bluuebunny/crossref_metadata_2025 huggingface dataset:
A new type of magnetic molecular imprinted material combined with β-cyclodextrin for the selective adsorption of zearalenone
Authors: Fu Han , Liu Junping , Xu Wu , Wang Haixiang , Liao Shenghua , Chen Guitang
Published: October 2020

In this paper, a new magnetic molecular imprinted polymer–cyclodextrin (MMIP–CD) material was prepared by connecting β-cyclodextrin (CD) on the surface of a magnetic molecular imprinted polymer (MMIP) and used for the rapid and specific adsorption of zearalenone (ZEN).
The LOFAR Two-meter Sky Survey: Deep Fields Data Release 1
Authors: Duncan K. J. , Kondapally R. , Brown M. J. I. , Bonato M. , Best P. N. , Röttgering H. J. A. , Bondi M. , Bowler R. A. A. , Cochrane R. K. , Gürkan G. , Hardcastle M. J. , Jarvis M. J. , Kunert-Bajraszewska M. , Leslie S. K. , Małek K. , Morabito L. K. , O’Sullivan S. P. , Prandoni I. , Sabater J. , Shimwell T. W. , Smith D. J. B. , Wang L. , Wołowska A. , Tasse C.
Published: October 2020

The Low Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS) is a sensitive, high-resolution 120-168 MHz survey split across multiple tiers over the northern sky. The first LoTSS Deep Fields data release consists of deep radio continuum imaging at 150 MHz of the Boötes, European Large Area Infrared Space Observatory Survey-North 1, and Lockman Hole fields, down to rms sensitivities of ~32, 20, and 22 μJy beam−1, respectively. In this paper we present consistent photometric redshift (photo-z) estimates for the optical source catalogues in all three fields – totalling over 7 million sources (~5 million after limiting to regions with the best photometric coverage). Our photo-z estimation uses a hybrid methodology that combines template fitting and machine learning and is optimised to produce the best possible performance for the radio continuum selected sources and the wider optical source population. Comparing our results with spectroscopic redshift samples, we find a robust scatter ranging from 1.6 to 2% for galaxies and 6.4 to 7% for identified optical, infrared, or X-ray selected active galactic nuclei. Our estimated outlier fractions (|zphot−zspec|/(1+zspec)>0.15) for the corresponding subsets range from 1.5 to 1.8% and 18 to 22%, respectively. Replicating trends seen in analyses of previous wide-area radio surveys, we find no strong trend in photo-z quality as a function of radio luminosity for a fixed redshift. We exploit the broad wavelength coverage available within each field to produce galaxy stellar mass estimates for all optical sources at z < 1.5. Stellar mass functions derived for each field are used to validate our mass estimates, with the resulting estimates in good agreement between each field and with published results from the literature.
Bolometric night sky temperature and subcooling of telescope structures
Authors: Holzlöhner R. , Kimeswenger S. , Kausch W. , Noll S.
Published: October 2020

Context.The termsky temperatureis used in the literature to refer to different phenomena in different contexts which often leads to confusion. In this work, we studyTsky, the effective bolometric sky temperature at which a hemispherical black body would radiate the same power onto a flat horizontal structure on the ground as the night sky, integrated over the entire thermal wavelength range of 1–100μm. We then analyze the thermal physics of radiative cooling with special focus on telescopes and discuss mitigation strategies.

Aims.The quantityTskyis useful to quantify the subcooling in telescopes which can deteriorate the image quality by introducing an optical path difference (OPD) and induce thermal stress and mechanical deflections on structures.

Methods.We employ the Cerro Paranal Sky Model of the European Southern Observatory to derive a simple formula ofTskyas a function of atmospheric parameters. The structural subcooling and the induced OPD are then expressed as a function of surface emissivity, sky view factor, local air speed, and structure dimensions.

Results.At Cerro Paranal (2600m) and Cerro Armazones (3060m) in the Atacama desert,Tskytowards the zenith mostly lies 25–50 Kelvin below the ambient temperature near the ground, depending to a great extent on the precipitable water vapor column in the atmosphere. The temperature difference can decrease by several Kelvin for higher zenith distances. The subcooling OPD scales linearly to quadratically with the telescope diameter and is inversely proportional to the local air speed near the telescope structure.
Hierarchical star formation in nearby galaxies
Authors: Rodríguez M. J. , Baume G. , Feinstein C.
Published: October 2020

Aims. The purpose of this work is to study the properties of the spatial distribution of the young population in three nearby galaxies in order to better understand the first stages of star formation.

Methods. We used ACS/HST photometry and the “path-linkage criterion” in order to obtain a catalog of young stellar groups (YSGs) in the galaxy NGC 2403. We studied the internal distribution of stars in these YSGs using the Q parameter. We extended these analyses to the YSGs detected in in NGC 300 and NGC 253 our previous works. We built the young stars’ density maps for these three galaxies. Through these maps, we were able to identify and study young stellar structures on larger scales.

Results. We found 573 YSGs in the galaxy NGC 2403, for which we derived their individual sizes, densities, luminosity function, and other fundamental characteristics. We find that the vast majority of the YSGs in NGC 2403, NGC 300 and NGC 253 present inner clumpings, following the same hierarchical behavior that we observed in the young stellar structures on larger scales in these galaxies. We derived values of the fractal dimension for these structures between ∼1.5 and 1.6. These values are very similar to those obtained in other star forming galaxies and in the interstellar medium, suggesting that the star formation process is regulated by supersonic turbulence.
The COld STream finder Algorithm (COSTA)
Authors: Gatto M. , Napolitano N. R. , Spiniello C. , Longo G. , Paolillo M.
Published: October 2020

Context. We present the COld STream finder Algorithm (COSTA), a novel algorithm used to search for cold kinematical substructures in the phase space of planetary nebulae (PNe) and globular clusters (GCs) in the halos of massive galaxies and intracluster regions.

Aims. The aim of COSTA is to detect small, low-velocity-dispersion streams, such as the ones produced in recent interactions of dwarf galaxies with the halos of more massive galaxies, including the ones sitting in the central regions of rich galaxy clusters.

Methods. We based COSTA on a deep friend-of-friend procedure that isolates groups of N particles with low velocity dispersion (between 10 km s−1 and ∼100 km s−1) using an iterative (n) sigma-clipping on a defined number of (k) neighbor particles. The algorithm has three parameters (k − n − N), plus a velocity dispersion cut-off that defines the “coldness” of the stream, which are set using Monte Carlo realizations of the sample in question.

Results. In this paper, we show the ability of COSTA to recover simulated streams on mock datasets of discrete kinematical tracers of different sizes and measurement errors, from publicly available hydrodynamical simulations. We also show the best algorithm setup for realistically locating streams in the core of the Fornax cluster, for future applications of COSTA to real populations of PNe and GCs.

Conclusions. Finally, COSTA can be adapted to many situations in finding small substructures in the phase space of a limited sample of discrete tracers, provided that the algorithm is trained on realistic mock observations reproducing the specific dataset under examination.
Impulsive coronal heating during the interaction of surface magnetic fields in the lower solar atmosphere
Authors: Chitta L. P. , Peter H. , Priest E. R. , Solanki S. K.
Published: October 2020

Coronal plasma in the cores of solar active regions is impulsively heated to more than 5 MK. The nature and location of the magnetic energy source responsible for such impulsive heating is poorly understood. Using observations of seven active regions from the Solar Dynamics Observatory, we found that a majority of coronal loops hosting hot plasma have at least one footpoint rooted in regions of interacting mixed magnetic polarity at the solar surface. In cases when co-temporal observations from the Interface Region Imaging Spectrograph space mission are available, we found spectroscopic evidence for magnetic reconnection at the base of the hot coronal loops. Our analysis suggests that interactions of magnetic patches of opposite polarity at the solar surface and the associated energy release during reconnection are key to impulsive coronal heating.
Concise Total Synthesis of Curvulone B
Authors: Mohapatra Debendra K. , Banoth Shivalal , Choudhury Utkal Mani , Marumudi Kanakaraju , Kunwar Ajit C.
Published: October 2020

A concise and convergent stereoselective synthesis of curvulone B is described. The synthesis utilized a tandem isomerization followed by C–O and C–C bond-forming reactions following Mukaiyama-type aldol conditions for the construction of the trans-2,6-disubstituted dihydropyran ring system as the key steps. Other important features of this synthesis are a cross-metathesis, epimerization, and Friedel–Crafts acylation.
Diazocarbonyl Compounds in Organofluorine Chemistry
Authors: Szabó Kálmán J. , Lübcke Marvin
Published: October 2020

Diazocarbonyl compounds are useful substrates in di- and trifunctionalization reactions based on F/CF3/SCF3 introduction. In the presented reactions, various electrophilic F/CF3/SCF3-transfer reagents were used. The majority of the reactions were based on rhodium catalysis and the application of various oxygen nucleophiles, such as alcohols, cyclic/acyclic ethers, and carboxylic acids. The oxyfluorination reactions were further developed to provide a new fluorine-18 labeling method. Density functional theory (DFT) modeling studies were performed to get a deeper mechanistic understanding of these reactions. These DFT modeling studies indicated that the catalytic reactions proceed through formation of rhodium carbene and oxonium ylide intermediates. The oxonium ylides undergo tautomerization to enol ether type species that subsequently react with the electrophilic F/CF3/SCF3-transfer reagents. We
also present an arylation–trifluoromethylthiolation reaction for simultaneous introduction of C–SCF3 and C–C bonds into diazocarbonyl compounds. This reaction does not proceed by rhodium catalysis, but follows a Hooz-type mechanism.

1 Introduction

2 Diazocarbonyl Compounds: Versatile Substrates in Organic ­Synthesis

3 Fluorination, Trifluoromethylation, and Trifluoromethylthiolation of Diazo Substrates

3.1 Metal-Free Reactions

3.2 Metal-Catalyzed Reactions with Nucleophilic Reagents

3.3 Metal-Catalyzed Reactions with Electrophilic Reagents

4 Oxyfluorination Reactions

4.1 Fluorobenziodoxole as a Fluorine Source

4.2 [18F]Fluorobenziodoxole as a Fluorine Source for Radiolabeling

4.3 Oxyfluorination with NFSI

5 Oxytrifluoromethylation

6 Oxytrifluoromethylthiolation

7 Arylation–Trifluoromethylthiolation Reaction

8 Conclusions and Outlook
Lower Urinary Pathogens: Do More Pathogenic Bacteria Increase the Risk of Pyelonephritis?
Authors: Rosett Heather A. , Krischak Madison K. , Sachdeva Sarika , Weaver Kristin E. , Heine Robert Phillips , Denoble Anna E. , Dotters-Katz Sarah K.
Published: October 2020

Objective Outside of pregnancy, urinary pathogens such as Proteus and Klebsiella are considered more pathogenic than E. coli. During pregnancy, the implications of lower urinary tract infection (LUTI) with more pathogenic bacteria are unclear. Thus, we sought to compare the risk of progression from LUTI to pyelonephritis among women infected with these more pathogenic urinary bacteria to those infected with E. coli.

Study Design Retrospective cohort of pregnant women with LUTI at single tertiary center from July 2013 to May 2019. Pathogenic infections (PI) were defined as asymptomatic bacteriuria or acute cystitis urinary cultures positive for Proteus, Klebsiella, Enterobacter, Citrobacter, Acinetobacter, Staphylococcus, or Raoultella species. Demographic, infectious, antepartum, and postpartum data abstracted. Pregnant women with PI compared with those with E. coli. Primary outcome was progression to pyelonephritis. Secondary outcomes included pyelonephritis length of stay (LOS) >6 days, preterm birth (PTB), low birthweight (LBW), and measures of pyelonephritis-related morbidity.

Results Of 686 pregnant women with LUTIs, 313 had urine culture growing out either PI or E. coli, with 59 (12%) growing PI and 254 (54%) growing E. coli. Women with PI were more likely to be African American, have chronic hypertension, and have history of preeclampsia. The primary species causing PI were Klebsiella (n = 29) and Proteus (n = 11). PI were not more likely to progress to pyelonephritis than E. coli LUTIs (10.9 vs. 14.5%; p = 0.67). Median LOS for pyelonephritis and other measures of pyelonephritis-related morbidity did not differ nor did PTB or LBW rates. After controlling for race, body mass index, history of preeclampsia, and history of pyelonephritis, PI were not associated with increased odds of progression to pyelonephritis (adjusted odds ratio: 0.69, 95% confidence interval: 0.27–1.80).

Conclusion Bacteria traditionally considered to be more pathogenic outside of pregnancy do not progress to pyelonephritis at higher rates than E. coli in pregnancy, and are associated with similar pyelonephritis-related morbidity. Larger studies are needed to confirm these findings.

Key Points
Learning dynamical systems in noise using convolutional neural networks
Authors: Mukhopadhyay Sumona , Banerjee Santo
Published: October 2020

The problem of distinguishing deterministic chaos from non-chaotic dynamics has been an area of active research in time series analysis. Since noise contamination is unavoidable, it renders deterministic chaotic dynamics corrupted by noise to appear in close resemblance to stochastic dynamics. As a result, the problem of distinguishing noise-corrupted chaotic dynamics from randomness based on observations without access to the measurements of the state variables is difficult. We propose a new angle to tackle this problem by formulating it as a multi-class classification task. The task of classification involves allocating the observations/measurements to the unknown state variables in order to find the nature of these unobserved internal state variables. We employ signal and image processing based methods to characterize the different system dynamics. A deep learning technique using a state-of-the-art image classifier known as the Convolutional Neural Network (CNN) is designed to learn the dynamics. The time series are transformed into textured images of spectrogram and unthresholded recurrence plot (UTRP) for learning stochastic and deterministic chaotic dynamical systems in noise. We have designed a CNN that learns the dynamics of systems from the joint representation of the textured patterns from these images, thereby solving the problem as a pattern recognition task. The robustness and scalability of our approach is evaluated at different noise levels. Our approach demonstrates the advantage of applying the dynamical properties of chaotic systems in the form of joint representation of UTRP images along with spectrogram to improve learning dynamical systems in colored noise.
The importance of contacts in Cu2GeTe3 phase change memory devices
Authors: Shindo Satoshi , Shuang Yi , Hatayama Shogo , Saito Yuta , Fons Paul , Kolobov Alexander V. , Kobayashi Keisuke , Sutou Yuji
Published: October 2020

Cu2GeTe3 (CGT) is a promising phase change material for phase change random access memory (PCRAM) applications because of its high thermal stability in the amorphous phase and its capability to undergo rapid phase change. In this paper, the electrical conduction mechanism of a CGT memory device fabricated using W electrodes (W/CGT) was investigated using current–voltage (I–V) measurements and angle resolved hard x-ray photoelectron spectroscopy (AR-HAXPES). The I–V characteristics of the W/CGT memory device were found to display non-linear behavior in the RESET (amorphous) state, while linear behavior was observed in the SET (crystalline) state, indicating that the W/CGT memory device exhibited Schottky conduction in the RESET state, but Ohmic conduction in the SET state. The effective Schottky barrier height was found to increase linearly as the ideality factor decreased to unity with the ideal W/CGT Schottky barrier height in the RESET state estimated to be 0.33 eV, a value in good agreement with the directly measured Schottky barrier height of 0.35 eV between W and amorphous CGT by AR-HAXPES measurements. These results suggest that the interface between the metal electrode and the phase change material plays an important role in PCRAM devices, and its comprehensive understanding is necessary for future application development.
Control of magnetic properties in spinel ZnFe2O4 thin films through intrinsic defect manipulation
Authors: Zviagin V. , Sturm C. , Esquinazi P. D. , Grundmann M. , Schmidt-Grund R.
Published: October 2020

We present a systematic study of the magnetic properties of ZnFe2O4 thin films fabricated by pulsed laser deposition at low and high oxygen partial pressure and annealed in oxygen and argon atmosphere, respectively. The as-grown films show strong magnetization, closely related to a non-equilibrium distribution of defects, namely, Fe cations among tetrahedral and octahedral lattice sites. While the concentration of tetrahedral Fe cations declines after argon treatment at 250 °C, the magnetic response is enhanced by the formation of oxygen vacancies, evident by the increase in near-infrared absorption due to the Fe2+–Fe3+ exchange. After annealing at temperatures above 300 °C, the weakened magnetic response is related to a decline in disorder with a partial recrystallization toward a less defective spinel configuration.
Macroscopic surface charges from microscopic simulations
Authors: Sayer Thomas , Cox Stephen J.
Published: October 2020

Attaining accurate average structural properties in a molecular simulation should be considered a prerequisite if one aims to elicit meaningful insights into a system’s behavior. For charged surfaces in contact with an electrolyte solution, an obvious example is the density profile of ions along the direction normal to the surface. Here, we demonstrate that, in the slab geometry typically used in simulations, imposing an electric displacement field D determines the integrated surface charge density of adsorbed ions at charged interfaces. This allows us to obtain macroscopic surface charge densities irrespective of the slab thickness used in our simulations. We also show that the commonly used Yeh–Berkowitz method and the “mirrored slab” geometry both impose vanishing integrated surface charge densities. We present results both for relatively simple rocksalt (1 1 1) interfaces and the more complex case of kaolinite’s basal faces in contact with an aqueous electrolyte solution.
Adjustable charge states of nitrogen-vacancy centers in low-nitrogen diamond after electron irradiation and subsequent annealing
Authors: Guo Ruiang , Wang Kaiyue , Zhang Yufei , Xiao Zunpeng , Jia Gangyuan , Wang Hongxing , Wu Yaqiao , Tian Yuming
Published: October 2020

In this work, we investigate the photoluminescence spectra of nitrogen-vacancy (NV) centers in low-nitrogen diamond under 200 keV electron irradiation. We discuss the dependence of NV center charge states on annealing temperature, laser excitation power, and measurement temperature. The results show that the NV centers in low-nitrogen diamond are more likely to exist in the form of NV0 centers. Annealing breaks the charge balance between two charged NV centers, and, as the annealing temperature increases (300–800 °C), NV− centers are converted into NV0 centers. Meanwhile, the NV intensities significantly increase when the nitrogen atoms capture the vacancies after electron irradiation and subsequent annealing. With increases in laser power, the NV− centers are more prone to Auger recombination, and thus, the NV− centers are converted into NV0 centers. In addition, the NV centers are quenched by increases in measurement temperature, but the measurement temperature does not affect their intensity ratio. This result indicates that low-nitrogen diamond becomes more likely to form stable NV0 and NV− centers at different measurement temperatures.
Spin orbit torque switching of synthetic Co/Ir/Co trilayers with perpendicular anisotropy and tunable interlayer coupling
Authors: Ma Qinli , Li Yufan , Choi Young-suk , Chen Wei-Chuan , Han Shu Jen , Chien C. L.
Published: October 2020

Spin orbit torque (SOT) has attracted much attention as an energy efficient electrical method to switch the magnetization in single magnetic layer with both in-plane and perpendicular anisotropy. Here, we report SOT switching of synthetic antiferromagnetic and ferrimagnetic Co/Ir/Co trilayers, where the net magnetization and the interlayer coupling strength are highly controllable. A weak external field dependence of the SOT switching was observed due to the robust domain wall structure in the trilayer. The switching current density was observed to scale inversely with the net magnetization. For trilayers with the same net magnetization, switching current is independent of the layer order because switching in the thicker Co layer dominates. In both ferromagnetic and antiferromagetic regimes, the switching current reflects the interlayer coupling strength.
Kinematics of one-dimensional spherical shock waves in interstellar van der Waals gas clouds
Authors: Singh Mayank , Chauhan Astha , Sharma Kajal , Arora Rajan
Published: October 2020

In this work, a system of non-linear partial differential equations, which describes one-dimensional motion of an inviscid, self-gravitating, and spherically symmetric van der Waals gas cloud, is considered. By using the method based on the kinematics of shock waves, the evolution equation for spherical shock wave in an interstellar van der Waals gas cloud is derived. By applying the truncation approximation procedure, an infinite system of transport equations, which governs the shock propagation, is derived to study the kinematics of shock waves for the one-dimensional motion. The first, second, and third order transport equations, which describe the shock strength and the induced discontinuity behind it, are used to analyze the decay and growth behavior of the shock waves in a non-ideal gas. The results are obtained for the exponent obtained from the first, second, and third order approximations and compared with the results obtained by Whitham’s characteristic rule (Chester–Chisnell–Whitham approximation). In addition, the effects of the parameters of non-idealness and cooling–heating function on the evolutionary behavior of shocks are discussed and shown graphically.
Sensitizer–host–annihilator ternary-cascaded triplet energy landscape for efficient photon upconversion in the solid state
Authors: Sakamoto Yuji , Tamai Yasunari , Ohkita Hideo
Published: October 2020

In this paper, we introduce a new strategy for improving the efficiency of upconversion emissions based on triplet–triplet exciton annihilation (TTA-UC) in the solid state. We designed a ternary blend system consisting of a triplet sensitizer (TS), an exciton-transporting host polymer, and a small amount of an annihilator in which the triplet-state energies of the TS, host, and annihilator decrease in this order. The key idea underpinning this concept involves first transferring the triplet excitons generated by the TS to the host and then to the annihilator, driven by the cascaded triplet energy landscape. Because of the small annihilator blend ratio, the local density of triplet excitons in the annihilator domain is higher than those in conventional binary TS/annihilator systems, which is advantageous for TTA-UC because TTA is a density-dependent bimolecular reaction. We tracked the triplet exciton dynamics in the ternary blend film by transient absorption spectroscopy. Host triplet excitons are generated through triplet energy transfer from the TS following intersystem crossing in the TS. These triplet excitons then diffuse in the host domain and accumulate in the annihilator domain. The accumulated triplet excitons undergo TTA to generate singlet excitons that are higher in energy than the excitation source, resulting in UC emission. Based on the excitation-intensity and blend-ratio dependences of TTA-UC, we found that our concept has a positive impact on accelerating TTA.
Point vortices dynamics on a rotating sphere and modeling of global atmospheric vortices interaction
Authors: Mokhov Igor I. , Chefranov Sergey G. , Chefranov Alexander G.
Published: October 2020

It is shown that the hydrodynamics equations for a thin spherical liquid layer are satisfied by the stream function of a pair of antipodal point vortices (APVs), in contrast to the stream function of a single point vortex on a sphere with a background of a uniform opposite sign vorticity. A simple zero solution of the equation of the absolute vorticity conservation is used for bypassing the well-known nonlinear problem of a point vortices interaction with a regular vorticity field, and an exact solution for the APV dynamics problem on a rotating sphere is obtained. Due to this, a new stable stationary solution for the dynamics of APV is obtained, which can model the dynamics of the global vortex structures, such as atmospheric centers of action.
High-color-rendering-index phosphor-free InGaN-based white light-emitting diodes by carrier injection enhancement via V-pits
Authors: Iida Daisuke , Zhuang Zhe , Kirilenko Pavel , Velazquez-Rizo Martin , Ohkawa Kazuhiro
Published: October 2020

We herein report the growth of phosphor-free InGaN-based white light-emitting diodes (LEDs) by metalorganic vapor-phase epitaxy. The active region consists of blue and red InGaN quantum wells (QWs). To improve the current injection and generate broadband emission, the V-pit structures in the LEDs were fabricated intentionally before growing the QWs. The monolithic white LEDs emit in the range of 410–770 nm and, by tuning the injection current, can cover correlated color temperature (CCT) values corresponding to warm white, natural white, and cool white. The color-rendering index (CRI) of the white LEDs reaches 88 at an injection current of 10 mA. At an injection current of 30 mA, the white LEDs exhibit the chromaticity coordinates of (0.320 and 0.334) in the Commission Internationale de l'Eclairage 1931 chromaticity diagram, a CRI of 78, and a CCT of 6110 K.
Aerosol persistence in relation to possible transmission of SARS-CoV-2
Authors: Smith Scott H. , Somsen G. Aernout , van Rijn Cees , Kooij Stefan , van der Hoek Lia , Bem Reinout A. , Bonn Daniel
Published: October 2020

Transmission of SARS-CoV-2 leading to COVID-19 occurs through exhaled respiratory droplets from infected humans. Currently, however, there is much controversy over whether respiratory aerosol microdroplets play an important role as a route of transmission. By measuring and modeling the dynamics of exhaled respiratory droplets, we can assess the relative contribution of aerosols to the spreading of SARS-CoV-2. We measure size distribution, total numbers, and volumes of respiratory droplets, including aerosols, by speaking and coughing from healthy subjects. Dynamic modeling of exhaled respiratory droplets allows us to account for aerosol persistence times in confined public spaces. The probability of infection by inhalation of aerosols when breathing in the same space can then be estimated using current estimates of viral load and infectivity of SARS-CoV-2. The current known reproduction numbers show a lower infectivity of SARS-CoV-2 compared to, for instance, measles, which is known to be efficiently transmitted through the air. In line with this, our study of transmission of SARS-CoV-2 suggests that aerosol transmission is a possible but perhaps not a very efficient route, in particular from non-symptomatic or mildly symptomatic individuals that exhibit low viral loads.
Fluorine-containing ruthenium-based olefin metathesis catalysts
Authors: Masoud Salekh M. , Vorobyeva Daria V. , Petropavlovskikh Dmitry A. , Bruneau Christian , Osipov Sergey N.
Published: October 2020

The review summarizes literature data on the methods for the introduction of fluorine atoms and fluoralkyl groups into different ligands to construct metathesis-active ruthenium carbene complexes. It also analyzes the influence of fluorinated ligands on the catalytic activity of the complexes. The choice, structure and positions of fluorinated substituents in NHC ligands are generally dictated by the desire to increase the electrophilicity of the ruthenium atom due to the electron-withdrawing effect of fluorine atoms and fluoroalkyl groups, resulting, as a rule, in an increase in the activity of the ruthenium complex. In catalysts with unsymmetrical fluorine-containing NHC ligands, there is a possibility of additional Ru–F coordination, making the complexes much more stable and, consequently, more active. The presence of fluorine in chelating alkylidene ligands provides an increase in the catalyst initiation rate due to a weakening of the ruthenium – heteroatom bond. Besides, the introduction of polyfluoroalkyl groups into ligands solves the problem of catalyst recovery using fluorous biphasic systems for reuse.

The bibliography includes 172 references.
RETRACTED: A global network of marine protected areas for food
Authors: Cabral Reniel B. , Bradley Darcy , Mayorga Juan , Goodell Whitney , Friedlander Alan M. , Sala Enric , Costello Christopher , Gaines Steven D.
Published: October 2020

Marine protected areas (MPAs) are conservation tools that are increasingly implemented, with growing national commitments for MPA expansion. Perhaps the greatest challenge to expanded use of MPAs is the perceived trade-off between protection and food production. Since MPAs can benefit both conservation and fisheries in areas experiencing overfishing and since overfishing is common in many coastal nations, we ask how MPAs can be designed specifically to improve fisheries yields. We assembled distribution, life history, and fisheries exploitation data for 1,338 commercially important stocks to derive an optimized network of MPAs globally. We show that strategically expanding the existing global MPA network to protect an additional 5% of the ocean could increase future catch by at least 20% via spillover, generating 9 to 12 million metric tons more food annually than in a business-as-usual world with no additional protection. Our results demonstrate how food provisioning can be a central driver of MPA design, offering a pathway to strategically conserve ocean areas while securing seafood for the future.
Stimulation of soluble guanylate cyclase exerts antiinflammatory actions in the liver through a VASP/NF-κB/NLRP3 inflammasome circuit
Authors: Flores-Costa Roger , Duran-Güell Marta , Casulleras Mireia , López-Vicario Cristina , Alcaraz-Quiles José , Diaz Alba , Lozano Juan J. , Titos Esther , Hall Katherine , Sarno Renee , Masferrer Jaime L. , Clària Joan
Published: October 2020

Significance

Fatty liver, which is an initial step in the development of more severe complications such as liver cirrhosis, is prevalent worldwide in our society. This study demonstrates that stimulation of soluble guanylate cyclase (sGC), an enzyme producing the second messenger cGMP, protects against the most common features of fatty liver, namely inflammation and fibrosis, in animal models of the disease. Our study also provides an explanation for this protection and describes how sGC stimulation blocks the inflammasome (a protein complex responsible for the production of the potent proinflammatory cytokine interleukin-1β) in liver macrophages. The results of this study support the investigation of sGC stimulators, which are already approved for treatment in other conditions, in patients with fatty liver disease.
Outsized nutrient contributions from small tributaries to a Great Lake
Authors: Mooney Robert J. , Stanley Emily H. , Rosenthal William C. , Esselman Peter C. , Kendall Anthony D. , McIntyre Peter B.
Published: October 2020

Significance

Excessive nutrient inputs from tributary streams and rivers contribute to harmful algal blooms and coastal ecosystem degradation worldwide. However, the role that small tributaries play in coastal nutrient dynamics remains unknown because most monitoring and regulatory efforts focus only on the largest tributaries. We combined a 6-d sampling effort with discharge modeling to characterize nutrient inputs from nearly all watersheds draining to the world’s fifth largest lake. We found that streams are particularly likely to promote eutrophication in coastal ecosystems because they deliver water with higher concentrations of nutrients that are readily available to algae. Thus, our findings indicate that efforts to control nutrient loading could be enhanced by looking beyond the largest tributaries to include smaller streams.
Evidence for massive emission of methane from a deep‐water gas field during the Pliocene
Authors: Foschi Martino , Cartwright Joseph A. , MacMinn Christopher W. , Etiope Giuseppe
Published: October 2020

Significance

A major uncertainty in the sources of atmospheric methane is the role of geologic seepage from petroleum-bearing sedimentary basins. Hydrocarbon seeps located onshore, shallow offshore, and coastal areas can play a major role. Methane released by deep ocean seeps typically does not reach the atmosphere. Here, we provide evidence for a single, large, and sudden expulsion of methane from a deep‐water reservoir during the Pliocene. We use geophysical evidence and fluid-flow modeling to estimate that this single event would have amounted to ∼10% of present‐day annual natural methane emissions. Although no ultraseepage events, such as this one, have been documented in modern times, the relatively common geologic circumstances of this type of event suggest that they are not exceptional.
Phosphatidylinositol-4-kinase IIα licenses phagosomes for TLR4 signaling and MHC-II presentation in dendritic cells
Authors: López-Haber Cynthia , Levin-Konigsberg Roni , Zhu Yueyao , Bi-Karchin Jing , Balla Tamas , Grinstein Sergio , Marks Michael S. , Mantegazza Adriana R.
Published: October 2020

Significance

Dendritic cells (DCs) play a key role at the interface between innate and adaptive immunity. DCs continuously sample their microenvironment, respond to microbial cues by signaling through pattern-recognition receptors such as Toll-like receptors (TLRs), and present bacterial antigens to adaptive immune cells. We show that the lipid kinase phosphatidylinositol-4-kinase IIα (PI4KIIα) is required to generate a phosphatidylinositol-4-phosphate pool on DC phagosomes that allows binding of the TLR sorting adaptor TIRAP and promotes TLR4 phagosomal signaling to proinflammatory cytokine production, phagosomal membrane tubule formation, and presentation of phagocytosed antigens. PI4KIIα therefore ensures phagosomal identity and autonomous signaling to initiate antimicrobial immune responses in DCs.
Comprehensive characterization of amino acid positions in protein structures reveals molecular effect of missense variants
Authors: Iqbal Sumaiya , Pérez-Palma Eduardo , Jespersen Jakob B. , May Patrick , Hoksza David , Heyne Henrike O. , Ahmed Shehab S. , Rifat Zaara T. , Rahman M. Sohel , Lage Kasper , Palotie Aarno , Cottrell Jeffrey R. , Wagner Florence F. , Daly Mark J. , Campbell Arthur J. , Lal Dennis
Published: October 2020

Significance

Recent large-scale sequencing efforts have enabled the detection of millions of missense variants. Elucidating their functional effect is of crucial importance but challenging. We approach this problem by performing a wide-scale characterization of missense variants from 1,330 disease-associated genes using >14,000 protein structures. We identify 3D features associated with pathogenic and benign variants that unveiled the mutations’ effect at the molecular level. We further extend our analysis to account for the different essential structural regions in proteins performing different functions. By analyzing variants from 24 gene groups encoding for different protein functional families, we capture function-specific characteristics of missense variants, which match the experimental readouts. We show that our results derived using structural data will effectively inform variant interpretation.
Anionic nanoparticle-induced perturbation to phospholipid membranes affects ion channel function
Authors: Foreman-Ortiz Isabel U. , Liang Dongyue , Laudadio Elizabeth D. , Calderin Jorge D. , Wu Meng , Keshri Puspam , Zhang Xianzhi , Schwartz Michael P. , Hamers Robert J. , Rotello Vincent M. , Murphy Catherine J. , Cui Qiang , Pedersen Joel A.
Published: October 2020

Significance

Design of nanoscale materials for applications that interface with biological systems requires that mechanisms of nanoparticle interaction with cellular membranes be understood, both to improve performance and to assess nanomaterial safety. We integrated experimental and computational approaches to resolve the outstanding question of whether the function of membrane-embedded ion channels can be perturbed via nanoparticle-induced modulation of membrane mechanical properties. We show that anionic nanoparticles disrupt channel activity indirectly by perturbing local properties of the surrounding lipid bilayer. Our results indicate that nanoparticle effects on membrane protein function do not require direct interaction; effects can be mediated via changes in bilayer mechanical properties. Such indirect effects warrant consideration in nanomaterial safety evaluations and suggest potential applications in modulating cellular function.
Climate drives the geography of marine consumption by changing predator communities
Authors: Whalen Matthew A. , Whippo Ross D. B. , Stachowicz John J. , York Paul H. , Aiello Erin , Alcoverro Teresa , Altieri Andrew H. , Benedetti-Cecchi Lisandro , Bertolini Camilla , Bresch Midoli , Bulleri Fabio , Carnell Paul E. , Cimon Stéphanie , Connolly Rod M. , Cusson Mathieu , Diskin Meredith S. , D’Souza Elrika , Flores Augusto A. V. , Fodrie F. Joel , Galloway Aaron W. E. , Gaskins Leo C. , Graham Olivia J. , Hanley Torrance C. , Henderson Christopher J. , Hereu Clara M. , Hessing-Lewis Margot , Hovel Kevin A. , Hughes Brent B. , Hughes A. Randall , Hultgren Kristin M. , Jänes Holger , Janiak Dean S. , Johnston Lane N. , Jorgensen Pablo , Kelaher Brendan P. , Kruschel Claudia , Lanham Brendan S. , Lee Kun-Seop , Lefcheck Jonathan S. , Lozano-Álvarez Enrique , Macreadie Peter I. , Monteith Zachary L. , O’Connor Nessa E. , Olds Andrew D. , O’Leary Jennifer K. , Patrick Christopher J. , Pino Oscar , Poore Alistair G. B. , Rasheed Michael A. , Raymond Wendel W. , Reiss Katrin , Rhoades O. Kennedy , Robinson Max T. , Ross Paige G. , Rossi Francesca , Schlacher Thomas A. , Seemann Janina , Silliman Brian R. , Smee Delbert L. , Thiel Martin , Unsworth Richard K. F. , van Tussenbroek Brigitta I. , Vergés Adriana , Yeager Mallarie E. , Yednock Bree K. , Ziegler Shelby L. , Duffy J. Emmett
Published: October 2020

Significance

Consumption transfers energy and materials through food chains and fundamentally influences ecosystem productivity. Therefore, mapping the distribution of consumer feeding intensity is key to understanding how environmental changes influence biodiversity, with consequent effects on trophic transfer and top–down impacts through food webs. Our global comparison of standardized bait consumption in shallow coastal habitats finds a peak in feeding intensity away from the equator that is better explained by the presence of particular consumer families than by latitude or temperature. This study complements recent demonstrations that changes in biodiversity can have similar or larger impacts on ecological processes than those of climate.
Myelination of peripheral nerves is controlled by PI4KB through regulation of Schwann cell Golgi function
Authors: Baba Takashi , Alvarez-Prats Alejandro , Kim Yeun Ju , Abebe Daniel , Wilson Steve , Aldworth Zane , Stopfer Mark A. , Heuser John , Balla Tamas
Published: October 2020

Significance

We identify PI4KB, a phosphoinositide kinase that controls the functions of the Golgi compartment, as a critical regulator of myelination of peripheral nerves. Genetic inactivation of PI4KB, specifically in Schwann cells in mice, causes hypomyelination of large diameter axons and impairs engulfment of small diameter fibers by nonmyelinating Schwann cells. Sciatic nerves of mutant mice show depletion of cholesterol, sphingomyelin and phosphatidylethanolamine, as well as defects in protein glycosylation.
Abnormal morphology biases hematocrit distribution in tumor vasculature and contributes to heterogeneity in tissue oxygenation
Authors: Bernabeu Miguel O. , Köry Jakub , Grogan James A. , Markelc Bostjan , Beardo Albert , d’Avezac Mayeul , Enjalbert Romain , Kaeppler Jakob , Daly Nicholas , Hetherington James , Krüger Timm , Maini Philip K. , Pitt-Francis Joe M. , Muschel Ruth J. , Alarcón Tomás , Byrne Helen M.
Published: October 2020

Significance

Oxygen heterogeneity in solid tumors is recognized as a limiting factor for therapeutic efficacy. This heterogeneity arises from the abnormal tumor vascular structure. We investigate the role that anomalies in red blood cell transport plays in establishing oxygen heterogeneity in tumor tissue. We introduce a metric to characterize tumor vasculature (mean vessel length-to-diameter ratio,

λ

) and demonstrate how it predicts tissue-oxygen heterogeneity. We also report an increase in

λ

following treatment with the antiangiogenic agent DC101. Together, we propose

λ

as an effective way of monitoring the action of antiangiogenic agents and a proxy measure of oxygen heterogeneity in tumor tissue. Unraveling the causal relationship between tumor vascular structure and tissue oxygenation will pave the way for new personalized therapeutic approaches.
RNA-binding protein DDX3 mediates posttranscriptional regulation of androgen receptor: A mechanism of castration resistance
Authors: Vellky Jordan E. , McSweeney Sean T. , Ricke Emily A. , Ricke William A.
Published: October 2020

Significance

Little is known regarding the mechanisms involved in loss of androgen receptor (AR) function in the development of castration resistance. Recently, the clinical use of new potent AR therapies has led to the emergence of a new lethal subtype of castration-resistant prostate cancer (CRPC) lacking AR protein and signaling, termed ARL/negative CRPC. We discovered that DDX3 (DEAD-box helicase 3 X-linked) is a key repressor of AR protein translation—a mechanism that leads to development of castration resistance. Inhibition of DDX3 in ARL/negative CRPC promotes the expression of AR protein/signaling and hence sensitivity to hormone therapy. These data provide a molecular mechanism for hormone action and describe a synthetic lethality approach to the clinical treatment of therapy-resistant diseases such as CRPC.
Modular genetic control of social status in a cichlid fish
Authors: Alward Beau A. , Laud Vibhav A. , Skalnik Christopher J. , York Ryan A. , Juntti Scott A. , Fernald Russell D.
Published: October 2020

Significance

Social rank along a hierarchy determines physiological state and behavioral performance. A ubiquitous feature of social hierarchies is the communication of rank through nonphysical signaling systems (e.g., coloration) and aggression, traits that correlate with the reproductive status of an individual. Despite the links identified between social status, physiology, and behavior, the molecular basis of social status is not known. Here, we genetically dissect social status in the African cichlid fish
Astatotilapia burtoni
using CRISPR/Cas9 gene editing. We discovered that two paralogous androgen receptor genes control social status in a highly modular manner. This type of coordination of social status may be fundamental across species that rely on social information to optimally guide physiology and behavior.
Harnessing
64
Cu/
67
Cu for a theranostic approach to pretargeted radioimmunotherapy
Authors: Keinänen Outi , Fung Kimberly , Brennan James M. , Zia Nicholas , Harris Matt , van Dam Ellen , Biggin Colin , Hedt Amos , Stoner Jon , Donnelly Paul S. , Lewis Jason S. , Zeglis Brian M.
Published: October 2020

Significance

Radioimmunotherapy is predicated on harnessing the exquisite specificity of antibodies to deliver cytotoxic radiation to tumors. Yet the long circulation time of radioimmunoconjugates leads to high radiation doses to healthy tissues. Pretargeted radioimmunotherapy (PRIT) circumvents this problem by decoupling the antibody and radionuclide, injecting the former prior to the latter, and empowering the two components to combine at the tumor. We have leveraged bioorthogonal click chemistry, a colorectal cancer-targeting antibody, and a pair radioligands bearing radioisotopes of copper—positron-emitting copper-64 and beta particle-emitting copper-67—to create a pretargeting system that enables both theranostic positron emission tomography and PRIT. We believe that the incorporation of theranostic imaging into PRIT regimens could be instrumental in the clinical success of the modality.
Characterization of systemic genomic instability in budding yeast
Authors: Sampaio Nadia M. V. , Ajith V. P. , Watson Ruth A. , Heasley Lydia R. , Chakraborty Parijat , Rodrigues-Prause Aline , Malc Ewa P. , Mieczkowski Piotr A. , Nishant Koodali T. , Argueso Juan Lucas
Published: October 2020

Significance

Mutations are generally thought to accumulate independently and gradually over many generations. Here, we combined complementary experimental approaches in budding yeast to track the appearance of chromosomal changes resulting in loss-of-heterozygosity. In contrast to the prevailing model, our results provide evidence for the existence of a path for nonindependent accumulation of multiple chromosomal alteration events over a few generations. These results are analogous to recent reports of bursts of genomic instability in human cells. The experimental model we describe provides a system to further dissect the fundamental biological processes underlying such punctuated bursts of mutation accumulation.
Multistep substrate binding and engagement by the AAA+ ClpXP protease
Authors: Saunders Reuben A. , Stinson Benjamin M. , Baker Tania A. , Sauer Robert T.
Published: October 2020

Significance

AAA+ proteases play key regulatory and quality control roles in all domains of life. These destructive enzymes recognize damaged, unneeded, or regulatory proteins via specific degrons and unfold them prior to processive degradation. Here, we show that
Escherichia coli
ClpXP, a model AAA+ protease, recognizes ssrA-tagged substrates in a multistep binding and engagement reaction. Together with recent cryo-electron microscopy (cryo-EM) structures, our experiments reveal how ClpXP transitions from a machine that checks potential substrates for appropriate degrons to one that can unfold and translocate almost any protein. Other AAA+ proteases in organelles and bacteria are likely to use similar mechanisms to specifically identify and then destroy their target proteins.