大冶铜绿山矿区周边土壤—水稻中镉赋存状态及转化迁移规律研究

通过对大冶铜绿山矿区周边农田土壤、水稻系统采样分析表明,农田土壤中全量Cd的浓度范围为0.42～1.63 mg/kg,平均值为0.88 mg/kg,土壤中全量Cd含量与易利用态和中等结合态含量有较高的相关系数,相关系数0.8。在水稻籽实(大米)镉积累预测方面,选取土壤中全量Cd、pH、CEC、有机质建立的数学模型能较好地预测大米中Cd的累积。     

淬火硝盐的劣化和再生

使用扫描电镜及能谱分析、化学分析方法,全面分析了使用硝盐浴进行分级淬火和等温淬火时,淬火硝盐劣化产物。结果表明:硝盐反应生成物(Na₂CO₃、NaOH),设备(主要是盐槽、盐泵、管道)、夹具、料盘及工件等氧化产物(FeO·Fe₂O₃·Fe₃O₄),外来物(灰尘,炭黑)是造成硝盐劣化的主要原因。据此,提出了预防淬火硝盐劣化措施:选用品质好的基盐;选用热稳定性较高的混合盐;保持淬火盐浴温度均匀,淬火前后温升可控,尽量避免“瞬间”过热使用;尽量避免外来杂质进入;做好日常维护。并简要介绍了淬火硝盐再生处理方法。     

三乙醇胺对水泥-粉煤灰体系水化进程与强度的影响机制

为掌握三乙醇胺(TEA)水泥-粉煤灰体系水化与强度的影响规律及其机理,促进粉煤灰的有效利用,采用等温量热法测试分析了不同温度条件下TEA对水泥-粉煤灰体系水化放热行为和体系活化能的变化,通过热重和X射线衍射分析了掺TEA水泥-粉煤灰体系的物相组成及其变化,研究了TEA对水泥-粉煤灰体系水化进程和强度的影响规律.结果 表明,TEA和温度均水泥-粉煤灰体系水化放热和强度发展存在较大影响.TEA提高了粉煤灰在72 h内的反应热,促进了水泥-粉煤灰体系早期的水化放热,并且在高温下更加明显,水泥-粉煤灰体系活化能随着TEA掺量增加而降低,TEA对水泥熟料矿物铝酸三钙(C3A)、硅酸三钙(C3S)和硅酸二钙(C2S)在不同龄期内的水化进程影响不同,TEA在早期对C3A熟料的水化具有明显的促进作用,而对C3S和C2S的水化则有延缓作用.     

Advanced visible-light photocatalytic property of biologically structured carbon/ceria hybrid multilayer membranes prepared by bamboo leaves

Biologically structured carbon/cerium dioxide materials are synthesized by biological templates. The microscopic morphology, structure and the effects of different oxidation temperatures on materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) ultraviolet-visible light spectrum (UV–Vis) and X-ray Photoelectron Spectroscopy (XPS). Moreover, by splitting water under visible light irradiation, the hydrogen production is measured to test the photocatalytic property of these materials. The results show that materials made with bamboo biological templates which are immersed in 0.1 mol L^?1 of cerium nitrate solution, then carbonizated in nitrogen (700 °C) and oxidized in air (500–600 °C), can obtain the biological structure of bamboo leaves. The product is in the composition of hybrid multilayer membrane, which one is carbon membrane form plant cell carbonation and another is ceria membrane by nanoparticle self assembly. The best oxidation temperature is 550 °C and the band gap of carbon/cerium dioxide materials synthesized at this optimum oxidation temperature could be reduced to 2.75 eV. After exposure to visible light for 6 h, the optimal hydrogen production is about 302 μmol g^?1, which is much higher than that of pure CeO₂.     

The influence of carbon materials on the absorption performance of polymer-derived SiCN ceramics in X-band

Carbon-containing polymer-derived SiCN ceramics (PDCs-SiCN-C) were successfully fabricated with multi-layer graphene (MLG) and multiwalled carbon nanotubes (MWCNTs) as additives at 1100?°C. The effects of MLG and MWCNTs on the microwave absorption properties of PDCs-SiCN-C ceramics were analyzed. The imaginary permittivity and loss tangent of SiCN-MLG and SiCN-MWCNTs were about 3.4, 0.67 at 11.2?GHz and 3.1, 0.57 at 10.6?GHz, respectively. The minimum reflection loss of SiCN-MLG and SiCN-MWCNTs at 3?mm was ??54?dB and ??48?dB with the effective absorption bandwidth (RL ≤ ?10?dB, >90% absorption) about 1.5?GHz and 0.9?GHz in X-band.     

Separation of Methane and Carbon Dioxide Gas Mixtures Using Activated Carbon Modified with 2‐Methylimidazole

Activated carbon was modified by loading 2‐methylimidazole (mIm), ethanol, and glycol onto its surface and adopted to capture CO₂ using the absorption‐adsorption method. The modified activated carbon showed high selectivity for separating CH₄+CO₂ gas mixtures, compared with other methods to modify activated carbon given in the literature. The separation factor was 4.75 times higher than that for the fresh activated‐carbon system, and the separation performance of the activated carbon increased with increasing amount of mIm. The addition of glycol showed greater potential to enhance the selectivity of the activated carbon than ethanol. A recycling test verified the stability of the modified activated carbon for CH₄+CO₂ gas mixture separation.     

Preparation of ZrC/SiC porous self-supporting monoliths via sol-gel process using polyethylene glycol as phase separation inducer

We present a straightforward method via sol-gel process using polyethylene glycol (PEG) as phase separation inducer to prepare zirconium carbide/silicon carbide (ZrC/SiC) porous monoliths. Organic/inorganic hybrid gels are prepared using zirconium oxychloride, furfuryl alcohol, and tetraethyl orthosilicate as major starting materials. In the presence of PEG, crack-free hybrid monoliths are obtained by drying the wet gels under ambient pressure, whereas in the absence of PEG, the wet gels break into pieces as expected. PEG plays a key role in maintaining the macroscopic shape of the monoliths. After ceramization at 1300–1500?°C, ZrC/SiC porous monoliths are obtained. SEM and mercury intrusion porosimetry data show that PEG also has strong influence on the microstructures of the monoliths. The compressive strengths of the ceramic monoliths are in the range of 0.3 to 0.7?MPa. And their compressive behavior starts to differ due to the changes in their microstructures, especially the pore structure.     

Enhanced relative permittivity in niobium and europium co-doped TiO2 ceramics

The appearance of colossal permittivity materials broadened the choice of materials for energy-storage applications. In this work, colossal permittivity in ceramics of TiO₂ co-doped with niobium and europium ions ((Eu_0.5Nb_0.5)_xTi_1-xO₂ ceramics) was reported. A large permittivity (ε_r ～ 2.01?×?10⁵) and a low dielectric loss (tanδ ～ 0.095) were observed for (Eu_0.5Nb_0.5)_xTi_1-xO₂ (x?=?1%) ceramics at 1?kHz. Moreover, two significant relaxations were observed in the temperature dependence of dielectric properties for (Eu, Nb) co-doped TiO₂ ceramics, which originated from defect dipoles and electron hopping, respectively. The low dielectric loss and high relative permittivity were ascribed to the electron-pinned defect-dipoles and electrons hopping. The (Eu_0.5Nb_0.5)_xTi_1-xO₂ ceramic with great colossal permittivity is one of the most promising candidates for high-energy density storage applications.     

A new method to improve the electrical properties of KNN-based ceramics: Tailoring phase fraction

Although both the phase type and fraction of multi-phase coexistence can affect the electrical properties of (K,Na)NbO₃ (KNN)-based ceramics, effects of phase fraction on their electrical properties were few concerned. In this work, through changing the calcination temperature of CaZrO₃ powders, we successfully developed the 0.96 K_0.5Na_0.5Nb_0.96Sb_0.04O₃-0.01CaZrO₃-0.03Bi_0.5Na_0.5HfO₃ ceramics containing a wide rhombohedral-tetragonal (R-T) phase coexistence with the variations of T (or R) phase fractions. It was found that higher T phase fraction can warrant a larger piezoelectric constant (d₃₃) and d₃₃ also showed a linear variation with respect to tetragonality ratio (c/a). More importantly, a number of domain patterns were observed due to high T phase fraction and large c/a ratio, greatly benefiting the piezoelectricity. In addition, the improved ferroelectric fatigue behavior and thermal stability were also shown in the ceramics containing high T phase fraction. Therefore, this work can bring a new viewpoint into the physical mechanism of KNN-based ceramics behind R-T phase coexistence.     

A Bio‐Inspired and Biomass‐Derived Healable Photochromic Material Induced by Hierarchical Structural Design

Utilization of bionics to develop stimuli responsive polymers that can heal damage with excellent restorability is particularly attractive for a sustainable society. Herein, inspired by chameleons, a hierarchical structural design strategy is proposed and illustrated to fabricate a healable photochromic material based on a self‐healable polymeric matrix and a finely dispersed photochromic spirooxazine. The self‐healable polymeric matrix is fabricated via the integration of multiple hydrogen bonds (H bonds) and covalent cross‐links into a biomass‐derived elastomer. The dynamic nature and soft characteristics enable the as‐prepared elastomer superior extensibility as well as self‐healing ability, while the covalent cross‐links can assist the reassociation of ruptured H bonds. The representative elastomer exhibits an extensibility of 2600% and toughness of 42.76 MJ m^?3. Furthermore, it shows good self‐healing ability with complete recovery of scratch as well as restoration against 1900% of elongation and 24.1 MJ m^?3 of toughness after healing at 60 °C for 24 h. This combination of moderate toughness, good self‐healing ability, and smart photochromic property in biomass‐derived materials should largely improve their applicability, reliability, and sustainability in various materials and devices.