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Cationic methylpalladium complexes bearing hemilabile bidentate α-amino–pyridines can serve as effective precursors for catalytic alternating copolymerization of norbornene (N) and ethylene (E), under mild conditions. The norbornyl palladium complexes in the formula of {[RHNCH2(o-C6H4N)]Pd(C7H10Me)(NCMe)}(BF4) (R = iPr (2a), tBu (2b), Ph (2c), 2,6-Me2C6H3 (2d), 2,6-iPr2C6H3 (2e)) were synthesized via single insertion of norbornene into the corresponding methylpalladium complexes 1a–1e, respectively. Both square planar methyl and norbornyl palladium complexes exhibit facile equilibria of geometrical isomerization, via sterically-controlled amino decoordination–recoordination of amino–pyridine. Kinetic studies of E-insertion, N-insertion of complexes 1 and 2, and the geometric isomerization reactions have been examined by means of VT-NMR, and found in excellent agreement with the results estimated by DFT calculations. The more facile N-insertion in the cis-isomers, and ready geometric isomerization, cooperatively lead to a new mechanism that accounts for the novel catalytic formation of alternating COC.

Motivation The Full-text index in Minute space (FM-index) is a memory-efficient data structure widely used in bioinformatics for solving the fundamental pattern-matching task of searching for short patterns within a long reference. With the demand for short query patterns, the k -ordered concept has been proposed for FM-indexes. However, few construction algorithms in the state of the art fully exploit this idea to achieve significant speedups in the pan-genome era. Results We introduce the k -ordered induced suffix sorting (kISS) for efficient construction and utilization of k -ordered FM-indexes. We present an algorithmic workflow for building k -ordered suffix arrays, incorporating two novel strategies to improve time and memory efficiency. We also demonstrate the compatibility of integrating k -ordered FM-indexes with locate operations in FMtree. Experiments show that kISS can improve the construction time, and the generated k -ordered suffix array can also be applied to FMtree without any additional in computation or memory usage. Availability and implementation https://github.com/jhhung/kISS. [ABSTRACT FROM AUTHOR]

A new ligand with N8O2 donors containing three potential metalbinding sites (H2L) and its tricopper(II) complex 1 are synthesized. The tricopper species is found to be formed from a hypodentate dicopper(II) complex 2 in basic solutions. Complex 2 may be isolated from the reaction of H2L with a copper source under acidic conditions. Complex 2 can undergo CO2-abstraction to yield an octacopper(II) complex 3. The single crystal structures of complexes 2 and 3 are characterized by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Cationic methylpalladium complexes with hemilabile bidentate ligands of α-amino-pyridines, in the form of {[R1HNCR2H(o-C6H5N)]Pd(Me)(NCMe)}(BF4) (R1= iPr, tBu, Ar R2= H, Me) have been found to be effective precursors for catalytic copolymerization of ethylene and norbornene under mild conditions. The copolymer products exhibit predominant alternating microstructures which are evidenced by NMR and mass spectrometry as well as a kinetic analysis according to the Finman-Ross relationship. [ABSTRACT FROM AUTHOR]

Ethylene polymerization catalyzed by Ni(II) complexes that bear new bidentate ligands with a functional hybrid of amine and imine has been studied. A class of new α-aminoaldimines and their nickel complexes [R1R2NCMe2CH=N(2,6-R32C6H3)]NiBr2 (R1 = R2 = Me, R3 = Me (Ni-1b); R3 = iPr (Ni-1c); 1 = R2 = Et, R3 = H (Ni-2a); Me (Ni-2b); iPr (Ni-2c); R1 = R2 = nPr, R3 = iPr (Ni-3c); (R1R2) = c-C3H6 R3 = tPr (Ni-4c); (R1R2) = c-C4H8, R3 = iPr (Ni-5c)) were synthesized. The molecular structures of six nickel complexes were determined by X-ray crystallography, showing distorted tetrahedral configurations. The SQUID data of Ni-1c confirms its ground state of triplet spin. Using methylaluminoxanes (MAO) as the activator, the nickel complexes are found to catalyze ethylene polymerization under moderate pressure and ambient temperature. The activity reaches to 106 g PE mol Ni-1 h-1, and increases with the ethylene pressure in the range of 14-28 bar. The highly branching PE products have Mn ∼ 105 with PDI < 2. The amine and imine functionalities demonstrate independent control to the polymerization reactions, wherein the activity appears to be facilitated by using the catalysts installed with bulky imino substituents as well as with less sterically hindered amino substituents. This is ascribed to the C2 unsymmetric coordination in the square planar resting state in which the bulky polymer chain prefers cis to the imine and the small ethylene monomer is cis to the amine. [ABSTRACT FROM AUTHOR]

New α-aminoaldimines with the formula of Et2NCMe2CHNR (R = iPr, tBu, Ph) and their dichloro or diacetato complexes of Ni, Pd, Pt are prepared and structurally characterized. A nickel complex is in a distorted tetrahedral configuration, and the Pd and Pt complexes (4–6) are of square planar form. The α-aminoaldimines can chelate to the metal in a C2-unsymmetric bidentate motif through the hetero functionalities of amine and imine, which show comparable transinfluence. Square planar organometallic palladium derivatives bearing α-aminoaldimines, including Pd–methyl, Pd–acetyl, and Pd–(η2-acetylnorboryl) (7–10), are also synthesized. The latter two species are a result of CO-insertion into Pd–methyl complexes and ensuing norbornene-insertion, respectively. The geometrical isomerism is found in the transconfiguration in most studied cases. Such a stereoselectivity results from the thermodynamic stability governed predominantly by steric control. The stereoselectivity is also supported by DFT calculations. [ABSTRACT FROM AUTHOR]

A new ligand with N8O2 donors containing three potential metalbinding sites (H2L) and its tricopper(II) complex 1 are synthesized. The tricopper species is found to be formed from a hypodentate dicopper(II) complex 2 in basic solutions. Complex 2 may be isolated from the reaction of H2L with a copper source under acidic conditions. Complex 2 can undergo CO2-abstraction to yield an octacopper(II) complex 3. The single crystal structures of complexes 2 and 3 are characterized by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Introduction: The radiofrequency ablation (RFA) of liver cancer is a desirable treatment option, as it is minimally invasive. An accurate numerical simulation can greatly help physicians better plan their surgical protocols. Previously, the displacement current in the RFA process was considered negligible, and therefore RFA simulation was modeled as a direct current (DC) system instead of an alternating current (AC) system. Our study investigated the hypothesis that the displacement current in the RFA process should not always be considered negligible., Methods: AC measurements of ex vivo bovine liver ablation were performed, and numerical simulations were also conducted to test the hypothesis that the relative permittivity would significantly decrease after the liver tissue reached a high temperature., Results: The displacement current was observed to be a sizable fraction of the conduction current, especially before the onset of the first pause. The simulation results indicated that the relative permittivity is likely to decrease to several hundred or lower at elevated temperatures., Conclusions: Our study results suggest that the DC model may be inadequate, especially before the first roll-off and that additional information could be available during RFA treatment by considering the AC nature of RFA, which could lead to improved numerical simulation. Additional measurements of tissue parameters are needed to reach the full potential of the AC model for further development of ablation control.

RNAi is a highly conserved machinery in eukaryotes for transcriptional or post-transcriptional silencing. In plants, RNA-directed DNA Methylation (RdDM) pathway deploys small interfering RNAs (siRNAs) to target DNA methylation. This process is initiated by the plant-specific RNA polymerase IV (Pol IV) to produce RNA precursors that are later processed into siRNAs. Until recently, characterization of Pol IV transcript had been difficult due to its presumed rapid turnover. This review summarizes five recent reports on Pol IV-dependent RNAs that explore the biogenesis and features of Pol IV transcripts, as well as alternative dicer-independent processing of Pol IV products., (Copyright © 2016 Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and Genetics Society of China. Published by Elsevier Ltd. All rights reserved.)