Synthesis and characterization of G/TiO1.80 bulk composite thermoelectric material under high temperature and high pressure

The primary purpose of this work is to introduce the second phase of graphene (G) into non-stoichiometric TiO_1.80 successfully and optimize the thermoelectric properties of this composite material through high pressure and high temperature (HPHT) technology. The purpose of doping Ti powder under high pressure is to create a closed reducing atmosphere to change the ratio of titanium to oxygen in the titanium oxide base. The addition of graphene can considerably improve the electrical properties of the material and reduce its resistivity. An X-ray diffractometer, X-ray photoelectron spectrometer, scanning electron microscope, and transmission electron microscope were used to analyze and characterize the phase structure, chemical bond, micro morphology and crystal morphology of the samples. An abundance of grain boundaries and lattice dislocation defects can inhibit the lattice thermal conductivity. We also tested and analyzed the thermoelectric performance of the high-temperature and high-pressure synthetic samples through a variable temperature system. The variation of the absorption intensity of the ultraviolet UV spectrum with wavelength shows that high pressure can reduce the band gap, which is beneficial to the carrier transition and improves the conductivity of semiconductors. HPHT optimizes both the electrical and the thermal parameters of the sample. At a final sintering pressure of 5.0 GPa, the dimensionless figure of merit (zT) of the bulk composite material G/TiO_1.80 was found to be 0.23 at 700 °C.     

纳米Co/rGO磁性复合吸附材料的制备及对Cu2+的吸附性能

以改进Hummer法制备的薄片状氧化石墨烯(GO)为载体和模板负载钴离子，然后采用原位还原法制得纳米金属Co/石墨烯磁性复合吸附材料(Co/rGO)，并将其应用于对Cu2+的吸附和脱除，以期为高效可复用的铜离子脱除剂的合成与应用提供指导。实验结果证实，Co/rGO复合材料具有超顺磁性，能够很方便的使用磁铁进行分离并在无磁场情况下振荡分散。Co/rGO复合材料对Cu2+具有稳定的吸附/脱附性能，实验条件下对Cu2+的最大吸附容量达到117.5 mg/g且5 min内实现吸附平衡，远优于其原料GO的60 min吸附容量27.6 mg/g。本工作系统考察了NaOH加入量、络合剂种类、溶剂种类等关键因素对Co粒子在rGO载体上形貌和分布特性的影响，比较了不同合成条件下的复合材料对Cu2+吸附效果的影响，并对优选条件下制备的Co/rGO复合材料进行了FT-IR, XRD, SEM表征。研究结果表明，纳米Co/rGO磁性材料对Cu2+的吸附过程更符合Freundlich模型，属于多层吸附。室温下吸附焓ΔH=17.81 kJ/mol，吸附反应平衡常数Kθ=3.65。当初始Cu2+浓度为39.22 mg/L时，对Cu2+的吸附率为93.47%，五次吸附/脱附循环后吸附容量仍保持在初始值的94%，每次吸附后溶液中残余Cu2+浓度均满足钴电解液对杂质铜离子的浓度去除要求(5 mg/L)或GB 8978-1996污水综合排放标准3级(2 mg/L)，有望在相关领域发挥作用。     

基于微量元素多元统计和微观形态分析的花椒叶产地及品种判别

为解决不同产地、品种花椒叶混售的问题,采用湿法消解结合电感耦合等离子体发射光谱(ICP-OES)技术同步检测不同产地、品种的12个样品中的Ba、Ce、Ho等10种微量元素。利用主成分分析与聚类分析对数据进行研究,结果表明：2个主成分贡献率达到70%,样品可显著聚类为2类,伏椒叶与油椒叶的元素含量差异显著,不同产地的花椒叶也能明显区分。基于扫描电镜(Scanning electron microscope , SEM)的微观形态分析佐证了多元统计分析的结论,伏椒叶与油椒叶结构差异显著,不同产地的花椒叶表现出的结构差异性或相似性都符合统计分析的分类结果。研究能够有效的判别不同产地、品种的花椒叶。     

TCS微孔化新合纤微观形态与性能研究

主要研究了碱减量处理后的微孔化新合纤中的微孔穴形态及其分布与纤维的保水率、上染率及力学性能 之间的内在联系,探讨了无机纳米颗粒对微孔穴形态结构与纤维质量的影响。     

土壤胶膜的研究进展

土壤胶膜是土壤中普遍存在的形成物,其性质与整个土体有较大的变异和不同,对土壤的物质流和能量流、生产力和植物营养以及土壤质量等有重要影响。本文从土壤胶膜的成因、分类、微形态特征、物质组成及其对土壤性质的影响,土壤胶膜与土壤发生与分类、古气候等的关系,探讨了土壤胶膜的研究进展,并展望了以后可能的研究趋势。     

Influence of the microstructure in the collapse of a residual clayey tropical soil

A typical residual clayey soil originating from basalt in southern Brazil has been analyzed in order to assess the influence of wetting-induced deformation and microstructural features on the collapse behavior. Single and double oedometer tests were undertaken on a soil profile to 9 m depth. The results indicated collapsible behaviour at all profile depths. The influence of pre-consolidation stress and pedogenetic factors in the variability of the physical characteristics of the soil and in the magnitude of the collapse was noted. The collapse coefficient has been shown to be related to the both the microaggregate plasma and the varying nature of the pores and their interconnectivity.      

Alumina aerogels with unidirectional channels under different freezing temperatures during freeze casting—Part I: Control and analysis of pore channels

Unidirectional alumina aerogels (AAs) were prepared by simultaneously using boehmite hydrosols and alumina nano-powder as solid solutes at different freezing temperatures. In order to understand the porous structural characteristics under different freezing parameters, the real-time frozen parameters were recorded at the designated positions under different freezing temperatures. Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) were used to investigate the functional groups, phase composites, microstructures and porous characteristics. The regularities and influence factors of unidirectional porous structures of AAs were detailedly explored under different frozen parameters. The results show that the AAs are characterized with unidirectional porous structures at the direction of ice-crystal growth. The cooling rate and ice front rate (v_inf) increase and the structure wavelengths (λs) decrease with the decrease of the freezing temperature. The relationship between λ and v_inf approximately satisfies a power law, which perhaps is related to the uniform dilute solution containing nanoparticle.     

Structure and Micromorphology of Wear Debris of MC Nylon 6 under Dry Sliding: Correlation with Wear Mechanisms

The structure and micromorphology of wear debris of MC nylon 6 under dry sliding were investigated by FTIR, XRD, DSC, and FESEM, and the 3D surface topographies of friction materials before and after the friction test were observed, which will be helpful in understanding the friction and wear processes. The primary crystalline phase of both the unworn MC nylon 6 and the wear debris were α crystal, but the crystallinity of the latter was higher than that of the former. The proportion of α ₂ (002 + 202) planes increased and the reflection from the α ₁ (200) planes was suppressed in the wear debris, indicating a preferential arrangement of α ₂ (002 + 202) on the surface of the wear debris. The transition in structure of the wear debris originated from the activation of the chain segments due to the thermodynamic effects. The thermodynamic effects and high chain segment mobility resulted in the hydrogen bonding whose interchain distance is a larger rupture or even chain scission. MC nylon 6 was severely worn due to the contribution of the tearing force that resulted from the combined action of the tribo-interface adhesion and the shearing effect during friction, whereas no damage happened on the worn surface of the counterpart steel pin even if under severe sliding conditions.     

聚苯胺/聚丙烯腈共混体系的微观结构与流变性能研究

首先由乳液聚合制备十二烷基苯磺酸(DBSA)掺杂的聚苯胺(PANI),然后以三氯甲烷/二甲基亚砜 (DMSO)为混合溶剂,制备不同组成的PANI-DBSA/PAN的共混溶液。对共混溶液的流变性能进行了测试, 并研究了共混体系的微观结构与流变性能的关系。     

Direct image-based fractal characterization of micromorphology of calcium carbonate fouling crystals

Researches on macroscopic fouling behavior and micromorphology are usually conducted separately. In this paper, the relationship between the macroscopic fouling behavior and micromorphology on different materials is established. A direct fractal-characterization approach based on the micrographs of calcium carbonate fouling crystals is presented. The box-counting method is used to characterize the fouling crystals. For fractal measurements, t-distribution tests of linear regression hypothesis are performed at the significance level of 0.01. If all listed absolute t-statistics with the minimum of 164 are higher than the corresponding t value, the fouling crystals are determined as fractal, with a confidence level of 99%. The fractal dimensions obtained from the micrographs of different visual fields of a specimen are demonstrated to be almost identical, with maximum and minimum relative values of 4.42% and 0.75%, respectively, and standard deviations ranging from 0.0062 to 0.0266. The irregularity of the crystal morphology indicates larger fractal dimensions. Comparison and analysis of the relationship between macroscopic fouling behavior and micromorphology show that the larger fractal dimension of crystal morphology suggests a small amount of surface fouling. Thus, the reasons for the differences in the macroscopic fouling behaviors of different materials are revealed geometrically.