bluuebunny/crossref_metadata_2025 huggingface dataset:
Donor–acceptor units modulate the electronic and photoluminescence characteristics of thiophene oligomers
Authors: Hu Ziyu , Zhang Shengli , Zhang Chunfang , Shao Xiaohong
Published: December 2019

Organic small-molecule luminescent materials have high fluorescence quantum efficiency, are easy to purify, and show advantages related to brightness. However, the low mobility of hole carriers hinders their practical applications. To obtain luminescent materials with high fluorescence quantum efficiency, we investigated organic small-molecule thiophene oligomers with electron-donating or electron-accepting substituents at the terminal groups using the density functional theory. Compared with the electron-donating groups (–NH2, –CH3, –C2H5, and –C3H7), the electron-withdrawing groups (–NO2 and –COOH) resulted in unusual electronic and photoluminescent properties. The ultraviolet spectra of the thiophene oligomer derivatives could be modulated in the range of 200–500 nm, making them suitable for application in organic light-emitting devices. In particular, the group with the strongest electron-withdrawing effect (–NO2) resulted in blue light emission in the wavelength range of 400–480 nm, suitable for application in blue chips. Finally, the calculation results show that the donor–acceptor-modified oligomers are worthy of synthesis due to their relatively high electron mobilities.
The vacuum arc ion source for indium and tin ions implantation into phase change memory thin films
Authors: Seleznev Dmitry , Kozlov Alexander , Kulevoy Timur , Sitnikov Alexey , Lazarenko Petr , Vorobyov Yuri , Smayev Mikhail , Yakubov Alexey , Sherchenkov Alexey , Kozyukhin Sergey
Published: December 2019

One of the most prospective electrical and optical nonvolatile memory types is the phase change memory based on chalcogenide materials, particularly Ge2Sb2Te5. Introduction of dopants is an effective method for the purposeful change of Ge2Sb2Te5 thin film properties. In this work, we used the ion implantation method for the introduction of In and Sn into Ge2Sb2Te5 thin films by a Multipurpose Test Bench (MTB) at the National Research Center “Kurchatov Institute”-Institute for Theoretical and Experimental Physics. For Sn and In ion implantation into Ge2Sb2Te5, the following MTB elements were used: a vacuum arc ion source, an electrostatic focusing system, and a system for current and beam profile measurements. The MTB parameters for Sn and In ion implantation and its effect on the material properties are presented. Implanted Ge2Sb2Te5 thin films were irradiated by femtosecond laser pulses. It was shown that the ion implantation resulted in a decrease in the threshold laser fluence necessary for crystallization compared to the undoped Ge2Sb2Te5.
In-situ stress modulated ferroelectric photovoltaic effect in cluster-assembled TbFe2/Bi5Ti3FeO15 heterostructural films
Authors: Bai Yulong , Yang Bo , Zhao Shifeng
Published: December 2019

TbFe2/Bi5Ti3FeO15 heterostructural films were prepared by inserting cluster-assembled TbFe2 microdiscs into a Bi5Ti3FeO15 matrix using low energy cluster beam deposition combined with sol-gel methods. The phase structure, ferroelectric properties, bandgap, photovoltaic spectral response, and performances of the ferroelectric photovoltaic effect were modulated by the in situ stress driven by magnetostriction of TbFe2 clusters under external magnetic fields. The short-circuit current, open-circuit voltage, and power conversation efficient increase with the in situ stress, reaching 0.026 mA/cm2, 9.5 V, and 5.88 × 10−2%, respectively, under a maximum in-stress of 0.075 GPa. So the high open-circuit voltage above bandgap is attributed to the distinct bandgap shifting and the effective separation of photogenerated electron-hole pairs derived from the in situ stress induced large built-in field. The in situ stress dominated symmetry breaking contributes to the improvement of the power conversation coefficient. The in situ dynamic internal stress provides a high efficient approach to modulate and improve ferroelectric photovoltaic effects.
Hydrogenation of small hydrocarbons on MgO supported Pd nanoparticles: The A-E-model expanded
Authors: Krause Maximilian , Rötzer Marian D. , Crampton Andrew S. , Huber Maximilian , Heiz Ueli
Published: December 2019

The hydrogenation of ethylene and acetylene was studied on a Pdn/MgO/Mo(100) model system containing palladium particles with a narrow size distribution around Pd26 (Pd20 to Pd35). Reactivity measurements were carried out in an ultrahigh vacuum chamber under isothermal conditions in the presence of deuterium. The catalyst system can readily hydrogenate both of these small molecules, and for acetylene, an alternative reaction network exists, in which it is trimerized to benzene. Distinct deactivation behavior was found for the two molecules and ascribed to different adsorption sites formed and influenced by the carbonaceous overlayer formed during the course of the reaction. These findings extend the A-E-model by Borodziński and Gołȩbiowski to extremely small particles and low partial pressures and show that it is possible to study realistic catalytic sites under highly defined conditions.
Magnetic properties and microstructures of high heat-resistance Sm-Co magnets with high Fe and low Zr content
Authors: Machida Hiroaki , Fujiwara Teruhiko , Fujimoto Chieko , Kanamori Yu , Sakakura Kenji , Takezawa Masaaki
Published: December 2019

The magnetic properties and microstructures of 2-17 type Sm-Co magnets with high Fe and low Zr content were investigated. The developed magnet achieved maximum energy product, [BH]m of 34.5 MGOe, intrinsic coercivity, Hcj of 21.3 kOe and squareness of 73.3% at 25 °C. Temperature coefficients of remanent magnetic flux density, Br and Hcj were 0.034%/K and 0.28%/K respectively, which values were almost as same as the conventional Sm-Co magnets. Moreover, the developed magnets had high magnetization orientation. For XRD, it was found that Zr was preferentially substituted by Co-Co pair, this made interaction between Co and Co stronger, so that heat resistance was maintained. Magnetic domain structures were observed with a Kerr effect microscope, and then it was observed that the developed magnet had strong pinning force. In the microstructures, the developed magnet had 200∼500 nm cell size with Fe and Cu separated clearly. This led to large gap of domain wall energy which produces strong pinning force. Because the developed magnet had high magnetization orientation and large gap of domain wall energy, we achieved high magnetic properties and high heat resistance on the developed magnet.
Microscopic theory of the influence of strong attractive forces on the activated dynamics of dense glass and gel forming fluids
Authors: Ghosh Ashesh , Schweizer Kenneth S.
Published: December 2019

We theoretically study the nonmonotonic (re-entrant) activated dynamics associated with a finite time scale kinetically defined repulsive glass to fluid to attractive glass transition in high volume fraction particle suspensions interacting via strong short range attractive forces. The classic theoretical “projection” approximation that replaces all microscopic forces by a single effective force determined solely by equilibrium pair correlations is revisited based on the “projectionless dynamic theory” (PDT). A hybrid-PDT approximation is formulated that explicitly quantifies how attractive forces induce dynamical constraints, while singular hard core interactions are treated based on the projection approach. Both the effects of interference between repulsive and attractive forces, and structural changes due to attraction-induced bond formation that competes with caging, are included. Combined with the microscopic Elastically Collective Nonlinear Langevin Equation (ECNLE) theory of activated relaxation, the resultant approach appears to properly capture both the re-entrant dynamic crossover behavior and the strong nonmonotonic variation of the activated structural relaxation time with attraction strength and range at very high volume fractions as observed experimentally and in simulations. Testable predictions are made. Major differences compared to both ideal mode coupling theory and ECNLE theory based on the full force projection approximation are identified. Calculations are also performed for smaller time and length scale intracage dynamics relevant to the non-Gaussian parameter based on analyzing the dynamic free energy that controls particle trajectories. Implications of the new theory for thermal glass forming liquids with relatively long range attractive forces are briefly analyzed.
Properties of self-mixing interference in terahertz distributed feedback quantum cascade lasers
Authors: Ge Lei , Yang Ning , Wang Jian , Li Yuanyuan , Chu Weidong , Duan Suqing , Xie Yan
Published: December 2019

The properties of self-mixing interference in terahertz distributed feedback quantum cascade lasers (THz DFB-QCLs) were studied by coupled wave theory and the multimode rate equation method. Under weak self-mixing optical feedback, the response behaviors of the DFB-QCLs are similar to those of Fabry–Pérot lasers and can be described by the Lang–Kobayashi equations with a modified feedback parameter. The amplitudes of the self-mixing power and frequency signals decrease with the increasing DFB coupling factor. Under strong feedback, new side modes arise, which broaden the laser linewidth. The number of side modes decreases with the increasing DFB coupling factor. The simulation also demonstrates that the maximum power mode of a THz DFB-QCL under strong self-mixing feedback is the minimum linewidth mode. These results support the development of self-mixing interferometers based on DFB-QCLs.
On collinear steady-state gravity waves with an infinite number of exact resonances
Authors: Yang Xiaoyan , Li Jiyang , Liao Shijun
Published: December 2019

In this paper, we investigate the nonlinear interaction of two primary progressive waves traveling in the same/opposite direction. Without loss of generality, two cases are considered: waves traveling in the same direction and waves traveling in the opposite direction. There exist an infinite number of resonant wave components in each case, corresponding to an infinite number of singularities in mathematical terms. Resonant wave systems with an infinite number of singularities are rather difficult to solve by means of traditional analytic approaches such as perturbation methods. However, this mathematical obstacle is easily cleared by means of the homotopy analysis method (HAM): the infinite number of singularities can be completely avoided by choosing an appropriate auxiliary linear operator in the frame of the HAM. In this way, we successfully gain steady-state systems with an infinite number of resonant components, consisting of the nonlinear interaction of the two primary waves traveling in the same/opposite direction. In physics, this indicates the general existence of so-called steady-state resonant waves, even in the case of an infinite number of resonant components. In mathematics, it illustrates the validity and potential of the HAM to be applied to rather complicated nonlinear problems that may have an infinite number of singularities.
Nonlinear optical effect of interlayer charge transfer in a van der Waals heterostructure
Authors: Yao Peng , He Dawei , Zereshki Peymon , Wang Yongsheng , Zhao Hui
Published: December 2019

The recently discovered two-dimensional materials can be used to fabricate multilayer heterostructures. Interlayer charge transfer is a key process in such heterostructures as it can enable emergent optoelectronic properties. Efficient interlayer charge transfer in van der Waals heterostructures has been observed by femtosecond transient absorption and steady-state optical spectroscopy measurements, based on measuring the interlayer carrier distribution. Here, we show that a second harmonic generation process allows direct probing of the electric field induced by the charge transfer. An ultrashort laser pulse was used to excite electrons and holes in a MoS2/WS2 heterostructure. The separation of the electrons and holes from the two monolayers generates an electric field, which enables the generation of the second harmonic of an incident fundamental pulse. We further studied the time evolution of this electric field by measuring the second harmonic signal as a function of the time delay between the pump and the fundamental pulses. The result agrees well with the dynamics revealed by a transient absorption measurement. These results provide direct evidence of interlayer charge transfer and demonstrate an all-optical method of studying charge transfer and induced electric fields in two-dimensional materials. Furthermore, this effect, if large enough, could be utilized in optical devices based on 2D heterostructures with nonlinear optical responses controllable by interlayer charge transfer.
Significant coercivity enhancement at low temperatures in magnetically oriented cobalt ferrite nanoparticles
Authors: Tancredi Pablo , Rivas-Rojas Patricia C. , Moscoso-Londoño Oscar , Muraca Diego , Knobel Marcelo , Socolovsky Leandro M.
Published: December 2019

The present work describes a synthesis and characterization strategy employed to study the magnetic anisotropic properties of a diluted nanoparticulate system. The system under analysis is composed of monodisperse and highly crystalline 16 nm Co0.5Fe2.5O4 nanoparticles (NPs), homogenously dispersed in 1-octadecene. Owing to the liquid nature of the matrix at room temperature, the relative orientation of the nanoparticle easy axis can be controlled by an external magnetic field, enabling us to measure how the magnetic properties are modified by the alignment of the particles within the sample. In turn, by employing this strategy, we have found a significant hardness and squareness enhancement of the hysteresis loop in the magnetically oriented system, with the coercive field reaching a value as high as 30.2 kOe at low temperatures. In addition, the magnetic behavior associated with the system under study was supported by additional magnetic measurements, which were ascribed to different events expected to take place throughout the sample characterization, such as the melting process of the 1-octadecene matrix or the NP relaxation under the Brownian mechanism at high temperatures.
Wavepacket golden rule treatment of interparticle Coulombic decay in paired quantum dots
Authors: Berg Matthias , Uranga-Piña Llinersy , Martínez-Mesa Aliezer , Bande Annika
Published: December 2019

The interparticle Coulombic decay process in paired quantum dots is studied by electron dynamics calculations. We consider a pair of Coulomb-coupled one-electron charged gallium arsenide quantum dots embedded in a nanowire. The two-electron decay process is approximately described by a single active electron model. Within this model, we employ the time-dependent wavepacket approach to the Fermi golden rule (introduced in the context of vibrational predissociation) to calculate autoionization rates, which are compared to exact rates obtained from fully correlated two-electron dynamics calculations. We found that the approximate decay rates agree well with the exact results in the limit of sufficiently separated quantum dots. Finally, we explore whether the short-range behavior of the new model can be further enhanced by the inclusion of local exchange effects by means of regularization of the Coulomb-potential based on a Jastrow-Slater wavefunction. The proposed method may open a route to study the interparticle Coulombic decay in more intricate systems, e.g., paired metal-nanoparticle—quantum dot systems.
Graphene-based thermal repeater
Authors: He Ming-Jian , Qi Hong , Ren Ya-Tao , Zhao Yi-Jun , Antezza Mauro
Published: December 2019

In this Letter, we have demonstrated the possibility to efficiently relay the radiative heat flux between two nanoparticles by opening a smooth channel for heat transfer. By coating the nanoparticles with a silica shell and modifying the substrate with multilayered graphene sheets, respectively, the localized phonon polaritons excited near the nanoparticles can couple with the multiple surface plasmon polaritons near the substrate to realize the heat relay at a long distance. The heat transfer can be enhanced by more than six orders of magnitude, and the relay distance can be as high as 35 times in the far-field regime. This work may provide a way to realize the energy modulation or thermal communications especially at long distances.
Using machine learning to assess short term causal dependence and infer network links
Authors: Banerjee Amitava , Pathak Jaideep , Roy Rajarshi , Restrepo Juan G. , Ott Edward
Published: December 2019

We introduce and test a general machine-learning-based technique for the inference of short term causal dependence between state variables of an unknown dynamical system from time-series measurements of its state variables. Our technique leverages the results of a machine learning process for short time prediction to achieve our goal. The basic idea is to use the machine learning to estimate the elements of the Jacobian matrix of the dynamical flow along an orbit. The type of machine learning that we employ is reservoir computing. We present numerical tests on link inference of a network of interacting dynamical nodes. It is seen that dynamical noise can greatly enhance the effectiveness of our technique, while observational noise degrades the effectiveness. We believe that the competition between these two opposing types of noise will be the key factor determining the success of causal inference in many of the most important application situations.
Fundamental limits to the transfer of energy harvested from ferroelectric materials under shock loading
Authors: Shkuratov Sergey I. , Baird Jason , Antipov Vladimir G. , Chase Jay B.
Published: December 2019

Ferroelectrics are capable of producing megawatt power levels under shock loading due to stress-induced phase transformations, resulting in depolarization of the ferroelectric materials. This power can be used for generation of high voltages, high currents, or ultrahigh-power electromagnetic radiation. The results are reported herein on an experimental study of limitations on energy harvested from shocked Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 and PbZr0.52Ti0.48O3 ferroelectrics and transferred to external electrical systems. The experimental results indicate that one of the limits to the energy transfer is electric breakdown that occurs within ferroelectric specimens during shock wave transit and depolarization, interrupting the energy transfer process and resulting in energy losses. It was revealed that the mechanism for breakdown in shocked ferroelectrics differs depending on the energy transfer time range, making a significant impact on the energy transfer process. High-speed photography and analysis of outputs for the two ferroelectrics indicate that for energy transfer times exceeding eight microseconds, the mechanical fragmentation of the ferroelectric material caused by the shock and resulting release waves following the shock wave front plays an important part in the breakdown process, while a thermal runaway dominates the breakdown at shorter energy transfer times. The heretofore disregarded mechanism of electric breakdown of the mechanically fragmented dielectric media is an unavoidable time-limiting factor for energy transfer from ferroelectrics under shock loading. The results obtained in this study are important for understanding the behavior of ferroelectrics during shock wave transit under high electric fields and for ultrahigh-power applications of ferroelectric materials.
Quantifying the flux as the driving force for nonequilibrium dynamics and thermodynamics in non-Michaelis–Menten enzyme kinetics
Authors: Liu Qiong , Wang Jin
Published: December 2019

Significance

The driving forces for a nonequilibrium dynamical system have been theoretically identified as the underlying landscape and the curl flux. However, the experimental quantification of curl flux remains challenging. We carried out a single-molecule enzymatic reaction dynamics study of horseradish peroxidase and found reaction rates showing significant deviations from the conventional Michaelis–Menten behavior. We quantified the nonequilibrium curl flux as the origin of such deviation. We also quantified the thermodynamic driving force through chemical potentials and dissipation cost with entropy production. We found flux, chemical potential, and entropy production all originated from the heat absorbed into the enzyme reaction system. This study provided a framework for quantifying the nonequilibrium driving forces both at the dynamic and the thermodynamic levels.
Kappa-on-Heavy (KoH) bodies are a distinct class of fully-human antibody-like therapeutic agents with antigen-binding properties
Authors: Macdonald Lynn E. , Meagher Karoline A. , Franklin Matthew C. , Levenkova Natasha , Hansen Johanna , Badithe Ashok T. , Zhong Maggie , Krueger Pamela , Rafique Ashique , Tu Naxin , Shevchuk James , Wadhwa Saurabh , Ehrlich George , Bautista Joannie , Grant Craig , Esau Lakeisha , Poueymirou William T. , Auerbach Wojtek , Morton Lori , Babb Robert , Chen Gang , Huang Tammy , MacDonald Douglas , Graham Kenneth , Gurer Cagan , Voronina Vera A. , McWhirter John R. , Guo Chunguang , Yancopoulos George D. , Murphy Andrew J.
Published: December 2019

We describe a Kappa-on-Heavy (KoH) mouse that produces a class of highly diverse, fully human, antibody-like agents. This mouse was made by replacing the germline variable sequences of both the Ig heavy-chain (IgH) and Ig kappa (IgK) loci with the human IgK germline variable sequences, producing antibody-like molecules with an antigen binding site made up of 2 kappa variable domains. These molecules, named KoH bodies, structurally mimic naturally existing Bence-Jones light-chain dimers in their variable domains and remain wild-type in their antibody constant domains. Unlike artificially diversified, nonimmunoglobulin alternative scaffolds (e.g., DARPins), KoH bodies consist of a configuration of normal Ig scaffolds that undergo natural diversification in B cells. Monoclonal KoH bodies have properties similar to those of conventional antibodies but exhibit an enhanced ability to bind small molecules such as the endogenous cardiotonic steroid marinobufagenin (MBG) and nicotine. A comparison of crystal structures of MBG bound to a KoH Fab versus a conventional Fab showed that the KoH body has a much deeper binding pocket, allowing MBG to be held 4 Å further down into the combining site between the 2 variable domains.
CCR2 inhibition reduces tumor myeloid cells and unmasks a checkpoint inhibitor effect to slow progression of resistant murine gliomas
Authors: Flores-Toro Joseph A. , Luo Defang , Gopinath Adithya , Sarkisian Matthew R. , Campbell James J. , Charo Israel F. , Singh Rajinder , Schall Thomas J. , Datta Meenal , Jain Rakesh K. , Mitchell Duane A. , Harrison Jeffrey K.
Published: December 2019

Significance

Standard of care for glioblastoma (GBM) results in median survival of <15 mo with 5-y survival <10%, highlighting the need for novel treatments. Immune checkpoint blockade has been successful in various cancer subtypes. However, success has not extended to GBM, largely due to the characteristically immune-suppressive glioma microenvironment. Here, we report targeting of myeloid derived suppressor cells (MDSCs), via inhibition of CCR2, unmasks efficacy of checkpoint blockade in GBM. Using checkpoint inhibitor-resistant murine glioma models, we show combination treatment reduces MDSCs and increases functional T cells within the tumors, and significantly extends overall survival. Our results support targeting of CCR2-expressing myeloid cells to enhance immunotherapies for GBM, and warrant translation of this approach to early human clinical trials.
The circadian clock protein REVERBα inhibits pulmonary fibrosis development
Authors: Cunningham Peter S. , Meijer Peter , Nazgiewicz Alicja , Anderson Simon G. , Borthwick Lee A. , Bagnall James , Kitchen Gareth B. , Lodyga Monika , Begley Nicola , Venkateswaran Rajamiyer V. , Shah Rajesh , Mercer Paul F. , Durrington Hannah J. , Henderson Neil C. , Piper-Hanley Karen , Fisher Andrew J. , Chambers Rachel C. , Bechtold David A. , Gibbs Julie E. , Loudon Andrew S. , Rutter Martin K. , Hinz Boris , Ray David W. , Blaikley John F.
Published: December 2019

Pulmonary inflammatory responses lie under circadian control; however, the importance of circadian mechanisms in the underlying fibrotic phenotype is not understood. Here, we identify a striking change to these mechanisms resulting in a gain of amplitude and lack of synchrony within pulmonary fibrotic tissue. These changes result from an infiltration of mesenchymal cells, an important cell type in the pathogenesis of pulmonary fibrosis. Mutation of the core clock protein REVERBα in these cells exacerbated the development of bleomycin-induced fibrosis, whereas mutation of REVERBα in club or myeloid cells had no effect on the bleomycin phenotype. Knockdown of REVERBα revealed regulation of the little-understood transcription factor TBPL1. Both REVERBα and TBPL1 altered integrinβ1 focal-adhesion formation, resulting in increased myofibroblast activation. The translational importance of our findings was established through analysis of 2 human cohorts. In the UK Biobank, circadian strain markers (sleep length, chronotype, and shift work) are associated with pulmonary fibrosis, making them risk factors. In a separate cohort, REVERBα expression was increased in human idiopathic pulmonary fibrosis (IPF) lung tissue. Pharmacological targeting of REVERBα inhibited myofibroblast activation in IPF fibroblasts and collagen secretion in organotypic cultures from IPF patients, thus suggesting that targeting of REVERBα could be a viable therapeutic approach.
Mouse genetics reveals Barttin as a genetic modifier of Joubert syndrome
Authors: Ramsbottom Simon A. , Thelwall Peter E. , Wood Katrina M. , Clowry Gavin J. , Devlin Laura A. , Silbermann Flora , Spiewak Helena L. , Shril Shirlee , Molinari Elisa , Hildebrandt Friedhelm , Gunay-Aygun Meral , Saunier Sophie , Cordell Heather J. , Sayer John A. , Miles Colin G.
Published: December 2019

Significance

Our current understanding of genetic disease is often inadequate, largely due to genetic background effects that modify disease presentation. This is particularly challenging for rare diseases that lack sufficient numbers of patients for genome-wide association studies. We show in a series of experiments using a murine model of Joubert syndrome, a multisystem ciliopathy, that a single locus is a modifier of cystic kidney disease. We go on to show that the human homolog plays a similar role in disease using a cohort of patients. These findings make a significant contribution to the underplayed (and often ignored) role of genetic background in murine models and how this can be exploited to understand further rare inherited disease.
Energy conservation involving 2 respiratory circuits
Authors: Schoelmerich Marie Charlotte , Katsyv Alexander , Dönig Judith , Hackmann Timothy J. , Müller Volker
Published: December 2019

Significance

The chemiosmotic mechanism is a central mode of energy conservation for microorganisms. It relies on a respiratory chain that couples electron flow at the membrane to the transport of ions across the cytoplasmic membrane. This electrochemical potential fuels a rotary machine, the ATP synthase, to make intracellular ATP. Here, we show that a strictly anaerobic rumen bacterium uses 2 different ion circuits for energy conservation. This is achieved by employing 2 ATP synthases that are driven by a

H

+

or Na
+
gradient. The mixed gradient is established by 2 distinct ion pumps. The

H

+

gradient is formed by the Ech complex, and the Na
+
gradient is formed by the Rnf complex.
Determinants governing T cell receptor α/β-chain pairing in repertoire formation of identical twins
Authors: Tanno Hidetaka , Gould Timothy M. , McDaniel Jonathan R. , Cao Wenqiang , Tanno Yuri , Durrett Russell E. , Park Daechan , Cate Steven J. , Hildebrand William H. , Dekker Cornelia L. , Tian Lu , Weyand Cornelia M. , Georgiou George , Goronzy Jörg J.
Published: December 2019

The T cell repertoire in each individual includes T cell receptors (TCRs) of enormous sequence diversity through the pairing of diverse TCR α- and β-chains, each generated by somatic recombination of paralogous gene segments. Whether the TCR repertoire contributes to susceptibility to infectious or autoimmune diseases in concert with disease-associated major histocompatibility complex (MHC) polymorphisms is unknown. Due to a lack in high-throughput technologies to sequence TCR α–β pairs, current studies on whether the TCR repertoire is shaped by host genetics have so far relied only on single-chain analysis. Using a high-throughput single T cell sequencing technology, we obtained the largest paired TCRαβ dataset so far, comprising 965,523 clonotypes from 15 healthy individuals including 6 monozygotic twin pairs. Public TCR α- and, to a lesser extent, TCR β-chain sequences were common in all individuals. In contrast, sharing of entirely identical TCRαβ amino acid sequences was very infrequent in unrelated individuals, but highly increased in twins, in particular in CD4 memory T cells. Based on nucleotide sequence identity, a subset of these shared clonotypes appeared to be the progeny of T cells that had been generated during fetal development and had persisted for more than 50 y. Additional shared TCRαβ in twins were encoded by different nucleotide sequences, implying that genetic determinants impose structural constraints on thymic selection that favor the selection of TCR α–β pairs with entire sequence identities.
Uncovering the functional residues of
Arabidopsis
isoprenoid biosynthesis enzyme HDS
Authors: Wang Jin-Zheng , Lei Yongxing , Xiao Yanmei , He Xiang , Liang Jiubo , Jiang Jishan , Dong Shangzhi , Ke Haiyan , Leon Patricia , Zerbe Philipp , Xiao Youli , Dehesh Katayoon
Published: December 2019

Significance

The MEP pathway is an essential and evolutionarily conserved metabolic route present in most pathogenic bacteria, plants, and malaria; and hence a target for discovery of agricultural and medical applications, and an engineering template for production of isoprenoids. The essential nature of this pathway and inherent intricacies associated with enzyme activity assays have hampered in vivo structure and functional analyses. Here, we report the suppressor screen leading to identification of 3 functionally conserved amino-acid residues positioned at the active site cavity and cofactor binding domain of the key MEP-pathway enzyme, HDS. The proposed roles of these residues in determining HDS enzyme activity and the MEP-pathway flux offer a platform for rational design of antiinfective drugs and synthetic engineering of isoprenoids.
High-yield monolayer graphene grids for near-atomic resolution cryoelectron microscopy
Authors: Han Yimo , Fan Xiao , Wang Haozhe , Zhao Fang , Tully Christopher G. , Kong Jing , Yao Nan , Yan Nieng
Published: December 2019

Cryogenic electron microscopy (cryo-EM) has become one of the most powerful techniques to reveal the atomic structures and working mechanisms of biological macromolecules. New designs of the cryo-EM grids—aimed at preserving thin, uniform vitrified ice and improving protein adsorption—have been considered a promising approach to achieving higher resolution with the minimal amount of materials and data. Here, we describe a method for preparing graphene cryo-EM grids with up to 99% monolayer graphene coverage that allows for more than 70% grid squares for effective data acquisition with improved image quality and protein density. Using our graphene grids, we have achieved 2.6-Å resolution for streptavidin, with a molecular weight of 52 kDa, from 11,000 particles. Our graphene grids increase the density of examined soluble, membrane, and lipoproteins by at least 5-fold, affording the opportunity for structural investigation of challenging proteins which cannot be produced in large quantity. In addition, our method employs only simple tools that most structural biology laboratories can access. Moreover, this approach supports customized grid designs targeting specific proteins, owing to its broad compatibility with a variety of nanomaterials.
Effect of process parameters on residual stress in selective laser melting of AlSi10Mg
Authors: Jiang Xiaohui , Ye Tong , Zhu Yihong
Published: December 2019

Residual stress is a key indicator for measuring complex additive components, and its control method has received extensive attention. In this study, the finite element simulation of selective laser melting of AlSi10Mg was performed. It is found that the opposite laser scanning strategy can reduce the final residual stress of the sample. The effect of preheating the substrate to control the residual stress within a certain temperature range is obvious, and the laser scanning speed has the greatest influence on the Z-direction residual stress of the sample. The results show that the sag phenomenon is easy to occur at the laser scanning starting position, and the formed layer is the maximum residual stress region at the junction with the substrate.
Synergistic factors control kinase–phosphatase organization in B-cells engaged with supported bilayers
Authors: Núñez Marcos Francisco , Wisser Kathleen , Veatch Sarah L.
Published: December 2019

Cell membranes can influence local concentrations of signaling regulators around receptors via multiple physical mechanisms. It is shown that ordered, phase-like membrane domains can synergize with other mechanisms to enhance B-cell receptor signaling.
Spire stimulates nucleation by Cappuccino and binds both ends of actin filaments
Authors: Bradley Alexander O. , Vizcarra Christina L. , Bailey Hannah M. , Quinlan Margot E.
Published: December 2019

The actin nucleators Cappuccino and Spire collaborate to build an actin mesh in oocytes. We resolve two questions regarding their mechanism of action: Spire binds both barbed and pointed ends of actin filaments; however, barbed-end binding is not necessary for oogenesis or synergistic actin assembly.
Arbitration and tax treaty disputes
Authors: Markham Michelle Andrea
Published: December 2019

The Organisation for Economic Cooperation and Development’s Base Erosion and Profit Shifting Action Plan and its implementation around the world over the last few years has brought about widespread and fundamental changes to the international tax framework. A corollary of these changes has been an increase in international tax treaty disputes, as newly-designed rules are challenged by both taxpayers and tax administrations. This article seeks to examine how such controversies have been addressed in the past, and to evaluate whether in this new environment arbitration may provide the key to successful tax treaty dispute resolution, despite concerns regarding national sovereignty. It considers the changes effected to the traditional tax treaty dispute resolution mechanism under the Mutual Agreement Procedure by the Action 14 Final Report on Making Dispute Resolution Mechanisms More Effective. Furthermore, it evaluates the use of arbitration under the Multilateral Instrument, as well as the application of certain reservations and options available in this regard. It explores some of the benefits of instituting an arbitration procedure that will ensure resolution for all international stakeholders. Finally, it considers the potential for Advance Pricing Agreements to proactively resolve tax treaty disputes, and the need for taxpayers to take a strategic and informed view of controversy management in the international tax sphere.
Mild Stage 1 post-operative acute kidney injury: association with chronic kidney disease and long-term survival
Authors: Long Thorir Einarsson , Helgason Dadi , Helgadottir Solveig , Sigurdsson Gisli Heimir , Palsson Runolfur , Sigurdsson Martin Ingi , Indridason Olafur Skuli
Published: December 2019

Background

Mild cases of acute kidney injury (AKI) are identified by a small rise in serum creatinine (SCr) according to the KDIGO AKI definition. The aim of this study was to examine the long-term outcomes of individuals with mild AKI.

Methods. This was a retrospective cohort study of all adult patients who underwent abdominal, cardiothoracic, vascular or orthopaedic surgery at Landspitali–The National University Hospital of Iceland in 1998–2015. Incident chronic kidney disease (CKD), progression of pre-existing CKD and long-term survival were compared between patients with mild Stage 1 AKI (defined as a rise in SCr of ≥26.5 μmol/L within 48 h post-operatively without reaching 1.5× baseline SCr within 7 days), and a propensity score-matched control group without AKI stratified by the presence of CKD.

Results

Pre- and post-operative SCr values were available for 47 333 (42%) surgeries. Of those, 1161 (2.4%) had mild Stage 1 AKI and 2355 (5%) more severe forms of AKI. Mild Stage 1 AKI was associated with both incident CKD and progression of pre-existing CKD (P < 0.001). After exclusion of post-operative deaths within 30 days, mild Stage 1 AKI was not associated with worse 1-year survival in patients with preserved kidney function (94% versus 94%, P = 0.660), and same was true for patients with pre-operative CKD (83% versus 82%, P = 0.870) compared with their matched individuals.

Conclusions. Mild Stage 1 AKI is associated with development and progression of CKD, but not with inferior 1-year survival. These findings support the inclusion of a small absolute increase in SCr in the definition of AKI.
Stable isotopes suggest the location of marine feeding grounds of South European Atlantic salmon in Greenland
Authors: Almodóvar Ana , Nicola Graciela G , Ayllón Daniel , Trueman Clive N , Davidson Ian , Kennedy Richard , Elvira Benigno
Published: December 2019

Historical data on the oceanic distribution and migration routes of southernmost Atlantic salmon Salmo salar populations from Europe are almost non-existent, as no rigorous tagging initiatives have been conducted. Here, we used stable isotope data (δ13C and δ15N) of historic scale collections to identify the potential marine feeding areas of the largest salmon population in the Iberian Peninsula. Data were compared with published datasets from Northern Ireland, Wales, south England, and northeast UK coast, which correspond to series between 15- and 33-year long within the time period from 1958 to 2009. Temporal covariation in sea surface temperature, primary productivity, and δ13C values suggests that feeding areas of Iberian salmon are located around Greenland, both in the Labrador and the Irminger seas. Furthermore, δ13C values of Atlantic salmon from Canadian rivers reported in the literature are similar to those found in individuals from Spanish rivers. Our results suggest that Iberian salmon follow a westerly migration route towards Greenland instead of following the easterly branch of the North Atlantic current into the Norwegian Sea. Characterization of feeding patterns and migration routes might help to understand the causes of ongoing population decline and establish targeted conservation programmes for threatened Iberian salmon.
A narrative review of the impact of the transition to ICD-10 and ICD-10-CM/PCS
Authors: Kusnoor Sheila V , Blasingame Mallory N , Williams Annette M , DesAutels Spencer J , Su Jing , Giuse Nunzia Bettinsoli
Published: December 2019

Objectives

The United States transitioned to the tenth version of the International Classification of Diseases (ICD) system (ICD-10) for mortality coding in 1999 and to the International Classification of Diseases, Clinical Modification and Procedure Coding System (ICD-10-CM/PCS) on October 1, 2015. The purpose of this study was to conduct a narrative literature review to better understand the impact of the implementation of ICD-10/ICD-10-CM/PCS.

Materials and Methods

We searched English-language articles in PubMed, Web of Science, and Business Source Complete and reviewed websites of relevant professional associations, government agencies, research groups, and ICD-10 news aggregators to identify literature on the impact of the ICD-10/ICD-10-CM/PCS transition. We used Google to search for additional gray literature and used handsearching of the references of the most on-target articles to help ensure comprehensiveness.

Results

Impact areas reported in the literature include: productivity and staffing, costs, reimbursement, coding accuracy, mapping between ICD versions, morbidity and mortality surveillance, and patient care. With the exception of morbidity and mortality surveillance, quantitative studies describing the actual impact of the ICD-10/ICD-10-CM/PCS implementation were limited and much of the literature was based on the ICD-10-CM/PCS transition rather than the earlier conversion to ICD-10 for mortality coding.

Discussion

This study revealed several gaps in the literature that limit the ability to draw reliable conclusions about the overall impact, positive or negative, of moving to ICD-10/ICD-10-CM/PCS in the United States.

Conclusion

These knowledge gaps present an opportunity for future research and knowledge sharing and will be important to consider when planning for ICD-11.
Placement of Guide-Wireless Sharp Percutaneous Pedicle Screws Utilizing Computed Tomography-Navigation and Sentinel Fluoroscopy: 2-Dimensional Operative Video
Authors: Martirosyan Nikolay L , Wewel Joshua T , Uribe Juan S
Published: December 2019

Many established techniques exist for minimally invasive pedicle screw placement. Nearly all techniques incorporate the use of a Kershner wire (K-wire) at various points in the work-flow. The use of a K-wire adds an additional step. If its position is lost, it requires repeating all previous steps, and placement is not without complication. The use of a guide-wireless sharp screws allows the surgeon to place a pedicle screw in 1 step with several fluid maneuvers.
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The patient underwent Institutional Review Board-approved consent for this study. Following traditional computed tomography-based navigation, a stab incision is made, followed by fascial dissection with monopolar cautery. The sharp screw is placed percutaneously at the facet-transverse process junction. The precise entry point is confirmed with navigation, followed by a sentinel anterior-posterior fluoroscopic image, verifying the accuracy of the navigation. The cortical bone is traversed by malleting the sharp tip through the cortex. When the cancellous bone is engaged, the screw is then advanced through the pedicle. This set of steps allows for safe, efficient placement of percutaneous pedicle screws without the need for a guidewire. Mal-placement regarding sharp pedicle screw insertion is similar to K-wire-dependent screw placement. Surgeons must be cognoscente of exceptionally sclerotic bone, which can prove difficult to cannulate. Conversely, osteoporotic bone that is liable to a cortical pedicle breach, transverse process fracture, and/or maltrajectory are all considerations when placing a K-wireless, sharp pedicle screw. Anterior-posterior fluoroscopy is utilized to confirm accuracy of image-guided navigation and mitigate malplacement of pedicle screws.
Evaluating the Role of Self-Esteem on Differential Career Outcomes by Gender in Academic Medicine
Authors: Manne-Goehler Jennifer , Freund Karen M. , Raj Anita , Kaplan Samantha E. , Terrin Norma , Breeze Janis L. , Carr Phyllis L.
Published: December 2019

Purpose

Gender differences in faculty advancement persist in academic medicine. Understanding of what drives these differences remains limited. The relationship among self-esteem, gender, and career outcomes has not previously been explored.

Method

The authors evaluated the association between gender and 2012–2013 career outcomes, specifically, the number of publications, academic rank, leadership positions, and retention, and whether self-esteem as measured in the 1995 National Faculty Survey mediates this relationship. They measured self-esteem using the modified Rosenberg Self-Esteem Scale. The authors used multivariable logistic regression analysis to understand the association among gender, self-esteem, and the outcomes of rank, leadership, and retention, and negative binomial models for number of publications. Models were adjusted for race, specialty, effort distribution, and years since first faculty appointment. The authors performed a mediation analysis to understand whether self-esteem mediates the relationship between gender and these career outcomes.

Results

Overall, self-esteem scores were high. Women had lower self-esteem in 1995 than their male colleagues. In adjusted models, female gender was associated with lower performance on all 4 career outcome metrics. While self-esteem scores were positively associated with all 4 outcomes, the authors’ mediation analysis suggested that self-esteem did not mediate the relationship between gender and these 4 career metrics.

Conclusions

Female medical faculty members lag behind men on traditional metrics of faculty achievement. While higher self-esteem is positively associated with faculty achievement, it did not mediate the relationship between gender and career advancement over the 17 years of follow-up and, thus, may not be an ideal target for programs and policies to increase gender parity in academic medicine.
Philosophy of Science Series: Harnessing the Multidisciplinary Edge Effect by Exploring Paradigms, Ontologies, Epistemologies, Axiologies, and Methodologies
Authors: Varpio Lara , MacLeod Anna
Published: December 2019

Health professions education (HPE) researchers come from many different academic traditions, from psychology to engineering to rhetoric. Trained in these traditions, HPE researchers engage in science and the building of new knowledge from different paradigmatic orientations. Collaborating across these traditions is particularly generative, a phenomenon the authors call the multidisciplinary edge effect. However, to harness this productivity, scholars need to understand their own paradigms and those of others so that collaboration can flourish. This Invited Commentary introduces the Philosophy of Science series—a collection of articles that introduce readers to 7 different paradigms that are frequently used in HPE research or that the authors suggest will be increasingly common in future studies. Each article in the collection presents a concise and accessible description of the main principles of a paradigm so that researchers can quickly grasp how these traditions differ from each other. In this introductory article, the authors define and illustrate key terms that are essential to understanding these traditions (i.e., paradigm, ontology, epistemology, methodology, and axiology) and explain the structure that each article in this series follows.
Thinking Sociomaterially: Why Matter Matters in Medical Education
Authors: MacLeod Anna , Ajjawi Rola
Published: December 2019

Sociomaterial perspectives in research are those that encourage researchers to focus their inquiry on the relationships between people (social) and things (material), rather than focusing solely on people. The unique possibility of sociomaterial perspectives is increasingly recognized in health professions education scholarship. In an effort to support those who may be interested in engaging with the principles of sociomaterialism in their own work, the authors have developed a primer on this paradigm of research. This Invited Commentary—one of several exploring different philosophies of science—offers an overview of the ontological, epistemological, axiological, and methodological foundations of sociomateriality. The authors then put these ideas into action, highlighting the philosophical foundations of sociomaterial perspectives in a sample case study that tells the story of Lee, a resident involved in a medical error.