bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical analyses of exponential time‐differencing schemes for the solution of atmospheric models
Authors: Calandrini Sara , Pieper Konstantin , Gunzburger Max 
Published: January 2021

AbstractIn high‐resolution numerical weather prediction models, fast‐moving acoustic waves must be treated in a stable manner. Among the implicit–explicit (IMEX) schemes used for the solution of these models, horizontally explicit, vertically implicit (HEVI) methods show good stability and scalability on massively parallel machines. In this work, we present two classes of exponential time‐differencing (ETD) methods for atmospheric models that use a HEVI splitting strategy, one being a three‐stage method with the addition of artificial diffusion, the second based on a Strang splitting approach. The stability properties of the methods are analyzed and numerical examples are provided, which compare time‐step restrictions and cost‐to‐accuracy ratios of the new methods with those for existing approaches.
Krylov solvers in a vertical‐slice version of the semi‐implicit semi‐Lagrangian AROME model
Authors: Burgot T. , Auger L. , Bénard P. 
Published: January 2021

AbstractTo circumvent the scalability problem due to global communication involved in spectral transforms, a vertical‐slice version of the dynamical core where all calculations are performed in grid‐point space has been built for AROME, Météo‐France's operational limited‐area model. It is shown in an idealized but nevertheless physically relevant framework that, despite this major change, it is possible to keep the other main characteristics of the model (constant‐coefficient semi‐implicit scheme, semi‐Lagrangian transport scheme, A‐grid, mass‐based coordinate, etc.). A Krylov solver is used to solve the implicit problem. Using the solution given by the spectral model as a reference in terms of quality and required accuracy in an operational context, the chosen parameters of the Krylov solver are carefully tuned to maximize its convergence speed. The Krylov solver consists of several applications of a sparse operator, whose stencil is similar to that of the operator applied during the small time step of split‐explicit schemes traditionally used in HEVI (Horizontally Explicit/Vertically Implicit) models. HEVI models are considered particularly scalable in the current parallelization paradigm and are used as a reference for scalability in this study. Results show that a fast convergence can be reached, such that only a few applications of the sparse operator are required. This suggests an improvement in scalability compared to the spectral version. Experiments have been formulated regardless of the future strategy considered for temporal and spatial resolutions, i.e., increasing spatial resolution while either maintaining a high Courant number or reducing it.
Angular distributions and critical minima in the elastic scattering of electrons by atomic copper
Authors: Shorifuddoza M. , Das Pretam K. , Kabir Raihan , Haque A. K. Fazlul , Uddin M. Alfaz 
Published: January 2021

AbstractDirac relativistic partial wave analysis has been employed to analyze the angular distributions and critical minima, along with maximum spin polarization, for the elastic scattering of electrons from copper atoms over the energy range of 1 to 2000 eV. Integrated elastic, inelastic, total, and momentum transfer cross sections have also been calculated. This work uses a complex electron‐atom optical potential that includes static, exchange, correlation‐polarization, and absorption potentials. Comparison of our calculations with the available experimental data and other theoretical calculations shows satisfactory agreement. As far as we are concerned, critical minima and corresponding maximum spin polarization points have not yet been reported in the literature.
Lipid‐based therapies against SARS‐CoV‐2 infection
Authors: Alketbi Eman Humaid , Hamdy Rania , El‐Kabalawy Abdalla , Juric Viktorija , Pignitter Marc , A. Mosa Kareem , Almehdi Ahmed M. , El‐Keblawy Ali A. , Soliman Sameh S. M. 
Published: January 2021

SummaryViruses have evolved to manipulate host lipid metabolism to benefit their replication cycle. Enveloped viruses, including coronaviruses, use host lipids in various stages of the viral life cycle, particularly in the formation of replication compartments and envelopes. Host lipids are utilised by the virus in receptor binding, viral fusion and entry, as well as viral replication. Association of dyslipidaemia with the pathological development of Covid‐19 raises the possibility that exploitation of host lipid metabolism might have therapeutic benefit against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). In this review, promising host lipid targets are discussed along with potential inhibitors. In addition, specific host lipids are involved in the inflammatory responses due to viral infection, so lipid supplementation represents another potential strategy to counteract the severity of viral infection. Furthermore, switching the lipid metabolism through a ketogenic diet is another potential way of limiting the effects of viral infection. Taken together, restricting the access of host lipids to the virus, either by using lipid inhibitors or supplementation with exogenous lipids, might significantly limit SARS‐CoV‐2 infection and/or severity.
Robust intersample crossing of target sets with mixed‐integer linear programming
Authors: Afonso Rubens J. M. , Galvão Roberto K. H. 
Published: January 2021

AbstractThis note is concerned with the problem of crossing a target set between sample instants under the influence of bounded unknown disturbances. The proposed solution employs mixed‐integer linear programming and is less conservative compared with the standard approach of imposing pointwise‐in‐time constraints at the sample instants.
Low complexity visual UAV track navigation using long‐wavelength infrared
Authors: Rosser Kent , Nguyen Tran Xuan Bach , Moss Philip , Chahl Javaan 
Published: January 2021

AbstractVisual navigation is a commonly researched alternative to the use of global navigation satellite systems in challenging environments where satellite signals are not available. However, the vast majority of visual navigation techniques studied to date require scene illumination of some form. In this study, we use a low‐resolution long‐wave infrared (LWIR) image sensor sensitive to thermal emissivity within an optical flow processing engine to extend a low complexity track‐based navigation scheme for fixed wing aircraft to operate at night. A mixture of closed and open loop flight experiments conducted on a small UAV integrated with the new sensor demonstrate: accurate track‐based navigation in visual darkness; that the LWIR sensor performs equivalently to the benchmark optical flow sensor during daylight and continues to operate in low light; and that the LWIR sensor is able to detect suitable textures for operation at night across a wide span of altitudes. These results demonstrate utility of optical flow algorithms with low‐resolution thermal scenes as a novel aircraft navigation sensor for day and night operation.
Detecting rare haplotype association with two correlated phenotypes of binary and continuous types
Authors: Yuan Xiaochen , Biswas Swati 
Published: January 2021

AbstractMultiple correlated traits/phenotypes are often collected in genetic association studies and they may share a common genetic mechanism. Joint analysis of correlated phenotypes has well‐known advantages over one‐at‐a‐time analysis including gain in power and better understanding of genetic etiology. However, when the phenotypes are of discordant types such as binary and continuous, the joint modeling is more challenging. Another research area of current interest is discovery of rare genetic variants. Currently there is no method available for detecting association of rare (or common) haplotypes with multiple discordant phenotypes jointly. Our goal is to fill this gap specifically for two discordant phenotypes. We consider a rare haplotype association method for a binary phenotype, logistic Bayesian LASSO (univariate LBL) and its extension for two correlated binary phenotypes (bivariate LBL‐2B). Under this framework, we propose a haplotype association test with binary and continuous phenotypes jointly (bivariate LBL‐BC). Specifically, we use a latent variable to induce correlation between the two phenotypes. We carry out extensive simulations to investigate bivariate LBL‐BC and compare it with univariate LBL and bivariate LBL‐2B. In most settings, bivariate LBL‐BC performs the best. In only two situations, bivariate LBL‐BC has similar performance—when the two phenotypes are (1) weakly or not correlated and the target haplotype affects the binary phenotype only and (2) strongly positively correlated and the target haplotype affects both phenotypes in positive direction. Finally, we apply the method to a data set on lung cancer and nicotine dependence and detect several haplotypes including a rare one.
Isolation and Molecular Docking of Cytotoxic Secondary Metabolites from Two Red Sea Sponges of the Genus Diacarnus
Authors: Al‐Tarabeen Mousa , El‐Neketi Mona , Albohy Amgad , Müller Werner Ernst Georg , Rasheed Mohammed , Ebrahim Weaam , Proksch Peter , Ebada Sherif Saeed 
Published: January 2021

AbstractChemical investigation of methanol extracts from two Jordanian marine sponges belonging to genus Diacarnus: D. erythraeanus and D. ardoukobae (family Podospongiidae) afforded a series of norterpene cyclic peroxides namely; muqubilone A (1), sigmosceptrellin‐B (2), sigmosceptrellin‐B methyl ester (3), (+)‐methyl‐2‐epinuapapuanoate (4); (−)‐methyl‐2‐epinuapapuanoate (5) in addition to a macrolide derivative: latrunculin B (6). Chemical structures of isolated compounds were elucidated based on their 1D and 2D NMR and mass spectra as well as by comparison with the literature. All isolated compounds were assessed for their cytotoxic activity against the murine lymphoma (L5178Y) cell line. Among tested compounds, only (2–4) displayed significant cytotoxicity with IC50 values ranging from 1.2 to 6.4 μM. Molecular docking studies of isolated compounds suggested potential EGFR inhibition and the correlation between docking scores and biological data was strong based on Pearson's correlation coefficient (r=0.93).
Development of a 4‐Nitrophenylhydrazine Sensor Based on MgTi2O4⋅TiO2⋅Zn2TiO4 Nanomaterials
Authors: Abdus Subhan Md , Saha Pallab C. , Sumon Shamim A. , Alam M. M. , Asiri Abdullah M. , Al‐Mamun Mohammad , Rahman Mohammed M. 
Published: January 2021

AbstractThe synthesized MgTi2O4⋅TiO2⋅Zn2TiO4 nanomaterial was characterized by XRD (X‐Ray diffraction), SEM (Scanning electron microscopy), EDS (Energy dispersive x‐ray spectroscopy), FTIR (Fourier transform infrared spectroscopy) and PL (Photoluminescence) study. Particles size of MgTi2O4⋅TiO2⋅Zn2TiO4 nanomaterial was found to be 37.3 nm. PL and PLE (Photoluminescence excitation) spectra are showed several peaks including one red PL at 723 nm, when excited at 320 nm. Nanomaterial was subject to electrochemical sensor study. Thin layer of synthesized MgTi2O4⋅TiO2⋅Zn2TiO4 nanomaterials was fabricated onto the glassy carbon electrode (GCE) with conducting binder to result the working electrode of 4‐nitrophenylhydrazine (4‐NPHyd) sensor, which was applied successively to selectively detect the 4‐NPHyd in aqueous phase. The 4‐NPHyd chemical sensor exhibited high sensitivity with lower detection limit, long‐term stability in chemical environment and improved electrochemical responses during sensing performance. The linearity of calibration plot is obtained over the large linear dynamic range (LDR) from 0.1 nM to 0.1 mM of 4‐NPHyd. The sensitivity calculated from the slop of calibration plot (ratio of current to concentration of 4‐NPHyd) is 42.7215 μAmM−1cm−2 with detection limit (DL) of 0.02±0.001 nM at signal to noise ratio of 3(S/N). Therefore, the chemical sensor based on MgTi2O4⋅TiO2⋅Zn2TiO4 nanomaterials may be a promising highly sensitive sensor in electrochemical method for the effective detection of hazardous and carcinogenic chemicals in medical as well as biological sectors.
Mutual Performance Enhancement within Dual N‐doped TiO2/Si/C Nanohybrid Lithium‐Ion Battery Anode
Authors: Xie Shuang , Ji Qing , Xia Yonggao , Fang Kai , Wang Xiaoyan , Zuo Xiuxia , Cheng Ya‐Jun 
Published: January 2021

AbstractDual N‐doped TiO2/Si/C ternary nanohybrid has been successfully prepared via a facile solvothermal method. Polyethylene glycol (PEG) is applied to disperse TiO2 and silicon precursors. After polymerization with hexamethylene diisocyanate (HDI) and calcination, N‐doped TiO2 and carbon matrix are obtained. The contents of Si, TiO2 and C in N‐doped TiO2/Si/C are about 10 %, 72 % and 18 % respectively. N‐doped TiO2/Si/C shows an excellent electrochemical performance due to combined advantages of Si, TiO2 and C. The initial discharge/charge specific capacity of the N‐doped TiO2/Si/C is 658/548 mAh g−1 at a current of 0.1 A g−1 with a coulombic efficiency of 83 %. A reversible capacity of 538 mAh g−1 is achieved after 80 cycles. While at the high current of 5 A g1, the specific capacity of the N‐doped TiO2/Si/C can still reach 120 mAh g−1. Electrochemical impedance spectroscopy measurements prove the improved electric conductivity after N‐doping.
Utilization of Sawdust and Wood Ash as a Filler in Natural Rubber Composites
Authors: Kaewpruk Chalika , Boopasiri Supparoek , Poonsawat Choosak , Sae‐Oui Pongdhorn , Siriwong Chomsri 
Published: January 2021

AbstractThis study focuses on the feasibility of using sawdust (SD) and wood ash (WA) as a filler in natural rubber composite. Both SD and WA were characterized by several techniques prior to being incorporated into natural rubber (NR). Properties of the rubber composites filled with various loadings of SD and WA, including cure characteristics, mechanical properties and morphology, were measured. Results reveal that the particles of SD and WA are relatively large and irregular. The main compositions of SD are cellulose, lignin and hemicellulose whereas those of WA are SiO2, Al2O3, Fe2O3, carbonates and oxides of the alkali metals, namely CaO, MgO, Na2O, K2O, etc. After being incorporated into NR, hardness and modulus of the NR composites gradually increase with increasing SD and WA loadings. Compared with SD, WA provides a slightly lower magnitude of reinforcement, possibly due to its lower rubber‐filler interaction. However, the addition of WA significantly shortens the vulcanization time due to its high basicity. Interestingly, tensile strength of the NR composites is not significantly impaired with the addition of SD or WA up to 30 phr. Nevertheless, due to their relatively large particle size, both SD and WA show considerably lower magnitude of reinforcement than carbon black (CB). The results indicate the potential use of SD and WA as an inert filler for cost‐reduction purpose in the rubber industry which helps to raise the environmental credentials of the product.
Claisen type Condensation of Methyl Ketones with Carbimidothioates: A New Gateway for the Synthesis of β‐Enaminones
Authors: Swaroop Toreshettahally R. , Rangappa Kanchugarakoppal S. , Torun Lokman 
Published: January 2021

AbstractCarbimidothioates are synthesized by the reaction of Grignard reagents or heteroaryl lithium compounds with arylisothiocyanates followed by treatment with methyl iodide. Further, application of these intermediates in the synthesis of β‐enaminones by their condensation with methyl ketones in the presence of sodium hydride in DMF is reported. This method offers a new gateway for the synthesis of β‐enaminones, which are important building blocks in synthetic organic chemistry.
Influence of Calcination on Mesoporous Mn1Zr0.5Oy Solid Solution in Oxidative Coupling Catalysis for Benzylideneaniline Formation
Authors: Wu Shipeng , Wei Kun , Fang Wenhao 
Published: January 2021

AbstractA mesoporous Mn1Zr0.5Oy solid solution is prepared with a template‐free co‐precipitation method and is used as an efficient heterogeneous catalyst for oxidative coupling of benzyl alcohol and aniline in the absence of base under mild conditions. XRD, XPS, N2 physisorption, H2‐TPR, O2‐TPD, NH3‐TPD and CO2‐TPD were used to study the influence of calcination temperature on the structure, redox properties, acidity‐basicity, as well as the catalytic behaviors of the Mn1Zr0.5Oy catalyst. The results show that the optimal catalyst calcined at 400 °C displays the highest specific surface area (228 m2 g−1), highest fraction of unsaturated Mn3+ ions (45.4 %) and reactive Osurf. species (52.5 %), and the highest acidity (1.06 mmol g−1) and basicity (0.48 mmol g−1). Thereby, an enhanced benzylideneaniline formation (5.50 mmol gcat−1 h−1) based on a 99 % yield is obtained at 80 °C under air atmosphere. This is one of the top results ever reported for all the Mn‐based catalysts. The structure‐activity relation is finally discussed.
3D Printing of Supramolecular Polymer Hydrogels with Hierarchical Structure
Authors: Sather Nicholas A. , Sai Hiroaki , Sasselli Ivan R. , Sato Kohei , Ji Wei , Synatschke Christopher V. , Zambrotta Ryan T. , Edelbrock John F. , Kohlmeyer Ryan R. , Hardin James O. , Berrigan John Daniel , Durstock Michael F. , Mirau Peter , Stupp Samuel I. 
Published: January 2021

AbstractLiquid crystalline hydrogels are an attractive class of soft materials to direct charge transport, mechanical actuation, and cell migration. When such systems contain supramolecular polymers, it is possible in principle to easily shear align nanoscale structures and create bulk anisotropic properties. However, reproducibly fabricating and patterning aligned supramolecular domains in 3D hydrogels remains a challenge using conventional fabrication techniques. Here, a method is reported for 3D printing of ionically crosslinked liquid crystalline hydrogels from aqueous supramolecular polymer inks. Using a combination of experimental techniques and molecular dynamics simulations, it is found that pH and salt concentration govern intermolecular interactions among the self‐assembled structures where lower charge densities on the supramolecular polymers and higher charge screening from the electrolyte result in higher viscosity inks. Enhanced hierarchical interactions among assemblies in high viscosity inks increase the printability and ultimately lead to greater nanoscale alignment in extruded macroscopic filaments when using small nozzle diameters and fast print speeds. The use of this approach is demonstrated to create materials with anisotropic ionic and electronic charge transport as well as scaffolds that trigger the macroscopic alignment of cells due to the synergy of supramolecular self‐assembly and additive manufacturing.
Chemically Propelled Nano and Micromotors in the Body: Quo Vadis?
Authors: Somasundar Ambika , Sen Ayusman 
Published: January 2021

AbstractThe active delivery of drugs to disease sites in response to specific biomarkers is a holy grail in theranostics. If successful, it would greatly diminish the therapeutic dosage and reduce collateral cytotoxicity. In this context, the development of nano and micromotors that are able to harvest local energy to move directionally is an important breakthrough. However, serious hurdles remain before such active systems can be employed in vivo in therapeutic applications. Such motors and their energy sources must be safe and biocompatible, they should be able to move through complex body fluids, and have the ability to reach specific cellular targets. Given the complexity in the design and deployment of nano and micromotors, it is also critically important to show that they are significantly superior to inactive “smart” nanoparticles in theranostics. Furthermore, receiving regulatory approval requires the ability to scale‐up the production of nano and micromotors with uniformity in structure, function, and activity. In this essay, the limitations of the current nano and micromotors and the issues that need to be resolved before such motors are likely to find theranostic applications are discussed.
Suppressing the liquid product crossover in electrochemical CO2 reduction
Authors: Wang Ning , Miao Rui Kai , Lee Geonhui , Vomiero Alberto , Sinton David , Ip Alexander H. , Liang Hongyan , Sargent Edward H. 
Published: January 2021

AbstractCoupling electrochemical CO2 reduction (CO2R) with a renewable energy source to create high‐value fuels and chemicals is a promising strategy in moving toward a sustainable global energy economy. CO2R liquid products, such as formate, acetate, ethanol, and propanol, offer high volumetric energy density and are more easily stored and transported than their gaseous counterparts. However, a significant amount (~30%) of liquid products from electrochemical CO2R in a flow cell reactor cross the ion exchange membrane, leading to the substantial loss of system‐level Faradaic efficiency. This severe crossover of the liquid product has—until now—received limited attention. Here, we review promising methods to suppress liquid product crossover, including the use of bipolar membranes, solid‐state electrolytes, and cation‐exchange membranes‐based acidic CO2R systems. We then outline the remaining challenges and future prospects for the production of concentrated liquid products from CO2.
Metal Halide Perovskite/2D Material Heterostructures: Syntheses and Applications
Authors: Zhang Zhipeng , Wang Sisi , Liu Xinfeng , Chen Yonghua , Su Chenliang , Tang Zikang , Li Ying , Xing Guichuan 
Published: January 2021

AbstractThe past decade has witnessed the great success achieved by metal halide perovskites (MHPs) in photovoltaic and related fields. However, challenges still remain in further improving their performance, as well as, settling the stability issue for future commercialization. Recently, MHP/2D material heterostructures that combining MHPs with the low‐cost and solution‐processable 2D materials have demonstrated unprecedented improvement in both performance and stability due to the distinctive features at hetero‐interface. The diverse fabrication techniques of MHPs and 2D materials allow them to be assembled as heterostructures with different configurations in a variety of ways. Moreover, the large families of MHPs and 2D materials provide the opportunity for the rational design and modification on compositions and functionalities of MHP/2D materials heterostructures. Herein, a comprehensive review of MHP/2D material heterostructures from syntheses to applications is presented. First, various fabrication techniques for MHP/2D material heterostructures are introduced by classifying them into solid‐state methods and solution‐processed methods. Then the applications of MHP/2D heterostructures in various fields including photodetectors, solar cells, and photocatalysis are summarized in detail. Finally, current challenges for the development of MHP/2D material heterostructures are highlighted, and future opportunities for the advancements in this research field are also provided.
Analysis of an individual‐based influenza epidemic model using random forest metamodels and adaptive sequential sampling
Authors: Edali Mert , Yücel Gönenç 
Published: January 2021

AbstractThis study proposes a three‐step procedure for the analysis of input–response relationships of dynamic models, which enables the analyst to develop a better understanding about the dynamics of the system. The main building block of the procedure is a random forest metamodel capturing the input–output relationships. We utilize an active learning approach as the second step to improve the accuracy of the metamodel. In the last step, we develop a novel way to present the information captured by the metamodel as a set of intelligible IF–THEN rules. For illustration, we use the FluTE model, which is an individual‐based influenza epidemic model. We observe that the number of daily applicable vaccines determines the success of an intervention strategy the most. Another critical observation is that when the daily available vaccines are constrained, nonpharmaceutical strategies should be incorporated to reduce the extent of the outbreak.