bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature constraints from inversions of synthetic solar optical, UV, and radio spectra
Authors: da Silva Santos J. M. , de la Cruz Rodríguez J. , Leenaarts J.
Published: September 2018

Context. High-resolution observations of the solar chromosphere at millimeter wavelengths are now possible with the Atacama Large Millimeter Array (ALMA), bringing with them the promise of tackling many open problems in solar physics. Observations from other ground and space-based telescopes will greatly benefit from coordinated endeavors with ALMA, yet the diagnostic potential of combined optical, ultraviolet and mm observations has remained mostly unassessed.

Aims. In this paper we investigate whether mm-wavelengths could aid current inversion schemes to retrieve a more accurate representation of the temperature structure of the solar atmosphere.

Methods. We performed several non-LTE inversion experiments of the emergent spectra from a snapshot of 3D radiation-MHD simulation. We included common line diagnostics such as Ca II H, K, 8542 Å and Mg II h and k, taking into account partial frequency redistribution effects, along with the continuum around 1.2 mm and 3 mm.

Results. We find that including the mm-continuum in inversions allows a more accurate inference of temperature as function of optical depth. The addition of ALMA bands to other diagnostics should improve the accuracy of the inferred chromospheric temperatures between log τ ∼ [−6, −4.5] where the Ca II and Mg II lines are weakly coupled to the local conditions. However, we find that simultaneous multiatom, non-LTE inversions of optical and UV lines present equally strong constraints in the lower chromosphere and thus are not greatly improved by the 1.2 mm band. Nonetheless, the 3 mm band is still needed to better constrain the mid-upper chromosphere.
Grid of upper atmosphere models for 1–40 M⊕ planets: application to CoRoT-7 b and HD 219134 b,c
Authors: Kubyshkina D. , Fossati L. , Erkaev N. V. , Johnstone C. P. , Cubillos P. E. , Kislyakova K. G. , Lammer H. , Lendl M. , Odert P.
Published: September 2018

There is growing observational and theoretical evidence suggesting that atmospheric escape is a key driver of planetary evolution. Commonly, planetary evolution models employ simple analytic formulae (e.g. energy limited escape) that are often inaccurate, and more detailed physical models of atmospheric loss usually only give snapshots of an atmosphere’s structure and are difficult to use for evolutionary studies. To overcome this problem, we have upgraded and employed an existing upper atmosphere hydrodynamic code to produce a large grid of about 7000 models covering planets with masses 1–39 M⊕ with hydrogen-dominated atmospheres and orbiting late-type stars. The modelled planets have equilibrium temperatures ranging between 300 and 2000 K. For each considered stellar mass, we account for three different values of the high-energy stellar flux (i.e. low, moderate, and high activity). For each computed model, we derived the atmospheric temperature, number density, bulk velocity, X-ray and EUV (XUV) volume heating rates, and abundance of the considered species as a function of distance from the planetary centre. From these quantities, we estimate the positions of the maximum dissociation and ionisation, the mass-loss rate, and the effective radius of the XUV absorption. We show that our results are in good agreement with previously published studies employing similar codes. We further present an interpolation routine capable to extract the modelling output parameters for any planet lying within the grid boundaries. We used the grid to identify the connection between the system parameters and the resulting atmospheric properties. We finally applied the grid and the interpolation routine to estimate atmospheric evolutionary tracks for the close-in, high-density planets CoRoT-7 b and HD 219134 b,c. Assuming that the planets ever accreted primary, hydrogen-dominated atmospheres, we find that the three planets must have lost them within a few Myr.
Transient Isolated Polyhydramnios and Perinatal Outcomes
Authors: Berezowsky Alexandra , Ashwal Eran , Hiersch Liran , Yogev Yariv , Aviram Amir
Published: September 2018

Purpose To evaluate labor and perinatal outcomes of transient isolated polyhydramnios.

Materials and Methods A retrospective cohort study (2008–2013) at a university-affiliated, tertiary medical center. Eligibility was limited to patients with singleton gestations, no maternal diabetes or known structural/chromosomal anomalies, and no rupture of the membranes prior to delivery, at > 34 weeks of gestation. All women underwent routine sonogram for estimation of fetal weight (sEFW) between 28–34 weeks of gestation, and a second routine sonogram at admission. We compared women diagnosed with polyhydramnios at the time of the sEFW which later resolved, with women who had normal AFI during the sEFW.

Results Overall, 44 263 women delivered during this time period, of which 292 (0.7 %) with transient polyhydramnios (study group) and 29 682 with a normal amniotic fluid level (control group) were eligible for analysis. Women with transient polyhydramnios had a higher risk for assisted vaginal delivery (AVD), mainly due to abnormal/intermediate fetal heart rate tracings (aOR 2.3, 95 % CI 1.2–5.5), and a higher risk for cesarean delivery (CD), mostly because of labor dystocia (aOR 2.5, 95 % CI 1.2–5.1 for 1st stage arrest and aOR 3.4, 95 % CI 1.6–7.2) for 2nd stage arrest), suspected macrosomia (aOR 3.2, 95 % CI 1.6–6.6) and malpresentation (aOR 6.6, 95 % CI 2.0–21.1).

Conclusion Transient isolated polyhydramnios detected during the sonogram at 28–32 weeks of gestation is an independent risk factor for the need for obstetrical intervention during labor.
Standardisierte Nachbesprechung von Zwangsmaßnahmen auf psychiatrischen Akutstationen: Ergebnisse einer Pilotstudie
Authors: Wullschleger Alexandre , Vandamme Angelika , Ried Jennifer , Pluta Mara , Montag Christiane , Mahler Lieselotte
Published: September 2018

Ziel Pilotstudie zur Untersuchung eines Leitfadens zur standardisierten Nachbesprechung erfolgter Zwangsmaßnahmen.

Methodik Nach Durchführung von 12 Nachbesprechungen wurden teilnehmende Patienten und Mitarbeiter mittels eines selbstentwickelten Fragebogens mit quantitativen und qualitativen Fragen sowie qualitativer Experten-Interviews befragt.

Ergebnisse Die Intervention wurde von allen Befragten als hilfreich erlebt, insbesondere um die therapeutische Beziehung zu fördern. Der Zeitpunkt des Gesprächs sollte individuell gewählt werden.

Schlussfolgerung Der Leitfaden eignet sich zur Nachbesprechung von Zwangsmaßnahmen.
Predictive Factors for Vitamin D Concentrations in Swiss Athletes: A Cross-sectional Study
Authors: Zürcher Simeon , Quadri Andrea , Huber Andreas , Thomas Lothar , Close Graeme , Brunner Saskia , Noack Patrik , Gojanovic Boris , Kriemler Susi
Published: September 2018

Vitamin D concentrations corresponding to 75 nmol/L 25(OH)D have been associated with maintained muscle function, growth and regeneration, optimal bone health and immunology in athletes. The objective of this study was to investigate the prevalence and predictors of insufficient 25(OH)D concentrations in athletes. Six hundred three Swiss athletes were assessed. 25(OH)D was analysed by high-performance liquid chromatography (HPLC). A standardized questionnaire was used to gather information about potential predictors for 25(OH)D concentrations; 50.5% showed insufficient 25(OH)D concentrations. Differences in predicted probability of insufficient 25(OH)D were found for those vitamin D supplemented (42%) versus not supplemented (52%), in those performing indoor (58%) versus outdoor sports (43%), and during the sun-deprived seasons of fall (49%), winter (70%) and spring (57%) compared with summer (17%). Higher BMI z-scores and age were associated with higher 25(OH)D concentrations. In conclusion, insufficient 25(OH)D concentrations were common among athletes especially at a younger age, among those not supplemented, in athletes who trained indoors, and during the sun-deprived seasons. Because the prevalence of insufficient 25(OH)D concentrations in this study was high, regular supplementation in athletes may be indicated, except perhaps during the summer season. Further research is needed to determine which 25(OH)D concentrations lead to optimal health and performance in athletes.
Diet and Lifestyle Before and During Pregnancy – Practical Recommendations of the Germany-wide Healthy Start – Young Family Network
Authors: Koletzko Berthold , Cremer Monika , Flothkötter Maria , Graf Christine , Hauner Hans , Hellmers Claudia , Kersting Mathilde , Krawinkel Michael , Przyrembel Hildegard , Röbl-Mathieu Marianne , Schiffner Ulrich , Vetter Klaus , Weißenborn Anke , Wöckel Achim
Published: September 2018

Diet and exercise before and during pregnancy affect the course of the pregnancy, the childʼs development and the short- and long-term health of mother and child. The Healthy Start – Young Family Network has updated the recommendations on nutrition in pregnancy that first appeared in 2012 and supplemented them with recommendations on a preconception lifestyle. The recommendations address body weight before conception, weight gain in pregnancy, energy and nutritional requirements and diet (including a vegetarian/vegan diet), the supplements folic acid/folate, iodine, iron and docosahexaenoic acid (DHA), protection against food-borne illnesses, physical activity before and during pregnancy, alcohol, smoking, caffeinated drinks, oral and dental hygiene and the use of medicinal products. Preparation for breast-feeding is recommended already during pregnancy. Vaccination recommendations for women planning a pregnancy are also included. These practical recommendations of the Germany-wide Healthy Start – Young Family Network are intended to assist all professional groups that counsel women and couples wishing to have children and during pregnancy with uniform, scientifically-based and practical information.
Trigeminal Nerve Schwannoma of the Cerebellopontine Angle
Authors: Peris-Celda Maria , Graffeo Christopher , Perry Avital , Carlstrom Lucas , Link Michael
Published: September 2018

Introduction Large and even moderate sized, extra-axial cerebellopontine angle (CPA) tumors may fill this restricted space and distort the regional anatomy. It may be difficult to determine even with high resolution magnetic resonance imaging (MRI) if the tumor is dural-based, or what the nerve of origin is if a schwannoma. While clinical history and exam are helpful, they are not unequivocal, particularly since many patients present with a myriad of symptoms, or conversely an incidental finding. We present an atypical appearing, asymptomatic CPA tumor, ultimately identified at surgery to be a trigeminal schwannoma.

Case History A 40-year-old man presented with new-onset seizure. MRI identified an incidental heterogeneously contrast-enhancing CPA lesion (Fig. 1A–D). The tumor was centered on the internal auditory canal (IAC) with no tumor extension into Meckel's cave, IAC or jugular foramen. Audiometry demonstrated 10db of relative left-sided hearing loss with 100% word recognition. Physical examination was negative for focal neurologic deficits. A retrosigmoid craniotomy was performed and an extra-axial, yellow-hued mass was encountered and resected, which was ultimately confirmed to originate from the trigeminal nerve (Video 1). Gross total resection was achieved, and the patient recovered from surgery with partial ipsilateral trigeminal sensory loss and no other new neurologic deficits.

Conclusion Pure CPA trigeminal schwannomas are rare, but should be considered in the differential for enhancing CPA lesions. Although, Meckel's cave involvement is frequently observed, it is not universal, and pure CPA schwannomas of all cranial nerves IV–XII have been reported in the literature.

The link to the video can be found at: https://youtu.be/AlodYCu70F8.
Gross Total Resection of Large Cerebellopontine Angle Meningioma with a Supratentorial Extension via Retrosigmoid Approach with Suprameatal Drilling and Tentorial Sectioning
Authors: Sayyahmelli Sima , Ahmetspahic Adi , Baskaya Mustafa
Published: September 2018

Meningiomas are the second most common neoplasm in the cerebellopontine angle (CPA), and are challenging lesions to treat surgically. With significant refinements in surgical techniques, operative morbidity, and mortality have been substantially reduced. Total or near-total surgical resection can be accomplished in the majority of cases via appropriately selected approaches, and with acceptable morbidity. In this video, we present a 51-year-old woman, who had a 2-year history of vertigo with symptoms that progressed over time. She presented with blurry vision, sensorineural hearing loss, tinnitus, left-sided facial numbness, and double vision. Magnetic resonance imaging (MRI) showed a left-sided homogeneously enhancing mass at CPA with a supratentorial extension. MRI appearance was consistent with a CPA meningioma with supratentorial extension. The patient underwent surgical resection via a retrosigmoid approach. Suprameatal drilling and tentorial sectioning were necessary to achieve gross total resection. The surgery and postoperative course were uneventful. The histopathology was a WHO (world health organization) grade I meningioma. MRI showed gross total resection of the tumor. After a 1.5-year follow-up, the patient is continuing to do well with no residual or recurrent disease. In this video, microsurgical techniques and important steps for the resection of this challenging meningioma of the cerebellopontine angle are demonstrated.

The link to the video can be found at: https://youtu.be/CDto52GxrG4.
Retrosigmoid Approach for Resection of Cerebellar Peduncle Cavernoma
Authors: Abou-Al-Shaar Hussam , Alzhrani Gmaan , Gozal Yair , Couldwell William
Published: September 2018

The case described in this video involved a 38-year-old man, who presented with a 4-week history of worsening acute-onset headache, nausea, double vision, and vertigo. On examination, he had impaired tandem gait and diplopia on right horizontal gaze. A computed tomography (CT) scan revealed a hyperdense lesion of the right cerebellopontine angle. Magnetic resonance imaging (MRI) revealed a nonenhancing middle cerebellar peduncle lesion that was isointense on T2-weighed imaging and hypointense on FLAIR imaging (Fig. 1A–B). The differential diagnoses for this lesion included cavernous malformation, thrombosed aneurysm, and neurocysticercosis. CT angiography was done preoperatively to rule out cerebral aneurysm. Surgical resection of the lesion was recommended to relieve his symptoms, to prevent further deterioration/bleeding, and to obtain a pathological diagnosis. The patient underwent a right retrosigmoid craniotomy for resection of the right middle cerebellar peduncle cavernoma (Fig. 2). The patient tolerated the procedure well with no new postoperative neurological deficit. Postoperative MRI depicted gross total resection of the lesion and expected residual blood in the resection cavity (Fig. 1C–D). The patient was discharged home on postoperative day 4. At his last follow-up appointment, 1 month after surgery, he reported complete resolution of his preoperative symptoms, including diplopia. The patient gave consent for publication.

The link to the video can be found at: https://youtu.be/TRieS9DXbV4.
Extreme Lateral Supracerebellar Infratentorial Approach to the Lateral Midbrain
Authors: Kalani M. , Couldwell William
Published: September 2018

This video illustrates the case of a 52-year-old man with a history of multiple bleeds from a lateral midbrain cerebral cavernous malformation, who presented with sudden-onset headache, gait instability, and left-sided motor and sensory disturbances. This lesion was eccentric to the right side and was located in the dorsolateral brainstem. Therefore, the lesion was approached via a right-sided extreme lateral supracerebellar infratentorial (exSCIT) craniotomy with monitoring of the cranial nerves. This video demonstrates the utility of the exSCIT for resection of dorsolateral brainstem lesions and how this approach gives the surgeon ready access to the supracerebellar space, and cerebellopontine angle cistern. The lateral mesencephalic safe entry zone can be accessed from this approach; it is identified by the intersection of branches of the superior cerebellar artery and the fourth cranial nerve with the vein of the lateral mesencephalic sulcus. The technique of piecemeal resection of the lesion from the brainstem is presented. Careful patient selection and respect for normal anatomy are of paramount importance in obtaining excellent outcomes in operations within or adjacent to the brainstem.

The link to the video can be found at: https://youtu.be/aIw-O2Ryleg.
“Augmentative and Alternative Communication (AAC) Will Give You a Voice”: Key Practices in AAC Assessment and Intervention as Described by Persons with Amyotrophic Lateral Sclerosis
Authors: Giambalvo Felicia , Kohler Kim , Nazareth Godfrey , Caron Jessica , Fager Susan , McNaughton David
Published: September 2018

The purpose of this study was to describe the perceptions of persons with amyotrophic lateral sclerosis (pALS) who use augmentative and alternative communication (AAC) with the AAC assessment and intervention process. Twenty-one pALS with complex communication needs participated in a multipart survey (and follow-up e-mails) to provide information on their experiences with AAC assessment and intervention. A majority of the participants agreed with the importance of three key AAC intervention principles: appropriate staging of the timing of assessment and intervention activities, inclusion of communication partners, and the use of multiple modalities and strategies as communication supports. Most participants reported that their assessment and intervention experiences included at least some aspect of these three key practices. The results of this study suggest that the identified best practices in AAC should be reviewed and implemented on an individualized basis for pALS with complex communication needs.
Fetal Abdominal Aorta: Doppler and Structural Evaluation of Endothelial Function in Intrauterine Growth Restriction and Controls
Authors: Visentin Silvia , Londero Ambrogio , Calanducci Maria , Grisan Enrico , Bongiorno Maria , Marin Loris , Cosmi Erich
Published: September 2018

Purpose The human aorta stores strain energy in the distended wall during systole through the extracellular matrix of the tunica media that could be influenced by blood pressure, flow, or increased peripheral resistance. In intrauterine growth restriction (IUGR) fetuses, the increased aorta intima media thickness (aIMT) could reflect a different extracellular matrix composition and, therefore, functionality. The aim of this study was to analyze the resistance to flow in the fetal descending aorta and its relation to aIMT and systolic and diastolic fetal abdominal aorta diameters in IUGR fetuses and controls.

Materials and Methods This is a prospective case control study of single pregnancies collected at a tertiary center for feto-maternal medicine in Northeast Italy. An IUGR group as cases and a group of fetuses appropriate for gestational age (AGA) as controls were included.

Results We found a greater PI of the fetal abdominal aorta in the IUGR group (1.82) than in the AGA group (1.21) (p < 0.05). The change between the systolic and diastolic fetal abdominal aorta diameters was significantly greater in IUGR fetuses (0.10 mm (IQR 0.07 – 0.28)) than in the AGA group (0.04 mm (0.03 – 0.05)) (p < 0.05). In the IUGR group aIMT was significantly correlated with peak systolic velocity (PSV) and systolic-diastolic aorta diameter change, while these two correlations were not found in the control group.

Conclusion The change between the systolic and diastolic fetal abdominal aorta diameters in IUGR cases during the early third trimester of pregnancy was significantly increased and aIMT in the IUGR group was significantly correlated to systolic-diastolic diameter change and PSV, probably reflecting aortic wall adaptation to blood flow changes in IUGR fetuses.
Adaptation of a visible wavelength fluorescence microplate reader for discovery of near-infrared fluorescent probes
Authors: Swasey Steven M. , Nicholson Hunter C. , Copp Stacy M. , Bogdanov Petko , Gorovits Alexander , Gwinn Elisabeth G.
Published: September 2018

We present an inexpensive, generalizable approach for modifying visible wavelength fluorescence microplate readers to detect emission in the near-infrared (NIR) I (650–950 nm) and NIR II (1000-1350 nm) tissue imaging windows. These wavelength ranges are promising for high sensitivity fluorescence-based cell assays and biological imaging, but the inaccessibility of NIR microplate readers is limiting development of the requisite, biocompatible fluorescent probes. Our modifications enable rapid screening of NIR candidate probes, using short pulses of UV light to provide excitation of diverse systems including dye molecules, semiconductor quantum dots, and metal clusters. To confirm the utility of our approach for rapid discovery of new NIR probes, we examine the silver cluster synthesis products formed on 375 candidate DNA strands that were originally designed to produce green-emitting, DNA-stabilized silver clusters. The fast, sensitive system developed here discovered DNA strands that unexpectedly stabilize NIR-emitting silver clusters.
Hafnium oxide and tantalum oxide based resistive switching structures for realization of minimum and maximum functions
Authors: Fröhlich Karol , Kundrata Ivan , Blaho Michal , Precner Marian , Ťapajna Milan , Klimo Martin , Šuch Ondrej , Škvarek Ondrej
Published: September 2018

While the main application of resistive switching structures currently targets non-volatile memories, increasing interest is being focused on their logic applications. Resistive switches are suitable for Boolean logic, neuromorphic computing and for implementation of Zadeh fuzzy logic. In this work, we analyzed implementation of the resistive switching structures for logic application based on Zadeh fuzzy logic. Resistive switching structures based on hafnium oxide and tantalum oxide were connected in an anti-serial configuration (complementary resistive switch). The complementary resistive switches integrated into logic circuit for Min-Max function implementation were analyzed using quasi-static voltage sweeps. We have shown that the accuracy of the Min/Max function determination depends on the ratio of the high and low resistivity states of the single switches. Determination of the Min/Max values is relevant only above the threshold voltage of the resistive structures. Reproducibility of the Min/Max function constructed from the resistive switching structures was evaluated. In addition, pulsed reconfiguration of complementary resistive switch using 100 ns long pulses was demonstrated.
A high temperature gas flow environment for neutron total scattering studies of complex materials
Authors: Olds Daniel , Mills Rebecca A. , McDonnell Marshall T. , Liu Jue , Kim Joshua R. , Dunstan Matthew T. , Gaultois Michael W. , Everett S. Michelle , Tucker Matthew G. , Page Katharine
Published: September 2018

We present the design and capabilities of a high temperature gas flow environment for neutron diffraction and pair distribution function studies available at the Nanoscale Ordered Materials Diffractometer instrument at the Spallation Neutron Source. Design considerations for successful total scattering studies are discussed, and guidance for planning experiments, preparing samples, and correcting and reducing data is defined. The new capabilities are demonstrated with an in situ decomposition study of a battery electrode material under inert gas flow and an in operando carbonation/decarbonation experiment under reactive gas flow. This capability will aid in identifying and quantifying the atomistic configurations of chemically reactive species and their influence on underlying crystal structures. Furthermore, studies of reaction kinetics and growth pathways in a wide variety of functional materials can be performed across a range of length scales spanning the atomic to the nanoscale.
On the conductivity in a two-dimensional molecular π-stack with application to charge transport in DNA solid-state devices
Authors: Kopylova Tatjana N. , Nikonov Sergey Yu. , Telminov Evgeny N. , Gadirov Ruslan M. , Degtyarenko Konstantin M. , Burtman Vladimir
Published: September 2018

Charge transport in a naphthalene π-stack system can exhibit switching because of variation in its redox state. We study this phenomenon in a molecular π-stack with the aim of obtaining insight into the charge transport in DNA solid-state devices. The model molecular π-stack is based on the structure of naphthalene tetracarboxylic diimide (NTCDI), which is assembled by molecular layer epitaxy (MLE). MLE enables controllable growth of two-dimensional organic frameworks featuring ordered π-stacked arrays of aromatic molecules. These molecular stacks are grown in the in-plane direction with respect to the surface and are bonded covalently to the inorganic semiconducting substrate. In this system, the reduced NTCDI acceptors form redox polarons in which the charge is shared over several molecules within the π-stack. We study the experimental conditions that are required to sustain efficient transport in this redox-capable NTCDI molecular π-stack. The transport in this redox-active system follows the behavior of the polarons. Polaron transport occurs below the HOMO–LUMO gap in a molecular system, for which either ln I ∼ −E−2/3 or I ∼ E (linear regime). We also study the case of redox blockade for the NTCDI molecular π-stack. We demonstrate that the same model (i.e., ln I ∼ −E−2/3) is applicable for transport through DNA molecules positioned between nano-electrodes. Studying the transport in a molecular π-stack enables elucidation of the phenomenon of conductivity switching, which may be responsible for the discrepancies among different transport experiments with DNA solid-state devices. We propose a generalized-effective-medium approach to describe the redox polaron transport in a molecular stack, an approach that is based on a fully compensated semiconductor model.
Effect of oxygen as additive on an atmospheric nanosecond pulsed helium plasma jet impinging on a dielectric surface
Authors: Zheng Yashuang , Wang Lijun , Wang Dan
Published: September 2018

Based on a 2D axisymmetric plasma fluid model, the effect of the levels of O2 admixtures on the plasma dynamics of an atmospheric pressure He plasma jet incident on a dielectric surface situated normal to the jet axis has been studied. The introduction of O2 admixture in the feedstock gas changes the shape of the discharge ionization rate that approaches the target surface from a ring to a solid disk. As the streamer extinguishes radial propagation along the dielectric surface, comparatively larger plasma-surface contact areas were obtained for O2 additions to the He plasma of less than 0.5% relative to that for the discharge in pure He, while in the case of 2% O2, the radial propagation distance dropped off significantly. The propagation of an ionization wave peaked in the range 0.2%–1% for the O2 admixture. The enhanced ionization reactions are considered to predominate for small concentrations of O2 as additive, and the negative role played by the excitation energy loss and the attachment of electrons to O2 is more important with the addition of 2% O2. There was a remarkable incremental gain in the flux intensity of O on the surface center, while the flux of N was mainly concentrated on the streamer head. The magnitude of the O flux on the surface showed a peak at the 0.5% O2 admixture level, and the flux of O3 on the surface was directly proportional to the O2 concentration.
Thermoelectric radiation detector based on a superconductor-ferromagnet junction: Calorimetric regime
Authors: Chakraborty Subrata , Heikkilä Tero T.
Published: September 2018

We study the use of a thermoelectric junction as a thermal radiation detector in the calorimetric regime, where single radiation bursts can be separated in time domain. We focus especially on the case of a large thermoelectric figure of merit ZT affecting significantly, for example, the relevant thermal time scales. This work is motivated by the use of hybrid superconductor/ferromagnet systems in creating an unprecedentedly high low-temperature ZT even exceeding unity. Besides constructing a very general noise model which takes into account cross correlations between charge and heat noise, we show how the detector signal can be efficiently multiplexed by the use of resonant LC circuits giving a fingerprint to each pixel. We show that for realistic detectors operating at temperatures around 100 to 200 mK, the energy resolution can be as low as 1 meV. This allows for a broadband single-photon resolution at photon frequencies of the order of or below 1 THz.
Current capabilities of the residual stress diffractometer at the high flux isotope reactor
Authors: Cornwell P. , Bunn J. , Fancher C. M. , Payzant E. A. , Hubbard C. R.
Published: September 2018

The engineering diffractometer 2nd Generation Neutron Residual Stress Facility (NRSF2) at the Oak Ridge National Laboratory’s High Flux Isotope Reactor was built specifically for the mapping of residual strains. NRSF2 is optimized to investigate a wide range of engineering materials by providing the user a selection of monochromatic neutron wavelengths to maintain the selected Bragg reflection near 2θ = 90°, which is the optimal scattering geometry for strain mapping. Details of the instrument configuration and operation are presented, and considerations for experimental planning are also discussed. Selected examples of recent residual stress work completed with NRSF2 are presented to highlight capabilities.
Theoretical basis of SQUID-based artificial neurons
Authors: Katayama Haruna , Fujii Toshiyuki , Hatakenaka Noriyuki
Published: September 2018

The physical basis of an artificial neuron is studied using a model that is based on the stochastic transition between two states in a double well potential. It is shown that the stochastic transition model generates an energy-defined sigmoid function acting as an activation (or transfer) function in neurons. The model is also applied to circuit neurons using superconducting quantum interference devices in artificial neural networks.
Bipolar to unipolar mode transition and imitation of metaplasticity in oxide based memristors with enhanced ionic conductivity
Authors: Cheng Caidie , Li Yiqing , Zhang Teng , Fang Yichen , Zhu Jiadi , Liu Keqin , Xu Liying , Cai Yimao , Yan Xiaoqin , Yang Yuchao , Huang Ru
Published: September 2018

Neuromorphic engineering offers a promising route toward intelligent and low power computing systems that may find applications in artificial intelligence and the Internet. Construction of neuromorphic systems, however, requires scalable nanodevices that could implement the key functionalities of biological synapses. Here, we demonstrate an artificial synaptic device consisting of a Ti/yttria-stabilized-zirconia (ZrO2:Y)/Pt memristive structure, where the loss microstructure, high oxygen vacancy concentration, and resultant high ionic conductivity in ZrO2:Y facilitate the oxygen vacancy migration and filament evolution in the devices, leading to a bipolar artificial synapse with low forming and operation voltages. As the thickness of ZrO2:Y film increases, a transition from bipolar to unipolar resistive switching was observed, which can be ascribed to the competing vertical and radial ion transport dynamics. The emergence of unipolar switching has in turn allowed the device to exhibit metaplasticity, a history dependent plasticity that is important for memory and learning functions. This work thus demonstrates on-demand manipulation of ionic transport properties for building synaptic elements with rich functionalities.
Electric field driven memristive behavior at the Schottky interface of Nb-doped SrTiO3
Authors: Goossens A. S. , Das A. , Banerjee T.
Published: September 2018

Computing inspired by the human brain requires a massive parallel architecture of low-power consuming elements of which the internal state can be changed. SrTiO3 is a complex oxide that offers rich electronic properties; here, Schottky contacts on Nb-doped SrTiO3 are demonstrated as memristive elements for neuromorphic computing. The electric field at the Schottky interface alters the conductivity of these devices in an analog fashion, which is important for mimicking synaptic plasticity. Promising power consumption and endurance characteristics are observed. The resistance states are shown to emulate the forgetting process of the brain. A charge trapping model is proposed to explain the switching behavior.
Enhanced finite size and interface mixing effects in iridium manganese ultra thin films
Authors: Jenkins Sarah , Evans Richard F. L.
Published: September 2018

The finite size and temperature dependent properties of antiferromagnets are of critical importance to a wide range of spintronic and neuromorphic computing devices. Here we present atomistic simulations of IrMn, one of the most technologically important antiferromagnets, in both the ordered (L12) and disordered (γ) phases. We have found that antiferromagnetic IrMn3 films show a stronger finite size dependence of the Néel temperature than an equivalent ferromagnet due to the existence of spin frustration. We also find that the disordered γ-IrMn3 phase shows a dramatic reduction in the Néel temperature to less than room temperature for films less than 1 nm thick. Interfacial intermixing of the IrMn3 with a non-magnetic Cu capping layer further reduces the Néel temperature for a given film thickness, with a stronger influence on the disordered γ-IrMn3 phase compared to the ordered L12-IrMn3 phase. Our results suggest a larger antiferromagnetic film thickness is required for devices operating at or above room temperature compared to an equivalent ferromagnet, particularly for sputtered films with a high degree of interfacial intermixing.
Elastic properties of single crystal hydrogen sulfide: A Brillouin scattering study under high pressure-temperature
Authors: Zhou Di , Huang Xiaoli , Li Xin , Yu Hongyu , Li Fangfei , Huang Yanping , Lu Mengya , Liang Yongfu , Liu Mingkun , Wu Gang , Zhou Qiang , Liu Bingbing , Cui Tian
Published: September 2018

We have performed high pressure-temperature Brillouin scattering measurements on single crystal hydrogen sulfide using externally heated diamond anvil cell techniques. The pressure dependences of the acoustic velocities, isothermal elastic constants, and moduli of single crystal hydrogen sulfide have been determined along four isotherms. Both elastic constants and moduli increase monotonously with pressure along each isotherm, while they show a decreased tendency with temperature elevated under the same pressure points. The experimental equation of state of single crystal hydrogen sulfide is obtained by fitting with a third-order Birch-Murnaghan and Tait equation. It is proposed that the effect of hydrogen bonds contributes to the unique tendency of elastic anisotropy in single crystal hydrogen sulfide. Through our work, we have extended the melting curve and phase diagram of hydrogen sulfide up to 12 GPa and 580 K.
Gravitational thermal flows of liquid metals in 3D variable cross-section containers: Transition from low-dimensional to high-dimensional chaos
Authors: Lappa Marcello , Ferialdi Hermes
Published: September 2018

This study extends the numerical results presented in author's past work [M. Lappa and H. Ferialdi, Phys. Fluids 29(6), 064106 (2017)] about the typical instabilities of thermogravitational convection (the so-called Hadley flow) in containers with inclined (converging or diverging) walls. The flow is now allowed to develop along the third dimension (z). In a region of the space of parameters where the two-dimensional solutions were found to be relatively regular in time and with a simple structure in space (supporting transverse waves propagating either in the downstream or in the upstream direction), the 3D flow exhibits either waves traveling along the spanwise direction or spatially disordered and chaotic patterns. In order to identify the related mechanisms, we analyze the competition between hydrodynamic and hydrothermal (Oscillatory Longitudinal Roll) modes of convection for different conditions. A peculiar strategy of analysis is implemented, which, on the one hand, exploits the typical properties of systems developing coexisting branches of solutions (“multiple” states) and their sensitivity to a variation of the initial conditions and, on the other hand, can force such systems to select a specific category of disturbances (by enabling or disabling the related “physical” mechanisms). It is shown that hydrodynamic modes can produce early transition to chaos. The dimensionality of such states is investigated through evaluation of the “fractal” (correlation) dimension on the basis of the algorithm by Grassberger and Procaccia. When low-dimensional chaos is taken over by high-dimensional chaos, the flow develops a recognisable interval of scales where turbulence obeys the typical laws of the so-called “inertial range” and produces small-scale features in agreement with available Kolmogorov estimates.
Effective magnetic susceptibility of suspensions of ferromagnetic particles
Authors: Bai Kunlun , Casara Joshua , Nair-Kanneganti Aparna , Wahl Aubrey , Carle Florian , Brown Eric
Published: September 2018

The effective susceptibility χeff of suspensions of ferromagnetic particles in a liquid was measured using inductance measurements. These measurements were used to test a model that predicts how χeff varies due to demagnetization, as a function of sample aspect ratio, particle packing fraction, and particle aspect ratio [R. Skomski, G. C. Hadjipanayis, and D. J. Sellmyer, IEEE Trans. Magn. 43, 2956–2958 (2007)]. For spherical particles or cylindrical particles forcibly aligned with an external magnetic field, the model can be fitted to the measured data with agreement within 13%. This model predicts suspensions of aligned, large-aspect-ratio particles should have the largest χeff, approaching the particle material susceptibility in the limit of large particle aspect ratio. However, χeff was found to be no larger than about 4 for cylindrical iron particles of various aspect ratios, close to the value obtained for spheres. This results from the random alignment of non-spherical particles relative to the magnetic field naturally found in suspensions, which increases the demagnetization effect and limits χeff. The contribution of random particle alignments to the demagnetization effect and χeff remains to be accounted for in models.
A possible explanation of meta-magnetic transition in CeRu2Si2 and magnetic behavior in Gd-poor (Ce-Gd)Ru2Si2
Authors: Yano K. , Amakai Y. , Hara Y. , Sato K. , Kita E. , Takano H. , Ohta T. , Murayama S.
Published: September 2018

Aiming at getting any clue to the mechanism of characteristic behavior of meta-magnetic transition in CeRu2Si2 and the Ce 4f electronic states in Gd-poor contents, the (Ce-Gd)Ru2Si2 crystal mixed system was studied through magnetic measurements. A characteristic behavior of meta-magnetic transition observed in CeRu2Si2 was found to be reproduced in GdRu2Si2 in the temperature range between 30 K and 40 K. The meta-magnetic transition field was increased to higher field by the substitution of small amount of Gd contents of 0.01 and 0.02 at%. Furthermore, the reciprocal susceptibility in CeRu2Si2 (Gd=0) in temperature range between 15 K and 300 K revealed that the electronic state of Ce 4f was dominantly Ce3+, which was in accordance with a previous work, and the electronic states of Ce 4f in CeRu2Si2 could be described by the Van Vleck paramagnetic picture.
High density H2 and He plasmas: Can they be used to treat graphene?
Authors: Mehedi H.-A. , Ferrah D. , Dubois J. , Petit-Etienne C. , Okuno H. , Bouchiat V. , Renault O. , Cunge G.
Published: September 2018

Since graphene and other 2D materials have no bulk, a major issue is their sensitivity to surface contaminations, and the development of cleaning processes is mandatory. High density plasmas are attractive to treat (clean, dope, and pattern) 2D materials, because they are a mature industrial technology adapted to large area wafer. However, in these plasmas, the substrate is bombarded by a high flux of both thermal radicals and reactive ions with typical energy above 10 eV, which can easily damage atomic layer thin materials. We have investigated systematically the interaction of H2 and He inductively coupled plasmas (ICPs) with graphene in industrial reactors. We report a specific issue associated with the use of H2 plasma: they etch the inner part of plasma reactor walls, thus releasing impurities in the plasma, most notably O atoms that etch graphene and Si atoms which stick on it. The presence of parasitic oxygen presumably explains the discrepancies found in the literature regarding the impact of reactive plasmas on graphene damages. To get rid of this issue, we propose to use a fluorinated aluminum chamber. In this case, fluorine atoms which are shown to be harmless to graphene are the only impurity in the plasma. Under such conditions, H2 ICP plasma is shown to clean graphene without damages if the ion energy is kept below about 15 eV.
Enhancement of thermoelectric figure-of-merit of graphene upon BN-doping and sample length reduction
Authors: D’Souza Ransell , Mukherjee Sugata
Published: September 2018

Using first-principles density functional perturbation theory based calculations of length-dependent lattice thermal conductivity (κL) and using our previously calculated results [R. D’Souza and S. Mukherjee, Phys. Rev. B 95, 085435 (2017)] of electrical transport, we report results of thermoelectric figure-of-merit (ZT) of monolayer and bilayer graphene. We find a nearly tenfold increase in ZT for the graphene sample doped with boron nitride and reduced sample length. We also compare κL calculated using the iterative real space method with conventional analytical Callaway-Klemens method and obtain the flexural (ZA) phonon modes to be dominant in thermal transport unlike in the latter method. Our calculations are in good agreement with available experimental data.
The contribution of distinct response characteristics of Fe atoms to switching of magnetic anisotropy in Fe4N/MgO heterostructures
Authors: Li Z. R. , Mi W. B. , Bai H. L.
Published: September 2018

The modulation of magnetic anisotropy is very promising for the realization of energy-efficient memory devices. In this work, we investigate the effects of interfacial oxidation and electric field on the magnetic anisotropy of the Fe4N/MgO heterostructure using first-principles calculations. The Fe4N/MgO heterostructure exhibits in-plane magnetic anisotropy, while interfacial oxidation induces a perpendicular magnetic anisotropy. In addition, the electric field-controlled switching of magnetic anisotropy is achieved. The magnetic anisotropy of FeI and FeII atoms in Fe4N has distinct response characteristics to interfacial oxidation and electric field, where the FeII atom is more sensitive and its magnetic anisotropy is reversed from the in-plane to the out-of-plane direction. This suggests the tunability of magnetic anisotropy in the Fe4N/MgO heterostructure, which offers the possibility for further application of the Fe4N-based magnetic tunnel junction.
Multilayer phosphorene quantum dots in an electric field: Energy levels and optical absorption
Authors: Abdelsalam H. , Saroka V. A. , Lukyanchuk I. , Portnoi M. E.
Published: September 2018

Triangular and hexagonal multilayer phosphorene quantum dots with armchair and zigzag terminations are investigated with the orthogonal tight-binding model. The effect of increasing the number of layers is revealed. The obtained results show that in a small size multilayer quantum dot, the edge states are as sensitive to the out-of-plane external electric fields as the edge states in a single layer dot to the in-plane external electric fields. The investigated optical absorption cross sections show that armchair phosphorene quantum dots have a regular behavior which should be useful for infrared detectors. In particular, it was found that in hexagonal armchair phosphorene dots, absorption peaks can be increased, decreased, or totally removed from the low-energy region depending on the orientation of the applied electric field. The effect of spurious doping can suppress the transitions <0.4 eV, while the effect of the finite temperature is almost negligible.
Environmental oxidative aging of iron oxide nanoparticles
Authors: Bogart Lara K. , Blanco-Andujar Cristina , Pankhurst Quentin A.
Published: September 2018

The environmental aging of functional iron oxide nanomaterials, especially those used in biomedical applications, may have significant consequences for both their mechanism of action and their safety profile. However, to date, there has been no way to systematically measure this property, and the problem has been largely overlooked. We show here that a recently proposed “center of gravity” method for determining the composition of magnetite (Fe3O4) and maghemite (γ-Fe2O3) mixtures via 57Fe Mössbauer spectroscopy can be applied to the matter. We show that a long-established diffusion model can be used to characterize the oxidative aging process, yielding a parametric (and therefore predictive) description of the magnetite-to-maghemite oxidation processes occurring within the nanoparticles.
Ester-Derivatized indoles as fluorescent and infrared probes for hydration environments
Authors: Huang Xin-yue , You Min , Ran Guang-liu , Fan Hao-ran , Zhang Wen-kai
Published: September 2018

Tryptophan derivatives have long been used as site-specific biological probes. 4-Cyanotryptophan emits in the visible region and is the smallest blue fluorescent amino acid probe for biological applications. Other indole or tryptophan analogs may emit at even longer wavelengths than 4-cyanotryptophan. We performed FTIR, UV-Vis, and steady-state and time-resolved fluorescence spectroscopy on six ester-derivatized indoles in different solvents. Methyl indole-4-carboxylate emits at 450 nm with a long fluorescence lifetime, and is a promising candidate for a fluorescent probe. The ester-derivatized indoles could be used as spectroscopic probes to study local protein environments. Our measurements provide a guide for choosing ester-derivatized indoles to use in practice and data for computational modeling of the effect of substitution on the electronic transitions of indole.
Recent advances in multifunctional capsule catalysts in heterogeneous catalysis
Authors: Gao Xin-hua , Ma Qing-xiang , Zhao Tian-sheng , Bao Jun , Tsubaki Noritatsu
Published: September 2018

Capsule catalysts composed of pre-shaped core catalysts and layer zeolites have been widely used in the tandem reactions where multiple continuous reactions are combined into one process. They show excellent catalytic performance in heterogeneous catalysis, including the direct synthesis of middle isoparaffins or dimethyl ether from syngas, as compared to the conventional hybrid catalysts. The present review highlights the recent development in the design of capsule catalysts and their catalytic applications in heterogeneous catalysis. The capsule catalyst preparation methods are introduced in detail, such as hydrothermal synthesis method, dual-layer method, physically adhesive method and single crystal crystallization method. Furthermore, several new applications of capsule catalysts in heterogeneous catalytic processes are presented such as in the direct synthesis of liquefied petroleum gas from syngas, the direct synthesis of para-xylene from syngas and methane dehydroaromatization. In addition, the development in the design of multifunctional capsule catalysts is discussed, which makes the capsule catalyst not just a simple combination of two different catalysts, but has some special functions such as changing the surface hydrophobic or acid properties of the core catalysts. Finally, the future perspectives of the design and applications of capsule catalysts in heterogeneous catalysis are provided.