bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanocrystallite–liquid phase transition in porous matrices with chemically functionalized surfaces
Authors: Lazarenko Maxim M. , Alekseev Alexander N. , Alekseev Sergei A. , Zabashta Yuriy F. , Grabovskii Yurii E. , Hnatiuk Kateryna I. , Dinzhos Roman V. , Simeonov Marin S. , Kolesnichenko Valeriy G. , Ushcats Michael V. , Bulavin Leonid A.
Published: October 2019

Melting temperatures of 1-octadecene confined in the pores of chemically functionalized silica gels vs. the ratio of surface area to pore volume.
Binding enabled catalytic activation of SO2 by copper koneramine complexes under ambient conditions
Authors: Chahal Manoj , Raje Sakthi , Kotana Gopichand , Angamuthu Raja
Published: October 2019

Reported is a simple and sustainable strategy to catalytically convert SO2 gas into sulfate under ambient conditions utilizing ferrocene (SO2 + 2Fc + aerial O2 → Fc2SO4) and aerial oxygen.
An integrated approach between neutron diffraction and elemental imaging through neutron resonance transmission imaging: preliminary results on Chinese bimetallic sword fragments
Authors: Fedrigo Anna , Raspino Davide , Grazzi Francesco , Scherillo Antonella
Published: October 2019

Neutron diffraction and neutron resonance transmission imaging are applied for the material characterization of two bimetallic sword fragments from ancient China, to highlight the presence and distribution of phases and elements in the objects.
Which DFT levels of theory are appropriate in predicting the prolyl cis–trans isomerization in solution?
Authors: Park Hae Sook , Kang Young Kee
Published: October 2019

DFTs were assessed for the conformational preferences of the peptides containing Pro and its derivatives in chloroform and water.
Development of a potential LPG sensor based on a PANI–Co3O4 nanocomposite that functions at room temperature
Authors: Singh Neetu , Singh Prabhat Kumar , Singh Mridula , Gangopadhyay Debraj , Singh Saurabh Kumar , Tandon Poonam
Published: October 2019

Nanostructured Co3O4 was synthesized by a sol–gel technique while 30% & 40% Co3O4–PANI (polyaniline) nanocomposites were successfully prepared employing an in situ polymerization technique.
Study on the growth and morphology evolution of titanium oxide clusters in molten iron with molecular dynamics simulation
Authors: Yang Likun , Zhang Wei , He Liang , Li Huigai , Zheng Shaobo
Published: October 2019

The aggregation and growth of titanium oxygen clusters before nucleation were simulated by molecular dynamics.
One-pot syntheses of irida-polycyclic aromatic hydrocarbons
Authors: Hu Yu Xuan , Zhang Jing , Wang Xiaoyan , Lu Zhengyu , Zhang Fangfang , Yang Xiaofei , Ma Zhihua , Yin Jun , Xia Haiping , Liu Sheng Hua
Published: October 2019

A series of new irida-policyclic aromatic hydrocarbons were prepared using a one-pot method, and their photophysical properties were explored.
Preparation of colloidal molecules with temperature-tunable interactions from oppositely charged microgel spheres
Authors: Månsson Linda K. , de Wild Tym , Peng Feifei , Holm Stefan H. , Tegenfeldt Jonas O. , Schurtenberger Peter
Published: October 2019

Oppositely charged, soft, temperature-responsive PNIPAM microgels are used to assemble core–satellite-type colloidal molecules, thereby enabling convenientin situtuning of size, volume fraction and inter-particle interactions with temperature.
Correction: Design rules for encapsulating proteins into complex coacervates
Authors: Blocher McTigue Whitney C. , Perry Sarah L.
Published: October 2019

Correction for ‘Design rules for encapsulating proteins into complex coacervates’ by Whitney C. Blocher McTigue et al., Soft Matter, 2019, 15, 3089–3103.
Phosphorylation of human placental aromataseCYP19A1
Authors: Ghosh Debashis , Egbuta Chinaza , Kanyo Jean E. , Lam TuKiet T.
Published: October 2019

Aromatase CYP19A1 catalyzes the synthesis of estrogens in endocrine, reproductive and central nervous systems. Higher levels of 17β-estradiol (E2) are associated with malignancies and diseases of the breast, ovary and endometrium, while low E2 levels increase the risk for osteoporosis, cardiovascular diseases and cognitive disorders. E2, the transcriptional activator of the estrogen receptors, is also known to be involved in non-genomic signaling as a neurotransmitter/neuromodulator, with recent evidence for rapid estrogen synthesis (RES) within the synaptic terminal. Although regulation of brain aromatase activity by phosphorylation/dephosphorylation has been suggested, it remains obscure in the endocrine and reproductive systems. RES and overabundance of estrogens could stimulate the genomic and non-genomic signaling pathways, and genotoxic effects of estrogen metabolites. Here, by utilizing biochemical, cellular, mass spectrometric, and structural data we unequivocally demonstrate phosphorylation of human placental aromatase and regulation of its activity. We report that human aromatase has multiple phosphorylation sites, some of which are consistently detectable. Phosphorylation of the residue Y361 at the reductase-coupling interface significantly elevates aromatase activity. Other sites include the active site residue S478 and several at the membrane interface. We present the evidence that two histidine residues are phosphorylated. Furthermore, oxidation of two proline residues near the active site may have implications in regulation. Taken together, the results demonstrate that aromatase activity is regulated by phosphorylation and possibly other post-translational modifications. Protein level regulation of aromatase activity not only represents a paradigm shift in estrogen-mediated biology, it could also explain unresolved clinical questions such as aromatase inhibitor resistance.
Radial-velocity jitter of stars as a function of observational timescale and stellar age
Authors: Brems Stefan S. , Kürster Martin , Trifonov Trifon , Reffert Sabine , Quirrenbach Andreas
Published: October 2019

Context.Stars show various amounts of radial-velocity (RV) jitter due to varying stellar activity levels. The typical amount of RV jitter as a function of stellar age and observational timescale has not yet been systematically quantified, although it is often larger than the instrumental precision of modern high-resolution spectrographs used for Doppler planet detection and characterization.

Aims.We aim to empirically determine the intrinsic stellar RV variation for mostly G and K dwarf stars on different timescales and for different stellar ages independently of stellar models. We also focus on young stars (≲30 Myr), where the RV variation is known to be large.

Methods.We use archival FEROS and HARPS RV data of stars which were observed at least 30 times spread over at least two years. We then apply the pooled variance (PV) technique to these data sets to identify the periods and amplitudes of underlying, quasiperiodic signals. We show that the PV is a powerful tool to identify quasiperiodic signals in highly irregularly sampled data sets.

Results.We derive activity-lag functions for 20 putative single stars, where lag is the timescale on which the stellar jitter is measured. Since the ages of all stars are known, we also use this to formulate an activity–age–lag relation which can be used to predict the expected RV jitter of a star given its age and the timescale to be probed. The maximum RV jitter on timescales of decades decreases from over 500 m s−1for 5 Myr-old stars to 2.3 m s−1for stars with ages of around 5 Gyr. The decrease in RV jitter when considering a timescale of only 1 d instead of 1 yr is smaller by roughly a factor of 4 for stars with an age of about 5 Myr, and a factor of 1.5 for stars with an age of 5 Gyr. The rate at which the RV jitter increases with lag strongly depends on stellar age and reaches 99% of the maximum RV jitter over a timescale of a few days for stars that are a few million years old, up to presumably decades or longer for stars with an age of a few gigayears.
Testing magnetohydrostatic extrapolation with radiative MHD simulation of a solar flare
Authors: Zhu X. , Wiegelmann T.
Published: October 2019

Context. On the sun, the magnetic field vector is measured routinely solely in the photosphere. By using these photospheric measurements as a boundary condition, we developed magnetohydrostatic (MHS) extrapolation to model the solar atmosphere. The model makes assumptions about the relative importance of magnetic and non-magnetic forces. While the solar corona is force-free, this is not the case with regard to the photosphere and chromosphere.

Aims. The model has previously been tested with an exact equilibria. Here we present a more challenging and more realistic test of our model with the radiative magnetohydrodynamic simulation of a solar flare.

Methods. By using the optimization method, the MHS model computes the magnetic field, plasma pressure and density self-consistently. The nonlinear force-free field (NLFFF) and gravity-stratified atmosphere along the field line are assumed as the initial conditions for optimization.

Results. Compared with the NLFFF, the MHS model provides an improved magnetic field not only in magnitude and direction, but also in magnetic connectivity. In addition, the MHS model is capable of recovering the main structure of plasma in the photosphere and chromosphere.
Predicting the global far-infrared SED of galaxies via machine learning techniques
Authors: Dobbels W. , Baes M. , Viaene S. , Bianchi S. , Davies J. I. , Casasola V. , Clark C. J. R. , Fritz J. , Galametz M. , Galliano F. , Mosenkov A. , Nersesian A. , Trčka A.
Published: October 2019

Context. Dust plays an important role in shaping a galaxy’s spectral energy distribution (SED). It absorbs ultraviolet (UV) to near-infrared radiation and re-emits this energy in the far-infrared (FIR). The FIR is essential to understand dust in galaxies. However, deep FIR observations require a space mission, none of which are still active today.

Aims. We aim to infer the FIR emission across six Herschel bands, along with dust luminosity, mass, and effective temperature, based on the available UV to mid-infrared (MIR) observations. We also want to estimate the uncertainties of these predictions, compare our method to energy balance SED fitting, and determine possible limitations of the model.

Methods. We propose a machine learning framework to predict the FIR fluxes from 14 UV–MIR broadband fluxes. We used a low redshift sample by combining DustPedia and H-ATLAS, and extracted Bayesian flux posteriors through SED fitting. We trained shallow neural networks to predict the far-infrared fluxes, uncertainties, and dust properties. We evaluated them on a test set using a root mean square error (RMSE) in log-space.

Results. Our results (RMSE = 0.19 dex) significantly outperform UV–MIR energy balance SED fitting (RMSE = 0.38 dex), and are inherently unbiased. We can identify when the predictions are off, for example when the input has large uncertainties on WISE 22 μm, or when the input does not resemble the training set.

Conclusions. The galaxies for which we have UV–FIR observations can be used as a blueprint for galaxies that lack FIR data. This results in a “virtual FIR telescope”, which can be applied to large optical-MIR galaxy samples. This helps bridge the gap until the next FIR mission.
Statistical methods for monitoring the operation of cathodic protection stations
Authors: Gerasina Tatiana , Zarubin Alexey , Zarubina Oxana
Published: October 2019

This article is a result of the research on the methods to monitor the operation of cathodic protection stations. This study presents the experimental data analysis of the work of cathodic protection stations was carried out by the transportation company with measurements for two quarters. Statistical analysis realized on the basis of Shewhart control charts.
Investigation of the corrosion process and destruction of metals by using acoustodamage method
Authors: Tretyakov Dmitry , Belyaev Alexander , Galyautdinova Aliya , Polyanskiy Vladimir , Strekalovskaya Darya
Published: October 2019

The paper presents the results of investigation of acoustic anisotropy in industrial alloy made of steel 14HGNDC after hydrogen-induced cracking (HIC) tests according to the standard NACE TM0284-2003. It was found that location and parameters of corrosion cracks with size about 20 microns can be determined by distribution and value of acoustic anisotropy. A quantitative relationship between value of acoustic anisotropy and size of corrosion cracks in the range from 60 to 6600 microns was established. The obtained results have a great importance for improving methods of hydrogen-induced cracking tests and for non-destructive testing of brittle destruction of structures in oil and gas industry by using the acoustodamage method.
An innovative laboratory characterization: hydrogen interaction with X60 pipeline steel
Authors: Valentini Renzo , Gabetta Giovanna , Bacchi Linda , Corsinovi Serena , Villa Michele
Published: October 2019

Corrosion is evaluated to be one of the most important cause for pipeline failures. Given the serious consequences of these events in terms of human safety, environmental preservation and cost saving, it is evident that on-field corrosion control could have a fundamental role. The aim of the present work was to meet this need with preliminary feasibility study to develop a test procedure, characterized at the same time by non-invasive approach and scientific rigor, to evaluate the possibility of on-line monitoring and assess the integrity of a pipeline during its operation. The experimental campaign was performed on a HSLA Steel X60, characterized by a ferritic microstructure with fine grains and ultimate tensile strength equal to 520MPa. The hydrogen interaction with steel was investigated by means of an advanced equipment based on an innovative high sensitivity hydrogen gas sensor. The following types of investigations were carried out [1]:

- Various permeation tests were performed with reference to EN ISO 17081:2014 increasing test temperature from 10°C to 60°C.

- Afterwards a series of Hydrogen Induced Cracking nucleation tests was performed with reference to ASTM STP 692:0.

- Finally, permeation concept was applied in an innovative way to Hydrogen Induced Cracking nucleation phenomena.
Carboline’s systems approach to the maintenance of coating systems for steel structures in the oil and gas industry
Authors: Konovalov Gennadiy
Published: October 2019

The article discusses options for optimal repair systems with several advantages compared with competitive solutions in the market of protective coatings. The proposed materials have a high tolerance to the degree of surface preparation, compatibility with old protective systems, as well as low levels of internal stresses arising in the repair layer of coating, which significantly reduces the risk of pulling off the old protective coatings after repair.
The effect of magnetic treatment on the effectiveness of inhibition in oilfields
Authors: Golubev I.A. , Laptev A.B. , Alekseeva E.L , Shaposhnikov N.O. , Povyshev A.M. , Kurakin M.K.
Published: October 2019

The article considers the possibility of increasing the efficiency of chemical reagents by treating inhibited solutions with a magnetic field. It is shown that a various method for generating the magnetic field has a different effect (Some positive some negative). The best results can be achieved with anti-scale magnetic treatment using permanent magnets. Modified inhibitors (after magnetic treatment) have enhanced protective effectby their adsorption capacity with respect to metal increases.
Characterization of non-metallic inclusions in corrosion -resistance nickel - based EP718 and 718 alloys by using electrolytic extraction method
Authors: Karasev Andrey , Alekseeva Ekaterina , Lukianov Aleksey , Jönsson Pär G.
Published: October 2019

It is known that non-metallic inclusions (NMI) that are formed during steel production and heat treatment can significantly affect the properties of final steel products. Therefore, it is very important to be able to determine the content of harmful NMI in steels. Nickel-based alloys are widely used in the oil and gas recovery industry, due to a good combination of strength and corrosion properties. Earlier studies have shown that the corrosion properties in immersion test and electrochemical tests for Ni-based EP718 alloys are slightly lower than that for 718 alloys. The focus in this study was the influence of different NMI on the corrosion resistance of these alloys. The characteristics of inclusions (such as size, morphology, and chemical composition) were analysed by using the electrolytic extraction method followed by three-dimensional investigations using SEM in combination with EDS. It was found that some non-metallic inclusions in EP718 alloys significantly reduce its corrosion resistance. It was also shown that a primary dissolution of the metal matrix occurs around certain inclusions during electrolytic extraction. Based on obtained results, the corrosion active non-metallic inclusions can be determined in these Nickel-base alloys and some recommendations for optimization of their production technology can be formulated.
Materials science aspects of stress corrosion cracking of Russian pipelines
Authors: Kantor M.M. , Sudin V.V. , Solntsev K.A.
Published: October 2019

The work describes the features of stress corrosion cracking (SCC) on Russian gas pipelines. The influence of metal parameters of pipelines on the propagation of SCC is described. The main diagnostic features of SCC used for identification of this type of fracture, the stages of crack growth and the effect of microstructural metal parameters on their propagation are described. Accounting methods for main features crack initiation and growth in order to improve the resistance of the main pipelines metal to SCC are proposed
Approaches to the selection of the most effective corrosion inhibitors in JSC Gazprom Neft
Authors: Anisa Kunakova , Liniza Sayfutdinova , Vladimir Yampurov , Alexandra Gogoleva
Published: October 2019

The article considers an approach to the selection of reagents for protecting pipelines from corrosion. The report gives a list of required laboratory tests. This allows to identify effective corrosion inhibitors for their further field tests. The implementation of the approach driving tangible buisness benefits.
The Impacts of Power Infrastructure Development in the Socio-Economic Situations in Sub-Sahara Africa
Authors: Ntebo Ngcobo , Mathe Kasenge , Oikelomen Ayorinde Emmanuel
Published: October 2019

Infrastructural development is fundamental in nationʼs economic growth and development. Power infrastructure is imperative for nation building and helps create employment and improved the well-being of its citizens. This research paper identifies the impact of power infrastructure development on the economic growth in sub-Saharan Africa (SSA). The study adopted a quantitative research approach with data gathered from the respondents within power infrastructure development in the region. Information gathered were analysed using mean item score, standard deviation and factor analysis. The findings revealed the impact of power development on the economic benefit in SSA to be wealth creation, boost in citizensʼ income, health care improvement, improved educational systems were seen as the direct impact of infrastructure development on the economic situation in sub-Sahara Africa. Since the lack of infrastructural facilities of an economy can lead to various setbacks in the nationʼs economic development, it thereby requires adequate participations by stakeholders to deliver sustainable power infrastructure development in the society. The study power infrastructure development can contribute to regional and national growth, urbanization challenges, and improvement in the environmental through the provision of clean energy which foster social and economic inclusion.
Recent Advances in the Synthesis of Acridines and Phenazines
Authors: Xiao Yan , Hu Weiming , Sun Song , Yu Jin-Tao , Cheng Jiang
Published: October 2019

Acridines and phenazines are common motifs in bioactive compounds and natural products. Many excellent works on the synthesis of these skeletons starting from diaryliodonium salts, benzaldehydes, anthranils, azobenzenes, and nitrosobenzenes have been reported. In this overview, we highlight several recent elegant works on the synthesis of acridines and phenazines.

1 Introduction

2 Synthesis of Acridines

3 Synthesis of Phenazines

4 Conclusion
Synthesis of New γ-Lactams with gem-Difluorinated Side Chains
Authors: Soulieman Ali , Gouault Nicolas , Roisnel Thierry , Justaud Frédéric , Boustie Joël , Grée René , Hachem Ali
Published: October 2019

A short and efficient approach has been designed for the synthesis of new γ-lactams that feature gem-difluorinated side-chains in position 4. The key steps involve 1,4-addition of nitroalkane anions on electrophilic gem-difluoroalkenes, followed by a cascade nitro reduction–heterocyclization. This flexible strategy also allows easy introduction of substituents in positions 3 or 5.
Benefitting from immigration: The value of immigrants’ country knowledge for firm internationalization
Authors: Kunczer Vera , Lindner Thomas , Puck Jonas
Published: October 2019

Migrants are able to provide firms with knowledge about their country of origin. This can become a valuable source of knowledge for firms in the process of internationalization. Relating to a Knowledge-Based-View perspective, this paper explains how the resource commitment of firms to foreign countries is contingent on immigration from those countries: Immigrants’ country knowledge reduces uncertainty and makes the governance of foreign operations more efficient. Moreover, this paper connects the relevance of knowledge for firm internationalization to institutional characteristics in immigrants’ home and host countries, both of which policymakers can shape. We test predictions on more than 13,000 observations over a 14-year period (2003–2016). The paper identifies economically significant contingencies of a positive effect of immigration, which are robust to changes in model specification, measurement, and sampling. The results indicate how immigration can shape firms’ investments abroad and have implications for developing policy as well as international business theory.
Nonvolatile memory based on redox-active ruthenium molecular monolayers
Authors: Jiang Kai , Pookpanratana Sujitra J. , Ren Tong , Natoli Sean N. , Sperling Brent A. , Robertson Joseph , Richter Curt A. , Yu Sheng , Li Qiliang
Published: October 2019

A monolayer of diruthenium molecules was self-assembled onto the silicon oxide surface in a semiconductor capacitor structure with a “click” reaction for nonvolatile memory applications. The attachment of the active molecular monolayer was verified by x-ray photoelectron spectroscopy. The prototypical capacitor memory devices in this work employed a metal/oxide/molecule/oxide/Si structure. With the intrinsic redox-active charge-storage properties of diruthenium molecules, these capacitor memory devices exhibited fast Program and Erase speed, excellent endurance performance with negligible degradation of the memory window after 105 program/erase cycles, and very good 10-year memory retention. These experimental results indicate that the redox-active ruthenium molecular memory is very promising for use in nonvolatile memory applications.
A simple method to characterize high rate twin boundary kinetics in Ni-Mn-Ga
Authors: Karki Bibek , Behar Yotam , Harel Itai , Caplan Eitan , Sabbag Arik , Shilo Doron , Mullner Peter , Faran Eilon
Published: October 2019

Experimental characterization of twin boundary kinetics is essential to systematically test and reproduce the actuation properties of Magnetic Shape Memory (MSM) elements at high rates. Here, we present a simple, nondestructive, experimental method to quantify the dynamic response of an MSM crystal and extract the major material properties that govern its kinetics. The tested sample is subjected to a mechanical pulse that is produced by a simple off-the-shelf solenoid. The mechanical pulse leads to actuation of the tested MSM Ni–Mn–Ga single crystal within 10 ms, during which the twin boundary velocity varies between zero and 2 m/s. The displacement and force in the MSM crystal are measured simultaneously using an optical sensor and a miniature force sensor, respectively. The data captured during a single loading experiment allow plotting a dynamic stress-strain curve as well as a kinetic relation that characterizes the macroscopic response of the crystal. In particular, the obtained kinetic relation enables the extraction of the transition driving force between slow (thermally activated) and fast (athermal) twin boundary motions. This transition driving force is a key material property that governs fast actuation capabilities of MSM elements. The macroscopic behavior of the sample is correlated with the motion of individual twin boundaries within the crystal by adding high speed microscopy to the experimental setup. This allows simultaneous high-rate tracking of individual twinning interfaces in Ni–Mn–Ga.
High temperature piezoelectric properties of flux-grown α-GeO2 single crystal
Authors: Papet Philippe , Bah Micka , Haidoux Abel , Ruffle Benoit , Menaert Bertrand , Peña Alexandra , Debray Jérôme , Armand Pascale
Published: October 2019

The temperature dependence of the piezoelectric properties of trigonal α-GeO2 single crystals obtained by the high-temperature flux method was measured by the resonance technique of the electrical impedance in the 20 °C–600 °C range. To approach the values of the two independent piezoelectric coefficients d11 and d14, we first measured as a function of temperature the elastic coefficients S11, S14, and S66 and the dielectric permittivity ε11, which are involved in the coupling coefficient k of both the thickness shear mode and the transverse mode. A Y-cut plate with a simple +45° rotation [(YXtwl) +45°/0°/0°] was used to measure the coupling coefficient of the thickness shear mode, and two X-turned plates [(XYtwl) +45°/0°/0° and (XYtwl) −45°/0°/0°] were prepared to characterize the coupling coefficient of two transverse modes. From the whole experimental measurements, the piezoelectric coefficients of α-GeO2 were calculated up to 600 °C. They show that this crystal is one of the most efficient in regard to the α-quartz-like family at room temperature and that its thermal comportment retains large piezoelectric properties up to 600 °C.
A generalized minimal residual method-based immersed boundary-lattice Boltzmann flux solver coupled with finite element method for non-linear fluid-structure interaction problems
Authors: Wang Y. , Shu C. , Wang T. G. , Valdivia y Alvarado P.
Published: October 2019

A generalized minimal residual method (GMRES) based immersed boundary-lattice Boltzmann flux solver (IB-LBFS) coupled with the finite element method (FEM) is presented in this paper for nonlinear fluid-structure interaction (FSI) problems. This approach effectively combines LBFS for the simulation of the flow field, the total Lagrangian FEM for the evaluation of nonlinear structural deformations, and the immersed boundary method (IBM) for the exchange of information on the fluid-solid interface and implementation of boundary conditions. Both the multidirect forcing and the implicit IBM are considered to examine their effects on numerical accuracy and efficiency. Through numerical simulations on flow past a cylinder, it is shown that the implicit IBM with the GMRES for the linear equation system is more efficient and accurate, which justify the conventional misunderstanding that implicit IBM is always less efficient than explicit methods. Numerical simulations on the lid-driven cavity flow in an inclined cavity, incompressible flows of a uniformly accelerated vertical plate, and the flow induced vibrations of a beam attached behind a cylinder in a channel are also successfully carried out and the obtained results are in good agreement with the published data, which verify the reliability and flexibility of the proposed solver for simulating nonlinear FSI problems. After that, the external flows past two hyperelastic cylinder-beam structures at the Reynolds number of 40–300 are studied and three different modes of static, linear, and nonlinear deformations of the beam are obtained, demonstrating its capability of simulating flows with nonlinear FSI problems with multiple deformable objects.
Robust and accurate hybrid random-phase-approximation methods
Authors: Thierbach Adrian , Schmidtel Daniel , Görling Andreas
Published: October 2019

A fully self-consistent hybrid dRPA (direct random phase approximation) method, named sc-H[γ]dRPA, is presented with γ = 1/3. The exchange potential of the new method contains a fraction γ of nonlocal Hartree-Fock-like exchange besides the exact local Kohn-Sham (KS) exchange potential. The sc-H[γ]dRPA method, in contrast to a straightforward self-consistent dRPA method within the KS formalism, does not suffer from convergence problems for systems with small eigenvalue gaps. Moreover, the sc-H[γ]dRPA method yields distinctively more accurate reaction, isomerization, and transition state energies than other dRPA approaches, e.g., the frequently used non-self-consistent dRPA method using orbitals and eigenvalues from a KS calculation with the exchange-correlation potential of Perdew, Burke, and Ernzerhof (PBE). The sc-H[γ]dRPA method outperforms second-order Møller-Plesset perturbation theory and coupled cluster singles doubles methods while exhibiting a more favorable scaling of computational costs with system size. A value of γ = 1/3 is shown to be a good choice also for a dRPA@PBE[γ] method, which is a non-self-consistent dRPA method using orbitals and eigenvalues from the hybrid PBE0 method with an admixture of γ = 1/3 of exact exchange instead of the 25% of the PBE0 functional. The dRPA@PBE[γ] method yields reaction, isomerization, and transition state energies that are as good as the sc-H[γ]dRPA ones but is computationally simpler and more efficient because it does not require the self-consistent construction of the dRPA correlation potential. The direct sc-H[γ]dRPA, on the other hand, in contrast to all standard density-functional methods, yields qualitatively correct correlation potentials.
Chemically accurate excitation energies with small basis sets
Authors: Giner Emmanuel , Scemama Anthony , Toulouse Julien , Loos Pierre-François
Published: October 2019

By combining extrapolated selected configuration interaction (sCI) energies obtained with the Configuration Interaction using a Perturbative Selection made Iteratively algorithm with the recently proposed short-range density-functional correction for basis-set incompleteness [E. Giner et al., J. Chem. Phys. 149, 194301 (2018)], we show that one can get chemically accurate vertical and adiabatic excitation energies with, typically, augmented double-ζ basis sets. We illustrate the present approach on various types of excited states (valence, Rydberg, and double excitations) in several small organic molecules (methylene, water, ammonia, carbon dimer, and ethylene). The present study clearly evidences that special care has to be taken with very diffuse excited states where the present correction does not catch the radial incompleteness of the one-electron basis set.
Experimental demonstration of free electron maser operation in the regime of non-resonant trapping
Authors: Kaminsky A. K. , Sedykh S. N. , Bandurkin I. V. , Golubev I. I. , Golubykh S. M. , Kozlov A. P. , Peskov N. Yu. , Savilov A. V. , Sidorov A. I.
Published: October 2019

The regime of nonresonant trapping aimed at improving the operation of the amplifying scheme of free electron devices has been developed and experimentally demonstrated in the Ka-band. In this regime, the wiggler is profiled in such a way that the electron beam is out of resonance with the operating wave at the beginning of the wiggler, and different electron fractions gradually get into synchronism as the wiggler's period decreases. According to the simulations, such “nonresonant” trapping provides higher efficiency, a broader amplification band, and lower sensitivity to the beam quality as compared to conventional regimes of interaction. The conclusions of the theoretical analysis are confirmed by the results of joint experiments between the Joint Institute for Nuclear Research and the Institute of Applied Physics of the Russian Academy of Sciences, in which a free-electron maser utilizing this regime was implemented: Using a set of kilowatt magnetrons with frequencies in the range from 30 to 36 GHz, an output power of up to 25–28 MW with a gain of up to 36–37 dB was demonstrated. This makes the investigated regime attractive for shorter wavelength designs of free-electron devices whose efficiency is strongly affected by the electron beam quality.
Reduced dislocation density and residual tension in AlN grown on SiC by metalorganic chemical vapor deposition
Authors: Zollner Christian J. , Almogbel Abdullah , Yao Yifan , SaifAddin Burhan K. , Wu Feng , Iza Michael , DenBaars Steven P. , Speck James S. , Nakamura Shuji
Published: October 2019

Crack-free AlN films with threading dislocation density (TDD) below 109 cm−2 are needed for deep-UV optoelectronics. This is typically achieved using pulsed lateral overgrowth or very thick buffer layers (>10 μm), a costly and time-consuming approach. A method for conventional metalorganic chemical vapor deposition growth of AlN/SiC films below 3 μm with greatly improved quality is presented. Focusing on substrate pretreatment before growth, we reduce average film stress from 0.9 GPa (tension) to −1.1 GPa (compression) and eliminate cracking. Next, with optimized growth conditions during initial deposition, AlN films with x-ray rocking curve widths of 123 arc-sec (0002) and 304 arc-sec (202¯1) are developed, and TDD is confirmed via plan view transmission electron microscopy (TEM) to be 2 × 108 cm−2. Film stress measurements including x-ray 2θ-ω, reciprocal space mapping, and curvature depict compressively stressed growth of AlN on 4H-SiC due to lattice mismatch. The thermal expansion coefficient mismatch between AlN and SiC is measured to be Δα=αAlN−αSiC=1.13×10−6 °C−1 and is found to be constant between room temperature and 1400 °C. TEM confirms the existence of dense misfit dislocation (MD) networks consistent with MD formation near SiC step edges and low MD density regions attributed to nearly coherent AlN growth on SiC terraces. These low-TDD, crack-free AlN/SiC buffers provide a platform for deep-UV optoelectronics and ultrawide bandgap electronics.
Electrified cone formation in perfectly conducting viscous liquids: Self-similar growth irrespective of Reynolds number
Authors: Albertson Theodore G. , Troian Sandra M.
Published: October 2019

Above a critical field strength, the free surface of an electrified, perfectly conducting viscous liquid, such as a liquid metal, is known to develop an accelerating protrusion resembling a cusp with a conic tip. Field self-enhancement from tip sharpening is reported to generate divergent power law growth in finite time of the forces acting in that region. Previous studies have established that tip sharpening proceeds via a self-similar process in two distinguished limits—the Stokes regime and the inviscid regime. Using finite element simulations to track the shape and forces acting at the tip of an electrified protrusion in a perfectly conducting Newtonian liquid, we demonstrate that the conic tip always undergoes self-similar growth irrespective of the Reynolds number. The blowup exponents at the conic apex for all terms in the Navier-Stokes equation and the normal stress boundary condition at the moving interface reveal the dominant forces at play as the Reynolds number increases. Rescaling of the tip shape by the power law representing the divergence in capillary stress at the apex yields an excellent collapse onto a universal cone shape with an interior half-angle dependent on the Maxwell stress. The rapid acceleration of the liquid interface also generates a thin interfacial boundary layer characterized by a significant rate of strain. Additional details of the modeled flow, applicable to cone growth in systems such as liquid metal ion sources, help dispel prevailing misconceptions that dynamic cones resemble conventional Taylor cones or that viscous stresses at a finite Reynolds number can be neglected.
Near-infrared optical properties and proposed phase-change usefulness of transition metal disulfides
Authors: Singh Akshay , Li Yifei , Fodor Balint , Makai Laszlo , Zhou Jian , Xu Haowei , Akey Austin , Li Ju , Jaramillo R.
Published: October 2019

The development of photonic integrated circuits would benefit from a wider selection of materials that can strongly control near-infrared (NIR) light. Transition metal dichalcogenides (TMDs) have been explored extensively for visible spectrum optoelectronics; the NIR properties of these layered materials have been less-studied. The measurement of optical constants is the foremost step to qualify TMDs for use in NIR photonics. Here, we measure the complex optical constants for select sulfide TMDs (bulk crystals of MoS2, TiS2, and ZrS2) via spectroscopic ellipsometry in the visible-to-NIR range. We find that the presence of native oxide layers (measured by transmission electron microscopy) significantly modifies the observed optical constants and need to be modeled to extract actual optical constants. We support our measurements with density functional theory calculations and further predict large refractive index contrast between different phases. We further propose that TMDs could find use as photonic phase-change materials, by designing alloys that are thermodynamically adjacent to phase boundaries between competing crystal structures, to realize martensitic (i.e., displacive, order–order) switching.
Wake adjustment and vortex-induced vibration of a circular cylinder with a C-shaped plate at a low Reynolds number of 100
Authors: Zhu Hongjun , Wang Kenan
Published: October 2019

The vortex-induced vibration (VIV) of a circular cylinder with a C-shaped plate arranged in its wake at a low Reynolds number of 100 is numerically investigated in this work using the direct numerical simulation. Four typical streamwise spacing ratios of 1.5, 3, 4.5, and 6 are examined in the computations that were carried out for the range of reduced velocities (Ur = 2–12). In terms of shear layer reattachment, wake interference, and vortex shedding, five flow regimes are identified, i.e., the extended-body regime, the front-face reattachment regime, the shear-layer combination regime, the one-row co-shedding regime, and the two-row co-shedding regime. The wake regime is sensitive to the spacing ratio and the reduced velocity. The switching of the flow regime occurs at the transition between the initial VIV branch and the lower VIV branch, accompanying a phase jump of 180°. Furthermore, the shift of the wake regime leads to the prominent fluctuation of the response amplitude. Among the five regimes, the two-row co-shedding regime has the maximum wake width, resulting in the maximum amplitude. In contrast, the shear layers are elongated in the extended-body regime and hence the prolongation of the vortex formation length, contributing to the suppression of VIV. The best suppression is achieved by placing the C-shaped plate behind the cylinder with a spacing of 1.5D, and the reductions in the lift force and the cross-flow amplitude reach 85.5% and 94.5%, respectively.
New approach to development of ultraviolet light-emitting diodes
Authors: Larter Raima
Published: October 2019

Thin films of aluminum nitride grown on silicon carbide wafers show great promise for the production of ultraviolet LEDs.
Simulation of temperature field, flow field and solidification structure for Ag–28Cu–2Ge–0.4Co alloy
Authors: Fang Ji-Heng , Xie Ming , Hu Jie-Qiong , Chen Yong-Tai , Ma Hong-Wei , Li Ai-Kun , Yang You-Cai
Published: October 2019

The temperature field, flow field and solidification structure of Ag–28Cu–2Ge–0.4Co alloy during solidification under water cooling, air cooling and slow cooling conditions were investigated, respectively. The results indicate that the temperature distribution is the most uniform and the solid–liquid phase region is the widest under slow cooling condition. The temperature gradient at the solidification front is the largest under water cooling condition. The solidification rate increases with the distance away from the sidewall under three cooling conditions. Under water-cooled conditions, the liquid flow at the front of the liquidus is much smaller than that in the other two conditions. The ratio of equiaxed crystals and columnar crystals in the solidified structure is different under different cooling conditions.
Existence of multiple positive solutions for p-Laplacian fractional q-difference equations with integral boundary conditions
Authors: Yan Yawen , Hou Chengmin
Published: October 2019

This article studies a boundary value problem of fractional q-difference equations with integral boundary conditions. Some new existence results are obtained by using Avery-Peterson fixed point theorem. An example is also presented to illustrate the effectiveness of the main result.
Study on risk assessment modeling and solution method of fresh agricultural products cold chain logistics
Authors: Zhang Ying , Ge Xueyang
Published: October 2019

Under the market economy environment, consumers’ demands for quick delivery and quality of fresh agricultural products are increasing. At present, the circulation is an important link in the whole industrial chain from production to sales, but there are still problems such as delayed distribution, high logistics cost and serious product loss, which reduce customers’ trust and satisfaction with fresh agricultural products and increase the management risk of fresh agricultural cold chain logistics. In this paper, starting from the systematic management, we maximize customer satisfaction as the important indexes for evaluation of logistics risk, we analyse the distribution of a variety of cost and research with time window of fresh agricultural products cold chain logistics distribution problem, a optimization of fresh agricultural products distribution mathematical model is established, we use genetic algorithm and show the feasibility and effectiveness of the solution through simulation examples.
A novel algorithm for optimal waveform design based on dual mutual information for radar systems
Authors: Xin Fengming , Wang Bin , Xu Zhiyong , Chen Xu
Published: October 2019

In this paper, the authors propose a waveform design algorithm based on dual mutual information criterion in clutter environment for cognitive radar. At the design stage, the authors, determine the optimal waveform according to the criterion: maximizing the mutual information between the received signal and target impulse response while minimizing the mutual information between the received signal and clutter impulse response. Then, considering the transmitted waveform energy constraint, the optimization model for transmitted waveform is established. The maximum marginal allocation algorithm is used to obtain the final optimal waveform. Finally, the algorithm is simulated and its performance is analysed by Lagrange multiplier method. The simulation results demonstrate that the algorithm is validation.
Exponential stability analysis and stabilization for discrete positive switched linear time-delay systems with ADT
Authors: Du Binbin , Hao Shuyan , Lv Chao
Published: October 2019

In this paper, the stability analysis and stabilization problem for discrete positive switched linear time delay system with average dwell time switching are investigated. First, by constructing an appropriate multiple linear co-positive type Lyapunov-Krasovskii functional, sufficient condition for the exponential stability are developed by using ADT approach. Then based on the result obtained a linear feedback law is established for the system to make the state exponentially stable.
Alternative models for the modified form of ridge regularized linear model in discovering Markov boundary
Authors: Yan Shu , Hu Xiaobo , Wang Rujing
Published: October 2019

It has been proved that the modified form of ridge regularized linear model (MRRLM) can discover a subset of Markov boundary of the target variable under some constrained conditions. However, MRRLM cannot be applied to the data sets with collinear variables due to covariance matrix is employed. To develop a suitable alternative model for MRRLM, we study the relationships of discovery performance of Markov boundary among MRRLM, ridge regression linear model (RRLM), and LASSO combining with permutation test through empirical method. In addition, we also proposed a new NVRRLM to discover Markov boundary of the target variable. The experimental results show that: (1) On the binary data sets, MRRLM has a basically similar performance with LASSO and RRLM; (2) On the continuous data sets, MRRLM has a basically similar discovery performance with LASSO but has higher discovery performance than RRLM; (3) The new NVRRLM can replace MRRLM on the data sets with collinear variables. The above experimental results demonstrate NVRRLM can effectively deal with variable collinearity problems.
The electrochemical decoration of multi-walled carbon nanotubes with nickel oxide coating
Authors: Kuz’menko A. P. , Khokhlov N. A. , Hein Kyaw Aung , Than Myo Min , Rodionov V. V.
Published: October 2019

In this paper, nickel coatings have been deposited on the multi-walled carbon nanotubes (MWCNT). In the first stage, MWCNT powder was ultra-wave mixed in the acid bath (H2SO4 and HNO3). The acid treating activates inert carbon surface introducing functional –OH and –COOH groups on the MWCNT surface. The mixture was diluted with distilled water and filtered for several times. The filtered sediment was dried in a plasma cleaner. The powder of such cleaned functionalized MWCNTs (fMWCNTs) was ultrasonicated with deionized water to produce stable colloid. Nickel atoms were injected into the colloid from a positive nickel electrode (with a negative graphite one). The Ni containing tubular nanostructures decorated the fMWCNTs at the specified regulated conditions (temperature, colloid concentration, electric current density). The electrochemically treated colloid was filtered and dried to a powder state (Ni-containing-fMWCNT powder). Hollow NiO nanotubes were produced by the annealing of the powder at 600°C (tubular nanostructured NiO powder). Both powders were examined by the Raman spectroscopy (RS), high-temperature X-ray diffraction (HTXRD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). The estimated high specific surface area of the nanostructured NiO powder is up to 97 m2/g at least and may be varied by time and the electric current of the electrochemical process.
Parameter inversion of cantilever beam based on polynomial model
Authors: Song Yang , Wei Xing , Ye Jing
Published: October 2019

Inverse problem is a kind of problem that “effects” are used to get the “causes”. It has broad application prospects in the field of applied mathematics and physics. The paper makes an inversion analysis based on a cantilever beam via polynomial model. An iterative formula is deduced based on Gauss-Newton method to tackle inherent parameter of cantilever beam. In the process of inversing, direct problem is solved for many times. The polynomial model is constructed and taken as a direct problem solver. The method proposed in this paper can make parameter inversion of cantilever beam with variable Young’s modulus. The result shows that the method has good stability. It can give some guidance for engineers to solve other inversion problem in engineering.