bluuebunny/crossref_metadata_2025 huggingface dataset:
Lidar remote sensing of cloud formation caused by low‐level jets
Authors: Su Jia , Felton Melvin , Lei Liqiao , McCormick M. Patrick , Delgado Ruben , St. Pé Alexandra
Published: April 2016

In May 2014, the East Hampton Roads Aerosol Flux campaign was conducted at Hampton University to examine small‐scale aerosol transport using aerosol, Raman, and Doppler lidars and rawindsonde launches. We present the results of analyses performed on these high‐resolution planetary boundary layer and lower atmospheric measurements, with a focus on the low‐level jets (LLJs) that form in this region during spring and summer. We present a detailed case study of a LLJ lasting from evening of 20 May to morning of 21 May using vertical profiles of aerosol backscatter, wind speed and direction, water vapor mixing ratio, temperature, and turbulence structure. We show with higher resolution than in previous studies that enhanced nighttime turbulence triggered by LLJs can cause the aerosol and water vapor content of the boundary layer to be transported vertically and form a well‐mixed region containing the cloud condensation nuclei that are necessary for cloud formation.
Hydrogen and chlorine abundances in the Kimberley formation of Gale crater measured by the DAN instrument on board the Mars Science Laboratory Curiosity rover
Authors: Litvak M. L. , Mitrofanov I. G. , Hardgrove C. , Stack K. M. , Sanin A. B. , Lisov D. , Boynton W. V. , Fedosov F. , Golovin D. , Harshman K. , Jun I. , Kozyrev A. S. , Kuzmin R. O. , Malakhov A. , Milliken R. , Mischna M. , Moersch J. , Mokrousov M. , Nikiforov S. , Starr R. , Tate C. , Tret'yakov V. I. , Vostrukhin A.
Published: April 2016

The Dynamic Albedo of Neutron (DAN) instrument on board the Mars Science Laboratory Curiosity rover acquired a series of measurements as part of an observational campaign of the Kimberley area in Gale crater. These observations were planned to assess the variability of bulk hydrogen and neutron‐absorbing elements, characterized as chlorine‐equivalent concentration, in the geologic members of the Kimberley formation and in surface materials exposed throughout the area. During the traverse of the Kimberley area, Curiosity drove primarily over the “Smooth Hummocky” unit, a unit composed primarily of sand and loose rocks, with occasional stops at bedrock of the Kimberley formation. During the Kimberley campaign, DAN detected ranges of water equivalent hydrogen (WEH) and chlorine‐equivalent concentrations of 1.5–2.5 wt % and 0.6–2 wt %, respectively. Results show that as the traverse progressed, DAN observed an overall decrease in both WEH and chlorine‐equivalent concentration measured over the sand and loose rocks of the Smooth Hummocky unit. DAN measurements of WEH and chlorine‐equivalent concentrations in the well‐exposed sedimentary bedrock of the Kimberley formation show fluctuations with stratigraphic position. The Kimberley campaign also provided an opportunity to compare measurements from DAN with those from the Sample Analysis at Mars (SAM) and the Alpha‐Particle X‐ray Spectrometer (APXS) instruments. DAN measurements obtained near the Windjana drill location show a WEH concentration of ~1.5 wt %, consistent with the concentration of low‐temperature absorbed water measured by SAM for the Windjana drill sample. A comparison between DAN chlorine‐equivalent concentrations measured throughout the Kimberley area and APXS observations of corresponding local surface targets and drill fines shows general agreement between the two instruments.
A dense medium electromagnetic scattering model for the InSAR correlation of snow
Authors: Lei Yang , Siqueira Paul , Treuhaft Robert
Published: April 2016

Snow characteristics, such as snow water equivalent (SWE) and snow grain size, are important characteristics for the monitoring of the global hydrological cycle and as indicators of climate change. This paper derives an interferometric synthetic aperture radar (InSAR) scattering model for dense media, such as snow, which takes into account multiple scattering effects through the Quasi‐Crystalline Approximation. The result of this derivation is a simplified version of the InSAR correlation model derived for relating the InSAR correlation measurements to the snowpack characteristics of grain size, volume fraction, and layer depth as well as those aspects of the volume‐ground interaction that affects the interferometric observation (i.e., the surface topography and the ratio of ground‐to‐volume scattering). Based on the model, the sensitivity of the InSAR correlation measurements to the snow characteristics is explored by simulation. Through this process, it is shown that Ka‐band InSAR phase has a good sensitivity to snow grain size and volume fraction, while for lower frequency signals (Ku‐band to L‐band), the InSAR correlation magnitude and phase have a sensitivity to snow depth. Since the formulation depends, in part, on the pair distribution function, three functional forms of the pair distribution function are implemented and their effects on InSAR phase measurements compared. The InSAR scattering model described in this paper is intended to be an observational prototype for future Ka‐band and L‐band InSAR missions, such as NASA's Surface Water and Ocean Topography and NASA‐ISRO Synthetic Aperture Radar missions, planned for launch in the 2020–2021 time frame. This formulation also enables further investigation of the InSAR‐based snow retrieval approaches.
A new view for the geodynamics of Ecuador: Implication in seismogenic source definition and seismic hazard assessment
Authors: Yepes Hugo , Audin Laurence , Alvarado Alexandra , Beauval Céline , Aguilar Jorge , Font Yvonne , Cotton Fabrice
Published: April 2016

A new view of Ecuador's complex geodynamics has been developed in the course of modeling seismic source zones for probabilistic seismic hazard analysis. This study focuses on two aspects of the plates' interaction at a continental scale: (a) age‐related differences in rheology between Farallon and Nazca plates—marked by the Grijalva rifted margin and its inland projection—as they subduct underneath central Ecuador, and (b) the rapidly changing convergence obliquity resulting from the convex shape of the South American northwestern continental margin. Both conditions satisfactorily explain several characteristics of the observed seismicity and of the interseismic coupling. Intermediate‐depth seismicity reveals a severe flexure in the Farallon slab as it dips and contorts at depth, originating the El Puyo seismic cluster. The two slabs position and geometry below continental Ecuador also correlate with surface expressions observable in the local and regional geology and tectonics. The interseismic coupling is weak and shallow south of the Grijalva rifted margin and increases northward, with a heterogeneous pattern locally associated to the Carnegie ridge subduction. High convergence obliquity is responsible for the North Andean Block northeastward movement along localized fault systems. The Cosanga and Pallatanga fault segments of the North Andean Block‐South American boundary concentrate most of the seismic moment release in continental Ecuador. Other inner block faults located along the western border of the inter‐Andean Depression also show a high rate of moderate‐size earthquake production. Finally, a total of 19 seismic source zones were modeled in accordance with the proposed geodynamic and neotectonic scheme.
Large‐scale variation in boreal and temperate forest carbon turnover rate related to climate
Authors: Thurner Martin , Beer Christian , Carvalhais Nuno , Forkel Matthias , Santoro Maurizio , Tum Markus , Schmullius Christiane
Published: April 2016

Vegetation carbon turnover processes in forest ecosystems and their dominant drivers are far from being understood at a broader scale. Many of these turnover processes act on long timescales and include a lateral dimension and thus can hardly be investigated by plot‐level studies alone. Making use of remote sensing‐based products of net primary production (NPP) and biomass, here we show that spatial gradients of carbon turnover rate (k) in Northern Hemisphere boreal and temperate forests are explained by different climate‐related processes depending on the ecosystem. k is related to frost damage effects and the trade‐off between growth and frost adaptation in boreal forests, while drought stress and climate effects on insects and pathogens can explain an elevated k in temperate forests. By identifying relevant processes underlying broadscale patterns in k, we provide the basis for a detailed exploration of these mechanisms in field studies, and ultimately the improvement of their representations in global vegetation models (GVMs).
On the temperature dependence of oceanic export efficiency
Authors: Cael B. B. , Follows Michael J.
Published: April 2016

Quantifying the fraction of primary production exported from the euphotic layer (termed the export efficiency ef) is a complicated matter. Studies have suggested empirical relationships with temperature which offer attractive potential for parameterization. Here we develop what is arguably the simplest mechanistic model relating the two, using established thermodynamic dependencies for primary production and respiration. It results in a single‐parameter curve that constrains the envelope of possible efficiencies, capturing the upper bounds of several ef‐T data sets. The approach provides a useful theoretical constraint on this relationship and extracts the variability in ef due to temperature but does not idealize out the remaining variability which evinces the substantial complexity of the system in question.
Ion‐neutral coupling effects on low‐latitude thermospheric evening winds
Authors: Evonosky W. , Richmond A. D. , Fang T.‐W. , Maute A.
Published: April 2016

We 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

Numerical 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.
Polyphosphate as a Bioactive and Biodegradable Implant Material: Induction of Bone Regeneration in Rats
Authors: Wang Xiaohong , Wang Shunfeng , He Feng , Tolba Emad , Schröder Heinz C. , Diehl‐Seifert Bärbel , Müller Werner E. G.
Published: April 2016

Inorganic polyphosphate (polyP) is a naturally occurring polymer that is bioresorbable and anabolically active on bone forming cells in vitro. In order to demonstrate if polyP also shows morphogenetic activity in vivo, animal studies are performed applying the rat calvarial defect model. Poly(D,L‐lactide‐co‐glycolide) (PLGA) microspheres with a narrow size distribution (≈820 μm) are prepared, containing either encapsulated polyP or β‐tricalcium phosphate (β‐TCP), used as a reference material. Discs are prepared from the microspheres and inserted into 10 mm large defects created in the calvaria of rats. Both the formation of COL‐I and the expression of ALP is upregulated, as well as the extent of mineralization within and around the polyP implant. Our data demonstrate that amorphous and resorbable inorganic polyP is also morphogenetically active in vivo.
Anion‐Selective Redox Electrodes: Electrochemically Mediated Separation with Heterogeneous Organometallic Interfaces
Authors: Su Xiao , Kulik Heather J. , Jamison Timothy F. , Hatton T. Alan
Published: April 2016

Redox species have been explored extensively for catalysis, energy storage, and molecular recognition. It is shown that nanostructured pseudocapacitive electrodes functionalized with ferrocene‐based redox polymers are an attractive platform for the selective sorptive separation of dilute organic anions from strong aqueous and organic electrolyte solutions, and subsequent release of the sorbed ions to a stripping phase through electrochemical control of the specific binding processes. A remarkable degree of selectivity is shown for carboxylates (–COO–), sulfonates (–SO3−), and phosphonates (–PO3−2) over inorganic anions such as PF6− and ClO4− (separation factor >140 in aqueous and >3000 in organic systems), and between carboxylates with various substituents, based on differences in electronic structure and density of the adsorbates, beyond size, and charge. Our organometallic redox electrodes are a promising platform for targeting aqueous and organic systems requiring high separation factors and fast throughput, such as in the recovery of value‐added products from organic synthesis and isolation of dilute yet highly toxic organic contaminants. The combination of spectroscopic experiments and quantum chemistry sheds light on a selective binding mechanism based on redox‐enhanced hydrogen bonding between the cyclopentadienyl ligand and the carboxylate functional group, with broader implications for molecular design, supramolecular recognition, and metallocene catalysis.
Chitosan–Alginate Microcapsules Provide Gastric Protection and Intestinal Release of ICAM‐1‐Targeting Nanocarriers, Enabling GI Targeting In Vivo
Authors: Ghaffarian Rasa , Pérez‐Herrero Edgar , Oh Hyuntaek , Raghavan Srinivasa R. , Muro Silvia
Published: April 2016

When administered intravenously, active targeting of drug nanocarriers (NCs) improves biodistribution and endocytosis. Targeting may also improve NC oral delivery to treat gastrointestinal (GI) pathologies or for systemic absorption. However, GI instability of targeting moieties compromises this strategy. This study explores whether encapsulation of antibody‐coated NCs in microcapsules would protect against gastric degradation, providing NC release and targeting in intestinal conditions. Nanoparticles coated with antibodies against intercellular adhesion molecule‐1 (anti‐ICAM) or nonspecific immunoglobulin G (IgG) are encapsulated in chitosan (shell) ‐ alginate (core) microcapsules. Encapsulation efficiency is >95% and NC relase from microcapsules in storage is <10%. There is minimal NC release at gastric pH (<10%) and burst release at intestinal pH (75%–85%). Encapsulated NCs afford increased protection against degradation (threefold to fourfold) and increased cell targeting (8–20‐fold) after release versus the nonencapsulated NCs. Mouse oral gavage shows that microencapsulation provides 38%–65% greater protection of anti‐ICAM NCs in the GI tract, 40% lower gastric retention, and fourfold to ninefold enhanced intestinal biodistribution versus nonencapsulated NCs. Therefore, microencapsulation of antibody‐targeted NCs may enable active targeting strategies to be effective in the context of oral drug delivery.
Preparation of MnCo2O4@Ni(OH)2 Core–Shell Flowers for Asymmetric Supercapacitor Materials with Ultrahigh Specific Capacitance
Authors: Zhao Yan , Hu Linfeng , Zhao Shuyan , Wu Limin
Published: April 2016

Supercapacitors have attracted much interest in the past decades owing to their important applications, but most of them are focused on solitary or simple metal oxides. Here, a novel supercapacitor electrode composed of multicomponent MnCo2O4@Ni(OH)2 belt‐based core–shell nanoflowers is reported by a facile and cost‐effective method. This hybrid electrode exhibits a significantly enhanced specific capacitance. An asymmetric supercapacitor based on this unique hybrid nanoflowers as anode and an activated carbon film as cathode demonstrates high energy density, high power density, and long cycling lifespan.
Bipolar Electrochemical Synthesis of WS2 Nanoparticles and Their Application in Magneto‐Immunosandwich Assay
Authors: Mayorga‐Martinez Carmen C. , Khezri Bahareh , Eng Alex Yong Sheng , Sofer Zdeněk , Ulbrich Pavel , Pumera Martin
Published: April 2016

WS2 nanoparticles are prepared using bipolar electrochemistry. Obtained material exhibits high activity for hydrogen evolution reaction (HER) and it is used as a label in standard magneto‐immunosandwich assay for protein detection through HER. This new system shows high analytical performance in terms of a wide range, selectivity, sensitivity, and reproducibility.
Biomedical Uses for 2D Materials Beyond Graphene: Current Advances and Challenges Ahead
Authors: Kurapati Rajendra , Kostarelos Kostas , Prato Maurizio , Bianco Alberto
Published: April 2016

Currently, a broad interdisciplinary research effort is pursued on biomedical applications of 2D materials (2DMs) beyond graphene, due to their unique physicochemical and electronic properties. The discovery of new 2DMs is driven by the diverse chemical compositions and tuneable characteristics offered. Researchers are increasingly attracted to exploit those as drug delivery systems, highly efficient photothermal modalities, multimodal therapeutics with non‐invasive diagnostic capabilities, biosensing, and tissue engineering. A crucial limitation of some of the 2DMs is their moderate colloidal stability in aqueous media. In addition, the lack of suitable functionalisation strategies should encourage the exploration of novel chemical methodologies with that purpose. Moreover, the clinical translation of these emerging materials will require undertaking of fundamental research on biocompatibility, toxicology and biopersistence in the living body as well as in the environment. Here, a thorough account of the biomedical applications using 2DMs explored today is given.
A Versatile Dual‐Emission Fluorescent Microhybrid Enabling Visual Detection of Glucose and Other Oxidases‐Based Biocatalytic Systems
Authors: Lu Xiaohui , Wang Peipei , Wang Yucong , Liu Chenghui , Li Zhengping
Published: April 2016

A novel kind of dual‐emission microhybrids (DEMBs) is rationally fabricated which allows facile visual detection of glucose in serum. Here, green‐emitting rhodamine‐embedded silica microbeads (MBs) are used as the core of the DEMBs while a shell of CdTe quantum dots of red fluorescence is attached on the surface of MBs as the signal report unit. The red fluorescence of CdTe is susceptible to H2O2 produced by the glucose/glucose oxidase (GOD) reaction while the inner green fluorescence of the MBs is inert. Therefore, with the assistance of GOD, increased glucose levels can lead to variations of the two fluorescence intensity ratios of DEMBs accompanied with continuous color changes from red to green under a UV lamp, which can be easily and distinctly identified by naked eye. This DEMB‐based sensing strategy can be directly used for assaying glucose in serum and the results agree well with those measured by commercial glucose meter, indicating that this glucose sensing system is reliable for practical applications. More importantly, since many oxidases‐based enzymatic reactions can all produce H2O2, the proposed design may serve as a generic platform for probing of H2O2‐generating oxidases as well as their substrates.
A Safer Sodium‐Ion Battery Based on Nonflammable Organic Phosphate Electrolyte
Authors: Zeng Ziqi , Jiang Xiaoyu , Li Ran , Yuan Dingding , Ai Xinping , Yang Hanxi , Cao Yuliang
Published: April 2016

Sodium‐ion batteries are now considered as a low‐cost alternative to lithium‐ion technologies for large‐scale energy storage applications; however, their safety is still a matter of great concern for practical applications. In this paper, a safer sodium‐ion battery is proposed by introducing a nonflammable phosphate electrolyte (trimethyl phosphate, TMP) coupled with NaNi0.35Mn0.35Fe0.3O2 cathode and Sb‐based alloy anode. The physical and electrochemical compatibilities of the TMP electrolyte are investigated by igniting, ionic conductivity, cyclic voltammetry, and charge–discharge measurements. The results exhibit that the TMP electrolyte with FEC additive is completely nonflammable and has wide electrochemical window (0–4.5 V vs. Na/Na+), in which both the Sb‐based anode and NaNi0.35Mn0.35Fe0.3O2 cathode show high reversible capacity and cycling stability, similarly as in carbonate electrolyte. Based on these results, a nonflammable sodium‐ion battery is constructed by use of Sb anode, NaNi0.35Mn0.35Fe0.3O2 cathode, and TMP + 10 vol% FEC electrolyte, which works very well with considerable capacity and cyclability, demonstrating a promising prospect to build safer sodium‐ion batteries for large‐scale energy storage applications.
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

An 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

The 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

Circular 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

The 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

This 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

Tedizolid (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

Rates 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

High‐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

Reaction 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

Elucidation 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

The 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

A 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<CoZn, 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

Rhodium(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.
DFT Rationalization of the Diverse Outcomes of the Iodine(III)‐Mediated Oxidative Amination of Alkenes
Authors: Funes‐Ardoiz Ignacio , Sameera W. M. C. , Romero R. Martín , Martínez Claudio , Souto José A. , Sampedro Diego , Muñiz Kilian , Maseras Feliu
Published: April 2016

A computational study of the mechanism for the iodine(III)‐mediated oxidative amination of alkenes explains the experimentally observed substrate dependence on product distribution. Calculations with the M06 functional have been carried out on the reaction between PhI(N(SO2Me)2)2 and three different representative substrates: styrene, α‐methylstyrene, and (E)‐methylstilbene. All reactions start with electrophilic attack by a cationic PhI(N(SO2Me)2)+ unit on the double bond, and formation of an intermediate with a single C−I bond and a planar sp2 carbocationic center. The major path, leading to 1,2‐diamination, proceeds through a mechanism in which the bissulfonimide initially adds to the alkene through an oxygen atom of one sulfonyl group. This behavior is now corroborated by experimental evidence. An alternative path, leading to an allylic amination product, takes place through deprotonation at an allylic C−H position in the common intermediate. The regioselectivity of this amination depends on the availability of the resonant structures of an alternate carbocationic intermediate. Only in cases where a high electronic delocalization is possible, as in (E)‐methylstilbene, does the allylic amination occur without migration of the double bond.
Aggregation‐Induced Emission of Platinum(II) Metallacycles and Their Ability to Detect Nitroaromatics
Authors: Chowdhury Aniket , Howlader Prodip , Mukherjee Partha Sarathi
Published: April 2016

Two new acceptors containing platinum–carbazole (1) and platinum–triphenylamine (2) backbones with bite angles of 90° and 120°, respectively, have been synthesised and characterised. Reactions of the rigid acceptor 1 with linear dipyridyl‐based donors (3 and 4) generated [4+4] self‐assembled molecular squares (5 and 6), and similar treatments with acceptor 2 instead of 1 yielded [6+6] self‐assembled molecular hexagons (7 and 8). The metallacycles were characterised by multinuclear NMR spectroscopy (1H and 31P) and ESI‐MS. The geometries of the metallacycles were optimised by using the PM6 method. When aggregates of the metallacycles were formed by adding hexane solutions in dichloromethane, aggregation‐induced emission was observed for metallacycles 5 and 7, and aggregation‐caused quenching was observed for metallacycles 6 and 8. The formation of aggregates was verified by dynamic light scattering and TEM analyses. Macrocycles 5 and 7 are white‐light emitters in THF. Moreover, their high luminescence in both solution and the solid state was utilised for the recognition of nitroaromatic explosives.
Direct Observation of Carbamoylnitrenes
Authors: Li Hongmin , Wan Huabin , Wu Zhuang , Li Dingqing , Bégué Didier , Wentrup Curt , Zeng Xiaoqing
Published: April 2016

As the prototype Curtius rearrangement reaction, carbamoyl azide decomposes into aminoisocyanate and molecular nitrogen. However, the key intermediate carbamoylnitrene was previously undetected, even though the decomposition of carbamoyl azides has been studied frequently since its discovery in the 1890s. Upon ArF laser (λ=193 nm) photolysis, the stepwise decomposition of the two simplest carbamoyl azides H2NC(O)N3 and Me2NC(O)N3, isolated in solid noble gas matrices, occurs with the formation of the corresponding carbamoylnitrenes H2NC(O)N and Me2NC(O)N. Both triplet species are characterized for the first time by combining matrix‐isolation IR spectroscopy and quantum‐chemical calculations. Subsequent visible‐light irradiations cause efficient rearrangement of these nitrenes into the respective aminoisocyanates.
Total Synthesis and Complete Stereostructure of a Marine Macrolide Glycoside, (−)‐Lyngbyaloside B
Authors: Fuwa Haruhiko , Yamagata Naoya , Okuaki Yuta , Ogata Yuya , Saito Asami , Sasaki Makoto
Published: April 2016

Invited for the cover of this issue is the group of Haruhiko Fuwa at Tohoku University. The image depicts a puzzle of lyngbyaloside B, a complex macrolide natural product. Read the full text of the article at 10.1002/chem.201600341.
ChemInform Abstract: VERY SMALL BIMETALLIC CLUSTERS OF SILVER WITH MANGANESE, MOLYBDENUM, AND COPPER IN RARE GAS MATRIXES
Authors: KLOTZBUECHER W. E. + , OZIN G. A.
Published: April 2016

Gemeinsame Abscheidung von Ag‐Dampf mit Mn‐, Mooder Cu‐Dampf in Ar‐Matrices bei 10‐ 1 2 K eröffnet einen Syntheseweg zu niederkernigen, bimetallischen Clustem, von denen einige im entsprechenden Legierungssystem nur geringe Mischbarkeit aufweisen.
ChemInform Abstract: CRYSTAL STRUCTURE OF EUROPIUM(II) BROMOBORATE
Authors: MACHIDA K.‐I. , ADACHI G.‐Y. , YASUOKA N. , KASAI N. , SHIOKAWA J.
Published: April 2016

Das aus EuB2O4/B2O3/EuBr2‐Ge‐ mengen mit großem EuBrz‐Überschuß (als Flußmittel) durch Aufschmelzen bei ca. 1100°C dargestellte Eu2B5O9Br ist isostrukturell mit dem Ca‐Analogen (Pnn2, Z=4).
ChemInform Abstract: OXIDATION‐REDUCTION IN THE MIXED CALIFORNIUM, BERKELIUM OXIDE SYSTEM
Authors: TURCOTTE R. P.
Published: April 2016

Das Redox‐Verhalten von Cf wird an 2 Mischkristallen (Cf ,Bk)Ox unterschiedlicher Zusammensetzung untersucht.