bluuebunny/crossref_metadata_2025 huggingface dataset:
Deployment of electric vehicle charging infrastructure. Application to the city of Madrid
Authors: DARCHERIF Alexandre , AMGHAR Bilal , DOUFENE Abdelkrim , JAAFARI Alain
Published: February 2020

Most of the scientific and economic observers expect electric vehicles (EVs) to reach more than one-third of new vehicle sales, by 2022 [1]. This growth will be even more pronounced in 2040, when it’s expected that more than 40 million of electric vehicles will be sold each year worldwide, leading to a considerable need for electrical energy (the equivalent of the production of about twenty nuclear power plants). This growth cannot be ensured if we do not radically transform our power supply technologies (new generations of batteries, new engines, new supply strategies, etc.) especially since the principal materials for batteries are projected to disappear in the next thirty years. Fortunately, new technologies for charging EVs are appearing (fast charging stations, inductive charging stations), which could help to reducing the need for larger batteries. However, these technologies require significant investment and heavy urban redevelopment. It is therefore important to find a way to optimize these investments both economically and technologically. In this paper, we will focus on electric vehicles and propose a model to optimize the urban infrastructure planning of energy supply stations. we have developed a new approach of infrastructure optimization based on battery charging platform existing technologies and their location in a city. A decision support tool applied to territorial planning is developed in this study.
Numerical and experimental investigation on the thermal behaviour of the building integrating occupant thermal comfort
Authors: Hawila Abed Al Waheed , Merabtine Abdelatif , Troussier Nadège
Published: February 2020

Simulation tools are widely used to model buildings in order to predict their indoor air quality and energy consumption. The prediction capability of the model is an influential factor in determining the ability of the building to be energy efficient and thermally comfortable. Thus, the validation of the developed models is crucial. In this context, this paper presents a numerical model developed using an object-oriented modelling tool based on the Modelica approach and a case study validation of this model. Then the thermal behaviour of the building and the occupants’ thermal comfort in the considered case study are investigated. The objective is to validate the developed model firstly by comparing predicted results with measured data regarding room temperature and relative humidity, and secondly by comparing the calculated thermal comfort indices (PMV and PPD) based on predicted results and measured data. The results show good agreement between simulations and experiments, with a maximum error in room temperature and relative humidity of 1.7 °C and 4.5%, respectively, and only 1% and 1.5% difference between averaged values of PMV and PPD, respectively.
Three-dimensional numerical study of mixed convection within a ventilated cavity (Shape ‘ L ‘) crossed by a nanofluid under the effect of a magnetic field
Authors: KHERROUBI S. , RAGUI K. , LABSI N. , BENKAHLA Y.K. , BOUTRA A.
Published: February 2020

The present work is dedicated to the three-dimensional numerical study of mixed convection heat transfer, taking place within a ventilated cavity (of shape L) crossed by Cu-water nanofluid. The enclosure is subjected to the action of a magnetic field. The ventilation is assured by two openings of the same size. The cold flow enters by an opening practiced at the top of the left wall, and exits by another opening practiced at the bottom of the right vertical wall. All the cavity walls are maintained at the same temperature, superior to that of the entering flow, except the side walls which are considered as adiabatic. The control parameters are: the Reynolds number and the Hartmann number as well as the nanoparticles volume fraction.
Mechanical and thermal characterization of compact blocks made of clayey earth with wood ashes addition
Authors: Milohin Gbénondé Sèna Gladys , Gbaguidi Sènouhoua Victor , Donnot André , Anjorin Malahimi , Benelmir Riad
Published: February 2020

The objective of this study is to evaluate the influence of wood ashes on the mechanical and thermal characteristics of the clayey earth-ashes compound (CEAC) compressed blocks. Variable mass percentages of 0% to 60% of wood ashes were incorporated to clayey earth stabilized with 10% of cement. The physical characteristics of the clayey earth were determined according to the protocols of the french association of normalization. The manufactured blocks were subjected to mechanical tests: simple compression and tensile by bending. The thermal conductivity was then appreciated by the method of the hot strip. The blocks made with a mixture of “90% clayey earth” and “10% cement”, usually used in construction in Benin, served as a reference material. From the results obtained, it appears that the clayey earth used is a soil A2ts: fine clayed sand in a very dry state. The results of the mechanical and thermal tests show that for an addition of wood ashes between 10% and 20% by weight, the performances of the blocks are significantly improved. The CEAC blocks formulated from 80% of the mixture “90% of clayey earth and 10% of cement” and 20% of wood ashes can be used as building materials.
Computational modelling of TRIANGULAR sub-boundary-layer vortex generators
Authors: Fernandez-Gamiz Unai , Ruiz de Loizaga Jon , Errasti Iñigo , Boyano Ana , Zulueta Ekaitz , Lopez-Guede Jose Manuel
Published: February 2020

Vortex generators (VGs) are used increasingly more by the wind turbine manufacture industry as flow control devices to improve rotor blade aerodynamic performance. The VG height is usually designed with equal thickness of the local boundary layer at the VG position. Nevertheless, these conventional VGs may produce excess residual drag in some applications. The so-called sub boundary layer VGs can provide enough momentum transfer over a region several times their own height for effective flow-separation control with much lower drag. The main objective is to investigate how well the simulations can reproduce the physics of the flow of the primary vortex generated by a triangular VG mounted on a flat plate with negligible pressure gradient with the angle of attack of the vane to the oncoming flow β= 18. Three different device heights H= 5mm, H1= 6,25mm, H2= 4,16mm have been studied and compared both qualitatively and quantitatively. To that end, computational simulations have been carried out using RANS method and at Reynolds number Re = 2600 based on the boundary layer momentum thickness θ= 2.4 mm at the VG position. The computational results show good agreement with the experimental data available in AVATAR project.
Incontinentia pigmenti – eine seltene Differenzialdiagnose bei Neugeborenen
Authors: von Dücker L. , Anemüller W.
Published: February 2020

Ein neugeborenes Mädchen afghanischer Eltern wurde noch am Tag der Geburt mit der Verdachtsdiagnose einer kongenitalen Herpesinfektion in die Kinderklinik überwiesen. Das ansonsten gesunde Kind wies bereits bei Geburt schuppende und vesikulöse Hautveränderungen auf. Die Eltern waren Cousine und Cousin und hatten noch 3 gesunde Töchter und 2 gesunde Söhne. Im Verlauf der nächsten Tage zeigten sich bei dem Neugeborenen Papeln und lineare Hyperpigmentierungen. Das histologische Bild zeigte eine eosinophile Spongiose. In der Gesamtschau kamen wir zur Diagnose einer Incontinentia pigmenti. Bei erneuter Befragung berichtete die Mutter von 2 Aborten mit männlichen Feten. Bei der körperlichen Untersuchung der gesamten Familie fielen bei der Mutter hypopigmentierte, striäre Flecken und Plaques an den Unterschenkeln auf, typisch für das späte Stadium einer Incontinentia pigmenti.
Pflegerische Nachsorge in der Alterspsychiatrie
Authors: Göhring Achim , Finsterle Karin , Boßler Barbara
Published: February 2020

Wenn ältere Patienten aus der Psychiatrie entlassen werden, sind sie und ihre Angehörigen oft auf sich allein gestellt. Um die Versorgungssituation zu Hause sicher zu gestalten und Versorgungsbrüche zu vermeiden, wurde am Zentrum für Psychiatrie Südwürttemberg das Projekt „Pflegerische Nachsorge in der Alterspsychiatrie“ gestartet.
Aktuelle Forschungsbemühungen zur Neuroprotektion, Verlauf und Behandlung eines Glaukoms
Authors: Jacobi Anne , van Zyl Tavé
Published: February 2020

Das Glaukom ist eine neurodegenerative Erkrankung, die mit der Zeit zu irreversibler Erblindung führt. Als bestimmendes Merkmal hier gilt der Verlust von retinalen Ganglienzellen (RGZ) im Auge und ihrer Axone im Sehnerv. Ein erhöhter Augeninnendruck (intraokularer Druck, IOD) gilt als Hauptrisikofaktor für die Entstehung eines Glaukoms, jedoch zeigt sich, dass dieser weder notwendig noch ausreichend für die Entstehung und das Fortschreiten der Erkrankung ist. Dies hat die Forschung und Entwicklung neuer Strategien zur Erkennung und Behandlung von Glaukomen mit dem Schwerpunkt auf Neuroprotektion – dem Schutz von RGZs vor dem Sterben – motiviert. Zusätzlich ist es im Bereich der Diagnose und Behandlung durch eine Reduktion des IOD in den letzten Jahren zur Entwicklung neuer Herangehensweisen gekommen. Dieser Artikel gibt einen Überblick über die zurzeit gängigen Theorien der pathophysiologischen Mechanismen, die einer Entstehung eines Glaukoms zugrunde liegen, sowie neuester Forschungsbemühungen mit Fokus auf Neuroprotektion und aktueller präklinischer und klinischer Studien, um eine Diagnose und Therapie des Glaukoms zu verbessern.
Neuroprotektion und Regeneration im Zentralnervensystem
Authors: Höltje Markus , Boato Francesco
Published: February 2020

Die Entwicklung neuroprotektiver und regenerativer Therapieansätze im Zentralnervensystem (ZNS) stellt eine große Herausforderung in der klinischen und grundlagenbasierten Forschung dar. Im Gegensatz zum peripheren Nervensystem, das eine vergleichsweise hohe intrinsische Regenerationsfähigkeit zeigt, ist diese Eigenschaft im adulten ZNS nur schwach ausgeprägt. In dieser Übersichtsarbeit sollen einige grundlegende Wachstumsmechanismen zentralnervöser Neurone beleuchtet werden, ebenso wie Faktoren, die einer erfolgreichen Regeneration nach Schädigung entgegenstehen. Vorwiegend im Kontext der Glaukomerkrankung werden präklinische und klinische Studien vorgestellt, die das Verständnis neurodegenerativer Vorgänge im optischen System verbessern und somit die Grundlagen für aktuelle und zukünftige Therapiestrategien liefern können.
A Questionnaire-Based Survey to Assess the Knowledge and Awareness of Denture Staining in Complete Denture Wearers
Authors: Cooper Pervez , Hegde Rakshith , Hegde Chethan
Published: February 2020

Background Knowledge of denture hygiene and staining is of importance for the edentulous patient to maintain a clean and hygienic prosthesis. However, many patients lack this basic knowledge. This survey aims at assessing the level of awareness among patients for the same.

Objective The aim and objective of this article are (1) to assess the knowledge of denture wearers on denture hygiene and maintenance, and (2) to gauge the awareness of denture wearers on denture staining.

Sample Selection Study sample will be consisting of 100 completely edentulous patients reporting to the Department of Prosthodontics in A. B. Shetty Memorial Institute of Dental Sciences.

Results Majority of the patients lacked proper education with regards to complete denture staining and hygiene maintenance and also lacked the proper motivation to carry out denture hygiene maintenance practices on a daily basis.
Factors Influencing Hearing Aid Adoption
Authors: Jorgensen Lindsey , Novak Michelle
Published: February 2020

In the field of audiology, change is inevitable: changes in technologies with hearing devices, changes in consumer knowledge, and changes in consumer-driven solutions. With these changes, the audiologist must adapt to meet the needs of the consumer. There are potential predictors that the audiologist could use to determine who is more likely to pursue and use amplification; by using these data, the audiologists may increase their productivity and increase patient satisfaction. The goal of this article is to investigate the MarkeTrak 10 (MT10) data to determine the trends in adoption and use of hearing aids as well as examine predictive factors that can be used to determine hearing aid adoption.
MarkeTrak 10 (MT10) Survey Results Demonstrate High Satisfaction with and Benefits from Hearing Aids
Authors: Picou Erin M.
Published: February 2020

The purpose of this article is threefold. First, it is to evaluate current rates of hearing aid satisfaction, in addition to the examination of factors that influence satisfaction rates. A second purpose is to evaluate the effects of hearing aid use on mental health and quality of life, from the consumer perspective. The third purpose of this article is to review the current status of the market in terms of usage and ownership. The usage statistics from MarkeTrak 10 answer questions such as what is the most common type of hearing aid style. And what types of hearing aid features are popular? The results of the usage statistics provide not only insight into the satisfaction and quality-of-life metrics but also information about marketplace trends. By fulfilling these purposes, strengths and weaknesses of the current hearing aid marketplace can be determined, guiding future technological and clinical practice developments. Survey results demonstrate the continued dominance of mini-BTE (behind the ear) hearing aids and high popularity of features, including wireless capabilities. Overall satisfaction rates are encouragingly high, driven by satisfaction with BTE instruments, especially those acquired in the past 5 years. Noted areas for improvement continue to be related to listening in noise and patient understanding of their hearing aids. Given the high levels of noted satisfaction, it is not surprising that the sample revealed significant hearing aid benefits, notably in a lower risk for depression, higher satisfaction listening in almost all environments, and improved quality of life on a regular basis. Together, these data provide insights into the factors that drive satisfaction, encourage industrial and scientific advancements in the identified areas of weakness, and paint a bright picture of the hearing aid market from the consumer perspective.
Can we use linear response theory to assess geoengineering strategies?
Authors: Bódai Tamás , Lucarini Valerio , Lunkeit Frank
Published: February 2020

Geoengineering can control only some climatic variables but not others, resulting in side-effects. We investigate in an intermediate-complexity climate model the applicability of linear response theory (LRT) to the assessment of a geoengineering method. This application of LRT is twofold. First, our objective (O1) is to assess only the best possible geoengineering scenario by looking for a suitable modulation of solar forcing that can cancel out or otherwise modulate a climate change signal that would result from a rise in carbon dioxide concentration [CO2] alone. Here, we consider only the cancellation of the expected global mean surface air temperature Δ⟨[Ts]⟩. It is in fact a straightforward inverse problem for this solar forcing, and, considering an infinite time period, we use LRT to provide the solution in the frequency domain in closed form as fs(ω)=(Δ⟨[Ts]⟩(ω)−χg(ω)fg(ω))/χs(ω), where the χ’s are linear susceptibilities. We provide procedures suitable for numerical implementation that apply to finite time periods too. Second, to be able to utilize LRT to quantify side-effects, the response with respect to uncontrolled observables, such as regional averages ⟨Ts⟩, must be approximately linear. Therefore, our objective (O2) here is to assess the linearity of the response. We find that under geoengineering in the sense of (O1), i.e., under combined greenhouse and required solar forcing, the asymptotic response Δ⟨[Ts]⟩ is actually not zero. This turns out not to be due to nonlinearity of the response under geoengineering, but rather a consequence of inaccurate determination of the linear susceptibilities χ. The error is in fact due to a significant quadratic nonlinearity of the response under system identification achieved by a forced experiment. This nonlinear contribution can be easily removed, which results in much better estimates of the linear susceptibility, and, in turn, in a fivefold reduction in Δ⟨[Ts]⟩ under geoengineering practice. This correction dramatically improves also the agreement of the spatial patterns of the predicted linear and the true model responses. However, considering (O2), such an agreement is not perfect and is worse in the case of the precipitation patterns as opposed to surface temperature. Some evidence suggests that it could be due to a greater degree of nonlinearity in the case of precipitation.
Defects of Bénard cell on a propagating front
Authors: Wu Di , Duan Li , Kang Qi
Published: February 2020

Bénard-Marangoni convection can be used to self-organize hexagonal convective cells, but defects easily emerge in the hexagonal pattern, which hinders its application in industry. The dynamics of front propagation and defect generation are studied in this paper. We focus especially on the onset process of a local disturbance of a hexagonal pattern, named the “nucleus.” The front propagation of the nucleus has been researched through numerical simulations of a model equation and experiments. In the numerical simulations, a single nucleus can evolve into a perfect hexagon pattern under critical or subcritical conditions, and a random disturbance can generate multiple nuclei which evolve into grain boundaries. In addition, under supercritical conditions, defects also emerge as a single nucleus grows. The instability of front propagation is considered to be the mechanism for the generation of irregular patterns. The curvature effect makes the protrusion of the front have a larger velocity in supercriticality, which results in a wavy front, and defects are generated in the concave portion of the front. Also, because of the curvature effect, the front of an irregular pattern has a larger velocity than that of the regular pattern since the protrusion of the front in the irregular pattern increases the average velocity. Experiments have also been carried out by using an infrared camera to analyze front propagation. The results are qualitatively in agreement with the results of numerical simulations. Through the study of defect generation in front propagation, we put forward a method for generating a hexagon pattern which greatly reduces the number of defects.
Charge breeding at GANIL: Improvements, results, and comparison with the other facilities
Authors: Maunoury Laurent , Dubois Mickael , Delahaye Pierre , Annaluru Arun , Bajeat Olivier , Frigot Romain , Hormigos Stéphane , Jacquot Bertrand , Jardin Pascal , Osmond Benoit , Predrag Ujic , Retailleau Blaise-Mael , Savalle Alain , Toivanen Ville , Thomas Jean-Charles , Angot Julien , Sole Patrick , Lamy Thierry , Koivisto Hannu , Marttinen Miha , Tarvainen Olli
Published: February 2020

The 1+/n+ method, based on an ECRIS charge breeder (CB) originally developed at the LPSC laboratory, is now implemented at GANIL for the production of Radioactive Ion Beams (RIBs). Prior to its installation in the middle of the low energy beam line of the SPIRAL1 facility, the 1+/n+ system CB has been modified based on the experiments performed on the CARIBU Facility at Argone National Laboratory. Later, it has been tested at the 1+/n+ LPSC test bench to validate its operation performances. Charge breeding efficiencies as well as charge breeding times have been measured for noble gases and alkali elements. The commissioning phase started at GANIL in the second half-year of 2017. It consisted of a stepwise process to test the upgrade of the SPIRAL1 facility from simple validation [operation of Charge Breeder (CB) as a stand-alone source] up to the production of the first 1+/n+ RIB. Thus, this year, a 38mK/38K RIB has been successfully delivered to a physics experiment over a period of 1 week. The yields on the physics target were in the range of ∼2–4 × 106 pps at 9 MeV/u. The target ion source system (TISS) was made of a FEBIAD ion source connected to a hot graphite target. This is the first time a RIB is accelerated with a cyclotron with the 1+/n+ method. Moreover, a production test with the FEBIAD TISS has confirmed the yields measured previously, which validates the extension of the GANIL/SPIRAL1 catalog for a number of isotopes. In parallel, R&D is being performed on new TISSs (e.g., a fast release one, using surface ionization source). Targets are also a subject of ongoing R&D for yield and release time optimization. This contribution will present the new acceleration scheme of the SPIRAL1 facility, which largely extends the palette of RIBs available for nuclear physicists. It will be compared to the ones used at similar ISOL facilities. This facility is more than a simple ISOL facility, and an overview of the new opportunities offered by the upgraded installation will be also discussed.
Energy-tunable photon-enhanced thermal tunneling electrons for intrinsic adaptive full spectrum solar energy conversion
Authors: Chen Yicong , Deng Shaozhi , Xu Ningsheng , Chen Jun
Published: February 2020

Considering that the actual terrestrial solar irradiance is dynamically changing with the atmosphere, the overall efficiencies of most current solar cells are much lower than the reported static values that are based on a standard solar spectrum. The realizations of solar cells, which can maintain high efficiency under variable solar irradiance, are necessary for further improvement of solar energy conversion. In this work, a metal-insulator-semiconductor (MIS) structure based photon-enhanced thermionic energy converter (PETEC) has been proposed for intrinsic adaptive full spectrum solar energy conversion. The basic idea is to form the thermionic electron with desired energy by the photon-enhanced thermal tunneling process. Investigations on its fundamental performance indicate that the MIS-PETEC can have an overall output energy improvement of at least 0.8%, 2.5%, and 3% in typical sunny, rainy, and cloudy days compared to the normal PETEC. Additionally, the total output energy over a year can be improved by at least 3%. These results offer an alternate technique for intrinsic adaptive full spectrum solar energy conversion, which is helpful for the development of next generation high performance solar cells.
A polymer film with ultra-broadband optical gain characteristics
Authors: Hara Yuya , Higase Youtaro , Taguchi Marie , Takahashi Shun , Sasaki Fumio , Yamashita Kenichi
Published: February 2020

Miniaturization of the tunable laser equipment is an important factor for further development in various optoelectronic technologies. To realize the compact tunable laser devices, an optical gain medium having a broadband optical gain characteristic is required. In this study, we propose a promising strategy for preparing an optical gain film that exhibits a ∼250 nm gain bandwidth in the visible wavelength region. This film consists of a polymer matrix co-doped with organic luminescent molecules that form a complex of the excited state, i.e., exciplex. The exciplex state can co-exist with the monomolecular exciton state, leading to broadband (400–650 nm) optical gain with a large Stokes shift. Optically pumped lasing action is also possible when the film is combined with an optical resonator. This strategy would be useful for developing a compact tunable laser device without active medium replacement.
Element-specific spin and orbital moments and perpendicular magnetic anisotropy in Ta/CoFeB/MgO structures
Authors: Yan Yu , Lu Xianyang , Liu Bo , Zhang Xiaoqian , Zheng Xiangyu , Meng Hao , Liu Wenqing , Wang Junlin , Will Iain G. , Wu Jing , Wong Ping Kwan Johnny , Cai Jianwang , Du Jun , Zhang Rong , Xu Yongbing
Published: February 2020

Perpendicular magnetic anisotropy (PMA) in the Ta/CoFeB/MgO system has been studied using x-ray magnetic circular dichroism and vibrating sample magnetometry. The ratios of the orbital to spin magnetic moments of Co atoms in the Ta/CoFeB/MgO structures with PMA have been found to be enhanced by 100%, compared with the Ta/CoFeB/Ta structure without PMA. The orbital moments of Co are as large as 0.30μB, more than half of their spin moments in the perpendicularly magnetized Ta/CoFeB/MgO structures. The results indicate that the PMA observed in the CoFeB/MgO structures is related to the increased spin–orbital coupling of the Co atoms. This work offers experimental evidence of the correlation between PMA and the element-specific spin and orbital moments in the Ta/CoFeB/MgO systems.
The formation process and structure of the skyrmion bubble lattice in magnetic multilayers
Authors: Wang Y. , Cao J. W. , Liu Q. F.
Published: February 2020

Magnetic skyrmions are attracting considerable interest in scientific research and practical applications. Recently, a novel phenomenon was observed in which a skyrmion bubble lattice could be induced by a slightly tilted in-plane magnetic field in a multilayer film. In this article, the formation process of a skyrmion bubble lattice was investigated by micromagnetic simulation considering the Dzyaloshinskii–Moriya (DM) interaction and distribution of magnetic anisotropy. The exchange field that prevents the reversal of moments was minimized when the magnetic moments were aligned by a slightly tilted in-plane magnetic field. Many small reversed domains were formed in the regions where the demagnetization field conquers the anisotropy field after the removal of the external field and developed into a stable skyrmion bubble array. The DM interaction has an obvious influence on the size and precise moment structure of the stable skyrmion bubbles but has little effect on the nucleation of reversed domains.
Pb dimerization greatly accelerates charge losses in MAPbI3: Time-domain ab initio analysis
Authors: Zhang Zhaosheng , Qiao Lu , Mora-Perez Carlos , Long Run , Prezhdo Oleg V.
Published: February 2020

Metal halide perovskites constitute a new type of semiconducting materials with long charge carrier lifetimes and efficient light-harvesting. The performance of perovskite solar cells and related devices is limited by nonradiative charge and energy losses, facilitated by defects. Combining nonadiabatic molecular dynamics and time-domain density functional theory, we demonstrate that charge losses depend strongly on the defect chemical state. By considering an extra Pb atom in CH3NH3PbI3, which is a common defect in lead halide perovskites, we investigate its influence on charge trapping and recombination. In a chemically inert form as a Pb interstitial, the extra Pb atom has only a mild influence on charge recombination. However, if the extra Pb atom binds to a native Pb atom to form a dimer, the charge trapping and recombination are greatly accelerated because the Pb-dimer creates a localized midgap trap state that couples strongly to the perovskite valence band edge. Holes disappear from the valence band two orders of magnitude faster than in the pristine perovskite and recombine with conduction band electrons one order of magnitude faster. The simulations identify the phonon modes involved in the nonradiative charge trapping and recombination and highlight the importance of rapid decoherence within the electronic subsystem for long carrier lifetimes. The detailed atomistic analysis of the charge trapping and recombination mechanisms enriches the understanding of defect properties and provides theoretical guidance for improving perovskite performance.
High-throughput electrochemical sensing platform for screening nanomaterial–biomembrane interactions
Authors: Owen Joshua , Kuznecovs Maksims , Bhamji Raeesa , William Nicola , Domenech-Garcia Natalia , Hesler Michelle , Knoll Thorsten , Kohl Yvonne , Nelson Andrew , Kapur Nikil
Published: February 2020

A high-throughput, automated screening platform has been developed for the assessment of biological membrane damage caused by nanomaterials. Membrane damage is detected using the technique of analyzing capacitance–current peak changes obtained through rapid cyclic voltammetry measurements of a phospholipid self-assembled monolayer formed on a mercury film deposited onto a microfabricated platinum electrode after the interaction of a biomembrane-active species. To significantly improve wider usability of the screening technique, a compact, high-throughput screening platform was designed, integrating the monolayer-supporting microfabricated electrode into a microfluidic flow cell, with bespoke pumps used for precise, automated control of fluid flow. Chlorpromazine, a tricyclic antidepressant, and a citrate-coated 50 nm diameter gold nanomaterial (AuNM) were screened to successfully demonstrate the platform’s viability for high-throughput screening. Chlorpromazine and the AuNM showed interactions with a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) monolayer at concentrations in excess of 1 µmol dm−3. Biological validity of the electrochemically measured interaction of chlorpromazine with DOPC monolayers was confirmed through quantitative comparisons with HepG2 and A549 cytotoxicity assays. The platform also demonstrated desirable performance for high-throughput screening, with membrane interactions detected in <6 min per assay. Automation contributed to this significantly by reducing the required operating skill level when using the technique and minimizing fluid consumption.
Large memcapacitance and memristance at Nb:SrTiO3/La0.5Sr0.5Mn0.5Co0.5O3-δ topotactic redox interface
Authors: Román Acevedo W. , van den Bosch C. A. M. , Aguirre M. H. , Acha C. , Cavallaro A. , Ferreyra C. , Sánchez M. J. , Patrone L. , Aguadero A. , Rubi D.
Published: February 2020

The possibility to develop neuromorphic computing devices able to mimic the extraordinary data processing capabilities of biological systems spurs the research on memristive systems. Memristors with additional functionalities such as robust memcapacitance can outperform standard devices in key aspects such as power consumption or miniaturization possibilities. In this work, we demonstrate a large memcapacitive response of a perovskite memristive interface, using the topotactic redox ability of La0.5Sr0.5Mn0.5Co0.5O3-δ (LSMCO, 0 ≤ δ ≤ 0.62). We demonstrate that the multi-mem behavior originates at the switchable n-p diode formed at the Nb:SrTiO3/LSMCO interface. We found for our Nb:SrTiO3/LSMCO/Pt devices a memcapacitive effect CHIGH/CLOW ∼ 100 at 150 kHz. The proof-of-concept interface reported here opens a promising venue to use topotactic redox materials for disruptive nanoelectronics, with straightforward applications in neuromorphic computing technology.
Performance improvement of organic resistive memories by exploiting synergistic layered nanohybrid dispersed polymer composites
Authors: Gogoi Koustav Kashyap , Chowdhury Avijit
Published: February 2020

Functionalized layered nanohybrid materials have been thoroughly explored in numerous practical applications including photocatalysis, supercapacitors, and sensors, and have inherent potential to excel in the field of organic resistive random access memory devices as well. Herein, we report an efficient, facile, and cost-effective in situ synthesis route to prepare a layered nanohybrid by grafting cadmium sulfide (CdS) nanorods with exfoliated graphene oxide (GOs) sheets via the one-step hydrothermal functionalization technique. Such a nanohybrid material displays advantageous characteristics possessed by them due to the formation of organic–inorganic heterojunctions at their interface. Sandwiched devices, with a configuration of ITO/reduced graphene oxide–CdS/poly-methyl methacrylate (PMMA)/Al, are fabricated by dispersing different wt. % of the layered nanohybrid in a poly-methyl methacrylate (PMMA) matrix. Detailed current density vs voltage (J–V) studies exhibit excellent bipolar resistive switching characteristics reaching a very low set voltage of ∼−0.48V, high current ION/IOFF ratios of ∼106, and ultralow set/reset power densities of ∼10−8/10−6W/cm2 for devices containing 0.4 wt. % nanohybrid nanofillers. Partial reduction of GOs and the formation of heterojunctions during the synthesis process undoubtedly boost the resistive memory performances resulting from the synergistic effect in layered nanohybrid materials. The fabricated devices have been subjected to various analyses in order to test their stability, repeatability, and reliability, all of which have been found to display encouraging results.
Insights into the π – π interaction driven non-covalent functionalization of carbon nanotubes of various diameters by conjugated fluorene and carbazole copolymers
Authors: Benda Robert , Zucchi Gaël , Cancès Eric , Lebental Bérengère
Published: February 2020

We investigate the interaction of polyfluorene and fluorene/carbazole copolymers bearing various functional groups and side chains with small to large diameter—from 1.7 nm to 9 nm—carbon nanotubes (CNTs) in vacuo. We use variable-charge molecular dynamics simulations based on the reactive force field ReaxFF. We show that non-covalent functionalization of nanotubes, driven by π − π interactions, is effective for all the polymers studied, thanks to their conjugated backbone and regardless of the presence of specific functional groups. The geometry at equilibrium of these polymer/CNT hybrids is analyzed in detail at the scale of each fluorene or carbazole unit. The role of both the functional groups and the alkyl chain length is analyzed in detail. Adsorption of the polymers on the nanotube sidewalls is shown to be either complete—with the whole chain physisorbed—or partial—due to intrachain coiling or interchain repulsion—depending on the initial geometry, number of polymers, and nanotube diameter. Energetic arguments supplement the described geometric features. Both energetic and geometric adsorption features are derived here for the first time for large diameter carbon nanotubes (up to 9 nm) and fluorene/carbazole copolymers having up to 30 monomers and bearing different functional groups. The force field ReaxFF and its available parameterization used for the simulations are validated, thanks to a benchmark and review on higher-level quantum calculations—for simple π − π interacting compounds made up of polycyclic aromatic molecules adsorbed on a graphene sheet or bilayer graphene. Although it is shown that the influence of the nanotube chirality on the adsorption pattern and binding strength cannot be discussed with our method, we highlight that an available force field such as ReaxFF and its parameterization can be transferable to simulate new systems without specific re-parameterization, provided that this model is validated against reference methods or data. This methodology proves to be a valuable tool for optimal polymer design for nanotube functionalization at no re-parameterization cost and could be adapted to simulate and assist the design of other types of molecular systems.
Hydrodynamic behavior of two-dimensional tandem-arranged flapping flexible foils in uniform flow
Authors: Cong Longfei , Teng Bin , Cheng Liang
Published: February 2020

Hydrodynamic behavior of two-dimensional tandem-arranged flapping flexible foils in uniform flow is investigated numerically by an immersed boundary-lattice Boltzmann method. The leading edge of the leading foil is forced to undergo both heave and pitch motions, while the leading edge of the trailing foil is forced to undergo heave motion only. Of particular interests are the effects of stream-wise gap distance Gx (Gx/c = 0.25–1.75, where c denotes the length of the foil) and the phase difference Φ between the heave motions of the foils (Φ/π = −1.00 to 1.00) on the hydrodynamic characteristics of the foils, such as the propulsive force, the propulsive efficiency, the passive deformation, and the flow field around the foils. For the leading foil, because of the existence of the trailing foil and the resulting gap flow between the foils, the propulsive performance is noticeably influenced by Φ at small Gx/c values and such an influence is weakened with increasing Gx/c. For the trailing foil, the propulsive performance is primarily affected by Φ, and the physics behind such a strong effect is that Φ dictates the manner by which the vortices shed from the leading foil interact with the trailing foil. In contrast, the interaction of the vortices shed from the leading foil with the trailing foil is not significantly affected by Gx/c because the trailing foil experiences similar vortices shed from the leading foil, regardless of Gx/c. With different Gx/c and Φ/π values, three distinct deformation states of the foils, namely, the symmetric periodic state, the asymmetric periodic state, and the irregular state, are identified and are mapped out in the (Φ/π, Gx/c) space. Good correlation between the deformation state of the foils and the propulsive performance of the trailing foil has been observed.
Metal adsorbate interactions and the convergence of density functional calculations
Authors: Rohmann Christoph , Ochoa Maicol A. , Zwolak Michael
Published: February 2020

The adsorption of metal atoms on nanostructures, such as graphene and nanotubes, plays an important role in catalysis, electronic doping, and tuning material properties. Quantum chemical calculations permit the investigation of this process to discover desirable interactions and obtain mechanistic insights into adsorbate behavior, of which the binding strength is a central quantity. Binding strengths, however, vary widely in the literature, even when using almost identical computational methods. To address this issue, we investigate the adsorption of a variety of metals onto graphene, carbon nanotubes, and boron nitride nanotubes. As is well-known, calculations on periodic structures require a sufficiently large system size to remove interactions between periodic images. Our results indicate that there are both direct and indirect mechanisms for this interaction, where the latter can require even larger system sizes than typically employed. The magnitude and distance of the effect depends on the electronic state of the substrate and the open- or closed-shell nature of the adsorbate. For instance, insulating substrates (e.g., boron nitride nanotubes) show essentially no dependence on system size, whereas metallic or semi-metallic systems can have a substantial effect due to the delocalized nature of the electronic states interacting with the adsorbate. We derive a scaling relation for the length dependence with a representative tight-binding model. These results demonstrate how to extrapolate the binding energies to the isolated-impurity limit.
Microplasma emission spectroscopy of carbon dioxide using the carbon monoxide Ångström system
Authors: Persson Anders , Berglund Martin
Published: February 2020

The present paper describes a system and method for indirect emission spectroscopy of CO2 in the visible spectrum. This is achieved by using a microplasma spectrometer that first converts CO2 into CO and then measures emissions from the CO Ångström system (B1Σ + → A1Π) at 560 nm. The experiments were performed on gaseous samples of CO2, mixed in both N2 and air, to concentrations between 0.01% and 100%. In addition to the microplasma spectrometer, the process was monitored by mass spectrometry with a residual gas analyzer. The CO2 to CO conversion efficiency was found to be very high, reaching a maximum of 41% at close to 100% selectivity. Furthermore, the CO Ångström system was shown to facilitate excellent spectroscopic measurement of CO2 concentrations below 10%, with a linearity of R2 > 0.99 and an expected limit of detection in the parts-per-thousands range. The most promising aspect of the results was that the analysis was performed on extremely small total sample amounts where the gas flow through the systems was in the 0.1 µmole/s range. Hence, the present system has the prospect of filling a void in current sensor technology, where inexpensive and easy-to-use optical systems, such as nondispersive infrared sensors, cannot handle small sample amounts, while mass spectrometers, which can handle such samples, still are expensive, complex, and bulky.
Large piezoelectric coefficients combined with high electron mobilities in Janus monolayer XTeI (X = Sb and Bi): A first-principles study
Authors: Guo San-Dong , Guo Xiao-Shu , Liu Zhao-Yang , Quan Ying-Ni
Published: February 2020

The absence of both the inversion symmetry and out-of-plane mirror symmetry together with spin–orbit coupling (SOC) can induce novel electronic and piezoelectric properties. In this work, the piezoelectric properties along with carrier mobilities of Janus monolayer XTeI (X=Sb and Bi) are studied by density functional theory. By using generalized gradient approximation (GGA) plus SOC, they are found to be indirect gap semiconductors with the Rashba spin splitting. The piezoelectric tensors of Janus monolayer XTeI (X=Sb and Bi) are reported by using the density functional perturbation theory. Due to lacking both the inversion symmetry and out-of-plane mirror symmetry for Janus monolayer XTeI (X=Sb and Bi), both in-plane and out-of-plane piezoelectric effects can be observed, and the large piezoelectric coefficients are predicted (e.g., d11=12.95pm/V for SbTeI and d11=8.20pm/V for BiTeI), which are comparable and even higher than the ones of many other two-dimensional materials and other well-known bulk piezoelectric materials, especially for out-of-plane piezoelectric coefficients. With GGA+SOC, the high electron carrier mobilities are obtained, and the electron mobility of BiTeI along armchair direction reaches up to about 1319cm2V−1s−1. The carrier mobility shows a rather pronounced anisotropy between electron and hole/armchair and zigzag directions. It is found that tensile strain can improve the piezoelectric coefficients d11 of Janus monolayer XTeI (X=Sb and Bi). For example, at 4% strain, the d11 of SbTeI (BiTeI) is up to 20.12 pm/V (11.48 pm/V), compared with unstrained 12.95 pm/V (8.20 pm/V). Our works imply Janus monolayer XTeI (X=Sb and Bi) have potential applications in flexible electronics and piezoelectric devices, and can stimulate further experimental works.
Abnormally low thermal conductivity of 2D selenene: An ab initio study
Authors: Liu Gang , Gao Zhibin , Li Guo-Ling , Wang Hui
Published: February 2020

The lattice thermal conductivity and thermal transport properties of 2D α-selenene are investigated based on the first-principles calculations. The isotropic in-plane thermal conductivity is as low as 3.04 W m−1 K−1 at room temperature, even abnormally lower than α-tellurene that processes analogous configuration and lower Debye temperature. We find this abnormal phenomenon reasonably stems from the larger anharmonicity of the acoustic phonon branch. Moreover, the phonon spectra, elastic properties, and related thermal properties are also exhibited. Acoustic phonons contribute mainly to the total thermal conductivity. Furthermore, size effect, boundary effect, the total phase space for three-phonon processes, phonon group velocity, and relaxation time are further investigated, and the last one is unveiled to be the key ingredient of thermal transport in 2D selenene.
Thermal conductivity of two-dimensional disordered fibrous materials defined by interfiber thermal contact conductance and intrinsic conductivity of fibers
Authors: Volkov Alexey N. , Zhigilei Leonid V.
Published: February 2020

A general framework for the theoretical analysis and numerical calculations of the effective thermal conductivity of two-dimensional homogeneous and isotropic disordered fibrous materials is developed in this work based on the model of random contacts between soft-core spherocylinders. The analysis accounts for the interfiber contact conductance and intrinsic conductivity of fibers and is performed in a wide space of governing parameters that includes the fiber aspect ratio, Biot number calculated for a single thermal contact between fibers, and material density ranging from values corresponding to the percolation threshold up to those characteristic of dense fiber networks. For dense networks, exact theoretical equations for the thermal conductivity of materials composed of spherocylinders with an arbitrary aspect ratio and Biot number are derived. The effect of the intrinsic conductivity of fibers on the thermal transport in fibrous materials is found to depend on the density of contacts and can be significant in sufficiently dense fiber networks even if the Biot number for a single thermal contact is small. Semiempirical corrections to the theoretical equations are derived for small and moderate fiber densities. The power law exponent describing the approximate dependence of the conductivity on the density parameter is found to vary from values close to 1 up to values exceeding 2 when evaluated within different finite ranges of the density parameter. This finding explains the variability of scaling laws for thermal conductivity of fibrous materials suggested in the literature based on numerical simulations performed in different regions of the space of material parameters.
High performance supercapacitor electrodes based on spinel NiCo2O4@MWCNT composite with insights from density functional theory simulations
Authors: Pathak Mansi , Jose Jeena Rose , Chakraborty Brahmananda , Rout Chandra Sekhar
Published: February 2020

In this work, we demonstrated the supercapacitor performance of pristine and composites of spinel NiCo2O4 with a multi-walled carbon nanotube (MWCNT) assembled in a two-electrode cell configuration. Spinel NiCo2O4 and NiCo2O4@MWCNT composites were synthesized via a facile hydrothermal method. The supercapacitive performance of as-synthesized NiCo2O4 and NiCo2O4@MWCNT fabricated on Ni-foam was studied in a 0.5M K2SO4 electrolyte using electrochemical measurement techniques. The symmetric cell configuration of NiCo2O4@MWCNT delivers high specific capacitance (374 F/g at 2 A/g) with high energy density and power density (95 Wh/kg and 3 964 W/kg, respectively) compared to that of pristine NiCo2O4 electrodes (137 F/g at 0.6 A/g). Furthermore, the energy storage performance of the asymmetric cells of NiCo2O4//MWCNT and NiCo2O4@MWCNT//MWCNT was studied to enhance cycling stability (retention of 74.85% over 3000 cycles). We have also theoretically studied the supercapacitance performance of pristine NiCo2O4 and NiCo2O4@SWCNT hybrid structures through its structural and electronic properties using density functional theory predictions. The higher specific capacitance of the NiCo2O4@SWCNT hybrid system with high power density and energy density is supported by the enhanced density of states near the Fermi level and increased quantum capacitance of the hybrid structure. We have theoretically computed the diffusion energy barrier of K+ ions of the K2SO4 electrolyte in the NiCo2O4 layer and compared it with the diffusion barrier for Na+ ions. The lesser diffusion energy barrier for K+ ions in the NiCo2O4 layer contributes toward higher energy storage capacity. Thus, owing to superior electrochemical performance of NiCo2O4 composites with MWCNTs, it can serve as a high-performance electrode material for supercapacitor applications.
Developing a camera-based 3D momentum imaging system capable of 1 Mhits/s
Authors: Debrah Duke A. , Stewart Gabriel A. , Basnayake Gihan , Nomerotski Andrei , Svihra Peter , Lee Suk Kyoung , Li Wen
Published: February 2020

A camera-based three-dimensional (3D) imaging system with a superb time-of-flight (TOF) resolution and multi-hit capability was recently developed for electron/ion imaging [Lee et al. J. Chem. Phys. 141, 221101 (2014)]. In this work, we report further improvement of the event rate of the system by adopting an event-driven camera, Tpx3Cam, for detecting the 2D positions of electrons, while a high-speed digitizer provides highly accurate (∼30 ps) TOF information for each event at a rate approaching 1 Mhits/sec.