成分及加工工艺对8030铝合金电缆导体的影响综述

8030铝合金具有导电性能好、重量轻、抗蠕变性能强和延展性高等优点,是一种优良的导体,在输配电线路方面得到了广泛的应用。从导体材料成分和加工工艺两个方面综述了Cu、Fe、Mg、B和稀土元素(La、Ce、Yb、Er)以及拉拔工艺、退火工艺、挤压工艺等对8030铝合金导体微观结构和宏观性能的影响规律及机理。总结并提出了接头处导体连接工艺可能对8030铝合金电缆导体的影响,指出了未来可能的研究方向。

Influence of nitrogen status on fermentation performances of non-Saccharomyces yeasts:a review

Nitrogen,one of the most crucial nutrients present in grapes and musts,plays a key role in yeast activities during alcoholic fermentation.Such influences are imposed on yeast growth and fermentation performances including the formation of secondary metabolites.Saccharomyces cerevisiae,the main yeast responsible for fermentation,has been studied extensively regarding nitrogen impacts.On the other hand,a similar study for non-Saccharomyces yeasts,whose contributions to winemaking have gradually been acknowledged,remains to be fully explored,with a few studies being reported.This review starts by discussing nitrogen impacts on non-Saccharomyces yeast growth and fermentation kinetics in different case scenarios,then proceeds to summarize the nitrogen preferences of individual yeast strains with regulation mechanisms elucidated by recent studies.Detailed discussions on the influences on the production of volatile compounds and proposed pathways therein are made,followed by future work suggested as the final section.In summarizing the nitrogen impacts on non-Saccharomyces yeasts throughout alcoholic fermentation,this review will be helpful in obtaining a more comprehensive view on these non-conventional wine yeasts in terms of nutrient requirements and corresponding volatile production.Research gaps will therefore be elucidated for future research.

电力推进永磁同步电机的无传感器控制研究

为提高电力推进无传感器永磁同步电机的稳定性,基于两相旋转坐标系和电机矢量模型,提出一种改进的电机滑模观测器。为增强滑模观测器的抗干扰性能和控制精度,采用sigmoid函数作为滑模观测器开关函数,并引入模糊控制策略改进开关增益;然后采用ACO算法优化滑模观测器的可调参数。仿真结果表明,该改进滑模观测器可提高电力推进无传感器永磁同步电机对转速和转矩控制的稳定性,使d、q轴电流更平稳,提高永磁同步电机的转子位置估计精度,降低位置估计误差。

采用同步辐射小角X射线散射技术研究Al−Mg−Si合金的析出强化行为

研究Al−Mg−Si合金在等温时效过程中的析出强化行为及其对力学性能的影响。利用原位同步辐射小角X射线散射(SAXS)技术和透射电子显微镜(TEM)对纳米析出相及其结构参数(尺寸、体积分数和数密度)进行表征。结果表明,棒状β''析出相优先沿其纵向尺寸生长,但径向尺寸在时效5 h后达到峰值。如预测与测量的屈服强度和硬度结果所示,纳米析出相的尺寸和体积分数的增大与析出强化定量相关。SAXS为Ashby−Orowan模型提供了更可靠的输入参数,这有助于提高模型的预测精度和泛化能力。研究表明,随着时效时间的延长,Al−Mg−Si合金预测力学性能的演变与β''析出相的平均半径和体积分数有关。

响应面法优化水解制备柞蚕丝素肽及其性能

以柞蚕丝素蛋白为原料,用磷酸水解方法制备柞蚕丝素肽。在单因素实验基础上,通过响应面法优化制备工艺,考察各因素对柞蚕丝素肽回收率的影响,并对该工艺条件制备的样品进行了性能分析。结果表明:柞蚕丝素肽最佳水解工艺条件为:柞蚕丝素质量分数9.93%、水解温度91.11℃、水解时间5.44 h,理论回收率为70.34%,经检验实际回收率可以达到69%,与理论值基本相符,建立了响应面分析法优化的柞蚕丝素肽水解制备工艺。柞蚕丝素肽性能实验结果表明,样品具有良好的吸湿保湿性、防晒性及抑菌性,说明柞蚕丝素肽在天然护肤品开发方面具有良好的应用价值。

L-3-n-butylphthalide protects against vascular dementia via activation of the Akt kinase pathway

As a neuroprotective drug for the treatment of ischemic stroke, 3-n-butylphthalide, a celery seed ex- tract, has been approved by the State Food and Drug Administration of China as a clinical therapeutic drug for ischemic stroke patients. L-3-n-butylphthalide possesses significant efficacy in the treatment of acute ischemic stroke. The activated Akt kinase pathway can prevent the death of nerve cells and exhibit neuroprotective effects in the brain after stroke. This study provides the hypothesis that I-3-n- butylphthalide has a certain therapeutic effect on vascular dementia, and its mechanism depends on the activation of the Akt kinase pathway. A vascular dementia mouse model was established by cere- bral repetitive ischemia/reperfusion, and intragastrically administered I-3-n-butylphthalide daily for 28 consecutive days after ischemia/repedusion, or 7 consecutive days before ischemia/reperfusion. The Morris water maze test showed significant impairment of spatial learning and memory at 4 weeks after operation, but intragastric administration of I-3-n-butylphthalide, especially pretreatment with I-3-n- butylphthalide, significantly reversed these changes. Thionine staining and western blot analylsis showed that preventive and therapeutic application of I-3-n-butylphthalide can reduce loss of pyrami- dal neurons in the hippocampal CA1 region and alleviate nerve damage in mice with vascular demen- tia. In addition, phosphorylated Akt expression in hippocampal tissue increased significantly after I-3-n- butylphthalide treatment. Experimental findings demonstrate that I-3-n-butylphthalide has preventive and therapeutic effects on vascular dementia, and its mechanism may be mediated by upregulation of phosphorylated Akt in the hippocampus.

Unraveling the skatole biodegradation process in an enrichment consortium using integrated omics and culture-dependent strategies

3-Methylindole(skatole)is regarded as one of the most offensive compounds in odor emission.Biodegradation is feasible for skatole removal but the functional species and genes responsible for skatole degradation remain enigmatic.In this study,an efficient aerobic skatole-degrading consortium was obtained.Rhodococcus and Pseudomonas were identified as the two major and active populations by integrated metagenomic and metatranscriptomic analyses.Bioinformatic analyses indicated that the skatole downstream degradation wasmainly via the catechol pathway,and upstream degradation was likely catalyzed by the aromatic ring-hydroxylating oxygenase and flavin monooxygenase.Genome binning and gene analyses indicated that Pseudomonas,Pseudoclavibacter,and Raineyella should cooperate with Rhodococcus for the skatole degradation process.Moreover,a pure strain Rhodococcus sp.DMU1 was successfully obtained which could utilize skatole as the sole carbon source.Complete genome sequencing showed that strain DMU1 was the predominant population in the consortium.Further crude enzyme and RT-qPCR assays indicated that strain DMU1 degraded skatole through the catechol ortho-cleavage pathway.Collectively,our results suggested that synergistic degradation of skatole in the consortium should be performed by diverse bacteria with Rhodococcus as the primary degrader,and the degradation mainly proceeded via the catechol pathway.

Metal-free synthesis of pyridyl conjugated microporous polymers with tunable bandgaps for efficient visible-light-driven hydrogen evolution

Conjugated microporous polymers(CMPs) with tunable bandgaps have attracted increasing attention for photocatalytic hydrogen evolution. However, the synthesis of CMPs usually needs expensive metal-based catalysts. Herein, we report a metal-free synthetic route to fabricate pyridyl conjugated microporous polymers(PCMPs) via a condensed polymerization between aldehyde and aryl ketone monomers. The PCMPs show widely tunable specific surface areas(347–418 m^(2)/g), which were controlled via changing the used monomers. The PCMPs synthesized using monomers of dialdehyde and diacetylbenzene(diacetylpyridine) in the presence of pyridine exhibited the highest visible-light driven hydrogen evolution rate(9.56 μmol/h). These novel designed PCMPs provide wide adaptability to current materials designed for high-performance photocatalysts in different applications.

Particles in composite polymer electrolyte for solid-state lithium batteries:A review

Solid-state lithium batteries(SSLBs)have been identified as one kind of the most promising energy conversion and storage devices because of their safety,high energy density,and long cycling life.The development of solid-state electrolyte is vital to commercialize SSLBs.Composite polymer electrolyte(CPE),derived by compositing inorganic particles into solid polymer electrolyte has become the most practical species for SSLBs because it inherits the advantages of polymer electrolyte and simultaneously achieves enhanced ionic conductivity and mechanical properties.The characteristics of inorganic particles and their interaction with polymers strongly impact the performance of CPE,improving its ionic conductivity,mechanical properties,thermal and electrochemical stability,as well as interface compatibility with both electrodes.In this review,the effects of particle characteristics including its species,size,proportion,morphology on the ionic conductivity and mechanical properties of CPE are reviewed.Meanwhile,some novel composite strategies are also introduced including surface modification,hybridization,and alignment of particles in polymer matrices,as well as some new preparation methods of CPE.The interactions between particles and other components in CPE including polymer matrices or lithium salt are particularly focused herein to reveal the lithium conductive mechanism.Finally,a perspective on the direction of future CPE development for SSLBs is presented.

Experimental study on plasma jet deflection and energy extraction with MHD control

This paper presents an integrated research scheme for vector deflection and energy extraction in a gas plasma jet under Magneto-Hydrodynamic(MHD)control.A MHDcontrolled thrust-vector test rig was used to conduct the experimental research.A gas plasma was obtained by injecting ionization seeds of Cs2CO3 into the combustion chamber via artificially forced ionization.The effects of the gas temperature and ionization seed mass fraction on the plasma jet deflection and energy extraction were experimentally verified under an applied magnetic field.The experimental results were analyzed theoretically.The results showed that the deflection amplitude of the gas plasma jet and the extracted voltage signal intensity increased with increasing gas temperature and the ionization seed mass fraction.The extracted dynamic voltage signals proved that the ionization seeds of Cs2CO3 induced gas ionization at 1173 K.The experiment verified that it is feasible to simultaneously achieve jet deflection and extract energy under the action of an external magnetic field.

Consideration of climate change impacts will improve the efficiency of protected areas on the Qinghai-Tibet Plateau

The protection of migratory birds and their habitats is important to the ecological stability of the Qinghai-Tibet Plateau(QTP).Currently protected areas(PAs)were designed in accordance with species distribution patterns under current climatic conditions,thus ignoring climate change will lead to a decrease in the protection efficiency of PAs.In this study,using the flagship species Grus nigricollis,as an example,we used the maximum entropy(MaxEnt)model to simulate the distributions and conservation status of G.nigricollis and optimized the existing PA boundaries.The results showed that(1)suitable habitat-for G.nigricollis accounts for 12.48%of the QTP area,and the PAs established under current climatic conditions cover 17.84%of this suitable habitat area;(2)future climate changes will influence the distribution and quality of G.nigricollis habitats,and the average protection efficiency of the current PAs in four climatic scenarios will decrease from 17.84%to 15.31%;and(3)through optimization,the efficiency of existing PAs can be increased by 0.75 times and reach 28.37%,indicating PA planning must consider not only current climate conditions but also the effects of climate changes.Our results aim to address shortcomings in the conservation efficiency of PAs and provide an example for resolving mismatched PA boundaries and habitat changes for species.

Newton-Type Optimal Thresholding Algorithms for Sparse Optimization Problems

Sparse signals can be possibly reconstructed by an algorithm which merges a traditional nonlinear optimization method and a certain thresholding technique.Different from existing thresholding methods,a novel thresholding technique referred to as the optimal k-thresholding was recently proposed by Zhao(SIAM J Optim 30(1):31-55,2020).This technique simultaneously performs the minimization of an error metric for the problem and thresholding of the iterates generated by the classic gradient method.In this paper,we propose the so-called Newton-type optimal k-thresholding(NTOT)algorithm which is motivated by the appreciable performance of both Newton-type methods and the optimal k-thresholding technique for signal recovery.The guaranteed performance(including convergence)of the proposed algorithms is shown in terms of suitable choices of the algorithmic parameters and the restricted isometry property(RIP)of the sensing matrix which has been widely used in the analysis of compressive sensing algorithms.The simulation results based on synthetic signals indicate that the proposed algorithms are stable and efficient for signal recovery.

Metal-free Synthesis of Pyridyl Conjugated Microporous Polymers for Photocatalytic Hydrogen Evolution

Developing efficient,stable and sustainable photocatalysts for water splitting is one of the most significant methods for generating hydrogen.Conjugated microporous polymers,as a new type of organic semiconductor photocatalyst,have adjustable bandgaps and high specific surface areas,and can be synthesized using diverse methods.In this work,we report the design and synthesis of a series of pyridyl conjugated microporous polymers(PCMPs)utilizing polycondensation of aromatic aldehydes and aromatic ketones in the presence of ammonium acetate.PCMPs with different chemical structures were synthesized via adjusting monomers with different geometries and contents of nitrogen element,which could adjust the bandgap and photocatalytic performance.Photocatalytic hydrogen evolution rate(HER)up to 1198.9μmol·h^(-1)·g^(-1) was achieved on the optimized polymer with a specific surface area of 312 m^(2)·g^(-1) under UV-Vis light irradiation(A>320 nm).This metal-free synthetic method provides a new avenue to preparing an efficient photocatalyst for hydrogen evolution.

Low-cost Free-standing ferroelectric polymer films with high polarization produced via pressing-and-folding

Ferroelectric polymer poly(vinylidene fluoride)(PVDF)shows excellent electro-activity and is promising for flexible electronic devices.However,the processing of PVDF into the favourable ferroelectric structure(β-phase)presents difficulties,while its copolymer with trifluoroethylene(PVDF-TrFE)can directly crystallize into β-phase,but shows limited thermal stability and high-cost processing.As a result,an easily implementable method,pressing-and-folding(P&F),was used to produce highly compatible blended films of PVDF and PVDF-TrFE without using any hazardous solvent or complex polymer processing equipment.Hot-pressed PVDF(molecular weight:530 kg/mol)and PVDF-TrFE(molar ratio:51/49)films were firstly stacked before undergoing P&F treatment.Compared to extrusion-blended films before and after P&F,the P&F stacked films showed isotropic crystalline structure of b-phase,as confirmed using X-ray diffraction and infrared spectroscopy.The ferroelectric remnant polarization of the P&F stacked films is 0.068 C/m^(2),surpassing pure PVDF-TrFE(0.062 C/m^(2))and the simulated value of remnant polarization of pure PVDF(~0.065 C/m^(2)).The above findings promise to provide inspirations for new processing strategy on PVDF-based functional polymers.