Adsorption of Zn(II) from aqueous solution and separation of zinc isotopes by displacement chromatography using chelating adsorbent.

The removal of zinc ions (Zn(II)) in water and the separation of zinc isotopes were fully investigated in this study. Imidodiacetic acid (IDA) type adsorbent (named PSGI) based on polystyrene spheres (PS) was synthesized by simultaneous irradiation grafting. By adsorption method, the removal of Zn(II) from water by the chelating adsorbent was studied in batch experiments. Under optimized condition, PSGI showed the removal efficiency of more than 98 % for Zn(II) and the adsorption capacity of 70.1 mg/g. Langmuir isothermal and pseudo-second-order kinetic model fitted the experimental results better, indicating that the adsorption is dominated by chemical adsorption. The spent adsorbent (PSGI-Zn) was used for further zinc isotope separation by displacement chromatography using EDTA-NH4 solution as eluent. Due to the mass effect of isotopes, 70Zn was found to preferentially fractionated into the front-end effluents with the highest front enrichment values of 70Zn/64Zn. By extending the migration distance to 20 m, we obtained the best isotope enrichment with the front maximum enrichment values as 1.0949, 1.0739 and separation coefficient values as 1.977 × 10-3, 8.33 × 10-3 corresponding to the isotope pairs 66Zn/64Zn, 68Zn/64Zn.

Fifty top-cited classic papers in orthopedic elbow surgery: A bibliometric analysis.

OBJECTIVE: The number of citations that a paper has received reflects the impact of the article within a particular medical area. Citation analysis concerning the most cited articles have been widely reported in orthopedic surgery and its subspecialties. However, which articles are cited most frequently in orthopedic elbow surgery is unknown. This study aimed to identify and analyze the characteristics of the 50 most cited articles in elbow surgery. METHODS: Science Citation Index Expanded was used to search for citations in 181 journals chosen according to the relevance for elbow publications. The 50 most cited articles in elbow surgery were identified. The title, authors, year of publications, article type, journal source, country, institution, number of citations, decade published, citation density and level of evidence were recorded and analyzed. RESULTS: The 50 most cited articles were published between 1950 and 2010. The 1980s was the most productive decade. The number of citations ranged from 388 to 124. All the articles were written in English and published in nine journals. The majority of articles originated from United States, followed by Canada and United Kingdom. Fracture was the most discussed topic. The majority of the top cited articles were clinical studies, with the remaining basic research. The most common level of evidence was level IV. CONCLUSIONS: Identification of the most cited papers in elbow surgery shows an insight into the historical development of elbow surgery and provides the foundation for further investigations.

A primary survey on bryophyte species reveals two novel classes of nucleotide-binding site (NBS) genes.

Due to their potential roles in pathogen defense, genes encoding nucleotide-binding site (NBS) domain have been particularly surveyed in many angiosperm genomes. Two typical classes were found: one is the TIR-NBS-LRR (TNL) class and the other is the CC-NBS-LRR (CNL) class. It is seldom known, however, what kind of NBS-encoding genes are mainly present in other plant groups, especially the most ancient groups of land plants, that is, bryophytes. To fill this gap of knowledge, in this study, we mainly focused on two bryophyte species: the moss Physcomitrella patens and the liverwort Marchantia polymorpha, to survey their NBS-encoding genes. Surprisingly, two novel classes of NBS-encoding genes were discovered. The first novel class is identified from the P. patens genome and a typical member of this class has a protein kinase (PK) domain at the N-terminus and a LRR domain at the C-terminus, forming a complete structure of PK-NBS-LRR (PNL), reminiscent of TNL and CNL classes in angiosperms. The second class is found from the liverwort genome and a typical member of this class possesses an α/ß-hydrolase domain at the N-terminus and also a LRR domain at the C-terminus (Hydrolase-NBS-LRR, HNL). Analysis on intron positions and phases also confirmed the novelty of HNL and PNL classes, as reflected by their specific intron locations or phase characteristics. Phylogenetic analysis covering all four classes of NBS-encoding genes revealed a closer relationship among the HNL, PNL and TNL classes, suggesting the CNL class having a more divergent status from the others. The presence of specific introns highlights the chimerical structures of HNL, PNL and TNL genes, and implies their possible origin via exon-shuffling during the quick lineage separation processes of early land plants.