bluuebunny/crossref_metadata_2025 huggingface dataset:
Amorphous Si1−yCy composite anode materials: ab initio molecular dynamics for behaviors of Li and Na in the framework
Authors: Hur Jaewoong
Published: March 2021

Random configurations and formation energies of a-MxSi1−yCy frameworks at x = 3.0 of Li and x = 0.5 of Na contents.
Theoretical and experimental study of peroxy and alkoxy radicals in the NO3-initiated oxidation of isoprene
Authors: Vereecken L. , Carlsson P. T. M. , Novelli A. , Bernard F. , Brown S. S. , Cho C. , Crowley J. N. , Fuchs H. , Mellouki W. , Reimer D. , Shenolikar J. , Tillmann R. , Zhou L. , Kiendler-Scharr A. , Wahner A.
Published: March 2021

Under atmospheric conditions, nitrate-RO2 radicals are equilibrated and react predominantly with HO2, RO2 and NO. The nitrate-RO chemistry is affected strongly by ring closure to epoxy radicals, impeding formation of MVK/MACR.
The contribution of non-classical CHax⋯OC hydrogen bonds to the anomeric effect in fluoro and oxa-methoxycyclohexanes
Authors: Piscelli Bruno A. , O’Hagan David , Cormanich Rodrigo A.
Published: March 2021

In this theory study the dominance of non-classical 1,3-diaxial CHax⋯OC hydrogen bonds (NCHBs) dictating anomeric effects in fluorinated methoxycyclohexanes and 2-methoxytetrahydropyrans is demonstrated, a phenomenon which is most often described as a consequence of hyperconjugation.
Syngas to light olefin synthesis over La doped ZnxAlyOz composite and SAPO-34 hybrid catalysts
Authors: Raveendra G. , Ma Baorun , Liu Xiaohui , Guo Yong , Wang Yanqin
Published: March 2021

La doped ZnxAlyOz with SAPO-34 hybrid catalysts for syngas to light olefin synthesis showed higher CO conversion and light olefin selectivity.
Zinc/selenium conversion battery: a system highly compatible with both organic and aqueous electrolytes
Authors: Chen Ze , Mo Funian , Wang Tairan , Yang Qi , Huang Zhaodong , Wang Donghong , Liang Guojing , Chen Ao , Li Qing , Guo Ying , Li Xinliang , Fan Jun , Zhi Chunyi
Published: March 2021

Both organic and aqueous zinc–selenium batteries deliver competitive capacity with a higher plateau voltage than traditional zinc ion batteries.
Spontaneous interface engineering for dopant-free poly(3-hexylthiophene) perovskite solar cells with efficiency over 24%
Authors: Jeong Min Ju , Yeom Kyung Mun , Kim Se Jin , Jung Eui Hyuk , Noh Jun Hong
Published: March 2021

Halide perovskite solar cells (PSCs) have recently shown a leap forward in performance by reducing the recombination loss at the interface between the perovskite and hole-transporting layers through surface treatment.
Colonisation with endogenousLactobacillus reuteriR28 and exogenousLactobacillus plantarumAR17-1 and the effects on intestinal inflammation in mice
Authors: Wang Guangqiang , Chen Yan , Fei Su , Xie Chunliang , Xia Yongjun , Ai Lianzhong
Published: March 2021

Endogenous and exogenous strains exhibit no significant differences in healthy mice, whereas after PEG treatment, colonisation of endogenous strain is greatly enhanced.
Investigation of the catalytic activity and reaction kinetic modeling of two antimony catalysts in the synthesis of poly(ethylene furanoate)
Authors: Papadopoulos Lazaros , Zamboulis Alexandra , Kasmi Nejib , Wahbi Mohamed , Nannou Christina , Lambropoulou Dimitra A. , Kostoglou Margaritis , Papageorgiou George Z. , Bikiaris Dimitrios N.
Published: March 2021

The catalytic activity of two antimony catalysts was studied in the direct polymerization of 2,5-furandicarboxylic acid with ethylene glycol to afford poly(ethylene furanoate), a biobased polyester for packaging applications.
High carrier mobility and ultralow thermal conductivity in the synthetic layered superlattice Sn4Bi10Se19
Authors: Lu Ruiming , Olvera Alan , Bailey Trevor P. , Fu Jiefei , Su Xianli , Veremchuk Igor , Yin Zhixiong , Buchanan Brandon , Uher Ctirad , Tang Xinfeng , Grin Yuri , Poudeu Pierre F. P.
Published: March 2021

Phonon scattering from Bi2Se3/SnSe/Bi2Se3 interfaces and high carrier mobility within the 2D Bi2Se3-layer lead to the coexistence of ultralow lattice thermal conductivity and high electrical conductivity in the Sn4Bi10Se19 synthetic superlattice.
Non-volatile conductive gels made from deep eutectic solvents and oxidised cellulose nanofibrils
Authors: Bryant Saffron J. , da Silva Marcelo A. , Hossain Kazi M. Zakir , Calabrese Vincenzo , Scott Janet L. , Edler Karen J.
Published: March 2021

Conductive, shear-thinning gels made from deep eutectic solvents and cellulose nanofibrils.
Active colloids orbiting giant vesicles
Authors: Sharma Vaibhav , Azar Elise , Schroder Andre P. , Marques Carlos M. , Stocco Antonio
Published: March 2021

A self-propelled Janus colloid performs a persistent orbital motion around a giant unilamellar vesicle, even when the vesicle size is comparable to the particle size.
A new urinary exosome enrichment method by a combination of ultrafiltration and TiO2 nanoparticles
Authors: Xiang Xiaochao , Guan Fulin , Jiao Fenglong , Li Hang , Zhang Wanjun , Zhang Yangjun , Qin Weijie
Published: March 2021

The workflow of separation and enrichment of exosomes by ultrafiltration–TiO2. We proposed a new strategy for facile exosome isolation from human urine by utilizing the ultrafiltration technique and TiO2, which can significantly reduce urine volumes, increase exposure of the material to exosomes in urine and obtain high purity exosomes.
Rapid detection of free and bound toxins using molecularly imprinted silica/graphene oxide hybrids
Authors: Ruiz-Gonzalez Antonio , Clancy Adam J. , Choy Kwang-Leong
Published: March 2021

A miniaturised electrochemical sensor integrating a molecularly imprinted silica/graphene oxide hybrid with non-equilibrium pulse amperometry for the fast quantification of free and bound toxins.
Interconversion between a silaimine and an aminosilylene supported by an iminophosphonamide ligand
Authors: Takahashi Shintaro , Ishii Akihiko , Nakata Norio
Published: March 2021

Silaimine exists in equilibrium with aminosilylene, the formation of which was confirmed using variable-temperature NMR experiments and a trapping reaction.
Dioxygen splitting at room temperature over distant binuclear transition metal centers in zeolites for direct oxidation of methane to methanol
Authors: Mlekodaj Kinga , Lemishka Mariia , Sklenak Stepan , Dedecek Jiri , Tabor Edyta
Published: March 2021

Binuclear transition metal ion structures in ferrierite can split O2 and direct oxidized methane to methanol at RT.
A dual-enzyme cleavable linker for antibody–drug conjugates
Authors: Bargh Jonathan D. , Walsh Stephen J. , Ashman Nicola , Isidro-Llobet Albert , Carroll Jason S. , Spring David R.
Published: March 2021

A 3-O-sulfo-β-galactose linker is cleaved by two lysosomal enzymes to release payloads from ADCs at targeted cancer cells.
Cubic ZnP2 nanowire growth catalysed by bismuth
Authors: Oh Seung Hwan , Kim Yong
Published: March 2021

The ZnP2 nanowires catalysed by bismuth had a cubic γ-ZnP2 structure, which is known to be stable only at pressures higher than 1.5 GPa, and its existence is a matter of debate.
Orientation-tunable InxGa1−xN nanowires with a high density of basal stacking faults for photoelectrochemical/photocatalytic applications
Authors: Yuan Ronghuo , Luo Qingyuan , Zhang Zenghui , Zheng Yufan , Feng Dengtang , Wang Defa , Hu Yan-Ling
Published: March 2021

InxGa1−xN nanowires grew along the m-direction (A-NWs) or semipolar-direction (B-NWs) with the presence of a high density of BSFs.
Influence of Mg-doping on the characteristics of ZnO photoanodes in dye-sensitized solar cells
Authors: Ringleb Andreas , Ruess Raffael , Hofeditz Nico , Heimbrodt Wolfram , Yoshida Tsukasa , Schlettwein Derck
Published: March 2021

The bandgap of ZnO nanoparticulate photoanodes was increased by Mg-doping and the impact on photoelectrochemical characteristics in dye-sensitized solar cells is discussed.
A robust, freeze-resistant and highly ion conductive ionogel electrolyte towards lithium metal batteries workable at −30 °C
Authors: Tang Jiaqi , Zhai Binbin , Liu Jianfei , Ren Wenhao , Han Yu , Yang Hui , Chen Yongsheng , Zhao Chuan , Fang Yu
Published: March 2021

The wide applications of lithium metal batteries have encountered a severe conductivity issue when operating in cold weather.
Boosting methane partial oxidation on ceria through exsolution of robust Ru nanoparticles
Authors: Carrillo A. J. , Navarrete L. , Laqdiem M. , Balaguer M. , Serra J. M.
Published: March 2021

Robust Ru nanoparticles created by exsolution enhanced the chemical looping methane reforming performance for stable syngas production and CO2 splitting
Single-crystal X-ray structural characterization, Hirshfeld surface analysis, electronic properties, NBO, and NLO calculations and vibrational analysis of the monomeric and dimeric forms of 5-nitro-2-oxindole
Authors: Sagdinc Seda Gunesdogdu , Akcay Banu Kevser , Yildiz Salih Zeki , Isik Ilknur Baldan
Published: March 2021

The information of interactions is given by RDG versus sign(λ2)ρ product of the sign of the second largest eigenvalue of electron density Hessian matrix and electron density) investigated by RDG surface analysis.
Transition metal oxide and chalcogenide-based nanomaterials for antibacterial activities: an overview
Authors: Tang Yanan , Qin Zhen , Yin Shengyan , Sun Hang
Published: March 2021

This review summarizes the recent advances of transition metal oxide and chalcogenide-based antibacterial nanomaterials, with emphasis on their inactivation mechanisms and highlighting their practical applications.
Copper based on diaminonaphthalene-coated magnetic nanoparticles as robust catalysts for catalytic oxidation reactions and C–S cross-coupling reactions
Authors: Yarmohammadi Nasrin , Ghadermazi Mohammad , Mozafari Roya
Published: March 2021

This green-based catalyst with non-toxic materials and high efficiency is used in organic reactions.
Elucidating the role of GRIM-19 as a substrate and allosteric activator of pro-apoptotic serine protease HtrA2
Authors: Kummari Raghupathi , Dutta Shubhankar , Patil Shubhangi , Mudrale Snehal Pandav , Bose Kakoli
Published: March 2021

HtrA2 (high-temperature requirement A2) and GRIM-19 (gene associated with retinoic and interferon-induced mortality 19 protein) are involved in various biological functions with their deregulation leading to multiple diseases. Although it is known that the interaction between GRIM-19 with HtrA2 promotes the pro-apoptotic activity of the latter, the mechanistic details remained elusive till date. Moreover, designing allosteric modulators of HtrA2 remains obscure due to lack of adequate information on the mode of interaction with its natural substrates cum binding partners. Therefore, in this study, we have unfolded the interaction between HtrA2 and GRIM-19 so as to understand its subsequent functional repercussions. Using in silico analyses and biochemical assays, we identified the region in GRIM-19 that is involved in protein–protein interaction with HtrA2. Furthermore, we have presented a comprehensive illustration of HtrA2's cleavage site specificity. Quantitative analysis using enzyme kinetics underscored the role of GRIM-19 in significant allosteric activation of HtrA2. Overall, this is an extensive study that not only defines HtrA2–GRIM-19 interaction, but also creates a framework for developing strategies toward allosteric regulation of HtrA2 for future therapeutic interventions.
Combining automotive radar and LiDAR for surface detection in adverse conditions
Authors: Wallace Andrew M. , Mukherjee Saptarshi , Toh Bemsibom , Ahrabian Alireza
Published: March 2021

Automotive radar and light detection and ranging (LiDAR) sensors have complementary strengths and weaknesses for 3D surface mapping. We present a method using Markov chain Monte Carlo sampling to recover surface returns from full‐wave longitudinal signals that takes advantage of the high spatial resolution of the LiDAR in range, azimuth and elevation together with the ability of the radar to penetrate obscuring media. The approach is demonstrated using both simulated and real data from an automotive system.
A location-allocation model for quality-based blood supply chain under IER uncertainty
Authors: Moslemi Shiva , Pasandideh Seyed Hamid Reza
Published: March 2021

Providing blood with high quality at the lowest cost and the shortest time is main challenge of blood supply chain management. This paper presents a new model for designing a dynamic and three level blood supply chain incorporating the quality issues. The proposed model intends to locate facilities, and to determine the best strategy for blood allocation by minimizing both cost and time and maximizing the customer satisfaction based on quality of blood delivery. In order to deal with consideration of real world, intricacies such as blood freshness, both separation and apheresis extraction methods, Cross match to Transfusion ratio (C/T) and equipment failure have been involved. Also, Interval Evidential Reasoning (IER) approach is applied to handle the uncertainty of blood product demand. Since the proposed model is NP-hard, MOPSO and NSGAII algorithms are utilized to solve it. Finally, to demonstrate the applicability of the problem some numerical examples are designed in different sizes and the most favorable algorithm is determined using TOPSIS method.
Managing strategies of product quality and price based on trust under different power structures
Authors: Fu Xiao , Liu Shuchun , Shen Wendi , Han Guanghua
Published: March 2021

This paper investigates the quality and pricing decisions in a supply chain consists of one retailer and two manufacturers. The retailer updates the trust value to manufacturers based on the historical information of product quality to determine the actual order quantity. We propose four game models by considering two situations, i.e., manufacturer-dominant scenario and retailer-dominant scenario. Based on theoretical and numerical analysis, we obtain a series of valuable management insights. For example, when a manufacturer with unreliable product quality is the leader and competes with another reliable manufacturer, the retailer’s profit would eventually surpass that of two stronger manufacturers. When the retailer is the leader, the retailer’s profit is often greater when two manufacturers engage in the Stackelberg game rather than that in Bertrand game, and the manufacturer with unreliable product quality can make profit no less than that of another manufacturer with reliable quality.
Glukosemessmethoden und ihr Einsatz
Authors: Pleus Stefan , Kaiser Patricia , Haug Cornelia
Published: March 2021

In Deutschland werden verschiedene Messmethoden für die Glukosemessung eingesetzt. In der Heilkunde, d. h. der Anwendung durch medizinisches Fachpersonal im Rahmen der Gesundheitsversorgung, sind dies Laboranalysesysteme und Systeme zur patientennahen Sofortdiagnostik, während für die Verlaufskontrolle durch Menschen mit Diabetes Systeme zur Selbstmessung der Blutglukose oder zum kontinuierlichen Glukosemonitoring eingesetzt werden. Die praktischen Aspekte, einschließlich Präanalytik, die bei der Verwendung berücksichtigt werden müssen, hängen dabei stark vom jeweiligen Messsystem ab. Auch die rechtlichen Rahmenbedingungen für den Einsatz der Messsysteme variieren und müssen berücksichtigt werden. Während die Qualitätssicherung beim Einsatz in der Heilkunde gut standardisiert ist, weist sie bei der Selbstmessung durch Menschen mit Diabetes Lücken auf.
Predictive value of endoscopic esophageal findings for residual esophageal cancer after neoadjuvant chemoradiotherapy
Authors: van der Bogt Ruben D. , van der Wilk Berend J. , Nikkessen Suzan , Krishnadath Kausilia K. , Schoon Erik J. , Oostenbrug Liekele E. , Siersema Peter D. , Vleggaar Frank P. , Doukas Michael , van Lanschot J. Jan B. , Spaander Manon C. W.
Published: March 2021

Background Endoscopic evaluation of the esophageal mucosa may play a role in an active surveillance strategy after neoadjuvant chemoradiotherapy (nCRT) for esophageal cancer. This study investigated the yield of endoscopic findings for detection of residual disease.

Methods Patients from the multicenter preSANO cohort, who underwent nCRT followed by surgery for esophageal or junctional cancer, were included. Upper endoscopy was performed 6 and 12 weeks after nCRT. Patients with residual disease at 6 weeks underwent immediate surgery. Endoscopic records were reviewed for presence of stenosis, suspicion of residual tumor, scar tissue, and ulceration. Presence and type of endoscopic findings were compared with outcome of the resection specimen.

Results 118 of 156 patients (76 %) had residual disease in the resection specimen. Endoscopic suspicion of residual tumor was significantly associated with presence of residual disease. At 6 weeks, 40/112 patients with residual disease and 4/33 patients with complete response had endoscopic suspicion of residual tumor (36 % vs. 12 %; P = 0.01), while this was reported in 16/73 and 0/28 patients, respectively, at 12 weeks (22 % vs. 0 %; P < 0.01). Positive predictive value of endoscopic suspicion of residual tumor was 91 % at 6 weeks and 100 % at 12 weeks. Endoscopic findings of non-passable stenosis, passable stenosis, scar tissue, or ulceration were not associated with residual disease.

Conclusions Endoscopic suspicion of residual tumor was the only endoscopic finding associated with residual disease. Based on its positive predictive value, this endoscopic finding may contribute to the diagnostic strategy used in active surveillance.
Smoothing Corrections for Improving Sample Size Recalculation Rules in Adaptive Group Sequential Study Designs
Authors: Herrmann Carolin , Rauch Geraldine
Published: March 2021

Background An adequate sample size calculation is essential for designing a successful clinical trial. One way to tackle planning difficulties regarding parameter assumptions required for sample size calculation is to adapt the sample size during the ongoing trial.

This can be attained by adaptive group sequential study designs. At a predefined timepoint, the interim effect is tested for significance. Based on the interim test result, the trial is either stopped or continued with the possibility of a sample size recalculation.

Objectives Sample size recalculation rules have different limitations in application like a high variability of the recalculated sample size. Hence, the goal is to provide a tool to counteract this performance limitation.

Methods Sample size recalculation rules can be interpreted as functions of the observed interim effect. Often, a “jump” from the first stage's sample size to the maximal sample size at a rather arbitrarily chosen interim effect size is implemented and the curve decreases monotonically afterwards. This jump is one reason for a high variability of the sample size. In this work, we investigate how the shape of the recalculation function can be improved by implementing a smoother increase of the sample size. The design options are evaluated by means of Monte Carlo simulations. Evaluation criteria are univariate performance measures such as the conditional power and sample size as well as a conditional performance score which combines these components.

Results We demonstrate that smoothing corrections can reduce variability in conditional power and sample size as well as they increase the performance with respect to a recently published conditional performance score for medium and large standardized effect sizes.

Conclusion Based on the simulation study, we present a tool that is easily implemented to improve sample size recalculation rules. The approach can be combined with existing sample size recalculation rules described in the literature.
Research impact evaluation and academic discourse
Authors: Wróblewska Marta Natalia
Published: March 2021

The introduction of ‘impact’ as an element of assessment constitutes a major change in the construction of research evaluation systems. While various protocols of impact evaluation exist, the most articulated one was implemented as part of the British Research Excellence Framework (REF). This paper investigates the nature and consequences of the rise of ‘research impact’ as an element of academic evaluation from the perspective of discourse. Drawing from linguistic pragmatics and Foucauldian discourse analysis, the study discusses shifts related to the so-called Impact Agenda on four stages, in chronological order: (1) the ‘problematization’ of the notion of ‘impact’, (2) the establishment of an ‘impact infrastructure’, (3) the consolidation of a new genre of writing–impact case study, and (4) academics’ positioning practices towards the notion of ‘impact’, theorized here as the triggering of new practices of ‘subjectivation’ of the academic self. The description of the basic functioning of the ‘discourse of impact’ is based on the analysis of two corpora: case studies submitted by a selected group of academics (linguists) to REF2014 (no = 78) and interviews (n = 25) with their authors. Linguistic pragmatics is particularly useful in analyzing linguistic aspects of the data, while Foucault’s theory helps draw together findings from two datasets in a broader analysis based on a governmentality framework. This approach allows for more general conclusions on the practices of governing (academic) subjects within evaluation contexts.
A critical juncture in universal healthcare: insights from South Korea’s COVID-19 experience for the United Kingdom to consider
Authors: Heo Kyungmoo , Jeong Keonyeong , Lee Daejoong , Seo Yongseok
Published: March 2021

Universal healthcare systems have undergone a severe stress test in the form of the ongoing COVID-19 pandemic. With respect to the system-embedded allocation of decision-making powers and responsibilities among actors, different modalities have been revealed in the COVID-19 responses of South Korea and the UK, respectively. This article compares and analyzes how these two countries’ healthcare systems have reacted to COVID-19. Although both have implemented similar responsive measures, the UK has recorded a higher number of confirmed cases per thousand people and a higher death rate. Based on the analysis on which this paper is built, the key differences between the two systems are the UK system’s lack of: (1) appropriate medical equipment and technologies along with the human resources; and (2) flexible policy options to incentivize healthcare providers and induce cooperation from the public in a time of national crisis. The UK’s healthcare system is now approaching a critical juncture. The expansion of internal competition, which was introduced to the system in 1991, can serve as means of initiating a resolution to the above-mentioned issues and further reform its system. Under the UK government’s close supervision and precise control, allowing non-reimbursable special medical treatment in the system and widening public choice of medical services would be a suitable policy approach promoting internal competition while at the same time maintaining the UK’s devotion to universal healthcare. The underlying implication of internal competition though is the sharing of decision-making powers and responsibilities with societal and private sectors by inducing and facilitating participation at all levels. Fighting against COVID-19 however is widely considered ‘all-out-war.’ Under the UK government’s supervision and control, it is time for society to step up and fight the pandemic together.
Modelling the end of the Acheulean at global and continental levels suggests widespread persistence into the Middle Palaeolithic
Authors: Key Alastair J. M. , Jarić Ivan , Roberts David L.
Published: March 2021

The Acheulean is the longest cultural tradition ever practised by humans, lasting for over 1.5 million years. Yet, its end has never been accurately dated; only broad 300–150 thousand years ago (Kya) estimates exist. Here we use optimal linear estimation modelling to infer the extinction dates of the Acheulean at global and continental levels. In Africa and the Near East the Acheulean is demonstrated to end between 174 and 166 Kya. In Europe it is inferred to end between 141 and 130 Kya. The Acheulean’s extinction in Asia occurs later (57–53 Kya), while global models vary depending on how archaeological sites are selected (107–29 Kya). These models demonstrate the Acheulean to have remained a distinct cultural tradition long after the inception of Middle Palaeolithic technologies in multiple continental regions. The complexity of this scenario mirrors the increasingly dynamic nature of the Middle Pleistocene hominin fossil record, suggesting contemporaneous hominin populations to have practised distinct stone-tool traditions.
Synchronous linear constraint system games
Authors: Goldberg Adina
Published: March 2021

Mathematical models of quantum mechanics can be studied and distinguished using nonlocal games. We discuss a class of nonlocal games called synchronous linear constraint system (syncLCS) games. We unify two algebraic approaches to studying syncLCS games and relate these games to nonlocal games played on graphs, known as graph isomorphism games. In more detail, syncLCS games are nonlocal games that verify whether or not two players share a solution to a given system of equations. Two algebraic objects associated with these games encode information about the existence of perfect strategies. They are called the game algebra and the solution group. Here, we show that these objects are essentially the same, i.e., the game algebra is a suitable quotient of the group algebra of the solution group. We also demonstrate that syncLCS games are equivalent to graph isomorphism games on a pair of graphs parameterized by the linear system.
Elucidating possible crystallographic origins of wake-up mechanisms in ferroelectric hafnia
Authors: McMitchell Sean R. C. , Clima Sergiu , Ronchi Nicolo' , Banerjee Kaustuv , Celano Umberto , Popovici Mihaela , Di Piazza Luca , Van den Bosch Geert , Van Houdt Jan
Published: March 2021

The wake-up in doped hafnia ferroelectric devices is an extremely important process to understand in order to integrate these materials successfully into working ferroelectric memory devices. The crystallographic origins of this process are clarified with three main mechanisms. Strain relaxation in the ferroelectric orthorhombic phase led to an adjustment of the unit cell volume toward a “bulk-like” value. The undistorted cell allowed for easier polarizability within the unit cell, allowing higher polarization. Reversible phase transformations between the tetragonal and orthorhombic phases depend on the nature of the strain. Finally, a model is developed describing grain reorientation, inducing a 90° rotation of the orthorhombic unit cell and allowing the phase to respond to the E-field more readily under cycling.
Magnetic reconnection and thermal equilibration
Authors: Boozer Allen H.
Published: March 2021

When a magnetic field is forced to evolve on a time scale τev, as by footpoint motions driving the solar corona or non-axisymmetric instabilities in tokamaks, the magnetic field lines undergo large-scale changes in topology on a time scale approximately an order of magnitude longer than τev. But the physics that allows such changes operates on a time scale eight or more orders of magnitude slower. An analogous phenomenon occurs in air. Temperature equilibration occurs on a time scale approximately an order of magnitude longer than it takes air to cross a room, τev, although the physical mechanism that allows temperature equilibration is approximately four orders of magnitude slower than τev. The use of Lagrangian coordinates allows the fundamental equations to be solved and both phenomena explained. The theories of thermal equilibration and magnetic reconnection are developed in parallel to help readers obtain an understanding of the importance and implications of analyses using Lagrangian coordinates.
High-resolution x-ray radiography with Fresnel zone plates on the University of Rochester’s OMEGA Laser Systems
Authors: Marshall F. J. , Ivancic S. T. , Mileham C. , Nilson P. M. , Ruby J. J. , Stoeckl C. , Scheiner B. S. , Schmitt M. J.
Published: March 2021

Experiments performed at the Laboratory for Laser Energetics with a continuous-wave (cw) x-ray source and on the OMEGA and OMEGA EP Laser Systems [Boehly et al., Opt. Commun. 133, 495 (1997) and Waxer et al., Opt. Photonics News 16, 30 (2005)] have utilized a Fresnel zone plate (FZP) to obtain x-ray images with a spatial resolution as small as ∼1.5 μm. Such FZP images were obtained with a charge-coupled device or a framing camera at energies ranging from 4.5 keV to 6.7 keV using x-ray line emission from both the cw source and high-intensity, laser-beam–illuminated metal foils. In all cases, the resolution test results are determined from patterns and grids backlit by these sources. The resolutions obtained are shown to be due to a combination of the spectral content of the x-ray sources and detector resolution limited by the magnification of the images (14× to 22×). High-speed framing cameras were used to obtain FZP images with frame times as short as ∼30 ps. Double-shell implosions on OMEGA were backlit by laser-irradiated Fe foils, thus obtaining a framing-camera–limited, FZP-image resolution of ∼3 μm–4 μm.
The Liouville type theorem for the stationary magnetohydrodynamic equations
Authors: Fan Huiying , Wang Meng
Published: March 2021

In this paper, we focused on demonstrating the Liouville type theorem for the stationary magnetohydrodynamic equations. First, we improve the well-known L92(R3) result logarithmically. In addition, we are aimed to an asymptotic formula for an integral involving the total head pressure Q=12|u|2+|h|2+p and its derivative over domains enclosed by level surfaces of Q, which provides us with the additional sufficient condition for the triviality of solution for the magnetohydrodynamic equations.
New atoms-in-molecules dispersion models for use in ab initio derived force fields
Authors: Welsh Ivan D. , Crittenden Deborah L.
Published: March 2021

Recently, substantial research efforts have gone into bridging the accuracy–efficiency gap between parameterized force field models and quantum chemical calculations by extracting molecule-specific force fields directly from ab initio data in a robust and automated manner. One of the challenging aspects is deriving localized atomic polarizabilities for pairwise distributed dispersion models. The Tkatchenko–Scheffler model is based upon correcting free-atom C6 coefficients according to the square of the ratio of the atom-in-molecule volume to the free-atom volume. However, it has recently been shown that a more accurate relationship can be found if static atomic polarizabilities are also taken into account. Using this relationship, we develop two modified Tkatchenko–Scheffler dispersion models and benchmark their performance against SAPT2+3 reference data and other commonly used dispersion models.
Imidazole-based ionic liquids as rheological modifiers of heavy crude oil: An experimental and theoretical study
Authors: Martínez-Mora Omar , Campa-Guevara Diana , Meza-Gordillo Rocío , Sánchez Rodrigo , Salas-Reyes Magali , Domínguez José Manuel , Matus Myrna H. , Domínguez Zaira
Published: March 2021

Two series of imidazolium-based ionic liquids (ILs) were tested as rheological modifiers of heavy crude oils. ILs with the 1-butyl-3-alkylimidazolium cation optimize the effect on viscosity at low concentrations, whereas those with the 1-benzyl-3-alkylimidazolium cation are similarly effective only at higher concentrations, which is due to a stronger IL–IL interaction with respect to the IL–asphaltene interaction. The most effective ILs were [C6bim][PF6], [phetbim][PF6], and [C9bim][NTf2], with viscosity falling in the order of 44.0%, 38.2%, and 32.9%, respectively. An analysis of structural features suggests that the type of anion and the strength of the ion pair interaction play an important role in the capacity of the salts to interact with the crude oil components. In addition, computational methodologies, such as atoms in molecules and non-covalent interactions, were used to analyze the main intermolecular interactions between the most effective [C6bim][PF6] and two different substructures of an asphaltene model. According to these results, hydrogen bonding (F⋯H–C, F⋯H–N, and O⋯H–C), C–H–π, and van der Waals interactions contribute to the breaking up of the π–π stacking interactions between the complexes resulting from the self-association of the aromatic compounds; as a consequence, the crude oil viscosity decreases.
Emergence and synchronization of a reversible core in a system of forced adaptively coupled Kuramoto oscillators
Authors: Emelianova Anastasiia A. , Nekorkin Vladimir I.
Published: March 2021

We report on the phenomenon of the emergence of mixed dynamics in a system of two adaptively coupled phase oscillators under the action of a harmonic external force. We show that in the case of mixed dynamics, oscillations in forward and reverse time become similar, especially at some specific frequencies of the external force. We demonstrate that the mixed dynamics prevents forced synchronization of a chaotic attractor. We also show that if an external force is applied to a reversible core formed in an autonomous case, the fractal dimension of the reversible core decreases. In addition, with increasing amplitude of the external force, the average distance between the chaotic attractor and the chaotic repeller on the global Poincaré secant decreases almost to zero. Therefore, at the maximum intersection, we see a trajectory belonging approximately to a reversible core in the numerical simulation.
Numerical analysis of the nonlinear free surface flow around an advancing ship using moving particle semi-implicit method
Authors: Pak CholJun , Han PokNam , Ri KwangChol , Ri YongKwang , Hwang InChol
Published: March 2021

This paper presents a methodology to simulate the nonlinear free surface flow around an advancing ship. This methodology is based on the Moving Particle Semi-implicit (MPS) method, which is widely used to simulate the incompressible fluid flow. In this paper, the original MPS method is modified in order to analyze effectively the nonlinear free surface flow around an advancing ship. Several treatment techniques are newly proposed, and the original MPS method is modified by combining these techniques with other previous research studies. The proposed techniques include the Laplacian compensation model in the region near the body boundary, the collision model between fluid particles and wall particles, and some treatments for the opened boundary. The accuracy of the modified MPS method is verified through the numerical simulations on two benchmark problems for the performance evaluation of the particle methods and on the flows around both the wedged body and model ship. The numerical results demonstrate that the modified MPS method can be effectively applied to the simulation of nonlinear free surface flow around an advancing ship in marine engineering.
Modified FFT-based method for the calculations of the thin superconductors with transport current
Authors: Wang Sijian , Yong Huadong , Zhou Youhe
Published: March 2021

The Fast Fourier Transform (FFT) method was used to simulate the magnetization problems of the thin film in a perpendicular magnetic field. There are few works on the calculations of the superconducting film with transport current using the FFT-based method. To take into account the effect of the transport current, we modify the previous method and then use it to calculate the electromagnetic behaviors of the thin film. This modified method is implemented by transforming the boundary conditions of the transport current. The numerical results are compared with the integral solution for accuracy and the T–A formulation in finite elements for efficiency. The results show that the FFT-based method is an efficient method for the calculations of the superconducting film carrying transport current. Next, we simplify the 2D film problems to the infinitely long strip situation and use the modified method to calculate the strip stack problems. The results indicate that the modified FFT-based method is also valid for the computation of the strip stack problems and efficient as the number of strips is not very large.
Monolayer molecular sensing using infrared leaky waveguide mode
Authors: Zhang Tieyan , He De , Liu Lu , Wulan Qiqige , Yu Jiachen , Li Zhe , Liu Zhijun
Published: March 2021

Surface-enhanced infrared absorption spectroscopy is attractive for molecular sensing due to its access to chemical bonds with high detection sensitivity. Such a spectroscopic method typically operates on localized resonances in subwavelength structured antennas and metamaterials. In this paper, we demonstrate monolayer octadecanethiol detection by using the leaky guided mode in a metal–insulator–metal waveguide, whose angle-tunable dispersion enables coupling to molecular vibrations with a frequency-variable optical resonance. Our results show that, by changing the incident angle from 15° to 75°, the resonance frequency of the leaky guided mode is scanned around the CH2 vibration modes with frequency detuning from −200 cm−1 to 350 cm−1 in wavenumber. As the frequency detuning increases, the vibration signal of both the CH2 symmetric and asymmetric modes increases first and then decreases. The maximum vibration signal of 1%–1.5% is reached at positive and negative frequency detuning values of ±100 cm−1. These sensing properties are explained with a coupled-oscillator model, which suggests that both enhanced near-field and coupling strength between the optical resonance and molecular vibration play an important role for the optimal sensing performance.
The curling probe: A numerical and experimental study. Application to the electron density measurements in an ECR plasma thruster
Authors: Boni Federico , Jarrige Julien , Désangles Victor , Minea Tiberiu
Published: March 2021

The measurement of electron density is a key issue in understanding and controlling plasma applications. To date, plasma density in electric thrusters has been mainly evaluated with electrostatic techniques, such as the Langmuir probe, which could be quite invasive. In this paper, we propose the application of a microwave resonant probe, the curling probe, to the diagnostic of an electrodeless plasma thruster. The measurable electron density range and the probe accuracy are found to be limited by the probe natural frequency. We present the numerical study and the experimental characterization of three curling probes with different natural frequencies (700, 1400, and 3000 MHz, approximately). First, an analytical equation of the natural frequency as a function of geometrical parameters is drawn from 2D numerical simulations. Then, a procedure based on solid dielectric etalons is proposed for the absolute calibration of the probe. Finally, measurements are performed in the plume of an electron cyclotron resonance plasma thruster. Electron densities from 108 to 1011 cm−3 have been obtained in agreement with hairpin and Langmuir probes results. A wall-embedded probe has enabled measurements inside the thruster source with minimal plasma perturbation. A possible curling probe configuration, embedded in a reactor wall, is proposed as a fully non-invasive diagnostic for plasma sources.
Upgrade of the gated laser entrance hole imager G-LEH-2 on the National Ignition Facility
Authors: Chen Hui , Golick B. , Palmer N. , Carpenter A. , Claus L. D. , Dayton M. , Dean J. , Durand C. , Funsten B. , Petre R. B. , Hardy C. M. , Hill J. , Holder J. , Hurd E. , Izumi N. , Kehl J. , Khan S. , Macaraeg C. , Sanchez M. O. , Sarginson T. , Schneider M. B. , Trosseille C.
Published: March 2021

A major upgrade has been implemented for the ns-gated laser entrance hole imager on the National Ignition Facility (NIF) to obtain high-quality data for Hohlraum physics study. In this upgrade, the single “Furi” hCMOS sensor (1024 × 448 pixel arrays with two-frame capability) is replaced with dual “Icarus” sensors (1024 × 512 pixel arrays with four-frame capability). Both types of sensors were developed by Sandia National Laboratories for high energy density physics experiments. With the new Icarus sensors, the new diagnostic provides twice the detection area with improved uniformity, wider temporal coverage, flexible timing setup, and greater sensitivity to soft x rays (<2 keV). These features, together with the fact that the diagnostic is radiation hardened and can be operated on the NIF for high neutron yield deuterium–triterium experiments, enable significantly greater return of data per experiment.
The effect of H radicals on microstructure and electrical and optical properties of sputtered ZnO:Al films
Authors: Hao Changshan , Peng Jingjing , Zhong Yanli , Zhang Xuan , Lei Pei , Huo Zhongqi
Published: March 2021

ZnO:Al films were prepared by magnetron sputtering at room temperature. During the growth process, H radicals produced by radio frequency power sources were in situ introduced into ZnO:Al films. By injecting H radicals, the content of Al in ZnO:Al films increased from 3.4 at. % to 6.1 at. %, which could be ascribed to the reaction between H radicals and ZnO as well as the resputtering of the Zn element. Surface morphologies of ZnO:Al films were tuned from smooth shape to sunflower seed-like. Furthermore, ZnO:Al films without injecting H radicals showed highly c-axis preferential orientation and then nearly became amorphous with the addition of H radicals, which corresponds to the results of Raman spectra. The grain boundary potentials decreased due to the removal of oxygen at grain boundaries and an amount of Vo was produced, which was proved by Raman and x-ray photoelectron spectroscopy results. The optimal resistivity of as-grown ZnO:Al films co-doped with H radicals was 1.5 × 10−3 Ω cm at an H2 ratio of 2.3%. The variation of the carrier concentration for annealed ZnO:Al films at different H2 ratios supported the existence of H interstitials and Vo. The optical bandgap varied from 3.44 eV to 3.71 eV with increasing H radicals.
A microwave detector based on spoof surface plasmon polaritons structure
Authors: Liu Leilei , Jiang Dingwei
Published: March 2021

In this paper, a Schottky diode detector based on spoof surface plasmon polariton (SPP) structure is reported. The detector consists of an input matching network, a Schottky diode, and an output filtering network. The proposed detector is designed using a step impedance section and λ/4 radial stub integrated in the circuit. Compared with the conventional microwave detector, experimental results show that the proposed detector achieves 31% improvement of detection sensitivity with the high input radio frequency (RF) power and 95% improvement of the detection sensitivity with the low input RF power by the SPPs. The proposed detector is attractive for use in aircraft, vehicles, and wireless communication due to its miniaturization, low-cost, and easy fabrication with planar circuits.
Neural network potential energy surface for the low temperature ring polymer molecular dynamics of the H2CO + OH reaction
Authors: Mazo-Sevillano Pablo del , Aguado Alfredo , Roncero Octavio
Published: March 2021

A new potential energy surface (PES) and dynamical study of the reactive process of H2CO + OH toward the formation of HCO + H2O and HCOOH + H are presented. In this work, a source of spurious long range interactions in symmetry adapted neural network (NN) schemes is identified, which prevents their direct application for low temperature dynamical studies. For this reason, a partition of the PES into a diabatic matrix plus a NN many-body term has been used, fitted with a novel artificial neural network scheme that prevents spurious asymptotic interactions. Quasi-classical trajectory (QCT) and ring polymer molecular dynamics (RPMD) studies have been carried on this PES to evaluate the rate constant temperature dependence for the different reactive processes, showing good agreement with the available experimental data. Of special interest is the analysis of the previously identified trapping mechanism in the RPMD study, which can be attributed to spurious resonances associated with excitations of the normal modes of the ring polymer.
Boronic acid with high oxidative stability and utility in biological contexts
Authors: Graham Brian J. , Windsor Ian W. , Gold Brian , Raines Ronald T.
Published: March 2021

Significance

Like thiols, boronic acids are unstable to oxidation in biological contexts, limiting their utility. We discovered that the rate-limiting step in the oxidation of a boronic acid can be slowed by the installation of a pendant carboxyl group that is a ligand to the boron atom. The ensuing boronic acid is 10,000-fold more resistant to oxidation. Experimental and computational analyses reveal that the orientational constraints and electronic effects imposed by the carboxyl group act as intended, slowing the rate-limiting step during oxidation. The new boronic acid retains the useful attributes of simple boronic acids such as forming reversible covalent bonds with saccharides and a protein and could be useful in chemical biology, medicinal chemistry, and allied fields.
The role of perceived restorative capacity and crowding on satisfaction: a study in different tourist spaces (El papel de la capacidad restauradora percibida y el hacinamiento sobre la satisfacción: un estudio en diferentes espacios turísticos)
Authors: Arbelo Kevin , Delgado Naira , Ruiz Cristina , Hernández-Fernaud Estefanía
Published: March 2021

The objective of this study is to analyse the effect of perceived crowding and perceived restorative capacity on tourist satisfaction in different tourist environments. After visiting three tourist spaces, 1,958 tourists were surveyed. Three scales were used: (1) perceived restorative capacity of tourist environments; (2) perceived crowding; and (3) satisfaction, enjoyment and intention to recommend. The results showed that the perception of restorative capacity is intensely related to satisfaction measurements. In all three tourist spaces, satisfaction decreases as perceived restorative capacity drops. Likewise, the perception of crowding shows an inverse relationship with satisfaction; tourists who had a strong sense of being disturbed over the number of people at the site had lower levels of satisfaction, enjoyment and intention to recommend. The results show the important role played by perceived restorative capacity and the perception of crowding on tourist satisfaction and the need to explore the role of psycho-environmental variables on satisfaction by incorporating the unique features of the place visited.
Separating spins by dwell time of electrons across parallel double δ-magnetic-barrier nanostructure applied by bias
Authors: Chen Sai-Yan , Lu Mao-Wang , Cao Xue-Li
Published: March 2021

The dwell time and spin polarization (SP) of electrons tunneling through a parallel double δ-magnetic-barrier nanostructure in the presence of a bias voltage is studied theoretically in this work. This nanostructure can be constructed by patterning two asymmetric ferromagnetic stripes on the top and bottom of InAs/Al
x
In1 – x
As heterostructure, respectively. An evident SP effect remains after a bias voltage is applied to the nanostructure. Moreover, both magnitude and sign of spin-polarized dwell time can be manipulated by properly changing the bias voltage, which may result in an electrically-tunable temporal spin splitter for spintronics device applications.
Device design based on the covalent homocoupling of porphine molecules*
Authors: Qu Minghui , He Jiayi , Liu Kexin , Cao Liemao , Zhao Yipeng , Zeng Jing , Zhou Guanghui
Published: March 2021

Porphine has a great potential application in molecular electronic devices. In this work, based on the density functional theory (DFT) and combining with nonequilibrium Green’s function (NEGF), we study the transport properties of the molecular devices constructed by the covalent homocoupling of porphine molecules conjunction with zigzag graphene nanoribbons electrodes. We find that different couple phases bring remarkable differences in the transport properties. Different coupling phases have different application prospects. We analyze and discuss the differences in transport properties through the molecular energy spectrum, electrostatic difference potential, local density of states (LDOS), and transmission pathway. The results are of great significance for the design of porphine molecular devices in the future.