bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of COVID-19 on agricultural production and food security: A scientometric analysis
Authors: Okolie Collins C. , Ogundeji Abiodun A. 
Published: February 2022

AbstractCoronavirus disease has created an unexpected negative situation globally, impacting the agricultural sector, economy, human health, and food security. This study examined research on COVID-19 in relation to agricultural production and food security. Research articles published in Web of Science and Scopus were sourced, considering critical situations and circumstance posed by COVID-19 pandemic with regards to the shortage of agricultural production activities and threat to food security systems. In total, 174 published papers in BibTeX format were downloaded for further study. To assess the relevant documents, authors used “effects of COVID-19 on agricultural production and food security (ECAP-FS) as a search keyword for research published between 2016 and April 2021 utilising bibliometric innovative methods. The findings indicated an annual growth rate of about 56.64%, indicating that research on ECAP-FS increased over time within the study period. Nevertheless, the research output on ECAP-FS varied with 2020 accounting for 38.5%, followed by 2021 with 37.9% as at April 2021. The proposed four stage processes for merging two databases for bibliometric analyses clearly showed that one can run collaboration network analyses, authors coupling among other analyses by following our procedure and finally using net2VOSviewer, which is embedded in Rstudio software package. The study concluded that interruptions in agricultural food supply as a result of the pandemic impacted supply and demand shocks with negative impacts on all the four pillars of food security.
Study of second optical harmonic generation in terahertz pulse-induced antiferromagnetic NiO
Authors: Chefonov O.V. , Ovchinnikov A.V. , Agranat M.B. 
Published: February 2022

Abstract
Intense terahertz pulses and a process of second harmonic generation are promising methods for exciting and studying an ultrafast dynamic response in magnetically ordered systems, ferroelectrics, and multiferroics on the picosecond time scale. In the present work, we report experimental results on generation of second optical harmonic in centrosymmetric antiferromagnetic NiO induced by intense terahertz pulses with an electric field strength of up to 20 MV cm−1.
Phase combining of radiation from a two-channel explosively pumped photodissociation iodine laser with an SBS mirror
Authors: Garanin S.G. , Dolgopolov Yu.V. , Kachalin G.N. , Kopalkin A.V. , Kulikov S.M. , Pevnyi S.N. , Starikov F.A. , Sukharev S.A. 
Published: February 2022

Abstract
A two-channel double-pass iodine explosively pumped photodissociation laser (EPPL) with an explosively pumped master oscillator (MO) and an SBS mirror is studied. The radiation source, determined by an aperture 6 mm in diameter, through which the radiation from MO enters the turbulent surface air path, is located at a distance of 2.5 km from the amplifier unit input. An SBS mirror with a kinoform raster of microlenses is used to compensate for the amplifier and path optical inhomogeneities and to match the phases in the EPPL channels. The energy and spatial characteristics of the EPPL output radiation are studied experimentally and numerically. Good agreement is obtained between the experimental and calculated distribution of the energy density of the output EPPL radiation in the plane of the MO aperture, which is a pattern of interference between the two channels. The maximum energy density in the aperture plane is by more than 4 times greater than in the case of a single-channel EPPL.
Light bullets in transparent dielectrics
Authors: Kandidov V.P. , Zaloznaya E.D. , Dormidonov A.E. , Kompanets V.O. , Chekalin S.V. 
Published: February 2022

AbstractThis paper presents a retrospective analysis of the development of notions in nonlinear optics: from beam self-focusing and pulse filamentation to light bullets – wave packets extremely compressed in space and time during laser light propagation in the bulk of a transparent medium. We describe the state of the art in studies of mid-IR light bullets in condensed media and air.
Post-compression of femtosecond laser pulses using self-phase modulation: from kilowatts to petawatts in 40 years
Authors: Khazanov E.A. 
Published: February 2022

AbstractThe pulse duration at the output of femtosecond lasers is usually close to the Fourier limit, and can be shortened by increasing the spectral width. To this end, use is made of self-phase modulation when a pulse propagates in a medium with cubic nonlinearity. Then, the pulse with a chirp (frequency dependence of the spectrum phase) is compressed due to a linear dispersion element, which introduces a chirp of the same modulus, but opposite in sign. This pulse post-compression, known since the 1960s, has been widely used and is being developed up to the present for pulses with energies from fractions of a nJ to tens of J. The review is devoted to the theoretical foundations of this method, problems of energy scaling, and a discussion of the results of more than 150 experimental studies.
Efficient SRS of chirped Ti : sapphire laser pulses in BaWO4 crystals
Authors: Kinyaevskiy I.O. , Kovalev V.I. , Koribut A.V. , Grudtsyn Ya.V. , Seleznev L.V. , Dunaeva E.E. , Ionin A.A. 
Published: February 2022

Abstract
We report an experimental study of SRS of chirped 40-ps Ti : sapphire laser pulses with a transform-limited duration of 0.35 ps and centre wavelength of 925 nm in BaWO4 crystals. The highest generation efficiency for the ∼925 cm−1 shifted Stokes signal of SRS by the ν
1 vibrational mode of BaWO4 crystals has been reached using three sequentially located crystals with a total length of 3.3 cm. The position of the crystals after a focusing mirror has been optimised, which has ensured a pump-to-Stokes conversion efficiency of ∼50 % in terms of spectral brightness and ∼20 % in terms of pulse energy.
Broadband two-dimensional spectrochronography with ultrashort pulses in the mid-infrared
Authors: Stepanov E.A. , Zhdanov A.N. , Savitskii I.V. , Glek P.B. , Lanin A.A. , Fedotov A.B. , Zheltikov A.M. 
Published: February 2022

AbstractA novel, 2.6-to-10-μm wavelength-tunable laser source of sub-70-fs pulses is combined with mid-IR heterodyne detection to provide a versatile laser platform for broadband two-dimensional Fourier-transform infrared spectrochronography. The mid-infrared laser output serves as both a short-pulse driver and a broadband probe for time-resolved studies of ultrafast molecular coherence, population dynamics, and multimodal energy transfer in a vast class of complex molecular systems.
A quantum corrected R–N–AdS black hole and it’s thermodynamics of phase transition
Authors: Wu Shanping , Liu Chengzhou 
Published: February 2022

Abstract
To investigate the quantum gravity effects on the black hole thermodynamics, we studied the phase transition in a quantum corrected R–N–AdS black holes. First, based on the work of Kazakov and Solodukhin, the spherically symmetric quantum fluctuation is applied to R–N–AdS black hole, and the metric is given. Next, we investigate the basic thermodynamic quantity and Smarr formula, and then propose that the quantum correction parameter a should also be treated as a variable to ensure the establishment of the new Smarr formula. Finally, the P–V diagram and phase transition for the quantum corrected R–N–AdS black hole are studied. Compared with the existing research on R–N–AdS black hole, some effects by quantum fluctuation are analyzed and presented. First, the quantum correction will weaken the charge effect of the black hole. Second, the P–V curve of the quantum corrected black hole is no longer analogous to that of Van Der Waals (VDW) gas exactly. Third, the black hole has two more phase states than R–N–AdS black hole. One is a remnant phase state, the other is an unstable phase state. And both are derived from the quantum corrections of the black hole.
High precision six-degree-of-freedom interferometer for test mass readout
Authors: Yan Hao , Yeh Hsien-Chi , Mao Qiuli 
Published: February 2022

Abstract
High precision six-degree-of-freedom sensing plays an important role in future gravitational space missions. In gravitational or geodesy missions, measurements of all six degrees of freedom of freely floating test mass are required for reducing the cross-coupling noise, which is frequently an important limiting factor in the performance. Interferometry and capacitive sensing have been successfully combined in LISA pathfinder to achieve six degrees of freedom measurements. In this paper, we report a six-degree-of-freedom interferometer system based on multiplex differential wavefront sensing and longitudinal pathlength sensing. Compared to conventional capacitive sensing or optical levers, it has a higher measurement accuracy. The results of our table-top experiment show motion in all six degrees of freedom of a cubic test mass are simultaneously measured with a translational and tilt sensitivity of 100 pm/Hz1/2 and 10 nrad Hz−1/2 above 1 Hz, respectively. The translational dynamic range is greater than ±10 mm with nonlinear residuals less than 6 μm, and the tilt dynamic range is approximately ±500 μrad with nonlinear residuals less than 60 μrad. The coupling errors between multiple degrees of freedom are dominated by tilt-to-translation and tilt-to-tilt coupling, which are roughly 2–4 μm and 15–25 μrad, respectively, within a range of [−500 μrad, +500 μrad].
Zeta function regularization technique in the electrostatics context for discrete charge distributions
Authors: Escalante F 
Published: February 2022

Abstract
Spectral functions, such as the zeta functions, are widely used in quantum field theory to calculate physical quantities. In this work, we compute the electrostatic potential and field due to an infinite discrete distribution of point charges, using the zeta function regularization technique. This method allows us to remove the infinities that appear in the resulting expression. We found that the asymptotic behavior dependence of the potential and field is similar to the cases of continuous charge distribution. Finally, this exercise can be useful for graduate students to explore spectral and special functions.
Carbon K-edge x-ray emission spectroscopy of gas phase ethylenic molecules
Authors: Ingle R A , Banerjee A , Bacellar C , Barillot T R , Longetti L , Coreno M , de Simone M , Zuccaro F , Poletto L , Miotti P , Röder A , Stolow A , Schuurman M S , Odelius M , Chergui M 
Published: February 2022

Abstract
We report on the C K-edge x-ray absorption spectra and the resonant (RXES) and non-resonant (NXES) x-ray emission spectra of ethylene, allene and butadiene in the gas phase. The RXES and NXES show clear differences for the different molecules. Overall both types of spectra are more structured for ethylene and allene, than for butadiene. Using density functional theory–restricted open shell configuration interaction single calculations, we simulate the spectra with remarkable agreement with the experiment. We identify the spectral features as being due to transitions involving localised 1s orbitals. For allene, there are distinct spectral bands that reflect transitions predominantly from either the central or terminal carbon atoms. These results are discussed in the context of ultrafast x-ray studies aimed at detecting the passage through conical intersections in polyatomic molecules.
Review of in-space plasma diagnostics for studying the Earth’s ionosphere
Authors: Velásquez-García Luis Fernando , Izquierdo-Reyes Javier , Kim Hyeonseok 
Published: February 2022

Abstract
This review details the state of the art in in-space plasma diagnostics for characterizing the Earth’s ionosphere. The review provides a historical perspective, focusing on the last 20 years and on eight of the most commonly used plasma sensors—most of them for in situ probing, many of them with completed/in-progress space missions: (a) Langmuir probes, (b) retarding potential analysers, (c) ion drift meters, (d) Faraday cups, (e) integrated miniaturized electrostatic analysers, (f) multipole resonance probes, (g) Fourier transform infrared spectrometers, and (h) ultraviolet absorption spectrometers. For each sensor, the review covers (a) a succinct description of its principle of operation, (b) highlights of the reported hardware flown/planned to fly in a satellite or that could be put in a CubeSat given that is miniaturized, and (c) a brief description of the space missions that have utilized such sensor and their findings. Finally, the review suggests tentative directions for future research.
Energy conversion mechanisms of a seesaw-type energy harvester
Authors: Zhong Xiang , Wang Buyi , Li Rong , Wu Yimin , Ma Mengchao , Deng Huaxia 
Published: February 2022

Abstract
Vibration energy harvesters with bistable characteristics, which can convert mechanical energy to electric energy, are typically cantilever beams with magnetic repulsion. In order to enhance their low-frequency performance, a seesaw-type approach has been proposed, which can make the structure overcome the potential barrier more easily. In this paper, we establish electromechanical coupling equations of the whole system, and prove that the internal beam delivers mechanical energy to the primary beam based on time-domain analysis. Meanwhile, frequency-domain analysis and solutions are conducted to investigate the dynamical and electrical behaviors of the system based on the adjustment of different parameters. We find that both the mechanical and electrical responses are enhanced gradually with the decrease of the relative damping coefficient within the bounds of the discussion. And the maximum response amplitude can be increased by a factor of 11.3 just by adjusting the position of the internal beam. Furthermore, the length of the internal beam can affect the responses of the system visibly and regularly, and the maximum response amplitude remains unchanged when changing the length of the internal beam from 80 to 100 mm. All of this suggests that the mechanisms of a seesaw-type energy harvester will provide guidance for designing a more appropriate structure, depending on different applications.
Modulation of the dielectric property of Ga2O3/TiO2 nanolaminates and their improvement on the electroluminescence from devices based on Er-doped Al2O3 nanofilms
Authors: Yuan Kang , Ma Rui , Yang Li , Yang Yang , Sun Jiaming 
Published: February 2022

Abstract
Metal-oxide-semiconductor light-emitting devices (MOSLEDs) based on the erbium doped Al2O3 nanofilms still suffer from insufficient and unstable electrical injection, and the dielectric protection layers play an important role in their performance. Here, Ga2O3/TiO2 (GTO) nanolaminate films are fabricated by atomic layer deposition, the dielectric constant and leakage current of which are gradually regulated by alternating the component ratios. The tolerance to electric field and electron injection for the Al2O3:Er MOSLEDs is significantly improved, leading to the enhanced electroluminescence performance. The optimal GTO nanolaminate with thickness ratio of 4:6 could withstand the maximum breakdown electric field reaching 4.17 MV cm−1 while maintaining a high electric field of 8.4 ± 0.1 MV cm−1 within the luminescent Al2O3:Er layer (under injection of 0.3 A cm−2), resulting in the optical power density up to 11.37 mW cm−2. Much higher excitation efficiencies are also achieved with external quantum efficiency of 19.35%, and the operation time of the prototype Al2O3:Er MOSLEDs is significantly enhanced by more than two orders of magnitude from 48 s (I= 0.2 μA) to 7308 s (I = 1 μA). The design principle of the dielectric nanolaminates has been deduced, considering the dielectric and conductive contribution of different oxides, which supplies a promising route to further explore the application of optoelectronic devices based on oxides.
Raman scattering studies of the ambient atmospheric thermal stability of Be in periodic Be/Mo and Be/W multilayer mirrors
Authors: Kumar Niranjan , Antisheva Galina D , Nezhdanov Aleksey V , Drozdov Mikhail N , Pleshkov Roman S , Yunin Pavel A , Polkovnikov Vladimir N , Chkhalo Nikolay I 
Published: February 2022

Abstract
The ambient atmospheric thermal stability of beryllium (Be) layers in Be/Mo and Be/W multilayer mirrors was investigated by Raman scattering. The physical characteristic of the transverse optical (TO) mode was considered for structural analysis of the Be layers in the multilayers. With an increase in thermal annealing temperature, two important modifications of this mode were noticed: the TO mode of Be was found to shift to a lower frequency and the peak width became wider. These two facts are related to the deterioration of the crystalline quality of the Be layers upon thermal annealing. The TO mode of the crystalline Be phase completely vanished and high-intensity peaks at the shoulder were detected for the Be/Mo multilayer thermally annealed at 723 K. This evidence is associated with the transformation of polycrystalline into an oxidized amorphous Be phase. In this case, the diffusion of oxygen to the inner period and the destruction of the modulation of the periodic structure of the multilayer was investigated by a secondary ion mass spectrometer. However, the TO mode of Be embedded within W in Be/W multilayers was stable in similar annealing conditions, which revealed the thermal stability.
Dynamics of two-dimensional liquid bridges
Authors: Coelho Rodrigo C V , Cordeiro Luís A R G , Gazola Rodrigo B , Teixeira Paulo I C 
Published: February 2022

Abstract
We have simulated the motion of a single vertical, two-dimensional liquid bridge spanning the gap between two flat, horizontal solid substrates of given wettabilities, using a multicomponent pseudopotential lattice Boltzmann method. For this simple geometry, the Young–Laplace equation can be solved (quasi-)analytically to yield the equilibrium bridge shape under gravity, which provides a check on the validity of the numerical method. In steady-state conditions, we calculate the drag force exerted by the moving bridge on the confining substrates as a function of its velocity, for different contact angles and Bond numbers. We also study how the bridge deforms as it moves, as parametrized by the changes in the advancing and receding contact angles at the substrates relative to their equilibrium values. Finally, starting from a bridge within the range of contact angles and Bond numbers in which it can exist at equilibrium, we investigate how fast it must move in order to break up.
Superconducting dome associated with the suppression and re-emergence of charge density wave states upon sulfur substitution in CuIr2Te4 chalcogenides
Authors: Boubeche Mebrouka , Wang Ningning , Sun Jianping , Yang Pengtao , Zeng Lingyong , Luo Shaojuan , He Yiyi , Yu Jia , Wang Meng , Cheng Jinguang , Luo Huixia 
Published: February 2022

Abstract
We report the path from the charge density wave (CDW)-bearing superconductor CuIr2Te4 to the metal insulator transition (MIT)-bearing compound CuIr2S4 by chemical alloying with the gradual substitution of S for Te. The evolution of structural and physical properties of the CuIr2Te4−x
S
x
(0 ⩽ x ⩽ 4) polycrystalline system is systemically examined. The x-ray diffraction (XRD) results imply CuIr2Te4−x
S
x
(0 ⩽ x ⩽ 0.5) crystallizes in a NiAs defected trigonal structure, whereas it adapts to the cubic spinel structure for 3.6 ⩽ x ⩽ 4 and it is a mixed phase in the doping range of 0.5 < x < 3.6. Unexpectedly, the resistivity and magnetization measurements reveal that small-concentration S substitution for Te can suppress the CDW transition, but it reappears around x = 0.2, and the CDW transition temperature enhances clearly as x augments for 0.2 ⩽ x ⩽ 0.5. Besides, the superconducting critical temperature (T
c) first increases with S doping content and then decreases after reaching a maximum T
c = 2.82 K for CuIr2Te3.85S0.15. MIT order has been observed in the spinel region (3.6 ⩽ x ⩽ 4) associated with T
MI increasing with x increasing. Finally, the rich electronic phase diagram of temperature versus x for this CuIr2Te4−x
S
x
system is assembled, where the superconducting dome is associated with the suppression and re-emergence of CDW as well as MIT states at the end upon sulfur substitution in the CuIr2Te4−x
S
x
chalcogenides.
Head and abdomen CT exposures in Portugal
Authors: Trindade Hugo , Barreira Marisa , Xavier Cláudia 
Published: February 2022

Abstract
In Portugal, computed tomography (CT) exposures for adult routine head, adult routine abdomen and paediatric abdomen (5 years old) were evaluated between 2019 and 2020 in 92 CT units. The third quartile value for CTDIvol was 63.2 mGy for adult head exams, 15.9 mGy for adult abdomen and 5.2 mGy for paediatric abdomen. However, the CTDIvol for head examination in 7.6% of units exceeded the suspension level proposed in EU report 162 while the number of units exceeding suspension levels for adult and paediatric abdomen were 3.2% and 0.0%, respectively. The used acquisition parameters and the referred CT unit’s specifications were studied to understand how radiation dose relates with tube voltage, tube current, rotation time, detector width, slice width, pitch value and the use of automatic exposure control (AEC). The axial acquisition mode was predominant (67%) in the head exams. However, the helical scanning was commonly used in abdomen exams. Dose reduction from adult to paediatric exams was achieved using a lower tube current (a 60% average reduction). AEC is preferably used in abdomen protocols (84% in adult exams and 96% in paediatric exams). Nonetheless, in adult routine head protocols only 27% used this system. Data was gathered from clinics and hospitals covered by this study which allowed an estimate of an annual frequency of 206 CT examinations per 1000 population in Portugal. The estimated dose index (CTDIvol) and frequency of CT examinations for the Portuguese population agreed with data from other countries.
Micropyramid structured photo capacitive interfaces
Authors: Nikić Marta , Opančar Aleksandar , Hartmann Florian , Migliaccio Ludovico , Jakešová Marie , Głowacki Eric Daniel , Đerek Vedran 
Published: February 2022

Abstract
Optically driven electronic neuromodulation devices are a novel tool in basic research and offer new prospects in medical therapeutic applications. Optimal operation of such devices requires efficient light capture and charge generation, effective electrical communication across the device’s bioelectronic interface, conformal adhesion to the target tissue, and mechanical stability of the device during the lifetime of the implant—all of which can be tuned by spatial structuring of the device. We demonstrate a 3D structured opto-bioelectronic device—an organic electrolytic photocapacitor spatially designed by depositing the active device layers on an inverted micropyramid-shaped substrate. Ultrathin, transparent, and flexible micropyramid-shaped foil was fabricated by chemical vapour deposition of parylene C on silicon moulds containing arrays of inverted micropyramids, followed by a peel-off procedure. The capacitive current delivered by the devices showed a strong dependency on the underlying spatial structure. The device performance was evaluated by numerical modelling. We propose that the developed numerical model can be used as a basis for the design of future functional 3D design of opto-bioelectronic devices and electrodes.