bluuebunny/crossref_metadata_2025 huggingface dataset:
Alcohol-Directed ortho-C–H Alkenylation
Authors: Li Li , Liu Qinglan , Chen Jiean , Huang Yong
Published: May 2019

We report a simple and mild dehydrogenative cross-coupling reaction of unprotected arylethanols and acrylates. Unlike the case of previous reactions, in which prior functionalization of the substrate with a metal-coordinating site was required, free primary, secondary, or tertiary hydroxy groups were found to be effective directing groups for the ortho-C–H palladation and subsequent olefination.
Metallaelectro-Catalyzed C–H Activation by Weak Coordination
Authors: Qiu Youai , Struwe Julia , Ackermann Lutz
Published: May 2019

The merger of organometallic C–H activation with electrocatalysis has emerged as a powerful strategy for molecular synthesis, avoiding the use of toxic and expensive chemical oxidants in stoichiometric quantities. This review summarizes recent progress in transition-metal-catalyzed electrochemical C–H activation by weak chelation assistance until March 2019.

1 Introduction

2 Ruthenaelectro-Catalyzed C–H Activation

3 Rhodaelectro-Catalyzed C–H Activation

4 Iridaelectro-Catalyzed C–H Activation

5 Summary and Outlook
Opening New Horizons in the Treatment of Childhood Onset Leukodystrophies
Authors: Schiller Stina , Henneke Marco , Gärtner Jutta
Published: May 2019

Leukodystrophies (LDs) predominantly affect the white matter of the central nervous system and its main component, the myelin. The majority of LDs manifests in infancy with progressive neurodegeneration. Main clinical signs are intellectual and motor function losses of already attained developmental skills. Classical LDs include lysosomal storage disorders like metachromatic leukodystrophy (MLD), peroxisomal disorders like X-linked adrenoleukodystrophy (X-ALD), disorders of mitochondrial dysfunction, and myelin protein defects like Pelizaeus-Merzbacher disease. So far, there are only single LD disorders with effective treatment options in an early stage of disease. The increasing number of patients diagnosed with LDs emphasizes the need for novel therapeutic options. Impressive advances in biotechnology have not only led to the continuous identification of new disease genes for so far unknown LDs but also led to new effective neuroprotective and disease-modifying therapeutic approaches. This review summarizes ongoing and novel innovative treatment options for LD patients and their challenges. It includes in vitro and in vivo approaches with focus on stem cell and gene therapies, intrathecal substrate or enzyme replacement, and genome editing.
An Assessment of Globe Position Dynamics following Transcranial Lateral and Superior Orbital Wall Resections without Rigid Reconstruction: A Case Series of 55 Patients
Authors: Krug Randall G. , Bradley Elizabeth A. , Van Gompel Jamie J.
Published: May 2019

Background There is no consensus exists regarding which reconstructive approach, if any, should be used after performing transcranial lateral orbital wall resections. Rigid reconstruction is often done to prevent enophthalmos; however, it is not clear if this is a risk with extensive orbital wall resections for transcranial surgery.

Objective To assess globe position dynamics in patients that underwent transcranial lateral and superior orbital wall resections without rigid reconstruction to determine if enophthalmos is a significant risk.

Methods Preoperative (PO) and postoperative data were retrospectively collected from the electronic medical records of 55 adult patients undergoing lateral and superior orbital wall resections as part of a skull base approach. The globe positions were assessed radiologically at all available time points and used to track relative globe displacements over time.

Results An evaluation of PO variables identified a relationship between maximum lesion diameters and globe positions dynamics. The composition of globe position presentations in the population remained relatively stable over time, with only 1 out of 55 patients (1.81%) developing postoperative enophthalmos. An assessment of mean globe displacements revealed improvements in the patients presenting with PO exophthalmos, and stability in the patients presenting with normal PO globe positions.

Conclusions Excellent results in long-term postoperative globe position dynamics can be achieved without the use of rigid reconstruction after transcranial lateral and superior orbital wall resections, regardless of the PO globe positioning.
Making the smart meter social promotes long-term energy conservation
Authors: De Dominicis Stefano , Sokoloski Rebecca , Jaeger Christine M. , Schultz P. Wesley
Published: May 2019

Managing demand for energy is becoming increasingly important for efforts to shift toward more sustainable lifestyles. Managing demand for energy involves changes in human behaviour, and can be achieved through more efficient uses of technology, and through conservation. Feedback is often cited as a critical tool to promote energy conservation and efficiency, but recent studies in behavioural science suggest that feedback alone may not be enough to promote lasting changes in behaviour. As an alternative, recent studies have shown the effectiveness of providing residents with normative feedback, rather than simple personal feedback. The current study analyses the impact of real-time feedback on residential electricity consumption over a two-year period. Results showed that when framed as a social comparison, feedback resulted in long-term reductions in household electricity consumption. Importantly, greater reductions were observed for households that identified more strongly with the normative referent group. Theoretical implications of the findings for behavioural science and the corresponding practical implications for fostering long-term sustainable behaviours are discussed.
Rapid mixing of colliding picoliter liquid droplets delivered through-space from piezoelectric-actuated pipettes characterized by time-resolved fluorescence monitoring
Authors: Wu Jamie L. Y. , Tellkamp Friedjof , Khajehpour Mazdak , Robertson Wesley D. , Miller R. J. Dwayne
Published: May 2019

Rapid mixing of aqueous solutions is a crucial first step to study the kinetics of fast biochemical reactions with high temporal resolution. Remarkable progress toward this goal has been made through the development of advanced stopped-flow mixing techniques resulting in reduced dead times, and thereby extending reaction monitoring capabilities to numerous biochemical systems. Concurrently, piezoelectric actuators for through-space liquid droplet sample delivery have also been applied in several experimental systems, providing discrete picoliter sample volume delivery and precision sample deposition onto a surface, free of confinement within microfluidic devices, tubing, or other physical constraints. Here, we characterize the inertial mixing kinetics of two aqueous droplets (130 pl) produced by piezoelectric-actuated pipettes, following droplet collision in free space and deposition on a surface in a proof of principle experiment. A time-resolved fluorescence system was developed to monitor the mixing and fluorescence quenching of 5-carboxytetramethylrhodamine (5-Tamra) and N-Bromosuccinimide, which we show to occur in less than 10 ms. In this respect, this methodology is unique in that it offers millisecond mixing capabilities for very small quantities of discrete sample volumes. Furthermore, the use of discrete droplets for sample delivery and mixing in free space provides potential advantages, including the elimination of the requirement for a physical construction as with microfluidic systems, and thereby makes possible and extends the experimental capabilities of many systems.
Chimera states in coupled logistic maps with additional weak nonlocal topology
Authors: Chandran P. , Gopal R. , Chandrasekar V. K. , Athavan N.
Published: May 2019

We demonstrate the occurrence of coexisting domains of partially coherent and incoherent patterns or simply known as chimera states in a network of globally coupled logistic maps upon addition of weak nonlocal topology. We find that the chimera states survive even after we disconnect nonlocal connections of some of the nodes in the network. Also, we show that the chimera states exist when we introduce symmetric gaps in the nonlocal coupling between predetermined nodes. We ascertain our results, for the existence of chimera states, by carrying out the recurrence quantification analysis and by computing the strength of incoherence. We extend our analysis for the case of small-world networks of coupled logistic maps and found the emergence of chimeralike states under the influence of weak nonlocal topology.
3D-reconstructions for the estimation of ice particle’s volume using a two-views interferometric out-of-focus imaging set-up
Authors: Brunel M. , Delestre B. , Talbi M.
Published: May 2019

The characterization of ice crystals has important applications in airborne research and civil aviation. Interferometric out-of-focus imaging is a promising technique. We investigate in this study the impact of the 3D shape reconstruction of the particles from a pair of interferometric images on the estimation of the ice particle’s volume. An interferometric image gives indeed the 2D autocorrelation of the particle’s shape. As different shapes can exhibit a similar 2D autocorrelation, particles of different shapes can have similar interferometric images. In this study, the volume of ice particles is estimated from a pair of interferometric images (with two perpendicular angles of view). The relative error in the particle’s volume estimation is shown to be around ΔV V≈30% depending on the choice of the initial 3D particle’s shape. It appears that the choice of the shape of the particle for both angles of view has a lower impact on the estimation of the particle’s volume than the other sources of errors due to image acquisitions themselves.
A fast and accurate piezoelectric actuator modeling method based on truncated least squares support vector regression
Authors: Liu Xiangdong , Ma Zhibiao , Mao Xuefei , Shan Jinjun , Wang Yijun
Published: May 2019

In order to improve the applicability of piezoelectric actuators (PEAs) in precision positioning, least squares support vector regression (LS-SVR) is applied to model hysteresis in PEAs due to its high modeling accuracy and fast convergence speed. However, low robustness of LS-SVR makes modeling accuracy susceptible to noises, which makes LS-SVR hysteresis models difficult to be applied in engineering environment. In this article, a robust truncated least squares support vector regression (T-LSSVR) is proposed. With the truncation strategy, redundancy in the training set is reduced and robustness is improved. Parameters required for T-LSSVR are optimized by particle swarm optimization and cross optimization algorithms. To test the proposed approach, it is applied to predict the hysteresis of PEAs. Results show that the proposed method is more accurate and robust than other versions of LS-SVR when the training set is polluted by noises, and meanwhile reduces the sample size and increases computational efficiency.
Negative capacitance as a diagnostic tool for recombination in purple quantum dot LEDs
Authors: Blauth Christian , Mulvaney Paul , Hirai Tadahiko
Published: May 2019

Impedance spectroscopy is a powerful and nondestructive tool for studying charge carrier dynamics in quantum dot light-emitting diodes (QLEDs). We report here that QLEDs exhibit unique capacitance behavior that strongly depends on the ligand chemistry of the quantum dots (QDs). At low frequencies and under bipolar injection, the capacitance of the QLEDs becomes negative before it returns to positive values at even lower frequencies. This behavior is fundamentally different from that observed in organic light-emitting diodes and is attributed to the accumulation of charge carriers within the ligand shells during operation. The capacitive response depends on both the conductivity and the length of the QD ligands and can be used as a diagnostic tool for understanding the luminescent recombination efficiency of a QLED. We find that short and conductive ligands result in positive device capacitances only and this correlates with enhanced device efficiency.
Chaos, synchronization, and desynchronization in a liquid-fueled diffusion-flame combustor with an intrinsic hydrodynamic mode
Authors: Guan Yu , Li Larry K. B. , Ahn Byeonguk , Kim Kyu Tae
Published: May 2019

We experimentally investigate the nonlinear dynamics of a thermoacoustically self-excited aero-engine combustion system featuring a turbulent swirling liquid-fueled diffusion flame in a variable-length combustor. We focus on the steady-state dynamics via simultaneous measurements of the acoustic pressure in the combustor and the heat release rate (HRR) from the flame. When the combustor length is increased following the onset of thermoacoustic instability, we find that the pressure signal transitions from a period-1 limit cycle to chaos, whereas the HRR signal remains chaotic owing to the presence of an intrinsic hydrodynamic mode in the flame. When the hydrodynamic mode is filtered out of the data, we find that the pressure and HRR signals are in generalized synchronization. However, when the hydrodynamic mode is retained in the data, we find that the pressure and HRR signals are either weakly phase synchronized or desynchronized. This study has two main contributions: (i) it shows that a liquid-fueled diffusion-flame combustor can exhibit dynamics as complex as those of its gaseous-fueled premixed-flame counterparts and (ii) it highlights the need to be exceptionally careful when selecting a diagnostic signal from which to calculate nonlinear measures of self-excited thermoacoustic oscillations, because our experiments show that the pressure and HRR signals can be desynchronized by the presence of a hydrodynamic mode in the flame at a frequency different from that of the dominant thermoacoustic mode.
Numerical modeling of ultrasound heating for the correction of viscous heating artifacts in soft tissue temperature measurements
Authors: Tiennot Thomas , Kamimura Hermes A. S. , Lee Stephen A. , Aurup Christian , Konofagou Elisa E.
Published: May 2019

Measuring temperature during focused ultrasound (FUS) procedures is critical for characterization, calibration, and monitoring to ultimately ensure safety and efficacy. Despite the low cost and the high spatial and temporal resolutions of temperature measurements using thermocouples, the viscous heating (VH) artifact at the thermocouple-tissue interface requires reading corrections for correct thermometric analysis. In this study, a simulation pipeline is proposed to correct the VH artifact arising from temperature measurements using thermocouples in FUS fields. The numerical model consists of simulating a primary source of heating due to ultrasound absorption and a secondary source of heating from viscous forces generated by the thermocouple in the FUS field. Our numerical validation found that up to 90% of the measured temperature rise was due to VH effects. Experimental temperature measurements were performed using thermocouples embedded in fresh chicken breast samples. Temperature corrections were demonstrated for single high-intensity FUS pulses at 3.1 MHz and for multiple pulses (3.1 MHz, 100 Hz, and 500 Hz pulse repetition frequency). The VH accumulated during sonications and produced a temperature increase of 3.1 °C and 15.3 °C for the single and multiple pulse sequences, respectively. The methodology presented here enables the decoupling of the temperature increase generated by absorption and VH. Thus, more reliable temperature measurements can be extracted from thermocouple measurements by correcting for VH.
Damped interfacial oscillation of a particle-embedded viscous drop
Authors: Liu Bo , Sumanasekara Udugama R. , Bhattacharya Sukalyan
Published: May 2019

This article describes how a drop with an embedded particle exhibits interfacial waves with transient decay due to the interplay between capillary and viscous effects. To reveal the damped oscillation of the system properly, the deformation and pressure fields inside the domain are described in terms of complete sets of basis functions. Such representation leads to a matrix formulation which enforces no-slip condition at the solid-liquid interface and ensures correct discontinuity in normal stress due to surface tension at the drop periphery. The resulting characteristic equation involving the natural frequencies and the decay constants is solved numerically to determine these quantities. The matrix expression implies a block-diagonalized structure with two uncoupled blocks corresponding to two distinctly different dynamics. The first of these is related to pure rotational velocities on spherical surfaces which monotonically decay in time without any fluctuation in the absence of any peripheral deformation. By contrast, the second block is associated with the undulation in shape. Due to the restoring features of surface tension, the latter can exhibit underdamped oscillatory modes, if the capillary number Ca is below a critical value. However, even these waves would become overdamped if the critical number is exceeded. These values of Ca for a few most relevant modes are plotted in this paper as functions of particle-to-drop size ratio. Also, the natural frequencies for the underdamped cases as well as the damping constants for all considered modes are presented for different size ratios and capillary numbers. The findings are verified by matching the computed results to a novel boundary layer theory under low capillary number limit. Under the limiting condition, both sets of independent calculations yield the same decay constants and natural frequencies providing mutual validations.
Electrostatic equilibria of non-neutral plasmas confined in a Penning trap with axially varying magnetic field
Authors: Lane R. A. , Ordonez C. A.
Published: May 2019

A procedure for computing the electrostatic equilibria of non-neutral plasmas in a Penning trap with a nonuniform magnetic field by solving Poisson's equation using an iterative method is described. Plasma equilibria in a model Penning trap with high and low field regions are computed. The plasma is assumed to follow the Boltzmann density distribution along magnetic field lines. Correspondence with previous investigations examining similar configurations analytically and using particle-in-cell simulations is found. The relationship between the plasma density in low and high field regions is examined for various plasma temperatures, densities, magnetic mirror ratios, and plasma and electrode radii. An analytical description of the radial density profile in the high field region is developed and compared with the computed equilibria. A concept is described for cooling a positron plasma with laser-cooled ions trapped axially within a high magnetic field region, while antiprotons are trapped axially separated from the laser-cooled ions within a low field region, and the positron plasma extends to both regions.
Rate constants in spatially inhomogeneous systems
Authors: Schile Addison J. , Limmer David T.
Published: May 2019

We present a theory and accompanying importance sampling method for computing rate constants in spatially inhomogeneous systems. Using the relationship between rate constants and path space partition functions, we illustrate that the relative change in the rate of a rare event through space is isomorphic to the calculation of a free energy difference, albeit in a trajectory ensemble. Like equilibrium free energies, relative rate constants can be estimated by importance sampling. An extension to transition path sampling is proposed that combines biased path ensembles and weighted histogram analysis to accomplish this estimate. We show that rate constants can also be decomposed into different contributions, including relative changes in stability, barrier height, and flux. This decomposition provides a means of interpretation and insight into rare processes in complex environments. We verify these ideas with a simple model of diffusion with spatially varying diffusivity and illustrate their utility in a model of ion pair dissociation near an electrochemical interface.
Electron temperature gradient turbulence induced energy flux in the large volume plasma device
Authors: Srivastav Prabhakar , Singh Rameswar , Awasthi L. M. , Sanyasi A. K. , Srivastava P. K. , Sugandhi Ritesh , Singh R.
Published: May 2019

The Large Volume Plasma Device (LVPD) has successfully demonstrated excitation of the Electron Temperature Gradient (ETG) driven turbulence in the finite plasma beta (β∼0.06−0.4) condition, where the threshold condition for ETG turbulence is, ηETG=Ln/LT>2/3 satisfied, where, Ln=1ndndx−1 is the density scale length and LTe=1TedTedx−1 is the temperature scale lengths [Mattoo et al., Phys. Rev. Lett. 108, 255007 (2012)]. The observed mode follows wave vector scaling and frequency ordering as k⊥ρe≤1 ≪ k⊥ρi,  Ωi<ω ≪ Ωe, where k⊥ is the perpendicular wave vector, ρe,  ρi  are Larmor radii of the electron and ion, respectively, and Ωi,  Ωe, ω are the ion, electron gyro frequencies and the mode frequency, respectively. Simultaneous measurement of fluctuations in electron temperature, δTe  ∼ (10−30) %, plasma density, δne ∼ (5−12) %, and potential δVf ∼ (1−10) % are obtained. A strong negative correlation with correlation coefficients Cδn−δφ ∼−0.8 and CδT−δφ ∼−0.9 is observed between the density and potential and temperature and potential fluctuations, respectively. These correlated density, temperature, and potential fluctuations lead to the generation of turbulent heat flux. The measured heat flux is compared with the theoretically estimated heat flux from ETG model equations. The experimental result shows that the net heat flux is directed radially outward.
Plasmon induced brightening of dark exciton in monolayer WSe2 for quantum optoelectronics
Authors: Arora Ankit , Dixit Tejendra , Anil Kumar K. V. , Krishnan Sivarama , Lakshmi Ganapathi K. , Krishnan Ananth , Nayak Pramoda K. , Ramachandra Rao M. S.
Published: May 2019

In the present work, we report plasmon induced brightening of dark excitons (XD) in Au nanoparticle (Au-NP) coated monolayer (1L) WSe2. We observed one order enhancement in photoluminescence (PL) intensity and surface enhanced Raman scattering in Au-NP/1L-WSe2 at room temperature (RT). Temperature dependent PL measurements showed enhanced PL emission from RT down to 100 K in contrast to reduced PL emission which is generally observed for pristine 1L-WSe2. We attribute this effect to the out-of-plane electric field induced by the scattering from Au-NPs, which results in the out-of-plane dipole moment and spin-flip of conduction band electrons in Au-NP/1L-WSe2, making XD bright. Our approach provides a facile way to harness excitonic properties in low-dimensional semiconductors, offering simple strategies for quantum optoelectronics.
Roles of solitary eddy and splash in drift wave–zonal flow system in a linear magnetized plasma
Authors: Arakawa H. , Sasaki M. , Inagaki S. , Kosuga Y. , Kobayashi T. , Kasuya N. , Yamada T. , Nagashima Y. , Kin F. , Fujisawa A. , Itoh K. , Itoh S.-I.
Published: May 2019

We experimentally investigate the roles of drift wave type fluctuations interacting with zonal flow. The drift wave type fluctuations examined in this paper are characterized by nonlinear solitary wave, splash, and solitary eddy [Arakawa et al., Sci. Rep. 6, 33371 (2016)]. Compared to the nonlinear solitary wave, splash has a short lifetime, while solitary eddy has a long lifetime. Excitation/damping of the splash and the solitary eddy are synchronized with zonal perturbation. The roles of the splash and the solitary eddy in transport processes are also discussed. Solitary eddy contributes to momentum transport and accelerates zonal flow. The particle flux driven by the solitary eddy and the splash is in the inward and outward directions, respectively, with similar magnitudes.
Bouncing of a projectile impacting a dense potato-starch suspension layer
Authors: Egawa Kazuya , Katsuragi Hiroaki
Published: May 2019

When a solid projectile is dropped onto a dense non-Brownian-particle suspension, the action of an extremely large resistance force on the projectile results in its drastic deceleration, followed by a rebound. In this study, we perform a set of simple experiments of dropping a solid-projectile impact onto a dense potato-starch suspension. From the kinematic data of the projectile motion, the restitution coefficient and time scale of the rebound are measured. By assuming linear viscoelasticity, the effective transient elasticity and viscosity can be estimated. We additionally estimate the Stokes viscosity on a longer time scale by measuring the slow sinking time of the projectile. The estimated elastic modulus and viscosity are consistent with separately measured previous results. In addition, the effect of mechanical vibration on the viscoelasticity is examined. As a result, we find that the viscoelasticity of the impacted dense suspension is not significantly affected by the mechanical vibration.
Wall-attached clusters for the logarithmic velocity law in turbulent pipe flow
Authors: Hwang Jinyul , Sung Hyung Jin
Published: May 2019

The logarithmic law of the mean velocity is considered a fundamental feature of wall-bounded turbulent flows. The logarithmic velocity law is used widely to model the near-wall turbulence and to predict skin friction. Although classical scaling theory has been used to verify that the velocity profile in the overlap region follows the logarithmic behavior asymptotically, and thus recent experiments have attempted to assess the logarithmic law in large-scale facilities, there is a lack of understanding of the structural basis for the logarithmic law. Here, we show the logarithmic law by extracting the wall-attached structures of the streamwise velocity fluctuations through direct numerical simulation of turbulent pipe flow. The wall-attached structures exhibit self-similar behavior according to their height and have an inverse-scale population density, reminiscent of Townsend’s attached-eddy hypothesis. The wall-normal distributions of the streamwise velocity within the identified structures are conditionally averaged with respect to their height. The velocity profile is reconstructed by superimposing the velocity distributions of the objects that follow the inverse-scale population density. The indicator function of the resulting velocity profile shows a complete plateau for the high-speed structures due to their higher local Reynolds number. These findings provide strong evidence that the identified coherent structures are directly related to the logarithmic velocity law and serve as the structural basis for the inertial layer.
Consensus sequence design as a general strategy to create hyperstable, biologically active proteins
Authors: Sternke Matt , Tripp Katherine W. , Barrick Doug
Published: May 2019

Significance

A major goal of protein design is to create proteins that have high stability and biological activity. Drawing on evolutionary information encoded within extant protein sequences, consensus sequence design has produced several successes in achieving this goal. Here, we explore the generality with which consensus design can be used to enhance protein stability and maintain biological activity. By designing and characterizing consensus sequences for six unrelated protein families, we find that consensus design shows high success rates in creating well-folded, hyperstable proteins that retain biological activities. Remarkably, many of these consensus proteins show higher stabilities than naturally occurring sequences of their respective protein families. Our study highlights the utility of consensus sequence design and informs the mechanisms by which it works.
Negative emotional contagion and cognitive bias in common ravens (
Corvus corax
)
Authors: Adriaense Jessie E. C. , Martin Jordan S. , Schiestl Martina , Lamm Claus , Bugnyar Thomas
Published: May 2019

Significance

To successfully and efficiently live in social groups, we need information about each other’s emotions. Emotional contagion has been suggested to facilitate such information transmission, yet it remains difficult to measure this in animals. Previous research has often focused on overt behavior but lacked additional methods for investigating emotional valence. This study provides a solution by integrating data on behavior and responses to a cognitive bias test, which is designed to infer a subject’s underlying emotional state. We demonstrate that after witnessing a conspecific in a negative state, ravens perform in a negatively biased manner on a judgment task. Our findings thus suggest negative emotional contagion in ravens, and in turn advance our understanding of the evolution of empathy.
Role of sociality in the response of killer whales to an additive mortality event
Authors: Busson Marine , Authier Matthieu , Barbraud Christophe , Tixier Paul , Reisinger Ryan R. , Janc Anaïs , Guinet Christophe
Published: May 2019

In highly social top predators, group living is an ecological strategy that enhances individual fitness, primarily through increased foraging success. Additive mortality events across multiple social groups in populations may affect the social structure, and therefore the fitness, of surviving individuals. This hypothesis was examined in a killer whale (Orcinus orca) population that experienced a 7-y period of severe additive mortality due to lethal interactions with illegal fishing vessels. Using both social and demographic analyses conducted on a unique long-term dataset encompassing periods before, during, and after this event, results indicated a decrease in both the number and the mean strength of associations of surviving individuals during the additive mortality period. A positive significant correlation between association strength and apparent survival suggested that the fitness of surviving individuals was impacted by the additive mortality event. After this event, individuals responded to the loss of relatives in their social groups by associating with a greater number of other social groups, likely to maintain a functional group size that maximized their foraging success. However, these associations were loose; individuals did not reassociate in highly stable social groups, and their survival remained low years after the mortality event. These findings demonstrate how the disruption of social structure in killer whales may lead to prolonged negative effects of demographic stress beyond an additive mortality event. More importantly, this study shows that sociality has a key role in the resilience of populations to human-induced mortality; this has major implications for the conservation of highly social and long-lived species.
Interrogating dense ligand chemical space with a forward-synthetic library
Authors: Chevillard Florent , Stotani Silvia , Karawajczyk Anna , Hristeva Stanimira , Pardon Els , Steyaert Jan , Tzalis Dimitrios , Kolb Peter
Published: May 2019

Significance

Virtual chemical space, i.e., the set of all conceivable drug-sized molecules, offers an abundance of unexplored quadrants which might contain novel bioactive compounds. Exploring these quadrants has to balance novelty of compounds with their synthetic accessibility. Forward-synthetic databases create novel chemical matter by combining existing and readily available building blocks, thereby biasing the resulting products toward synthesizability. To date, no one has tested whether molecules from such databases can be made in large numbers with an acceptable probability, and we investigated this question here. Moreover, we analyze whether the emerging molecules are binding to a G protein-coupled receptor (GPCR) target and whether ligands can be considered novel in the sense that they represent chemotypes which have not been described for this target before.
Estrogen receptor signaling is reprogrammed during breast tumorigenesis
Authors: Chi David , Singhal Hari , Li Lewyn , Xiao Tengfei , Liu Weihan , Pun Matthew , Jeselsohn Rinath , He Housheng , Lim Elgene , Vadhi Raga , Rao Prakash , Long Henry , Garber Judy , Brown Myles
Published: May 2019

Limited knowledge of the changes in estrogen receptor (ER) signaling during the transformation of the normal mammary gland to breast cancer hinders the development of effective prevention and treatment strategies. Differences in estrogen signaling between normal human primary breast epithelial cells and primary breast tumors obtained immediately following surgical excision were explored. Transcriptional profiling of normal ER
+
mature luminal mammary epithelial cells and ER
+
breast tumors revealed significant difference in the response to estrogen stimulation. Consistent with these differences in gene expression, the normal and tumor ER cistromes were distinct and sufficient to segregate normal breast tissues from breast tumors. The selective enrichment of the DNA binding motif GRHL2 in the breast cancer-specific ER cistrome suggests that it may play a role in the differential function of ER in breast cancer. Depletion of GRHL2 resulted in altered ER binding and differential transcriptional responses to estrogen stimulation. Furthermore, GRHL2 was demonstrated to be essential for estrogen-stimulated proliferation of ER
+
breast cancer cells. DLC1 was also identified as an estrogen-induced tumor suppressor in the normal mammary gland with decreased expression in breast cancer. In clinical cohorts, loss of DLC1 and gain of GRHL2 expression are associated with ER
+
breast cancer and are independently predictive for worse survival. This study suggests that normal ER signaling is lost and tumor-specific ER signaling is gained during breast tumorigenesis. Unraveling these changes in ER signaling during breast cancer progression should aid the development of more effective prevention strategies and targeted therapeutics.
Untangling the formation and liberation of water in the lunar regolith
Authors: Zhu Cheng , Crandall Parker B. , Gillis-Davis Jeffrey J. , Ishii Hope A. , Bradley John P. , Corley Laura M. , Kaiser Ralf I.
Published: May 2019

Significance

Observational evidence collected over the past two decades supports the existence of water on the Moon. However, the sources and chemical and/or physical processes responsible for the production of the lunar water are still unknown. Here, we provide evidence via laboratory simulation experiments that water can be generated and liberated through thermal shocks induced by micrometeorite impacts on solar-wind proton-implanted anhydrous silicates. Our findings are of fundamental importance for explaining the origin of water on the Moon as well as on other airless bodies such as Ceres and for untangling the present distribution of water in our solar system.
Organic–mineral interfacial chemistry drives heterogeneous nucleation of Sr-rich (Ba

x

, Sr

1−
x

)SO
4
from undersaturated solution
Authors: Deng Ning , Stack Andrew G. , Weber Juliane , Cao Bo , De Yoreo James J. , Hu Yandi
Published: May 2019

Significance

The wide occurrence of Sr-rich marine barite in undersaturated seawater presents a paradox. Here, in undersaturated solution, we observe barite nucleation on organic films and show it is enabled by cation enrichment. In supersaturated solution, this enrichment generates nanometer-sized Sr-rich nuclei on organic films, while Sr-poor barite grows quickly to micrometer-sized crystals in bulk solutions. Theoretical solid-solution calculations explain the distinct Sr incorporation in barites on organic films and in bulk solutions. The findings resolve the barite paradox and provide insights into manipulating solid-solution nucleation and growth through the unique chemical environment near organic–mineral interfaces, which may revise our understanding of many biomineralization processes and allow strategies for tailoring material synthesis to achieve desired sizes and compositions.
Assembly of the complexes of oxidative phosphorylation triggers the remodeling of cardiolipin
Authors: Xu Yang , Anjaneyulu Murari , Donelian Alec , Yu Wenxi , Greenberg Miriam L. , Ren Mindong , Owusu-Ansah Edward , Schlame Michael
Published: May 2019

Significance

Mitochondria contain cardiolipin, a special phospholipid that strongly interacts with proteins. Cardiolipin has a unique fatty acid composition, the disturbance of which causes the human disease Barth syndrome. However, neither the mechanism by which cardiolipin acquires specific fatty acids nor their actual function has been established. In this paper, we demonstrate that the expression of the complexes of oxidative phosphorylation is responsible for inducing the specific fatty acid composition in cardiolipin. We hypothesize that the purpose of this process is the stabilization of lipid–protein interactions in the extremely crowded environment of mitochondrial membranes.
Superconductivity in a unique type of copper oxide
Authors: Li W. M. , Zhao J. F. , Cao L. P. , Hu Z. , Huang Q. Z. , Wang X. C. , Liu Y. , Zhao G. Q. , Zhang J. , Liu Q. Q. , Yu R. Z. , Long Y. W. , Wu H. , Lin H. J. , Chen C. T. , Li Z. , Gong Z. Z. , Guguchia Z. , Kim J. S. , Stewart G. R. , Uemura Y. J. , Uchida S. , Jin C. Q.
Published: May 2019

Significance

Superconductivity is one of the most mysterious phenomena in nature in that the materials can conduct electrical current without any resistance. The cuprates hold the record high superconducting temperature at room pressure so far, but understanding their superconducting mechanism remains one of the big challenges. Here, we report high-
T

c

superconductivity in Ba
2
CuO

4-
y

with two unique features: an exceptionally compressed local octahedron and heavily overdoped hole carriers. These two features are in sharp contrast to the favorable criteria for all previously known cuprate superconductors. Thus, the discovery of high-
T

c

superconductivity in Ba
2
CuO

4-
y

calls into question the widely accepted scenario of superconductivity in the cuprates. This discovery provides a direction to search for additional high-
T

c

superconductors.
Muscle development and regeneration controlled by AUF1-mediated stage-specific degradation of fate-determining checkpoint mRNAs
Authors: Abbadi Dounia , Yang Ming , Chenette Devon M. , Andrews John J. , Schneider Robert J.
Published: May 2019

Significance

Muscle-wasting diseases are due in part to improper regulation of mRNA stability. Mutations in the mRNA decay protein AUF1 are linked to a specific form of muscle-wasting disease known as limb girdle muscular dystrophy that affects the muscles of the limbs and torso. How AUF1 is involved in regulating or promoting muscle regeneration is largely unknown. Here, we demonstrate that AUF1 controls all of the major stages of muscle development and regeneration, from control of the muscle stem (satellite) cell differentiation program through the development of mature muscle fibers, by selectively targeting for rapid degradation the major differentiation checkpoint mRNAs that block entry into each next phase of muscle development, thereby promoting each stage of muscle development.
MmpL3 is a lipid transporter that binds trehalose monomycolate and phosphatidylethanolamine
Authors: Su Chih-Chia , Klenotic Philip A. , Bolla Jani Reddy , Purdy Georgiana E. , Robinson Carol V. , Yu Edward W.
Published: May 2019

The cell envelope ofMycobacterium tuberculosisis notable for the abundance of mycolic acids (MAs), essential to mycobacterial viability, and of other species-specific lipids. The mycobacterial cell envelope is extremely hydrophobic, which contributes to virulence and antibiotic resistance. However, exactly how fatty acids and lipidic elements are transported across the cell envelope for cell-wall biosynthesis is unclear. Mycobacterial membrane protein Large 3 (MmpL3) is essential and required for transport of trehalose monomycolates (TMMs), precursors of MA-containing trehalose dimycolates (TDM) and mycolyl arabinogalactan peptidoglycan, but the exact function of MmpL3 remains elusive. Here, we report a crystal structure ofMycobacterium smegmatisMmpL3 at a resolution of 2.59 Å, revealing a monomeric molecule that is structurally distinct from all known bacterial membrane proteins. A previously unknown MmpL3 ligand, phosphatidylethanolamine (PE), was discovered inside this transporter. We also show, via native mass spectrometry, that MmpL3 specifically binds both TMM and PE, but not TDM, in the micromolar range. These observations provide insight into the function of MmpL3 and suggest a possible role for this protein in shuttling a variety of lipids to strengthen the mycobacterial cell wall.
Evolution of interlayer and intralayer magnetism in three atomically thin chromium trihalides
Authors: Kim Hyun Ho , Yang Bowen , Li Siwen , Jiang Shengwei , Jin Chenhao , Tao Zui , Nichols George , Sfigakis Francois , Zhong Shazhou , Li Chenghe , Tian Shangjie , Cory David G. , Miao Guo-Xing , Shan Jie , Mak Kin Fai , Lei Hechang , Sun Kai , Zhao Liuyan , Tsen Adam W.
Published: May 2019

Significance

Two-dimensional magnetic semiconductors such as CrI
3
are a new class of van der Waals material that may allow for the development of novel 2D spintronic devices. While strong magnetic anisotropy within the CrI
3
layers stabilizes ferromagnetism down to a monolayer, weak antiferromagnetic coupling between the layers gives rise to extremely large tunnel magnetoresistance. We use a combination of tunneling and magneto-optical measurements to investigate the entire 2D chromium trihalide family (CrX
3
, X = I, Br, Cl). Our results elucidate both the interlayer coupling and intralayer spin Hamiltonian for all three materials, and further demonstrate that ferromagnetism can be stabilized in monolayer CrBr
3
and bilayer CrCl
3
without strong anisotropy.
NURR1 activation in skeletal muscle controls systemic energy homeostasis
Authors: Amoasii Leonela , Sanchez-Ortiz Efrain , Fujikawa Teppei , Elmquist Joel K. , Bassel-Duby Rhonda , Olson Eric N.
Published: May 2019

Skeletal muscle plays a central role in the control of metabolism and exercise tolerance. Analysis of muscle enhancers activated after exercise in mice revealed the orphan nuclear receptor NURR1/NR4A2 as a prominent component of exercise-responsive enhancers. We show that exercise enhances the expression of NURR1, and transgenic overexpression of NURR1 in skeletal muscle enhances physical performance in mice. NURR1 expression in skeletal muscle is also sufficient to prevent hyperglycemia and hepatic steatosis, by enhancing muscle glucose uptake and storage as glycogen. Furthermore, treatment of obese mice with putative NURR1 agonists increases energy expenditure, improves glucose tolerance, and confers a lean phenotype, mimicking the effects of exercise. These findings identify a key role for NURR1 in governance of skeletal muscle glucose metabolism, and reveal a transcriptional link between exercise and metabolism. Our findings also identify NURR1 agonists as possible exercise mimetics with the potential to ameliorate obesity and other metabolic abnormalities.
Jensen polynomials for the Riemann zeta function and other sequences
Authors: Griffin Michael , Ono Ken , Rolen Larry , Zagier Don
Published: May 2019

Significance

The Pólya–Jensen criterion for the Riemann hypothesis asserts thatRHis equivalent to the hyperbolicity of certain Jensen polynomials for all degreesd≥1and all shiftsn. For each degreed≥1,we confirm this criterion for all sufficiently large shiftsn. This represents a theoretical advance in the field. The method of proof is rooted in the newly discovered phenomenon that these polynomials are nicely approximated by Hermite polynomials. Furthermore, it is shown that this method applies to a large class of related problems.
Microbial biospherics: The experimental study of ecosystem function and evolution
Authors: Rillig Matthias C. , Antonovics Janis
Published: May 2019

Awareness that our planet is a self-supporting biosphere with sunlight as its major source of energy for life has resulted in a long-term historical fascination with the workings of self-supporting ecological systems. However, the studies of such systems have never entered the canon of ecological or evolutionary tools and instead, have led a fringe existence connected to life support system engineering and space travel. We here introduce a framework for a renaissance in biospherics based on the study of matter-closed, energy-open ecosystems at a microbial level (microbial biospherics). Recent progress in genomics, robotics, and sensor technology makes the study of closed systems now much more tractable than in the past, and we argue that the time has come to emancipate the study of closed systems from this fringe context and bring them into a mainstream approach for studying ecosystem processes. By permitting highly replicated long-term studies, especially on predetermined and simplified systems, microbial biospheres offer the opportunity to test and develop strong hypotheses about ecosystem function and the ecological and evolutionary determinants of long-term system failure or persistence. Unlike many sciences, ecosystem ecology has never fully embraced a reductionist approach and has remained focused on the natural world in all its complexity. We argue that a reductionist approach to ecosystem ecology, using microbial biospheres, based on a combination of theory and the replicated study of much simpler self-enclosed microsystems could pay huge dividends.
Aberrant expression of select piRNA-pathway genes does not reactivate piRNA silencing in cancer cells
Authors: Genzor Pavol , Cordts Seth C. , Bokil Neha V. , Haase Astrid D.
Published: May 2019

Germline genes that are aberrantly expressed in nongermline cancer cells have the potential to be ideal targets for diagnosis and therapy due to their restricted physiological expression, their broad reactivation in various cancer types, and their immunogenic properties. Among such cancer/testis genes, components of the PIWI-interacting small RNA (piRNA) pathway are of particular interest, as they control mobile genetic elements (transposons) in germ cells and thus hold great potential to counteract genome instability in cancer. Here, we systematically investigate the potential reactivation of functional piRNA-silencing mechanisms in the aberrant context. While we observe expression of individual piRNA-pathway genes in cancer, we fail to detect the formation of functional piRNA-silencing complexes. Accordingly, the expression of a PIWI protein alone remains inconsequential to the cancer cell transcriptome. Our data provide a framework for the investigation of complex aberrant gene-expression signatures and establish that reactivation of piRNA silencing, if at all, is not a prevalent phenomenon in cancer cells.
Cardiac myosin activation with 2-deoxy-ATP via increased electrostatic interactions with actin
Authors: Powers Joseph D. , Yuan Chen-Ching , McCabe Kimberly J. , Murray Jason D. , Childers Matthew Carter , Flint Galina V. , Moussavi-Harami Farid , Mohran Saffie , Castillo Romi , Zuzek Carla , Ma Weikang , Daggett Valerie , McCulloch Andrew D. , Irving Thomas C. , Regnier Michael
Published: May 2019

Significance

The development of several small-molecule myosin activators to rescue cardiac contractility of failing hearts is underway, but understanding the multiscale structure-function consequences of these inotropes remains a major challenge. Using 2′-deoxy-adenosine 5′-triphosphate (dATP; a myosin-binding nucleotide) as a molecular probe, we show that a restructuring of prepowerstroke myosin in the presence of 2-deoxy-adenosine 5′-diphosphate and inorganic phosphate (dADP.Pi) (versus ADP.Pi) increases actin–myosin electrostatic interactions and binding kinetics. X-ray diffraction revealed myosin structure with dATP in relaxed myofilament is similar to the activated state with ATP, with S1 head movement toward actin and stabilization, resulting in an improved probability of strong cross-bridge formation upon activation. Thus, the alterations induced by dATP may provide clues to a more optimal structure of cardiac myosin to be attained by myosin-targeted therapies for heart failure.