselectivity.Notably,the asymmetric version of this[3+2]annulation can also be achieved by using a chiral spiroketal-based diphosphine ligand.In addition,preliminary biological studies reveal that some of the products exhibit promising antibacterial activity.