bluuebunny/crossref_metadata_2025 huggingface dataset:
A critical state model for estimating the parameters of explosive emission plasmas
Authors: Tsventoukh M. M.
Published: February 2021

The parameters of the cathode spot plasma produced by explosive electron emission pulses have been estimated from the critical state properties for various materials. The kinetic energy of the cathode plasma flare has been estimated as 100 Tcr, where Tcr is the critical temperature of the cathode material. Based on a Saha-like equation and a two-temperature simulation of the explosion of a liquid-metal microjet, an estimation formula for the average ion charge has been derived, Zav = 1 + Tcr/eV, which fits the available experimental data. This has made it possible to explain the linear relationship between average charge and kinetic energy obtained experimentally for the cathode plasma ions. Using this formula, the previously derived expression for the plasma momentum per transferred charge μ has been simplified to become μ ∼5 (Mi/Mp)1/2 g cm/(s C), where Mi/Mp is the ion-to-proton mass ratio.
Transferability of machine learning potentials: Protonated water neural network potential applied to the protonated water hexamer
Authors: Schran Christoph , Brieuc Fabien , Marx Dominik
Published: February 2021

A previously published neural network potential for the description of protonated water clusters up to the protonated water tetramer, H+(H2O)4, at an essentially converged coupled cluster accuracy [C. Schran, J. Behler, and D. Marx, J. Chem. Theory Comput. 16, 88 (2020)] is applied to the protonated water hexamer, H+(H2O)6—a system that the neural network has never seen before. Although being in the extrapolation regime, it is shown that the potential not only allows for quantum simulations from ultra-low temperatures ∼1 K up to 300 K but is also able to describe the new system very accurately compared to explicit coupled cluster calculations. This transferability of the model is rationalized by the similarity of the atomic environments encountered for the larger cluster compared to the environments in the training set of the model. Compared to the interpolation regime, the quality of the model is reduced by roughly one order of magnitude, but most of the difference to the coupled cluster reference comes from global shifts of the potential energy surface, while local energy fluctuations are well recovered. These results suggest that the application of neural network potentials in extrapolation regimes can provide useful results and might be more general than usually thought.
Describing polymer polarizability with localized orbital scaling correction in density functional theory
Authors: Mei Yuncai , Yang Nathan , Yang Weitao
Published: February 2021

Polarizability reflects the response of the molecular charge distribution to an applied external electric field and thus closely relates to the molecular electron density. For the calculation of polarizability within density functional theory (DFT), it is well known that conventional density functional approximations (DFAs) greatly overestimate the results for polymers with long chains and the π-conjugated system. This is a manifestation of the delocalization error of the commonly used DFAs—they normally produce too delocalized electron density and underestimate the total energy for systems with fractional charge character, which occurs for long molecules in a longitudinal electric field. Thus, to achieve an accurate description of polarizabilities for polymeric molecular systems from DFT, applying DFAs with minimal delocalization error is very important. In this work, we use the recently developed localized orbital scaling correction (LOSC) to the conventional DFAs, which has been shown to largely eliminate the delocalization error, to calculate and study the polarizabilities of three classic polymers, polyyne, polyacetylene, and hydrogen chain. The results from this work demonstrate that applying LOSC to conventional DFAs with self-consistent field calculations can largely improve the description of polarizability from DFT calculations and the improved quality of electron density in LOSC leads to the improved results of polarizability of the polymers. However, the improvement is not complete and adjustment of the parameters in the LOSC method can further improve the accuracy to reach the level similar to the MP2 method. This work also points to the direction for the further development of LOSC in self-consistent calculations.
Understanding the impacts of cellular environments on ligand binding of membrane receptors by computational simulations
Authors: Su Zhaoqian , Dhusia Kalyani , Wu Yinghao
Published: February 2021

Binding of cell surface receptors with their extracellular ligands initiates various intracellular signaling pathways. However, our understanding of the cellular functions of these receptors is very limited due to the fact that in vivo binding between ligands and receptors has only been successfully measured in a very small number of cases. In living cells, receptors are anchored on surfaces of the plasma membrane, which undergoes thermal undulations. Moreover, it has been observed in various systems that receptors can be organized into oligomers prior to ligand binding. It is not well understood how these cellular factors play roles in regulating the dynamics of ligand–receptor interactions. Here, we tackled these problems by using a coarse-grained kinetic Monte Carlo simulation method. Using this method, we demonstrated that the membrane undulations cause a negative effect on ligand–receptor interactions. We further found that the preassembly of membrane receptors on the cell surface can not only accelerate the kinetics of ligand binding but also reduce the noises during the process. In general, our study highlights the importance of membrane environments in regulating the function of membrane receptors in cells. The simulation method can be potentially applied to specific receptor systems involved in cell signaling.
Role of the phonon confinement effect and boundary scattering in reducing the thermal conductivity of argon nanowire
Authors: Tretiakov Konstantin V. , Hyżorek Krzysztof
Published: February 2021

The thermal conductivity of model argon nanowires over a wide range of temperatures from 20 K to 70 K has been calculated using the formula obtained by solving the Boltzmann equation and independently by molecular dynamic (MD) simulations. The theoretical predictions for thermal conductivity take into account the effect of phonon confinement and boundary scattering. Two known theoretical approaches were used. The first approach is based on the solution of the Boltzmann equation with given boundary conditions and uses bulk acoustic phonon dispersion and neglects the phonon confinement effect. The second approach includes also the modification of acoustic phonon dispersion due to spatial confinement. In simulations, the square and circular shapes of wire with the transverse size of nanowires from 4.3 nm to 42.9 nm have been considered. It was found that MD simulation results match the theoretical predictions reasonably well. The obtained results showed that the phonon confinement effect influences the thermal conductivity of nanowires, but the dominant factor decreasing the thermal conductivity with the thickness of nanowires is boundary scattering. Moreover, the values of the interface specular parameter indicate that the specular phonon-boundary scattering prevails over diffuse phonon-boundary scattering.
Visualizing lattice dynamic behavior by acquiring a single time-resolved MeV diffraction image
Authors: Yang Xi , Tao Jing , Wan Weishi , Wu Lijun , Smaluk Victor , Shaftan Timur , Zhu Yimei
Published: February 2021

We explore the possibility of visualizing the lattice dynamics behavior by acquiring a single time-resolved mega-electron-volt ultrafast electron diffraction (UED) image. Conventionally, multiple UED shots with varying time delays are needed to map out the entire dynamic process. The measurement precision is limited by the timing jitter between the pulses of the pump laser and the electron probe, the intensity fluctuation of probe pulses, and the premature sample damage. Inspired by the early transient spectroscopy studies via an ultrashort-pulse pump/long-pulse probe scheme, we show that, by converting the longitudinal time of an electron pulse to the transverse position of a Bragg peak on the detector, one can obtain the full lattice dynamic process in a single electron pulse. This time-to-position mapping can be achieved by the combination of longitudinally shaping the electron beam and introducing a time-dependent transverse kick after electrons are diffracted from the sample. We propose a novel design of time-resolved UED facility with the capability of capturing a wide range of dynamic features in a single diffraction image. To achieve the best possible temporal resolution, we implement a real-time tuning scheme for optimizing the match between the electron bunch length and the lattice dynamic timescale, varying in the sub-picosecond to tens of picosecond (ps) range depending on the specific process. This timescale match is in favor of the ultrafast phenomenon, which requires a 10 fs temporal resolution for resolving the sub-ps oscillation. A state-of-the-art photocathode gun being developed by Euclid could extend the timescale to hundreds of ps. To study the radiation damage and to mitigate such effect, longitudinally shaping the photocathode drive laser pulse (demonstrated in a previous study) can control and manipulate the electron beam current profile with a tunable periodical structure. Furthermore, we present numerical evidence illustrating the capability of acquiring a single time-resolved diffraction image based on the case-by-case studies of different lattice dynamics behaviors.
Using machine-learning modeling to understand macroscopic dynamics in a system of coupled maps
Authors: Borra Francesco , Baldovin Marco
Published: February 2021

Machine-learning techniques not only offer efficient tools for modeling dynamical systems from data but can also be employed as frontline investigative instruments for the underlying physics. Nontrivial information about the original dynamics, which would otherwise require sophisticated ad hoc techniques, can be obtained by a careful usage of such methods. To illustrate this point, we consider as a case study the macroscopic motion emerging from a system of globally coupled maps. We build a coarse-grained Markov process for the macroscopic dynamics both with a machine-learning approach and with a direct numerical computation of the transition probability of the coarse-grained process, and we compare the outcomes of the two analyses. Our purpose is twofold: on the one hand, we want to test the ability of the stochastic machine-learning approach to describe nontrivial evolution laws as the one considered in our study. On the other hand, we aim to gain some insight into the physics of the macroscopic dynamics. By modulating the information available to the network, we are able to infer important information about the effective dimension of the attractor, the persistence of memory effects, and the multiscale structure of the dynamics.
A purely kinetic description of the evaporation of water droplets
Authors: Houle Frances A. , Miles Rachael E. H. , Pollak Connor J. , Reid Jonathan P.
Published: February 2021

The process of water evaporation, although deeply studied, does not enjoy a kinetic description that captures known physics and can be integrated with other detailed processes such as drying of catalytic membranes embedded in vapor-fed devices and chemical reactions in aerosol whose volumes are changing dynamically. In this work, we present a simple, three-step kinetic model for water evaporation that is based on theory and validated by using well-established thermodynamic models of droplet size as a function of time, temperature, and relative humidity as well as data from time-resolved measurements of evaporating droplet size. The kinetic mechanism for evaporation is a combination of two limiting processes occurring in the highly dynamic liquid–vapor interfacial region: direct first order desorption of a single water molecule and desorption resulting from a local fluctuation, described using third order kinetics. The model reproduces data over a range of relative humidities and temperatures only if the interface that separates bulk water from gas phase water has a finite width, consistent with previous experimental and theoretical studies. The influence of droplet cooling during rapid evaporation on the kinetics is discussed; discrepancies between the various models point to the need for additional experimental data to identify their origin.
Thermal stability and gas absorption characteristics of ionic liquid-based solid polymer electrolytes
Authors: Shirani Asghar , Lee Jihung , Berman Diana
Published: February 2021

Ionic liquid (IL)-based solid polymer electrolytes (SPE) with stable thermal properties and low electrical resistivity have been evaluated. Two candidates for the polymer component of the SPE, poly(ethylene glycol) diacrylate (PEGDA) and Nafion, were considered. Differential scanning calorimetry analysis and electrical resistivity tests revealed that PEGDA, in comparison to Nafion, enables the formation of uniform SPEs with lower electrical resistivity and better thermal stability within a range of 25 °C–170 °C. Therefore, PEDGA was selected for further evaluation of the IL component effect on the resulting SPE. Six IL candidates, including 1-butyl-3-methylimidazolium methanesulfonate ± methanesulfonic acid (BMIM.MS ± MSA), diethylmethylammonium triflate ±bis(trifluoromethanesulfonyl)imine (Dema.OTF±HTFSI), and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ± bis(trifluoromethanesulfonyl)imine (BMIM.TFSI ± HTFSI), were selected to test the effect of hydrophobicity/hydrophilicity of the IL on the resulting SPE. Fourier transformation infrared spectrometer analysis revealed that the BMIM.MSA-based electrolytes have the highest tendency to absorb from the environment and keep the moisture, while Dema.OTF has the fastest curing time. The SPE candidates were further evaluated for absorption characteristics of different gasses and vapors, such as N2, O2, ethanol vapor, and diluted CO/N2, that were tested with the in situ quartz crystal microbalance (QCM) technique. Among all six candidates, BMIM.MS showed the largest N2 and O2 absorption capacity from the environment. Dema.OTF + HTFSI, meanwhile, demonstrated a higher level of interactions with the ethanol vapor. In the case of CO/N2, QCM analysis revealed that BMIM.MS+MSA has the largest, ∼13 µg/cm2, absorption capacity that is reached within 400 s of being exposed to the gas mixture.
Clustering of oxygen point defects in transition metal nitrides
Authors: Kumar Rajendra , Nayak Sanjay , Garbrecht Magnus , Bhatia Vijay , Indiradevi Kamalasanan Pillai Ashalatha , Gupta Mukul , Shivaprasad S. M. , Saha Bivas
Published: February 2021

Point defects create exotic properties in materials such as defect-induced luminescence in wide-bandgap semiconductors, magnetism in nonmagnetic materials, single-photon emission from semiconductors, etc. In this article, oxygen defect formation in metallic TiN and semiconducting rock salt-(Al,Sc)N is investigated with a combination of first-principles density functional theory, synchrotron-based x-ray absorption spectroscopy (XAS) analysis, and scanning transmission electron microscopy–energy-dispersive x-ray spectroscopy mapping. Modeling results show that oxygen in TiN and rock salt-(Al,Sc)N prefers to be in the defect complex of substitutional and interstitial oxygen (nON + Oi) types. While in TiN, the preferential interstitial sites of oxygen in ON + Oi are at the tetrahedral site, in rock salt-(Al,Sc)N, a split interstitial site along the [111] direction was found to be energetically preferable. Simulations performed as a function of the oxygen partial pressure show that under experimental growth conditions, four oxygen atoms at the substitutional sites of nitrogen (4ON), along with four Ti atoms, decorate around an interstitial oxygen atom at the tetrahedral site (Oi) in the energetically favored configuration. However, in rock salt-(Al,Sc)N, n in nON + Oi was found to vary from two to four depending on the oxygen partial pressure. Theoretical predictions agree well with the experimentally obtained XAS results. These results are not only important for a fundamental understanding of oxygen impurity defect behavior in rock salt nitride materials but will also help in the development of epitaxial metal/semiconductor superlattices with efficient thermionic properties.
Modeling the current modulation of bundled DNA structures in nanopores
Authors: Szuttor Kai , Weik Florian , Grad Jean-Noël , Holm Christian
Published: February 2021

We investigate the salt-dependent current modulation of bundled DNA nanostructures in a nanopore. To this end, we developed four simulation models for a 2 × 2 origami structure with increasing level of detail ranging from the mean-field level to an all-atom representation of the DNA structure. We observe a consistent pore conductivity as a function of salt concentration for all four models. However, a comparison of our data to recent experimental investigations on similar systems displays significant deviations. We discuss possible reasons for the discrepancies and propose extensions to our models for future investigations.
Collision dominated, ballistic, and viscous regimes of terahertz plasmonic detection by graphene
Authors: Zhang Yuhui , Shur Michael S.
Published: February 2021

The terahertz detection performance and operating regimes of graphene plasmonic field-effect transistors (FETs) were investigated by a hydrodynamic model. Continuous wave detection simulations showed that the graphene response sensitivity is similar to that of other materials including Si, InGaAs, GaN, and diamond-based FETs. However, the pulse detection results indicated a very short response time, which favors rapid/high-sensitively detection. The analysis on the mobility dependence of the response time revealed the same detection regimes as the traditional semiconductor materials, i.e., the non-resonant (collision dominated) regime, the resonant ballistic regime, and the viscous regime. When the kinematic viscosity (ν) is above a certain critical viscosity value, νNR, the plasmonic FETs always operates in the viscous non-resonant regime, regardless of channel length (L). In this regime, the response time rises monotonically with the increase of L. When ν < νNR, the plasmonic resonance can be reached in a certain range of L (i.e., the resonant window). Within this window, the carrier transport is ballistic. For a sufficiently short channel, the graphene devices would always operate in the non-resonant regime, regardless of the field-effect mobility, corresponding to another viscous regime. The above work mapped the operating regimes of graphene plasmonic FETs and demonstrated the significance of the viscous effects for the graphene plasmonic detection. These results could be used for the extraction of the temperature dependences of viscosity in graphene.
Expanding the understanding of organic electrochemical transistor function
Authors: Nissa Josefin , Janson Per , Simon Daniel T. , Berggren Magnus
Published: February 2021

Organic electrochemical transistors (OECTs) have gained significant interest in recent years due to their ability to transduce and amplify biochemical signals into easily recorded electrical signals. The magnitude of the amplification offered by an OECT is proportional to its transconductance, gm, making gm an important figure of merit. Much attention has, therefore, been paid to the materials and device geometries, which can maximize an OECT's gm. However, less attention has been paid to the role of the applied potentials and various operational regimes. In this paper, we expand on the seminal Bernards and Malliaras model of the OECT function to include negative gate potentials, allowing prediction of gm and general biosensor performance over a broader application range. The expanded model results in five operational regimes, only two of which were covered by the original model. We find an optimal combination of drain and (negative) gate potentials yielding maximal gm. We also find that reducing the pinch-off potential well below the water-splitting limit can yield larger operational windows at the highest gm. Our expanded model presents a general set of guidelines for OECT operation, yielding the highest possible gm, and, therefore, optimal amplification and associated (bio)sensor performance.
Deep level transient spectroscopy characterization without the Arrhenius plot
Authors: Li Jian V.
Published: February 2021

Defect characterization by deep level transient spectroscopy (DLTS) requires the extraction of two key quantities of the carrier emission rate from the defects—activation energy (Ea) and pre-exponential factor (ν0)—the latter is related to the carrier capture cross section. This task, ubiquitous to thermally activated processes besides defect–carrier interaction, is traditionally accomplished by constructing an Arrhenius plot with DLTS peak locations and fitting it with a line. We present a transformation method based on the Arrhenius equation that extracts Ea and ν0 without constructing or line-fitting the Arrhenius plot and bypasses peak identification. This method is developed on the basis of the fundamental temperature-rate duality relationship and extracts Ea and ν0 by matching the curvatures the Arrhenius-transformed spectra of the iso-thermal and iso-rate DLTS scans in the 2D temperature-rate plane. The extraction can be conducted with data in a small temperature range and is, therefore, capable of unambiguously resolving Ea and ν0 at any temperature point and their temperature dependence, if any.
Coulomb blockade in field electron emission from carbon nanotubes
Authors: Kleshch Victor I. , Porshyn Vitali , Serbun Pavel , Orekhov Anton S. , Ismagilov Rinat R. , Malykhin Sergey A. , Eremina Valentina A. , Obraztsov Petr A. , Obraztsova Elena D. , Lützenkirchen-Hecht Dirk
Published: February 2021

We report the observation of Coulomb blockade in electron field emission (FE) from single-wall carbon nanotubes (SWCNTs), which is manifested as pronounced steps in the FE current–voltage curves and oscillatory variations in the energy distribution of emitted electrons. The appearance of the Coulomb blockade is explained by the formation of nanoscale protrusions at the apexes of SWCNTs due to the electric field-assisted surface diffusion of adsorbates and carbon adatoms. The proposed adsorbate-assisted FE mechanism is substantially different from the well-known resonant tunneling associated with discrete electronic states of adsorbed atoms. The simulations based on the Coulomb blockade theory are in excellent agreement with the experimental results. The SWCNT field emitters controlled by the Coulomb blockade effect are expected to be used to develop on-demand coherent single-electron sources for advanced vacuum nanoelectronic devices.
Optically tunable all-silicon chiral metasurface in terahertz band
Authors: Zheng Chenglong , Li Jie , Wang Silei , Li Jitao , Li Mengyao , Zhao Hongliang , Hao Xuanruo , Zang Huaping , Zhang Yating , Yao Jianquan
Published: February 2021

The chiral optical response represents interactions of circularly polarized light with matter. Chiral metamaterials are widely applied in polarization imaging, optical sensing, and other fields due to their strong ability to manipulate light and form giant circular polarization differential transmittance (CPDT). Here, we propose all-silicon chiral metasurfaces for highly efficient CPDT in the terahertz band. In addition to characterizing the static chiral properties of our proposed metasurface, dynamic chiral behaviors are also characterized by optical pumping (1064 nm continuous wave), and a giant amplitude modulation depth is obtained. The measured results agree well with the simulations. In addition, the application of our chiral metasurface in polarization multiplexed near-field image display is also exhibited. Such chiral metasurface could find many potential applications in photon-spin selective devices, such as circularly polarized light detectors and chiral sensors.
Integrator based on current-controlled magnetic domain wall
Authors: Luo Shijiang , Tian Weicheng , Zhang Shuai , Li Ruofan , Min Run , Yang Xiaofei , Zou Xuecheng , Hong Jeongmin , You Long
Published: February 2021

Integrators are widely used in industrial controls, signal processing, and computing. However, traditional resistor–capacitor integrators incur leakage errors and zero drift, hindering their accuracy. By contrast, spintronic devices with good scalability and endurance for memory and logic applications in digital circuits have yet to be studied for analog circuit elements. Here, we propose a single-device spintronic integrator based on the current-controlled magnetic domain wall (DW). Continuous DW motion and correlated changes in the anomalous Hall resistance (or magneto-resistance) are encoded as an analog output signal, which is modulated by an input current through the spin–orbit-torque effect. Waveform transformation and phase-shift functions are demonstrated using Hall-bar devices. The spintronic integrator could pave the way for the spin-based analog computing with high reliability, high endurance, and good compatibility with the CMOS process.
Guiding inventions from lab to market
Authors: Feder Toni
Published: February 2021

A career in technology transfer requires skills in multitasking, communicating, and negotiating; one reward is seeing scientific advances benefit society.
Th2 cells lacking T-bet suppress naive and memory T cell responses via IL-10
Authors: Muñoz Melba , Hegazy Ahmed N. , Brunner Tobias M. , Holecska Vivien , Marek Roman M. , Fröhlich Anja , Löhning Max
Published: February 2021

Significance

Strategies to suppress memory T cell responses are needed. Th2-polarized cells lacking the transcription factor T-bet strongly suppress not only naive but also memory T cell responses via IL-10 and protect mice against the development of virus-induced type 1 diabetes. We shed light on a population of immune cells with substantial immunomodulatory capacity.
Conjugative plasmids interact with insertion sequences to shape the horizontal transfer of antimicrobial resistance genes
Authors: Che You , Yang Yu , Xu Xiaoqing , Břinda Karel , Polz Martin F. , Hanage William P. , Zhang Tong
Published: February 2021

Significance

There is great interest in understanding how antibiotic resistance is disseminated by MGEs (i.e., plasmids, insertion sequences, and integrons). We have systematically investigated their interactions in mediating the horizontal transfer of resistance by combining in silico genomic analysis of a large collection of complete bacterial plasmids (14,029) and genomes (12,059), and then confirmed the interactions we observe in nature using direct experimental approaches. We showed a whole picture of all the IS-associated transfer patterns of AMR genes across different genetic backgrounds and our results highlight the significant relationships between conjugative plasmids and ISs in shaping the dissemination of AMR genes.
High-resolution imaging reveals compartmentalization of mitochondrial protein synthesis in cultured human cells
Authors: Zorkau Matthew , Albus Christin A. , Berlinguer-Palmini Rolando , Chrzanowska-Lightowlers Zofia M. A. , Lightowlers Robert N.
Published: February 2021

Significance

In mitochondria from various species, the OXPHOS complexes reside mainly in the invaginated cristae membranes, as opposed to the inner boundary membrane (IBM) that parallels the mitochondrial outer membrane. However, the IBM contains dynamic contact sites enriched for translocases that import proteins from the cytosol. As the majority of OXPHOS components are imported and need to be integrated in assembly with the mtDNA-encoded components, where does intramitochondrial translation occur? Here we report: 1) a method for visualizing protein synthesis in human mitochondria at super resolution; 2) that synthesis is enriched at cristae membranes, in preference to the IBM; and 3) that sites of translation are spatially separated from RNA granules where RNA processing, maturation, and mitoribosomal assembly occur.
Area-specific thalamocortical synchronization underlies the transition from motor planning to execution
Authors: Nashef Abdulraheem , Mitelman Rea , Harel Ran , Joshua Mati , Prut Yifat
Published: February 2021

Significance

Thalamocortical interactions are a key component of normal brain functions both in sensory and motor areas. The fact that TC connectivity is excitatory has led to the suggestion that its main role is positively driving motor cortical activity. Here we show that the motor thalamus has contrasting, area-dependent interactions with cortical sites, such that it can either enhance or suppress motor cortical variability. The TC interactions with the primary motor vs. the premotor cortex put the motor thalamus in an ideal position to promote the transition from a motor plan to motor action and serve as an important driver of movement initiation.
The KRAS and other prenylated polybasic domain membrane anchors recognize phosphatidylserine acyl chain structure
Authors: Zhou Yong , Prakash Priyanka S. , Liang Hong , Gorfe Alemayehu A. , Hancock John F.
Published: February 2021

Significance

Electrostatics have been thought to dominate interactions between a polybasic membrane anchoring motif and anionic lipids in the plasma membrane. Combining data from computational and imaging techniques, here we show that distinct conformational dynamics and interaction patterns of prenylated polybasic domains encode specificity for lipid acyl chain saturation. This previously unrecognized capacity to distinguish between acyl chain structures renders the anchor sensitive to the biophysical properties of the membrane, which are in turn determined by the acyl chain structure of the composite lipids. We propose that lipid acyl chain structure and dynamics participate in the regulation of the spatial distribution of prenylated polybasic membrane anchors found in many membrane-bound small GTPases, and possibly polybasic domains in other membrane associated proteins.
Consequences of aneuploidy in human fibroblasts with trisomy 21
Authors: Hwang Sunyoung , Cavaliere Paola , Li Rui , Zhu Lihua Julie , Dephoure Noah , Torres Eduardo M.
Published: February 2021

Significance

An abnormal number of chromosomes or aneuploidy accounts for most spontaneous abortions, as missegregation of a single chromosome during development is often lethal. Only individuals with trisomy 21, which causes Down syndrome, can live to adulthood but show cognitive disabilities, increased risk for leukemias, autoimmune disorders, and clinical symptoms associated with premature aging. The mechanisms by which aneuploidy affects cellular function to cause Down syndrome are not understood. Our studies revealed that aneuploidy causes several defects in cells from individuals with Down syndrome. These include increased gene and protein expression, lower viability, and increased dependency on serine to proliferate. Our studies establish a critical role of aneuploidy, independent of triplicated gene identity, in driving cellular defects associated with trisomy 21.
The long-term effects of war exposure on civic engagement
Authors: Barceló Joan
Published: February 2021

What are the legacies of war exposure on civic engagement? Recent evidence suggests that domestic war may have short-term effects on participation in social organizations. Yet, it is unclear whether these effects will be present in internationalized conflicts and persist over long periods of time. Further, the pathways of persistence by which war exposure leads to greater civic engagement in the long term are even less understood. In this paper, I contribute to both questions using unique evidence from the Vietnam War. Empirically, I combine a unique US military dataset containing bombing intensity with respondents’ wartime place of residence to generate an objective indicator of conflict intensity. Then, I exploit the distance to the arbitrarily drawn border at the 17th parallel as an instrument for conflict intensity. The results show that individuals who lived in a province heavily affected by the conflict during the war tend to be more engaged in social organizations and hold greater expressive values, at least 26 y later. Further, I empirically explore the mechanisms of persistence. The empirical evidence suggests that both persistence within individuals and community-wide transmission jointly account for the long-term increase of civic engagement after conflict.
Histone H3Q5 serotonylation stabilizes H3K4 methylation and potentiates its readout
Authors: Zhao Shuai , Chuh Kelly N. , Zhang Baichao , Dul Barbara E. , Thompson Robert E. , Farrelly Lorna A. , Liu Xiaohui , Xu Ning , Xue Yi , Roeder Robert G. , Maze Ian , Muir Tom W. , Li Haitao
Published: February 2021

Significance

Histone H3Q5ser and H3K4me3 can coexist as a dual modification pattern to regulate active gene transcription. However, the molecular impact of H3Q5ser on H3K4me3 recognition and catalysis remains largely unexplored. Here, we profile the influence of H3Q5ser on H3K4 methylation readers, writers, and erasers. Interestingly, all tested H3K4me3 readers bind H3K4me3Q5ser. Furthermore, while the activity of the H3K4 methyltransferase, MLL1, is unaffected by H3Q5ser, corresponding H3K4 methylation erasers are profoundly inhibited by the presence of the mark. Collectively, this work suggests that H3Q5ser plays an augmenting role when coupled with the installation of H3K4 methylation so as to potentiate downstream outputs via chromatin readers and erasers. The present work exemplifies the importance of modification crosstalk in gene regulation.
Lactobacillus
bile salt hydrolase substrate specificity governs bacterial fitness and host colonization
Authors: Foley Matthew H. , O’Flaherty Sarah , Allen Garrison , Rivera Alissa J. , Stewart Allison K. , Barrangou Rodolphe , Theriot Casey M.
Published: February 2021

Significance

The transformation of bile acids (BAs) by the gut microbiota is increasingly recognized as an important factor shaping host health. The prerequisite step of BA metabolism is carried out by bile salt hydrolases (BSHs), which are encoded by select gut and probiotic bacteria. Despite their prevalence, the utility of harboring a
bsh
is unclear. Here, we investigate the role of BSHs encoded by
Lactobacillus acidophilus
and
Lactobacillus gasseri
. We show that BA type and BSH substrate preferences affect in vitro and in vivo growth of both species. These findings contribute to a mechanistic understanding of bacterial survival in various BA-rich niches and inform future efforts to leverage BSHs as a therapeutic tool for manipulating the gut microbiota.
Vertical sleeve gastrectomy confers metabolic improvements by reducing intestinal bile acids and lipid absorption in mice
Authors: Ding Lili , Zhang Eryun , Yang Qiaoling , Jin Lihua , Sousa Kyle M. , Dong Bingning , Wang Yangmeng , Tu Jui , Ma Xiaoxiao , Tian Jingyan , Zhang Hongli , Fang Zhipeng , Guan Ana , Zhang Yixin , Wang Zhengtao , Moore David D. , Yang Li , Huang Wendong
Published: February 2021

Significance

Vertical sleeve gastrectomy (VSG) is a highly effective bariatric surgery that sustainably treats obesity and type 2 diabetes (T2D). However, the underlying mechanisms governing its metabolic benefits remain unclear. In this study, we have used four different genetically modified mouse lines to understand the link between bile acid circulation and metabolic effects of VSG. Instead of directly activating the nuclear bile acid receptor farnesoid X receptor (Fxr) in the liver or intestine, VSG reduces intestinal levels of bile acids, thereby decreasing fat absorption in the intestine. Given the rising popularity of bariatric surgeries to treat obesity and associated T2D, the results described herein provide mechanistic insights that may lead to safer noninvasive approaches to mimic the metabolic effects of bariatric surgery.
Nonsurgical treatment of skin cancer with local delivery of bioadhesive nanoparticles
Authors: Hu Jamie K. , Suh Hee-Won , Qureshi Munibah , Lewis Julia M. , Yaqoob Sharon , Moscato Zoe M. , Griff Sofia , Lee Alison K. , Yin Emily S. , Saltzman W. Mark , Girardi Michael
Published: February 2021

Significance

One in five individuals in the United States will develop skin cancer over the course of a lifetime, and nonsurgical options are limited. To address this, we developed a bioadhesive nanoparticle (BNP) treatment for long-lasting local drug delivery. Incorporation of the topoisomerase inhibitor camptothecin (CPT) into BNPs enhanced tumor cell uptake, bioadhesion within the tumor microenvironment, and prolonged intratumoral drug retention. Therefore, we investigated BNPs encapsulating CPT as a local, nonsurgical treatment for nodular squamous cell carcinoma (SCC) skin cancers in a mouse model. BNP-CPT treatment facilitated tumor destruction and resolution, and was compatible with local immunotherapy. These findings suggest that BNP delivery of antitumor agents may provide opportunities for nonsurgical treatment of nodular skin cancers like SCC.
Genome-wide role of codon usage on transcription and identification of potential regulators
Authors: Zhao Fangzhou , Zhou Zhipeng , Dang Yunkun , Na Hyunsoo , Adam Catherine , Lipzen Anna , Ng Vivian , Grigoriev Igor V. , Liu Yi
Published: February 2021

Significance

Codon usage bias, the preference for certain synonymous codons, is a feature of all genomes and plays an important role in determining gene expression levels. Surprisingly, in addition to its role in mRNA translation, codon usage was recently shown to regulate gene expression at the transcriptional level. In this study, our results suggest that codon usage influences transcription genome-wide independently of its effect on translation. By carrying out a large-scale genetic screen, we identified 18 factors participating in multiple transcriptional regulatory mechanisms involved in the codon usage-mediated transcriptional effects. Together, our study establishes a foundation for future mechanistic understanding of this gene regulatory phenomenon.
The positioning of Japanese in a secondary CLIL science classroom in Australia
Authors: Turner Marianne
Published: February 2021

In Australia, content and language integrated learning (CLIL) is commonly implemented as a way to encourage
innovation in language teaching. This paper explores how Japanese can also be used to innovate the teaching of content.
Qualitative data are drawn from a Year 8 science Japanese CLIL classroom in a secondary school with an opt-in CLIL program. In the
class, a monolingual (in English) science teacher was co-teaching with a Japanese language teacher. Findings from observations,
after-class reflections, teacher and student interviews, a student survey and work samples revealed that students were highly
engaged with the Japanese component of their science lessons. Kanji was further positioned as a way for students to deepen their
understanding of scientific concepts. However, there also appeared to be a separation in the way both teachers and students spoke
about Japanese language use and learning science. Implications of these findings are discussed in the paper.
The interaction between timing of explicit grammar explanation and individual differences in second language
acquisition
Authors: Kachinske Ilina , DeKeyser Robert M.
Published: February 2021

Despite numerous positive findings of explicit instruction, this topic continues to engage scholars worldwide. One
issue that may be crucial for the effectiveness of explicit instruction is the interaction between cognitive individual
differences (language aptitude and working memory) and types of instruction. In this experiment, 128 learners of Spanish were
randomly assigned to four experimental treatments and completed comprehension-based practice for interpreting object-verb and
ser/estar sentences in Spanish. Results revealed that the various combinations of rules and practice posed differential task
demands on the learners and consequently drew on language aptitude and working memory to a different extent. We argue that not
only are rules and practice both necessary, but that their suitable integration ameliorates task demands, reducing the burden on
the learner, and accordingly mitigates the role of participants’ individual differences, thus making a substantial difference for
the learning of second language grammar.
Ethnolinguistic vitality and linguistic landscape
Authors: Pastor Alberto
Published: February 2021

Using a quantitative-method approach, a corpus of
photos of Linguistic Landscape texts taken in the most densely
populated Hispanic neighborhoods in Dallas (Texas) is analyzed in
search of indicators that allow us to gauge the ethnolinguistic
vitality of Spanish in the region. This research goal is
operationalized by studying the relative distribution of Spanish and
English in bilingual linguistic landscape texts; the symbolic and
informational meanings of each language; the representation of local
Spanish varieties, including phenomena related to language contact;
and the use or non-use of normative writing conventions. The
findings of this study augment our understanding of the impact of
existing language ideologies and attitudes towards local varieties
of Spanish on the prestige and utility of Spanish.
Urban discourse and civil resistance against gender-based
violence in Madrid
Authors: Molina Martos Isabel
Published: February 2021

Linguistic Landscape is analyzed to determine how
women’s voices come together in the urban space to ultimately become
a political movement. In recent years, women in Spain have been at
the front and center of an unprecedented mobilization against gender
inequality in all of its forms: salary gap, discrimination and
sexual violence, putting them at the leading edge of feminism
worldwide. I show how this political movement develops in Madrid. My
study is based on geosemiotics (Scollon & Scollon, 2003) and a qualitative
methodology is applied to understand how the social and political
action of protest is approached as mediated through texts and
signs.
Languages to buy and sell
Authors: Aijón Oliva Miguel A.
Published: February 2021

This chapter is concerned with linguistic
diversity in business names across the Spanish town of Salamanca.
Going from the urban center to the periphery, it examines three
areas that are relatively differentiated according to average
household income and immigrant population rate, among other
indicators. The analysis shows that the use of English and other
European languages is characteristic of the highly
commercially-oriented town center, while the most peripheral area
shows the emergence of Arabic and dialectal features of Latin
American Spanish, in line with recent migratory flows. Business
names in the intermediate area sometimes combine Spanish and English
features. The results are qualitatively interpreted as being
indexical of three different metaphorical directions of language
choice, namely outward, upward and
inward.
An analysis of how business owners use Valencian and Spanish in
the linguistic landscape
Authors: Martínez Ibarra Francisco
Published: February 2021

The study of the Linguistic Landscape provides
opportunities to ethnolinguistically depict a community. It also
allows for deciphering communication patterns among users and
understand societal perceptions of language use. This paper examines
the contact between Spanish and a western variety of Catalan (i.e.
Valencian) on the linguistic landscape produced by private business
owners in Elche, Spain. An analysis of data collected through
observation, personal interviews and written questionnaires suggests
the reader and potential customer appears to be the main driving
force behind language choice in the linguistic landscape of
Elche.
Cooling during short‐term heat acclimation enhances aerobic capacity but not sweat capacity
Authors: Naito Takashi , Haramura Miki , Muraishi Koji , Yamazaki Misa , Takahashi Hideyuki
Published: February 2021

To characterize the adaptive responses to short‐term heat acclimation (HA) training with repeated‐sprint exercises and to determine the effects of ice slurry ingestion during HA on aerobic capacity and adaptations. Seven physically active males completed two 5 consecutive day interventions in a randomized cross‐over design. Participants performed approximately 80‐min intermittent repeated‐sprints using a cycling ergometer including break‐time and half time in 36.5°C and 50%RH. Participants ingested either 1.25 g·kg body mass−1 of ice slurry (ICE: −1°C) or room temperature beverage (NOC: 36.5°C) throughout each break and 7.5 g·kg body mass−1 of the same drink during half time. Maximum oxygen uptake ( O2max) test in hot conditions was completed before and after HA training. Ice slurry ingestion during short‐term HA training induced significantly higher both O2max and watt at O2max following HA training. Total work done was significantly higher in HA with ICE than for the NOC trial on both day 1 and day 5. Sweating Na+ concentration in NOC trial at day 5 were significantly lower than those in the NOC trial day 1, but was not observed in ICE trial. Cooling during HA training may be an effective strategy for enhancement of aerobic capacity via the adaptations gained from a higher quantity of exercise caused by cooling, but does not improve heat loss capacity.

Highlights

There is the potential dilemma whether cooling during short‐term training in the heat might negatively impacts the process of helping athletes adapt to hot environments.

Cooling during short‐term heat training may be an effective strategy to enhancement of aerobic capacity via the adaptations gained from a higher quantity of exercise caused by cooling, but does not improve heat loss capacity.

The study suggests the importance to selecting cooling during the heat acclimation phase of consecutive field training according to the individual's training plan.
Small town, big risks: natural, cultural and social risk perception (Ciudad pequeña, grandes riesgos: percepción del riesgo natural, cultural y social)
Authors: Valente João-Pedro , Gouveia Catarina , Neves Maria-Carolina , Vasques Tatiana , Bernardo Fátima
Published: February 2021

Benavente (Portugal) is a small town which, compared to the rest of the country, has higher levels of the following three types of risks: earthquakes (natural risk), criminality (social risk) and the running of the bulls (cultural risk). This has allowed us to explore spatial bias, i.e., whether people have lower perceptions of risk at the local level than at the national or international levels, or if there are any risks strongly related with the local culture that show a different pattern. We also test whether risk perception dimensions identified by a psychometric paradigm relate to the three risk types that are highly prevalent in Benavente. The results support the spatial bias in relation to earthquakes and criminality but reveal a reverse pattern regarding the running of the bulls (cultural risk). The results also showed that people scored higher on the Dread dimension for earthquakes, followed by criminality, with lower scores in regard to the running of the bulls. The opposite was verified regarding the Control dimension.