CARBEX process,a new technology of reprocessing of spent nuclear fuel

Advances in the CARBEX process, a new aqueous chemical method for reprocessing of spent nuclear fuel (SNF) in carbonate media, are considered. A review of carbonate methods for SNF reprocessing is given. The CARBEX process concept is presented and experimental data for every stage of the CARBEX process: high-temperature oxidation of spent fuel composition, its oxidative dissolution in carbonate aqueous solutions, extraction refining of U(VI) and Pu(VI), solid-phase re-extraction of carbonate complexes of U(VI) and Pu(VI), and obtaining of uranium and plutonium dioxide powders for fabrication of ceramic nuclear fuel, are discussed. It was shown that the CARBEX process can be more effective and safe than the well-known industrial PUREX process.     

Ligand- and anion-directed assembly of exo-coordinated mercury(II) halide complexes with O2S2-donor macrocycles

Assembly reactions of mercury(II) halides (Cl, Br, and I) with two O2S2 macrocycles (L(1) and L(2)) having different interdonor (S...S) distances were investigated, and four types of supramolecular complexes (1-4b) were obtained depending on the S...S distances as well as the size of the halide anions. Photoluminescence of these compounds was also studied.     

Hydrothermal Synthesis of Platinum‐Group‐Metal Nanoparticles by Using HEPES as a Reductant and Stabilizer

Platinum‐group‐metal (Ru, Os, Rh, Ir, Pd and Pt) nanoparticles are synthesized in an aqueous buffer solution of 4‐(2‐hydroxyethyl)‐1‐piperazineethanesulfonic acid (HEPES) (200 mM , pH 7.4) under hydrothermal conditions (180 °C). Monodispersed (monodispersity: 11–15 %) metal nanoparticles were obtained with an average particle size of less than 5 nm (Ru: 1.8±0.2, Os: 1.6±0.2, Rh: 4.5±0.5, Ir: 2.0±0.3, Pd: 3.8±0.4, Pt: 1.9±0.2 nm). The size, monodispersity, and stability of the as‐obtained metal nanoparticles were affected by the HEPES concentration, pH of the HEPES buffer solution, and reaction temperature. HEPES with two tertiary amines (piperazine groups) and terminal hydroxyl groups can act as a reductant and stabilizer. The HEPES molecules can bind to the surface of metal nanoparticles to prevent metal nanoparticles from aggregation. These platinum‐group‐metal nanoparticles could be deposited onto the surface of graphite, which catalyzed the aerobic oxidation of alcohols to aldehydes.     

Synthesis and structures of heteroleptic silylenes

The reaction of benzamidinato silicon trichloride [{PhC(NR)2}SiCl3] [R = Bu(t) (1), SiMe3 (2)] with 2 equiv of potassium in THF afforded mononuclear chlorosilylene [{PhC(NBu(t))2}SiCl] (3) and [{PhC(NSiMe3)2}2SiCl2] (4), respectively. Compound 4 was formed by the disproportionation of unstable [{PhC(NSiMe3)2}SiCl]. The reaction of [{PhC(NBu(t))2}SiCl3] (1) with 1 equiv of LiR (R = NMe2, OBu(t), OPr(i), PPr(i)2) in THF yielded [{PhC(NBu(t))2}SiCl2R] [R = NMe2 (5), OBu(t) (6), OPr(i) (7), PPr(i)2 (8)]. Treatment of 5-8 with 2 equiv of potassium in THF resulted in the novel heteroleptic silylene [{PhC(NBu(t))2}SiR] [R = NMe2 (9), OBu(t) (10), OPr(i) (11), PPr(i)2 (12)]. Compounds 4, 9, and 12 have been analyzed by X-ray crystallography.     

Group II Metal Complexes of the Germylidendiide Dianion Radical and Germylidenide Anion

The two‐electron reduction of a Group 14‐element(I) complex [RË?] (E=Ge, R=supporting ligand) to form a novel low‐valent dianion radical with the composition [RË:]^{. 2?} is reported. The reaction of [LGeCl] ( 1 , L=2,6‐(CH?NAr)₂C₆H₃, Ar=2,6‐iPr₂C₆H₃) with excess calcium in THF at room temperature afforded the germylidenediide dianion radical complex [LGe]^{. 2?}?Ca(THF)₃²⁺ ( 2 ). The reaction proceeds through the formation of the germanium(I) radical [LGe?], which then undergoes a two‐electron reduction with calcium to form 2 . EPR spectroscopy, X‐ray crystallography, and theoretical studies show that the germanium center in 2 has two lone pairs of electrons and the radical is delocalized over the germanium‐containing heterocycle. In contrast, the magnesium derivative of the germylidendiide dianion radical is unstable and undergoes dimerization with concurrent dearomatization to form the germylidenide anion complex [C₆H₃‐2‐{C(H)?NAr}Ge‐Mg‐6‐{C(H)‐NAr}]₂ ( 3 ).     

Optical properties of CH3NH3PbI3 crystal grown using inverse temperature crystallization

Perovskite CH₃NH₃PbI₃ (MAPbI₃) single crystal was grown using inverse temperature crystallization method. Crystallinity of the perovskite was confirmed by X-ray diffraction. Photoluminescence (PL) spectra revealed abnormal behavior due to a temperature-induced orthorhombic to the tetragonal phase transition. Four PL emission peaks, A, B, C, and D, were observed in the low temperature regime. Peaks A and B were observed at 756 and 776?nm?at 12?K, and were blue-shifted and disappeared at 130 and 70?K, respectively. Peaks C and D were observed at 789 and 807?nm?at 40?K and were also blue-shifted to 780 and 794?nm?at 100?K. On the other hand, the peak C red-shifted to 799?nm from 100 to 140?K because of an orthorhombic to the tetragonal phase change and was also blue-shifted above 140?K. From the excitation intensity- and temperature-dependent PL results, peaks A and B were assigned to the free-exciton and bound-exciton of the orthorhombic phase crystal, respectively. In addition, peaks C and D were associated with the free-exciton and bound-exciton of the tetragonal phase crystal, respectively. The activation energy of peak C was calculated to be 98?meV from temperature dependence of the PL intensity.     

Rapid screening of mixed edible oils and gutter oils by matrix-assisted laser desorption/ionization mass spectrometry

Authentication of edible oils is a long-term issue in food safety, and becomes particularly important with the emergence and wide spread of gutter oils in recent years. Due to the very high analytical demand and diversity of gutter oils, a high throughput analytical method and a versatile strategy for authentication of mixed edible oils and gutter oils are highly desirable. In this study, an improved matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) method has been developed for direct analysis of edible oils. This method involved on-target sample loading, automatic data acquisition and simple data processing. MALDI-MS spectra with high quality and high reproducibility have been obtained using this method, and a preliminary spectral database of edible oils has been set up. The authenticity of an edible oil sample can be determined by comparing its MALDI-MS spectrum and principal component analysis (PCA) results with those of its labeled oil in the database. This method is simple and the whole process only takes several minutes for analysis of one oil sample. We demonstrated that the method was sensitive to change in oil compositions and can be used for measuring compositions of mixed oils. The capability of the method for determining mislabeling enables it for rapid screening of gutter oils since fraudulent mislabeling is a common feature of gutter oils.     

Electron-Poor Acridones and Acridiniums as Super Photooxidants in Molecular Photoelectrochemistry by Unusual Mechanisms

Electron-deficient acridones and in situ generated acridinium salts are reported as potent, closed-shell photooxidants that undergo surprising mechanisms. When bridging acyclic triarylamine catalysts with a carbonyl group (acridones), this completely diverts their behavior away from open-shell, radical cationic, ‘beyond diffusion’ photocatalysis to closed-shell, neutral, diffusion-controlled photocatalysis. Brønsted acid activation of acridones dramatically increases excited state oxidation power (by +0.8 V). Upon reduction of protonated acridones, they transform to electron-deficient acridinium salts as even more potent photooxidants (*E_1/2=+2.56–3.05 V vs SCE). These oxidize even electron-deficient arenes where conventional acridinium salt photooxidants have thusfar been limited to electron-rich arenes. Surprisingly, upon photoexcitation these electron-deficient acridinium salts appear to undergo two electron reductive quenching to form acridinide anions, spectroscopically-detected as their protonated forms. This new behaviour is partly enabled by a catalyst preassembly with the arene, and contrasts to conventional SET reductive quenching of acridinium salts. Critically, this study illustrates how redox active chromophoric molecules initially considered photocatalysts can transform during the reaction to catalytically active species with completely different redox and spectroscopic properties.     

A New Photoluminescent Conjugated Poly(1‐hexyl‐3,4‐dimethyl‐2,5‐pyrrolylene): Synthesis,Properties and Characterization

Oxidative coupling reaction of 1‐hexyl–3,4‐dimethylpyrrole affords a conjugated conducting poly(1‐hexyl‐3,4‐dimethyl‐2,5‐pyrrolylene) (PHDP), which is completely soluble in common organic solvents. The luminescence of PHDP is comparable to that of poly(N‐vinylcarbazole) (PVK), which has been widely used in electroluminescence devices. The quantum efficiency of PHDP is 2.5 times higher than that of PVK. A rationalization is presented relating the conductivity of PHDP to its polymer structure.