Boosting rate performance of layered lithium-rich cathode materials by oxygen vacancy induced surface multicomponent integration

The rapid development of electric vehicles and portable energy storage systems demands improvements in the energy density and cost-effectiveness of lithium-ion batteries,a domain in which Lithium-rich layered cathode(LLO)materials inherently excel.However,these materials face practical challenges,such as low initial Coulombic efficiency,inferior cycle/rate performance,and voltage decline during cycling,which limit practical application.Our study introduces a surface multi-component integration strategy that incorporates oxygen vacancies into the pristine LLO material Li1.2Mn_(0.6)Ni_(0.2)O_(2).This process involves a brief citric acid treatment followed by calcination,aiming to explore rate-dependent degradation behavior.The induced surface oxygen vacancies can reduce surface oxygen partial pressure and diminish the generation of O_(2)and other highly reactive oxygen species on the surface,thereby facilitating the activation of Li ions trapped in tetrahedral sites while overcoming transport barriers.Additionally,the formation of a spinel-like phase with 3D Li+diffusion channels significantly improves Li^(+)diffusion kinetics and stabilizes the surface structure.The optimally modified sample boasts a discharge capacity of 299.5 mA h g^(-1)at a 0.1 C and 251.6 mA h g^(-1)at a 1 C during the initial activation cycle,with an impressive capacity of 222.1 mA h g^(-1)at a 5 C.Most notably,it retained nearly 70%of its capacity after 300 cycles at this elevated rate.This straightforward,effective,and highly viable modification strategy provides a crucial resolution for overcoming challenges associated with LLO materials,making them more suitable for practical application.

Offline two-dimensional liquid chromatography coupled with ion mobility-quadrupole time-of-flight mass spectrometry enabling fourdimensional separation and characterization of the multicomponents from white ginseng and red ginseng

Inherent complexity of plant metabolites necessitates the use of multi-dimensional information to accomplish comprehensive profiling and confirmative identification.A dimension-enhanced strategy,by offline two-dimensional liquid chromatography/ion mobility-quadrupole time-of-flight mass spectrometry(2 D-LC/IM-QTOF-MS)enabling four-dimensional separations(2 D-LC,IM,and MS),is proposed.In combination with in-house database-driven automated peak annotation,this strategy was utilized to characterize ginsenosides simultaneously from white ginseng(WG)and red ginseng(RG).An offline 2 DLC system configuring an Xbridge Amide column and an HSS T3 column showed orthogonality 0.76 in the resolution of ginsenosides.Ginsenoside analysis was performed by data-independent high-definition MSE(HDMSE)in the negative ESI mode on a Vion?IMS-QTOF hybrid high-resolution mass spectrometer,which could better resolve ginsenosides than MSEand directly give the CCS information.An in-house ginsenoside database recording 504 known ginsenosides and 58 reference compounds,was established to assist the identification of ginsenosides.Streamlined workflows,by applying UNIFI?to automatedly annotate the HDMSEdata,were proposed.We could separate and characterize 323 ginsenosides(including 286 from WG and 306 from RG),and 125 thereof may have not been isolated from the Panax genus.The established 2 D-LC/IM-QTOF-HDMSEapproach could also act as a magnifier to probe differentiated components between WG and RG.Compared with conventional approaches,this dimensionenhanced strategy could better resolve coeluting herbal components and more efficiently,more reliably identify the multicomponents,which,we believe,offers more possibilities for the systematic exposure and confirmative identification of plant metabolites.

Progress and prediction of multicomponent quantification in complex systems with practical LC-UV methods

Complex systems exist widely,including medicines from natural products,functional foods,and biological samples.The biological activity of complex systems is often the result of the synergistic effect of multiple components.In the quality evaluation of complex samples,multicomponent quantitative analysis(MCQA)is usually needed.To overcome the difficulty in obtaining standard products,scholars have proposed achieving MCQA through the“single standard to determine multiple components(SSDMC)”approach.This method has been used in the determination of multicomponent content in natural source drugs and the analysis of impurities in chemical drugs and has been included in the Chinese Pharmacopoeia.Depending on a convenient(ultra)high-performance liquid chromatography method,how can the repeatability and robustness of the MCQA method be improved?How can the chromatography conditions be optimized to improve the number of quantitative components?How can computer software technology be introduced to improve the efficiency of multicomponent analysis(MCA)?These are the key problems that remain to be solved in practical MCQA.First,this review article summarizes the calculation methods of relative correction factors in the SSDMC approach in the past five years,as well as the method robustness and accuracy evaluation.Second,it also summarizes methods to improve peak capacity and quantitative accuracy in MCA,including column selection and twodimensional chromatographic analysis technology.Finally,computer software technologies for predicting chromatographic conditions and analytical parameters are introduced,which provides an idea for intelligent method development in MCA.This paper aims to provide methodological ideas for the improvement of complex system analysis,especially MCQA.

Bismuth (III) Triflate Catalyzed Multicomponent Synthesis of 2,4,5-Trisubstituted Imidazoles

Substituted imidazoles are of interest because of their useful biological activities. While several methods have been developed for the synthesis of such compounds, some of the reported methods utilize corrosive or toxic catalysts. We report a bismuth (III) triflate catalyzed multicomponent synthesis of 2,4,5-trisubstituted imidazoles. Bismuth (III) compounds are attractive from a green chemistry perspective because they are remarkably non-toxic and non-corrosive. Multicomponent syntheses save time and generate less waste.

The(1+1)-dimensional nonlinear ion acoustic waves in multicomponent plasma containing kappa electrons

Large amplitude (1+1)-dimensional nonlinear ion acoustic waves are theoretically studied in multicomponent plasma consisting of positively charged ions and negatively charged ions, ion beam, kappa-distributed electrons, and dust grains,respectively. By using the Sagdeev potential method, the dynamical system and the Sagdeev potential function are obtained.The important influences of system parameters on the phase diagram of this system are investigated. It is found that the linear waves, the nonlinear waves and the solitary waves are coexistent in the multicomponent plasma system. Meanwhile,the variations of Sagdeev potential with parameter can also be obtained. Finally, it seems that the propagating characteristics of (1+1)-dimensional nonlinear ion acoustic solitary waves and ion acoustic nonlinear shock wave can be influenced by different parameters of this system.

Bismuth (III) Triflate Catalyzed Multicomponent Synthesis of 2,4,5-Trisubstituted Imidazoles

Substituted imidazoles are of interest because of their useful biological activities. While several methods have been developed for the synthesis of such compounds, some of the reported methods utilize corrosive or toxic catalysts. We report a bismuth (III) triflate catalyzed multicomponent synthesis of 2,4,5-trisubstituted imidazoles. Bismuth (III) compounds are attractive from a green chemistry perspective because they are remarkably non-toxic and non-corrosive. Multicomponent syntheses save time and generate less waste.

经典名方羌活胜湿汤中12种成分的LC-MS/MS定量分析

[目的]建立液相色谱-质谱联用(LC-MS/MS)分析方法用于测定羌活胜湿汤颗粒中5-O-甲基维斯阿米醇苷、紫花前胡苷、蔓荆子黄素、羌活醇、蛇床子素、二氢欧山芹醇当归酸酯、异甘草苷、甘草苷、绿原酸、异甘草素、甘草素、阿魏酸12种成分的含量。[方法]色谱柱为ACQUITY UPLC BEH C18柱(2.1 mm×100 mm,1.7μm),流动相为0.1%的甲酸水溶液和乙腈,梯度洗脱,流速为0.3 mL/min,柱温为30℃,进样量为5μL。采用电喷雾离子源(ESI)、多反应监测模式(MRM)进行正负离子同时扫描。[结果]羌活胜湿汤颗粒中12种成分在线性范围内线性关系良好,精密度、重复性、稳定性及加样回收率试验均满足要求。[结论]实验建立的含量测定方法高效、稳定、可靠,可用于羌活胜湿汤颗粒的质量控制研究。

多组分多层级3D打印材料研究进展

多组分多层级3D打印材料(McMl3DPMs)是一种新兴的先进材料,源于多孔材料、复合材料和增材制造的融合。由于增材制造赋予了Mc Ml3DPMs三维架构跨越广泛组分构成和结构类型的能力,Mc Ml3DPMs拥有杰出的机械性能,甚至是通常被认为相互排斥的性能(例如高强度和高韧性)。本文重点介绍为了实现高性能结构用Mc Ml3DPMs所必须解决的科学挑战以及最近研究工作对此做出的努力,将从结构设计、制造过程建模、缺陷表征和性能评价3个方面对相关案例进行回顾。最后,本文指出了当前研究的不足之处,并展望了Mc Ml3DPMs的未来发展,包括讨论了进一步推进这一新兴领域发展的几个可能的研究方向。

超临界多元流体模拟实验研究

随着油气勘探开发的不断发展,井深逐步加大,压力、温度也逐步升高,伴随着蒸汽吞吐、蒸汽驱特别是火烧油层等技术的应用,开采层的温度、压力可能达到水的超临界点。由于超临界水有很多性质,如具有极强的氧化能力,可以溶解很多物质(比如油),能够缓慢地溶解腐蚀几乎所有金属,具有超级催化作用,这些性质对油藏的开发有着极大的影响。超临界多元流体模拟实验系统可以在室内条件下,通过模拟实际深井条件,进行超临界多元流体对原油采收的影响的探索;进行超临界多元流体对油、套管及地层的腐蚀影响的研究。

柴油机缸内超临界环境甲醇/正庚烷液滴蒸发过程

采用分子动力学模拟方法研究了甲醇/正庚烷混合燃料液滴在不同温度(400、700、1000 K)、不同压力(2、5、7 MPa)下不同甲醇掺混质量分数(0、10%、20%、30%)的蒸发过程。结果表明:正庚烷液滴的蒸发直径随时间的变化相对平滑,甲醇/正庚烷混合燃料液滴中甲醇的蒸发对超临界环境条件更加敏感,混合燃料液滴蒸发过程波动更加剧烈。基于蒸发速率、液滴分子数和界面厚度3个指标,提出了液滴蒸发阶段的3种划分方法,并讨论了3种划分方法在不同环境条件及燃料成分下的适用范围;提出界面厚度变化率作为判断临界状态转变的指标,当界面厚度变化率大于0.04 nm/ps时,认为液滴发生亚临界向超临界的转变;基于界面厚度变化率突变时刻,建立了甲醇/正庚烷液滴临界相变预测模型,计算结果表明,甲醇掺混质量分数达到或超过44%时观察不到界面厚度变化率突变的现象,即液滴亚临界向超临界转变的时间可以忽略。

一种多分量信号分解方法:时频滤波分解

为解决目前信号分解分量时频域紧邻、重叠和间歇性复杂时频特征的多分量非平稳、非线性信号时,分解困难和效率低的问题,本文提出了一种基于信号时频分布的多分量非平稳信号分解方法——时频滤波分解(Time-Frequency Filtering Decomposition,TFFD). TFFD通过拟合所选反映信号中各分量时频瞬时特征与规律的时频域基准数据点,得到与分量实际瞬时频率(Instantaneous Frequency,IF)一致的拟合IF曲线,并以拟合IF曲线的时频坐标为基础,设置距离阈值条件确定分量在时频图上的分布区域,构造以拟合IF曲线时频坐标为中心频率、分布区域频宽为通带宽度的时频滤波器组,实现对多分量信号的时频滤波分解.通过对具有代表性时频特征的仿真和实际信号分析,并与经典信号分解方法对比,证明了TFFD方法优良的分解能力和分解效率.

负温度系数区域内RP-3喷气燃料表征燃料化学反应动力学分析

为探究喷气燃料(RP-3)在不同条件下负温度系数(NTC)区域内的反应路径、敏感反应以及小分子基元团的影响规律,以CRECK小分子详细机理为核心,基于解耦法耦合正十二烷、正丁基环己烷、正丁基苯简化机理,构建得到RP-3多组分表征燃料化学反应动力学详细机理;并在不同压力、燃料/空气质量比工况下对其NTC区域内的燃烧过程进行了敏感性分析、组分含量变化分析以及组分间交互作用路径分析。结果表明:NTC区域内反应H_(2)O_(2)(+M)=2OH(+M)(M为反应中第三体)是最重要的着火促进反应;不同反应条件下O_(2)、CH_(4)、C_(2)H_(4)的陡降时刻与CO_(2)的激增时刻均与燃料的着火延迟期表现出极高的吻合度;压力与燃料/空气质量比的改变仅会影响反应路径的占比。

多分量LFM干扰及动态环境下DBOC信号的捕获

针对双二进制偏移载波(double binary offset carrier,DBOC)信号在多分量线性调频(linear frequency modulation,LFM)干扰和动态环境下捕获算法缺乏的问题,提出布莱克曼窗预处理结合分数阶傅里叶变换(fractionalFouriertransform,FRFT)的干扰抑制算法以及离散多项式相位变换(discretepolynomial-phase transform,DPT)、部分匹配滤波器(partial matching filter,PMF)结合快速傅里叶变换(fast Fourier transform,FFT)加频谱校正的捕获算法。该算法首先对接收信号做布莱克曼窗预处理,抑制干扰谱线输出旁瓣,提高干扰汇聚的精确性;然后利用分级算法快速搜索信号的最优阶数,在保证精度量级的条件下减少了运算量;最后,在对应的最优阶数下做FRFT,结合干扰判断和轮询算法,逐个完成多分量LFM干扰的抑制。对干扰抑制后的信号首先利用定阶算法确定其动态阶数;然后通过DPT对动态信号做降阶处理,去除动态项;最后利用PMF-FFT加频谱校正完成DBOC信号的捕获。仿真结果表明,所提算法能够准确并完全地对三个LFM干扰分量进行逐个抑制,且抑制后的干扰分量不会对其他干扰分量的抑制造成影响。在检测概率达到1时,经过布莱克曼窗预处理后算法的信噪比比经过汉明窗预处理和经过凯塞窗预处理后算法的信噪比分别提升了4 dB和6.4 dB,比未经过预处理算法的信噪比提升了7.2 dB。此外,使用频谱校正可以突出捕获峰值,提高捕获精度。与未经频谱校正算法相比,经过频谱校正后算法的信噪比提升了1.6 dB,且能减少一定的捕获时间。

老年肌少症的运动干预

背景:肌少症是指与增龄相关的进行性、全身肌量减少和/或肌强度下降或肌肉生理功能减退,该病症与老年人多种不良结局的发生有关。运动被认为是老年人对抗肌少症的主要策略之一,但当前缺乏对不同运动方式干预肌少症的具体干预方式研究。目的:阐述肌少症的主要影响因素和不同运动方式改善老年肌少症的研究进展,为老年人对抗肌少症提供参考和依据。方法:英文检索词为“sarcopenia,sport,exercise intervention,resistant training,aerobic exercise,whole body vibration training,mixed training,physical performance,muscle strength,muscle mass等”;中文检索词为“肌少症、运动、运动干预、抗阻运动、有氧运动、全身振动训练、多组分运动、身体表现、肌肉力量、肌肉质量等”,分别检索Web of Science、PubMed、中国知网、维普、万方数据库,检索时限为2000年1月至2023年10月,对入选的126篇文献进行归纳总结。结果与结论:(1)抗阻运动仍是防治老年肌少症的最有效运动方式,且高强度抗阻运动效果更为显著,但在实际应用中应注意训练负荷强度的循序渐进;(2)有氧运动结合抗阻运动对老年人肌肉质量和功能的改善相对于单一运动模式效果更好,建议老年人前期可以进行低强度有氧运动过渡,后期可以个体化增加抗阻运动;(3)全身振动训练是一种新兴的防治老年肌少症的治疗方法,但在实际应用过程中要尤其注意频率、振幅、持续时间对患者的影响;(4)多组分运动结合了不同运动方式,可以最大程度发挥各自的优势,从而对其进行个性化运动干预。

基于时空多成分模型的中缅边境地区景洪市登革热流行特征分析

目的了解中缅边境地区景洪市2019年登革热时空分布特征及传播影响因素。方法收集中缅边境地区景洪市2019年登革热本地病例逐日发病数,将人口密度、人均GDP、日平均气温、日平均相对湿度和日照时数等因素作为协变量,构建基于Power-law算法的时空多成分模型,通过赤池信息量(Akaike information criterion,AIC)来评价模型的拟合效果。结果中缅边境地区景洪市2019年累计报告3303例登革热本地病例,发病率为763.44/10万。将人均GDP纳入时间自相关成分,同时将人口密度、日平均气温、日平均最高气温和日平均相对湿度纳入局部特性成分的时空多成分模型的拟合效果最优(AIC=2317),此时时间自相关成分为0.2151[95%CI:(0.0812,0.5702)]、空间流行成分为0.0004[95%CI:(0.0002,0.0010)]、局部特性成分为3.0152[95%CI:(1.6507,5.5078)]。协变量日平均相对湿度、人口密度、人均GDP、日平均气温、日平均最高气温的作用强度依次为2.8159[95%CI:(0.0216,367.1685)]、1.8227[95%CI:(1.4976,2.2183)]、1.2088[95%CI:(1.0577,1.3816)]、0.3561[95%CI:(0.0119,10.6739)]、0.3104[95%CI:(0.0036,126.5482)]。对发病数>20例的区域分析发现,允景洪街道、西双版纳旅游度假区和景洪工业园区时间自相关成分影响较大,嘎洒镇、勐龙镇和勐罕镇局部特性成分影响较大。结论景洪市不同区域登革热时空构成存在差异性,具有不同的时空传播特征。人均GDP会扩大前期疫情对后期疫情传播的影响,人口密度、日平均气温、日平均最高气温和日平均相对湿度则会影响研究区域登革热本地风险水平。

Phase field simulation for non-isothermal solidification of multicomponent alloys coupled with thermodynamics database

In order to quantitively model the real solidification process of industrial multicomponent alloys, a non-isothermal phase field model was studied for multicomponent alloy fully coupled with thermodynamic and diffusion mobility database, which can accurately predict the phase equilibrium, solute diffusion coefficients, specific heat capacity and latent heat release in the whole system. The results show that these parameters are not constants and their values depend on local concentration and temperature. Quantitative simulation of solidification in multicomponent alloys is almost impossible without such parameters available. In this model, the interfacial region is assumed to be a mixture of solid and liquid with the same chemical potentials, but with different composition. The anti-trapping current is also considered in the model. And this model was successfully applied to industrial A1-Cu-Mg alloy for the free equiaxed dendrite solidification process.

氮化硅陶瓷低温烧结助剂研究进展

氮化硅陶瓷性能优异,然而由于其共价键较强,自扩散系数小,烧结难度较大。目前高性能氮化硅陶瓷主要通过高温气压烧结法制备,烧结温度在1800℃以上,对设备要求较高,制备成本也较高,限制了氮化硅陶瓷的实际应用。低温烧结作为降低氮化硅生产成本的有效途径之一,受到了业界广泛关注。目前国内外关于氮化硅陶瓷低温烧结的研究主要集中在烧结助剂的选择方面,烧结助剂可以分为两类:使用与SiO_(2)共晶温度较低的烧结助剂和使用多组分烧结助剂。综述了这两类低温烧结助剂的研究进展,并提出了低温烧结助剂选择的合理方案。综合来看,要在低温下制得性能良好的氮化硅陶瓷,需选用与SiO_(2)具有低共晶点的烧结助剂,并配合使用多元组分调控氮化硅陶瓷的微观结构和性能。

Numerical analysis of multicomponent responses of surface-hole transient electromagnetic method

We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.

多成分运动在老年人健康促进中的应用进展

对多成分运动的概念、形式、促进老年人健康的应用现状,以及其与营养补充、认知训练、日常生活活动训练的联合干预现状进行综述,以期为老年人应用多成分运动健康干预提供依据。

Attenuation compensation in multicomponent Gaussian beam prestack depth migration

Gaussian beam prestack depth migration is an accurate imaging method of subsurface media. Prestack depth migration of multicomponent seismic data improves the accuracy of imaging subsurface complex geological structures. Viscoelastic prestack depth migration is of practical significance because it considers the viscosity of the subsurface media. We use Gaussian beam migration to compensate for the attenuation in multicomponent seismic data. First, we use the Gaussian beam method to simulate the wave propagation in a viscoelastic medium and introduce the complex velocity Q-related and exact viscoelastic Zoeppritz equation. Second, we discuss PP- and PS-wave Gaussian beam prestack depth migration algorithms for common-shot gathers to derive expressions for the attenuation and compensation. The algorithms correct the amplitude attenuation and phase distortion caused by Q, and realize multicomponent Gaussian beam prestack depth migration based on the attenuation compensation and account for the effect of inaccurate Q on migration. Numerical modeling suggests that the imaging resolution of viscoelastic Gaussian beam prestack depth migration is high when the viscosity of the subsurface is considered.