Synthesis of spherical nano-ZSM-5 zeolite with intergranular mesoporous for alkylation of ethylbenzene with ethanol to produce m-diethylbenzene

Catalytic synthesis of m-diethylbenzene(m-DEB)through alkylation of ethylbenzene(EB)may be a promising alternative route in comparison with traditional rectification of mixed DEB,for which the top priority is to develop efficient and stable heterogeneous catalysts.Here,the spherical nano-ZSM-5 zeolite with abundant intergranular mesoporous is synthesized by the seed-mediated growth method for alkylation of EB with ethanol to produce m-DEB.The results show that the spherical nano-ZSM-5 zeolite exhibits better stability and higher alkylation activity at a lower temperature than those of commercial micropore ZSM-5.And then,the spherical nano-ZSM-5 is further modified by La_(2)O_(3) through acid treatment followed by immersion method.The acid treatment causes nano-ZSM-5 to exhibit the increased pore size but decreased the acid sites,and subsequent La_(2)O_(3) loading reintroduces the weak acid sites.As a result,the HNO_(3)-La_(2)O_(3)-modified catalyst exhibits a slight increase in EB conversion and DEB yield in comparison with unmodified one,and meanwhile,it still maintains high m-DEB selectivity.The catalyst after acid treatment achieves higher catalytic stability besides maintaining the high alkylation activity of EB with ethanol.The present study on the spherical nano-HZSM-5 zeolite and its modification catalyst with excellent alkylation ability provides new insights into the production of mDEB.

Association Between Lipid Profiles and Left Ventricular Hypertrophy:New Evidence from a Retrospective Study

Objective To explore the association between lipid profiles and left ventricular hypertrophy in a Chinese general population.Methods We conducted a retrospective observational study to investigate the relationship between lipid markers[including triglycerides,total cholesterol,low-density lipoprotein cholesterol,high-density lipoprotein(HDL)cholesterol,non-HDL-cholesterol,apolipoprotein A-I,apolipoprotein B,lipoprotein[a],and composite lipid profiles]and left ventricular hypertrophy.A total of 309,400 participants of two populations(one from Beijing and another from nationwide)who underwent physical examinations at different health management centers between 2009 and 2018 in China were included in the cross-sectional study.7,475 participants who had multiple physical examinations and initially did not have left ventricular hypertrophy constituted a longitudinal cohort to analyze the association between lipid markers and the new-onset of left ventricular hypertrophy.Left ventricular hypertrophy was measured by echocardiography and defined as an end-diastolic thickness of the mterventricular septum or left ventricle posterior wall>11 mm.The Logistic regression model was used in the cross-sectional study.Cox model and Cox model with restricted cubic splines were used in the longitudinal cohort.Results In the cross-sectional study for participants in the highest tertile of each lipid marker compared to the respective lowest,triglycerides[odds ratio(OR):1.2S0,95%CI:1.060 to 1.474],HDL-cholesterol(OR:0.780,95%CI:0.662 to 0.918),and lipoprotein(a)(OR:1.311,95%C7:1.115 to 1.541)had an association with left ventricular hypertrophy.In the longitudinal cohort,for participants in the highest tertile of each lipid marker at the baseline compared to the respective lowest,triglycerides[hazard ratio(HR):3.277,95%C/:1.720 to 6.244],HDL-cholesterol(HR:0.516,95%C7:0.283 to 0.940),non-HDL-cholesterol(HR:2.309,95%C/:1.296 to 4.112),apolipoprotein B(HR:2.244,95%CI:1.251 to 4.032)showed an association with new-onset left ventricular hypertrophy.In the Cox model with forward stepwise selection,triglycerides were the only lipid markers entered into the final model.Conclusion Lipids levels,especially triglycerides,are associated with left ventricular hypertrophy.Controlling triglycerides level potentiate to be a strategy in harnessing cardiac remodeling but deserve to be furdier investigated.

基于IP网络的信息系统融合设计

客滚船上的信息系统包含有视频监控系统,电视系统,电话系统,局域网系统等,传统上是各自独立配,此种情况下,各系统的线路和终端布设复杂,日常管理不便。将上述系统进行基于IP网络的融合设计,可简化系统的设计,有效降低系统整体复杂度和建造成本。本文对客滚船基于IP网络的信息系统的架构、接入系统进行介绍,并阐述了这样设计的利弊及注意事项,对开展船舶信息系统融合设计有一定的指导意义。

Enhanced Thermoelectric Properties of Cu_(x)Se(1.75 ≤ x ≤ 2.10) during Phase Transitions

Coupling of a phase transition to electron and phonon transports provides extra degree of freedom to improve the thermoelectric performance, while the pertinent experimental and theoretical studies are still rare. Particularly,the impaction of chemical compositions and phase transition characters on the abnormal thermoelectric properties across phase transitions are largely unclear. Herein, by varying the Cu content x from 1.75 to 2.10, we systemically investigate the crystal structural evolution, phase transition features, and especially the thermoelectric properties during the phase transition for Cu_(x)Se. It is found that the addition of over-stoichiometry Cu in Cu_(x)Se could alter the phase transition characters and suppress the formation of Cu vacancies. The critical scatterings of phonons and electrons during phase transitions strongly enhance the Seebeck coefficient and diminish the thermal conductivity, leading to an ultrahigh dimensionless thermoelectric figure of merit of ~1.38 at 397 K in Cu_(2.10)Se.With the decreasing Cu content, the critical electron and phonon scattering behaviors are mitigated, and the corresponding thermoelectric performances are reduced. This work offers inspirations for understanding and tuning the thermoelectric transport properties during phase transitions.

Doping-induced charge transfer in conductive polymers

Molecular doping has become a widely used method to modulate the electric performance of organic semiconductors(OSC).Highly effective charge transfer during molecular doping is desired to achieve ideal electrical conductivity.Two types of charge transfer mechanisms are widely accepted in molecular doping process:integer charge transfer(ICT)and charge transfer complex(CTC).In this review,fundamental principles of two mechanisms are revisited and the characterization methods are depicted.The key points for the formation of two mechanisms are highlighted from aspects of molecular structure and process engineering.Then,the strategies to improve the proportion of ICT are discussed.Finally,the challenges and perspectives for future developments in the molecular doping of polymer semiconductors are provided.

Breakthrough in room-temperature plastic ceramic

The pursuit of structural materials that embody both high strength and significant plastic deformability is pivotal to ensuring safety and reliability across diverse applications.However,achieving this dual characteristic within a single material has long posed a formidable challenge in the realm of materials science.Metals,renowned for their excellent plasticity facilitated by the delocalization of valence electrons.

立足基础 面向应用 构筑热电科学与技术创新链——“热电材料与器件”重点项目群结题综述

国家自然科学基金重点项目群“热电材料和器件的基础研究”历时5年(2017年1月至2021年12月)完成。该重点项目群针对热电材料电、热输运协同调控关键科学问题,开展热电材料的微观结构设计、可控制备、器件设计集成等研究,在多元强弱化学键及亚晶格结构热电材料、电热输运理论、多场耦合可控制备、级联器件设计集成等方面取得了一系列创新成果。本文主要综述该重点项目群的统筹和立项背景、科学问题、组织实施过程、重要创新成果、总体完成情况等,并展望了热电材料科学与应用技术的未来发展趋势。

High-temperature oxidation mechanism of ZrCoSb-based half-Heusler thermoelectric compounds

ZrCoSb-based half-Heusler(HH)compounds are among the most promising thermoelectric(TE)materials for high-temperature power generation.Oxidation resistance is one of the key issues for realizing the practical application of TE materials for long-term service in the ambient working environment.In this work,the oxidation behavior of Zr_(0.5)Hf_(0.5)CoSb_(0.8)Sn_(0.2)(ZHCSS)half-Heusler is systematically studied in the service temperature range from 873 to 1073 K.It is revealed that three typical layers of oxidation products tend to form on the surface of HH sample,namely,the dense oxide layer(DOL)composed of(Zr,Hf)O_(2) and CoSb,the alternate oxide layer(AOL)composed of repeated(Zr,Hf)O_(2) and CoSb_(2)O_(6)/Co_(3)O_(4),and the CoSb layer between the DOL and AOL.The mass gain during oxidation is mainly caused by the rapid growth of AOL,which is controlled by the outward diffusion of Zr/Hf and the inward diffusion of oxygen.The formation of a continuous CoSb layer and DOL is found beneficial to block the outward diffusion of Zr/Hf.Based on the analysis of the dominant factors on the outward and inward diffusions as well as the reaction activation energy,a simple approach is proposed to improve the oxidation resistance of Zr_(0.5)Hf_(0.5)CoSb_(0.8)Sn_(0.2)by pre-oxidizing the sample in low oxygen pressure to form the dense(Zr,Hf)O_(2) and CoSb layers as oxidation protecting and/or diffusion blocking layers.The oxidation test shows the effectiveness of such pre-oxidation on the formation and growth of the AOL and therefore on improving the service stability of Zr_(0.5)Hf_(0.5)CoSb_(0.8)Sn_(0.2)at high temperatures in the air.

高性能柔性碲化铋/碳纳米管复合热电薄膜

热电材料是可将热能与电能相互直接转换的绿色能源材料[1,2],其能量转换效率主要取决于材料与器件性能,不依赖于能量体系的大小,因而在微小热源的回收发电、局部“热点”的快速精确制冷等技术领域具有显著的优势,在环境温差原位发电、低品位分散式热源利用、电子器件/微系统芯片温控等领域具有重要的应用.在实际应用中,许多“热源”具有复杂的几何结构和曲率任意变化的表面(如热源管道、微系统硬件等),或者“热源”自身具有可变形性等特点(如人体体温热源等[3]).

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

During the last two decades,we have witnessed great progress in research on thermoelectrics.There are two primary focuses.One is the fundamental understanding of electrical and thermal transport,enabled by the interplay of theory and experiment;the other is the substantial enhancement of the performance of various thermoelectric materials,through synergistic optimisation of those intercorrelated transport parameters.Here we review some of the successful strategies for tuning electrical and thermal transport.For electrical transport,we start from the classical but still very active strategy of tuning band degeneracy(or band convergence),then discuss the engineering of carrier scattering,and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials.For thermal transport,we summarise the approaches for studying thermal transport based on phonon–phonon interactions valid for conventional solids,as well as some quantitative efforts for nanostructures.We also discuss the thermal transport in complex materials with chemical-bond hierarchy,in which a portion of the atoms(or subunits)are weakly bonded to the rest of the structure,leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures.In this review,we provide a summary of achievements made in recent studies of thermoelectric transport properties,and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment,and point out some challenges and possible directions.

铜基硫族化合物热电材料（英文）

铜基硫族化合物因其高性能、可调的输运性质、高丰度和低毒性,被认为是很有前景的新型热电材料,引起了研究者的广泛关注.本文总结了近年来铜基热电材料的研究进展,包括类金刚石结构材料、声子液体二元及多元化合物等.本文首先总体介绍了两套亚晶格的基本特征及其对热学、电学性质的影响:一方面,复杂晶体结构和无序、甚至液态化的亚晶格导致极低的热导率;另一方面,刚性亚晶格构成电荷传输通道,保证了较高的电学性能.然后,本文针对特定的几类材料体系,详细介绍了其典型结构特征与"结构-性能"构效关系,以及掺杂、固溶、能带结构调控和纳米结构设计等多尺度优化手段.最后,本文从材料研发和器件研制的角度评述了铜基硫族化合物作为热电材料的应用前景及相关进展.

Fabrication,Microstructure and Mechanical Properties of TiC/Ti_2AlC/TiAl_3 in situ Composite

This paper described a process for synthesizing a new multiphase TiC/Ti2AlC/TiAl3 composite, in which Ti, A14C3 and graphite powders were utilized as raw materials, and in situ spark plasma sintering-reactive sintering （SPS-RS） methods were involved. The intermediate phases of Ti3Al and TiAl were found during the reactive sintering process and the reactions for the phase＇s formation were proposed. The microstructure and mechanical properties of the composites were investigated. The high-resolution transmission electron microscopy （HRTEM） image of the interface showed that no amorphous phases were detected along the grain boundary. The orientation relationships between the Ti2AIC and the TiC were shown to be （0001）Ti2AlC｜｜（111）TiC and [1210]Ti2AlC｜｜[110]Tic. The average hardness, fracture toughness, Young＇s modulus and bending strength of the composite were 15.1±0.8 GPa, 4.9±0.3 MPa.mU2, 261±13 GPa and 776±18 MPa, respectively. The toughening mechanism was also discussed.

Room-temperature plastic inorganic semiconductors for flexible and deformable electronics

Flexible electronics ushers in a revolution to the electronics industry in the 21st century.Ideally,all components of a flexible electronic device including the functional component shall comply with the deformation to ensure the structural and functional integrity,imposing a pressing need for developing roomtemperature strain-tolerant semiconductors.To this end,there is a long-standing material dilemma:inorganic semiconductors are typically brittle at room temperature except for size-induced flexibility;by contrast,organic semiconductors are intrinsically soft and flexible but the electrical performance is poor.This is why the discovery of bulk plasticity in Ag2S at room temperature and ZnS in darkness is groundbreaking in solving this long-standing material dilemma between the mechanical deformability and the electrical performance.The present review summarizes the background knowledge and latest advances in the emerging field of plastic inorganic semiconductors.At the outset,we argue that the plasticity of inorganic semiconductors is vital to strain tolerance of electronic devices,which has not been adequately emphasized.The mechanisms of plasticity are illustrated from the perspective of chemical bonding and dislocations.Plastic inorganic materials,for example,ionic crystals(insulators),ZnS in darkness,and Ag2S,are discussed in detail in terms of their prominent mechanical properties and potential applications.We conclude the article with several key scientific and technological questions to address in the future study.

Crystalline Structure-Dependent Mechanical and Thermoelectric Performance in Ag_(2)Se_(1‐x)S_(x)System

Self-powered wearable electronics require thermoelectric materials simultaneously with a high dimensionless figure of merit(zT)and good flexibility to convert the heat discharged by the human body into electricity.Ag_(2)(S,Se)-based semiconducting materials can well satisfy these requirements,and thus,they are attracting great attention in thermoelectric society recently.Ag_(2)(S,Se)crystalizes in an orthorhombic structure or monoclinic structure,depending on the detailed S/Se atomic ratio,but the relationship between its crystalline structure and mechanical/thermoelectric performance is still unclear to date.In this study,a series of Ag_(2)Se_(1-x)S_(x)(x=0,0.1,0.2,0.3,0.4,and 0.45)samples were prepared and their mechanical and thermoelectric performance dependence on the crystalline structure was systematically investigated.x=0:3 in the Ag_(2)Se_(1-x)S_(x)system was found to be the transition boundary between orthorhombic and monoclinic structures.Mechanical property measurement shows that the orthorhombic Ag_(2)Se_(1-x)S_(x)samples are brittle while the monoclinic Ag_(2)Se_(1-x)S_(x)samples are ductile and flexible.In addition,the orthorhombic Ag_(2)Se_(1-x)S_(x)samples show better electrical transport performance and higher zT than the monoclinic samples under a comparable carrier concentration,most likely due to their weaker electron-phonon interactions.This study sheds light on the further development of flexible inorganic TE materials.

Phase-modulated mechanical and thermoelectric properties of Ag_(2)S_(1-x)Te_(x)ductile semiconductors

By virtue of the excellent plasticity and tunable transport properties,Ag_(2)S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications.Among them,Ag_(2)S_(1-x)Te_(x)exhibits rich and interesting variations in crystal structure,mechanical and thermoelectric transport properties.However,Te alloying obviously introduces extremely large order-disorder distributions of cations and anions,leading to quite complicated crystal structures and thermoelectric properties.Detailed composition-structure-performance correlation of Ag_(2)S_(1-x)Te_(x)still remains to be established.In this work,we designed and prepared a series of Ag_(2)S_(1-x)Te_(x)(x=0-0.3)materials with low Te content.We discovered that the monoclinic-to-cubic phase transition occurs around x=0.16 at room temperature.Te alloying plays a similar role as heating in facilitating this monoclinic-to-cubic phase transition,which is analyzed based on the thermodynamic principles.Compared with the monoclinic counterparts,the cubic-structured phases are more ductile and softer in mechanical properties.In addition,the cubic phases show a degenerately semiconducting behavior with higher thermoelectric performance.A maximum zT=0.8 at 600 K and bending strain larger than 20% at room temperature were obtained in Ag_(2)S_(0.7)Te_(0.3).This work provides a useful guidance for designing Ag_(2)S-based alloys with enhanced plasticity and high thermoelectric performance.

Ultrahigh figure-of-merit of Cu2Se incorporated with carbon coated boron nanoparticles

Cu2Se based thermoelectric materials are of great potential for high-temperature energy harvesting due to their high-temperature figure-of-merit(zT).For further development of Cu2Se,both engineering and mid-temperature figure-of-merit need to be improved.In this work,we report that carbon-coated boron(C/B)nanoparticles incorporation can significantly improve both mid-and high-temperature zT in Cu2Se.The nanoparticle inclusions can result in a homogeneous distribution of Cu:C:B interfaces responsible for both improvement of the Seebeck coefficient and significantly reduction in thermal conductivity.Ultrahigh mid-and high temperature thermoelectric performance with zT=1.7 at 700 K and 2.23 at 1000 K as well as significantly improved engineering zT are achieved in the C/B incorporated Cu2Se with desirable mechanical properties and cycling stability.Our findings will stimulate further study and exploration for the Cu2Se based thermoelectric materials for broad applications in converting waste heat to electricity with competitive energy conversion efficiency.

Cu2Se相变过程中热电效率增强的电子起源

热电材料可实现热能向电能的转换,是解决能源危机的潜在方式.目前热电材料的发展受限于较低的热电转换效率(可由热电优值zT评估),探索新型高zT热电材料或提升现有热电材料的z T值是亟待解决的重要课题.Cu2Se作为一种传统的超离子高z T热电材料一直备受关注.研究表明在其400 K附近的相变过程中,z T迅速提升了3倍.目前对这一变化的研究多限于晶体结构方面,而电子性质研究仅限于理论计算.本文利用高分辨角分辨光电子能谱技术,详细测量了相变过程其能带结构随温度的演变,揭示了相变过程中Cu2Se的电子结构的剧烈重组.作者利用光电子强度近似的模拟Cu2Se费米能级附近的电子态随温度的演化,并采用Mott模型来估算在相变过程中Seebeck系数的演化,再现了输运实验中Seebeck系数的提升.本研究表明电子结构在体系的热电性质中起了非常重要的作用,为理解和优化材料的热电性能提供了一种可能的方法.

Nano-scale compositional oscillation and phase intergrowth in Cu_(2)S_(0.5)Se_(0.5) and their role in thermal transport

Solid solution alloying is a promising strategy to establish high performance thermoelectrics.By alloying different elements,phase structures and phase compositions may vary accompanied by appearance of variety of interesting microstructures including mass fluctuation,lattice strain,nano-scale defects and spinodal decomposition,all of which may greatly influence the electrical and specifically the thermal transport of the material.In the present study,atomic structures of Cu_(2)S_(0.5)Se_(0.5) solid solution have been examined by using atom-resolved electron microscopy in order to investigate the structure-correlated physical insights for the abnormal thermal transport in this solid solution.Then the exceptional intergrowth nanostructures were observed.The solid solution consists of two high symmetrical phases,i.e.the hexagonal and cubic phase,which alternately intergrow to form highly oriented ultra-thin lamellae of nano or even,unit cell scales.The compositional oscillation in Se/S atomic ratio during alloying is responsible for the phase stability and intergrowth nanostructures.The unique binary phase intergrowth nanostructures make great contribution to the ultra-low lattice thermal conductivity comparable to glass and extremely short phonon mean free path of only 1.04Å,peculiar continuous hexagonal-to-cubic structural transformation without a critical transition temperature and its corresponding abnormal changes of thermal characters with temperatures.The present study further evokes the unlimited possibilities and potentials for tailoring nanostructures by alloying for improved thermoelectric performance.

Step distribution of Yb filling fraction during microstructural evolution in skutterudites

To achieve a better material for thermoelectric power generation device, filled skutterudite Yb0.3 Co_4 Sb_(12) samples were fabricated by melting-quenching-annealing-spark plasma sintering(SPS)method. Two sets of samples, before and after SPS, were investigated. In both the two sets of samples,the average grain size of the samples increases monotonously with the increase of annealing time,while Yb filling fraction firstly increases and then decreases. Yb not filling into the skutterudite remains at the grain boundaries in the form of Yb_2 O_3 after SPS, which could be quantified by the spatially difference method of energy dispersive spectra. Step distribution of Yb filling fraction was observed in the samples annealed for 1 h, which was caused by the microstructural evolution from the peritectic phases to the skutterudite phase. The sample annealed for 3 days and SPS sintered possesses the maximum value of Yb filling fraction 0.249 and the maximum ZT value of 1.24 at 850 K. These results are helpful to better understand the microstructural evolution and Yb filling behavior in skutterudite materials.