bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulsed vs dc I-V measurements on AlxV1-xO2 (x = 0–0.013) single crystals: Unmasking a non-thermal electric field effect on these crystals
Authors: Patlagan L. , Taitler I. , Reisner G. M. , Fisher B.
Published: November 2021

The thermally induced insulator–insulator transition in Al-doped and the insulator–metal transition in doped as well as in pure VO2 single crystals are replicated in their dc I-V characteristics due to self-heating. In the investigation reported herein, self-heating (a lattice effect) was totally or almost totally avoided by using current pulses of millisecond durations, thus leaving the stage for electron heating. At low currents, the pulsed I-V are close to, or perfectly Ohmic, corresponding to the room temperature value of the resistance. Above a threshold, the voltage jumped backward and the current upward, marking a finite drop in resistance by 12%–24% for the different crystals; from there on, the resistance decreased linearly with the increasing voltage. Most R(V) traces were reproducible with small hysteresis upon increasing and decreasing currents. This behavior suggests an insulator-mixed-metal-insulator transition with metallic domains increasing with the increasing voltage (current). No reproducible behavior of the pulsed I-V characteristic of Al-doped crystals suggests onset of a non-thermal insulator–insulator transition. The interesting question now is what is the true nature of the material under the high pulsed voltage.
Transition pathways connecting crystals and quasicrystals
Authors: Yin Jianyuan , Jiang Kai , Shi An-Chang , Zhang Pingwen , Zhang Lei
Published: November 2021

Significance

Despite the fact that tremendous efforts have been made on the study of quasicrystals since their discovery in 1984, nucleation of quasicrystals—the emergence of a quasicrystal from a crystalline phase—still presents an unsolved problem. The difficulties lie in that quasicrystals and crystals are incommensurate structures in general, so there are no obvious epitaxial relations between them. We solved this problem by applying an efficient numerical method to Landau theory of phase transitions and obtained the accurate critical nuclei and transition pathways connecting crystalline and quasicrystalline phases. The proposed computational methodology not only reveals the mechanism of nucleation of quasicrystals, but also paves the way to investigate a wide range of physical problems undergoing the first-order phase transitions.
Forecast-based attribution of a winter heatwave within the limit of predictability
Authors: Leach Nicholas J. , Weisheimer Antje , Allen Myles R. , Palmer Tim
Published: November 2021

Significance

The question of how humans have influenced individual extreme weather events is both scientifically and socially important. However, deficiencies in climate models’ representations of key mechanisms within the process chains that drive weather reduce our confidence in estimates of the human influence on extreme events. We propose that using forecast models that successfully predicted the event in question could increase the robustness of such estimates. Using a successful forecast means we can be confident that the model is able to faithfully represent the characteristics of the specific extreme event. We use this forecast-based methodology to estimate the direct radiative impact of increased CO2concentrations (one component, but not the entirety, of human influence) on the European heatwave of February 2019.
Metagenomic discovery of CRISPR-associated transposons
Authors: Rybarski James R. , Hu Kuang , Hill Alexis M. , Wilke Claus O. , Finkelstein Ilya J.
Published: November 2021

Significance

CRISPR-Cas systems confer bacteria and archaea with adaptive immunity against mobile genetic elements. These systems also participate in other cellular processes. For example, CRISPR-associated Tn7 transposons (CASTs) have co-opted nuclease-inactive CRISPR effector proteins to guide their transposition. We bioinformatically survey metagenomic databases to uncover CASTs, including systems with new architectures and ones that use distinct CRISPR subtypes. We also describe a putative non-Tn7 CAST that co-opts Cas12. Our findings propose mechanisms for vertical and horizontal CAST targeting and shed light on how CASTs have coevolved with CRISPR-Cas systems.
Kinematic self-replication in reconfigurable organisms
Authors: Kriegman Sam , Blackiston Douglas , Levin Michael , Bongard Josh
Published: November 2021

Significance

Almost all organisms replicate by growing and then shedding offspring. Some molecules also replicate, but by moving rather than growing: They find and combine building blocks into self-copies. Here we show that clusters of cells, if freed from a developing organism, can similarly find and combine loose cells into clusters that look and move like they do, and that this ability does not have to be specifically evolved or introduced by genetic manipulation. Finally, we show that artificial intelligence can design clusters that replicate better, and perform useful work as they do so. This suggests that future technologies may, with little outside guidance, become more useful as they spread, and that life harbors surprising behaviors just below the surface, waiting to be uncovered.
Redox conditions correlated with vibronic coupling modulate quantum beats in photosynthetic pigment–protein complexes
Authors: Higgins Jacob S. , Allodi Marco A. , Lloyd Lawson T. , Otto John P. , Sohail Sara H. , Saer Rafael G. , Wood Ryan E. , Massey Sara C. , Ting Po-Chieh , Blankenship Robert E. , Engel Gregory S.
Published: November 2021

Significance

Photosynthetic organisms evolved their light-harvesting antenna complexes to optimize energy transfer. It was recently shown that the redox environment can tune the mixing of electronic and vibrational states to steer energy through different pathways of a pigment–protein complex. Quantum beating signals in the spectra of pigment–protein complexes have been used to probe the excited-state dynamics within the complexes, but the microscopic dynamics that generate these signals and their role in promoting energy transfer are not fully understood. Here, we show that the redox environment that tunes energy transfer similarly tunes the quantum beating signals in the same complex. We find that the beats report on excited-state vibrations that maintain coherence through the vibronically enhanced energy transfer process.
Quinoa, potatoes, and llamas fueled emergent social complexity in the Lake Titicaca Basin of the Andes
Authors: Miller Melanie J. , Kendall Iain , Capriles José M. , Bruno Maria C. , Evershed Richard P. , Hastorf Christine A.
Published: November 2021

Significance

Food production systems are critical components in the emergence of complex socioecological systems. In the Andes, societal complexity has often been related to the increasing production and consumption of maize by elites, but the importance of highland cultivated crops, such as potatoes, one of the most cultivated crops in the world, and quinoa, presently recognized as a “superfood,” remains largely underappreciated. Using stable isotopes including compound-specific amino acids, we reconstruct the diets of people living in southern Lake Titicaca, where the Tiwanaku state emerged. Over time, locally produced potatoes, quinoa, and llamas, by means of increasingly intensive practices, facilitated long-term food security, which sustained population growth, contributed to increasing sociopolitical complexity, and facilitated resiliency through episodes of significant climatic variation.
Persuading US White evangelicals to vaccinate for COVID-19: Testing message effectiveness in fall 2020 and spring 2021
Authors: Bokemper Scott E. , Gerber Alan S. , Omer Saad B. , Huber Gregory A.
Published: November 2021

The development of COVID-19 vaccines was an important breakthrough for ending the pandemic. However, people refusing to get vaccinated diminish the level of community protection afforded to others. In the United States, White evangelicals have proven to be a particularly difficult group to convince to get vaccinated. Here we investigate whether this group can be persuaded to get vaccinated. To do this, we leverage data from two survey experiments, one fielded prior to approval of COVID-19 vaccines (study 1) and one fielded after approval (study 2). In both experiments, respondents were randomly assigned to treatment messages to promote COVID-19 vaccination. In study 1, we find that a message that emphasizes community interest and reciprocity with an invocation of embarrassment for choosing not to vaccinate is the most effective at increasing uptake intentions, while values-consistent messaging appears to be ineffective. In contrast, in study 2 we observe that this message is no longer effective and that most messages produce little change in vaccine intent. This inconsistency may be explained by the characteristics of White evangelicals who remain unvaccinated vis à vis those who got vaccinated. These results demonstrate the importance of retesting messages over time, the apparent limitations of values-targeted messaging, and document the need to consider heterogeneity even within well-defined populations. This work also cautions against drawing broad conclusions from studies carried out at a single point in time during the COVID-19 pandemic.
Individual and combined impact of physical fitness on health‐related quality of life during adolescence: DADOS Study
Authors: Solera‐Sanchez Alba , Adelantado‐Renau Mireia , Moliner‐Urdiales Diego , Beltran‐Valls Maria Reyes
Published: November 2021

The purpose of the present study was to investigate the individual and combined impact of physical fitness components at baseline on health‐related quality of life (HRQoL) at 24‐month follow‐up in adolescents. This longitudinal research included 199 adolescents (13.9 ± 0.3 years at baseline) from the DADOS study. Cardiorespiratory fitness was assessed using the 20‐m shuttle run test. Muscular strength was assessed using the standing broad jump test. Motor competence was assessed using the 4 × 10‐m shuttle run test. A physical fitness z‐score was calculated as the mean of the z‐scores values of each fitness test. A fitness index ranging from 0 to 3 was created according to the number of physical fitness components in which participants achieved high levels according to normative values. HRQoL was evaluated by the KIDSCREEN‐10 questionnaire. Linear regression analyses showed that cardiorespiratory fitness, muscular strength, and the physical fitness z‐score at baseline were individually associated with HRQoL at follow‐up (β ranging from 0.123 to 0.183; all p < 0.05). Moreover, logistic regression analysis revealed that adolescents with a fitness index ≥1 at baseline were more likely to achieve high HRQoL at 24‐month follow‐up, compared with their peers with an index of 0 (OR ranging from 3.554 to 9.087; all p < 0.05). Our results revealed an individual and cumulative positive impact of physical fitness at baseline on HRQoL at 24‐month follow‐up. These findings underline the key role of promoting the enhancement of overall physical fitness components in order to improve adolescents’ health and well‐being.

Highlights

Adolescents with high levels of cardiorespiratory fitness, muscular strength and motor competence will benefit from a greater physical and mental well‐being over the time.

The more physical fitness components with optimal levels, the greater likelihood of reaching better HRQoL over the time.

Public health authorities should focus on the promotion of multiple physical fitness components to increase adolescent's likelihood of achieving greater HRQoL over the time.
First-order perturbations of Gödel-type metrics in non-dynamical Chern–Simons modified gravity
Authors: Altschul B , Nascimento J R , Petrov A Yu , Porfírio P J
Published: November 2021

Gödel-type metrics that are homogeneous in both space and time remain, like the Schwarzschild metric, consistent within Chern–Simons modified gravity; this is true in both the non-dynamical and dynamical frameworks, each of which involves an additional pseudoscalar field coupled to the Pontryagin density. In this paper, we consider stationary first-order perturbations to these metrics in the non-dynamical framework. Under certain assumptions we find analytical solutions to the perturbed field equations. The solutions of the first-order field equations break the translational and cylindrical symmetries of the unperturbed metrics. The effective potential controlling planar geodesic orbits is also affected by the perturbation parameter, which changes the equilibrium radii for the orbits of both massive particles and massless photons.
Barnich–Troessaert bracket as a Dirac bracket on the covariant phase space
Authors: Wieland Wolfgang
Published: November 2021

The Barnich–Troessaert bracket is a proposal for a modified Poisson bracket on the covariant phase space for general relativity. The new bracket allows us to compute charges, which are otherwise not integrable. Yet there is a catch. There is a clear prescription for how to evaluate the new bracket for any such charge, but little is known how to extend the bracket to the entire phase space. This is a problem, because not every gravitational observable is also a charge. In this paper, we propose such an extension. The basic idea is to remove the radiative data from the covariant phase space. This requires second-class constraints. Given a few basic assumptions, we show that the resulting Dirac bracket on the constraint surface is nothing but the BT bracket. A heuristic argument is given to show that the resulting constraint surface can only contain gravitational edge modes.
Einstein gravity as a gauge theory for the conformal group
Authors: Herfray Yannick , Scarinci Carlos
Published: November 2021

General relativity in dimension n = p + q can be formulated as a gauge theory for the conformal group

S
O

p
+
1
,
q
+
1

, along with an additional field reducing the structure group down to the Poincaré group

I
S
O

p
,
q

. In this paper, we propose a new variational principle for Einstein geometry which realizes this fact. Importantly, as opposed to previous treatments in the literature, our action functional gives first order field equations and does not require supplementary constraints on gauge fields, such as torsion-freeness. Our approach is based on the ‘first order formulation’ of conformal tractor geometry. Accordingly, it provides a straightforward variational derivation of the tractor version of the Einstein equation. To achieve this, we review the standard theory of tractor geometry with a gauge theory perspective, defining the tractor bundle a priori in terms of an abstract principal bundle and providing an identification with the standard conformal tractor bundle via a dynamical soldering form. This can also be seen as a generalization of the so called Cartan–Palatini formulation of general relativity in which the ‘internal’ orthogonal group

S
O

p
,
q

is extended to an appropriate parabolic subgroup

P
⊂
S
O

p
+
1
,
q
+
1

of the conformal group.
Photothermal liquid release from arrayed Au nanorod/hydrogel composites for chemical stimulation
Authors: Seo Sang-Woo , Song Youngsik , Rostami Azmand Hojjat
Published: November 2021

Controlled photothermal actuation of liquid release is presented using periodically arrayed hydrogel columns in a macroporous silicon membrane. Thermo-responsive hydrogel is mixed with Gold (Au) nanorods, and surface plasmon-induced local heating by near-infrared (NIR) light is utilized as an actuation method. We adopted theoretical modeling, which treats the hydrogel as a poro-viscoelastic medium to understand the mechanical and liquid transport properties of the hydrogel. To demonstrate the feasibility of the liquid release control using NIR light, we first characterized the temperature response of Au nanorod embedded hydrogel in the silicon membrane using its optical transmission behavior to confirm the successful device fabrication. Next, the liquid release characteristics from the structure were studied using fluorescent imaging of fluorescein dye solution while pulsed NIR light was illuminated on the structure. We successfully demonstrate that the liquid release can be controlled using remote NIR illumination from the presented structure. Considering the periodically arrayed configuration with high spatial resolution, this will have a potential prospect for optically-addressable chemical release systems, which benefit retina prosthesis interfaces.
Mode coupling and locking of a Π-shaped cantilever resonator using laser-induced asymmetric modulation
Authors: Luo Wenyao , Gao Naikun , Li Yanyan , Zhao Zhixin , Liu Duo
Published: November 2021

Mechanical resonators, such as microcantilevers, demonstrate significant potential for use in information technology. Cantilevered beams of various geometries clamped at one end form the most ubiquitous structures in microelectromechanical systems that support multimode vibration for the detection, conversion, and processing of small signals. In this study, we demonstrate that the potential of these devices can be further extended by utilizing a strategy based on mode coupling and locking induced by asymmetric photothermal modulation. A cantilever was designed to have a Π-shape with a specific geometry such that the resonant frequencies of the two orthogonal modes are close to one another. Additionally, we show that mode coupling between the two modes, which are originally orthogonal to one another, can be achieved through laser-induced photothermal modulation. In particular, the two modes can be parametrically tuned to become degenerate through mode coupling with a significant increase in the quality factor from 112 to 839. This approach is universal and can be extended to improve the detection limits of microresonators in high-dissipation environments with enhanced signal-to-noise ratios.
Tunable gigahertz dynamics of low-temperature skyrmion lattice in a chiral magnet
Authors: Lee Oscar , Sahliger Jan , Aqeel Aisha , Khan Safe , Seki Shinichiro , Kurebayashi Hidekazu , Back Christian H
Published: November 2021

Recently, it has been shown that the chiral magnetic insulator Cu2OSeO3 hosts skyrmions in two separated pockets in temperature and magnetic field phase space. It has also been shown that the predominant stabilization mechanism for the low-temperature skyrmion (LTS) phase is via the crystalline anisotropy, opposed to temperature fluctuations that stabilize the well-established high-temperature skyrmion (HTS) phase. Here, we report on a detailed study of LTS generation by field cycling, probed by GHz spin dynamics in Cu2OSeO3. LTSs are populated via a field cycling protocol with the static magnetic field applied parallel to the ⟨100⟩ crystalline direction of plate and cuboid-shaped bulk crystals. By analyzing temperature-dependent broadband spectroscopy data, clear evidence of LTS excitations with clockwise (CW), counterclockwise (CCW), and breathing mode (BR) character at temperatures below T = 40 K are shown. We find that the mode intensities can be tuned with the number of field-cycles below the saturation field. By tracking the resonance frequencies, we are able to map out the field-cycle-generated LTS phase diagram, from which we conclude that the LTS phase is distinctly separated from the high-temperature counterpart. We also study the mode hybridization between the dark CW and the BR modes as a function of temperature. By using two Cu2OSeO3 crystals with different shapes and therefore different demagnetization factors, together with numerical calculations, we unambiguously show that the magnetocrystalline anisotropy plays a central role for the mode hybridization.
Enhancing the hybridization of plasmons in graphene with 2D superconductor collective modes
Authors: Costa A T , Peres N M R
Published: November 2021

We explore ways in which the close proximity between graphene sheets and monolayers of 2D superconductors can lead to hybridization between their collective excitations. We consider heterostructures formed by combinations of graphene sheets and 2D superconductor monolayers. The broad range of energies in which the graphene plasmon can exist, together with its tunability, makes such heterostructures promising platforms for probing the many-body physics of superconductors. We show that the hybridization between the graphene plasmon and the Bardasis–Schrieffer mode of a 2D superconductor results in clear signatures on the near-field reflection coefficient of the heterostructure, which in principle can be observed in scanning near-field microscopy experiments.
Prediction of solar cell materials via unsupervised literature learning
Authors: Zhang Lei , He Mu
Published: November 2021

Despite the significant advancement of the data-driven studies for physical science, the textual data that are numerous in the literature are not fully embraced by the physics and materials community. In this manuscript, we successfully employ the natural language processing (NLP) technique to unsupervisedly predict the existence of solar cell types including the dye-sensitized solar cells and the perovskite solar cells based on literatures published prior to their first discovery without human annotation. Enlightened by this, we further identify possible solar cell material candidates via NLP starting with a comprehensive training database of 3.2 million paper abstracts published before 2021. The NLP model effectively predicts the existing solar cell materials, while an uncommon solar cell material namely PtSe2 is suggested as an appropriate candidate for the future solar cells. Its optoelectronic properties are comprehensive investigated via first-principles calculations to reveal the decent stability and optoelectronic performance of the NLP-predicted candidate. This study demonstrates the viability of the textual data for the data-driven materials prediction and highlights the NLP method as a powerful tool to reliably predict the solar cell materials.
Development and evaluation of the effectiveness of educational material for radiological protection that uses augmented reality and virtual reality to visualise the behaviour of scattered radiation
Authors: Nishi Kazuki , Fujibuchi Toshioh , Yoshinaga Takashi
Published: November 2021

Understanding the behaviour of scattered radiation is important for learning appropriate radiation protection methods, but many existing visualisation systems for radiation require special devices, making it difficult to use them in education. The purpose of this study was to develop teaching material for radiation protection that can help visualise the scattered radiation with augmented reality (AR) and virtual reality (VR) on a web browser, develop a method for using it in education and examine its effectiveness. The distribution of radiation during radiography was calculated using Monte Carlo simulation, and teaching material was created. The material was used in a class for department of radiological technology students and its influence on motivation was evaluated using a questionnaire based on the evaluation model for teaching materials. In addition, text mining was used to evaluate impressions objectively. Educational material was developed that can be used in AR and VR for studying the behaviour of scattered radiation. The results of the questionnaire showed that the average value of each item was more than four on a five-point scale, indicating that the teaching material attracted the interest of users. Through text mining, it could be concluded that there was improved understanding of, and confidence in, radiation protection.
Role of thermal history on atomic structure and ductility of ion-irradiated metallic glasses
Authors: Chen Tzu-Chia , Raya Indah , Shafik Shafik S , Jabbar Abdullah Hasan , Tumanov Dmitry , Surendar Aravindhan , Sevbitov Andrei , Hoi Huynh Tan , Mustafa Yasser Fakri , Vladimirovich Kabanov Oleg , Kadhim Mustafa M , Sajjadifar Sami , Repnikov Nikolay I
Published: November 2021

Maximizing the structural rejuvenation and ductility is one of the most heated debates in the field of metallic glasses (MGs). In this work, molecular dynamics simulation was implemented to model the ion irradiation effects on the Cu60Zr40 MG with different thermal histories and varied structural heterogeneities. The initial results indicated that the performance of an annealing–quench treatment on the MG induces the atomic configurations with different heterogeneities and potential energy values. The subsequent ion irradiation process also demonstrated that an optimized atomic structure was occurred for achieving maximum rejuvenation and ductility in the CuZr glassy alloy. It was unveiled that the intermediate initial heterogeneity provides an efficient pathway for maximizing the atomic rearrangements under the ion irradiation. It was also suggested that the medium population of Cu-centered clusters in the initial state facilitated the atomic rearrangements during the ion irradiation process. The structural characteristics and atomic reconfigurations for attaining the optimum ductility is discussed in details.
Surface energies and relaxation of NiCoCr and NiFeX (X
= Cu, Co or Cr) equiatomic multiprincipal element alloys from first principles calculations
Authors: Li Wei , Peng Xianghe , Ngan Alfonso H W , El-Awady Jaafar A
Published: November 2021

First principles calculations of the energies and relaxation of unreconstructed low-index surfaces, i.e. (001), (011) and (111) surfaces, in NiCoCr and NiFeX (X = Cu, Co or Cr) equiatomic multi-principal element alloys (MPEAs) are presented. The calculations were conducted for 12-layer slabs represented by special quasi-random supercells using the projector augmented wave method within the generalized gradient approximation. While experimental predictions are unavailable for comparison, the calculated surface energies agree fairly well with those from thermodynamic modeling and a bond-cutting model. In addition, the calculations unveil an important surface structure, namely, that the topmost surface layer is in contraction except for the (001) surface of NiFeCr alloy, the next layer below is in extension, and the bulk spacing is gradually recovered from the subsequent layers down. Additionally, the surface contraction is the most pronounced on the (011) plane, being about 4%–10% relative to the bulk spacings. The results presented here can provide an understanding of surface-controlled phenomena such as corrosion, catalytic activities and fracture properties in these equiatomic MPEAs.
Enhanced magnetic performance in exchange-coupled CoFe2O4–LaFeO3 nanocomposites
Authors: Sharma Priyanka , Jain Anjali , Chatterjee Ratnamala
Published: November 2021

Nanocomposite oxide system of (x)CoFe2O4–(100-x)LaFeO3 with different weight percent of core-shell structured CoFe2O4 (x = 0, 20, 40, 50, 80, 100) and LaFeO3 were fabricated, via a two-step sol-gel wet-chemical synthesis technique. The phase formation of the composites was confirmed by x-ray diffraction and the structural parameters of both the phases were attained from the Rietveld refinement results of XRD patterns. The elemental composition and microstructure of the resulting nanocomposites were examined by using energy-dispersive x-ray spectroscopy and high-resolution transmission electron microscopy technique, respectively. The detailed magnetometry studies at 300 K and 5 K reveal that the inter-and intra-phase magnetic interactions affect the saturation magnetization (M
S), remanence magnetization (M
R) and coercivity (H
C) values of this bi-magnetic system. The remarkable feature of ‘pinched magnetic hysteresis loop’ was evidenced in the [(50) CoFe2O4 - (50)LaFeO3] composite, leading to a lesser magnetic loss factor and better magnetic performance of this sample. The report depicts an improved interfacial exchange coupling at 5 K, for the nanocomposites of core-shell morphology and offers an understanding or explanation of improved magnetic performance for the (50)CoFe2O4 - (50)LaFeO3 nanocomposite and opens up an important way to design new multiferroic applications in low magnetic fields.
Controllable synthesis of Mo2C with different morphology and application to electrocatalytic hydrogen evolution reaction
Authors: Chang He-Qiang , Zhang Guo-Hua , Chou Kuo-Chih
Published: November 2021

In order to evaluate the effect of precursors and synthesis strategies on catalytic ability of Mo2C in the hydrogen evolution reaction (HER), four kinds of Mo2C were synthesized using two kinds of MoO3 by two strategies. Compared with the one-step direct carbonization strategy, Mo2C with a large special surface area and a better performance could be synthesized by the two-step strategy composed of a nitridation reaction and a carbonization reaction. Additionally, the as-prepared porous Mo2C nanobelts (NBs) exhibit good electrocatalytic performance with a small overpotential of 165 mV (0.5 M H2SO4) and 124 mV (1 M KOH) at 10 mA cm−2, as well as a Tafel slope of 58 mV dec−1 (0.5 M H2SO4) and 59 mV dec−1 (1 M KOH). The excellent catalytic activity is ascribed to the nano crystallites and porous structure. What’s more, the belt structure also facilitates the charge transport in the materials during the electrocatalytic HER process. Therefore, the two-step strategy provides a new insight into the structural design with superior performance for electrocatalytic HER.
Fabrication of periodic microscale stripes of silver by laser interference induced forward transfer and their SERS properties
Authors: Shen Huijuan , Wang Yaode , Cao Liang , Xie Ying , Wang Lu , Chu Xueying , Shi Kaixi , Wang Shenzhi , Yu Miaomiao , Liu Ri , Zhang Jingran , Li Changli , Weng Zhankun , Wang Zuobin
Published: November 2021

The micro-stripe structure was prepared by laser interference induced forward transfer technique, composed of Ag nano-particles (NPs). The effects of the film thickness with the carbon nano-particles mixed polyimide (CNPs@PI), Ag film thickness, and laser fluence were studied on the transferred micro-stripe structure. The periodic Ag micro-stripe with good resolution was obtained in a wide range of CNPs@PI film thickness from ∼0.5 to ∼1.0 μm for the Ag thin film ∼20 nm. The distribution of the Ag NPs composing the micro-stripe was compact. Nevertheless, the average size of the transferred Ag NPs was increased from ∼41 to ∼197 nm with the change of the Ag donor film from ∼10 to ∼40 nm. With the increase of the laser fluence from 102 to 306 mJ·cm−2 per-beam, the transferred Ag NPs became aggregative, improving the resolution of the corresponding micro-stripe. Finally, the transferred Ag micro-stripe exhibited the significant surface enhanced Raman scattering (SERS) property for rhodamine B (RhB). While the concentration of the RhB reached 10–10 mol·L−1, the Raman characteristic peaks of the RhB were still observed clearly at 622, 1359 and 1649 cm−1. These results indicate that the transferred Ag micro-stripe has potential application as a SERS chip in drug and food detection.
Experimental determination of modulation power of lung tissue for particle therapy
Authors: Burg Jan Michael , Flatten Veronika , Witt Matthias , Derksen Larissa , Weber Uli , Engenhart-Cabillic Rita , Vorwerk Hilke , Zink Klemens , Baumann Kilian-Simon
Published: November 2021

In particle therapy of lung tumors, modulating effects on the particle beam may occur due to the microscopic structure of the lung tissue. These effects are caused by the heterogeneous nature of the lung tissue and cannot be completely taken into account during treatment planning, because these micro structures are too small to be fully resolved in the planning CT. In several publications, a new material parameter called modulation power (P

mod
) was introduced to characterize the effect. For various artificial lung surrogates, this parameter was measured and published by other groups and ranges up to approximately 1000 μm. Studies investigating the influence of the modulation power on the dose distribution during irradiation are using this parameter in the rang of 100–800 μm. More precise measurements for P

mod
on real lung tissue have not yet been published. In this work, the modulation power of real lung tissue was measured using porcine lungs in order to produce more reliable data of P

mod
for real lung tissue. For this purpose, ex-vivo porcine lungs were frozen in a ventilated state and measurements in a carbon ion-beam were performed. Due to the way the lungs were prepared and transferred to a solid state, the lung structures that modulate the beam could also be examined in detail using micro CT imaging. An optimization of the established methods of measuring the modulation power, which takes better account of the typical structures within lung tissue, was developed as well.
Effects of 4d transition metal Pd doping on the magnetic and superconducting properties of 112-type iron pnictide EuFeAs2
Authors: Zhan Xinhui , Yi Xiaolei , Xing Xiangzhuo , Li Meng , Yu Linchao , Huang Song , Feng Jiajia , Meng Yan , Zhou Nan , Liu Xiaobing , Shi Zhixiang
Published: November 2021

The recently discovered 112-type EuFeAs2 compound that shows complex Eu-spin magnetism provides a new platform to study the interplay between superconductivity (SC) and magnetism in iron pnictide superconductors. In this paper, by substituting Fe with the 4d transition metal (TM) Pd, we have synthesized a series of EuFe1−x
Pd
x
As2 (0 ⩽ x ⩽ 0.08) samples and studied the doping effect on SC and magnetism by means of electrical transport and magnetization measurements. The systematic evolution of the lattice parameters indicates that the Pd atoms have been successfully substituted into the Fe sites. With Pd doping, the Fe-related spin density wave transition at

T

m

Fe

in the parent phase is rapidly suppressed, and SC simultaneously emerges, exhibiting a domelike shape with a maximum onset transition temperature

T

c

onset

of around 18.5 K at x = 0.04. On the other hand, the Eu-related antiferromagnetic order at

T

m

Eu

is suppressed very slowly and persists up to x = 0.08, covering the whole SC dome region. Also, the reentrant spin-glass and spin-reorientation transitions below

T

m

Eu

remain unchanged with Pd doping. All these results indicate that the Eu spins have little effect on SC in EuFe1−x
Pd
x
As2. Finally, based on the resistivity and magnetization data, the T − x phase diagram of EuFe1−x
Pd
x
As2 is constructed and compared with those of 3d TMs Co/Ni and La doped ones.
MHD simulations of cold bubble formation from 2/1 tearing mode during massive gas injection in a tokamak
Authors: Zeng Shiyong , Zhu Ping , Izzo V.A. , Li Haolong , Jiang Zhonghe
Published: November 2021

Massive gas injection (MGI) experiments have been carried out in many tokamaks to study disruption dynamics and mitigation schemes. Two events often observed in those experiments are the excitation of the m = 2, n = 1 magnetohydrodynamic mode, and the formation of cold bubble structure in the temperature distribution before the thermal quench (TQ). Here m is the poloidal mode number, n the toroidal mode number. The physics mechanisms underlying those phenomena, however, have not been entirely clear. In this work, our recent NIMROD simulations of the MGI process in a tokamak have reproduced the main features of both events, which has allowed us to examine and establish the causal relation between them. In these simulations, the 3/1 and 2/1 islands are found to form successively after the arrival of impurity ion cold front at the corresponding q = 3 and q = 2 rational surfaces. At the interface between impurity and plasma, a local thin current sheet forms due to an enhanced local pressure gradient and moves inward following the gas cold front, this may contribute to the formation of a dominant 2/1 mode. Following the growth of the 2/1 tearing mode, the impurity penetration into the core region inside the q = 2 surface gives rise to the formation of the cold bubble temperature structure and initiates the final TQ. A subdominant 1/1 mode developed earlier near the q = 1 surface alone does not cause such a cold bubble formation, however, the exact manner of the preceding impurity penetration depends on the nature of the 1/1 mode: kink-tearing or quasi-interchange.
Understanding core tungsten (W) transport and control in an improved high-performance fully non-inductive discharge on EAST
Authors: Shi Shengyu , Chen Jiale , Bourdelle Clarisse , Jian Xiang , Odstrčil Tomáš , Garofalo Andrea M. , Cheng Yunxin , Chao Yan , Zhang Ling , Duan Yanmin , Wu Muquan , Ding Fang , Li Yingying , Huang Juan , Qian Jinping , Gao Xiang , Wan Yuanxi
Published: November 2021

The behavior of heavy/high-Z impurity tungsten (W) in an improved high-performance fully non-inductive discharge on EAST with ITER-like divertor (ILD) is analyzed. It is found that W could be well controlled. The causes of no W accumulation are clarified by analyzing the background plasma parameters and modeling the W transport. It turns out that the electron temperature (T
e) and its gradient are usually high while the toroidal rotation and density peaking of the bulk plasma are small. In this condition, the modeled W turbulent diffusion coefficient is big enough to offset the total turbulent and neoclassical pinch, so that W density profile for zero particle flux will not be very peaked. Combining NEO and TGLF for the W transport coefficient and the impurity transport code STRAHL, not only the core W density profile is predicted but also the radiated information mainly produced by W in the experiment can be closely reconstructed. At last, the physics of controlling W accumulation by electron cyclotron resonance heating (ECRH) is illustrated considering the effects of changed T
e by ECRH on ionization balance and transport of W. It shows that the change of ionization and recombination balance by changed T
e is not enough to explain the experimental observation of W behavior, which should be attributed to the changed W transport. By comparing the W transport coefficients in two kinds of plasmas with different T
e profiles, it is shown that high T
e and its gradient play a key role to generate large turbulent diffusion through increasing the growth rate of linear instability so that W accumulation is prevented.
Background estimate in heavy-ion two-body reactions measured by the MAGNEX spectrometer
Authors: Calabrese S. , Cappuzzello F. , Carbone D. , Cavallaro M. , Agodi C. , Torresi D. , Acosta L. , Bonanno D. , Bongiovanni D. , Borello-Lewin T. , Boztosun I. , Brischetto G. , Calvo D. , Ciraldo I. , Deshmukh N. , de Faria P.N. , Finocchiaro P. , Foti A. , Gallo G. , Hacisalihoglu A. , Iazzi F. , Introzzi R. , Lanzalone G. , Linares R. , Longhitano F. , Presti D. Lo , Medina N. , Muoio A. , Oliveira J.R.B. , Pakou A. , Pandola L. , Pinna F. , Reito S. , Russo G. , Santagati G. , Sgouros O. , Solakci S.O. , Soukeras V. , Souliotis G. , Spatafora A. , Tudisco S. , Zagatto V.A.B.
Published: November 2021

The MAGNEX magnetic spectrometer is nowadays used in the experimental measurements of rare quasi-elastic reactions between heavy ions at intermediate energy within the NUMEN project. The small cross sections involved in such processes under the large yields due to competitive reaction channels have motivated an accurate control of the background sources. In such view, the not ideal particle identification could introduce spurious contributions which have been identified and evaluated in the present analysis.
Optical and mathematical method for studying electrode discharge spots with a liquid electrode
Authors: Tazmeev B Kh , Tsybulevsky V V
Published: November 2021

High-speed visualization of the discharge with a liquid cathode, color image processing were performed. The area of cathode spots concentration was identified. Statistical characteristics of the distribution of cathode spots were obtained in order to determine the range in which the intensity code of the green color channel changes, the polygon function of the empirical distribution of the intensity code for the green color channel. The graphical dependence on the frequency of the cathode spot indication hit into the specified interval of the color intensity code was created.
Numerical study of a model of terahertz collective modes in DNA
Authors: Zakhvataev V E , Volodko O S , Kompaniets L A , Zlobin D V
Published: November 2021

Terahertz density fluctuations in DNA have been recognized to be associated with biological function of DNA and widely studied both experimentally and theoretically. In the present work, we investigate numerically a new model for the terahertz dynamics of density fluctuations in DNA, proposed earlier. This model considers the length scales corresponding to wave numbers up to the position of the maximum of the static structure factor and allows to reflect structural effects caused by the dependence of the static structure factor on wave number. We study the parametric dependencies of the model to elucidate the effect of dlocalization of the dynamics of density fluctuations caused by structural effects.
Investigation rectifier circuits based on the mathematical models in the two-dimensional space
Authors: Hien Nguyen Thi , Zaslavskiy A A
Published: November 2021

The mathematical model for the rectifier circuit using semiconductor diodes is setup in this paper. The properties of the rectifier circuit presented by the ordinary differential equation containing a control parameter K. When K is large enough, the studied equation gives a trajectory approximating to a trajectory of the rectifier circuit above. The theorem about the approximation of these solutions with arbitrary small error (this error can be controlled by increasing K). The usefulness of this model is illustrated via concrete example. This study can to get more profound results in further and investigate an optimal process for an assembly line of rectifiers in electrical engineering.
Physics of evolution and unity of physics
Authors: Somsikov V M , Abylay A M , Kuvatova D B
Published: November 2021

The article considers the question of the possibility of constructing classical mechanics and empirical branches of physics, such as thermodynamics, statistical physics and kinetics on a general theoretical basis. The principles of constructing mechanics, thermodynamics, statistical physics, and kinetics are briefly given. It is shown how the construction of the above sections of physics on a unified basis became possible, relying on the mechanics of a structured body. The essence of this mechanics is that, unlike Newton’s mechanics, built for a body model in the form of a material point, this mechanics is built based on a body model in the form of a structured body. Moreover, the structured body is specified in the form of an equilibrium system of potentially interacting material points. It is shown how the equation of motion of a structured body is derived. The peculiarity of this equation is that it takes into account the transformation of the energy of motion of a structured body into internal energy when it moves in an inhomogeneous field of forces. This makes it possible to describe dissipative processes within the framework of the mechanics of a structured body without invoking statistical laws. Examples are given of how the empirical principles of the phenomenological branches of physics directly follow from the fundamental laws of physics.
Numerical analysis of the stability of nonequilibrium 3D evolutionary transfer processes in the network
Authors: Provotorov V V , Part A A , Shleenko A V , Sergeev S M
Published: November 2021

Analytical methods for solving various problems of an applied nature (for example, non-stationary transfer problems over network hydro, gas and heat carriers), whose mathematical models use the formalisms of evolutionary differential systems, are possible with rare exceptions. That is why the construction of numerical and simulation models for the use of quantitative analysis methods becomes a universal research tool, if at the same time the implementation of these models on a computer is carried out – in other words, a complex of software engineering of the process under study is formed. The study uses the method of semidiscretization by a time variable of the mathematical model of the evolutionary non-equilibrium process of continuous medium transfer, which remains one of the most effective methods for analyzing applied problems. In this case, the elliptic operator of the mathematical model has a special basis (a system of eigenfunctions), which is why the analysis is reduced to the study of a boundary value problem for elliptic-type equations with a spatial variable changing on a network-like domain. The paper presents the conditions for unambiguous weak solvability of a differential-difference system, which is a difference analogue in the time variable of the original system, and the way of constructing an algorithm for finding an approximate solution is indicated. The study contains an analysis of the stability and convergence of difference schemes of evolutionary network-like nonequilibrium processes of continuous media transfer over network carriers and includes an analysis of the correctness of the mathematical model of this process. The results of the work are applicable in the framework of oil and gas engineering to the study of issues of stabilization and parametric optimization of the processes of transportation of liquid media through spatial networks.
Reduction of scattering cross section of path antennas
Authors: Ryzhikov M B , Novikova Yu A
Published: November 2021

This report considers the possibility of reducing the scattering cross section of patch antennas when using emitters of various shapes and when using structures with non-zero surface resistance. The report presents the results of the influence of the choice of the shape of a emitter on the SCS in the region of resonant scattering frequencies. The scattering indicatrices of various emitters for the resonant scattering frequency are analyzed. Comparative analysis results of the decrease estimation for the SCS of the square path when using various forms of regions with impedance surface are presented.
Analysis of ellipsometric parameters in the reflection of circularly polarized light from a thin anisotropic plate
Authors: Yatsyshen V V
Published: November 2021

The article presents the results of the analysis of the angular spectra of the ellipsometric parameters of the reflected wave when a circularly polarized light wave is incident on an anisotropic plate. The given dependences show a very high sensitivity of the ellipsometric parameters of the reflected light on the angle of incidence and the angle between the optical axis and the normal to the plate boundary. The energy reflection spectra themselves show much less variability when these parameters change. It should be especially emphasized the nature of the change in the ellipsometric angle Δ, which is responsible for the type of elliptical polarization - when Δ> 0, the polarization is left-handed, and when Δ <0, it is right-handed. It is shown that a thin anisotropic plate at certain angles can serve as a polarization converter of the incident radiation. The ellipsometry parameter ρ characterizes the degree of compression of the ellipse - when ρ = 1, the ellipse is transformed into a circle, and the light is circularly polarized in this case. Thus, a thin anisotropic plate can not only convert left-handed polarization to right-handed, but it can also control the very shape of the polarization ellipse. Such a plate can be used in conjunction with a layered medium, for example, a one-dimensional photonic crystal, to control the polarization of the incident circularly polarized light.
Analysis of dynamic circuits of contactless switching devices
Authors: Abduraimov E Kh , Khalmanov D Kh , Nurmatov B A , Peysenov M B , Toirova N J
Published: November 2021

The main content of the study is the analysis of theoretical and virtual-experimental studies and methods of analysis of transients in semiconductor nonlinear dynamic circuits of contactless switching devices, presents transient graphs constructed using a virtual computer model. In addition, presents solutions of differential equations of the state of such circuits by the numerical Euler method.