bluuebunny/crossref_metadata_2025_split huggingface dataset:
A review on fabrication of blazed gratings
Authors: Gao Jian , Chen Peng , Wu Lei , Yu Bingjun , Qian Linmao 
Published: April 2021

Abstract
Ultra-precision manufacturing plays a critical role in the successful development of various technological fields and has a significant influence on the processes conducted in human society. Blazed gratings with periodically inclined structures exhibit satisfactory characteristics, concentrating most of the diffracted light to a single, non-zero order. In addition to their high diffraction efficiency, blazed gratings can also significantly improve the sensitivity, resolution, and measurement range of grating measurement systems; they are also core functional components for improving ultra-precision manufacturing. Significant research and industrial attention have been devoted toward the manufacturing of blazed gratings. This review describes the physical principles of blazed gratings, the specific approaches used, and the achievements of typical processing methods, including mechanical ruling, holographic ion beam etching, electron beam lithography, and wet etching. The advantages and disadvantages of these fabrication methods were addressed, and prospective approaches were proposed to improve the manufacturing of blazed gratings.
Vibrational CARS measurements in a near-atmospheric pressure plasma jet in nitrogen: I. Measurement procedure and results
Authors: Kuhfeld J , Lepikhin N D , Luggenhölscher D , Czarnetzki U 
Published: April 2021

Abstract
The non-equilibrium ro-vibrational distribution functions of molecules in a plasma can heavily influence the discharge operation and the plasma-chemistry. A convenient method for measuring the distribution function is coherent anti-Stokes Raman scattering (CARS). CARS spectra are measured in a ns-pulsed plasma between two parallel, 1 mm spaced molybdenum electrodes in nitrogen at 200 mbar with pulse durations of 200 ns/250 ns and a repetition rate of 1 kHz. The CARS spectra are analyzed by a fitting routine to extract information about the vibrational excitation of the nitrogen molecules in the plasma. It is found that during the discharge the vibrational distribution for

v
≲
7

can be described by a vibrational two-temperature distribution function. Additionally, the electric field is measured by the electric field induced second harmonic generation method during the discharge pulse. It is found to be constant in time after the initial ionization wave with values close to 81 Td for the investigated conditions. During the afterglow between two discharge pulses a more general fitting approach is used to obtain the population differences of two neighboring vibrational states. This allows to capture the more complex vibrational dynamics in that time period. The measurement results are discussed in more detail and compared to simple plasma models in a companion paper Kuhfeld et al (2021 J. Phys. D: Appl. Phys.
54 305205).
Doping tuned spin reorientation and spin switching in praseodymium–samarium orthoferrite single crystals
Authors: Luo Xiong , Li Rubin , Ma Xiaoxuan , Chen Yunke , Kang Baojuan , Zhang Jincang , Ren Wei , Feng Zhenjie , Cao Shixun 
Published: April 2021

Abstract
We investigate the detailed analysis of the magnetic properties in a series of Pr1–x
Sm
x
FeO3 single crystals from x = 0 to 1 with an interval of 0.1. Doping controlled spin reorientation transition temperature T
SR Γ4 (G

x
, A

y
, F

z
) to Γ2 (F

x
, C

y
, G

z
) covers a wide temperature range including room temperature. A ‘butterfly’-shape type-I spin switching with 180° magnetization reversal occurs below and above the magnetization compensation points in x = 0.4 to 0.8 compounds. Interestingly, in Pr0.6Sm0.4FeO3 single crystal, we find an inadequate spin reorientation transition accompanied by uncompleted type-I spin switching in the temperature region from 138 to 174 K. Furthermore, a type-II spin switching appears at 23 K, as evidenced from the magnetization curve in field-cooled-cooling (FCC) mode initially bifurcate from zero-field-cooled (ZFC) magnetization curve at 40 K and finally drops back to coincide the ZFC magnetization value at 23 K. Our current research reveals a strong and complex competition between Pr3+–Fe3+ and Sm3+–Fe3+ exchange interactions and more importantly renders a window to design spintronic device materials for future potential applications.
Rigorous 3D modeling of confocal microscopy on 2D surface topographies
Authors: Pahl Tobias , Hagemeier Sebastian , Bischoff Jörg , Manske Eberhard , Lehmann Peter 
Published: April 2021

Abstract
Although optical 3D topography measurement instruments are widespread, measured profiles suffer from systematic deviations occurring due to the wave characteristics of light. These deviations can be analyzed by numerical simulations. We present a 3D modeling of the image formation of confocal microscopes. For this, the light-surface interaction is simulated using two different rigorous methods, the finite element method and the rigorous coupled-wave analysis. The image formation in the confocal microscope is simulated using a Fourier optics approach. The model provides high accuracy and advantages with respect to the computational effort as a full 3D model is applied to 2D structures and the lateral scanning process of the confocal microscope is considered without repeating the time consuming rigorous simulation of the scattering process. The accuracy of the model is proved considering different deterministic surface structures, which usually cause strong systematic deviations in measurement results. Further, the influences of apodization and a finite pinhole size are demonstrated.
Electronic properties of atomically coherent square PbSe nanocrystal superlattice resolved by Scanning Tunneling Spectroscopy
Authors: Capiod Pierre , van der Sluijs Maaike , de Boer Jeroen , Delerue Christophe , Swart Ingmar , Vanmaekelbergh Daniel 
Published: April 2021

Abstract
Rock-salt lead selenide nanocrystals can be used as building blocks for large scale square superlattices via two-dimensional assembly of nanocrystals at a liquid-air interface followed by oriented attachment. Here we report Scanning Tunneling Spectroscopy measurements of the local density of states of an atomically coherent superlattice with square geometry made from PbSe nanocrystals. Controlled annealing of the sample permits the imaging of a clean structure and to reproducibly probe the band gap and the valence hole and conduction electron states. The measured band gap and peak positions are compared to the results of optical spectroscopy and atomistic tight-binding calculations of the square superlattice band structure. In spite of the crystalline connections between nanocrystals that induce significant electronic couplings, the electronic structure of the superlattices remains very strongly influenced by the effects of disorder and variability.
Controllable high-performance memristors based on 2D Fe2GeTe3 oxide for biological synapse imitation
Authors: Zeng Xiangyu , Huang Shuyi , Ye Qikai , Rajagopalan Pandey , Li Wei , Kuang Haoze , Ye Ge , Chen Chufan , Li Menglu , Liu Yulu , Shi Lin , Guo Yuzheng , Lu Xin , Shi Wenhua , Luo Jikui , Wang Xiaozhi 
Published: April 2021

Abstract
Memristors are an important component of the next-generation artificial neural network, high computing systems, etc. In the past, two-dimensional materials based memristors have achieved a high performance and low power consumption, though one at the cost of the other. Furthermore, their performance can not be modulated frequently once their structures are fixed, which remains the bottleneck in the development. Herein, a series of forming free memristors are fabricated with the same Cu/Fe3GeTe2 oxide/Fe3GeTe2/Al structure, yet the On/Off ratio and set voltage is modulated continuously by varying the oxidation time during fabrication. With an optimal oxidation time, a large On/Off ratio (1.58 × 103) and low set voltage (0.74 V) is achieved in a single device. The formation and rapture of Al conductive filaments are found to be responsible for the memristors, and the filaments density and the cross-section area increase with the increase of current compliance, which achieves a higher On/Off ratio. The memristor can imitate basic biological synaptic functions using voltage pulses, demonstrating the potential for low-power consuming neuromorphic computing applications.
Nonlinear localized waves for a (2+1)-dimensional Heisenberg ferromagnetic spin chain equation
Authors: Du Xia-Xia , Tian Bo , Zhang Chen-Rong , Chen Su-Su 
Published: April 2021

Abstract
We focus on the spin dynamics of the nonlinear localized waves for a (2+1)-dimensional Heisenberg ferromagnetic spin chain equation. Based on the technique for the nonlinearization of spectral problem, we derive the values of the spectral parameter and periodic eigenfunction of the Lax pair associated with dn which is the Jacobian elliptic function of the third kind. According to the Darboux transformation, we take the seed solutions expressed by the Jacobian elliptic function and construct the semirational solutions. Such solutions are used for describing the eye-shaped lumps and line rogue waves on the dn-periodic backgrounds. Besides, the lump and mixed lump-soliton solutions are deduced through the semirational solutions.
Entropy and stochastic properties in catalysis at nanoscale
Authors: Castellanos-Jaramillo Juan Miguel , Castellanos-Moreno Arnulfo 
Published: April 2021

Abstract
This work approaches the Michaelis-Menten model for enzymatic reactions at a nanoscale, where we focus on the quasi-stationary state of the process. The entropy and the kinetics of the stochastic fluctuations are studied to obtain new understanding about the catalytic reaction. The treatment of this problem begins with a state space describing an initial amount of substrate and enzyme-substrate complex molecules. Using the van Kampen expansion, this state space is split into a deterministic one for the mean concentrations involved, and a stochastic one for the fluctuations of these concentrations. The probability density in the fluctuation space displays a behavior that can be described as a rotation, which can be better understood using the formalism of stochastic velocities. The key idea is to consider an ensemble of physical systems that can be handled as if they were a purely conceptual gas in the fluctuation space. The entropy of the system increases when the reaction starts and slightly diminishes once it is over, suggesting: 1. The existence of a rearrangement process during the reaction. 2. According to the second law of thermodynamics, the presence of an external energy source that causes the vibrations of the structure of the enzyme to vibrate, helping the catalytic process. For the sake of completeness and for a uniform notation throughout this work and the ones referenced, the initial sections are dedicated to a short examination of the master equation and the van Kampen method for the separation of the problem into a deterministic and stochastic parts. A Fokker-Planck equation (FPE) is obtained in the latter part, which is then used as grounds to discuss the formalism of stochastic velocities and the entropy of the system. The results are discussed based on the references cited in this work.
Ultra-slow-roll inflation with quantum diffusion
Authors: Pattison Chris , Vennin Vincent , Wands David , Assadullahi Hooshyar 
Published: April 2021

Abstract
We consider the effect of quantum diffusion on the dynamics of the inflaton during a period of ultra-slow-roll inflation. We extend the stochastic-δ𝒩 formalism to the ultra-slow-roll regime and show how this system can be solved analytically in both the classical-drift and quantum-diffusion dominated limits.
By deriving the characteristic function, we are able to construct the full probability distribution function for the primordial density field. In the diffusion-dominated limit, we recover an exponential tail for the probability distribution, as found previously in slow-roll inflation.
To complement these analytical techniques, we present numerical results found both by very large numbers of simulations of the Langevin equations, and through a new, more efficient approach based on iterative Volterra integrals.
We illustrate these techniques with two examples of potentials that exhibit an ultra-slow-roll phase leading to the possible production of primordial black holes.
deep21: a deep learning method for 21 cm foreground removal
Authors: Makinen T. Lucas , Lancaster Lachlan , Villaescusa-Navarro Francisco , Melchior Peter , Ho Shirley , Perreault-Levasseur Laurence , Spergel David N. 
Published: April 2021

Abstract
We seek to remove foreground contaminants from 21 cm intensity mapping observations. We demonstrate that a deep convolutional neural network (CNN) with a UNet architecture and three-dimensional convolutions, trained on simulated observations, can effectively separate frequency and spatial patterns of the cosmic neutral hydrogen (HI) signal from foregrounds in the presence of noise. Cleaned maps recover cosmological clustering amplitude and phase within 20% at all relevant angular scales and frequencies. This amounts to a reduction in prediction variance of over an order of magnitude across angular scales, and improved accuracy for intermediate radial scales (0.025 < k∥
< 0.075 h Mpc-1) compared to standard Principal Component Analysis (PCA) methods. We estimate epistemic confidence intervals for the network's prediction by training an ensemble of UNets. Our approach demonstrates the feasibility of analyzing 21 cm intensity maps, as opposed to derived summary statistics, for upcoming radio experiments, as long as the simulated foreground model is sufficiently realistic.
We provide the code used for this analysis on GitHub , as well as a browser-based tutorial for the experiment and UNet model via the accompanying Colab notebook .
A novel family of rotating black hole mimickers
Authors: Mazza Jacopo , Franzin Edgardo , Liberati Stefano 
Published: April 2021

Abstract
The recent opening of gravitational wave astronomy has shifted the debate about black hole mimickers from a purely theoretical arena to a phenomenological one. In this respect, missing a definitive quantum gravity theory, the possibility to have simple, meta-geometries describing in a compact way alternative phenomenologically viable scenarios is potentially very appealing. A recently proposed metric by Simpson and Visser is exactly an example of such meta-geometry describing, for different values of a single parameter, different non-rotating black hole mimickers.
Here, we employ the Newman-Janis procedure to construct a rotating generalisation of such geometry. We obtain a stationary, axially symmetric metric that depends on mass, spin and an additional real parameter ℓ. According to the value of such parameter, the metric may represent a rotating traversable wormhole, a rotating regular black hole with one or two horizons, or three more limiting cases. By studying the internal and external rich structure of such solutions, we show that the obtained metric describes a family of interesting and simple regular geometries providing viable Kerr black hole mimickers for future phenomenological studies.
Robustness of purity of quantum channels
Authors: Wang Ying , Luo Yu , Xi Zhengjun 
Published: April 2021

Abstract
Quantifying purity is a basic problem in quantum information theory. When a quantum state passes through a quantum channel, its purity may be changed. In order to explore what role the quantum channel plays in this process, it is necessary to study the purity of quantum channels. In this paper, we formulate the quantum resource theory for channel purity. There are two basic elements in the quantum resource theory for channel purity: free channels and free superchannels. The free channels are completely randomizing channels which neither store nor output purity. The free superchannels are the uniformity preserving superchannels which do not generate resource channels from free ones. We also provide a method for the realization of a uniformity preserving superchannel. We quantify the purity of quantum channels by the robustness and show that the robustness of purity of a quantum channel (RPC) is a purity monotone. We obtain the efficient numerical calculation of RPC through semidefinite programming. Moreover, we find that the RPC has operational significance as the best advantage that one can obtain in the ensemble of quantum state discrimination games. As an application, we also study the RPC for some single-qubit channels.
The influence of Tm3+ to enhance 2.7 μm mid-infrared emission of Er3+ in CaLaGa3O7 crystal
Authors: Liu Yunyun , Pan Fei , Wang Xihu , Gao Ju 
Published: April 2021

Abstract
Er3+/Tm3+:CaLaGa3O7 (abbr. as Er3+/Tm3+:CLGO) crystal was grown successfully by Czochralski technology and detailed spectroscopic analyses were carried out. The effects of Tm3+ on the spectroscopic properties and mutual energy transfer mechanisms were investigated. It is found that the more suitable pumping scheme for laser applications at 2.7 μm laser is 980 nm excitation for Er3+/Tm3+ co-doped CLGO crystal. Under 980 nm excitation, the introductions of Tm3+ are helpful to achieve enhanced mid-infrared (MIR) emissions, as well as reduced near-infrared emissions. Furthermore, the introducing Tm3+ depopulated the lower laser lever through energy transfer and thus reduced the fluorescence lifetime of Er3+ : 4I13/2, without significantly affecting the fluorescence lifetime of the upper laser level Er3+ : 4I11/2, which reduces the self-saturation problem to a great degree. It concludes that this Er3+/Tm3+:CLGO crystal could be a potential MIR gain media for enhanced 2.7 μm laser under 980 nm pumping.
Radiative decay of the Ξ(1620) in a hadronic molecule picture *
Authors: Huang Yin , Yang Feng , Zhu HongQiang 
Published: April 2021

Abstract
Last year, the

state, which is cataloged in the Particle Data Group (PDG) with only one star, was reported again in the

final state by the Belle Collaboration. Its properties, such as the spectroscopy and decay width, cannot be simply explained in the context of conventional constituent quark models. This inspires an active discussion on the structure of this resonance. In this paper, we study the radiative decays of the newly observed

assuming that it is a meson-baryon molecular state of

and

with spin-parity

developed in our previous study. The partial decay widths of the

molecular state into

and

final states through hadronic loops are evaluated using effective Lagrangians. The partial widths for

is evaluated to be approximately

keV, which may be accessible for the LHCb experiment. If

is a

molecule, the radiative transition strength

is considerably small and the decay width is of the order of 0.01 eV. Future experimental measurements of these processes can be useful to test the molecule interpretations of the

.
Tested Performance of JUNO 20” PMTs
Authors: Zhang Haiqiong , Wang Zhimin , Wang Wei , Qin Zhonghua , Olshevskiy Alexander , Anfimov Nikolay , Wonsak Björn , Denis Korablev , Lachenmaier Tobias , Sterr Tobias , Tietzsch Alexander , Wang Jun , Hu Hang , Zhao Rao , Guo Jingyuan 
Published: April 2021

Abstract
The physics goal of the Jiangmen Underground Neutrino Observatory (JUNO) is mainly to determine the neutrino mass hierarchy by precisely measuring the oscillation spectrum with

3
%
/

E

v
i
s

(
M
e
V
)

energy resolution.Totally, about 20, 000 large area 20” tubes with high photon detection efficiency will be used to achieve this requirement, including 5,000 Hamamatsu dynode PMTs and 15,000 NNVT MCP PMTs. The JUNO collaboration has built two systems to check the performances of these tubes, which have been running since July 2017 and about 14000 tubes have been tested, so far. The key parameters compared with vendor data, including operating voltage, photon detection efficiency, dark count rate, rise time, fall time are presented. The selected PMTs meet all the requirements of the JUNO detector.
Tomographic imaging with Compton PET modules: ideal case and first implementation
Authors: Peng P. , Zhang M. , Zeraatkar N. , Qi J. , Cherry S.R. 
Published: April 2021

Abstract
In our previous studies, we demonstrated that the Compton PET module, a layer structure PET detector with side readout, can provide high performance in terms of spatial/energy/timing resolution, as well as high gamma ray detection efficiency. In this study, we investigate how to translate the high performance of the detector module into good quality reconstructed tomographic images. This study is performed using GATE simulation, as well as with physical experiments. Similar detector geometry is used in the simulation and experiment: two identical 4-layer detector modules are placed with face to face distance of 56 mm. In the simulation study, each layer consists of a 1-mm-pitch pixelated crystal array. In the experimental study, each layer is a monolithic crystal, which is virtually binned into 1 mm^2 cells to group single events according to the gamma ray interaction locations. A customized Derenzo phantom was placed between the two detector modules. By rotating the phantom using a motorized rotary stage, data along lines of response (LORs) at different angles were collected for reconstructing the tomographic image. The same reconstruction algorithm was used for both simulation and experimental studies. The results demonstrate that the simulation study could resolve 0.8 mm rods while the experimental study was able to resolve 1.0 mm rods.
Expanding number of Western US urban centers face declining summertime air quality due to enhanced wildland fire activity
Authors: Wilmot T Y , Hallar A G , Lin J C , Mallia D V 
Published: April 2021

Abstract
Combining multiple sources of information on atmospheric composition, wildland fire emissions, and fire area burned, we link decadal air quality trends in Western US urban centers with wildland fire activity during the months of August and September for the years 2000–2019. We find spatially consistent trends in extreme levels (upper quantile) of fine particulate matter (PM2.5), organic carbon, and absorption aerosol optical depth centered on the US Pacific Northwest during the month of August. Emerging trends were also found across the Pacific Northwest, western Montana, and Wyoming in September. Furthermore, we identify potential wildfire emission ‘hotspots’ from trends in wildfire derived PM2.5 emissions and burned area. The spatial correspondence between wildfire emissions hotspots and extreme air quality trends, as well as their concomitant spatial shift from August to September supports the hypothesis that wildfires are driving extreme air quality trends across the Western US. We derive further evidence of the influence of wildland fires on air quality in Western US urban centers from smoke induced PM2.5 enhancements calculated through statistical modeling of the PM2.5-meteorology relationship at 18 Western US cities. Our results highlight the significant risk of increased human exposure to wildfire smoke in August at these Western US population centers, while also pointing to the potential danger of emerging trends in Western US population growth, wildfire emissions, and extreme air quality in September.