Complexation of lactate with neodymium(III) and europium(III) at variable temperatures: studies by potentiometry, microcalorimetry, optical absorption, and luminescence spectroscopy

The complexation of neodymium(III) and europium(III) with lactate was studied at variable temperatures by potentiometry, absorption spectrophotometry, luminescence spectroscopy, and microcalorimetry. The stability constants of three successive lactate complexes (ML(2+), ML(2)(+), and ML(3)(aq), where M stands for Nd and Eu and L stands for lactate) at 10, 25, 40, 55, and 70 °C were determined. The enthalpies of complexation at 25 °C were determined by microcalorimetry. Thermodynamic data show that the complexation of trivalent lanthanides (Nd(3+) and Eu(3+)) with lactate is exothermic and the complexation becomes weaker at higher temperatures. Results from optical absorption and luminescence spectroscopy suggest that the complexes are inner-sphere chelate complexes in which the protonated α-hydroxyl group of lactate participates in the complexation.     

全固态介观太阳能电池:从染料敏化到钙钛矿

介观太阳能电池(Mesoscopic Solar Cells)作为新一代太阳能电池的突出代表, 具有原材料来源丰富, 制备工艺简单, 光电转换效率高等优点, 从而具有广阔的应用前景. 本工作简要评述了全固态介观太阳能电池从染料敏化太阳能电池(Dye-sensitized solar cells)发展到钙钛矿太阳能电池(Perovskite solar cells)过程中新材料、新技术和新概念的研究进展. 1998年, Grätzel课题组首次将固态有机空穴传输材料spiro-OMeTAD应用到染料敏化太阳能电池中, 制备出全固态染料敏化太阳能电池, 虽然仅获得了0.74%的光电转换效率, 但是却使得全固态染料敏化太阳能电池迅速发展成为介观太阳能电池的重要研究方向. 2012年, Park与Grätzel课题组合作, 使用钙钛矿型吸光材料(CH₃NH₃)PbI₃作为敏化剂, spiro-OMeTAD作为空穴收集层, 制备出光电转换效率达到9.7%的全固态介观太阳能电池, 又被称为钙钛矿太阳能电池. 自此, 基于钙钛矿材料的介观太阳能电池迅速成为太阳能电池领域的研究热点. 目前, 钙钛矿太阳能电池的最高公证效率已经达到20.1%. 钙钛矿太阳能电池作为介观太阳能电池商业化道路上里程碑式的突破, 在材料开发、界面优化以及器件稳定性方面的研究仍充满挑战, 也期待新的突破.     

Thermodynamics of neptunium(V) complexes with phosphate at elevated temperatures

The complexation of Np(V) with phosphate at elevated temperatures was studied by a synergistic extraction method. A mixed buffer solution of TRIS and MES was used to maintain an appropriate pH value during the distribution experiments. The distribution ratio of Np(V) between the organic and aqueous phases was found to decrease as the concentrations of phosphate were increased. Stability constants of the 1:1 and 1:2 Np(V)-HPO₄ ²⁻ complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of [HPO₄ ²⁻] on the distribution ratio. The thermodynamic parameters including enthalpy and entropy of complexation between Np(V) and HPO₄ ²⁻ at 25 °C–55 °C were calculated by the temperature coefficient method.     

酚醛基电纺纤维的制备和分散形态研究

用电纺技术制备了酚醛纤维及碳纤维.用合成的甲阶酚醛(A-stage resol)和聚乙烯醇(PVA)在不同配比下进行电纺,然后经150℃固化处理1h,制得酚醛(PF)纤维.将PF和PVA质量比为1∶2的酚醛纤维在不同的温度下进行热处理,得到的纤维直径均小于200nm.用场发射扫描电镜(FESEM)观察并比较了纤维的直径和分散形态.用红外光谱(IR)证实了,在600℃下热处理后的酚醛纤维为碳纤维,分散形态最为理想.     

Synthesis and characterization of pyridyl anion exchange resin for 99Tc removal

Journal of Radioanalytical and Nuclear Chemistry - A new pyridyl anion exchange resin (PS-N) was synthesized by chloroacetylation and quaternization on the polystyrene-divinylbenzene microspheres...     

Quest for Environmentally Benign Ligands for Actinide Separations: Thermodynamic,Spectroscopic, and Structural Characterization of UVI Complexes with Oxa‐Diamide and Related Ligands

Complexation of U ^VI with N,N,N′,N′‐tetramethyl‐3‐oxa‐glutaramide (TMOGA) and N,N‐dimethyl‐3‐oxa‐glutaramic acid (DMOGA; see picture) was studied in comparison with their dicarboxylate analogue, oxydiacetic acid (ODA). The stability constants, enthalpy, and entropy of complexation all decrease in the order ODA> DMOGA>TMOGA, showing that the complexation is entropy driven and the substitution of a carboxylate group with an amide group reduces the strength of complexation with U^VI due to the decrease in the entropy of complexation (see figure).

     

Solubility and solubility product of crystalline Ni(OH)2

The solubility of crystalline Ni(OH)₂ was studied in solutions of 0.01M NaC10₄ with pH ranging from 7 to near 14. Equilibrium was approached both from over-and undersaturation, and the equilibration times extended from 3 to 90 days. The solubility of Ni(OH)₂(c) in the pH range of approximately 7 to 11.3 was effectively modeled by including aqueous Ni²⁺ and NiOH⁺ species. Values of the logarithm of the thermodynamic equilibrium constants for the reactions [Ni(OH)₂(c) ⇌ Ni²⁺ + 2OH^-] and [Ni²⁺ + OH^- ⇌ Ni(OH)⁺] were determined to be -16.1±0.1 and 5.65 ± 0.10, respectively. These data, in conjunction with Pitzer ion interaction parameters given in the literature, were used to model the reported solubilities of Ni(OH)₂(c) in chloride, sodium acetate, and potassium chloride solutions. The model predictions for these systems were in excellent agreement with the experimental data from the literature.     

改良黄土强度特性与工程处置试验研究

本文针对山西朔州典型黄土,利用素黄土与石灰粉煤灰、石灰水泥、水泥粉煤灰三种改良黄土,进行了击实特性、抗剪强度特性及崩解特性试验研究,提出了黄土改良的最佳方案,并采用该方案对山西某煤矿电梯井填方段进行了数值模拟分析,验证了石灰粉煤灰改良黄土工程应用的可行性。试验结果表明:粉煤灰与黄土形成致密的混合结构,石灰的掺入,激活了粉煤灰的活性,发生了一系列的水化反应,使改良黄土的强度大大提高,改良黄土在物理力学性质方面有明显改善。     

Influence of surface recombination and interface states on the performance of β-FeSi2/c-Si heterojunction solar cells

To explore the origin of low conversion efficiency for novel β-FeSi₂/c-Si heterojunction solar cells, the effect of surface recombination and interface states on the cell performance has been investigated by numerical simulation. The present results show that surface recombination of β-FeSi₂ film plays an important role in limiting the cell property since the photovoltaic behavior of β-FeSi₂ is quite sensitive to surface recombination due to its especial characteristic of very high optical absorption coefficient. Surface quality of β-FeSi₂ film should be much improved for better cell performance. In addition, it is shown that interface states between β-FeSi₂ film and crystalline silicon are critical to device characterization. Interface states should be minimized to obtain higher conversion efficiency. If surface recombination and interface states can be best suppressed, potential conversion efficiency for the cell may be up to 28.12% at 300 K under illumination of AM 1.5, 100 mW/cm².     

STUDY ON THE CATIONIC POLYMERIZATION OF 1, 3-PENTADIENE INITIATED BY AlCl_3/ALKYL HALIDE SYSTEMS

The cationic polymerizations of 1, 3-pentadiene were initiated by AlCl_3 in n-hexaneat 30℃ in the presence of alkyl halides, i.e., tert-butyl chloride, tert-butyl bromide andisobutyl chloride. The effects of these halides on the polymer yield, molecular weight,crosslinking reaction, cyclization and polymer microstructure, have been investigated. Twomain side reactions, crosslinking and cyclization, were suppressed and reduced by theaddition of the halides. The proportion of 1, 4 units of polymer chains was increasedby the presence of the halides, which reduced the polymer yield and the molecular weightof polymers.