bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion‐neutral coupling effects on low‐latitude thermospheric evening winds
Authors: Evonosky W. , Richmond A. D. , Fang T.‐W. , Maute A. 
Published: April 2016

AbstractWe examine the forces that determine zonal wind structure in the low‐latitude evening thermosphere and its relation with ion‐neutral coupling. These winds drive the evening F region dynamo that affects the equatorial ionization anomaly (EIA) and the generation of plasma irregularities. Forces are calculated using the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model coupled with the Global Ionosphere‐Plasmasphere model. At 19 LT, the horizontal pressure gradient dominates the net acceleration of neutral winds below ∼220 km, while it tends to be offset by ion drag and viscosity higher up. The eastward pressure‐gradient acceleration above 200 km increases approximately linearly with height and tends to be similar for different latitudes and different levels of solar activity. The pressure‐gradient and ion‐drag forces in the central F region approximately balance for field lines that pass through the EIA. Viscosity is an important additional force at non‐EIA latitudes and in the bottomside and topside EIA ionosphere. An increase in E region drag on plasma convection due to increased nighttime ionization causes both the ion and neutral velocities in the F region to decrease, while the velocity difference tends to be maintained. The presence of a low‐latitude evening time vertical shear in the zonal wind is associated primarily with a strong eastward pressure‐gradient acceleration at high altitude that reverses the daytime westward wind and a weak low‐altitude pressure‐gradient acceleration of either eastward or westward direction that fails to reverse the low‐altitude westward wind present in the afternoon.
Grey zone simulations of the morning convective boundary layer development
Authors: Efstathiou G. A. , Beare R. J. , Osborne S. , Lock A. P. 
Published: April 2016

AbstractNumerical simulations of two cases of morning boundary layer development are conducted to investigate the impact of grid resolution on mean profiles and turbulent kinetic energy (TKE) partitioning from the large eddy simulation (LES) to the mesoscale limit. Idealized LES, using the 3‐D Smagorinsky scheme, is shown to be capable of reproducing the boundary layer evolution when compared against measurements. However, increasing grid spacing results in the damping of resolved TKE and the production of superadiabatic temperature profiles in the boundary layer. Turbulence initiation is significantly delayed, exhibiting an abrupt onset at intermediate resolutions. Two approaches, the bounding of vertical diffusion coefficient and the blending of the 3‐D Smagorinsky with a nonlocal 1D scheme, are used to model subgrid diffusion at grey zone resolutions. Simulations are compared against the coarse‐grained fields from the validated LES results for each case. Both methods exhibit particular strengths and weaknesses, indicating the compromise that needs to be made currently in high‐resolution numerical weather prediction. The blending scheme is able to reproduce the adiabatic profiles although turbulence is underestimated in favor of the parametrized heat flux, and the spin‐up of TKE remains delayed. In contrast, the bounding approach gives an evolution of TKE that follows the coarse‐grained LES very well, relying on the resolved motions for the nonlocal heat flux. However, bounding gives unrealistic static instability in the early morning temperature profiles (similar to the 3‐D Smagorinsky scheme) because model dynamics are unable to resolve TKE when the boundary layer is too shallow compared to the grid spacing.
Thermal Responsive Ion Selectivity of Uranyl Peroxide Nanocages: An Inorganic Mimic of K+ Ion Channels
Authors: Gao Yunyi , Szymanowski Jennifer E. S. , Sun Xinyu , Burns Peter C. , Liu Tianbo 
Published: April 2016

AbstractAn actinyl peroxide cage cluster, Li48+mK12(OH)m[UO2(O2)(OH)]60 (H2O)n (m≈20 and n≈310; U60), discriminates precisely between Na+ and K+ ions when heated to certain temperatures, a most essential feature for K+ selective filters. The U60 clusters demonstrate several other features in common with K+ ion channels, including passive transport of K+ ions, a high flux rate, and the dehydration of U60 and K+ ions. These qualities make U60 (a pure inorganic cluster) a promising ion channel mimic in an aqueous environment. Laser light scattering (LLS) and isothermal titration calorimetry (ITC) studies revealed that the tailorable ion selectivity of U60 clusters is a result of the thermal responsiveness of the U60 hydration shells.
Nanorod Aspect Ratios Determined by the Nano‐Impact Technique
Authors: Plowman Blake J. , Young Neil P. , Batchelor‐McAuley Christopher , Compton Richard G. 
Published: April 2016

AbstractThe in situ electrochemical sizing of individual gold nanorods is reported. Through the combination of electrochemical dissolution and the use of a surface‐bound redox tag, the volume and surface area of the nanorods are measured, and provide the aspect ratio and the size of the nanorods. Excellent independent agreement is found with electron microscopy analysis of the nanorods, establishing the application of nano‐impact experiments for the sizing of anisotropic nanomaterials.
Unveiling the diversity of cyclotides by combining peptidome and transcriptome analysis
Authors: Koehbach Johannes , Clark Richard J. 
Published: April 2016

AbstractCircular peptides have attracted much interest in recent drug development efforts, particularly due to their increased stability over linear counterparts. The family of plant cyclotides represents one of the largest classes of naturally‐occurring backbone‐cyclized peptides displaying exceptional sequence variability and plasticity around three knotted disulfide bonds. Accordingly, a multitude of pharmaceutically as well as agrochemically relevant bioactivities has been ascribed to them. Their abundance across various species within flowering plants is highlighted by estimated numbers of up to 150,000 different sequences present in single plant families and over 160 at the species level. However, this vast diversity impedes thorough sequence characterization by standard analytical methods using mass spectrometry and thus limits access to a wealth of potentially bioactive compounds that may represent novel lead molecules. Recently the ribosomal origin of cyclotides has been exploited as an alternative way to discover novel sequences. The analysis at nucleotide level allows not only the identification of peptides but also their parent precursor proteins. This combined approach opens access to the discovery of sequences that can provide novel structural templates for a variety of pharmaceutical as well as agrochemical applications. Here we review recent literature related to the discovery of cyclotides. Challenges and opportunities using classical mass spectrometry workflows and novel approaches such as in silico mining will be discussed. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 774–783, 2016.
Polycationic ligands of different chemical classes stimulate DNA strand displacement between short oligonucleotides in a protein‐free system
Authors: Volodin Alexander A. , Bocharova Tatiana N. , Smirnova Elena A. 
Published: April 2016

ABSTRACTThe ability of polycationic ligands to stimulate DNA strand displacement between short oligonucleotides in a protein‐free system is demonstrated. We show that two ligands, tetracationic aliphatic amine (spermine) and a dicationic intercalating drug (chloroquine), promote strand displacement in a concentration‐dependent manner. At low concentrations both ligands decelerate spontaneous strand displacement because of their impact on the stability of the DNA duplex. At elevated concentrations they accelerate strand displacement via formation of intermediate structures containing three DNA strands. The rate of the last process does not correlate with the thermal dissociation rate of the entire DNA duplex. It indicates that, possibly, the action of these agents cannot be explained by their influence on the stability of the DNA duplex. In general, our results suggest that the ability to stimulate DNA strand displacement appears to be a common feature of polycations of different chemical and structural classes. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 633–641, 2016.
Residual determination and risk assessment of buprofezin in plum (Prunus domestica) grown in open‐field conditions following the application of three different formulations
Authors: Kabir Md. Humayun , Abd El‐Aty A.M. , Kim Sung‐Woo , Lee Han Sol , Rahman Md. Musfiqur , Lee Young‐Jun , Chung Hyung Suk , Lieu Truong , Choi Jeong‐Heui , Shin Ho‐Chul , Im Geon‐Jae , Hong Su Myeong , Shim Jae‐Han 
Published: April 2016

AbstractThis study was conducted to characterize the residual level and perform a risk assessment on buprofezin formulated as an emulsifiable concentrate, wettable powder, and suspension concentrate over various treatment schedules in plum (Prunus domestica). The samples were extracted with an AOAC quick, easy, cheap, effective, rugged, and safe, ‘QuEChERS’, method after major modifications. As intrinsic interferences were observed in blank plum samples following dispersive‐solid phase extraction (consisting of primary secondary amine and C18 sorbents), amino cartridges were used for solid‐phase extraction. Analysis was carried out using liquid chromatography with diode array detection and confirmed by liquid chromatography–tandem mass spectrometry. The method showed excellent linearity with determination coefficient (R2 = 1) and satisfactory recoveries (at two spiking levels, 0.5 and 2.5 mg/kg) between 90.98 and 94.74% with relative standard deviation (RSD) ≤8%. The limit of quantification (0.05 mg/kg) was considerably lower than the maximum residue limit (2 mg/kg) set by the Codex Alimentarius. Absolute residue levels for emulsifiable concentrates were highest, perhaps owing to the dilution rate and adjuvant. Notably, all formulation residues were lower than the maximum residue limit, and safety data proved that the fruits are safe for consumers. Copyright © 2016 John Wiley & Sons, Ltd.
A highly sensitive and efficient UPLC‐MS/MS assay for rapid analysis of tedizolid (a novel oxazolidinone antibiotic) in plasma sample
Authors: Iqbal Muzaffar 
Published: April 2016

AbstractTedizolid (TDZ) is a novel oxazolidinone class antibiotic, indicated for the treatment of acute bacterial skin and skin structure infections in adults. In this study a highly sensitive UPLC‐MS/MS assay was developed and validated for the determination of TDZ in rat plasma using rivaroxaban as an internal standard (IS). Both TDZ and IS were separated on an Acquity UPLC BEH™ C18 column using an isocratic mobile phase comprising of acetonitrile–20 mm ammonium acetate (85:15, v/v), eluted at 0.3 mL/min flow rate. The plasma sample was processed by liquid liquid extraction technique using ethyl acetate as an extracting agent. The analyte and IS were detected in positive mode using electrospray ionization source. The precursor to product ion transitions at m/z 371.09 > 343.10 for TDZ and m/z 435.97 > 144.94 for IS were used for the quantification in multiple reaction monitoring mode. The calibration curve was linear in the concentration range of 0.74–1500 ng/mL and the lower limit of quantification was 0.74 ng/mL only. The developed assay was validated following standard guidelines for bioanalytical method validation (US Food and Drug Administration) and all the validation results were within the acceptable limits. The developed assay was successfully applied into a pharmacokinetic study in rats. Copyright © 2016 John Wiley & Sons, Ltd.
Breast cancer screening disparities among immigrant women by world region of origin: a population‐based study in Ontario, Canada
Authors: Vahabi Mandana , Lofters Aisha , Kumar Matthew , Glazier Richard H. 
Published: April 2016

AbstractRates of mammography screening for breast cancer are disproportionately low in certain subgroups including low‐income and immigrant women. The purpose of the study was to examine differences in rates of appropriate breast cancer screening (i.e., screening mammography every 2 years) among Ontario immigrant women by world region of origin and explore the association between appropriate breast cancer screening among these women groups and individual and structural factors. A cohort of 183,332 screening‐eligible immigrant women living in Ontario between 2010 and 2012 was created from linked databases and classified into eight world regions of origin. Appropriate screening rates were calculated for each region by age group and selected sociodemographic, immigration, and healthcare‐related characteristics. The association between appropriate screening across the eight regions of origin and selected sociodemographic, immigration, and health‐related characteristics was explored using multivariate Poisson regression. Screening varied by region of origin, with South Asian women (48.5%) having the lowest and Caribbean and Latin American women (63.7%) the highest cancer screening rates. Factors significantly associated with lower screening across the world regions of origin included living in the lowest income neighborhoods, having a refugee status, being a new immigrant, not having a regular physical examination, not being enrolled in a primary care patient enrollment model, having a male physician, and having an internationally trained physician. Multiple interventions entailing cross‐sector collaboration, promotion of patient enrollment models, community engagement, comprehensive and intensive outreach to women, and knowledge translation and transfer to physicians should be considered to address screening disparities among immigrant population. Consideration should be given to design and delivery of culturally appropriate and easily accessible cancer screening programs targeted at high‐ risk immigrant subgroups, such as women of South Asian origin, refugees, and new immigrants.
High‐mobility group box‐B1 (HMGB1) mediates the hypoxia‐induced mesenchymal transition of osteoblast cells via activating ERK/JNK signaling
Authors: Qiu Yiyan , Chen Yang , Zeng Tenghui , Guo Weizhuang , Zhou Wenyu , Yang Xinjian 
Published: April 2016

AbstractHigh‐mobility group box 1 (HMGB1) is a nuclear protein that involves the binding with DNA and influences chromatin regulation and transcription. HMGB1 activates monocytes and neutrophils, which are involved in inflammation during wounding. In this study, we investigated the promotion of HMGB1 under hypoxia and determined the regulatory role of HMGB1 on the fibrosis of mouse osteoblast‐like MC3T3‐E1 cells or of human osteoblast MG‐63 cells. Results demonstrated that HMGB1 expression was significantly upregulated in MC3T3‐E1 or MG‐63 cells under hypoxia. We also found that treatment with 10 and 100 ng/mL of HMGB1 significantly promoted the fibrosis‐associated markers such as Collagen I, α‐SMA, whereas downregulated the E‐cadherin, indicating the differentiation of MC3T3‐E1 or MG‐63 cells into fibroblast cells. Further investigation indicated that the HMGB1 treatment markedly activated the mitogen‐activated protein kinases (MAPKs), including extracellular signal‐related kinase (ERK), c‐Jun N‐terminal kinase (JNK), and p38 mitogen‐activated protein kinase (p38) phosphorylation, as well as nuclear factor (NF)‐κB nuclear translocation. On the other side, using specific inhibitors and shRNAs of protein kinases, we observed that repression of ERK, JNK, p38, and NF‐κB all inhibited HMGB1‐induced cellular differentiation and migration of MC3T3‐E1 cells. In addition, knocking down of advanced glycation end products (RAGE) but not Toll‐like receptor (TLR)2 and TLR4 by shRNAs attenuated HMGB1‐induced myofibroblast differentiation and migration. In conclusion, our study demonstrated that HMGB1 induced the fibrosis of osteoblasts in vitro via activating the RAGE‐MAPK and NF‐κB interaction signaling pathways.
A Boron‐Fluorinated Tris(pyrazolyl)borate Ligand (FTp*) and Its Mono‐ and Dinuclear Copper Complexes [Cu(FTp*)2] and [Cu2(FTp*)2]: Synthesis, Structures, and DFT Calculations
Authors: Augenstein Timo , Dorner Franziska , Reiter Kevin , Wagner Hanna E. , Garnier Delphine , Klopper Wim , Breher Frank 
Published: April 2016

AbstractReaction of [Si(3,5‐Me2pz)4] (1) with [Cu(MeCN)4][BF4] (2) gave the mono‐ and dinuclear copper complexes [Cu2(FTp*)2] (3) and [Cu(FTp*)2] (4). Both complexes contain the so‐far unprecedented boron‐fluorinated FTp* ligand ([FB(3,5‐Me2pz)3]− with pz=pyrazolyl) originating from 1, acting as a pyrazolyl transfer reagent, and the [BF4]− counter anion of 2, serving as the source of the {BF} entity. The solid‐state structures as well as the NMR and EPR spectroscopic characteristics of the complexes were elaborated. Pulsed gradient spin echo (PGSE) experiments revealed that 3 retains (almost entirely) its dimeric structure in benzene, whereas dimer cleavage and formation of acetonitrile adducts, presumably [Cu(FTp*)(MeCN)], is observed in acetonitrile. The short Cu⋅⋅⋅Cu distance of 269.16 pm in the solid‐state is predicted by DFT calculations to be dictated by dispersion interactions between all atoms in the complex (the Cu−Cu dispersion contribution itself is only very small). As revealed by cyclic voltammetry studies, 3 shows an irreversible (almost quasi‐reversible at higher scan rates) oxidation process centred at Epa=−0.23 V (E01/2=−0.27 V) (vs. Fc/Fc+). Oxidation reactions on a preparative scale with one equivalent of the ferrocenium salt [Fc][BF4] (very slow reaction) or air (fast reaction) furnished blue crystals of the mononuclear copper(II) complex [Cu(FTp*)2] (4). As expected for a Jahn–Teller‐active system, the coordination sphere around copper(II) is strongly distorted towards a stretched octahedron, in accordance with EPR spectroscopic findings.
Mono‐ and Dinuclear Phosphorescent Rhenium(I) Complexes: Impact of Subcellular Localization on Anticancer Mechanisms
Authors: Ye Rui‐Rong , Tan Cai‐Ping , Chen Mu‐He , Hao Liang , Ji Liang‐Nian , Mao Zong‐Wan 
Published: April 2016

AbstractElucidation of relationship among chemical structure, cellular uptake, localization, and biological activity of anticancer metal complexes is important for the understanding of their mechanisms of action. Organometallic rhenium(I) tricarbonyl compounds have emerged as potential multifunctional anticancer drug candidates that can integrate therapeutic and imaging capabilities in a single molecule. Herein, two mononuclear phosphorescent rhenium(I) complexes (Re1 and Re2), along with their corresponding dinuclear complexes (Re3 and Re4), were designed and synthesized as potent anticancer agents. The subcellular accumulation of Re1–Re4 was conveniently analyzed by confocal microscopy in situ in live cells by utilizing their intrinsic phosphorescence. We found that increased lipophilicity of the bidentate ligands could enhance their cellular uptake, leading to improved anticancer efficacy. The dinuclear complexes were more potent than the mononuclear counterparts. The molecular anticancer mechanisms of action evoked by Re3 and Re4 were explored in detail. Re3 with a lower lipophilicity localizes to lysosomes and induces caspase‐independent apoptosis, whereas Re4 with higher lipophilicity specially accumulates in mitochondria and induces caspase‐independent paraptosis in cancer cells. Our study demonstrates that subcellular localization is crucial for the anticancer mechanisms of these phosphorescent rhenium(I) complexes.
Cationic Si−H−Si Bridges in Polysilanes: Their Detection and Targeted Formation in Stable Ion Studies
Authors: Albers Lena , Baumgartner Judith , Marschner Christoph , Müller Thomas 
Published: April 2016

AbstractThe ionization of 1,1‐dihydridocyclopentasilane 7 has been found to yield the cyclic polysilanylsilyl cation 8 instead of the expected hydrogen‐substituted silylium ion 6. The silyl cation 8 is stabilized by the formation of an intramolecular Si−H−Si bridge, which also provides the thermodynamic driving force for its formation. In general, the preference for the formation of Si−H−Si bridges can be used to scavenge and identify transient intermediates in the Lewis acid induced rearrangement of polysilanes. The validity of this concept has been demonstrated for one central step in this chemistry, the ring‐contraction reaction of cyclohexasilanes to form silylcyclopentasilanes.
Adsorption of Carbon Dioxide on Unsaturated Metal Sites in M2(dobpdc) Frameworks with Exceptional Structural Stability and Relation between Lewis Acidity and Adsorption Enthalpy
Authors: Yoo Ga Young , Lee Woo Ram , Jo Hyuna , Park Joonho , Song Jeong Hwa , Lim Kwang Soo , Moon Dohyun , Jung Hyun , Lim Juhyung , Han Sang Soo , Jung Yousung , Hong Chang Seop 
Published: April 2016

AbstractA series of metal–organic frameworks (MOFs) M2(dobpdc) (M=Mn, Co, Ni, Zn; H4dobpdc=4,4′‐dihydroxy‐1,1′‐biphenyl‐3,3′‐dicarboxylic acid), with a highly dense arrangement of open metal sites along hexagonal channels were prepared by microwave‐assisted or simple solvothermal reactions. The activated materials were structurally expanded when guest molecules including CO2 were introduced into the pores. The Lewis acidity of the open metal sites varied in the order Mn<Co<Ni>Zn, as confirmed by C=O stretching bands in the IR spectra, which are related to the CO2 adsorption enthalpy. DFT calculations revealed that the high CO2 binding affinity of transition‐metal‐based M2(dobpdc) is primarily attributable to the favorable charge transfer from CO2 (oxygen lone pair acting as a Lewis base) to the open metal sites (Lewis acid), while electrostatic effects, the underlying factor responsible for the particular order of binding strength observed across different transition metals, also play a role. The framework stability against water coincides with the order of Lewis acidity. In this series of MOFs, the structural stability of Ni2(dobpdc) is exceptional; it endured in water vapor, liquid water, and in refluxing water for one month, and the solid remained intact on exposure to solutions of pH 2–13. The DFT calculations also support the experimental finding that Ni2(dobpdc) has higher chemical stability than the other frameworks.
Direct Synthesis of Highly Substituted Pyrroles and Dihydropyrroles Using Linear Selective Hydroacylation Reactions
Authors: Majhail Manjeet K. , Ylioja Paul M. , Willis Michael C. 
Published: April 2016

AbstractRhodium(I) catalysts incorporating small bite‐angle diphosphine ligands, such as (Cy2P)2NMe or bis(diphenylphosphino)methane (dppm), are effective at catalysing the union of aldehydes and propargylic amines to deliver the linear hydroacylation adducts in good yields and with high selectivities. In situ treatment of the hydroacylation adducts with p‐TSA triggers a dehydrative cyclisation to provide the corresponding pyrroles. The use of allylic amines, in place of the propargylic substrates, delivers functionalised dihydropyrroles. The hydroacylation reactions can also be combined in a cascade process with a RhI‐catalysed Suzuki‐type coupling employing aryl boronic acids, providing a three‐component assembly of highly substituted pyrroles.