bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-assembly of dumbbell-shaped supramolecules with simulated annealing and Monte Carlo simulation
Authors: Du Bo , Wang Qing , Li Congying , Li Hong
Published: May 2022

The self-assembly structures of dumbbell-shaped supramolecules are investigated using a simple sphere-rod-sphere (SRS) model. Through the simulated annealing Monte Carlo simulation under NVT condition, two variations of this model, i.e. the rigid/semi-rigid model, are compared by their order parameters. We found that, by varying the interactions of this SRS model, various nanostructures such as cross-linked networks, clusters phases, bundle-like nanowires and other order phases are discovered. The formation mechanism of these novel nanostructures is discussed.
Rapid Determination of Antioxidant Irganox 1076 in Polyethylene
Authors: Zheng Qiukai , Hu Dan , Fan Jingjing
Published: May 2022

A method was established to quickly determine the content of antioxidants in polyethylene by Fourier transform infrared spectroscopy. By analyzing the FTIR spectra of the antioxidant Irganox 1076 and PE, the characteristic peak of the antioxidant Irganox 1076 in PE was determined to be the absorption peak at 1738cm-1. According to the standard curve of the antioxidant, the content of the antioxidant had a good linear relationship with the absorption intensity of its characteristic peak, and the linear regression coefficient of the equation was 0.97363. The relative error was less than 7%. The method is accurate and reliable, allowing for rapid quantitative analysis of trace antioxidant content in polyolefin.
Preparation and Thermal Conductivity of FG/PP Composites
Authors: Zhou Haijun , Zhang Xiaolei , Zhou Mengmeng , Wang Zhengzheng , Chen Xiaoqi , Zhang Fen , Xiao Jijun , Li Yantao
Published: May 2022

The surface modified flake graphite (FG) was filled into polypropylene (PP) and mixed by a double-roll open mill. FG/PP composites with high thermal conductivity were prepared by compression molding. Studies had shown that the modification of FG by coupling agent was beneficial to the dispersion in FG/PP composites. The effect was better when the amount of NDZ-201 was 0.7wt%. With the increase of FG particle size, the thermal conductivity of FG/PP composites increased obviously. Compared with 17μm FG, the average, vertical and parallel thermal conductivity of FG/PP composites prepared with 148μm FG increased by 65.9%, 87.7% and 47.0% respectively. The thermal conductivity of FG/PP composites were improved with the increase of FG content. When FG content was 70wt%, the thermal conductivity increased significantly, the average, vertical and parallel thermal conductivity reached 4.16 W·m-1·K-1, 0.938 W·m-1·K-1 and 18.4 W·m-1·K-1.
Statics and Modal Analysis of Main Frame of Composite Board Detaching Sleeve Equipment
Authors: Zhu Wenchang , Hu Guangzhong , Bin Qiuyue , Liao Junjie , Xu Haoming
Published: May 2022

A new type of special machine tool for stripper sleeve was developed according to the stripper sleeve process of composite board. In order to ensure the reliability of the mainframe structure and the performance of the linear guide mechanism, the static structural analysis and modal analysis of the mainframe are carried out. The results show that the maximum stress of the supporting beam under the main frame is about 48.18 MPa, the maximum strain is 0.00023, and the maximum stress of the four-legged column is about 5.35 MPa, which is full of strength and stiffness design requirements. The end-cutting mechanism is installed on the beam through the installation plate. The deformation of the beam has a great influence on the operation accuracy of the linear guide mechanism and the cutting accuracy of the end-cutting mechanism. The maximum displacement in the X and Y directions of the installation plate is 0.014 mm, 0.030 mm and 0.197 mm, respectively, which meets the normal use requirements and cutting accuracy requirements of the linear guide mechanism. The first six natural frequencies of the mainframe are 2.963 – 47.137 Hz. In order to make the mainframe have good dynamic characteristics, avoid resonance and meet the end-cutting requirements of the composite board, the motor speed should be controlled between 300 – 493 r / min.
Influence of Surface Crack Propagation on Ring-Shell Structure
Authors: Lin Haichao
Published: May 2022

In this paper, the surface cracks of deep-sea ring-shell structures are studied. In this paper, the geometric and physical parameters of 1000m underwater titanium alloy ring shell structure were analyzed. Firstly, the mathematical model of its relevant contour curve was obtained by combining with the parameter equation. Based on the mathematical model, the finite element model was established and the force analysis under static equilibrium condition was carried out. Secondly, the stress maximum point was solved by finite element analysis, and the initial crack was added at the stress maximum point. The stress intensity factor method was used to analyze the stress intensity factor and crack propagation. Finally, according to the physical parameter load, stress ratio, morphology coefficient and different Angle analysis, the influence factors that interfere with crack growth and the dynamic trend of crack morphology were evaluated. Aiming at the study of dynamic performance of cracked ring-shell structure, the crack characteristic curves under different complex working conditions were analyzed to deepen the research in related fields and provide some scientific reference for the study of related ring-shell structure.
Effect of different active materials on WAAM depth of penetration and weld morphology
Authors: Huang Yunfeng , Shi Xuezhi
Published: May 2022

The Gas Metal Arc welding process was used to prepare single-track and single-track multilayer samples. The effects of CaF2 and TiO2 on the penetration width and depth of samples are studied. The results show that the addition of these two active agents will reduce the surface morphology quality of single-track, but it will deepen the penetration depth of single-track. Compared with sample of CaF2, sample of TiO2 can maintain a better single track morphology while increasing the penetration. The ratio of effective melting width to maximum melting width is close to that without adding.
Research on influencing factors of fatigue performance of cruciform welded joints on offshore platforms
Authors: Li Da , Su Yunlong , Bai Xueping , Peng Chentao , Xu Lianyong
Published: May 2022

In this study, the fatigue life of load-carrying cruciform welded joints under various plate thicknesses and degrees of penetration was performed. The fatigue assessment results showed a significant “thickness effect.” The fatigue limit of the 25 mm-thick sample was 13.4% lower than that of the 16 mm-thick fatigue sample. Essentially, the fatigue life of the weld toe does not change with the degree of penetration. Plate thickness is the key factor affecting the fatigue life. The thickness effect is determined by both the stress gradient along the plate thickness and the degree of surface stress concentration. The correction result based on the effective notch stress approach is more accurate than the thickness correction formula in the ABS standard, which underestimates the thickness effect of load-carrying cruciform welded joints and may lead to danger. The penetration ratio a/t affects the fatigue failure position of load-carrying cruciform welded joints. The fatigue design of load-carrying cruciform welded joints can be performed by appropriately increasing the degree of penetration while achieving the damage at the weld toe.
Stochastic medical tourism problem with variable residence time considering gravity function
Authors: Hasannia Kolaee Mansoureh , Mirzapour Al-e-Hashem Seyed Mohammad Javad
Published: May 2022

Medical tourism is a recent term in healthcare logistics referring to travel of patients to receive health services and spending leisure time in a destination country. This transferring of patients leads to access high-quality health services which are cheaper than the original country of patients. During this travel, passengers who are the patients from another country, have this opportunity for complimentary entertainment packages (e.g., pleasure tours) in the aftercare period. As far as we know, the term of medical tourism is rarely studied in healthcare logistics and such services are highly important for developing countries. Such facts motivate us to develop a practical optimization model for the Medical Tour Centers (MTCs) for allocation of patients to hospitals in proper time and creation of memorable aftercare time for them. In this regard, the main aim of the proposed model is to maximize the total profit of MTCs through optimal allocation of patients to hospitals while considering an aftercare tour for the passengers. To make the proposed model more realistic, the optimal residence time in attractive places is simulated by a time-dependent gravity function. To address the uncertainty of medical tourism problem, a scenario-based two-stage stochastic optimization approach is extended to encounter different sources of uncertainty existing in surgical success, medical time, restoration restrictions, and the attraction of tourist places. Another novelty of this work is to propose an innovative hybrid meta-heuristic for large-scale instances, which is a combination of Progressive Hedging Algorithm (PHA) and Genetic Algorithm (GA). The model is analyzed by different test problems for small, medium, and large-scale instances where the hybrid meta-heuristic algorithm could solve them with an average gap of 3.4% in comparison with the commercial solver. The results revealed the importance of tourist opinion and public preferences in medical and pleasure tours, respectively, to improve the economic growth in this sector in developing countries.
Minimizing the variance of the coverage ratio as an approach to optimize the exchange rate risk of Brent futures contracts
Authors: Bouchekourte Mustapha , Rhouas Sara , El Hami Norelislam
Published: May 2022

Derivatives markets show that their structure is always characterized by periods of strong price fluctuations. This is true regardless of the underlying asset of the futures contracts considered, whether they are commodities, interest rates, exchange rates, shares, stock market indices, etc. By locking in future prices, the primary objective of these markets is to limit the risks faced by operators. This article proposes a new method of optimizing the coverage ratio by futures contracts to minimize price variance and thus apply this new technique to reduce the risk associated with Brent price volatility for the period from January 2010 to December 2020. The variance minimization model of Ederington's (1979) is the first and most widely used coverage model and the one that dominates the literature on this area which helps to find the optimal coverage ratio, and is also the objective function in our particle assay optimization algorithm in MATLAB and we will better interpret our results with statistical analysis and lastly, we will evaluate the effectiveness of the coverage model.
Insulin-Like Growth Factor-I Might be a Predictor for Severe
Non-Alcoholic Fatty Liver Disease in Morbidly Obese Patients
Authors: Turgut Seda , Acarer Didem , Seyit Hakan , Pamuk Naim , Piskinpasa Hamide , Bozkur Evin , Karabulut Mehmet , Cakir Ilkay
Published: May 2022

The aim of the study was to compare the IGF-1 levels, metabolic and clinical
parameters among the ultrasonographically classified non-alcoholic fatty liver
disease (NAFLD) groups and determine the factors that may predict the NAFLD
severity in patients with morbid obesity. This study was conducted on 316
morbidly obese patients (250 F/66 M). The data of
patients before and 1st-year after bariatric surgery were recorded. According to
the ultrasonographically NAFLD screening, patients with normal hepatic features
were classified as Group 1(n=57), with mild and moderate NAFLD were
classified as Group 2(n=219), and with severe NAFLD were classified as
Group 3(n=40). IGF-1 standard deviation scores (SDSIGF1) were calculated
according to age and gender. Parameters that could predict the presence and
severity of NAFLD were evaluated. IGF-1 levels were significantly associated
with Group 3 than Group 1(p=0.037), and the significance remained
between the same groups when IGF-1 levels were standardized as
SDSIGF1(p=0.036). Decreased levels of SDSIGF1 explained 5% of
severe NAFLD than the normal group (p=0.036). Liver Diameter, FPG, ALT,
AST, and GGT were also found as significant predictors for severe NAFLD. There
were significant differences between pre-and postop values in all groups
(p<0.001). This study showed that IGF-1 might be considered a sgnificant
predictor of severe NAFLD in morbidly obese patients. It is crucial in clinical
practice to determine predictive factors of NAFLD that could support the
diagnosis accompanied by non-invasive imaging methods.
Recyclable Palladium-Catalyzed Carbonylative Coupling of 2-Iodoanilines, Trimethyl Orthoformate, and Amines: A Practical Synthesis of Quinazolin-4(3H)-ones
Authors: Cai Mingzhong , Li Jianying , Zhou Zebiao , Xie Gang
Published: May 2022

An efficient heterogeneous palladium-catalyzed carbonylative annulation of 2-iodoanilines, trimethyl orthoformate, and amines has been developed. The reaction proceeds smoothly in toluene at 110 °C using N,N-diisopropylethylamine (DiPEA) as base and 2 mol% of MCM-41-anchored bidentate phosphine palladium complex [MCM-41-2P-Pd(OAc)2] as catalyst under 10 bar of carbon monoxide and provides a general and practical method for the construction of a wide variety of quinazolin-4(3H)-ones in good to excellent yields from commercially easily available starting materials. This heterogenized palladium catalyst can be easily recovered via a simple centrifugation process and reused more than nine times with almost consistent catalytic efficiency.
Transition to a Night Float System in Ophthalmology Residency: Perceptions of Resident Wellness and Performance
Authors: Aggarwal Sahil , Wisely C. Ellis , Gross Andrew , Challa Pratap
Published: May 2022

Purpose The purpose of this study is to characterize the influence of a new night float rotation on resident wellness and performance in the Duke University Eye Center Ophthalmology Residency Program.

Methods We analyzed three classes of ophthalmology residents: one class (n = 4) utilized the new night float rotation with no daytime clinical duties, while two senior classes (n = 12) utilized the traditional call system wherein they had daytime and nighttime responsibilities. Residents completed a questionnaire regarding their perceptions of the night float rotation. Supervising attendings (n = 15) were also surveyed about their perceptions of the new rotation.

Results Zero of the four residents on the night float rotation reported burnout compared with 6 of 11 residents in the traditional call system. Most residents supported the adoption of the night float rotation, but this trend was less apparent among fellows and attendings.

Most respondents believed the new night float rotation reduced burnout, fatigue, and work hours while increasing time for nonclinical activities. Perceived skills gained while on call were felt to be similar between the two call systems. Fellows and attendings believed residents in the night float system performed similarly or better than residents in the traditional system in indicators such as knowledge and enthusiasm. There was no significant difference in the average number of patient encounters (290.8 ± 30.5 vs. 310.7 ± 25.4, p = 0.163), phone encounters (430.8 ± 20.2 vs. 357.1 ± 90.0, p = 0.068), or average hours worked per week (57.3 ± 4.6 vs. 58.0 ± 5.7 p = 0.797) per resident between night float residents and traditional call residents.

Conclusions This study shows resident support for a night float rotation in ophthalmology residency at Duke, with reductions in burnout and more time for nonclinical activities without affecting perceived clinical performance. We hope this study serves as an impetus for other ophthalmology programs considering a transition to a night float system.
The first 100 years: IR, critical security studies and the quest for peace
Authors: Rolf Jan Niklas
Published: May 2022

This paper argues that peace studies and the Welsh school of critical security studies both define themselves in opposition to the traditional view of security, with the only difference that the former goes through the concept of peace in voicing its critique of security. Pointing to some striking similarities in the epistemology, methodology and ontology of Johan Galtung and Ken Booth, it shows that the two studies have been driving on parallel roads and that they would profit greatly from joining forces. Being the kind of applied and anti-hegemonic science that scholars at Aberystwyth strive for, peace studies could provide the Welsh school with greater practical applicability and access to everyday life. The Welsh school, in turn, could endow peace studies with academic reputation and a solid critical foundation. This would not only put peace back on the agenda of IR, but also contribute towards the decolonization of the discipline.
Polarization and magnetization in collisional and turbulent transport processes
Authors: Sugama H. , Matsuoka S. , Nunami M.
Published: May 2022

Expressions of polarization and magnetization in magnetically confined plasmas are derived, which include full expansions in the gyroradius to treat effects of both equilibrium and microscopic electromagnetic turbulence. Using the obtained expressions, densities and flows of particles are related to those of gyrocenters. To the first order in the normalized gyroradius expansion, the mean part of the particle flow is given by the sum of the gyrocenter flow and the magnetization flow, which corresponds to the so-called magnetization law in drift kinetics, while the turbulent part contains the polarization flow as well. Collisions make an additional contribution to the second-order particle flow. The mean particle flux across the magnetic surface is of the second-order, and it contains classical, neoclassical, and turbulent transport processes. The Lagrangian variational principle is used to derive the gyrokinetic Poisson and Ampère equations, which properly include mean and turbulent parts so as to be useful for full-f global electromagnetic gyrokinetic simulations. It is found that the second-order Lagrangian term given by the inner product of the turbulent vector potential and the drift velocity consisting of the curvature drift and the ∇B drift should be retained in order for the derived Ampère equation to correctly include the diamagnetic current, which is necessary especially for the full-f high-beta plasma simulations. The turbulent parts of these gyrokinetic Poisson and Ampère equations are confirmed to agree with the results derived from the WKB representation in earlier works.
Algebraic structure underlying spherical, parabolic, and prolate spheroidal bases of the nine-dimensional MICZ–Kepler problem
Authors: Le Dai-Nam , Le Van-Hoang
Published: May 2022

The nonrelativistic motion of a charged particle around a dyon in (9 + 1) spacetime is known as the nine-dimensional McIntosh–Cisneros–Zwanziger–Kepler problem. This problem has been solved exactly by the variable-separation method in three different coordinate systems: spherical, parabolic, and prolate spheroidal. In the present study, we establish a relationship between the variable separation and the algebraic structure of SO(10) symmetry. Each of the spherical, parabolic, or prolate spheroidal bases is proved to be a set of eigenfunctions of a corresponding nonuplet of algebraically independent integrals of motion. This finding also helps us establish connections between the bases by the algebraic method. This connection, in turn, allows calculating complicated integrals of confluent Heun, generalized Laguerre, and generalized Jacobi polynomials, which are important in physics and analytics.
Deuteron magnetic resonance study of glyceline deep eutectic solvents: Selective detection of choline and glycerol dynamics
Authors: Hinz Yannik , Böhmer Roland
Published: May 2022

Glyceline, a green solvent considered for various electrochemical applications, represents a multi-component glass former. Viewed from this perspective, the choline cation and the hydrogen bond donor glycerol, the two major constituents forming this deep eutectic solvent, were studied using nuclear magnetic resonance in a selective manner by means of suitably deuteron-labeled isotopologues. Carried out from far above to far below the glass transition temperature, measurements and analyses of the spin-lattice and spin-spin relaxation times reveal that the reorientational dynamics of the components, i.e., of glycerol as well as of chain deuterated choline chloride are slightly different. Possible implications of this finding regarding the hydrogen-bonding pattern in glyceline are discussed. Furthermore, the deuterated methyl groups in choline chloride are exploited as sensitive probes of glyceline’s supercooled and glassy states. Apart from spin relaxometry, a detailed line shape analysis of the CD3 spectra yields valuable insights into the broad intermolecular and intramolecular energy barrier distributions present in this binary mixture.
The low energy spectrum of trapped bosons in the Gross–Pitaevskii regime
Authors: Brennecke Christian
Published: May 2022

Bogoliubov theory {N. N. Bogoliubov, Izv. Akad. Nauk Ser. Fiz. 11, 77 (1947) [J. Phys. (USSR) 11, 23 (1947) (in English)]} provides important predictions for the low energy properties of the weakly interacting Bose gas. Recently, Bogoliubov’s predictions were justified rigorously by Boccato et al. [Acta Math. 222(2), 219–335 (2019)] for translation invariant systems in the Gross–Pitaveskii regime, where N bosons in Λ=[0;1]3⊂R3 interact through a potential whose scattering length is of size N−1. In this article, we review recent results from the work of Brennecke et al. [Ann. Henri Poincaré 23, 1583–1658 (2022)], a joint work with Schlein and Schraven, which extends the analysis for translation invariant systems to systems of bosons in R3 that are trapped by an external potential.
Suprathermal corrections to Bohm–Gross dispersion
Authors: Silveira F. E. M. , Benetti M. H. , Caldas I. L.
Published: May 2022

A detailed resource to data analysis shows that the widely known van Hoven and Derfler–Simonen laboratory results are far from reasonable agreement with the standard Bohm–Gross dispersion relation. We provide an extension of the usual notion of a polytropic index to non-Boltzmann–Gibbs statistics. Such an extension allows for the deduction of an equation of state of charged particles with the basis on the Kappa density distribution. That equation of state, in turn, enables suprathermal corrections to the standard dispersion relation. As a consequence, we prove that the employment of our suprathermal formula is in excellent agreement with the experimental data. Possible further applications of our theory are briefly addressed.
The partially stirred reactor model for combustion closure in large eddy simulations: Physical principles, sub-models for the cell reacting fraction, and open challenges
Authors: Péquin Arthur , Iavarone Salvatore , Malpica Galassi Riccardo , Parente Alessandro
Published: May 2022

For their ability to account for finite-rate chemistry, reactor-based models are well suited Turbulence–Chemistry Interactions (TCI) Sub-Grid Scale (SGS) closures for Large Eddy Simulations (LES). The SGS closure in the Partially Stirred Reactor (PaSR) model relies on the determination of the reacting fraction of each computational cell, whose definition is based on estimates of the characteristic mixing and chemical time scales. Direct Numerical Simulations (DNS) of turbulent combustion can supply key information on TCI for the development, validation, and comparison of combustion models. In particular, a priori testing allows the direct validation of model assumptions. In the present work, an a priori assessment of the PaSR model is conducted. Its ability to reconstruct thermo-chemical quantities of interest is investigated along with model assumptions. Sub-grid quantities are extracted from the DNS to investigate the role of the cell reacting fraction. Various definitions are then proposed to estimate the characteristic chemical timescale in the PaSR model. Modeled chemical source terms and heat release rates are compared against the filtered quantities from DNS data of a two-dimensional, spatially developing, turbulent nonpremixed jet flame with detailed kinetics. The results demonstrate the importance of accounting for the fine structures quantities in the context of reactor-based models. A new formulation of the chemical timescale is proposed and provides improved overall predictions. Several issues are raised in the discussion, representing realistic prospects for further developments of the PaSR model as a SGS combustion closure for LES.
Stochastic evaluation of four-component relativistic second-order many-body perturbation energies: A potentially quadratic-scaling correlation method
Authors: Cruz J. César , Garza Jorge , Yanai Takeshi , Hirata So
Published: May 2022

A second-order many-body perturbation correction to the relativistic Dirac–Hartree–Fock energy is evaluated stochastically by integrating 13-dimensional products of four-component spinors and Coulomb potentials. The integration in the real space of electron coordinates is carried out by the Monte Carlo (MC) method with the Metropolis sampling, whereas the MC integration in the imaginary-time domain is performed by the inverse-cumulative distribution function method. The computational cost to reach a given relative statistical error for spatially compact but heavy molecules is observed to be no worse than cubic and possibly quadratic with the number of electrons or basis functions. This is a vast improvement over the quintic scaling of the conventional, deterministic second-order many-body perturbation method. The algorithm is also easily and efficiently parallelized with 92% strong scalability going from 64 to 4096 processors.
Super-resolution reconstruction of flow field of hydrogen-fueled scramjet under self-ignition conditions
Authors: Guo Mingming , Chen Erda , Tian Ye , Chen Hao , Le Jialing , Zhang Hua , Zhong Fuyu
Published: May 2022

This paper reports experiments on a hydrogen-fueled scramjet performed at different equivalence ratios in a ground pulse combustion wind tunnel with a Mach-2.5 incoming flow. In the non-chemical reaction flow before the fuel was ignited, the flow field was oscillatory, and from the pressure monitor, the oscillation period was 0.07 s and the oscillation amplitude was 0.035 MPa. Schlieren and flame self-luminescence images of the combustor flow were obtained synchronously, and the flow-field structure was stable with the flame concentrated in the shear layer. Deep learning was used to subject the low-resolution combustion flow field to super-resolution analysis to reconstruct a high-resolution flow field. To improve the spatial resolution of the flow field during self-ignition of the hydrogen-fueled scramjet and study the flow mechanism and coupling rule of turbulent fluctuations in the ignition process, a multipath asymmetric residual network (MARN) is proposed based on a single-path super-resolution convolutional neural network (SRCNN) and a residual network model (ResNet_16). The experimental results show that compared with SRCNN and ResNet_16, MARN has the best precision and performance regarding the super-resolution flow field in the self-ignition of hydrogen fuel in terms of the mean peak signal-to-noise ratio, mean structural similarity, and average correlation coefficient as well as being the least complicated. The proposed method offers the possibility of developing lightweight super-resolution models for the flow fields in supersonic combustors; it shows enormous potential for revealing the physical flow of the fuel and air mixture, and it offers accurate forecasts of self-ignition times.
Ultrafast-response and broad-spectrum polarization sensitive photodetector based on Bi1.85In0.15S3 nanowire
Authors: Mo Zhangxun , Zhang Fen , Wang Danyang , Cui Baocheng , Xia Qinglin , Li Bo , He Jun , Zhong Mianzeng
Published: May 2022

Alloying of semiconductors is a good strategy to manipulate their electronic band structures, which can broaden the photoresponse range of the corresponding optoelectronic devices. In addition, building a Schottky diode and improving the crystal quality of the channel semiconductor can improve the photoresponse speed of the optoelectronic device. Here, we report the design and preparation of Bi1.85In0.15S3 nanowires by a facile chemical vapor transport method. The individual Bi1.85In0.15S3 nanowire photodetectors realize excellent photoresponse in a broadband range from solar-blind deep ultraviolet (266 nm) to near-infrared (830 nm), and the obtained maximum external photoresponsivity of 95.99 A/W and detectivity of about 3.52×1011 Jones at 638 nm. Furthermore, the photodetectors also exhibit the ultrafast photoresponse speed with the rise time of 190 ns and the fall time of 180 ns, owing to the high crystal quality and the Schottky contacts between the Au electrodes and nanowires. In addition, the photoresponse of photodetectors is polarization angle sensitive in a broadband range from 266 to 808 nm, and the obtained maximum dichroic ratio is 3.54 at 808 nm, which results from the structural anisotropy of the Bi1.85In0.15S3 crystal. These performances are superior to the reported Bi2S3, In2S3, and other Bi or In sulfide nanowire photodetectors. The results render (BixIn1−x)2S3 photodetectors have significant application potentials in multifunctional optoelectronics and electronics.
Damped perturbations in inviscid shear flows: van Kampen modes and Landau damping
Authors: Polyachenko E. V. , Shukhman I. G.
Published: May 2022

We compare initial value and eigenvalue problems for two-dimensional perturbations of the inviscid shear flow in a channel. Singular solutions, known in plasma physics as van Kampen (vK) modes, are constructed. They form a complete set of eigenfunctions for decomposition of any initial perturbation for stable wavy perturbations. A pair of discrete modes appears to ensure completeness in the unstable case. Expansion coefficients for eigenmodes are found, and equivalence of temporal evolution obtained with the help of the evolutionary equation for vorticity and expansion over eigenmodes is presented. This alternative description of the evolution using vK modes is analogous to ones found earlier in plasma and in stellar dynamics. In particular, for stable wavy perturbations, an initial state decays first exponentially due to Landau damping, then algebraically. It has been established (numerically and analytically) that the final decay law is t−1. Also, we numerically demonstrate that Landau-damped perturbations are not true eigenmodes, but rather a superposition of vK-modes with a real frequency, which does not retain its shape over time. However, solution on contours in the complex plane may exhibit properties of a true eigenmode, that is, decay without changing its spatial form. Energy redistribution between perturbation and the flow, in stable and unstable regimes, is analyzed.
Propagation, mixing, and turbulence characteristics of saline and turbidity currents over rough and permeable/impermeable beds
Authors: He Zhiguo , Han Dongrui , Lin Ying-Tien , Zhu Rui , Yuan Yeping , Jiao Pengcheng
Published: May 2022

A series of constant-flux saline and turbidity current experiments were carried out, focusing on the coupling impact of bed roughness and permeability on current propagation, mixing, and turbulence characteristics. The distinct current propagation phases on RI (rough and impermeable) and RP (rough and permeable) beds are identified, respectively. Experimental results revealed that the intermittently undulating bed surface breaks the strict no-slip boundary, thus, increasing local current velocity near the bed, while its roughness reduces the current peak profile velocity. Interbed pores induced vertical fluid exchange, which synchronously decreases the current peak profile velocity and local velocity near the bed, causes the density profile to no longer follow a monotonous variation trend along with water depth. The larger bed surface roughness or the interbed porosity leads to the smaller upper TKE (turbulent kinetic energy) peak. The lower TKE peak is inversely proportional to the bed surface roughness of the RI beds, while it is proportional to the porosity of the RP bed. A rough bed surface intensifies the asymmetry of the mean velocity distribution around peak velocity resulting in a transfer barrier of turbulent momentum triggered by the interbed pores. On the RP bed, the cross-correlation function based on two-point statistics captures the spikes associated with pore-scale eddies locally, but under the RI condition, it only obtains the logical timescale characterizing the largest eddies of the current. The sediment deposition makes the turbidity current easier to separate from the RP and RI bed than the saline type, causing a consequence of growing the current height.
Optical signatures of the coupling between excitons and charge transfer states in linear molecular aggregates
Authors: Manrho M. , Jansen T. L. C. , Knoester J.
Published: May 2022

Charge Transfer (CT) has enjoyed continuous interest due to increasing experimental control over molecular structures, leading to applications in, for example, photovoltaics and hydrogen production. In this paper, we investigate the effect of CT states on the absorption spectrum of linear molecular aggregates using a scattering matrix technique that allows us to deal with arbitrarily large systems. The presented theory performs well for both strong and weak mixing of exciton and CT states, bridging the gap between previously employed methods, which are applicable in only one of these limits. In experimental spectra, the homogeneous linewidth is often too large to resolve all optically allowed transitions individually, resulting in a characteristic two-peak absorption spectrum in both the weak- and strong-coupling regime. Using the scattering matrix technique, we examine the contributions of free and bound states in detail. We conclude that the skewness of the high-frequency peak may be used as a new way to identify the exciton–CT-state coupling strength.
Hospitalisation costs of primary liver cancer in Australia: evidence from a data-linkage study
Authors: Nguyen Anh Le Tuan , Blizzard Christopher Leigh , Yee Kwang Chien , Campbell Julie A. , Palmer Andrew J. , de Graaff Barbara
Published: May 2022

Objective This study aimed to estimate the public hospital costs associated with primary liver cancer (PLC) in the first and second years following the cancer diagnosis. Methods This study linked administrative datasets of patients diagnosed with PLC in Victoria, Australia, from January 2008 to December 2015. The health system perspective was adopted to estimate the direct healthcare costs associated with PLC, based on inpatient and emergency costs. Costs were estimated for the first 12 months and 12–24 months after the PLC diagnosis and expressed in 2017 Australian dollars (A$). The cost estimated was then extrapolated nationally. The linear mixed model with a Box–Cox transformation of the costs was used to explore the relationship between costs and patients’ sociodemographic and clinical characteristics. Results For the first 12 months, the total and annual per-patient cost was A$211.4 million and A$63 664, respectively. Costs for the subsequent year were A$49.7 million and A$46 751, respectively. Regarding the cost extrapolation to Australia, the total cost was A$137 million for the first 12 months after notification and A$42.6 million for the period from 12 to 24 months. Higher costs per episode of care were mostly associated with older age, hepatocellular carcinoma type of PLC, metropolitan hospitals, and Asian birth region. Conclusion This study showed the public hospital admission and emergency costs associated with PLC and the substantial economic burden this cancer has placed on the Australian health system.
Phase stability of V- based multi-principal element alloys
Authors: Barron Paul J. , Carruthers Alexander W. , Dawson Huw , Rigby Maxwell T. P. , Haigh Sarah , Jones Nick G. , Pickering Ed J.
Published: May 2022

The success of fusion power requires alloys with good mechanical properties and the ability to withstand extreme thermal and irradiation conditions without prohibitive levels of activation or structural degradation. Body-centred cubic multi-principal component alloys, V–Cr–Mn and Ti–V–Cr–Mn have shown promising high-temperature stability at [Formula: see text]. For the alloys to be suitable for use in nuclear fusion reactors, they must be stable across a wide range of temperatures relevant to fusion applications. Here, we assess alloy microstructural stability in these systems following long-term heat treatments at various temperatures. Encouragingly, most of the alloys showed no significant change in microstructure across all temperatures. This contrasts with many other multi-principal component alloys, which develop complex microstructures after exposure to intermediate temperatures.
Joining three aluminium alloy sheets by square clinching process
Authors: Gao Xiaolei , Chen Chao
Published: May 2022

The joining of three-layer AL5052-H32 sheets with the square and round clinching process was studied by experimental means. Two 1.5 mm thick and one 2 mm thick AL5052-H32 sheets with three sheet sequences were joined by the square and round clinching process, respectively. The results showed that the square tools can successfully join three sheets in all three sheet orders, while the round tools can effectively connect three sheets only when the thick sheet is at the bottom. Moreover, the strength of the round joints is generally lower than that of the square joints. The square three-layer joint with the thick top sheet achieves high strength at both two mechanical interlocks.
SAWstitch: exploring self-avoiding walks through hand embroidery
Authors: Brown Christa P , Cook Kalila R , Beales Paul A , Dougan Lorna
Published: May 2022

A self-avoiding walk (SAW) is a sequence of moves on a grid that does not visit the same point more than once. SAWs are used to study how networks form, including social networks, biological networks and computer networks, and have provided inspiration to scientists, artists and designers. Here we describe a collaborative project which aims to deliver public engagement activities that embrace creative thinking to explore SAWs through the medium of hand embroidery. We introduce the physics of SAWs and then present an activity which uses materials from hand embroidery to explore these concepts. Specifically, the activity makes use of a Maker Kit which contains all the materials needed to create SAWs on an embroidery hoop. We evaluate the impact of the Maker Kits and reflect on the opportunities provided by a creativity-led engagement activity for physics teaching and research.
Assessment of Rwandan physics students’ active learning environments: classroom observations
Authors: Ndihokubwayo Kizito , Uwamahoro Jean , Ndayambaje Irénée
Published: May 2022

Science teaching in general and physics teaching in particular often fail to meet the challenges of motivating and engaging learners. Consequently, students do not adequately understand concepts, leading to the poor acquisition of expected practical skills. In response to this need, we conducted a study to document physics teachers’ instructional practices and students’ learning environments in Rwandan secondary schools. We used the Classroom Observation Protocol for Undergraduate STEM to collect data. For three months, we observed 34 geometric optics lessons for nine Senior-4 Physics teachers and 28 physical optics lessons for seven senior-5 Physics teachers. The results indicate that learner-learner active engagement during group work takes 19% of a 2 min time interval. In comparison, learner-teacher active engagement during teacher guide and questioning take 36.8% and 46.5% of a 2 min time interval, respectively. How teachers and students spend time on each classroom activity was analysed, and recommendations for student engagement were also discussed.
Confocal scanning based MUSIC damage imaging algorithm for high guided waves attenuation structures
Authors: Bao Qiao , Wang Qiang , Hu Weiwei
Published: May 2022

Guided waves based structural health monitoring methods are potential for practical applications, since they are sensitive to small damage and could realize large area monitoring. However, guided waves attenuate seriously on some structures, such as carbon fiber composite structures, honeycomb skin structures, thermal protection structures of silicone polymer composites, and so on. Specially, the low signal-to-noise ratio of guided waves, resulting from high attenuation, limits the accuracy of guided waves based methods. In addition, these high attenuation structures are usually anisotropic, which make the propagation velocity related damage imaging methods not accurate. To solve this problem, a novel confocal scanning based multiple signal classification (MUSIC) damage imaging method with array steering vectors correction is proposed in this paper. Confocal scanning is carried out to make the excitation guided waves focused on special positions and MUSIC algorithm is used to synthetic the received guided waves, scattered from damage, to further improve the damage imaging accuracy. At last, an experiment on the carbon fiber composite plate, considered as the high attenuation structure, is carried out to verify this proposed method. Experimental results show that this method can recognize damage imaging within 2° and 18 mm deviations in angle and distance, respectively.
Analyzing Dominant 13.5 and 27 day Periods of Solar Terrestrial Interaction: A New Insight into Solar Cycle Activities
Authors: Syiemlieh Rissnalin , Adhikary Manashee , Panigrahi Prasanta K , Saikia Eeshankur
Published: May 2022

Our analysis presents an explanation of the Sun–Earth coupling mechanism during declining phase of a solar cycle, and how the dominant 13.5 and 27 day periods play roles in the coupling mechanism which led to intense terrestrial magnetic storms during this declining phase compared to the rising phase of a solar cycle. Moreover, it is observed that while the 27 day period gets strongly modulated in the rising phase, the 13.5 day period modulation is more prominent during the declining phase. It is suggested that out of the 27 and 13.5 day periods of Sun–Earth interaction, the preferred period of modulation happens to be the one which is more dominant for the less random or quieter system participating in the coupling. It is reported for the first time that the 13.5 day period is more prominent in the Sun–Earth interaction during the declining phase of a solar cycle, as it is the most dominant period of Earth’s magnetic system, which happens to be more persistent as a dynamical system and hence quieter or more receptive than the Sun.
Defining relative humidity in terms of water activity: III. Relations to dew-point and frost-point temperatures
Authors: Feistel Rainer , Hellmuth Olaf , Lovell-Smith Jeremy
Published: May 2022

Relative humidity (RH) is a fundamental quantity used in many fields of engineering and science, and in particular in meteorology and climate research. Relative fugacity (RF) and, equivalently, relative activity of water vapour in humid air have recently been proposed as a physically well-founded, unambiguous common metrological reference quantity for several conventional but mutually inconsistent definitions of RH. The RF definition is valid is valid under real-gas conditions and above boiling and sublimation temperatures. While differences between RH and RF mostly remain within uncertainties of typical present-day RH measurements, such systematic discrepancies are expected to be of substantial climatological relevance. Consequently, interdisciplinary harmonisation of RH definitions is overdue within the SI framework. Dew-point and frost-point temperatures are preferred measurands in humidity metrology using, for example, chilled-mirror hygrometers. Here, relations are presented for estimating RF from those temperatures, based on equations of state of the 2011 IUGG
6

5

IUGG: International Union of Geodesy and Geophysics, https://iugg.org/.

standard TEOS-10, the ‘international thermodynamic equation of seawater—2010’. Recommendations are given for numerically computing RF using the open-source TEOS-10 SIA library
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SIA Library: Sea-Ice-Air Library of TEOS-10, http://teos-10.org.

. The asymptotic limiting laws of RF for nearly saturated humid air exhibit the familiar form of Clausius–Clapeyron-like equations, despite departing from ideal-gas assumptions. Under various practical conditions, these simple equations may cover the full humidity range with only minor residuals compared to the full numerical TEOS-10 solution for RF.
The geometric theory of phase transitions
Authors: Di Cairano Loris
Published: May 2022

We develop a geometric theory of phase transitions (PTs) for Hamiltonian systems in the microcanonical ensemble. Such a theory allows to rephrase the Bachmann’s classification of PTs for finite-size systems in terms of geometric properties of the energy level sets (ELSs) associated to the Hamiltonian function. Specifically, by defining the microcanonical entropy as the logarithm of the ELS’s volume equipped with a suitable metric tensor, we obtain an exact equivalence between thermodynamics and geometry. In fact, we show that any energy-derivative of the entropy can be associated to a specific combination of geometric curvature structures of the ELSs which, in turn, are well-precise combinations of the potential function derivatives. In so doing, we establish a direct connection between the microscopic description provided by the Hamiltonian and the collective behavior which emerges in a PT. Finally, we also analyze the behavior of the ELSs’ geometry in the thermodynamic limit showing that nonanalyticities of the energy-derivatives of the entropy are caused by nonanalyticities of certain geometric properties of the ELSs around the transition point. We validate the theory studying PTs that occur in the ϕ
4 and Ginzburg–Landau-like models.
Universal amplitudes ratios for critical aging via functional renormalization group
Authors: Vodret Michele , Chiocchetta Alessio , Gambassi Andrea
Published: May 2022

We discuss how to calculate non-equilibrium universal amplitude ratios in the functional renormalization group approach, extending its applicability. In particular, we focus on the critical relaxation of the Ising model with non-conserved dynamics (model A) and calculate the universal amplitude ratio associated with the fluctuation–dissipation ratio of the order parameter, considering a critical quench from a high-temperature initial condition. Our predictions turn out to be in good agreement with previous perturbative renormalization-group calculations and Monte Carlo simulations.