bluuebunny/crossref_metadata_2025 huggingface dataset:
Room temperature “optical nanodiamond hyperpolarizer”: Physics, design, and operation
Authors: Ajoy A. , Nazaryan R. , Druga E. , Liu K. , Aguilar A. , Han B. , Gierth M. , Oon J. T. , Safvati B. , Tsang R. , Walton J. H. , Suter D. , Meriles C. A. , Reimer J. A. , Pines A.
Published: February 2020

Dynamic Nuclear Polarization (DNP) is a powerful suite of techniques that deliver multifold signal enhancements in nuclear magnetic resonance (NMR) and MRI. The generated athermal spin states can also be exploited for quantum sensing and as probes for many-body physics. Typical DNP methods require the use of cryogens, large magnetic fields, and high power microwave excitation, which are expensive and unwieldy. Nanodiamond particles, rich in Nitrogen-Vacancy (NV) centers, have attracted attention as alternative DNP agents because they can potentially be optically hyperpolarized at room temperature. Here, unraveling new physics underlying an optical DNP mechanism first introduced by Ajoy et al. [Sci. Adv. 4, eaar5492 (2018)], we report the realization of a miniature “optical nanodiamond hyperpolarizer,” where 13C nuclei within the diamond particles are hyperpolarized via the NV centers. The device occupies a compact footprint and operates at room temperature. Instrumental requirements are very modest: low polarizing fields, low optical and microwave irradiation powers, and convenient frequency ranges that enable miniaturization. We obtain the best reported optical 13C hyperpolarization in diamond particles exceeding 720 times of the thermal 7 T value (0.86% bulk polarization), corresponding to a ten-million-fold gain in averaging time to detect them by NMR. In addition, the hyperpolarization signal can be background-suppressed by over two-orders of magnitude, retained for multiple-minute long periods at low fields, and deployed efficiently even to 13C enriched particles. Besides applications in quantum sensing and bright-contrast MRI imaging, this work opens possibilities for low-cost room-temperature DNP platforms that relay the 13C polarization to liquids in contact with the high surface-area particles.
Topology of the second-order constitutive model based on the Boltzmann–Curtiss kinetic equation for diatomic and polyatomic gases
Authors: Singh S. , Karchani A. , Sharma K. , Myong R. S.
Published: February 2020

The topological aspects of fluid flows have long been fascinating subjects in the study of the physics of fluids. In this study, the topology of the second-order Boltzmann–Curtiss constitutive model beyond the conventional Navier–Stokes–Fourier equations and Stokes’s hypothesis was investigated. In the case of velocity shear, the topology of the second-order constitutive model was shown to be governed by a simple algebraic form. The bulk viscosity ratio in diatomic and polyatomic gases was found to play an essential role in determining the type of topology: from an ellipse to a circle, to a parabola, and then finally to a hyperbola. The topology identified in the model has also been echoed in other branches of science, notably in the orbits of planets and comets and Dirac cones found in electronic band structures of two-dimensional materials. The ultimate origin of the existence of the topology was traced to the coupling of viscous stress and velocity gradient and its subtle interplay with the bulk viscosity ratio. In the case of compression and expansion, the topology of the second-order constitutive model was also found to be governed by a hyperbola. The trajectories of solutions of two representative flow problems—a force-driven Poiseuille gas flow and the inner structure of shock waves—were then plotted on the topology of the constitutive model, demonstrating the indispensable role of the topology of the constitutive model in fluid dynamics.
Valence states and the magnetism of Eu ions in Eu-doped GaN
Authors: Nunokawa Takumi , Fujiwara Yasufumi , Miyata Yusuke , Fujimura Norifumi , Sakurai Takahiro , Ohta Hitoshi , Masago Akira , Shinya Hikari , Fukushima Tetsuya , Sato Kazunori , Katayama-Yoshida Hiroshi
Published: February 2020

The relationship between the valence states of Eu ions in Eu-doped GaN and their magnetic properties is investigated by experiments and simulations. X-ray measurements have verified that the valence states of Eu ions can be controlled through growth temperature and codopants and that the highest concentration of divalent Eu ions is found in samples grown at 700°C by codoping with Si and O. According to our phenomenological analysis, magnetoresistance measurement implies the presence of Zener’s p–f exchange interaction. However, the magnetization dependence on an external magnetic field shows non-hysteretic sigmoidal curves in all the samples. Our simulations suggest that this is due to the formation of nanostructures of the magnetic impurities in the samples by spinodal decomposition.
Multiferroic and thermal expansion properties of metal-organic frameworks
Authors: Ma Yinina , Sun Young
Published: February 2020

As a prototype of organic–inorganic hybrid compounds, metal-organic frameworks (MOFs) have attracted enormous interest for their diverse physical and chemical properties. Recently, the magnetic and electric properties of MOFs have started to draw much attention. In particular, the coexistence of multiple orders (magnetic, electric, and elastic) in some MOFs makes them as emerging multiferroic materials. In terms of the strong and tunable ferroelectricity, the long-distance superexchange interaction, the order–disorder transition of hydrogen bonds in combination with the structural flexibility, and multiferroic MOFs represent a unique family beyond conventional inorganic multiferroics. This perspective provides a brief overview of recent progress in the field of multiferroic MOFs. First, the multiferroic MOFs reported so far are summarized and classified. Then, various cross coupling effects, i.e., the magnetic field control of electric polarization, electric field manipulation of magnetization, and pressure tuning of magnetic and electric properties, are described and discussed. In addition, a number of unusual phenomena such as the giant thermal expansion and quantum effects are introduced. Finally, some promising topics that have not yet been fully explored in multiferroic MOFs are proposed.
Magnetic pulses enable multidimensional optical spectroscopy of dark states
Authors: Oviedo-Casado Santiago , Šanda František , Hauer Jürgen , Prior Javier
Published: February 2020

The study and manipulation of low dipole moment quantum states have been challenging due to their inaccessibility by conventional spectroscopic techniques. Controlling the spin in such states requires unfeasible strong magnetic fields to overcome typical decoherence rates. However, the advent of terahertz technology and its application in magnetic pulses opens up a new scenario. In this article, we focus on an electron–hole pair model to demonstrate that it is possible to control the precession of the spins and to modify the transition rates to different spin states. Enhancing transitions from a bright state to a dark state with different spins means that the latter can be revealed by ordinary spectroscopy. We propose a modification of the standard two-dimensional spectroscopic scheme in which a three pulse sequence is encased in a magnetic pulse. Its role is to drive transitions between a bright and a dark spin state, making the latter susceptible to spectroscopic investigation.
Tunnel magnetocapacitance in Fe/MgF2 single nanogranular layered films
Authors: Msiska Robin , Honjo Shusaku , Asai Yuki , Arita Masashi , Tsurumaki-Fukuchi Atsushi , Takahashi Yasuo , Hoshino Norihisa , Akutagawa Tomoyuki , Kitakami Osamu , Fujioka Masaya , Nishii Junji , Kaiju Hideo
Published: February 2020

The tunnel magnetocapacitance (TMC) effect in two-dimensional single nanogranular layered Fe/MgF2 films is investigated both experimentally and theoretically. We measured the frequency dependence of TMC ratios in a frequency range of 20 Hz–1 MHz and discovered that TMC ratios strongly depend on the frequency, reaching a peak value at a specific frequency. We observe that the largest TMC ratios occur at lower frequencies and that TMC values steadily reduce with increasing frequency. Notably, we achieved a maximum TMC ratio of 1.45%, which is the largest low-field TMC ever reported for granular films. A combination of the Debye–Fröhlich (DF) model and the Julliere formula is used to fit the experimental data to theory, and an excellent agreement between the calculated values and the experimental data is obtained. To perfectly fit the experimental data, the conventional DF model is extended to a composite model in which three capacitors (with three different relaxation times) are introduced. Our findings will give further insights into the exact mechanism of the TMC effect in nanogranular films and will open broader opportunities for device applications, such as magnetic sensors and impedance tunable devices.
Energy storage oscillation of metallic glass induced by high-intensity elastic stimulation
Authors: Sohrabi S. , Li M. X. , Bai H. Y. , Ma J. , Wang W. H. , Greer A. L.
Published: February 2020

Thermomechanical processing of metallic glasses can, remarkably, induce significant changes in structure and properties, even when the imposed macroscopic strains are well within the elastic regime. The changes can take the glasses to higher-energy “rejuvenated” or lower-energy “aged” states, with rejuvenation being of particular interest as it improves their mechanical properties. It has generally been assumed that the induced property changes would evolve monotonically with the extent of processing. We show that with sufficiently intense ultrasonic elastic processing, the intrinsic structural competition between damage and repair facilitated by increased atomic mobility can lead to oscillatory energy storage. The uncovering of this behavior forces reconsideration about the range of energy states attainable in metallic glasses by elastic deformation and may provide opportunities.
Interlayer coupling in intrinsically magnetic bilayer ScO2 and NbN2
Authors: Guo Xiaoyan , Li Fangfang , Zhu Yu , Han Xiufeng , Yan Yu
Published: February 2020

Two-dimensional (2D) van der Waals (vdW) intrinsic magnets have been used to fabricate spin filter magnetic tunnel junctions and spin tunnel field-effect transistors, and the interlayer coupling of 2D vdW intrinsic magnets is of vital importance for obtaining high performance vdW spintronic devices based on 2D materials. In this work, we investigate the electronic structures and magnetic properties of bilayer ScO2 and NbN2 by using first principles calculations. It is found that AB stacking is the most preferred stacking order of bilayer ScO2 and NbN2. Furthermore, the ground state of AB-stacked bilayer ScO2 is a semiconductor with intralayer ferromagnetic (FM) and interlayer antiferromagnetic (AFM) couplings, and the magnetic moments are mainly provided by the pz orbits of the O atoms. In contrast, the ground state of AB-stacked bilayer NbN2 is a metal with intra- and inter-layer FM couplings, and the magnetic moments are mainly from the dz2 orbits of the Nb atoms. In particular, the interlayer AFM coupling of AB-stacked bilayer ScO2 is much larger than intralayer FM coupling due to the superposition of the spin-polarized pz orbits of the O atoms in adjacent layers. Compared to the strong interlayer AFM coupling of bilayer ScO2, the interlayer magnetic coupling of AB-stacked bilayer NbN2 is negligible because the spin-polarized dz2 orbits of the Nb atoms in adjacent layers do not overlap. Our results will benefit a deep understanding of the interlayer coupling of 2D vdW intrinsic magnets and exploring of high performance spintronic devices based on 2D vdW intrinsic magnets.
A full-dimensional ab initio intermolecular potential energy surface and ro-vibrational spectra for N2–HF and N2–DF
Authors: Liu Qiong , Huang Jing , Zhou Yanzi , Xie Daiqian
Published: February 2020

A full-dimensional ab initio intermolecular potential energy surface (IPES) is reported in this paper for van der Waals complex N2–HF. The calculations were performed by employing the explicitly correlated coupled cluster [CCSD (T)-F12a] method with the augmented correlation-consistent aug-cc-pVTZ basis set plus bond functions. The basis set superposition error was corrected by the full counterpoise procedure. About 55 000 ab initio points were calculated and then fitted by the permutation invariant polynomial neural network approach with a root-mean-square error of 0.433 cm−1. The potential energy surface features two equivalent linear minima with a well depth of 811.012 cm−1 separated by a barrier of 635.836 cm−1. The ro-vibrational energy levels for N2–HF and N2–DF were calculated based on the vibrationally averaged 4D IPESs with the radial discrete variable representation/angular finite basis representation method and Lanczos propagation algorithm. The calculated frequencies and the relative line intensities in the HF (DF) stretching band agree well with the available observed spectra. The theoretical band origins are all red shifted relative to the isolated HF (DF) molecule and reproduce the experimental values well. The results of ro-vibrational state calculations demonstrate the high accuracy of our new PES.
A reduced MHD model for ITG-NTM interplay
Authors: Frank J. , Agullo O. , Maget P. , Garbet X. , Dubuit N. , Muraglia M.
Published: February 2020

A six-field reduced-MHD model is derived for plasma dynamics. The new model describes coherently both ion temperature gradient (ITG) mode and tearing mode and includes neoclassical effects. The model allows the construction of an energylike quantity with a linear pressure contribution that is conserved except for dissipative, finite Larmor radius, and neoclassical terms. This model may be used to study the nonlinear interaction between ITG microturbulence and neoclassical tearing mode, which is responsible for large-scale magnetic islands in tokamaks, and opens the way to a coherent description of turbulent impurity transport in magnetic islands.
Nucleation and shape dynamics of model nematic tactoids around adhesive colloids
Authors: Ludwig Nicholas B. , Weirch Kimberly L. , Alster Eli , Witten Thomas A. , Gardel Margaret L. , Dasbiswas Kinjal , Vaikuntanathan Suriyanarayanan
Published: February 2020

Recent experiments have shown how nematically ordered tactoid shaped actin droplets can be reorganized and divided by the action of myosin molecular motors. In this paper, we consider how similar morphological changes can potentially be achieved under equilibrium conditions. Using simulations, both atomistic and continuum, and a simple macroscopic model, we explore how the nucleation dynamics, shape changes, and the final steady state of a nematic tactoid droplet can be modified by interactions with model adhesive colloids that mimic a myosin motor cluster. We show how tactoid reorganization may occur in an equilibrium colloidal-nematic setting. We then suggest based on the simple macroscopic model how the simulation models may be extended to potentially stabilize divided tactoids.
Design, modeling, and fabrication of a new compact perfect metamaterial X-band absorber
Authors: Asl Ahmed Nagy , Yousif Bedir , Al-zalabani Mahmoud
Published: February 2020

In this paper, a perfect metamaterial meander line absorber is designed, fabricated, and characterized by a waveguide measurement technique. The proposed metamaterial absorber of a double metal split ring resonator has a single-band absorption response in the microwave region. The characterization and analysis technique of the absorber illustrated a development in its bandwidth value, which minimizes both reflection and transmission coefficients for different upper metal lengths. Simulation and experimental results show that the absorber has a good perfect absorption in the frequency band between 8.5 GHz and 9 GHz. Moreover, the simulation results are in good agreement with the experimental measurements, which verify that this absorber can be used for the radar cross section and any electromagnetic compatibility at the X-band region.
Dynamics of phase separation of sheared inertialess binary mixtures
Authors: Chueh Chih-Che , Bertei Antonio , Mauri Roberto
Published: February 2020

When a viscous binary mixture subject to an applied shear flow is rapidly quenched into the unstable region of its phase diagram, the resulting phase separation is influenced by two competing effects. On one hand, nuclei of the minority phase tend to grow with a constant growth rate, while, on the other hand, they are stretched along the flow direction, forming thinner and thinner layered domains that eventually break. We simulate the dynamics of this system with a thermodynamics-based diffuse interface model, accounting for the full interplay between hydrodynamics (i.e., the Navier–Stokes equations) and species conservation (i.e., the Cahn–Hilliard equation) coupled via the Korteweg body-force. We show that periodic steady-state configurations with stable droplets are obtained for low capillary numbers while phase separation takes place along bands oriented in the direction of the flow in the case of strong shear because, in the long term, diffusion in the cross-flow direction prevails on the convective flow field. The dynamics of phase separation is highly non-linear and diverse even for inertialess flow, featuring multiple coalescence and breakups: although some typical time scaling for the characteristic droplet size in the flow and cross-flow directions can be obtained, the full evolution cannot be characterized only by the capillary number. The wide range of droplet morphologies predicted by the model, from round and elongated shapes to bands and hollow droplets, suggests interesting applications for manufacturing of polymers and soft materials.
Global analysis of LARP1 translation targets reveals tunable and dynamic features of 5′ TOP motifs
Authors: Philippe Lucas , van den Elzen Antonia M. G. , Watson Maegan J. , Thoreen Carson C.
Published: February 2020

Terminal oligopyrimidine (TOP) motifs are sequences at the 5′ ends of mRNAs that link their translation to the mTOR Complex 1 (mTORC1) nutrient-sensing signaling pathway. They are commonly regarded as discrete elements that reside on ∼100 mRNAs that mostly encode translation factors. However, the full spectrum of TOP sequences and their prevalence throughout the transcriptome remain unclear, primarily because of uncertainty over the mechanism that detects them. Here, we globally analyzed translation targets of La-related protein 1 (LARP1), an RNA-binding protein and mTORC1 effector that has been shown to repress TOP mRNA translation in a few specific cases. We establish that LARP1 is the primary translation regulator of mRNAs with classical TOP motifs genome-wide, and also that these motifs are extreme instances of a broader continuum of regulatory sequences. We identify the features of TOP sequences that determine their potency and quantify these as a metric that accurately predicts mTORC1/LARP1 regulation called a TOPscore. Analysis of TOPscores across the transcriptomes of 16 mammalian tissues defines a constitutive “core” set of TOP mRNAs, but also identifies tissue-specific TOP mRNAs produced via alternative transcription initiation sites. These results establish the central role of LARP1 in TOP mRNA regulation on a transcriptome scale and show how it connects mTORC1 to a tunable and dynamic program of gene expression that is tailored to specific biological contexts.
Intrinsically disordered protein RBM14 plays a role in generation of RNA:DNA hybrids at double-strand break sites
Authors: Jang Yumi , Elsayed Zeinab , Eki Rebeka , He Shuaixin , Du Kang-Ping , Abbas Tarek , Kai Mihoko
Published: February 2020

Accumulating evidence suggests participation of RNA-binding proteins with intrinsically disordered domains (IDPs) in the DNA damage response (DDR). These IDPs form liquid compartments at DNA damage sites in a poly(ADP ribose) (PAR)-dependent manner. However, it is greatly unknown how the IDPs are involved in DDR. We have shown previously that one of the IDPs RBM14 is required for the canonical nonhomologous end joining (cNHEJ). Here we show that RBM14 is recruited to DNA damage sites in a PARP- and RNA polymerase II (RNAPII)-dependent manner. Both KU and RBM14 are required for RNAPII-dependent generation of RNA:DNA hybrids at DNA damage sites. In fact, RBM14 binds to RNA:DNA hybrids. Furthermore, RNA:DNA hybrids and RNAPII are detected at gene-coding as well as at intergenic areas when double-strand breaks (DSBs) are induced. We propose that the cNHEJ pathway utilizes damage-induced transcription and intrinsically disordered protein RBM14 for efficient repair of DSBs.
Dynamics of life expectancy and life span equality
Authors: Aburto José Manuel , Villavicencio Francisco , Basellini Ugofilippo , Kjærgaard Søren , Vaupel James W.
Published: February 2020

Significance

Why life expectancy and life span equality have increased together is a question of scientific interest. Both measures are calculated for a calendar year and might not describe a cohort’s actual life course. Nonetheless, life expectancy provides a useful measure of average life spans, and life span equality gives insights into uncertainty about age at death. We show how patterns of change in life expectancy and life span equality are described by trajectories of mortality improvements over age and time. The strength of the relationship between life expectancy and life span equality is not coincidental but rather a result of progress in saving lives at specific ages: the more lives saved at the youngest ages, the stronger the relationship is.
Interferon lambda promotes immune dysregulation and tissue inflammation in TLR7-induced lupus
Authors: Goel Rishi R. , Wang Xinghao , O’Neil Liam J. , Nakabo Shuichiro , Hasneen Kowser , Gupta Sarthak , Wigerblad Gustaf , Blanco Luz P. , Kopp Jeffrey B. , Morasso Maria I. , Kotenko Sergei V. , Yu Zu-Xi , Carmona-Rivera Carmelo , Kaplan Mariana J.
Published: February 2020

Type III IFN lambdas (IFN-λ) have recently been described as important mediators of immune responses at barrier surfaces. However, their role in autoimmune diseases such as systemic lupus erythematosus (SLE), a condition characterized by aberrant type I IFN signaling, has not been determined. Here, we identify a nonredundant role for IFN-λ in immune dysregulation and tissue inflammation in a model of TLR7-induced lupus. IFN-λ protein is increased in murine lupus and IFN-λ receptor (Ifnlr1) deficiency significantly reduces immune cell activation and associated organ damage in the skin and kidneys without effects on autoantibody production. Single-cell RNA sequencing in mouse spleen and human peripheral blood revealed that only mouse neutrophils and human B cells are directly responsive to this cytokine. Rather, IFN-λ activates keratinocytes and mesangial cells to produce chemokines that induce immune cell recruitment and promote tissue inflammation. These data provide insights into the immunobiology of SLE and identify type III IFNs as important factors for tissue-specific pathology in this disease.
Algal photophysiology drives darkening and melt of the Greenland Ice Sheet
Authors: Williamson Christopher J. , Cook Joseph , Tedstone Andrew , Yallop Marian , McCutcheon Jenine , Poniecka Ewa , Campbell Douglas , Irvine-Fynn Tristram , McQuaid James , Tranter Martyn , Perkins Rupert , Anesio Alexandre
Published: February 2020

Blooms of Zygnematophycean “glacier algae” lower the bare ice albedo of the Greenland Ice Sheet (GrIS), amplifying summer energy absorption at the ice surface and enhancing meltwater runoff from the largest cryospheric contributor to contemporary sea-level rise. Here, we provide a step change in current understanding of algal-driven ice sheet darkening through quantification of the photophysiological mechanisms that allow glacier algae to thrive on and darken the bare ice surface. Significant secondary phenolic pigmentation (11 times the cellular content of chlorophyll
a
) enables glacier algae to tolerate extreme irradiance (up to ∼4,000 µmol photons⋅m
−2
⋅s
−1
) while simultaneously repurposing captured ultraviolet and short-wave radiation for melt generation. Total cellular energy absorption is increased 50-fold by phenolic pigmentation, while glacier algal chloroplasts positioned beneath shading pigments remain low-light–adapted (
E

k

∼46 µmol photons⋅m
−2
⋅s
−1
) and dependent upon typical nonphotochemical quenching mechanisms for photoregulation. On the GrIS, glacier algae direct only ∼1 to 2.4% of incident energy to photochemistry versus 48 to 65% to ice surface melting, contributing an additional ∼1.86 cm water equivalent surface melt per day in patches of high algal abundance (∼10
4
cells⋅mL
−1
). At the regional scale, surface darkening is driven by the direct and indirect impacts of glacier algae on ice albedo, with a significant negative relationship between broadband albedo (Moderate Resolution Imaging Spectroradiometer [MODIS]) and glacier algal biomass (
R
2
= 0.75,
n
= 149), indicating that up to 75% of the variability in albedo across the southwestern GrIS may be attributable to the presence of glacier algae.
Dramatic dietary shift maintains sequestered toxins in chemically defended snakes
Authors: Yoshida Tatsuya , Ujiie Rinako , Savitzky Alan H. , Jono Teppei , Inoue Takato , Yoshinaga Naoko , Aburaya Shunsuke , Aoki Wataru , Takeuchi Hirohiko , Ding Li , Chen Qin , Cao Chengquan , Tsai Tein-Shun , Silva Anslem de , Mahaulpatha Dharshani , Nguyen Tao Thien , Tang Yezhong , Mori Naoki , Mori Akira
Published: February 2020

Significance

Animals protected by sequestered toxins must employ an alternative source of defensive chemicals when a shift in diet evolves. Snakes of the genus
Rhabdophis
possess defensive glands that store powerful defensive toxins known as bufadienolides. The ancestral prey of
Rhabdophis
consists of anuran amphibians, including toads (Bufonidae) that are the source of sequestered bufadienolides. However, members of a derived clade of
Rhabdophis
consume nontoxic earthworms as their primary prey, yet their integumentary glands still contain bufadienolides. We demonstrate that snakes in the worm-eating clade obtain their defensive toxins primarily by consuming larval fireflies. Our finding represents a remarkable evolutionary example in which a shift from vertebrate to nonvertebrate prey provides the same chemical class of sequestered defensive toxins.
Underactuated fluidic control of a continuous multistable membrane
Authors: Peretz Ofek , Mishra Anand K. , Shepherd Robert F. , Gat Amir D.
Published: February 2020

This work addresses the challenge of underactuated pattern generation in continuous multistable structures. The examined configuration is a slender membrane which can concurrently sustain two different equilibria states, separated by transition regions, and is actuated by a viscous fluid. We first demonstrate the formation and motion of a single transition region and then sequencing of several such moving transition regions to achieve arbitrary patterns by controlling the inlet pressure of the actuating fluid. Finally, we show that nonuniform membrane properties, along with transient dynamics of the fluid, can be leveraged to directly snap through any segment of the membrane.
Pinching a glass reveals key properties of its soft spots
Authors: Rainone Corrado , Bouchbinder Eran , Lerner Edan
Published: February 2020

Significance

Glasses form when liquids are quickly cooled. Many of the properties of glasses are universal—i.e., independent of their composition and the liquid-phase temperature

T

p

from which they were cooled. One such property is the existence of noncrystalline soft vibrational excitations, which are highly localized in space and follow a universal vibrational frequency distribution, with a nonuniversal coefficient. We show that pinching glasses—i.e., applying local force perturbations to them—reveals dramatic variability in the physics of this coefficient with

T

p

. In particular, it reveals how the number of noncrystalline soft vibrational excitations, their size, and typical degree of softness vary with

T

p

, having major implications for the behavior of glasses in a wide variety of situations.
Evaluation of a concerted vs. sequential oxygen activation mechanism in α-ketoglutarate–dependent nonheme ferrous enzymes
Authors: Goudarzi Serra , Iyer Shyam R. , Babicz Jeffrey T. , Yan James J. , Peters Günther H. J. , Christensen Hans E. M. , Hedman Britt , Hodgson Keith O. , Solomon Edward I.
Published: February 2020

Significance

Many iron-dependent enzymes utilize molecular oxygen to functionalize inert C–H bonds in biology. Nonheme ferrous enzymes perform these reactions by reducing dioxygen, often in the presence of a sacrificial electron donor, to form a reactive intermediate that converts substrate to product. In α-ketoglutarate (αKG)–dependent enzymes, there has been discussion on the necessity of substrate prebinding to the αKG-bound ferrous center for productive chemistry. This study demonstrates that, when substrate is not prebound to the enzyme, the species generated in the reaction with dioxygen is not competent to perform hydrogen atom abstraction from the substrate. In contrast, when both cosubstrates are prebound to the enzyme, efficient coupling between dioxygen reduction and substrate oxidation is observed, leading to productive chemistry.
Photoperiod and temperature separately regulate nymphal development through JH and insulin/TOR signaling pathways in an insect
Authors: Miki Taiki , Shinohara Tsugumichi , Chafino Silvia , Noji Sumihare , Tomioka Kenji
Published: February 2020

Insects living in the temperate zone enter a physiological state of arrested or slowed development to overcome an adverse season, such as winter. Developmental arrest, called diapause, occurs at a species-specific developmental stage, and embryonic and pupal diapauses have been extensively studied in mostly holometabolous insects. Some other insects overwinter in the nymphal stage with slow growth for which the mechanism is poorly understood. Here, we show that this nymphal period of slow growth is regulated by temperature and photoperiod through separate pathways in the cricket
Modicogryllus siamensis
. The former regulates the growth rate, at least in part, through the insulin / target of rapamycin (TOR) signaling pathway. Lower temperature down-regulates the expression of
insulin
-like peptide
(
Ms’Ilp
) and
Target of rapamycin
(
Ms’Tor
) genes to slow down the growth rate without affecting the number of molts. The latter regulates the number of molts independent of temperature. Short days increase the number of molts through activation of the juvenile hormone (JH) pathway and down-regulation of
myoglianin
(
Ms’myo
), a member of the TGFβ family, which induces adult metamorphosis. In contrast, long days regulate
Ms’myo
expression to increase during the fifth to sixth instar to initiate adult metamorphosis. When
Ms’myo
expression is suppressed,
juvenile hormone O-methyl transferase
(
Ms’jhamt
) was up-regulated and increased molts to prolong the nymphal period even under long-day conditions. The present findings suggested that the photoperiod regulated
Ms’myo
, and the JH signaling pathway and the temperature-controlled insulin/TOR pathway cooperated to regulate nymphal development for overwintering to achieve seasonal adaptation of the life cycle in
M. siamensis
.
Stearoyl-CoA desaturase-1 impairs the reparative properties of macrophages and microglia in the brain
Authors: Bogie Jeroen F.J. , Grajchen Elien , Wouters Elien , Corrales Aida Garcia , Dierckx Tess , Vanherle Sam , Mailleux Jo , Gervois Pascal , Wolfs Esther , Dehairs Jonas , Van Broeckhoven Jana , Bowman Andrew P. , Lambrichts Ivo , Gustafsson Jan-Åke , Remaley Alan T. , Mulder Monique , Swinnen Johannes V. , Haidar Mansour , Ellis Shane R. , Ntambi James M. , Zelcer Noam , Hendriks Jerome J.A.
Published: February 2020

Failure of remyelination underlies the progressive nature of demyelinating diseases such as multiple sclerosis. Macrophages and microglia are crucially involved in the formation and repair of demyelinated lesions. Here we show that myelin uptake temporarily skewed these phagocytes toward a disease-resolving phenotype, while sustained intracellular accumulation of myelin induced a lesion-promoting phenotype. This phenotypic shift was controlled by stearoyl-CoA desaturase-1 (SCD1), an enzyme responsible for the desaturation of saturated fatty acids. Monounsaturated fatty acids generated by SCD1 reduced the surface abundance of the cholesterol efflux transporter ABCA1, which in turn promoted lipid accumulation and induced an inflammatory phagocyte phenotype. Pharmacological inhibition or phagocyte-specific deficiency of Scd1 accelerated remyelination ex vivo and in vivo. These findings identify SCD1 as a novel therapeutic target to promote remyelination.
Final report, on-going key comparison BIPM.QM-K1, ozone at ambient level, comparison with JRC, July 2019
Authors: Viallon Joële , Idrees Faraz , Moussay Philippe , Wielgosz Robert , Lagler Friedrich
Published: February 2020

As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone standard of the European Commission maintained by the Joint Research Centre (JRC) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount-of-substance fraction range from 0 nmol/mol to 500 nmol/mol.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Multiscale simulations of singlet and triplet exciton dynamics in energetically disordered molecular systems based on many-body Green's functions theory
Authors: Wehner Jens , Baumeier Björn
Published: February 2020

We present a multiscale model based on many-body Green’s functions theory in the GW approximation and the Bethe–Salpeter equation (GW-BSE) for the simulation of singlet and triplet exciton transport in molecular materials. Dynamics of coupled electron–hole pairs are modeled as a sequence of incoherent tunneling and decay events in a disordered morphology obtained at room temperature from molecular dynamics. The ingredients of the rates associated to the events, i.e. reorganization energies, site energies, lifetimes, and coupling elements, are determined from a combination of GW-BSE and classical polarizable force field techniques. Kinetic Monte Carlo simulations are then employed to evaluate dynamical properties such as the excitonic diffusion tensor and diffusion lengths. Using DCV5T-Me(3,3), a crystalline organic semiconductor, we demonstrate how this multiscale approach provides insight into the fundamental factors driving the transport processes. Comparing the results obtained via different calculation models, we investigate in particular the effects of charge-transfer mediated high exciton coupling and the influence of internal site energy disorder due to conformational variations. We show that a small number of high coupling elements indicative of delocalized exciton states does not impact the overall dynamics perceptively. Molecules with energies in the tail of the excitonic density of states dominate singlet decay, independent of the level of disorder taken into account in the simulation. Overall, our approach yields singlet diffusion lengths on the order of 10 nm as expected for energetically disordered molecular materials.
Monte Carlo basin bifurcation analysis
Authors: Gelbrecht Maximilian , Kurths Jürgen , Hellmann Frank
Published: February 2020

Many high-dimensional complex systems exhibit an enormously complex landscape of possible asymptotic states. Here, we present a numerical approach geared towards analyzing such systems. It is situated between the classical analysis with macroscopic order parameters and a more thorough, detailed bifurcation analysis. With our machine learning method, based on random sampling and clustering methods, we are able to characterize the different asymptotic states or classes thereof and even their basins of attraction. In order to do this, suitable, easy to compute, statistics of trajectories with randomly generated initial conditions and parameters are clustered by an algorithm such as DBSCAN. Due to its modular and flexible nature, our method has a wide range of possible applications in many disciplines. While typical applications are oscillator networks, it is not limited only to ordinary differential equation systems, every complex system yielding trajectories, such as maps or agent-based models, can be analyzed, as we show by applying it the Dodds–Watts model, a generalized SIRS-model, modeling social and biological contagion. A second order Kuramoto model, used, e.g. to investigate power grid dynamics, and a Stuart–Landau oscillator network, each exhibiting a complex multistable regime, are shown as well. The method is available to use as a package for the Julia language.
Quantum mechanical current-to-voltage conversion with quantum Hall resistance array
Authors: Chae Dong-Hun , Kim Mun-Seog , Kim Wan-Seop , Oe Takehiko , Kaneko Nobu-Hisa
Published: February 2020

Accurate measurement of the electric current requires a stable and calculable resistor for an ideal current-to-voltage conversion. However, the temporal resistance drift of a physical resistor is unavoidable, unlike the quantum Hall resistance directly linked to the Planck constant h and the elementary charge e. Lack of an invariant high-resistance leads to a challenge in making small-current measurements below 1 µA with an uncertainty better than one part in 106. In this work, we demonstrate a current-to-voltage conversion in the range from a few nano amps to one microamp with an invariant quantized Hall array resistance. The converted voltage is directly compared with the Josephson voltage reference in the framework of Ohm’s law. Markedly distinct from the classical conversion, which relies on an artifact resistance reference, this current-to-voltage conversion does not demand timely resistance calibrations. It improves the precision of current measurement down to 8  ×  10−8 at 1 µA.
Small-scale water deficits after wildfires create long-lasting ecological impacts
Authors: O’Connor Rory C , Germino Matthew J , Barnard David M , Andrews Caitlin M , Bradford John B , Pilliod David S , Arkle Robert S , Shriver Robert K
Published: February 2020

Ecological droughts are deficits in soil–water availability that induce threshold-like ecosystem responses, such as causing altered or degraded plant-community conditions, which can be exceedingly difficult to reverse. However, ‘ecological drought’ can be difficult to define, let alone to quantify, especially at spatial and temporal scales relevant to land managers. This is despite a growing need to integrate drought-related factors into management decisions as climate changes result in precipitation instability in many semi-arid ecosystems. We asked whether success in restoration seedings of the foundational species big sagebrush (Artemisia tridentata) was related to estimated water deficit, using the SoilWat2 model and data from >600 plots located in previously burned areas in the western United States. Water deficit was characterized by: (1) the standardized precipitation-evapotranspiration index (SPEI), a coarse-scale drought index, and (2) the number of days with wet and warm conditions in the near-surface soil, where seeds and seedlings germinate and emerge (i.e. days with 0–5 cm deep soil water potential >−2.5 MPa and temperature above 0 °C). SPEI, a widely used drought index, was not predictive of whether sagebrush had reestablished. In contrast, wet-warm days elicited a critical drought threshold response, with successfully reestablished sites having experienced seven more wet-warm days than unsuccessful sites during the first March following summer wildfire and restoration. Thus, seemingly small-scale and short-term changes in water availability and temperature can contribute to major ecosystem shifts, as many of these sites remained shrubless two decades later. These findings help clarify the definition of ecological drought for a foundational species and its imperiled semi-arid ecosystem. Drought is well known to affect the occurrence of wildfires, but drought in the year(s) after fire can determine whether fire causes long-lasting, negative impacts on ecosystems.
Inferring CO2 fertilization effect based on global monitoring land-atmosphere exchange with a theoretical model
Authors: Ueyama Masahito , Ichii Kazuhito , Kobayashi Hideki , Kumagai Tomo’omi , Beringer Jason , Merbold Lutz , Euskirchen Eugénie S , Hirano Takashi , Marchesini Luca Belelli , Baldocchi Dennis , Saitoh Taku M , Mizoguchi Yasuko , Ono Keisuke , Kim Joon , Varlagin Andrej , Kang Minseok , Shimizu Takanori , Kosugi Yoshiko , Bret-Harte M Syndonia , Machimura Takashi , Matsuura Yojiro , Ohta Takeshi , Takagi Kentaro , Takanashi Satoru , Yasuda Yukio
Published: February 2020

Rising atmospheric CO2 concentration ([CO2]) enhances photosynthesis and reduces transpiration at the leaf, ecosystem, and global scale via the CO2 fertilization effect. The CO2 fertilization effect is among the most important processes for predicting the terrestrial carbon budget and future climate, yet it has been elusive to quantify. For evaluating the CO2 fertilization effect on land photosynthesis and transpiration, we developed a technique that isolated this effect from other confounding effects, such as changes in climate, using a noisy time series of observed land-atmosphere CO2 and water vapor exchange. Here, we evaluate the magnitude of this effect from 2000 to 2014 globally based on constraint optimization of gross primary productivity (GPP) and evapotranspiration in a canopy photosynthesis model over 104 global eddy-covariance stations. We found a consistent increase of GPP (0.138 ± 0.007% ppm−1; percentile per rising ppm of [CO2]) and a concomitant decrease in transpiration (−0.073% ± 0.006% ppm−1) due to rising [CO2]. Enhanced GPP from CO2 fertilization after the baseline year 2000 is, on average, 1.2% of global GPP, 12.4 g C m−2 yr−1 or 1.8 Pg C yr−1 at the years from 2001 to 2014. Our result demonstrates that the current increase in [CO2] could potentially explain the recent land CO2 sink at the global scale.
Absorbent Properties of Polystyrene with Closed Outer Structure in Case of Failure of the External Surface of the Board
Authors: Pilný Ondřej , Kalousek Lubor
Published: February 2020

Thermal insulation is an integral part of almost all modern buildings. An important aspect in this process is the elimination of thermal bridges and insulation of all structures which are exposed to adverse environmental conditions. We are increasingly encountering thermal insulation solutions for elements that have been neglected in the past. One of these constructions is the substructure, which means not only the foundations, but underground floors and plinth. These constructions must be insulated with a material which not only has suitable thermal-insulating properties, but also has to withstand the effects of moisture in the long term. Nowadays, expanded polystyrene with a closed outer structure has become one of the most commonly used thermal insulators for these purposes. However, it is clear that, when built-in, the outer structure of the envelope is often damaged. This is often neglected phenomenon, which has a negative effect in the amount of diffusion flow and moisture propagation in the material. This paper describes a laboratory experiment, in which the outer structure of the EPS samples was broken in various ways. The samples were then fully immersed in water, changes in mass and volume absorbency over time were recorded and results were reciprocally compared.
Diagnostics of Flat Roofs with Flexible Sheets for Waterproofing
Authors: Šutliak Stanislav , Plachý Jan
Published: February 2020

This paper deals with diagnostics of flat roofs with flexible sheets for waterproofing (membrane). The diagnostics is focused on defects and water tightness of membrane. The roof is one of the building’s most important building envelope. In case of defect, the other layers of the roof, including the structure frame, are degraded. The introduction gives an overview of individual methods and their division. The following part describes advantages and drawbacks of the individual methods. The next part is focused on the following type of test - High Voltage Membrane Testing. The test is described in detail, including the Conductive detection membrane, which was developed specifically for this method. This test, in combination with other methods, seems optimal, but it is most reliable to prevent possible defects by following technological procedures.
Secondary Raw Materials in Construction
Authors: Smolka Radim , Sobotka Jindřich
Published: February 2020

The paper describes and evaluates the use of secondary materials in construction details of buildings, primarily in the area of flat roofs. The roofs have a large number of technologies that are necessary for the smooth and healthy use of buildings according to current standards. We are currently discussing the take-back of PET bottles in the Czech Republic. New materials must meet specified parameters. Not only thermal, but also hygienic and fire-fighting. Primarily failures of roof structures are problematic parts during repairs.
Surface Temperature of Flat Roofs with Waterproofing Polymer Membranes
Authors: Plachý Jan , Vysoká Jana
Published: February 2020

This paper deals with the problematics of the surface temperature of flat roofs, where the waterproofing layer is used as polymeric waterproofing membrane of softened PVC. Currently, it is possible to encounter defects on flat roofs due to the high surface temperature of the waterproofing layer. The consequence of such a high surface temperature is, for example, the sublimation of the thermal insulation of the foam polystyrene. The paper focuses on the influence of the color of the plasticized PVC membrane on the surface temperature. The aim of this paper is to determine the maximum surface temperature of a polymeric PVC membranes in the dependence on color on the basis of experimental measurements and furthermore, to determine the maximum temperature on the surface of the thermal insulation under PVC polymeric membrane. Measurements were taken during a warm summer day. Used samples were represented by polymeric membranes in green, gray, red and brown colors. Mineral wool was used as a substrate under the polymeric membrane.
Mid-Rise Atrium Residential Houses - Domain of Comfort
Authors: Maltseva Irina , Kaganovich Natalia , Tkachuk Konstantin
Published: February 2020

The paper discusses the role of a natural landscape in an industrial city, the harmonious interaction of an architectural object and the environment in creating a unified eco-architectural space. The authors focus on the typological aspect of residential architecture development, the feasibility of introducing low-rise complex development in the urban environment, suggesting the use of a morphologically autonomous category of urban villas as a type of residential building. The paper considers the advantages of a sustainable and presently relevant spatial archetype – an atrium – and its inclusion in the structure of a residential building and the eco-technical direction of its use along with separate engineering and technical solutions within the concept of energy saving. As an example, a low-rise residential complex project of an ‘urban apartment villa’ typological structure is considered, with the use of a multi-comfortable house system and the atrium principle of internal space organization in order to create an eco-friendly residential environment in the context of urban development and natural landscape.