bluuebunny/crossref_metadata_2025 huggingface dataset:
Component properties and mutual orbit of binary main-belt comet 288P/(300163) 2006 VW139
Authors: Agarwal J. , Kim Y. , Jewitt D. , Mutchler M. , Weaver H. , Larson S.
Published: September 2020

Context. The binary asteroid 288P/(300163) is unusual both for its combination of wide-separation and high mass ratio and for its comet-like activity. It is not currently known whether there is a causal connection between the activity and the unusual orbit or if instead the activity helped to overcome a strong detection bias against such sub-arcsecond systems.

Aims. We aim to find observational constraints discriminating between possible formation scenarios and to characterise the physical properties of the system components.

Methods. We measured the component separation and brightness using point spread function fitting to high-resolution Hubble Space Telescope/Wide Field Camera 3 images from 25 epochs between 2011 and 2020. We constrained component sizes and shapes from the photometry, and we fitted a Keplerian orbit to the separation as a function of time.

Results. Approximating the components A and B as prolate spheroids with semi-axis lengths a < b and assuming a geometric albedo of 0.07, we find aA ≤ 0.6 km, bA ≥ 1.4 km, aB ≤ 0.5 km, and bB ≥ 0.8 km. We find indications that the dust production may have concentrated around B and that the mutual orbital period may have changed by 1–2 days during the 2016 perihelion passage. Orbit solutions have semi-major axes in the range of (105–109) km, eccentricities between 0.41 and 0.51, and periods of (117.3–117.5) days pre-perihelion and (118.5–119.5) days post-perihelion, corresponding to system masses in the range of (6.67–7.23) × 1012 kg. The mutual and heliocentric orbit planes are roughly aligned.

Conclusions. Based on the orbit alignment, we infer that spin-up of the precursor by the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect led to the formation of the binary system. We disfavour (but cannot exclude) a scenario of very recent formation where activity was directly triggered by the break-up, because our data support a scenario with a single active component.
SDSS J1004+4112: the case for a galaxy cluster dominated by primordial black holes
Authors: Hawkins M. R. S.
Published: September 2020

Aims. This paper is aimed at providing a plausible explanation for the large amplitude microlensing events observed in the cluster-lensed quasar system, SDSS J1004+4112. The microlensed quasar images appear to lie well clear of the stellar population of the cluster, raising the possibility that the cluster dark matter is composed of compact bodies that are responsible for the observed microlensing.

Methods. We established the exact structure of the difference light curves attributed to microlensing from photometric monitoring programmes in the literature. We showed, based on measurements of surface brightness, that the probability of microlensing by stars in the cluster is negligible. We relaxed our initial assumption that the cluster dark matter takes the form of smoothly distributed particles and we hypothesized that it is made up of compact bodies. We then used computer simulations of the resulting magnification pattern to estimate the probability of microlensing.

Results. Our results show that for a range of values for source size and lens mass, the large microlensing amplitude that is observed is consistent with the statistics obtained from the simulations.

Conclusions. We conclude that providing the assumption of smoothly distributed dark matter is relaxed, the observed large amplitude microlensing can be accounted for by assuming that the cluster’s dark matter is in the form of compact bodies of solar mass. We further conclude that the most plausible identification of these bodies is that of primordial black holes.
A perfect power-law spectrum even at the highest frequencies: The Toothbrush relic
Authors: Rajpurohit K. , Vazza F. , Hoeft M. , Loi F. , Beck R. , Vacca V. , Kierdorf M. , van Weeren R. J. , Wittor D. , Govoni F. , Murgia M. , Riseley C. J. , Locatelli N. , Drabent A. , Bonnassieux E.
Published: September 2020

Radio relics trace shock fronts generated in the intracluster medium (ICM) during cluster mergers. The particle acceleration mechanism at the shock fronts is not yet completely understood. We observed the Toothbrush relic with the Effelsberg and Sardinia Radio Telescope at 14.25 GHz and 18.6 GHz, respectively. Unlike previously claimed, the integrated spectrum of the relic closely follows a power law over almost three orders of magnitude in frequency, with a spectral index ofα58 MHz18.6 GHz= −1.16 ± 0.03. Our finding is consistent with a power-law injection spectrum, as predicted by diffusive shock acceleration theory. The result suggests that there is only little magnetic field strength evolution downstream of the shock. From the lack of spectral steepening, we find that either the Sunyaev–Zeldovich decrement produced by the pressure jump is less extended than ∼600 kpc along the line of sight or, conversely, that the relic is located far behind in the cluster. For the first time, we detect linearly polarized emission from the “brush” at 18.6 GHz. Compared to 8.3 GHz, the degree of polarization across the brush increases at 18.6 GHz, suggesting a strong Faraday depolarization toward lower frequencies. The observed depolarization is consistent with an intervening magnetized screen that arises from the dense ICM containing turbulent magnetic fields. The depolarization, corresponding to a standard deviation of the rotation measures as high asσRM = 212 ± 23 rad m−2, suggests that the brush is located in or behind the ICM. Our findings indicate that the Toothbrush relic can be consistently explained by the standard scenario for relic formation.
Akute Inversio uteri puerperalis: Eine Falldarstellung
Authors: Osmanlıoğlu Şeyma
Published: September 2020

Die puerperale Uterusinversion ist eine seltene aber lebensbedrohliche geburtshilfliche Komplikation. Nicht erkannt kann es zu schweren Blutungen und Schock bis hin zum mütterlichen Tod führen. Eine manuelle Reposition unter Vollnarkose ist meistens erfolgreich. Bei resistenten Inversionen kann eine Korrektur per Laparotomie hinzugezogen werden. In jedem Fall können die Mortalität und Morbidität durch rechtzeitige Erkennung und zügige Reposition vermindert werden. Daher sollten regelmäßige praktische Übungen zur Erkennung und Behandlung der akuten uterinen Inversion, wie auch andere geburtshilfliche Notfälle im Rahmen der Facharztausbildung erfolgen. Wir berichten über eine 31-jährige II. Gravida 0. Para in der 39+4. Schwangerschaftswoche (SSW), bei der eine akute Inversio uteri dritten Grades nach einer spontanen Entbindung aufgetreten war, die bei frustraner vaginaler Reposition per Laparotomie in Intubationsnarkose reponiert wurde.
DBS Assay with LC-MS/MS for the Determination of Idelalisib, A Selective PI3K-δ Inhibitor in Mice Blood and Its Application to a Pharmacokinetic Study
Authors: Tripathy Harsha K. , Manju Nair S.V. , Dittakavi Sreekanth , Zakkula Ashok , Mullangi Ramesh
Published: September 2020

Idelalisib is a selective and second-generation PI3K-δ inhibitor, approved for the treatment of non-Hodgkin lymphoma and chronic lymphocytic leukemia. In this paper, we present a fully validated dried blood spot (DBS) method for the quantitation of idelalisib from mice blood using an LC-MS/MS, which was operated under multiple reaction monitoring mode. To the punched DBS discs, acidified methanol enriched with internal standard (IS; larotrectinib) was added and extracted using tert-butyl methyl ether as an extraction solvent with sonication. Chromatographic separation of idelalisib and the IS was achieved on an Atlantis dC18 column using a mixture of 10 mM ammonium formate:acetonitrile (25:75, v/v). The flow-rate and injection volume were 0.80 mL/min and 2.0 µL, respectively. Idelalisib and the IS were eluted at ~0.98 and 0.93 min, respectively and the total run time was 2.00 min. Idelalisib and the IS were analyzed using positive ion scan mode and parent-daughter mass to charge ion (m/z) transition of 416.1→176.1 and 429.1→342.1, respectively was used for the quantitation. The calibration range was 1.01−4 797 ng/mL. No matrix effect and carry over were observed. Haematocrit did not influence DBS idelalisib concentrations. All the validation parameters met the acceptance criteria. The applicability of the validated method was shown in a mice pharmacokinetic study.
Die Behandlung der avaskulären Kahnbeinpseudarthrose: gefäßgestielter Knochenspan vom Beckenkamm oder vom medialen Femurkondyl?
Authors: Kastenberger Tobias , Kaiser Peter , Bode Simone , Horling Lukas , Schmidle Gernot , Arora Rohit
Published: September 2020

Die Behandlung von Kahnbeinpseudarthrosen ist nach wie vor eine Herausforderung für den behandelnden Handchirurgen – im Speziellen bei avaskulären, proximalen Kahnbeinpseudarthrosen oder vorangegangenen fehlgeschlagenen Operationen. Unterschiedliche operative Verfahren wurden etabliert und basieren auf der Rekonstruktion der korrekten Anatomie des Kahnbeins, welche einerseits Stabilität bietet und andererseits eine ausreichende Durchblutung wiederherstellt. Das Behandlungsspektrum reicht von avaskulären bis hin zu freien, gefäßgestielten Spaninterponaten. Die beiden am häufigsten verwendeten freien vaskularisierten Knochenspäne stammen vom Beckenkamm und vom medialen Femurkondyl. Der Femurkondylenspan zeigt eine konstantere Gefäßanatomie, geringere Hebemorbidität und höherer Heilungsrate im Vergleich zum Beckenkammspan. Zudem ist der Span technisch einfacher zu heben und kann sowohl als kortikospongiöser, wie auch osteochondraler Span gehoben werden. In Summe der Vorteile kommen wir zu dem Schluss, dass die Versorgung der Kahnbeinpseudarthrose bei avaskulärem proximalen Pol mittels gefäßgestieltem Femurkondylenspan die Methode unserer Wahl ist.
Quantitative Magnetic Resonance Imaging of Cortical and Trabecular Bone
Authors: Jerban Saeed , Ma Yajun , Wei Zhao , Jang Hyungseok , Chang Eric Y. , Du Jiang
Published: September 2020

Bone is a composite material consisting of mineral, organic matrix, and water. Water in bone can be categorized as bound water (BW), which is bound to bone mineral and organic matrix, or as pore water (PW), which resides in Haversian canals as well as in lacunae and canaliculi. Bone is generally classified into two types: cortical bone and trabecular bone. Cortical bone is much denser than trabecular bone that is surrounded by marrow and fat. Magnetic resonance (MR) imaging has been increasingly used for noninvasive assessment of both cortical bone and trabecular bone. Bone typically appears as a signal void with conventional MR sequences because of its short T2*. Ultrashort echo time (UTE) sequences with echo times 100 to 1,000 times shorter than those of conventional sequences allow direct imaging of BW and PW in bone. This article summarizes several quantitative MR techniques recently developed for bone evaluation. Specifically, we discuss the use of UTE and adiabatic inversion recovery prepared UTE sequences to quantify BW and PW, UTE magnetization transfer sequences to quantify collagen backbone protons, UTE quantitative susceptibility mapping sequences to assess bone mineral, and conventional sequences for high-resolution imaging of PW as well as the evaluation of trabecular bone architecture.
The Effect of Small Size Uterine Fibroids on Pregnancy Outcomes in High-risk Pregnancies
Authors: Cagan Murat , Tanacan Atakan , Donmez Hanife Guler , Fadiloglu Erdem , Unal Canan , Beksac Mehmet Sinan
Published: September 2020

Objective To evaluate the obstetric outcomes of singleton high-risk pregnancies with a small size uterine fibroid.

Methods This retrospective cohort study was conducted among 172 high-risk pregnant women who were followed-up by a single surgeon between 2016 and 2019. Pregnant women with preconceptionally diagnosed small size (< 5 cm) single uterine fibroids (n = 25) were compared with pregnant women without uterine fibroids (n = 147) in terms of obstetric outcomes.

Results There was no statistically significant difference between the groups in terms of adverse pregnancy outcomes. The size of the fibroids was increased in 60% of the cases, and the growth percentage of the fibroids was 25% during pregnancy. Intrapartum and short-term complication was not observed in women who underwent cesarean myomectomy.

Conclusion Small size uterine fibroids seem to have no adverse effect on pregnancy outcomes even in high-risk pregnancies, and cesarean myomectomy may be safely performed in properly selected cases.
SARS-CoV-2 and Pregnancy: A Review of the Facts
Authors: Czeresnia Ricardo Mamber , Trad Ayssa Teles Abrao , Britto Ingrid Schwach Werneck , Negrini Romulo , Nomura Marcelo Luís , Pires Pedro , Costa Fabricio da Silva , Nomura Roseli Mieko Yamamoto , Ruano Rodrigo
Published: September 2020

Objective The present comprehensive review aims to show the full extent of what is known to date and provide a more thorough view on the effects of SARS-CoV2 in pregnancy.

Methods Between March 29 and May, 2020, the words COVID-19, SARS-CoV2, COVID-19 and pregnancy, SARS-CoV2 and pregnancy, and SARS and pregnancy were searched in the PubMed and Google Scholar databases; the guidelines from well-known societies and institutions (Royal College of Obstetricians and Gynaecologists [RCOG], American College of Obstetricians and Gynecologists [ACOG], International Society of Ultrasound in Obstetrics & Gynecology [ISUOG], Centers for Disease Control and Prevention [CDC], International Federation of Gynecology and Obstetrics [FIGO]) were also included.

Conclusion The COVID-19 outbreak resulted in a pandemic with > 3.3 million cases and 230 thousand deaths until May 2nd. It is caused by the SARS-CoV2 virus and may lead to severe pulmonary infection and multi-organ failure. Past experiences show that unique characteristics in pregnancy make pregnant women more susceptible to complications from viral infections. Yet, this has not been reported with this new virus. There are risk factors that seem to increase morbidity in pregnancy, such as obesity (body mass index [BMI] > 35), asthma and cardiovascular disease. Current reports describe an increased rate of preterm birth and C-section. Vertical transmission is still a possibility, due to a few reported cases of neonatal positive real-time polymerase chain reaction (RT-PCR) in nasal swab, amniotic fluid, and positive immunoglobulin M (IgM) in neonatal blood. Treatments must be weighed in with caution due to the lack of quality trials that prove their effectiveness and safety during pregnancy. Medical staff must use personal protective equipment in handling SARS-CoV2 suspected or positive patients and be alert for respiratory decompensations.
Size-derived reaction mechanism of core-shell aluminum nanoparticle
Authors: Chu Qingzhao , Shi Baolu , Liao Lijuan , Zhou Yintao , Luo Kai H. , Wang Ningfei
Published: September 2020

To prompt the application of aluminum nanoparticles (ANPs) in combustion as the fuel additive and in chemical synthesis as the catalyst, this study examines the reaction dynamics of core-shell ANPs under an oxygen atmosphere via Transient Non-Equilibrium Reactive Molecular Dynamics simulations. Two distinct oxidation modes determined by the competition between the oxide shell melting and core reaction have been identified. One is the fast oxidation mode with a high reaction heat release rate, where core Al and ambient O atoms diffuse into each other to form a homogeneous alumina particle. The other is the moderate oxidation with lower heat release, where only core Al atoms diffuse into the oxide shell to form a hollow spherical structure. By modeling the shell melting and Al core reaction, a size-derived oxidation model has been proposed to conveniently but accurately predict the ANP reaction dynamics. This work also provides fundamental insight into the synthesis of ANPs that serve as a high energy density fuel and high-performance catalyst.
Extraction of isotropic electron-nuclear hyperfine coupling constants of paramagnetic point defects from near-zero field magnetoresistance spectra via least squares fitting to models developed from the stochastic quantum Liouville equation
Authors: Frantz Elias B. , Harmon Nicholas J. , McMillan Stephen R. , Moxim Stephen J. , Flatté Michael E. , Lenahan Patrick M.
Published: September 2020

We report on a method by which we can systematically extract spectroscopic information such as isotropic electron–nuclear hyperfine coupling constants from near-zero field magnetoresistance (NZFMR) spectra. The method utilizes a least squares fitting of models developed from the stochastic quantum Liouville equation. We applied our fitting algorithm to two distinct material systems: Si/SiO2 metal oxide semiconductor field effect transistors and a-Si:H metal insulator semiconductor capacitors. Our fitted results and hyperfine parameters are in reasonable agreement with existing knowledge of the defects present in the systems. Our work indicates that the NZFMR response and fitting of the NZFMR spectrum via models developed from the stochastic quantum Liouville equation could be a relatively simple yet powerful addition to the family of spin-based techniques used to explore the chemical and structural nature of point defects in semiconductor devices and insulators.
Extraction of the local coordination and electronic structures of FeO6 octahedra using crystal field multiplet calculations combined with STEM-EELS
Authors: Haruta Mitsutaka , Nii Aoi , Hosaka Yoshiteru , Ichikawa Noriya , Saito Takashi , Shimakawa Yuichi , Kurata Hiroki
Published: September 2020

The material properties of metal oxides are sensitive to even low levels of cation doping, and the local atomic structures around such trace elements in a crystal will differ from the bulk structure due to the different ionic size and electron configuration. The present work explores the extraction of the local structure of a minority component contained in an atomic column by analyzing the Fe L2,3 energy-loss near-edge structure of atomic-resolution monochromated electron energy-loss spectra, using crystal field multiplet calculations. The crystal field splitting of the Fe 3d state and the local coordination structure of FeO6 octahedra in iron oxides in real space with known structures were determined. The results closely agreed with structures obtained from neutron diffraction and the Fe 3d DOS generated by density functional theory calculations. The previously unknown local structure of FeO6 octahedra present at octahedral sites as a minor component (14.4%) in the brownmillerite structure of Ca2Fe1.07Mn0.93O5 was determined. This structure was found to be unique and differed from the results obtained using neutron diffraction, which reflect those of mainly MnO6 octahedra. The present method is evidently an effective means of investigating the local structures around trace elements.
On the flip-flopping phenomenon of two side-by-side circular cylinders at a high subcritical Reynolds number of 1.4 × 105
Authors: Wu Gefei , Lin Weiqun , Du Xiaoqing , Shi Chunlin , Zhu Jiongyi
Published: September 2020

To investigate the flow characteristics of the biased gap flow and the flip-flopping phenomenon at high Reynolds numbers, large-eddy simulation is adopted to simulate the crossflow around two side-by-side circular cylinders at Re = 1.4 × 105. The center-to-center pitch ratio P/D varies from 1.1 to 4. Three flow patterns, i.e., single bluff body regime, biased gap flow regime, and coupled vortex regime, have been successfully simulated. A tri-stable flow pattern is found at P/D = 1.1; namely, a single bluff body regime and a biased gap flow regime deflected to the upper or lower cylinder occur spontaneously and intermittently. In contrast to the results obtained at low Reynolds numbers, two distinct biased gap flow structures are observed at P/D = 1.2 and 1.5, respectively. For P/D = 1.2, the gap-side shear layer separated from the narrow wake cylinder further reattaches to the cylinder; namely, a series of separation bubbles would develop along the gap-side surface of the cylinder. These unsteady separation bubbles induce the inward-directed lift force on the cylinder. For P/D = 1.5, the gap-side shear layer separates directly without further reattachment, and both cylinders experience outward lift forces. It is revealed that the flip-flopping of the biased gap flow is associated with the interaction of the gap vortices and the vortex shed from the outer-side shear layer of the wide wake cylinder. Furthermore, the flip-flopping phenomenon arises initially at one particular cross section of the cylinder, rather than occurring simultaneously along the spanwise direction of the cylinder.
Systematic differences in the relaxation stretching of polar molecular liquids probed by dielectric vs magnetic resonance and photon correlation spectroscopy
Authors: Körber Thomas , Stäglich Robert , Gainaru Catalin , Böhmer Roland , Rössler Ernst A.
Published: September 2020

Relaxation spectra of molecular glass formers devoid of secondary relaxation maxima, as measured by dielectric spectroscopy (DS), nuclear magnetic resonance (NMR) relaxometry, photon correlation spectroscopy (PCS), and Fabry–Perot interferometry, are quantitatively compared in terms of the Kohlrausch stretching parameter βK. For a reliable estimate of βK, the excess wing contribution has to be included in the spectral analysis. The relaxation stretching probed by PCS and NMR varies only weakly among the liquids (βK = 0.58 ± 0.06). It is similar to that found in DS, provided that the liquid is sufficiently nonpolar (relaxation strength Δε≲6). For larger strengths, larger βKDS (narrowed relaxation spectra) are found when compared to those reported from NMR and PCS. Frequency–temperature superposition (FTS) holds for PCS and NMR. This is demonstrated by data scaling and, for the few glass formers for which results are available, by the equivalence of the susceptibilities χPCS″ωτ∝χNMR″τ∝χNMR″ω, i.e., measuring at a constant frequency is equivalent to measuring at a constant temperature or constant correlation time. In this context, a plot of the spin–lattice relaxation rate R1(T) as a function of the spin–spin relaxation rate R2(T) is suggested to reveal the stretching parameter without the need to perform frequency-dependent investigations. Dielectrically, we identify a trend of increasing deviations from FTS with increasing Δε. Depending on the technique and glass former, the relative relaxation strength of the excess wing varies, whereas its exponent appears to be method independent for a given substance. For polar liquids, we discuss possible reasons for the discrepancy between the results from PCS and NMR as compared to those from DS.
Mid-infrared type-II InAs/InAsSb quantum wells integrated on silicon
Authors: Delli E. , Hodgson P. D. , Bentley M. , Repiso E. , Craig A. P. , Lu Q. , Beanland R. , Marshall A. R. J. , Krier A. , Carrington P. J.
Published: September 2020

Direct integration of III–V semiconductor light sources on silicon is an essential step toward the development of portable, on-chip infrared sensor systems. Driven by the presence of characteristic molecular fingerprints in the mid-infrared (MIR) spectral region, such systems may have a wide range of applications in infrared imaging, gas sensing, and medical diagnostics. This paper reports on the integration of an InAs virtual substrate and high crystalline quality InAs/InAsSb multi-quantum wells on Si using a three-stage InAs/GaSb/Si buffer layer. It is shown that the InAs/GaSb interface demonstrates a strong dislocation filtering effect. A series of strained AlSb/InAs dislocation filter superlattices was also used, resulting in a low surface dislocation density of approximately 4 × 107 cm−2. The InAs/InAsSb wells exhibited a strong photoluminescence signal at elevated temperatures. Analysis of these results indicates that radiative recombination is the dominant recombination mechanism, making this structure promising for fabricating MIR Si-based sensor systems.
Two-step light conversion with quantum dots inside non-linear crystals
Authors: Vorontsov Dmytro , Okrepka Galyna , Khalavka Yuriy , Valenta Jan
Published: September 2020

Up-conversion of infrared (IR) to visible light is demonstrated via an unconventional two-step process combining second harmonic generation with photoluminescence. This is achieved in a composite material formed by single crystals of KH2PO4 (KDP), in which CdTe/CdS quantum dots (QDs) are embedded during a crystal growth. The second harmonic generation from the IR laser frequency in KDP takes place, and then, generated light is absorbed by QDs and luminescence is emitted. Compared to the most common up-converting materials based on lanthanide ions, our novel composites use only abundant elements and have several other properties with application potential: the excitation and emission can cover a broader spectral range, and the response is much faster (ns compared to ms) and is strongly dependent on the direction of the incident beam.
Observation of surface dominated topological transport in strained semimetallic ErPdBi thin films
Authors: Bhardwaj Vishal , Bhattacharya Anupam , Nigam A. K. , Dash Saroj P. , Chatterjee Ratnamala
Published: September 2020

In this Letter, we present experimental observation of surface-dominated transport properties in [110]-oriented strained (∼1.6%) ErPdBi thin films. The resistivity data show typical semi-metallic behavior in the temperature range of 3 K ≤ T ≤ 350 K with a transition from semiconductor- to metal-like behavior below 3 K. The metallic behavior at low temperature disappears entirely in the presence of an external magnetic field >1 T. The weak-antilocalization (WAL) effect is observed in magneto-conductance data in the low magnetic field region and follows the Hikami–Larkin–Nagaoka (HLN) model. HLN fitting estimated single coherent channel, i.e., α ∼ −0.51 at 1.9 K, and the phase coherence length (Lϕ) shows the Lϕ ∼ T−0.52 power law dependence on temperature in the range of 1.9 K–10 K, indicating the observation of 2D WAL. Shubnikov–de Haas (SdH) oscillations are observed in magneto-resistance data below 10 K and are fitted to standard Lifhsitz Kosevich theory. Fitting reveals the effective mass of charge carriers ∼0.15 me and a finite Berry phase of 0.86π ± 0.16. The sheet carrier concentration and mobility of carriers estimated using SdH data are ns ∼ 1.35 × 1012 cm−2 and μs = 1210 cm2 V−1 s−1, respectively, and match well with the data measured using the Hall measurement at 1.9 K to be n ∼ 1.22 × 1012 cm−2, μ = 1035 cm2 V−1 s−1. These findings indicate the non-trivial nature and surface-dominated transport properties of strained (110) ErPdBi thin films at low temperatures.
In situ TEM study of crystallization and chemical changes in an oxidized uncapped Ge2Sb2Te5 film
Authors: Singh Manish Kumar , Ghosh Chanchal , Miller Benjamin , Kotula Paul G. , Tripathi Shalini , Watt John , Bakan Gokhan , Silva Helena , Carter C. Barry
Published: September 2020

Ge2Sb2Te5 (GST-225) has been the most used active material in nonvolatile phase-change memory devices. Understanding the kinetics and dynamics involved in crystallization is critical for the optimization of materials and devices. A GST-225 thin film of 20 nm thickness was prepared by sputtering directly onto a Protochip and left uncapped and exposed to atmosphere for approximately 1 year. Early stages of crystallization and growth of the film have been studied inside the TEM from room temperature to 140 °C. The morphological and structural transformations have been studied by a Cs-corrected environmental TEM, and images have been recorded using a high-speed low electron dose camera (Gatan K3 IS). The amorphous to crystalline transformation has been observed at ∼35 °C. From the large field, high-resolution images obtained using the Gatan K3 IS camera early crystallization can be detected and nucleation rates and growth velocities can be obtained.
The enigma of Oligocene climate and global surface temperature evolution
Authors: O’Brien Charlotte L. , Huber Matthew , Thomas Ellen , Pagani Mark , Super James R. , Elder Leanne E. , Hull Pincelli M.
Published: September 2020

Significance

During the Eocene, high-latitude regions were much warmer than today and substantial polar ice sheets were lacking. Indeed, the initiation of significant polar ice sheets near the end of the Eocene has been closely linked to global cooling. Here, we examine the relationship between global temperatures and continental-scale polar ice sheets following the establishment of ice sheets on Antarctica ∼34 million years ago, using records of surface temperatures from around the world. We find that high-latitude temperatures were almost as warm after the initiation of Antarctic glaciation as before, challenging our basic understanding of how climate works, and of the development of climate and ice volume through time.
Evolutionarily diverse LIM domain-containing proteins bind stressed actin filaments through a conserved mechanism
Authors: Winkelman Jonathan D. , Anderson Caitlin A. , Suarez Cristian , Kovar David R. , Gardel Margaret L.
Published: September 2020

Significance

Genes encoding LIM domains underwent a large expansion in animals. These LIM domain-containing proteins are functionally diverse and involved in a variety of fundamental cellular processes. Previous work suggests that many are sensitive to mechanical forces experienced by the cell. This study finds that many of these proteins in animals detect stressed cytoskeletal networks in cells by directly binding to a stretched conformation of the actin filament. This mechanism of force sensing by LIM within the cell is conserved from yeasts to mammals. This work suggests the possibility that a variety of biological pathways may be regulated by LIM domain detection of strained actin filaments.
High concentration of ultrafine particles in the Amazon free troposphere produced by organic new particle formation
Authors: Zhao Bin , Shrivastava Manish , Donahue Neil M. , Gordon Hamish , Schervish Meredith , Shilling John E. , Zaveri Rahul A. , Wang Jian , Andreae Meinrat O. , Zhao Chun , Gaudet Brian , Liu Ying , Fan Jiwen , Fast Jerome D.
Published: September 2020

Significance

The high-altitude tropics constitute one of the world’s largest aerosol reservoirs, which may significantly affect clouds, radiation, and hydrological cycle by delivering the seeds on which clouds form to lower altitudes and maintaining the stratospheric aerosol background. However, the formation mechanisms of these aerosols remain a scientific mystery. Through a systematic experiment-based model representation of organic chemistry and new particle formation (NPF) combined with constraints from field measurements, we demonstrate that the NPF driven by extremely low volatility organics formed from biogenic emissions plays a key role in producing the large number of aerosols observed in the high-altitude Amazon. This organic NPF mechanism likely also prevailed during preindustrial times and hence may modulate anthropogenic aerosol forcing above the preindustrial baseline.
Birds advancing lay dates with warming springs face greater risk of chick mortality
Authors: Shipley J. Ryan , Twining Cornelia W. , Taff Conor C. , Vitousek Maren N. , Flack Andrea , Winkler David W.
Published: September 2020

Significance

The advancement of breeding behavior is a well-documented response to changing climate conditions, as timing reproduction with resource availability is critical for success in many species. However, the relationship between cues that prompt reproduction and resource availability can become decoupled, reducing success. Tree swallows have advanced reproduction in response to warming springs, but now chicks are exposed to twice the risk of inclement weather conditions, resulting in high rates of chick mortality. Mass mortality events appear to be driven by decreasing insect availability at low daytime temperatures. Our findings highlight the complex effects of climate change on animal life cycles and demonstrate the urgency of understanding how animals balance information from the environment when making crucial life history decisions.
Superantigenic character of an insert unique to SARS-CoV-2 spike supported by skewed TCR repertoire in patients with hyperinflammation
Authors: Cheng Mary Hongying , Zhang She , Porritt Rebecca A. , Noval Rivas Magali , Paschold Lisa , Willscher Edith , Binder Mascha , Arditi Moshe , Bahar Ivet
Published: September 2020

Significance

A hyperinflammatory syndrome reminiscent of toxic shock syndrome (TSS) is observed in severe COVID-19 patients, including children with Multisystem Inflammatory Syndrome in Children (MIS-C). TSS is typically caused by pathogenic superantigens stimulating excessive activation of the adaptive immune system. We show that SARS-CoV-2 spike contains sequence and structure motifs highly similar to those of a bacterial superantigen and may directly bind T cell receptors. We further report a skewed T cell receptor repertoire in COVID-19 patients with severe hyperinflammation, in support of such a superantigenic effect. Notably, the superantigen-like motif is not present in other SARS family coronaviruses, which may explain the unique potential for SARS-CoV-2 to cause both MIS-C and the cytokine storm observed in adult COVID-19.
Near–hysteresis-free soft tactile electronic skins for wearables and reliable machine learning
Authors: Yao Haicheng , Yang Weidong , Cheng Wen , Tan Yu Jun , See Hian Hian , Li Si , Ali Hashina Parveen Anwar , Lim Brian Z. H. , Liu Zhuangjian , Tee Benjamin C. K.
Published: September 2020

Significance

We show a near–hysteresis-free piezoresistive sensor system from soft materials by using a method of generating unique three-dimensional nanoscale crack morphologies on metal-coated elastomeric microstructures. Our method addresses the major challenge of inherent electromechanical hysteresis faced by many electronic sensor skins using soft materials when large compressive pressures are applied. Piezoresistive sensors made from our flexible composite material track deformation with <3% hysteresis and can be reliably used as a healthcare wearable device for measuring pulse wave velocity on a small skin patch. We also showed that the low hysteresis enabled accurate and reliable single-touch classification of surface textures on textile surfaces for robotic applications.
ssRNA phage penetration triggers detachment of the F-pilus
Authors: Harb Laith , Chamakura Karthik , Khara Pratick , Christie Peter J. , Young Ry , Zeng Lanying
Published: September 2020

Significance

Many pathogenic bacteria utilize dynamic appendages called pili to facilitate important functions, such as gene transfer and motility. These processes contribute to the spread of antibiotic resistance genes and support persistence in bacterial infections, making them prime targets for therapeutic purposes. The single-stranded (ss) RNA bacteriophages all use dynamic pili to facilitate infection; however, key mechanistic details describing how the pilus promotes viral entry into the host cell have remained elusive. Here we used fluorescence microscopy to uncover a telling phenomenon associated with ssRNA phage infection: initial penetration of the viral payload causes breakage of host pili. This provides a selective advantage for the infecting phage, and thus this phenomenon may be widespread among other pilus-specific phage systems.
Experimental infection of domestic dogs and cats with SARS-CoV-2: Pathogenesis, transmission, and response to reexposure in cats
Authors: Bosco-Lauth Angela M. , Hartwig Airn E. , Porter Stephanie M. , Gordy Paul W. , Nehring Mary , Byas Alex D. , VandeWoude Sue , Ragan Izabela K. , Maison Rachel M. , Bowen Richard A.
Published: September 2020

Significance

SARS-CoV-2 is an emerging pathogen that has already had catastrophic consequences on the health and well-being of people worldwide. As a zoonotic virus, the implications for animal populations are largely unknown. This manuscript describes a pilot study in which domestic cats and dogs were assessed for their susceptibility to infection. While neither species developed clinical disease in this study, cats shed infectious virus for up to 5 d and infected naive cats via direct contact, while dogs do not appear to shed virus. Cats that were reinfected with SARS-CoV-2 mounted an effective immune response and did not become reinfected. These studies have important implications for animal health and suggest that cats may be a good model for vaccine development.
A systematic comparison of polar and semipolar Si-doped AlGaN alloys with high AlN content
Authors: Spasevski Lucia , Kusch Gunnar , Pampili Pietro , Zubialevich Vitaly Z , Dinh Duc V , Bruckbauer Jochen , Edwards Paul R , Parbrook Peter J , Martin Robert W
Published: September 2020

With a view to supporting the development of ultra-violet light-emitting diodes and related devices, the compositional, emission and morphology properties of Si-dopedn-type AlxGa1-xN alloys are extensively compared. This study has been designed to determine how the different AlxGa1-xN crystal orientations (polar (0001) and semipolar (11–22)) affect group-III composition and Si incorporation. Wavelength dispersive x-ray (WDX) spectroscopy was used to determine the AlN mole fraction (x≈ 0.57–0.85) and dopant concentration (3 × 1018–1 × 1019cm−3) in various series of AlxGa1-xN layers grown on (0001) and (11–22) AlN/sapphire templates by metalorganic chemical vapor deposition. The polar samples exhibit hexagonal surface features with Ga-rich boundaries confirmed by WDX mapping. Surface morphology was examined by atomic force microscopy for samples grown with different disilane flow rates and the semipolar samples were shown to have smoother surfaces than their polar counterparts, with an approximate 15% reduction in roughness. Optical characterization using cathodoluminescence (CL) spectroscopy allowed analysis of near-band edge emission in the range 4.0–5.4 eV as well as various deep impurity transition peaks in the range 2.7–4.8 eV. The combination of spatially-resolved characterization techniques, including CL and WDX, has provided detailed information on how the crystal growth direction affects the alloy and dopant concentrations.
The recurrence of dense face-centered cubic cesium
Authors: Guan Li-Min , Zhu Li , Xie Sheng-Yi
Published: September 2020

At ambient conditions, alkali metal cesium (Cs) owns a body-centered cubic phase, and this phase will transform to a face-centered cubic (fcc) phase at a pressure of 2.3 GPa. Under stronger compression, Cs will transform to oC84, tI4, oC16, and double hexagonal close-packed (dhcp) phases in sequence. Here, using first-principles structure searching prediction and total-energy calculation, we report that the Cs will re-transform to the fcc phase as the post-dhcp phase above 180 GPa. The transition state calculations suggest that the phase transition takes place by overcoming an energy barrier (144 meV/atom at 200 GPa) and finishes within a volume collapse of 0.3%. The electronic states at Fermi level are derived mainly from d electrons and there is a large overlap between inner core electrons, making the high-pressure fcc Cs distinguished from the first one at low pressure. The same phase transition also occurs in potassium and rubidium but with higher pressures.
Switchable cool and cold white emission from dysprosium doped SrZnO2
Authors: Manju  , Jain Megha , Vashishtha Pargam , Gupta Govind , Sharma Aditya , Ok Won Sung , Vij Ankush , Thakur Anup
Published: September 2020

In presented work, excitation selective novel cool and cold white emission is reported from dysprosium (Dy) doped SrZnO2 nanophosphors, synthesized by combustion technique. The host lattice provided selective excitation routes for Dy3+ levels and intrinsic defects levels via charge transfer (270 nm) and host defects absorption bands (375 nm), respectively. The emission due to Dy3+ levels was found to be exhibiting cool white emission and that from intrinsic defects was cold white emission, as characterized from correlated color temperature. UV irradiated glow curve analysis complemented the results by exhibiting signal due to Dy assisted traps on near UV exposure (254 nm) and that of host related traps at far UV exposure (365 nm). The luminescence phenomenon is comprehended through proposed band model. The obtained results proclaimed SrZnO2:Dy as a potential member among white emitting phosphors to be used as standard daylight sources in commercial and aesthetic lighting.
Development of a biaxial grid-coil-type electromagnetic acoustic transducer
Authors: Yang Li-Jian , Zhang Jia , Xing Yan-Hao , Gao Song-Wei , Xie Zhe , Fu Hong-Wen
Published: September 2020

This study proposes a grid-coil-type transducer to achieve the simultaneous detection of axial and circumferential cracks in the pipeline, reduce the number of permanent magnets in dynamic detection, and improve crack detection efficiency. The proposed system can detect biaxial cracks in the pipeline. Based on Biot–Savart’s Law, a mathematical model is established between the magnetic induction intensity and the coil of the electromagnetic acoustic transducer to determine the influence on the conductor. Experiments verify the relationship between the guided wave propagation characteristics of the grid-coil-type electromagnetic acoustic transducer and the ability to detect biaxial cracks. Results show that the grid-coil-type electromagnetic acoustic transducer can generate the biaxial ultrasonic guided wave propagating along the axial and circumferential pipeline, in which cracks are thereby simultaneously detected. Thus, the grid-coil-type electromagnetic acoustic transducer increases the detection scope, reduces the number of permanent magnets in dynamic detection, and improves crack detection efficiency. This study provides a theoretical and experimental basis for the research and engineering application of biaxial crack detection in the pipeline.
Optical rotation detection method based on acousto-optic modulation in an atomic spin co-magnetometer
Authors: Xing Li , Zhai Yueyang , Fu Yang , Song Tianxiao , Liu Feng , Cai Qingzhong , Quan Wei
Published: September 2020

A new concept for probe light intensity stability control and high-frequency modulation based on an acousto-optic modulation in a K-Rb-21Ne co-magnetometer is reported. The structure and optical path are ingeniously designed to avoid the interference of zero-order diffraction light. The average rotation rate sensitivity of

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is achieved under the light intensity closed-loop control condition and the bias instability calculated by the Allan deviation is improved from 0.13 deg h−1 to 0.06 deg h−1 comparing with open-loop scheme. A square wave modulation with a wide range of frequencies is applied to the probe light intensity and the appropriate modulation frequency for the co-magnetometer is tested to be 10 kHz to 300 kHz and megahertz scale. Finally, the closed-loop control of light intensity has been combined with the high-frequency modulation, which could suppress the low-frequency noise contained in the probe system and improve the long-term stability of the angular velocity measurement.
Locking effects of error fields on a tearing mode in tokamak
Authors: Lu S S , Ma Z W , Zhang H W , Liu Y
Published: September 2020

Locking effects of error fields on a tearing mode in Tokamak are studied numerically using the three-dimensional toroidal code based on a full set of magnetohydrodynamic equations. It is found that a threshold of the error field for mode locking exists and depends on the plasma rotation and the ramp-up time of the error field. The mode locking threshold increases with increasing the rotation frequency and the ramp-up time of the error field. Moreover, the results from the multiple helical error field suggest that the m/n = 3/1 and 4/2 error field along with the m/n = 2/1 error field can increase both the m/n = 2/1 perturbation and its higher-harmonics through the mode coupling due to both the toroidal and nonlinear effects, but it becomes more effective if the 4/2 error field is imposed directly. The 3/1 error field in-phase (anti-phase) with the 2/1 error field leads to a positive (negative) contribution to intensification of the 2/1 tearing mode and mode locking.
Propagation and ramification of a solitary pulse through an environmentally coupled qubit
Authors: Gao Yibo , Jin Shijie , Ian Hou
Published: September 2020

We compute the relaxations experienced by a superconducting qubit and the simultaneous variation induced on the shape of a microwave pulse during the propagation of the pulse through the qubit. The environmentally affected propagation and the dressed relaxations are accounted by a microscopic-master-Maxwell equation pair. It is shown that the qubit longitudinal relaxation vanishes when the pulse envelope adopts a solitonic shape of nπ area whereas its transverse relaxation vanishes when the pulse phase has a periodic variation that is orthogonal to the spectral density of the environment. The pulse would propagate absorption-free when its area matches 2nπ. Otherwise, the environmental feedback decelerates the velocity of the soliton envelope and induces an monotonic increase of phase in the microwave. A pulse of non-2nπ area thus ramifies into a transparent part that travels absorption-free at incident velocity and a slowing part that decays through space. The ramification explains the environmental origin of pulse splitting observed in self-induced transparency.
Modulation instability and rogue wave spectrum for the generalized nonlinear Schrödinger equation
Authors: Zhou Jiale , Tang Yaning , Zhang Linpeng
Published: September 2020

We discuss modulation instability for the generalized nonlinear Schrödinger equation based on nonzero background wave frequency. First of all, we analyze the existence condition of modulation instability under different perturbed frequency. The influences of the background amplitude, background frequency and perturbed frequency on the modulation instability gain are researched, respectively. Also, we obtain the correspondences between several nonlinear excitations (Kuznetsov-Ma breather, general breather, rogue wave, bright soliton and plane wave) and modulation instability according to new parameters. Furthermore, by the Fourier transformation method, we perform spectrum analyses of the first-order and second-order rogue waves. The perturbed frequency of the rogue wave can affect the location and profile of the spectrum. And we find that the spectrum of the second-order rogue wave is jagged due to the collision of the rogue waves. These results would help us further understand the dynamics of rogue wave in complex systems.
Recoil and assembling clearance on roller dynamic analysis for cylinder cam mechanism
Authors: Xu Jian , Song Lanwei , Yang Zhen , Li Qiang
Published: September 2020

In order to give the clearance and assembling recoil to the fixed cylinder cam mechanism, the main roller was dynamic analyzed. The system dynamics was done and the force changes quickly on the main roller and the force has a great value. Assembling clearance between the main roller and the cam curve slot, the main roller can suddenly rotate and it can reverse in several short intervals in theoretical analysis and test experiments, so that the huge friction force in the extremely short time will be the main wear factor. So that the main roller does not necessarily rotate in its validity period, and we are a kind of alarm of rolling or not.