bluuebunny/crossref_metadata_2025_split huggingface dataset:
Concerted variation of the 3′ regulatory region of Ig heavy chain and Gm haplotypes across human continental populations
Authors: Frezza Domenico , Martinez‐Labarga Cristina , Giambra Vincenzo , Serone Eliseo , Scano Giuseppina , Rickards Olga , D'Addabbo Pietro , Novelletto Andrea 
Published: January 2020

AbstractObjectivesThe 3′ regulatory region of the immunoglobulin heavy chain gene (IGH) includes the HS1.2 enhancer displaying length polymorphism with four known variants. The goal of the research was to provide an overview of this variability and of its evolutionary significance across human populations.Materials and MethodsWe compiled published and original data on HS1.2 polymorphism in 3,100 subjects from 26 human populations. Moreover, we imputed the haplotypic arrangement of the HS1.2 region in the 1000 Genomes Project (1KGP). In this dataset, imputation could also be obtained for the G1m‐G3m allotype by virtue of the precise correspondence between serological types and amino acid (and DNA) substitutions in IGHG1 and IGHG3.ResultsHS1.2 variant frequencies displayed similar patterns of continental partitioning as those reported in the literature for the physically neighboring IGHG1‐IGHG3 system. The 1KGP data revealed that linkage disequilibrium (LD) can explain the spread of joint HS1.2‐IGHG1‐IGHG3 associations across continents and within continental populations, with stronger LD out of Africa and the features of an evolutionarily stable genomic block with differential expression in lymphoblastoid cell lines.DiscussionStrong population structuring involves at least the entire 70 kb genomic region here considered, due to the tight LD which maintained HS1.2, IGHG1, and IGHG3 in nonrandom arrangements. This might be key to better understand the evolutionary path of the entire genomic region driven by immune response capabilities, during the formation of continental gene pools.
Collective Tunnelling of Strongly Interacting Cold Atoms in a Double‐Well Potential
Authors: Sokolovski Dmitri , Gutiérrez de la Cal Xavier , Pons Marisa 
Published: January 2020

AbstractIt is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double‐well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one‐atom‐at‐a‐time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually.
The Gravitational Energy–Momentum Density of Radially Accelerated Observers in Schwarzschild Spacetime
Authors: Formiga J. B. 
Published: January 2020

AbstractA hybrid machinery that is useful for calculations in teleparallel theories when the spacetime is spherically symmetric is developed. Using this machinery, the gravitational energy–momentum tensor density of the Schwarzschild spacetime is evaluated in a frame adapted to observers that accelerate in the radial direction. The energy density, the total energy, and the gravitational energy‐momentum flux are obtained. The regularization procedure and the limit where gravity is absent is discussed. It turns out that the regularized energy and energy–momentum flux are consistent in the whole spacetime. The continuity equation for the gravitational energy–momentum also holds for any point outside the black hole. Finally, the static and freely falling cases are discussed. It is found that a static observer measures a negative gravitational energy density, while a freely falling one measures a vanishing density.
Soft Lattice and Defect Covalency Rationalize Tolerance of β‐CsPbI3 Perovskite Solar Cells to Native Defects
Authors: Chu Weibin , Saidi Wissam A. , Zhao Jin , Prezhdo Oleg V. 
Published: January 2020

AbstractAlthough all‐inorganic metal halide perovskites (MHPs) have shown tremendous improvement, they are still inferior to the hybrid organic–inorganic MHPs in efficiency. Recently, a conceptually new β‐CsPbI3 perovskite reached 18.4 % efficiency combined with good thermodynamic stability at ambient conditions. We use ab initio non‐adiabatic molecular dynamics to show that native point defects in β‐CsPbI3 are generally benign for nonradiative charge recombination, regardless of whether they introduce shallow or deep trap states. These results indicate that MHPs do not follow the simple models used to explain defect‐mediated charge recombination in the conventional semiconductors. The strong tolerance is due to the softness of the perovskite lattice, which permits separation of electrons and holes upon defect formation, and only allows carriers to couple to the low‐frequency vibrations. Both factors decrease notably the non‐adiabatic coupling and slow down the dissipation of energy to heat.
Photodriven Active Ion Transport Through a Janus Microporous Membrane
Authors: Yang Jinlei , Liu Pengchao , He Xiao , Hou Junjun , Feng Yaping , Huang Zhiwei , Yu Lian , Li Lianshan , Tang Zhiyong 
Published: January 2020

AbstractPrecise control of ion transport is a fundamental characteristic for the sustainability of life. It remains a great challenge to develop practical and high‐performance artificial ion‐transport system that can allow active transport of ions (protons) in an all solid‐state nanoporous material. Herein, we develop a Janus microporous membrane by combining reduced graphene oxide (rGO) and conjugated microporous polymer (CMP) for controllable photodriven ion transport. Upon light illumination, a net ionic current is generated from the CMP to the rGO side of the membrane, indicating that the rGO/CMP Janus membrane can realize photodriven directional and anti‐gradient ion transport. Analogously to the p‐n junction in photovoltaic devices, light is firstly converted into separated charges to trigger a transmembrane potential, which subsequently drives directional ion movement. For the first time, this method enables integration of a photovoltaic effect with an ionic field to drive active ion transport. With the advantages of scaled up production and easy fabrication, the concept of photovoltaic ion transport based on Janus microporous membrane may find wide application in energy storage and conversion, photodriven ion‐sieving, and water treatment.
Solidification of sulfur and arsenic in gold concentrate and leaching of the gold by thiosulfate
Authors: He Yi , Hu Xianzhi , Zi Futing , Yang Baomin , Cheng Huiling 
Published: January 2020

AbstractThe processing of refractory minerals rich in arsenic and sulfur often causes give off arsenic and sulfur contamination during roasting and oxidation pretreatments. In this paper, the solidification of elemental arsenic and sulfur by adding calcium‐containing compounds (calcium oxide, calcium carbonate, and calcium hydroxide) during roasting and oxidation was investigated with the aim of reducing environmental pollution. At the same time, the gold leaching from residues produced by solidification roasting and oxidation using nontoxic and environmentally friendly green copper‐ammonia‐thiosulfate method was also studied. The results indicated that a relatively better solidification effect of SO2 and As2O3 was achieved by adding Ca (OH)2, with a solidification efficiency for sulfur and arsenic as 84.67% and 50%, respectively. When copper‐ammonia‐thiosulfate leaching was carried out on the residues after solidification roasting, it was found that a 90% gold leaching percentage was obtained. Via characterization using Brunauer–Emmett–Teller surface area, scanning electron microscope, X‐ray diffraction, and X‐ray photoelectron spectroscopy, it was also found that the arsenic and sulfur in arsenopyrite were oxidized into stable and safe sulfates and arsenates after solidification. The results show that solidification roasting oxidation is an efficient and environmentally friendly pretreatment method, and the gold in the calcine can be effectively leached out via the green copper‐ammonia‐thiosulfate system.
Processing–structure–property relationship in direct laser writing carbonization of polyimide
Authors: Wang Rui , Duan Xiaoshuang , Yao Jingwen , Ruan Xiaojun , Yao Yanbo , Liu Tao 
Published: January 2020

AbstractDirect laser writing carbonization (DLWc) of polyimide has recently emerged as a versatile method for facile fabrication of a variety of functional devices. Up‐to‐date, there is still a lack of comprehensive and in‐depth experimental studies to understand the processing‐structure–property relationship involved in this promising technique. With assistance of methylene blue adsorption as an in situ porous structure characterization method along with scanning electron microscopy, Raman scattering spectroscopy, X‐ray photoelectron spectroscopy, and electrical property measurements, we systematically investigate the multiscale structure evolution and the electrical sheet resistance of the carbon lines fabricated by DLWc at varied laser processing conditions. The key processing parameters being investigated included: laser power (P), laser beam scanning speed (S), distance of laser beam waist to the surface of polyimide film (D), and their combined effect—the averaged areal laser energy density—(E). Quantitative relationships are established between these processing parameters and the specific surface area, the porosity, the degree of perfection of the layered carbon or graphitic basic structure units, as well as the electrical sheet resistance of the carbon lines created by DLWc. The comprehensive and quantitative processing‐multiscale structure–electrical property relationships for DLWc established in this study expect to be useful for better understanding the complicated photo‐thermally induced polyimide pyrolysis/carbonization process.
A highly flexible, electrically conductive, and mechanically robust graphene/epoxy composite film for its self‐damage detection
Authors: Meng Qingshi , Kenelak Vincent , Chand Aron , Kang Hailan , Han Sensen , Liu Tianqing 
Published: January 2020

AbstractAdvanced functional composites have attracted a great attention for fabricating flexible devices. In this article, the GnP/epoxy composite film was prepared by mixing graphene platelets (GnPs) with epoxy through sonication process. The morphology, mechanical properties, and electrical conductivity of the prepared composites were investigated. As the GnP contents increased from 2.5 to 7.5 vol%, the composites showed an increase in strain sensitivity with the rapid decrease in the strain gauge to 4.4. Additionally, when dynamic movement of the flexible film was performed, at bending and twist angle of 135° and 180°, respectively, steady increase in both resistance changes were detected and compared. The electrical resistance of the flexible was measured over a temperature range of 20–95°C, an increase in temperature lead to a linearly equivalent increase in resistance. The composites can also detect slight pressure changes at 2 kPa compression force with rapid decrease of resistance. Additionally, fatigue test was performed with stable, sensitive, and no distinguishable reading under 2,000 stretching cycles. The composite film exhibits an excellent self‐sensing responds when fracture occurred. Thus, the obtained highly flexible, conductive, and mechanical robust composite sensor can be applied as advanced composites sensors for health monitoring.
Reversibly highly stretchable and self‐healable zwitterion‐containing polyelectrolyte hydrogel with high ionic conductivity for high‐performance flexible and cold‐resistant supercapacitor
Authors: Diao Wenjing , Wu Linlin , Ma Xiaofeng , Wang Lei , Bu Ximan , Ni Wei , Yang Xinfeng , Fang Ying 
Published: January 2020

AbstractIt remains challenging to develop stretchable and self‐healable polymer electrolytes with improved ion‐conductive nature for high‐performance multifunctional flexible supercapacitors. Herein, a P(AM‐SBMA‐AMPS)‐SiO2 zwitterion‐containing polyelectrolyte hydrogel is fabricated via copolymerization of acrylamide (AM), sulfobetaine methacrylate (SBMA) zwitterionic monomer, and 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) anionic monomer grafted from the surface of vinyl silica nanoparticles (VSNPs). The hydrogen bonding among polymer chains and the high‐density dynamic ionic interactions between SBMA and AMPS work as reversible “sacrificial bonds” to toughen hydrogel, while the VSNPs function as multifunctional crosslinkers and stress transfer centers, which makes these hydrogels tough (fracture energy 2.7 MJ m−3), stretchable (fracture strain 4,016%), and self‐healable (fracture strain of healable sample 775%). More importantly, this zwitterion‐containing polyelectrolyte hydrogel exhibits high ionic conductivities (3.4 S m−1) owing to the highly hydration capacity of the zwitterionic polyelectrolyte copolymer which produced efficient ion migration channels for ion transport. Accordingly, a flexible supercapacitor based on this multifunctional hydrogel as electrolyte demonstrates a high electric double‐layer capacitive capacitance of 60.6 F g−1 at 0.5 A g−1 and excellent capacitance retention of ~98% over 1,000 cycles as well as encouraging electrochemical properties at subzero temperature. This work provides new insights into the synthesis of highly conductive and multifunctional polyelectrolyte hydrogels for high‐performance flexible supercapacitors. © 2020 Wiley Periodicals, Inc.
Cryptic Chemical Communication: Secondary Metabolic Responses Revealed by Microbial Co‐culture
Authors: Liu Chao , Kakeya Hideaki 
Published: January 2020

AbstractMicrobial secondary metabolites (SMs) have long been viewed as a significant source of novel pharmaceutical and agrochemical molecules. With the increasing availability of genomic data, numerous biosynthetic gene clusters (BGCs) have been discovered. Despite the presence of tens of thousands of BGCs that can theoretically produce extremely diverse SMs, many gene clusters remain in a silent state under axenic culture conditions. Co‐culture is a promising research approach as it stimulates the expression of cryptic BGCs to produce novel metabolites and also mimics natural interspecies interactions in a laboratory environment. In recent years, the roles of SMs in microbial communication have caught the attention of researchers and our understanding of microbes and their production of remarkable SMs has improved. SMs may be extensively involved in a variety of communication events among microorganisms. We herein summarize certain representative findings in the field of chemical communication involving SMs in co‐culture systems.
Bottom‐Up Fabrication of a Sandwich‐Like Carbon/Graphene Heterostructure with Built‐In FeNC Dopants as Non‐Noble Electrocatalyst for Oxygen Reduction Reaction
Authors: Lv Xiaoxia , Xue Xue , Gan Xingyu , Lv Chenhao , Sun Xiaochen , Wang Yun , Li Liangjun , Wang Hua 
Published: January 2020

AbstractHigh‐performance non‐noble electrocatalysts for oxygen reduction reaction (ORR) are the prerequisite for large‐scale utilization of fuel cells. Herein, a type of sandwiched‐like non‐noble electrocatalyst with highly dispersed FeNx active sites embedded in a hierarchically porous carbon/graphene heterostructure was fabricated using a bottom‐up strategy. The in situ ion substitution of Fe3+ in a nitrogen‐containing MOF (ZIF‐8) allows the Fe‐heteroatoms to be uniformly distributed in the MOF precursor, and the assembly of Fe‐doped ZIF‐8 nano‐crystals with graphene‐oxide and in situ reduction of graphene‐oxide afford a sandwiched‐like Fe‐doped ZIF‐8/graphene heterostructure. This type of heterostructure enables simultaneous optimization of FeNx active sites, architecture and interface properties for obtaining an electron‐catalyst after a one‐step carbonization. The synergistic effect of these factors render the resulting catalysts with excellent ORR activities. The half‐wave potential of 0.88 V vs. RHE outperforms most of the none‐noble metal catalyst and is comparable with the commercial Pt/C (20 wt %) catalyst. Apart from the high activity, this catalyst exhibits excellent durability and good methanol‐tolerance. Detailed investigations demonstrate that a moderate content of Fe dopants can effectively increase the intrinsic activities, and the hybridization of graphene can enhance the reaction kinetics of ORR. The strategy proposed in this work gives an inspiration towards developing efficient noble‐metal‐free electrocatalysts for ORR.
Synopse der Naturgefahren für Köln
Authors: Schwarz Jochen , Maiwald Holger 
Published: January 2020

AbstractDie Synopse der Naturgefahren für die Stadt Köln hat sich als Musterbeispiel für die Betrachtung multipler Naturgefahren erwiesen. In verschiedenen Forschungsprojekten wird auf die im Rahmen des Deutschen Forschungsnetzes Naturkatastrophen (DFNK) vorgelegten Ergebnisse zurückgegriffen. Dabei werden zum Teil die gleichen Ansätze für die Bebauung, Einwirkung bzw. Korrelation zur Ermittlung der Verluste zugrunde gelegt. Der Beitrag spiegelt aus aktueller Sicht, welche Fortschritte im Bereich der Multi‐Hazard‐ und Risikobewertung erreicht wurden, wie sich diese in den Prognosen und Szenarien niederschlagen und nicht zuletzt, welcher Forschungsbedarf weiterhin abzuleiten ist. Im Vordergrund steht die Fragestellung, welche Konsequenzen sich aus der Detailaufnahme der betroffenen Gebiete und Bestandsbebauung ergeben. In diesem Zusammenhang kommen die von den Autoren entwickelten Verletzbarkeits‐ bzw. Schadensfunktionen zur Anwendung, die für die betrachteten Naturgefahren (Erdbeben, Sturm, Hochwasser) eine Prognose der zu erwartenden Verteilung der Schadensgrade und die Neubestimmung der Verluste ermöglichen. In Abhängigkeit von der Wiederkehrperiode und unter Berücksichtigung der aktuellen Werteentwicklung lassen sich infolge der mikroskaligen Gebäudebetrachtung qualitative und quantitative Veränderungen begründen.
Towards Germanium Layered Materials as Superior Negative Electrodes for Li‐, Na‐, and K‐Ion Batteries
Authors: Loaiza Laura C. , Monconduit Laure , Seznec Vincent 
Published: January 2020

AbstractThe germanium high theoretical capacity renders it as a promising anode material with 1384 mAh/g for Li (Li15Ge4) and 369 mAh/g for Na (NaGe) and K (KGe). Nevertheless, Ge suffers from volume variations due to alkali insertion, to mitigate this issue several strategies have been proposed. Among them the use of layered Ge‐based phases, obtained from the CaGe2 Zintl phase by topotactic deintercalation of Ca2+ to form the germanane (GeH)n. This last one has a particular morphology of Ge6 rings interconnected to form planes that buffers the volume changes and shortens the diffusion pathways. Here, we have studied the germanane alkali storage properties and 2150, 495 and 205 mAh/g of reversible capacity were obtained for Li, Na and K, respectively. These results indicate that germanane can store more alkali ions than the predicted phases, perform well at high rates and maintain a good capacity retention.
The effect of treatment delay on time‐to‐recovery in the presence of unobserved heterogeneity
Authors: van Geloven Nan , Balan Theodor A. , Putter Hein , le Cessie Saskia 
Published: January 2020

AbstractWe study the effect of delaying treatment in the presence of (unobserved) heterogeneity. In a homogeneous population and assuming a proportional treatment effect, a treatment delay period will result in notably lower cumulative recovery percentages. We show in theoretical scenarios using frailty models that if the population is heterogeneous, the effect of a delay period is much smaller. This can be explained by the selection process that is induced by the frailty. Patient groups that start treatment later have already undergone more selection. The marginal hazard ratio for the treatment will act differently in such a more homogeneous patient group. We further discuss modeling approaches for estimating the effect of treatment delay in the presence of heterogeneity, and compare their performance in a simulation study. The conventional Cox model that fails to account for heterogeneity overestimates the effect of treatment delay. Including interaction terms between treatment and starting time of treatment or between treatment and follow up time gave no improvement. Estimating a frailty term can improve the estimation, but is sensitive to misspecification of the frailty distribution. Therefore, multiple frailty distributions should be used and the results should be compared using the Akaike Information Criterion. Non‐parametric estimation of the cumulative recovery percentages can be considered if the dataset contains sufficient long term follow up for each of the delay strategies. The methods are demonstrated on a motivating application evaluating the effect of delaying the start of treatment with assisted reproductive techniques on time‐to‐pregnancy in couples with unexplained subfertility.
Microbial growth rates and local external mass transfer coefficients in a porous bed biofilm system measured by 19F magnetic resonance imaging of structure, oxygen concentration, and flow velocity
Authors: Simkins Jeffrey W. , Stewart Philip S. , Codd Sarah L. , Seymour Joseph D. 
Published: January 2020

Abstract19F nuclear magnetic resonance (NMR) oximetry and 1H NMR velocimetry were used to noninvasively map oxygen concentrations and hydrodynamics in space and time in a model packed bed biofilm system in the presence and absence of flow. The development of a local oxygen sink associated with a single gel bead inoculated with respiring Escherichia coli was analyzed with a phenomenological model to determine the specific growth rate of the bacteria in situ, returning a value (0.66 hr−1) that was close to that measured independently in planktonic culture (0.62 hr−1). The decay of oxygen concentration in and around the microbiologically active bead was delayed and slower in experiments conducted under continuous flow in comparison to no‐flow experiments. Concentration boundary layer thicknesses were determined and Sherwood numbers calculated to quantify external mass transfer resistance. Boundary layers were thicker in no‐flow experiments compared to experiments with flow. Whereas the oxygen concentration profile across a reactive biofilm particle was symmetric in no‐flow experiments, it was asymmetric with respect to flow direction in flow experiments with Sherwood numbers on the leading edge (Sh = 7) being larger than the trailing edge (Sh = 3.5). The magnitude of the experimental Sh was comparable to values predicted by a variety of correlations. These spatially resolved measurements of oxygen distribution in a geometrically complex model reveal in innovative detail the local coupling between microbial growth, oxygen consumption, and external mass transfer.