Preface

Owing to the fast economic growing and the concern over greenhouse gases and air pollution,the development of nuclear energy is one important option to meet the expanded energy consumption in our future.To achieve that goal,continuing and reliable supplies of uranium are critical to future nuclear power projects.As is well known,global terrestrial reserves of uranium are limited and the deposits in China are relatively small.Given the projected big growth in nuclear power in the future,reliable supply of uranium at a reasonable price is essential for China.     

A New Method for Selective Deprotection of Anomeric N,O-Dimethylhydroxylamine Promoted by TMSCl

TMSCl was shown to be an efficient reagent for selective deprotection of the anomeric position protected as N,O-dimethylhydroxylamine glycoside. This deprotection condition was proved to be compatible with a number of protecting groups, such as the TBDPS, acetyl, benzyl, benzylidene, and benzoyl groups.     

Improvement of the weighted essentially nonoscillatory scheme based on the interaction of smoothness indicators

The weighted essentially nonoscillatory scheme is improved by introducing new smoothness indicators that evaluate the interactions among the classical smoothness indicators suggested by Jiang and Shu. The effect of the key parameters in the new smoothness indicators on the scheme is systematically investigated. The improved scheme has smaller dissipation with larger weight assignment to the discontinuous stencils and higher numerical accuracy with weights closer to the ideal weights. To verify the theory, benchmark problems governed by the linear transport equation, the 1‐dimensional nonlinear Burgers equation, and the Euler equations are conducted and analyzed, respectively. Better computational performances both on numerical resolution and accuracy are shown in the comparisons with other classical weighted essentially nonoscillatory schemes.     

Construction of Hybrid Bimetallic Uranyl Compounds Based on a Preassembled Terpyridine Metalloligand

Six hybrid uranyl–transition metal compounds [UO₂Ni(cptpy)₂(HCOO)₂(DMF)(H₂O)] ( 1 ), [UO₂Ni(cptpy)₂(BTPA)₂] ( 2 ), [UO₂Fe(cptpy)₂(HCOO)₂(DMF)(H₂O)] ( 3 ), [UO₂Fe(cptpy)₂(BTPA)₂] ( 4 ), [UO₂Co(cptpy)₂(HCOO)₂(DMF)(H₂O)] ( 5 ), and [UO₂Co(cptpy)₂(BTPA)₂] ( 6 ), based on bifunctional ligand 4′-(4-carboxyphenyl)-2,2′:6′,2′′-terpyridine (Hcptpy) are reported (H₂BTPA = 4,4′-biphenyldicarboxylic acid). Single-crystal XRD revealed that all six compounds feature similar metalloligands, which consist of two cptpy⁻ anions and one transition metal cation. The metalloligand M(cptpy)₂ can be considered to be an extended linear dicarboxylic ligand with length of 22.12 Å. Compounds 1 , 3 , and 5 are isomers, and all of them feature 1D chain structures. The adjacent 1D chains are connected together by hydrogen bonds and π–π interactions to form a 3D porous structure, which is filled with solvent molecules and can be exchanged with I₂. Compounds 2 , 4 , and 6 are also isomers, and all of them feature 2D honeycomb (6,3) networks with hexagonal units of dimensions 41.91×26.89 Å, which are the largest among uranyl compounds with honeycomb networks. The large aperture allows two sets of equivalent networks to be entangled together to result in a 2D+2D→3D polycatenated framework. Remarkably, these uranyl compounds exhibit high catalytic activity for cycloaddition of carbon dioxide. Moreover, the geometric and electronic structures of compounds 1 and 2 are systematically discussed on the basis of DFT calculations.     

Design study and heat transfer analysis of a neutron converter target for medical radioisotope production

A worldwide challenge in the near future will be to find a way of producing radioisotopes in sufficient quantity without relying on research reactors. The motivation for this innovative work on targets lies in the accelerator-based production of radioisotopes using a neutron converter target as in the transmutation by adiabatic resonance crossing concept. Thermal analysis of a multi-channel helium cooled device is performed with the computational fluid dynamics code CFX. Different boundary conditions are taken into account in the simulation process and many important parameters such as maximum allowable solid target temperature as well as uniform inlet velocity and outlet pressure changes in the channels are investigated. The results confirm that the cooling configuration works well; hence such a solid target could be operated safely and may be considered for a prototype target.     

Cytotoxic and NF-κB inhibitory sesquiterpene lactones from Piptocoma rufescens

Six new (1-6) and eight known germacranolide-type sesquiterpene lactones, along with several known phenylpropanol coumarates and methylated flavonoids, were isolated from the leaves of Piptocoma rufescens, collected in the Dominican Republic. The new compounds were identified by analysis of their spectroscopic data, with the molecular structure of 3 being established by single-crystal X-ray diffraction. The absolute configurations of the sesquiterpene lactones isolated were determined from their CD and NOESY NMR spectra, together with the analysis of Mosher ester reactions. Bioassay screening results showed the majority of the sesquiterpene lactones isolated (1-13) to be highly cytotoxic toward the HT-29 human colon cancer cell line, with the most potent compound being 15-deoxygoyazensolide (10, IC(50), 0.26 μM). In addition, several of the sesquiterpene lactones exhibited NF-κB (p65) inhibitory activity.     

Silica nanoparticle supported molecularly imprinted polymer layers with varied degrees of crosslinking for lysozyme recognition

Surface imprinting over nanosized support materials is particularly suitable for protein templates, considering the problems with mass transfer limitation and low binding capacity. Previously we have demonstrated a strategy for surface protein imprinting over vinyl-modified silica nanopartiles with lysozyme as a model template by polymerization in high-dilution monomer solution to prevent macrogelation. Herein, the synthesis process was further studied toward enhancement of the imprinting performance by examining the effect of several synthesis conditions. Interestingly, the feed crosslinking degree was found to have a great impact on the thickness of the formed imprinting polymer layers and the recognition properties of the resulting imprinted materials. The imprinted particles with a crosslinking degree up to 50% showed the best imprinting effect. The imprinting factor achieved 2.89 and the specific binding reached 23.3 mg g⁻¹, which are greatly increased compared to those of the lowly crosslinked imprinted materials reported previously. Moreover, the relatively high crosslinking degree led to no significant retarding of the binding kinetics to the imprinted particles, and the saturated adsorption was reached within 10 min. Therefore, this may be a promising method for protein imprinting.