土埋条件下生物基锦纶56与锦纶6纤维的老化行为

为探究生物基锦纶56与锦纶6纤维在土壤填埋条件下是否会发生老化甚至降解,研究了土壤填埋时间、水分输入量和活性污泥含量对织物性能的影响。结果表明,在室温、不含活性污泥的土壤中填埋老化40周后,生物基锦纶56织物降强率小于15%;在室温、含50%活性污泥和0.5 L/d水分输入量的条件下,生物基锦纶56织物在土埋16周后强力下降约35%,进一步增加土埋时间(到40周)、活性污泥含量和输水量,织物强力不再降低。老化后纤维表面出现明显的刻蚀和凹陷,结晶度增加了3%~6%,表明老化过程主要发生在纤维的无定形区。石油基锦纶6织物在相同实验条件下,强力下降均低于9%,表明生物基锦纶56纤维更容易在土埋条件下发生老化现象。

助力火箭,推动梦想——神秘的助推剂

生存在古丝绸之路上河西走廊的朱雀家族成立了蓝箭基地,一直在探索环保、经济和安全的助推剂。小朱雀来参观,了解了多种液体推进剂,有推力巨大但容易积碳的液氧煤油、环保但耗能的液氧液氢、稳定但有毒性的偏二甲肼和四氧化二氮,最后他们了解到由蓝箭基地发射的朱雀二号运载火箭是全球首枚以液氧甲烷为推进剂的火箭。甲烷有丰富的储量、温和的储存条件和运输安全性、燃烧充分而且产物无污染,在未来有更广阔的用途。

基于最新势能面的C(^(1)D)+H_(2)反应的环聚合分子动力学研究

本文利用环聚合分子动力学方法对C(^(1)D)+H_(2)反应开展了详细的理论研究.计算中使用了最近构建的Zhang-Ma-Bian(ZMB)从头算势能面,该势能面对锥形交叉附近区域以及范德华区域均有精确的描述.环聚合分子动力学计算得到的热反应速率常数与最新实验值吻合很好.与前人计算结果比较,发现在a^(1)A’电子基态的ZMB-a势能面上获得的反应速率常数远大于前人构建的RKHS势能面上的结果,这是由于ZMB势能面上的范德华鞍具有与之前势能面上的范德华阱完全不同的动态学作用,表明环聚合分子动力学方法能够处理范德华作用引起的势能面拓扑结构所导致的动态学效应.本文还揭示了b^(1)A"电子激发态ZMB-b势能面以及量子效应对反应的重要性.

论家庭教育在儿童成长过程中的影响

家庭是组成社会的基本单位,家庭教育是教育的基石和开端。家庭教育的作用是学校教育无法替代的,家庭教育具有早期性、连续性和和全面性的特点,对儿童未来的发展和学习有着长远、乃至终生的影响,这种影响不会因为儿童进入学校和社会的而消失,家庭教育对于儿童的影响将会一直存在。这此对家庭氛围、家庭结构、教养方式三个方面展开探讨和分析,讨论现今家庭教育中存在的问题,探寻创造良好家庭教育影响的策略。

Carbon Nanosheets Encapsulated NiSb Nanoparticles as Advanced Anode Materials for Lithium-Ion Batteries

Metallic antimony(Sb) has been attracted much attentions as anode for lithium-ion batteries due to its high capacity.Nevertheless,the large volume expansion during the lithiation process leads to poor electrochemical performance,which seriously limits the practical application in lithium-ion batteries.Herein,NiSb nanoparticles encapsulated by carbon nanosheets have been developed via a facile strategy and as anode for lithium-ion batteries.In this attractive structure,the carbon nanosheets can effectively avoid volume change of NiSb nanoparticles and inhibit the direct contact of NiSb nanoparticles to the electrolyte during the lithiation/delithiation process.As a result,the NiSb/C nanosheets display an outstanding long cycling performance(405 mA h g-1 after 1000 cycles at 1.0 A g-1) and excellent rate capability(305 mA h g-1 at 2.0 A g-1) when application in lithium-ion batteries.

A commutation analytical model for quench protection of the CFETR central solenoid model coil

A central solenoid model coil will be set up to develop and verify the technique for the full-size central solenoid coil of the China Fusion Engineering Test Reactor.In case of quench and failures of superconducting coils,the quench protection(QP)system,which employs fuse-based commutation technology,is designed.This paper presents an analytical model to investigate the commutation process in the QP circuit.The model consists of the QP circuit equations,the breaker arc model,the fuse pre-arc model,and the fuse arc model.The model is employed in the whole commutation process including current transfer from breaker branch to the fuse branch model,then from fuse branch to the discharge resistor branch,and current decrease to zero in the discharge resistor.The experiment result verified the effectiveness of the presented model.The model might be helpful for design of the fuse and optimization of the commutation circuit.

EBI2 Regulating the Migration of B cells in T-dependent Antibody Responses

EBI2 is known as a kind of 7TM G protein-coupled receptors, and EBi2 gene is one of the most upregulated genes in Epstein-Barr virus （EBV） -infected lymphocytes. As a constitutively active receptor, EBI2 signals via Gai, and TM-II plays an important role in the signal transduct/on process. EBI2 is expressed mainly in mature, B cells and the expression level increases at the early stage of activation; subsequently, B cells are transferred into GC and the expression level is down-regulated. EBI2 can regulate independently and mediate synergistically the migration of B cell towards the extrafollicular areas and GC depending on chemo- kine receptors CXCR5 and CCR7 （EBII）. Differential expression of EBI2 receptor is conducive to accurate migration of B cells at different stages, thereby leading to appropriate irranunologic responses to T-dependent antigens. Recently, two research groups identified a specific oxysteml as the natural ligand for EBL2. Among all the oxysterols, 7α, 25-Dihydrexycholesteml （7a, 25-OHC） is the most effective ligand and activator, and EBI2-Oxysterol signal pathway plays an important role in adaptive immune responses. In addition, EBI2 is also closely related with specific kinds of autoimmune diseases, so it is considered as a negative regulator of the innate immune response in macrophages.

Complete biosynthesis of the phenylethanoid glycoside verbascoside

Verbascoside,which was first discovered in 1963,is a well-known phenylethanoid glycoside(PhG)that exhibits antioxidant,anti-inflammatory,antimicrobial,and neuroprotective activities and contributes to the therapeutic effects of many medicinal plants.However,the biosynthetic pathway of verbascoside remains to be fully elucidated.Here,we report the identification of two missing enzymes in the verbascoside biosynthesis pathway by transcriptome mining and in vitro enzymatic assays.Specifically,a BAHD acyltransferase(hydroxycinnamoyl-CoA:salidroside hydroxycinnamoyltransferase[SHCT])was shown to catalyze the regioselective acylation of salidroside to form osmanthuside A,and a CYP98 hydroxylase(osmanthuside B 3,30-hydroxylase[OBH])was shown to catalyze meta-hydroxylations of the p-coumaroyl and tyrosol moieties of osmanthuside B to complete the biosynthesis of verbascoside.Because SHCTs and OBHs are found in many Lamiales species that produce verbascoside,this pathway may be general.The findings from the study provide novel insights into the formation of caffeoyl and hydroxytyrosol moieties in natural product biosynthetic pathways.In addition,with the newly acquired enzymes,we achieved heterologous production of osmanthuside B,verbascoside,and ligupurpuroside B in Escherichia coli;this work lays a foundation for sustainable production of verbascoside and other PhGs in micro-organisms.

Dual-miRNA-Propelled Three-Dimensional DNA Walker for Highly Specific and Rapid Discrimination of Breast Cancer Cell Subtypes in Clinical Tissue Samples

Accurate discrimination of cell subtypes at the molecular level is especially important for cancer diagnosis,but no current method allows rapid and precise detection of breast cancer subtypes.Herein,we developed an elegant DNA walker for direct and rapid differentiation of breast cancer cell subtypes via detection of dual-miRNAs in clinical tissue samples.This DNA nanomachine can be specifically initiated by endogenous miR-21 and miR-31,and the sensitivity was dramatically improved due to the DNAzyme-mediated signal amplification.This DNA walker enabled rapid detection of double miRNA characteristics in different breast cell lines and also distinguished the fluctuations in a single cell.Applications of this DNAzyme-based nanomachine in vivo and in clinical samples were demonstrated for efficient detection of breast cancer subtypes,making the method generally applicable for precise management of cancers.

Aligning Fe_(2)O_(3)photo-sheets on TiO_(2)nanofibers with hydrophilic and aerophobic surface for boosting photoelectrochemical performance

Photoelectrochemical(PEC)nanomaterials are critical to producing clean oxygenation or value-added chemical production by utilizing sustainable solar energy,but are always limited by simultaneous integration of architectural engineering and electronic regulation in one structure.Directed by density functional theory(DFT)calculations and finite element analysis(FEA),the bioinspired ivy-like Fe_(2)O_(3)heterostructures with enriched oxygen defects on TiO_(2)nanofibers are designed for boosting PEC performances.Ivy-like Fe_(2)O_(3)photo-sheets remarkably enhanced the light harvesting by multiple light-mater interactions.The oxygen vacancies on Fe_(2)O_(3)photo-sheets could aid the photons catching and promote the reactivity at active sites.More importantly,demonstrated by a well-designed dynamic observation,the abundant tip-edges within ivy-like Fe_(2)O_(3)photo-sheets enabled the surface of heterostructure with hydrophilic and aerophobic properties.The functionalized surface allowed the rapid desorption of produced bubbles and thus ensured a high density of unoccupied active sites for electrolyte accessing.Featured by these attributes,the Fe_(2)O_(3)@TiO_(2)nanofibers delivered an excellent photocurrent of 40.8 mA/mg,high donor density(1.2×10^(18)cm^(−3)),and rapid oxygen production rate(1 mmol/(L∙h)).This work demonstrates a new strategy on nano-structural design for enhancing light-harvesting and making a hydrophilic/aerophobic surface on low-dimensional oxide nanomaterial,holding great potential on designing high-performance PEC devices for producing survival source gas,carbon-neutral fuel,and valuedchemicals.

Unraveling the amplified chiroptical responses of rylene-bladed quintuple[6]helicenes

Unraveling the key structural features to maximize the chiroptical properties is of significance for developing high-performance chiral materials.Here we present our first attempt to elucidate and understand the molecular design of excellent chiroptical properties via the combination of multiplicity and the alignment of subhelicenes.Two stereoisomeric PDI-bladed quintuple[6]helicenes,namely D_(5)-CRP and C_(2)-CRP,were revealed to show distinct spatial arrangements of subhelicenes.Circular dichroism(CD)spectra showed that the Cotton effects(Δε)are reaching 1,412 mol-1L cm-1for D_(5)-CRP and 669 mol^(-1)L cm^(-1)for C_(2)-CRP in the visible spectrum.The greatly amplifiedΔεrelative to the smaller analogue NPDH arises from the circular annulation of helicenes and high molecular symmetry that could significantly regulate the transition dipole moments and thereby make them tend to be(anti)parallel,as supported by TDDFT calculations for the rotatory strength(R).Consequently,the maximal dissymmetry factors(|g_(abs)|and|g_(lum)|)of this kind of chiral molecular carbon imides were estimated to be up to 0.021 and 0.012,respectively.This study provides a deep insight into the chiroptical properties of complicated chiral systems.

Axially N-Embedded Quasi-Carbon Nanohoops with Multioxidation States

The incorporation of heteroatoms into carbon nanohoops can significantly overcome aromatic stabilization energy and enrich their physicochemical properties depending on the positions and numbers of the doped atoms.Utilizing a V-shaped dipyreneo[c,e]dihydrophenazine as the building block,herein we report a novel kind of axially N-embedded quasi-carbon nanohoops by integratingπ-extended dihydropyrazine and para-phenylene subunits.Singlecrystal X-ray diffraction analyses revealed that their geometrical structures varied from droplet-shaped geometry for DPP-M and suppressed elliptical cross-section configuration for DPP-D to triangularly prismatic configuration for DPP-T.Spectroscopic measurements confirmed rich electronic properties,especially multioxidation behaviors due to the embedding of graphitic-N atoms,which are not observed in carbonaceous nanohoops and other analogs.Further investigations,including electron spin resonance spectroscopy,theoretical calculations,and single-crystal structure analyses,on the oxidized species of both DPP-D and DPP-T demonstrated their tunable open-shell ground states for the dications.This work provides a new synthetic strategy to axially N-embedded quasi-carbon nanohoops and gives insights into the design of structure-precise segments of graphitic-N-doped single-walled carbon nanotubes.

Hybrid Multi-Infeed Interaction Factor Calculation Method Considering Voltage Regulation Control Characteristics of Voltage Source Converter

Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluate its influence on the voltage interaction between VSC-HVDC and line commutated converter based high voltage direct current(LCC-HVDC),this paper proposes a hybrid multi-infeed interaction factor(HMIIF)calculation method considering the voltage regulation control characteristics of VSC-HVDC.Firstly,for a hybrid multi-infeed high voltage direct current system,an additional equivalent operating admittance matrix is constructed to characterize HVDC equipment characteristics under small disturbance.Secondly,based on the characteristic curve between the reactive power and the voltage of a certain VSC-HVDC project,the additional equivalent operating admittance of VSC-HVDC is derived.The additional equivalent operating admittance matrix calculation method is proposed.Thirdly,the equivalent bus impedance matrix is obtained by modifying the alternating current(AC)system admittance matrix with the additional equivalent operating admittance matrix.On this basis,the HMIIF calculation method based on the equivalent bus impedance ratio is proposed.Finally,the effectiveness of the proposed method is verified in a hybrid dual-infeed high voltage direct current system constructed in Power Systems Computer Aided Design(PSCAD),and the influence of voltage regulation control on HMIIF is analyzed.

A DC Grid Benchmark Model for Studies of Interconnection of Power Systems

Reducing carbon emissions in the power sector is critical for transitioning to a sustainable and low-carbon future.Estimating carbon efficiency of demand side response(DSR)in the power system is an important step towards realizing potential environmental benefits.Marginal emission factor(MEF)is an effective tool for estimating incremental changes in carbon emissions as a result of a change in demand.However,estimation methods currently used for evaluating MEF can be improved upon,specifically,by factoring in the ramp-rate constraint of generators in the fuel cost based merit order dispatch.In this paper is described a new method for MEF assessment under ramp-rate constraints;the method is then compared with two conventional estimations in a British power system.Three fuel price scenarios are used to conduct a sensitivity analysis of MEFs to fuel prices.Conclusions are drawn that can pave the way for future improvements in estimating MEF in power systems.

HVDC grid test models for different application scenarios and load flow studies

High Voltage Direct Current(HVDC) grids are the most effective solutions for collection, integration and transmission of large scale remote renewable resources to load centers. A HVDC grid test model can provide a common reference and study platform for researchers to compare the performance and characteristics of a DC grid with different DC control functions and protection strategies. It can also provide reference cases for testing of simulators and digital programs. This paper proposes a comprehensive HVDC grid test model and the associated four sub test models for system studies to meet the research purposes and requirements for different DC grid application scenarios. The design concept, topologies, configurations and functions of the test models are described in detail and their basic system data for load flow studies are provided. Finally load flow simulation studies with PSS/E(Power System Simulator/Engineering) program for each of the models are undertaken and the corresponding results are presented and analyzed in the paper.

Study of Oxygen Vacancies on Different Facets of Anatase TiO2

Anatase TiO2 samples with different ratios of {101} to {001} facets were prepared with hydrothermal method and further treated under three specific calcination atmospheres (air,H2,N2).The characterization results indicate that {001} facets may generate more oxygen vacancies and more Ti3+ species than {101} facets.

Two-Dimension(2D) Cu-MOFs/aptamer Nanoprobe for In Situ ATP Imaging in Living Cells

Monitoring the intracellular adenosine triphosphate(ATP)level is vital for elaborating its function in physiological states.However,the intracellular fluorescence sensing of ATP using ATP aptamer remains difficult owing to non-target displacement and susceptibility toward enzymatic degradation.Herein,by combining 2D Cu-MOF nanosheets and FAM labelled ATP aptamer,we developed a fluorescent Cu-MOFs/aptamer nanoprobe to image and sense intracellular ATP.This nanoprobe reveals a very low fluorescence intensity because of the excellent quenching efficiency of 2D Cu-MOF nanosheets.The presence of ATP was capable to dissociate the FAM-aptamer from Cu-MOF nanosheets and resulted in an intense fluorescence signal.The Cu-MOFs/aptamer nanoprobe enables highly sensitive and selective measurement of ATP level ranging from 10μM to 800μM with a detection limit of 4.24μM.This nanosystem also further realized in situ detection of the undulation of ATP trigged by drug stimulation,depending on the selective delivery of the nanoprobe and attractive capability of resisting nonspecific displacement.The constructed nanoprobe may supply a potential platform in clinical diagnostics and biological studies.

Axial compression tests and numerical simulation of steel reinforced recycled concrete short columns confined by carbon fiber reinforced plastics strips

To research the axial compression behavior of steel reinforced recycled concrete(SRRC)short columns confined by carbon fiber reinforced plastics(CFRP)strips,nine scaled specimens of SRRC short columns were fabricated and tested under axial compression loading.Subsequently,the failure process and failure modes were observed,and load-displacement curves as well as the strain of various materials were analyzed.The effects on the substitution percentage of recycled coarse aggregate(RCA),width of CFRP strips,spacing of CFRP strips and strength of recycled aggregate concrete(RAC)on the axial compression properties of columns were also analyzed in the experimental investigation.Furthermore,the finite element model of columns which can consider the adverse influence of RCA and the constraint effect of CFRP strips was founded by ABAQUS software and the nonlinear parameter analysis of columns was also implemented in this study.The results show that the first to reach the yield state was the profile steel in the columns,then the longitudinal rebars and stirrups yielded successively,and finally RAC was crushed as well as the CFRP strips was also broken.The replacement rate of RCA has little effect on the columns,and with the substitution rate of RCA from 0 to 100%,the bearing capacity of columns decreased by only 4.8%.Increasing the CFRP strips width or decreasing the CFRP strips spacing could enhance the axial bearing capacity of columns,the maximum increase was 10.5%or 11.4%,and the ductility of columns was significantly enhanced.Obviously,CFRP strips are conducive to enhance the axial bearing capacity and deformation capacity of columns.On this basis,considering the restraint effect of CFRP strips and the adverse effects of RCA,the revised formulas for calculating the axial bearing capacity of SRRC short columns confined by CFRP strips were proposed.

利用微波辅助[3+3]环化反应合成稠合吡啶衍生物

报道了一类新型的微波辅助对甲基苯磺酸促进的[3+3]环化反应.利用烯胺酮或烯胺内酯可作为1,3-双亲核试剂及炔丙醇可作为1,3-双亲电试剂的特性,使其在微波辐射及对甲苯磺酸促进条件下于冰醋酸中在70℃反应,实现了[3+3]环化反应,分别区域选择性地合成了2,2-二芳基取代四氢喹啉-5(1H)-酮衍生物和2,2-二芳基取代二氢呋喃并[3,4-b]吡啶-5-酮衍生物,产率良好.该反应利用微波合成技术促使反应,在短时间内完成(30 min),唯一副产物为水.此外,该方法具有原料简单易得、操作简单及底物普适性广等优点,从而为具有潜在应用价值的稠合吡啶骨架的构建提供了一种绿色、经济且高效的合成策略,符合绿色化学理念.

Enhancement of hydrogen production and energy recovery through electro-fermentation from the dark fermentation effluent of food waste

To enhance hydrogen production efficiency and energy recovery,a sequential dark fermentation and microbial electrochemical cell(MEC)process was evaluated for hydrogen production from food waste.The hydrogen production,electrochemical performance and microbial community dynamics were investigated during startup of the MEC that was inoculated with different sludges.Results suggest that biogas production rates and hydrogen proportions were 0.83 L/L d and 92.58%,respectively,using anaerobic digested sludge,which is higher than that of the anaerobic granular sludge(0.55 L/L d and 86.21%).The microbial community were predominated by bacterial genus Acetobacterium,Geobacter,Desulfovibrio,and archaeal genus Methanobrevibacter in electrode biofilms and the community structure was relatively stable both in anode and cathode.The sequential system obtained a 53.8% energy recovery rate and enhanced soluble chemical oxygen demand(sCOD)removal rate of 44.3%.This research demonstrated an important approach to utilize dark fermentation effluent to maximize the conversion of fermentation byproducts into hydrogen.