Development of Heavy Element Chemistry at Interfaces: Observing Actinide Complexes at the Oil/Water Interface in Solvent Extraction by Nonlinear Vibrational Spectroscopy

Understanding the chemistry of elements at the bottom of the periodic table is a challenging goal in chemistry. Observing actinide species at interfaces by using interface-selective second-order nonlinear optical spectroscopy, such as vibrational sum frequency generation (VSFG) spectroscopy, is a promising route for developing heavy element chemistry; however, such attempts are scarce. Here, we investigated the phase transfer mechanism of uranyl ions (UO22+) in solvent extraction using the di­(2-ethylhexyl)­phosphoric acid (HDEHP) extractant dissolved in the dodecane organic phase by probing the oil/water liquid–liquid interface using VSFG spectroscopy. The POO– symmetric stretch vibrational signals of the HDEHP ligands clearly demonstrated that uranyl ions form interfacial complexes with HDEHP at the oil/water interface. The interfacial uranyl–HDEHP complexes were formed with uranyl ions coming from both the aqueous and oil phases, strongly suggesting that the interfacial complex is an intermediate to cross the oil/water interface. Density functional theory calculations proposed the molecular structure of the interfacial uranyl–HDEHP complex

Establishing an evaluation method for the aging phenomenon by physical force in fuel debris

Fuel debris consisting of nuclear fuel and reactor structural materials generated in the accident in Fukushima Daiichi Nuclear Power Plant can deteriorate similar to rocks when subjected to changes in environmental temperature. Although the fuel debris has been cooled by water for 10 years, they are affected by seasonal and/or day-and-night temperature changes. Therefore, in evaluating the aging behavior of the fuel debris, we need to consider the changes in the environmental temperature. Assuming that the fuel debris was deteriorated, radioactive substances that have recently undergone micronization can be eluted into the cooling water, and such condition may affect the defueling methods. We focused on the effect of repeated changes in environmental temperature on the occurrence of cracks, and an accelerated test using simulated fuel debris was performed. The length of the crack increased with increasing number of heat cycles; therefore, the fuel debris became brittle due to the stress caused by thermal expansion and contraction. In conclusion, we confirmed that the mechanical deterioration of the fuel debris was similar to that of rocks or minerals, and predicting the changes in the length of the crack in the simulated fuel debris and environmental model is possible.</p

Raman identification and characterization of chemical components included in simulated nuclear fuel debris synthesized from uranium, stainless steel, and zirconium

Raman spectroscopy is a powerful technique for studying nuclear materials. However, it has been scarcely utilized for nuclear fuel debris. Here, we present a Raman study of several types of simulated nuclear debris synthesized from uranium, stainless steel, and zirconium to identify and characterize chemical components included in the simulated debris. Raman spectroscopy sensitively identified many kinds of chemical components: cubic UO2, U3O8, (Fe,Cr)UO4 (iron–chromium uranate), spinel oxides, monoclinic ZrO2, tetragonal ZrO2, and Zr3O. Some details concerning the chemical states of each component included in the simulated debris were obtained (e.g. spinel oxides were suggested to consist of Fe, Cr, Ni, Zr, and U). The results obtained here will be helpful in the Raman analysis of actual nuclear debris, such that in the Fukushima Daiichi nuclear power plants.</p

Photoluminescent Dinuclear Lanthanide Complexes with Tris(2-pyridyl)carbinol Acting as a New Tetradentate Bridging Ligand

A tripodal ligand, tris(2-pyridyl)carbinol, affords a novel tetradentate coordination mode in homodinuclear lanthanide complexes, which exhibit remarkably short distances between metal ions. The strong luminescences of Eu(III) and Tb(III) complexes with the ligand demonstrate that the ligand has a suitable excited state for energy transfer from the ligand to the Eu(III) and Tb(III) centers, respectively

Absolute Stereochemistry of Citrinadins A and B from Marine-Derived Fungus

Citrinadin A (2) is a pentacyclic indolinone alkaloid isolated from the cultured broth of a fungus, Penicillium citrinum, which was separated from a marine red alga. The absolute stereochemistry of the pentacyclic core in 2 and its new congener, citrinadin B (1), was elucidated by analysis of the ROESY spectrum for the chlorohydrin derivative (3) of 1 as well as comparison of the electronic circular dichroism (ECD) spectra for 1 and 2 with those of known spirooxiindole alkaloids. On the other hand, the absolute configuration at C-21 bearing an epoxide ring was assigned as S by comparison of the vibrational circular dichroism (VCD) spectra of 1 with those of model compounds 2S- and 2R-2,3-epoxy-3,3-dimethyl-1-phenylpropan-1-one (4a and 4b, respectively)

Photoluminescent Dinuclear Lanthanide Complexes with Tris(2-pyridyl)carbinol Acting as a New Tetradentate Bridging Ligand

A tripodal ligand, tris(2-pyridyl)carbinol, affords a novel tetradentate coordination mode in homodinuclear lanthanide complexes, which exhibit remarkably short distances between metal ions. The strong luminescences of Eu(III) and Tb(III) complexes with the ligand demonstrate that the ligand has a suitable excited state for energy transfer from the ligand to the Eu(III) and Tb(III) centers, respectively

Score for each symptom assessed by the Child Behavior Check List (CBCL).

<p>The patterned gray and white bars indicate the average T-score in children with attention deficit hyperactivity disorder (ADHD; n = 37) and typically developing (TD) children (n = 88), respectively. Numbers on the x-axis denote the CBCL subcategories: 1 = Withdrawn; 2 = Somatic complaints; 3 = Anxious/depressed; 4 = Social problems; 5 = Thought problems; 6 = Attention problems; 7 = Delinquent behavior; 8 = Aggressive behavior; 9 = Internalizing problems; 10 = Externalizing problems; 11 = Total score across all categories. Error bars represent the standard deviation. Asterisks (*) indicate statistically significant differences between the two groups (p < 0.01).</p

Uranium dissolution and uranyl peroxide formation by immersion of simulated fuel debris in aqueous H₂O₂ solution

The fuel debris generated in the accident at the Tokyo Electric Power Company’s Fukushima Daiichi Nuclear Power Station has been subject to water and ionizing radiation for years and will be until retrieval. Therefore, we investigated the potential degradation of this fuel debris caused by H2O2, which is the oxidant of major impact from water radiolysis. We performed leaching experiments on different kinds of simulated debris comprising U, Fe, Cr, Ni, and Zr in an aqueous H2O2 solution. Chemical analysis of the leaching solution showed that U dissolution was induced by H2O2. Raman analysis after the leaching revealed that uranyl peroxides were formed on the surface of the simulated debris. The U dissolution and uranyl peroxide formation were observed in most of the simulated debris. These results demonstrate that uranyl peroxides are possible alteration products of fuel debris from H2O2 reaction. However, the sample in which the main U-containing phase was a U-Zr oxide solid solution showed much less U dissolution and no Raman signal of uranyl peroxides. Comparison of these results indicates that formation of an oxide solid solution of Zr with UO2 improves the stability of fuel debris against H2O2 reaction.</p

Attention Deficit Hyperactivity Disorder Rating Scale (ADHD-RS) score in ADHD children.

<p>The bars indicate the average score on the impulsivity/hyperactivity section of the ADHD-RS, the inattention section of the ADHD-RS, and the total ADHD-RS score for all 37 children with ADHD. Error bars denote the standard deviation.</p

Supplementary Figure 2 from <i>PIK3CA</i> Mutation Is Associated with a Favorable Prognosis among Patients with Curatively Resected Esophageal Squamous Cell Carcinoma

PDF File - 95K, K-M curves according to mutation sites.</p