bluuebunny/crossref_metadata_2025 huggingface dataset:
Selectively tuning gas transport through ionic liquid filled graphene oxide nanoslits using an electric field
Authors: Ying Wen , Zhou Ke , Hou Quangang , Chen Danke , Guo Yi , Zhang Jun , Yan Youguo , Xu Zhiping , Peng Xinsheng
Published: June 2019

An external electric field selectively facilitates CO2 permeation through ionic liquid filled nanoslits of a graphene oxide membrane.
Thermoresponsive polysarcosine-based nanoparticles
Authors: Yu Huayang , Ingram Nicola , Rowley Jason V. , Parkinson Sam , Green David C. , Warren Nicholas J. , Thornton Paul D.
Published: June 2019

Polysarcosine modified with limited molar amounts of (N-(2-hydroxypropyl)methacrylamide) yields a block copolymer capable of forming thermoresponsive nanoparticles that are suitable for controlled release applications.
Facile p–n control, and magnetic and thermoelectric properties of chromium selenides Cr2+xSe3
Authors: Guo Quansheng , Berthebaud David , Ueda Jumpei , Tanabe Setsuhisa , Miyoshi Akinobu , Maeda Kazuhiko , Mori Takao
Published: June 2019

Both n- and p-type binary Cr2+xSe3 were prepared by composition tuning, aiming for thermoelectric applications near room temperature.
The Role of Prekindergarten Spanish in Predicting First-Grade English Word Reading Among Dual-Language Learners
Authors:   Language and Reading Research Consortium (LARRC), Mesa Carol , Yeomans-Maldonado Gloria
Published: June 2019

Purpose

The purpose of the current study was to examine the role that the 1st language, Spanish, at prekindergarten (pre-K) plays in predicting 2nd language (L2), English, word reading in 1st grade. In addition, it examines the role of conceptual vocabulary in predicting word reading in English.

Method

As part of a longitudinal study of predictors and models of reading comprehension from pre-K to 3rd grade, 248 children attending preschool programs completed Spanish and English measures in the spring of each academic year. In this article, we report the results of English and Spanish measures of oral language and literacy skills that were administered in pre-K and 4 measures of English word reading that were administered in 1st grade.

Results

Results from structural equation modeling indicated that Spanish oral language made significant direct and indirect contributions to English oral language and word reading. Further, results supported previous evidence indicating that L2 letter knowledge and L2 oral language proficiency are the strongest predictors of L2 word reading in 1st grade.

Discussion

Similar to findings with monolingual English-speaking children, results support findings that, in the early stages of reading development, oral language in both 1st language and L2 make a significant and independent contribution to word reading. This study has important implications for the support of oral language skills in Latino preschool children.
X-ray spectra of the Fe-L complex
Authors: Gu Liyi , Raassen A. J. J. , Mao Junjie , de Plaa Jelle , Shah Chintan , Pinto Ciro , Werner Norbert , Simionescu Aurora , Mernier François , Kaastra Jelle S.
Published: June 2019

The Hitomi results on the Perseus cluster have led to improvements in our knowledge of atomic physics that are crucial for the precise diagnostic of hot astrophysical plasma observed with high-resolution X-ray spectrometers. However, modeling uncertainties remains, both within but especially beyond Hitomi’s spectral window. A major challenge in spectral modeling is the Fe-L spectrum, which is basically a complex assembly ofn ≥ 3 ton = 2 transitions of Fe ions in different ionization states, affected by a range of atomic processes such as collisional excitation, resonant excitation, radiative recombination, dielectronic recombination, and innershell ionization. In this paper we perform a large-scale theoretical calculation on each of the processes with the flexible atomic code (FAC), focusing on ions of Fe XVIIto Fe XXIVthat form the main body of the Fe-L complex. The calculation includes a large set of energy levels with a broad range of quantum numbernandl, taking into account the full-order configuration interaction and all possible resonant channels between two neighboring ions. The new data are found to be consistent within 20% with the recent individualR-matrix calculations for the main Fe-L lines, although the discrepancies become significantly larger for the weaker transitions, in particular for Fe XVIII, Fe XIX, and Fe XX. By further testing the new FAC calculations with the high-quality RGS data from 15 elliptical galaxies and galaxy clusters, we note that the new model gives systematically better fits than the current SPEX v3.04 code, and the mean Fe abundance decreases by 12%, while the O/Fe ratio increases by 16% compared with the results from the current code. Comparing the FAC fit results to those with theR-matrix calculations, we find a temperature-dependent discrepancy of up to ∼10% on the Fe abundance between the two theoretical models. Further dedicated tests with both observed spectra and targeted laboratory measurements are needed to resolve the discrepancies, and ultimately to get the atomic data ready for the next high-resolution X-ray spectroscopy mission.
Analysis of putative exoplanetary signatures found in light curves of two sdBV stars observed by Kepler
Authors: Blokesz A. , Krzesinski J. , Kedziora-Chudczer L.
Published: June 2019

Context. We investigate the validity of the claim that invokes two extreme exoplanetary system candidates around the pulsating B-type subdwarfs KIC 10001893 and KIC 5807616 from the primary Kepler field.

Aims. Our goal was to find characteristics and the source of weak signals that are observed in these subdwarf light curves.

Methods. To achieve this, we analyzed short- and long-cadence Kepler data of the two stars by means of a Fourier transform and compared the results to Fourier transforms of simulated light curves to which we added exoplanetary signals. The long-cadence data of KIC 10001893 were extracted from CCD images of a nearby star, KIC 10001898, using a point spread function reduction technique.

Results. It appears that the amplitudes of the Fourier transform signals that were found in the low-frequency region depend on the methods that are used to extract and prepare Kepler data. We demonstrate that using a comparison star for space telescope data can significantly reduce artifacts. Our simulations also show that a weak signal of constant amplitude and frequency, added to a stellar light curve, conserves its frequency in Fourier transform amplitude spectra to within 0.03 μHz.

Conclusions. Based on our simulations, we conclude that the two low-frequency Fourier transform signals found in KIC 5807616 are likely the combined frequencies of the lower amplitude pulsating modes of the star. In the case of KIC 10001893, the signal amplitudes that are visible in the light curve depend on the data set and reduction methods. The strongest signal decreases significantly in amplitude when KIC 10001898 is used as a comparison star. Finally, we recommend that the signal detection threshold is increased to 5σ (or higher) for a Fourier transform analysis of Kepler data in low-frequency regions.
The TeV-emitting radio galaxy 3C 264
Authors: Boccardi B. , Migliori G. , Grandi P. , Torresi E. , Mertens F. , Karamanavis V. , Angioni R. , Vignali C.
Published: June 2019

Context.In March 2018, the detection by VERITAS of very-high-energy emission (VHE >  100 GeV) from 3C 264 was reported. This is the sixth, and second most distant, radio galaxy ever detected in the TeV regime.

Aims.In this article we present a radio and X-ray analysis of the jet in 3C 264. We determine the main physical parameters of the parsec-scale flow and explore the implications of the inferred kinematic structure for radiative models of thisγ-ray emitting jet.

Methods.The radio data set is comprised of VLBI observations at 15 GHz from the MOJAVE program, and covers a time period of about two years. Through a segmented wavelet decomposition method (WISE code), we estimated the apparent displacement of individual plasma features; we then performed a pixel-based analysis of the stacked image to determine the jet shape. The X-ray data set includes all available observations from theChandra, XMM, andSwiftsatellites, and is used, together with archival data in the other bands, to build the spectral energy distribution (SED).

Results.Proper motion is mostly detected along the edges of the flow, which appears strongly limb brightened. The apparent speeds increase as a function of distance from the core up to a maximum of ∼11.5 c. This constrains the jet viewing angle to assume relatively small values (θ ≲ 10°). In the acceleration region, extending up to a de-projected distance of ∼4.8 × 104Schwarzschild radii (∼11 pc), the jet is collimating (r ∝ z0.40 ± 0.04), as predicted for a magnetically-driven plasma flow. By assuming that the core region is indeed magnetically dominated (UB/Ue >  1), the SED and the jet power can be well reproduced in the framework of leptonic models, provided that the high-energy component is associated to a second emitting region. The possibility that this region is located at the end of the acceleration zone, either in the jet layer or in the spine, is explored in the modeling.
Integrals of motion for non-axisymmetric potentials
Authors: Bienaymé O.
Published: June 2019

Context. The modelling of stationary galactic stellar populations can be performed using distribution functions.

Aims. This paper aims to write explicit integrals of motion and distribution functions.

Methods. We propose an analytic formulation of the integrals of motion with an explicit dependence on potential. This formulation applies to potentials with rotational symmetry or triaxial symmetry. It is exact for Stäckel potentials and approximate for other potentials.

Results. Modelling a stationary stellar population using these integrals of motion allows the force field to be found with satisfactory accuracy. On the other hand, the mass density distribution that generates the force field and the gravitational potential is recovered with less accuracy due to lower precision in modelling box-type orbits.
Prompt Fission Neutron Investigation in 235U(nth,f) and 252Cf(sf) Reactions
Authors: Zeynalov Shakir , Sedyshev Pavel , Shvetsov Valery , Sidorova Olga
Published: June 2019

The prompt neutron emission in thermal neutron induced fission of 235U and spontaneous fission of 252Cf was investigated by using digital signal electronics. The goal was to check a new revised data analysis software with fission fragment (FF) kinetic energy corrections after prompt fission neutron (PFN) emission. The revised software was used to reanalyze old data measured in EC-JRC-IRMM, where 252Cf(sf) reaction was investigated. Both measurements were done using similar twin Frisch grid ionization chamber for fission fragment detection with equivalent NE213 fast neutron detector. About 0.5*106 FF with PFN coincidences have been analyzed in both measurements. The fission fragment kinetic energy, mass and angular distribution were investigated along with prompt neutron time of flight and pulse shape analysis using a six channel synchronous waveform digitizer (WFD) with sampling frequency of 250 MHz and 12 bit resolution in the 235U(nth,f) reaction. Similar WFD with sampling frequency of 100 MHz was used for PFN investigation in 252Cf(sf) reaction. These two experiments were considered as a reference for further investigations with a new setup composed of position sensitive ionization chamber to detect FF and an array of 32 liquid scintillators recently constructed in Dubna to detect neutrons.
Current status of the verification and processing system GALILÉE-1 for Evaluated Data
Authors: Coste-Delclaux Mireille , Jouanne Cédric , Moreau Frédéric , Mounier Claude , Visonneau Thierry , Malouch Fadhel
Published: June 2019

This paper describes the current status of GALILÉE-1 that is the new verification and processing system for evaluated data, developed at CEA. It consists of various components respectively dedicated to read/write the evaluated data whatever the format is, to diagnose inconsistencies in the evaluated data and to provide continuous-energy and multigroup data as well as probability tables for transport and depletion codes. All these components are written in C++ language and share the same objects. Cross-comparisons with other processing systems (NJOY, CALENDF or PREPRO) are systematically carried out at each step in order to fully master possible discrepancies. Some results of such comparisons are provided.
Monte Carlo integral adjustment of nuclear data libraries – experimental covariances and inconsistent data
Authors: Sjöstrand Henrik , Schnabel Georg
Published: June 2019

Integral experiments can be used to adjust nuclear data libraries. Here a Bayesian Monte Carlo method based on assigning weights to the different random files is used. If the experiments are inconsistent within them-self or with the nuclear data it is shown that the adjustment procedure can lead to undesirable results. Therefore, a technique to treat inconsistent data is presented. The technique is based on the optimization of the marginal likelihood which is approximated by a sample of model calculations. The sources to the inconsistencies are discussed and the importance to consider correlation between the different experiments is emphasized. It is found that the technique can address inconsistencies in a desirable way.
Fortbildungsbedarf auf einer neonatologischen und
pädiatrischen Intensivstation
Authors: Weingärtner Carolien , Koch Sebastian
Published: June 2019

Man lernt nie aus, weiß schon der Volksmund. Gerade in der Pflege hat dieser
Spruch eine große Bedeutung. Doch wie lässt sich ein lebenslanges Lernen im
Berufsalltag umsetzen? In welcher Form kann das Vermitteln von Wissen
stattfinden? Und wie sieht es dabei mit der Motivation der Pflegenden aus?
Early metabolic response assessment of breast cancer liver
metastases: 4-week posttreatment FDG PET predicts survival after 90Y
microsphere radioembolization
Authors: Sabet Amir , Ries Martin , Al-Khalaf Yamen , Meyer Carsten , Rudlowski Christian , Simon Birgit , Khreish Fadi , Ezziddin Samer
Published: June 2019

Aim To evaluate the feasibility of early metabolic response assessment
with 18F-FDG PET/CT in patients with breast cancer liver metastases 4
weeks after radioembolization with Yttrium-90 labeled microspheres.

Methods 25 patients (mean age 58y, range 40–74) with advanced stage liver
metastases of breast cancer were treated with 1.9 ± 0.4 GBq of 90Y-microspheres
in the salvage setting and underwent 18F-FDG PET/CT at baseline and 4
weeks post-radioembolization. 14 patients (56 %) had an excessive hepatic tumor
burden (> 50 % of total liver volume), 21 patients (84 %) had extrahepatic
disease. Liver lesions with the highest SUVmax were selected as
target lesions and a cut-off was set at 50 % reduction to separate responders
from non-responders. The predictive impact of metabolic response on overall
survival (OS) was investigated along with other prognostic factors.

Results The median OS in this highly advanced metastatic cohort was 7
months (95 % CI, 5–9). All patients had a reduction in SUVmax (mean
ΔSUVmax: –49 ± 26 %) at 4 weeks post-treatment. Patients with
> 50 % SUVmax reduction survived longer (median OS 13 mo, 95 % CI
8–18) than the remaining patients (median OS 4 mo, 95 % CI 2–6; p = 0.001). From
all investigated baseline factors including age, performance status, and
presence of extra-hepatic disease, only the hepatic tumor burden had a
significant impact on OS (p = 0.02).

Conclusions This is the first preliminary evidence in breast cancer that
early post-radioembolization molecular response assessment of treated liver
metastases – as early as 4 weeks posttreatment – may predict survival. If
confirmed by larger series, FDG PET/CT could be considered for early
response-adapted treatment modifications.
Tablet-basiertes Trainingsmodell zum Verständnis des
Zusammenwirkens von extrinsischer Unterarmmuskulatur und intrinsischer
Handmuskulatur
Authors: Andreou Andreas , Ganser Joachim
Published: June 2019

Das Zusammenwirken verschiedener Muskeln in der Ausführung spezieller Handgriffe
ist komplizierter als gedacht. Wir haben deshalb ein Tablet-basiertes
Trainingsmodell entworfen, um zur selbständigen Komposition spezifischer
Handgriffe unter gewichtetem Einsatz der zur Verfügung stehenden Instrumente,
d. h. der extrinsischen und intrinsischen Unterarm- und Handmuskeln zu
animieren. Unsere Lösungen für die gestellten Aufgaben erheben keinen Anspruch
auf Richtigkeit, da es eine entsprechende validierte Datenbank noch nicht gibt.
Wir möchten mit dem Modell lediglich zur Weiterbildung und zum Spaß in der
täglichen Arbeit beitragen.
Edgeworthia papyrifera Regulates Osteoblast and Osteoclast Differentiation In Vitro and Exhibits Anti-osteoporosis Activity in Animal Models of Osteoporosis
Authors: Kim Pansoo , Nam Yeon-Ju , Kim Woo Jung , Kim Jin Kyu , Lee Gyeongbeen , Song Myung-Jin , Yang Jungeun , Yi Sun Shin , Lee Jong Suk , Seo Jin-Ho , Choi Yongmun
Published: June 2019

Osteoporosis is a clinical condition characterized by low bone strength that leads to an increased risk of fracture. Strategies for the treatment of osteoporosis involve inhibition of bone resorption by osteoclasts and an increase of bone formation by osteoblasts. Here, we identified the extract derived from the stem part of Edgeworthia papyrifera that enhanced differentiation of MC3T3-E1 cells to osteoblast-like cells and inhibited osteoclast differentiation of RAW 264.7 cells in vitro. In support of our observation, rutin and daphnoretin, which were previously reported to inhibit osteoclast differentiation, were identified in E. papyrifera extract. In an animal model of osteoporosis, the ovariectomy-induced increases in bone resorption biomarkers such as pyridinoline and tartrate-resistant acid phosphatase were significantly reduced by E. papyrifera extract administration at 25.6 and 48.1%, respectively. Furthermore, the ovariectomy-induced bone loss in animal models of osteoporosis was significantly prevented by the administration of E. papyrifera in our study. Taking these observations into account, we suggest that E. papyrifera is an interesting candidate for further exploration as an anti-osteoporotic agent.
Development of a Hydrazine-Catalyzed Carbonyl-Olefin Metathesis Reaction
Authors: Lambert Tristan H.
Published: June 2019

Carbonyl-olefin metathesis is a potentially powerful yet underexplored reaction in organic synthesis. In recent years, however, this situation has begun to change, most notably with the introduction of several different catalytic technologies. The development of one of those new strategies, based on hydrazine catalysts and a novel [3+2] paradigm for double bond metathesis, is discussed herein. First, the stage is set with a description of some potential applications of carbonyl-olefin metathesis and a discussion of alternative strategies for this intriguing reaction.

1 Introduction

2 Potential Applications of Carbonyl-Olefin Metathesis

3 Carbonyl-Olefin Metathesis Strategies

4 Direct (Type I): Non-Catalytic

5 Direct (Type I): Acid-Catalyzed

6 Indirect (Type II): Metal Alkylidenes

7 Indirect (Type III): Hydrazine-Catalyzed

8 Conclusion
A Quantitative and Qualitative Analysis of Electronic Prescribing Incidents Reported by Community Pharmacists
Authors: Hincapie Ana L. , Alamer Ahmad , Sears Julie , Warholak Terri L. , Goins Semin , Weinstein Sara Danielle
Published: June 2019

Background Electronic prescribing (e-prescribing) technology was introduced as an alternative to handwritten prescriptions allowing health care professionals to send prescriptions directly to pharmacies. While the technology has many advantages, such as improving pharmacy workflow and reducing medication errors, some limitations have been realized.

Objective The objective of this study was to examine the frequency, type, and contributing factors of e-prescribing quality-related incidents reported to two national error-reporting databases in the United States.

Methods This was a retrospective analysis of voluntarily reports of e-prescribing quality-related incidents. A quantitative and qualitative analysis was conducted of incidents reported between 2011 and 2015 to the Pharmacy Quality Commitment (PQC) and the Pharmacy Provider e-prescribing Experience Reporting Portal (PEER) databases. For the qualitative analysis, events were combined from the PQC and PEER portal and a 10% random sample of events were analyzed.

Results A total of 589 events were reported to the PEER Portal. Of these, problems with patient directions were the most frequent incident type (n = 210) of which 10% (n = 21) reached the patient. Quantity selection (n = 158) and drug selection (n = 96) were the next most frequently reported events, 20% of which reached the patient. The PQC system received 550 reports. The most frequent event type reported to this system was incorrect directions (23.3%, n = 128) followed by incorrect prescriber (17%), incorrect drug (15%), and incorrect strength (12%). The most common theme in the qualitative analysis was a perceived increased likelihood of patient receiving incorrect drug therapy due to e-prescribing. Another theme identified included confusion and frustration of pharmacy personnel as result of e-prescription quality-related events.

Conclusion The use of qualitative and quantitative incident data revealed that patient directions and quantity selection were the most common quality issues with e-prescribing. In turn, this may increase the likelihood of patients receiving incorrect drug therapy.
Neonates Effects and Tolerability of Treprostinil in Hypertension with Persistent Pulmonary
Authors: Jozefkowicz Mariela , Haag Dora Fabiana , Mazzucchelli María Teresa , Salgado Gladys , Fariña Diana
Published: June 2019

Objective The aim of this study was to establish the effects of treprostinil in congenital diaphragmatic hernia (CDH) patients with persistent pulmonary hypertension (PHT) after 1 week of treatment. Drug effects were assessed by oxygenation index (OI), clinical end points, serial biochemical markers, and pre- and posttreatment echocardiogram. Treatment complications were also described.

Study Design This is a quasi-experimental study of neonates with PHT admitted to the NICU within 48 hours showing persistent clinical instability, receiving mechanical ventilation with FiO2 > 60%, milrinone therapy, and inhaled nitric oxide. Clinical data were compared before and after treprostinil treatment.

Results Seventeen neonates met the inclusion criteria. Median age was 17 days. Before treatment, median OI was 20 (IQR: 12–27). Suprasystemic PHT was estimated by echocardiogram in 8/17 patients; the rest were systemic. After 1 week of treatment, 15/17 patients were alive and median OI was 8 (IQR: 5–12, p = 0.0089). There were no statistically significant changes in laboratory data. Echocardiogram still showed suprasystemic PHT in 20% of patients. Adverse effects included hypotension, hematoma at the infusion site, and surgical persistent ductus arteriosus (PDA) closure in 4/17 patients. Fourteen patients were discharged. The median treatment time was 61 days.

Conclusion Treprostinil was well tolerated with satisfactory clinical response. Further studies are required to identify early responder subgroups.
Management of Breech Presentation: A Comparison of Four National Evidence-Based Guidelines
Authors: Tsakiridis Ioannis , Mamopoulos Apostolos , Athanasiadis Apostolos , Dagklis Themistoklis
Published: June 2019

Objective The management of breech presentation may improve perinatal outcomes. The aim of this study was to synthesize and compare published evidence of four national guidelines on breech presentation.

Study Design A descriptive review of four recently published national guidelines on breech presentation and external cephalic version (ECV) was conducted: Royal College of Obstetricians and Gynaecologists guideline on “External Cephalic Version and Reducing the Incidence of Term Breech Presentation” and “Management of Breech Presentation”, American College of Obstetricians and Gynecologists guideline on “External Cephalic Version” and “Mode of Term Singleton Breech Delivery,” Society of Obstetricians and Gynaecologists of Canada guideline on “Vaginal Delivery of Breech Presentation” and the Royal Australian and New Zealand College of Obstetricians and Gynaecologists guideline on “Management of breech presentation at term.”

Results Regarding ECV, there is no recommendation by the SOGC, whereas all other national guidelines recommend this technique. Regarding breech vaginal delivery, there are limited recommendations by the ACOG, whereas all other guidelines provide similar recommendations. The RANZCOG makes no special recommendations on the intrapartum period.

Conclusion The differences among national guidelines point out the need for the adoption of an international consensus on the management of breech presentation.
Invariant behavior of stochastic atmosphere-ocean model with degenerate noise
Authors: Wang Pin , Chen Guanggan
Published: June 2019

This work is concerned with the invariant behavior of a stochastic atmosphere-ocean model with the degenerate noise, which describes the climate and geophysical phenomena. Through introducing a transform to deal with the complicated boundary conditions, first, the existence of the invariant measure is established. Since the degenerate noise only drives the latitudinal atmosphere surface temperature, it then proposes to combine the strong Feller property with the asymptotically strong Feller and the irreducibility to verify the uniqueness of the invariant measure. It further implies the ergodicity of the system.
Simulations of supercooled water under passive or active stimuli
Authors: Teboul Victor , Rajonson Gabriel
Published: June 2019

We use molecular dynamics simulations to study the behavior of supercooled water subject to different stimuli from a diluted azobenzene hydrophobic probe. When the molecular motor does not fold, it acts as a passive probe, modifying the structure of water around it, while when the motor is active, it induces elementary diffusion processes inside the medium acting mainly on the dynamics. We study two particular densities, the density of ambient water and a lower density around the ambient pressure ice density, chosen to favor high density liquid and low density liquid (LDL) water, respectively. We find that the passive probe induces ever an acceleration or a slowing down of the diffusion process around it depending on the density of water, while the active probe induces acceleration only. We find a crossover between the diffusion coefficients for the two densities near the passive probe, around T = 215 K. This dynamical crossover is associated with a modification of the structure of water near the probe. Structure calculations show a crossover of the proportion of LDL water around the same temperature, suggesting that it induces the observed dynamical crossover. In opposition with these results, the active stimuli increase diffusion for both densities and decrease the proportion of LDL water at low temperatures. However, we also find for the active stimuli a crossover of the LDL proportion between the two densities of study, showing remarkable similarities between active and passive stimulus results.
A mesoscale study on explosively dispersed granular material using direct simulation
Authors: Mo Huangrui , Lien Fue-Sang , Zhang Fan , Cronin Duane S.
Published: June 2019

Explosively dispersed granular materials frequently exhibit coherent particle clustering and jetting structures. Influencing the mass concentration and related particle reaction and energy release, this phenomenon is of significant interest to the study of flow instability and mixing in heterogeneous detonation and explosion. Largely inhibited by the complex mesoscale multiphase interactions involved in the dispersal process, the underlying mechanism remains unclear. In this study, mesoscale direct simulations that capture coupled multiphase interactions and deterministic granular dynamics are conducted to investigate particle clustering and jetting formation in explosively dispersed granular payloads consisting of inert particles. Employing a mesoscale simulation framework that models particles as discrete entities and resolves the interfaces and collisions of individual particles in stochastically generated payloads with randomly distributed particle positions and sizes, numerical cases that cover a set of stochastic payloads, burster states, and coefficients of restitution are solved and analyzed. A valid statistical dissipative property of the mesoscale discrete modeling with respect to Gurney velocity is demonstrated. The predicted surface expansion velocities can extend the time range of the velocity scaling law with regard to Gurney energy in the Gurney theory from the steady-state termination phase to the unsteady evolution phase. Dissipation analysis based on the mesoscale discrete modeling of granular payloads suggests that incorporating the effects of porosity can enhance the prediction of Gurney velocity for explosively dispersed granular payloads. On the basis of direct simulations, an explanation for particle clustering and jetting formation is proposed to increase the understanding of established experimental observations in the literature.
Diffusion of large particles through small pores: From entropic to enthalpic transport
Authors: Bodrenko Igor V. , Salis Samuele , Acosta-Gutierrez Silvia , Ceccarelli Matteo
Published: June 2019

We present a statistical model for solving and predicting the transport of large molecules through small flexible channels. The average radius of the channel and the average radius of the molecule are the only two quantities determining the steric part of the potential of mean force for the translocation, in the case of a small rigid particle and a large rigid channel: the barrier is completely entropic and is described by the Fick-Jacobs model. However, the flexibility of the channel’s cross section and that of the molecule’s size have a significant effect on transport, especially when a large molecule goes through a narrow channel. In this case, the steric barrier changes its statistical nature becoming enthalpic, and we predict a strong temperature enhancement of the diffusion current through the channel. The flexibility is described in terms of the equilibrium fluctuations of the channel and of the molecule. The model is compared with the all-atom MD simulations of the transport of hard spheres of various radii and of drug molecules through a biological nanochannel. For the case of Gaussian fluctuations, we derived a simple analytical expression for the steric barrier, which can be quantified using average size and fluctuations of the channel and of the molecule.
Experimental and numerical study on the drainage performance and fluid flow of Venturi tubes
Authors: Zhang Junxia , Yuan Wenhua , Chen Zhigang , Wang Zehua
Published: June 2019

Venturi tubes have been widely applied to the mixture and drainage of fluid due to the Venturi effect. In this work, an experimental investigation and a numerical simulation are conducted to analyze the fluid flow processing and drainage performance of Venturi tubes. A Venturi experimental installation is also established, and it consists of stainless steel and Plexiglas venturi tubes, pressure gauges, and flowmeters. The relationship between pressure evolution and volume flux is experimentally measured during the fluid flow proceeding in the Venturi tubes. Fluent software is used to model the optimization of drainage efficiency in the Venturi tube. Pressure is found to increase as the volume flux of the working fluid ascends. In a contraction section, the static pressure is transformed into the velocity of fluid, and the static pressure drops. In a diffusion section, the velocity of fluid is transformed into the static pressure, and the static pressure improves. A gas–water stratification phenomenon easily occurs; that is, the gas–water stratification region moves backward as the volume flux of the working fluid increases. Numerical results show that the drainage efficiency first increases and then decreases as the diameters of the throat and drainage tubes and the diffusion angle increase. When the diameter of the throat, drainage, and diffusion tubes are 48, 18, and 70 mm to 79 mm, respectively, the drainage efficiency is in a steady state and reach 0.5, which is significantly higher than the reported value of 0.2 from the reference. Drainage efficiency shows an M-shaped change as the drainage location varies. Setting a drainage tube in the contraction section is helpful in drainage; the diameter of the drainage tube is 17.5–18.5 mm.
“Hot electrons in Si lose energy mostly to optical phonons”: Truth or myth?
Authors: Fischetti M. V. , Yoder P. D. , Khatami M. M. , Gaddemane G. , Van de Put M. L.
Published: June 2019

Theoretical studies of heat generation and diffusion in Si devices generally assume that hot electrons in Si lose their energy mainly to optical phonons. Here, we briefly review the history of this assumption, and using full-band Monte Carlo simulations—with electron-phonon scattering rates calculated using the rigid-ion approximation and both empirical pseudopotentials and Harris potentials—we show that, instead, electrons lose as much as 2/3 of their energy to acoustic phonons. The scattering rates that we have calculated have been used to study hot-electron effects, such as impact ionization and injection into SiO2, and are in rough agreement with those obtained using density functional theory. Moreover, direct subpicosecond pump-probe experimental results, some of them dating back to 1994, are consistent with the predictions of our model. We conclude that the study of heat generation and dissipation in nanometer-scale Si devices may require a substantial revision of the assumptions that have been considered “common wisdom” so far.
Stimulated emission, photoluminescence, and localisation of nonequilibrium charge carriers in ultrathin (monolayer) GaN/AlN quantum wells
Authors: Lutsenko E.V. , Rzheutski M.V. , Nagorny A.V. , Danilchyk A.V. , Nechaev D.V. , Jmerik V.N. , Ivanov S.V.
Published: June 2019

The stimulated emission and photoluminescence of ultrathin GaN quantum wells with a nominal thickness of 1.5 – 2 monolayers (MLs) and AlN barrier layers 4 – 6.66 ML thick, obtained by plasma-activated molecular beam epitaxy on c-sapphire substrates, are studied. The stimulated emission of TE polarisation in ultrathin GaN/AlN quantum wells is obtained under pumping directly into quantum wells. The wavelength of stimulated emission varied from 262 to 290 nm, depending on the thickness of the wells and barriers. It is shown that stimulated emission is achieved on localised GaN states with a thickness of 2 and 3 ML in ultrathin quantum wells with a nominal thickness of 1.5 and 2 ML, respectively. The minimum excitation threshold of stimulated emission was 700 kW cm−2 at λ = 270 nm.
Electronic and optical properties of hybrid GaN/por-Si(111) heterostructures
Authors: Seredin P.V. , Goloshchapov D.L. , Zolotukhin D.S. , Lenshin A.S. , Mizerov A.M. , Arsent’ev I.N. , Leiste H. , Rinke M.
Published: June 2019

Using plasma-assisted molecular beam epitaxy (PA MBE) of nitrogen, we obtained integrated heterostructures based on a self-ordered array of GaN nanocolumns on Si substrates with a sufficiently uniform distribution of diameters, which subsequently coalesced into a 2D layer. The use of a ‘compliant’ por-Si substrate for GaN synthesis using PA MBE allowed us to obtain a crack-free GaN layer, prevent the Ga-Si etching process, maintain a sharp smooth Si – GaN interface, and also partially suppress the generation of tensile stresses caused by cooling the heterostructure from growth temperature to room temperature by its relaxation at the Si – GaN nanoporous interface, which had a positive effect on its optical properties in the UV region.
Effect of (Al)GaAs/AlGaAs quantum confinement region parameters on the threshold current density of laser diodes
Authors: Ladugin M.A. , Marmalyuk A.A.
Published: June 2019

An approach has been proposed for choosing parameters (width and depth) of an (Al)GaAs/AlGaAs quantum confinement region via calculation of the threshold current density of a semiconductor laser. A detailed assessment of its components has made it possible to find criteria for optimising the range of quantum well widths so as to minimise the threshold current for lasers with different heterostructure geometries. The data presented in this paper demonstrate the feasibility of further improving output characteristics of semiconductor lasers by optimising the design and technology of quantum well heterostructures. Owing to this, we have simultaneously reduced the threshold current, carrier escape and internal optical loss, which has allowed us to obtain high (60 % to 70 %) efficiencies of a semiconductor laser operating in the spectral range 800 – 850 nm.
Quantum dot lasers with asymmetric barrier layers: Close-to-ideal threshold and power characteristics
Authors: Asryan L.V.
Published: June 2019

A theory of static (threshold and power) characteristics of novel diode lasers – quantum dot (QD) lasers with asymmetric barrier layers (ABLs) – is developed. The barrier layers are asymmetric in that they have considerably different heights for the carriers of opposite signs. The ABL located on the electron- (hole-) injecting side of the structure provides a low barrier (ideally no barrier) for electrons (holes) [so that it does not prevent electrons (holes) from easily approaching the active region] and a high barrier for holes (electrons) [so that holes (electrons) injected from the opposite side of the structure do not overcome it]. The use of ABLs should thus ideally prevent the simultaneous presence of electrons and holes (and hence parasitic electron – hole recombination) outside the QDs. It is shown in this work that in such a case of total suppression of parasitic recombination, the QD lasers with ABLs offer close-to-ideal performance: the threshold current density is below 10 A cm−2 at any temperature, the absolute value of the characteristic temperature is above 1000 K (which manifests a virtually temperature-independent operation), the internal differential quantum efficiency is practically unity, and the light – current characteristic is linear at any pump current.
Governance tools for the conservation of wetlands: the role of the Montreux Record under the Ramsar Convention
Authors: Hamman Evan , Van Geelen Tess , Akhtar-Khavari Afshin
Published: June 2019

The Ramsar Convention is the world’s most important international treaty governing wetland environments. Since the 1970s, the Convention has concerned itself with listing and protecting wetlands of international significance. However, in the past three decades, a focus has shifted from the identification of potential sites, towards addressing adverse changes in their ‘ecological character’. One of the few mechanisms Ramsar has at its disposal for achieving this is the Montreux Record (MR). The MR, first established in 1990, is a kind of ‘in danger’ list for Ramsar sites that have undergone, are undergoing, or are likely to undergo, adverse ecological change. Unlike other in-danger lists, such as, for example, under the World Heritage Convention, the MR is entirely voluntary and not deployed as a disciplinary measure or reputational sanction. The empirical research presented in this paper shows the declining use and importance of the MR. The paper provides an analysis of the composition and use of the MR from 1990 to 2018 and generates recommendations for how it might be used more effectively. The findings in this paper are significant, given the rapid declines of many Ramsar sites around the world.
Effect of Zn addition on two-step aging behaviour of Al–Mg–Si–Cu alloy
Authors: Zhu Shang , Li Zhihui , Yan Lizhen , Li Xiwu , Huang Shuhui , Yan Hongwei , Zhang Yongan , Xiong Baiqing
Published: June 2019

This study investigates the effect of Zn addition two-step behaviour in an Al–Mg–Si–Cu alloy. During pre-aging at 100°C for 3 h, the Zn can partition into clusters because of the strong Zn–Mg interaction, prompting the formation of clusters. During subsequent artificial aging at 180°C for up to 240 min (peak hardness condition), the Zn does not significantly partition into clusters or precipitates, and the majority of Zn remains in the Al matrix. However, the presence of Zn in the matrix stimulates the transformation from clusters to GP zones to β′′ phases. The enhanced formation of GP zones and β′′ phases correlates well with the remarkable age-hardening response.
A metasurface comprising spiral shaped local resonators for surface acoustic waves
Authors: Kyrimi V , Ash B J , Nash G R
Published: June 2019

The interaction of Rayleigh waves, propagating on lithium niobate, with a metasurface consisting of a square array of spiral-like vertical oscillators is investigated. We observe confinement of the acoustic energy throughout the height of the oscillators and note that this confinement also takes place at relatively low frequencies compared to circularly symmetric resonators of similar dimensions. A transmission study reveals that the bandgap attenuation is large (~25 dB) at both high and low frequencies, a characteristic that could be exploited in the design of new RF filters.
Atomically thin α-In2Se3: an emergent two-dimensional room temperature ferroelectric semiconductor
Authors: Li Yue , Gong Ming , Zeng Hualing
Published: June 2019

Room temperature ferroelectric thin films are the key element of high-density nonvolatile memories in modern electronics. However, with the further miniaturization of the electronic devices beyond the Moore’s law, conventional ferroelectrics suffer great challenge arising from the critical thickness effect, where the ferroelectricity is unstable if the film thickness is reduced to nanometer or single atomic layer limit. Two-dimensional (2D) materials, thanks to their stable layered structure, saturate interfacial chemistry, weak interlayer couplings, and the benefit of preparing stable ultra-thin film at 2D limit, are promising for exploring 2D ferroelectricity and related device applications. Therefore, it provides an effective approach to overcome the limitation in conventional ferroelectrics with the study of 2D ferroelectricity in van der Waals (vdW) materials. In this review article, we briefly introduce recent progresses on 2D ferroelectricity in layered vdW materials. We will highlight the study on atomically thin α-In2Se3, which is an emergent ferroelectric semiconductor with the coupled in-plane and out-of-plane ferroelectricity. Furthermore, two prototype ferroelectric devices based on ferroelectric α-In2Se3 will also be reviewed.
Growth of oxidation-resistive silicene-like thin flakes and Si nanostructures on graphene
Authors: Yue Naili , Myers Joshua , Su Liqin , Wang Wentao , Liu Fude , Tsu Raphael , Zhuang Yan , Zhang Yong
Published: June 2019

We report the growth of Si nanostructures, either as thin films or nanoparticles, on graphene substrates. The Si nanostructures are shown to be single crystalline, air stable and oxidation resistive, as indicated by the observation of a single crystalline Si Raman mode at around 520 cm–1, a STM image of an ordered surface structure under ambient condition, and a Schottky junction with graphite. Ultra-thin silicon regions exhibit silicene-like behavior, including a Raman mode at around 550 cm–1, a triangular lattice structure in STM that has distinctly different lattice spacing from that of either graphene or thicker Si, and metallic conductivity of up to 500 times higher than that of graphite. This work suggests a bottom-up approach to forming a Si nanostructure array on a large-scale patterned graphene substrate that can be used to fabricate nanoscale Si electronic devices.
The relativistic implicit Particle-in-Cell method
Authors: Bacchini Fabio , Amaya Jorge , Lapenta Giovanni
Published: June 2019

Relativistic Particle-in-Cell (PiC) methods are among the most reliable methods for the investigation of plasma phenomena at the particle scale. Standard explicit and semi-implicit PiC methods are affected by numerical instabilities that restrain the range of admissible simulation parameters, and prevent their application to large domains over long time scales. Here, we present a three-dimensional, fully-implicit algorithm for relativistic PiC simulations that conserves energy exactly (to machine precision) and eliminates numerical instabilities, allowing long-term calculations. We describe the full numerical solution procedure and test the algorithm with several one-and two-dimensional case-studies of kinetic instabilities, comparing the results with theoretical predictions.
Conservation of Gravitational Energy
Authors: Hanawa Tomoyuki
Published: June 2019

The total energy of an astronomical system is of great interest since the evolution of the system depends on it. Hence we solve the hydrodynamical equations by taking account of the conservation in numerical simulations of astrophysical objects. However, gravitational energy is often taken into account as a source term, and the total energy including gravity is not guaranteed to be conserved. This is partly because it increases the computational cost to solve hydrodynamical equations in the fully conservative form, i.e., those without any source term. This paper shows that the total energy and momentum of a system are fully conserved if the source terms due to gravity are properly taken into account. The error in the total energy is reduced as small as the round-off error. The method is applicable both when the gravitational force is given by the Poisson equation or explicitly as a function. The former case is confirmed by numerical simulations of 2D fragmentation of a self-gravitating gas. This method is applicable not only to the Cartesian uniform grid but an octree grid often used in adaptive mesh refinement.
Simulating 3-D Stellar Hydrodynamics using PPM and PPB Multifluid Gas Dynamics on CPU and CPU+GPU Nodes
Authors: Woodward Paul R. , Lin Pei-Hung , Mao Huaqing , Andrassy Robert , Herwig Falk
Published: June 2019

The special computational challenges of simulating 3-D hydrodynamics in deep stellar interiors are discussed, and numerical algorithmic responses described. Results of recent simulations carried out at scale on the NSF’s Blue Waters machine at the University of Illinois are presented, with a special focus on the computational challenges they address. Prospects for future work using GPU-accelerated nodes such as those on the DoE’s new Summit machine at Oak Ridge National Laboratory are described, with a focus on numerical algorithmic accommodations that we believe will be necessary.
Challenges and improvements in applying a particle image velocimetry (PIV) approach to granular flows
Authors: Sarno Luca , Tai Yih-Chin , Carravetta Armando , Martino Riccardo , Nicolina Papa Maria , Kuo Chih-Yu
Published: June 2019

The particle image velocimetry (PIV) is a well-established non-invasive optical technique for measuring the velocity field in fluids. Recently, the PIV approach has been extended to granular flows, where the medium under investigation is composed of a discrete number of grains that are typically non-transparent and of super-millimetric size. Granular PIV (g-PIV) still represents a non-standard application, as some accuracy concerns arise. In particular, since granular flows can be highly sheared, the choice of appropriate interrogation windows for the PIV analysis is not trivial. As well, owing to the spatially-averaged nature of the PIV approach, the estimation of second-order statistics remains a very challenging task. Here, we report a laboratory investigation on dry granular flows composed of glass spheres in a rotating drum. The velocity measurements at the sidewall are obtained by using a window deformation multi-pass PIV approach, where the open-source code PIVlab has been specifically used. Different combinations of the number of PIV passes and of interrogation windows are investigated. A slightly modified version of PIVlab allowed us to carry out g-PIV calculations with an arbitrary number of passes (i.e. greater than 4). Comparisons among different analyses helped us to identify reliable settings for g-PIV applications.