bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the performance of tuned mass dampers by considering geometric nonlinear effects in an integrated identification-control approach
Authors: Ghaderi Pedram , Gholam Samaneh
Published: November 2023

Tuned mass damper (TMD) is considered a common and effective device in structural control during catastrophic events such as earthquakes. This paper presents a promising method to improve the performance of TMD on vibratory structures with unknown parameters, by addressing the geometric nonlinear effects in an integrated identification-control approach. To evaluate the efficiency of this method, the reductions of the maximum displacement, shear force, acceleration of the top floor, and the mechanical energy of the structure are considered as performance indicators. Firstly, a proper relationship based on stiffness reduction is provided to consider geometric nonlinearity and perform second-order analysis. Secondly, the virtual synchronization method (VSM) is employed to identify the unknown parameters of the structures including stiffness and damping coefficients. Subsequently, an appropriate algorithm is developed to represent the integrated identification-control approach which utilizes the current properties of structures identified by VSM, for tuning the TMD. Afterward, these methods are employed to determine the circumstances where second-order analysis is preferable to first-order analysis, considering performance indicator differences. These circumstances deal with three variables including the characteristics of earthquakes and structures as well as the level of damage. To incorporate the first two variables, studies are conducted on several structures with different periods subjected to ten earthquakes with various frequency contents. Furthermore, for inclusion of the last variable, structures experience different levels of damage. As a result, this study determines the ranges based on the three mentioned variables wherein incorporating geometric nonlinear effects improves the performance of TMD and should be considered in structural analysis. Furthermore, similar relationships are provided for the assessment of the performance of the VSM. Finally, a study is provided to validate the performance of the integrated identification-control approach.
Coexistence of Competing Microbial Strains under Twofold Environmental Variability and Demographic Fluctuations
Authors: Asker Matthew , Hernández-Navarro Lluís , Rucklidge Alastair M , Mobilia Mauro
Published: November 2023

Microbial populations generally evolve in volatile environments, under conditions fluctuating between harsh and mild, e.g. as the result of sudden changes in toxin concentration or nutrient abundance. Environmental variability (EV) thus shapes the long-time population dynamics, notably by influencing the ability of different strains of microorganisms to coexist. Inspired by the evolution of antimicrobial resistance, we study the dynamics of a community consisting of two competing strains subject to twofold EV. The level of toxin varies in time, favouring the growth of one strain under low drug concentration and the other strain when the toxin level is high. We also model time-changing resource abundance by a randomly switching carrying capacity that drives the fluctuating size of the community. While one strain dominates in a static environment, we show that species coexistence is possible in the presence of EV. By computational and analytical means, we determine the environmental conditions under which long-lived coexistence is possible and when it is almost certain. Notably, we study the circumstances under which environmental and demographic fluctuations promote, or hinder, the strains coexistence. We also determine how the make-up of the coexistence phase and the average abundance of each strain depend on the EV.
Predator–prey power laws: trophic interactions give rise to scale-invariant ecosystems
Authors: Salahshour Mohammad
Published: November 2023

Scaling laws and power-law distributions are ubiquitous in ecological systems. However, it is not clear what factors give rise to such universal regularities. Here, I show scaling laws are a simple consequence of scale-invariant distributions, and both result from simple commonalities of diverse ecosystems. I introduce a simple model of predator–prey interactions in which predators and prey move on a two-dimensional space in search of resources that they use to survive and reproduce. As primary resources increase, the food web exhibits a series of transitions to phases with equilibrium dynamics and top-down control of the food web, non-equilibrium dynamics with bottom-up control, and unstable dynamics exhibiting the paradox of enrichment. The model shows resource heterogeneity can solve the paradox of enrichment and ensure the stability of ecosystems. Scale-invariant spatial distribution of prey and predators and a surprisingly rich set of scaling laws, including predator–prey and Taylor’s power laws, appear in the non-equilibrium phase. The model predicts both Taylor’s power law and predator–prey power law can be extended to a rich set of fluctuation scaling laws governing the fluctuation of predator’s and prey’s densities and growth. A mathematical theory suggests scaling laws result from the scale-invariance of the spatial distribution of prey and predators.
Dynamically tunable multiple plasmon-induced transparency effect based on monolayer graphene structure system with rectangular defect cavities
Authors: Wang Boyun , Yang Jie , Zeng Qingdong , Li Geng , Yu Huaqing , Chen Fang , Yu Chunchao , Wang Tao
Published: November 2023

In this article, a dynamically tunable multiple plasmon-induced transparency (PIT) effect in monolayer graphene structure system with rectangular defect cavities is investigated both theoretically and numerically. Because the graphene of our structure exists in a continuous form, the Fermi level of the graphene can be dynamically tuned by simply applying a bias voltage. The expressions of the theoretical transmittance are correctly deduced, and the fitting theoretical results are very consistent with the numerical simulation data. When the Fermi level of the graphene is increased from 0.8 eV to 1.2 eV, the group index of the dual-PIT system is controlled between 383 and 766. Alternatively, the group index of the triple-PIT system is maintained between 445 and 812. Moreover, the maximum group index can reach 812 at 1.2 eV, which shows that it can be designed as an excellent slow light device. Therefore, the proposed structures and results may provide strong guidance towards multichannel optical filters, dynamically tunable and excellent slow light and light storage devices.
Tempered fractional diffusion in comb-like structures with numerical investigation
Authors: Mokhtar Hefny Mohamed , Tawfik Ashraf M
Published: November 2023

This paper presents two models for describing anomalous transport in comb-like structures. First, we analytically solve the tempered fractional diffusion model using the Laplace-Fourier technique. The probability distributions along the backbone (x-axis) and branches (y-axis) are represented by the M-Wright and Fox’s H functions. The probability distributions are illustrated according to the order of the time-fractional derivative α and the so-called tempered parameter λ. Additionally, we determine the mean square displacement to classify the degree of diffusivity in the comb structure based on the values of the time-fractional and tempered orders. Second, we introduce a power-law time-dependent diffusion coefficient as an extension of the comb-like models and investigate the solution of via numerical simulation. Then, we explore the connection between the presence of a time-dependent diffusion coefficient and anomalous transport based on the particle density and mean square displacement.
Sliding wear study of WC-10Co4Cr clad on SS-316 using microwave energy
Authors: Singh Paramjit , Goyal Deepak Kumar , Bansal Amit
Published: November 2023

The current study comprises the changing surface morphology of austenitic stainless steel (SS-316) with WC-10Co4Cr powder using an affordable microwave route. The surface modification was achieved by utilizing a microwave apparatus (power: 1.2 kW; frequency: 2.45 GHz). The x-ray diffraction (XRD) study reveals the presence of various carbide phases in the deposited clad layer. The scanning electron microscope (SEM) examination reveals the unequally dispersed reinforced skeleton carbide in a metal-based matrix with an average porosity of less than 1%. The deposits exhibit significantly higher hardness than that of the SS-316. A pin-on-disc tribometer was utilized to assess the dry sliding wear performance of deposits. The results revealed that the deposits exhibited better wear resistance than the SS-316 substrate due to the presence of reinforced hard carbides in a tougher metal-based matrix. The improvement in microhardness also leads to enhancement in the wear resistance of the deposits. The loss of material from the deposit surfaces during sliding was primarily due to micro-cutting and rupturing of the unstable tribofilm layer.
Tailoring gas sensing properties of WS2 monolayer via Nb and Co embedding for highly sensitive and selective detection of HCN and H2S gases: a first principle study
Authors: Rhrissi I , Bouhmouche A , Arba Y , Saeedi A M , Moubah R
Published: November 2023

We report on the adsorption performances of HCN, H2S, HF, and H2 gases on Nb and Co embedded WS2 monolayer using density functional theory calculations. The adsorption configurations, adsorption energy, charge transfer, density of state, band structure, and recovery time were studied to evaluate the possible tailoring of gas sensing properties to improve sensitivity and selectivity of the WS2 monolayer. The results show that HCN exhibits better adsorption on the Nb-embedded WS2 with an adsorption energy of −1.09 eV and charge transfer of −0.18 e, whereas H2S shows superior adsorption on the Co-embedded WS2 with an adsorption energy of −1.1 eV and charge transfer of 0.23 e. Better sensitivity and selectivity were recorded for the adsorption of the HCN and H2S on the Nb and Co-embedded WS2 monolayer respectively. At 398 K, the recovery times for the two sensing systems are 54 s and 61 s for Nb-embedded WS2 with HCN and Co-embedded WS2 with H2S respectively making them suitable for gas sensing applications. The study reveals the promising capabilities of Nb-embedded WS2 and Co-embedded WS2 in detecting HCN and H2S, respectively. In addition, it thoroughly investigates the influence of surface modifications on the characteristics of gas sensors.
Atomic-scale study of linear reciprocating friction of TCP/γ phase in nickel-based single crystal alloy
Authors: Chen Weihua , Sun Yuhang , Feng Xingzhi , Liu Yanjie , Zheng Min , Wei Xingchun , Zhu Zongxiao
Published: November 2023

In order to systematically investigate the role of TCP (topologically close-packed) phases in the fretting wear process of nickel-based single crystal alloys (NBSC), this study employed molecular dynamics to conduct comparative analyses of mechanical properties, atomic displacements, wear depth, defects, dislocation density, and the influence of temperature under constant load on the friction process in material wear. The research revealed that during the repetitive friction process, the friction force exhibited a peak at the extreme positions of reciprocating friction on the workpieces, and this peak increased with the number of friction cycles. The dislocation density in the worn area increased, resulting in hardening, and the removal rate of material decreased. At the initial stages of friction, the presence of interfaces notably hindered the transfer of temperature, defects, and atomic displacements in the workpiece, and this inhibitory effect weakened with an increasing number of friction cycles. The TCP phases experienced stratification due to the overall deformation they underwent. Furthermore, as the relaxation temperature increased, the workpiece exhibited enhanced plastic deformation capacity, an increase in dislocation density, and adhesion between abrasive particles and the grinding ball occurred.
Mechanical properties prediction of ductile iron with spherical graphite using multi-scale finite element model
Authors: Alizadeh Mohammad Hosein , Ajri Masoud , Maleki Vahid Arab
Published: November 2023

In this paper, using the multi-scale finite element method, the effect of graphite particles on the mechanical behavior of ductile iron has been investigated under tensile loading. For this purpose, taking into account the spherical geometric shape of the graphite phase and considering a specific volume fraction, these spheres are randomly placed in the whole body and a two-component composite material is created. As a next step, a micromechanical model of these materials is developed by defining the mechanical properties of the matrix and graphites as well as their interfaces. The mechanical properties of the matrix are simulated using the Ramberg-Osgood elastic-plastic model. By simulation in ABAQUS software and using nonlinear dynamic analysis, the effects of volume percentages and adhesion of graphite particles with matrix on the direct tensile load-displacement behavior of ductile iron were investigated. The results of experimental tests were used to verify the results of the numerical model. The weight percentage of graphite particles has a significant effect on the tensile strength and elastic modulus of these cast irons. The results show that with the increase in the amount of graphite particles, the tensile strength of cast iron increases up to a certain value and then reverses. With 21% graphite particles, the maximum tensile strength of ductile iron is 601 MPa. Compared with a pure sample of cast iron, the tensile strength increases by approximately 13.4% for this weight percentage of graphite particles.
Highly sensitive temperature sensor using nested hollow-core anti-resonant fibers
Authors: Yue-Yu Xiao , Yan-Xiang Lai , Rui-Ming Yao
Published: November 2023

A highly sensitive temperature sensor based on composite nested negative curvature hollow-core fiber is proposed. Three resonant tubes are nested inside the cladding tubes to induce a resonant coupling between the fundamental core mode and the dielectric mode of the nested resonant tube. Three glass-sheet conjoined nested tubes are introduced to suppress the comparatively low loss higher-order mode LP02. All the air-holes are filled with temperature-sensitive liquid of ethanol. As the temperature changes, the resonant dip in the transmission spectrum corresponding to the coupling will shift. Numerical simulation results indicate that the temperature sensitivity is 3.36 nm °C−1 in the range of 20 °C–40 °C. Since there is no need of any special post-processing, such as selective infiltration or material coating for the sensors proposed, the sensor provides a promising mechanism for the optical fiber temperature sensing.
Magnetic field regression using artificial neural networks for cold atom experiments
Authors: Chen 陈 Ziting 子霆 , Wong 黃 Kin To 建陶 , Seo Bojeong , Huang 黄 Mingchen 明琛 , Parit Mithilesh K. , He 何 Yifei 逸飞 , Zhen 甄 Haoting 浩廷 , Li Jensen , Jo Gyu-Boong
Published: November 2023

Accurately measuring magnetic fields is essential for magnetic-field sensitive experiments in areas like atomic, molecular, and optical physics, condensed matter experiments, and other areas. However, since many experiments are often conducted in an isolated environment that is inaccessible to experimentalists, it can be challenging to accurately determine the magnetic field at the target location. Here, we propose an efficient method for detecting magnetic fields with the assistance of an artificial neural network (NN). Instead of measuring the magnetic field directly at the desired location, we detect fields at several surrounding positions, and a trained NN can accurately predict the magnetic field at the target location. After training, we achieve a below 0.3% relative prediction error of magnetic field magnitude at the center of the vacuum chamber, and successfully apply this method to our erbium quantum gas apparatus for accurate calibration of magnetic field and long-term monitoring of environmental stray magnetic field. The demonstrated approach significantly simplifies the process of determining magnetic fields in isolated environments and can be applied to various research fields across a wide range of magnetic field magnitudes.
An ECM-mimicking assembled gelatin/hyaluronic acid hydrogel with antibacterial and radical scavenging functions for accelerating open wound healing
Authors: Ma Xuebin , Ning Wenli , Geng Yiming , Shao Huarong , Liu Yang , Liu Fei , Zhang Daizhou , Chi Bo , Hou Yali , Fu Xiao
Published: November 2023

A multifunctional hydrogel dressing with hemostatic, antibacterial, and reactive oxygen species (ROS)-removing properties is highly desirable for the clinical treatment of open wounds. Although many wound dressings have been prepared, the modification of polymers is often involved in the preparation process, and the uncertainty of biological safety and stability of modified polymers hinders the clinical application of products. In this study, inspired by the composition and crosslinking pattern of extracellular matrix (ECM), a deeply ECM-mimicking multifunctional hydrogel dressing is created. Tannic acid (TA) and poly-ϵ-lysine (EPL) are added into a gelatin/hyaluronic acid (Gel/HA) matrix, and a stable hydrogel is formed due to the formation of the triple helix bundles of gelatin and hydrogen bonds between polymers. The introduction of TA and EPL endows the ECM-mimicking hydrogel with stable rheological properties, as well as antibacterial and hemostatic functions. The as-produced hydrogels have suitable swelling ratio, enzyme degradability, and good biocompatibility. In addition, it also shows a significant ability to eliminate ROS, which is confirmed by the elimination of 2,2-diphenyl-1-picrylhydrazyl free radical. Full-thickness skin wound repair experiment and histological analysis of the healing site in mice demonstrate that the developed ECM-mimicking Gel/HA hydrogels have a prominent effect on ECM formation and promotion of wound closure. Taken together, these findings suggest that the multifunctional hydrogels deeply mimicking the ECM are promising candidates for the clinical treatment of open wounds.
Kinetic equilibrium reconstruction with internal safety factor profile constraints on EAST tokamak
Authors: FAN 樊 Haochen 皓尘 , LI 李 Guoqiang 国强 , QIAN 钱 Jinping 金平 , ZHANG 张 Xuexi 学习 , WU 邬 Xiaohe 潇河 , CHU 储 Yuqi 宇奇 , ZHU 朱 Xiang 翔 , LIAN 连 Hui 辉 , LIU 刘 Haiqing 海庆 , LYU 吕 Bo 波 , JIN 金 Yifei 仡飞 , ZANG 臧 Qing 庆 , HUANG 黄 Jia 佳
Published: November 2023

Reconstruction of plasma equilibrium plays an important role in the analysis and simulation of plasma experiments. The kinetic equilibrium reconstruction with pressure and edge current constraints has been employed on EAST tokamak. However, the internal safety factor (q) profile is not accurate. This paper proposes a new way of incorporating q profile constraints into kinetic equilibrium reconstruction. The q profile is yielded from the Polarimeter Interferometer (POINT) reconstruction. Virtual probes containing information on q profile constraints are added to inputs of the kinetic equilibrium reconstruction program to obtain the final equilibrium. The new equilibrium produces a more accurate internal q profile. This improved method would help analyze EAST experiments.
Final results of the first phase of the PROTO-SPHERA experiment: obtainment of the full current stable screw pinch and first evidences of the jet + torus combined plasma configuration
Authors: MICOZZI Paolo , ALLADIO Franco , MANCUSO Alessandro , ZANZA Vincenzo , APRUZZESE Gerarda , BOMBARDA Francesca , BONCAGNI Luca , BURATTI Paolo , FILIPPI Francesco , TEKA Giuseppe GALATOLA , GIAMMANCO Francesco , GIOVANNOZZI Edmondo , GROSSO Andrea , IAFRATI Matteo , LAMPASI Alessandro , LAZIC Violeta , MAGAGNINO Simone , MANNORI Simone , MARSILI Paolo , PIERGOTTI Valerio , ROCCHI Giuliano , SIBIO Alessandro , TILIA Benedetto , TUDISCO Onofrio
Published: November 2023

In astrophysics, the boundary conditions for plasma phenomena are provided by nature and the astronomer faces the problem of understanding them from a variety of observations [Hester J J et al 1996 Astrophys. J.
456 225], on the other hand, in laboratory plasma experiments the electromagnetic boundary conditions become a major problem in the set-up of the machine that produces the plasma, an issue that has to be investigated step by step and to be modified and adapted with great patience, in particular in the case of an innovative plasma confinement experiment. The PROTO-SPHERA machine [Alladio F et al 2006 Nucl. Fusion
46 S613] is a magnetic confinement experiment, that emulates in the laboratory the jet + torus plasma configurations often observed in astrophysics: an inner magnetized jet of plasma centered on the (approximate) axis of symmetry and surrounded by a magnetized plasma torus orthogonal to this jet. The PROTO-SPHERA plasma is simply connected, i.e., no metal current conducting rod is linked to the plasma torus, while instead it is the inner magnetized plasma jet (in the following always called the plasma centerpost) that is linked to the torus. It is mandatory that no spurious plasma current path modifies the optimal shape of the plasma centerpost. Moreover, as the plasma torus is produced and sustained, in absence of any applied inductive electric field, by the inner plasma centerpost through magnetic reconnections [Taylor J B and Turner M F 1989 Nucl. Fusion
29 219], it is required as well that spurious current paths do not surround the torus on its outboard, in order not to lower the efficiency of the magnetic reconnections that maintain the plasma torus at the expense of the plasma centerpost. Boundary conditions have been corrected, up to the point that the first sustainment in steady state has been achieved for the combined plasma.
Experimental study on the effect of H2O and O2 on the degradation of SF6 by pulsed dielectric barrier discharge
Authors: LI 李 Yalong 亚龙 , WAN 万 Kun 昆 , WANG 王 Yufei 宇非 , ZHANG 张 Xiaoxing 晓星 , YANG 杨 Zhaodi 照迪 , FU 傅 Mingli 明利 , ZHUO 卓 Ran 然 , WANG 王 Dibo 邸博
Published: November 2023

SF6 has excellent insulation performance and arc extinguishing ability, and is widely used in the power industry. However, its global warming potential is about 23,500 times that of CO2, it can exist stably in the atmosphere, it is not easily degradable and is of great potential harm to the environment. Based on pulsed dielectric barrier discharge plasma technology, the effects of H2O and O2 on the degradation of SF6 were studied. Studies have shown that H2O can effectively promote the decomposition of SF6 and improve its degradation rate and energy efficiency of degradation. Under the action of a pulse input voltage and input frequency of 15 kV and 15 kHz, respectively, when H2O is added alone the effect of 1% H2O is the best, and the rate and energy efficiency of degradation of SF6 reach their maximum values, which are 91.9% and 8.25 g kWh−1, respectively. The synergistic effect of H2O and O2 on the degradation of SF6 was similar to that of H2O. When the concentration of H2O and O2 was 1%, the system obtained the best rate and energy efficiency of degradation, namely 89.7% and 8.05 g kWh−1, respectively. At the same time, different external gases exhibit different capabilities to regulate decomposition products. The addition of H2O can effectively improve the selectivity of SO2. Under the synergistic effect of H2O and O2, with increase in O2 concentration the degradation products gradually transformed into SO2F2. From the perspective of harmless treatment of the degradation products of SF6, the addition of O2 during the SF6 degradation process should be avoided.
Dynamic propagation velocity of a positive streamer in a 3 m air gap under lightning impulse voltage
Authors: LI 李 Zhiwei 志伟 , LEI 雷 Ting 挺 , SU 苏 Yu 宇 , YAO 姚 Xiuyuan 修远 , YANG 杨 Bingxue 冰雪 , LIU 刘 Delong 德龙 , LV 律 Fangcheng 方成 , DING 丁 Yujian 玉剑
Published: November 2023

Streamers represent an important stage in the initiation of gap discharge. In this work, we used an eight-frame intensified charge-coupled device camera to capture the streamer development process when a lightning impulse voltage of 95%–100% U
50% was applied in a 3 m rod–plate gap and the streamer velocity was analyzed. Analysis of the observations shows that streamer velocity can be defined by three stages: rapid velocity decline (stage 1), rapid velocity rise (stage 2) and slow velocity decline (stage 3). The effects of electrode shape, applied voltage and gap breakdown or withstanding on streamer velocity were analyzed. The electrode with a larger radius of curvature will result in a higher initial velocity, and a higher voltage amplitude will cause the streamer to propagate faster at stage 3. Gap withstanding or breakdown has no obvious effect on streamer velocity. In addition, the experimental results are compared with previous results and the statistical characteristics of the primary streamer discharge are discussed.
Performance of pulsed plasma thruster at low discharge energy
Authors: LEE 李 Hong Chun 鸿俊 , LIM 林 Chie Haw 泽豪 , WOO 胡 Haw Jiunn 浩俊 , GOH 吴 Boon Tong 文东 , CHIN 陈 Oi Hoong 爱虹 , TOU 杜 Teck Yong 德扬
Published: November 2023

As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster (PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at 2 J or more of discharge energy. In this work, the performance of a PPT with a side-fed, tongue-flared electrode configuration operated within a lower discharge energy range of 0.5‒2.5 J has been investigated. Ablation and charring of the polytetrafluoroethylene propellant surface were analyzed through field-effect scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy. When the discharge energy fell below 2 J, inconsistencies occurred in the specific impulse and the thrust efficiency due to the measurement of the low mass bit. At energy

2 J, the performance parameters are compared with other PPT systems of similar configuration and discussed in depth.
Laser-induced plasma formation in water with up to 400 mJ double-pulse LIBS
Authors: HENKEL Marion , SIEMENS Michelle , METHLING Ralf , EMDE Benjamin , HERMSDORF Jörg , FRANKE Steffen , GONZALEZ Diego
Published: November 2023

Double-pulse LIBS is a promising technique for deep-sea applications. LIBS measurements in shallow water with up to 400 mJ each pulse were done to select laser parameters which promote optimized spectral line emission from plasma even at elevated pressures, where line broadening until loss of most of the spectral information can occur. Optical emission spectroscopy, using a Czerny-Turner spectrometer, has been applied to investigate the dependence of the emitted radiation on laser parameters and hydrostatic pressure. It has been found, that higher laser pulse energies, especially with short pulse delay as required in high water pressure, can also have an adverse effect on the measured spectrum.
Theoretically predicting the solubility of polydisperse polymers using Flory–Huggins theory
Authors: van Leuken Stijn H M , van Benthem Rolf A T M , Tuinier Remco , Vis Mark
Published: November 2023

Polydispersity affects physical properties of polymeric materials, such as solubility in solvents. Most biobased, synthetic, recycled, mixed, copolymerized, and self-assembled polymers vary in size and chemical structure. Using solvent fractionation, this variety in molecular features can be reduced and a selection of the sizes and molecular features of the polymers can be made. The significant chemical and physical dispersity of these polymers, however, complicates theoretical solubility predictions. A theoretical description of the fractionation process can guide experiments and material design. During solvent fractioning of polymers, a part of the polydisperse distribution of the polymers dissolves. To describe this process, this paper presents a theoretical tool using Flory–Huggins theory combined with molecular mass distributions and distributions in the number of functional groups. This paper quantifies how chemical and physical polydispersity of polymers affects their solubility. Comparison of theoretical predictions with experimental measurements of lignin in a mixture of solvents shows that multiple molecular features can be described well using a single set of parameters, giving a tool to theoretically predict the selective solubility of polymers.
Correlation between charpy-V notch impact energy and KJIC of ferrite ductile iron in the transition-temperature region
Authors: Wang Zekun , Wang Wenjie , Sun Zhiren , Zhou Zhou , Zhang Kai , Ma Li , Wang Yuwei , Yang Sen , Huang Zherong , Wang Kaikun
Published: November 2023

Fracture toughness is an important index for the structural integrity assessment of ductile iron spent fuel transportation casks. Fracture toughness tests require a long test period, high cost, and difficult operation. Therefore, the Charpy V-notch impact energy value (KV) is considered to predict fracture toughness (KJIC).In this study, Charpy V-notch impact tests(−80 °C, −60 °C, −40 °C, −20 °C, 0 °C, 20 °C, 40 °C, 60 °C, 80 °C) and fracture toughness tests(−60 °C, −40 °C, −20 °C, 0 °C, 20 °C) of ferrite ductile iron(FDI) were carried out. A KJIC-KV model for FDI in the transition temperature region was proposed, taking into consideration the influence of test temperature(T) and yield strength(σ
YS), then the proposed model was compared to the KIC-KV empirical equations of steel in the transition-temperature region, using the test data of FDI. The results indicate that the KJIC-KV model proposed in this work is more accurate and applicable for predicting fracture toughness values in the transition-temperature region than others, the residual between the estimated value of the KJIC-KV correlation model (KJIC-E) and the experimental value of KJIC(KJIC-T) was less than 4.1 MPa·m0.5, and the error was less than 5%.
Existence of the solutions to the Brocard–Ramanujan problem for norm forms
Authors: Takeda Wataru
Published: November 2023

The Brocard–Ramanujan problem, which is an unsolved problem in number theory, is to find integer solutions

(
x
,
ℓ
)

(x,\ell )

of

x
2

−
1
=
ℓ
!

x^2-1=\ell !

. Many analogs of this problem are currently being considered. As one example, it is known that there are at most only finitely many algebraic integer solutions

(
x
,
ℓ
)

(x, \ell )

, up to a unit factor, to the equations

N
K

(
x
)
=
ℓ
!

N_K(x) = \ell !

, where

N
K

N_K

are the norms of number fields

K

/

Q

K/\mathbf Q

. In this paper, we construct infinitely many number fields

K
K

such that

N
K

(
x
)
=
ℓ
!

N_K(x) = \ell !

has at least

22
22

solutions for positive integers

ℓ
\ell

.
A machine learning model for the prediction of unhealthy alcohol use among women of childbearing age in Alabama
Authors: Johnson Karen A , McDaniel Justin T , Okine Joana , Graham Heather K , Robertson Ellen T , McIntosh Shanna , Wallace Juliane , Albright David L
Published: November 2023

Introduction: This study utilizes a machine learning model to predict unhealthy alcohol use treatment levels among women of childbearing age. Methods: In this cross-sectional study, women of childbearing age (n = 2397) were screened for alcohol use over a 2-year period as part of the AL-SBIRT (screening, brief intervention, and referral to treatment in Alabama) program in three healthcare settings across Alabama for unhealthy alcohol use severity and depression. A support vector machine learning model was estimated to predict unhealthy alcohol use scores based on depression score and age. Results: The machine learning model was effective in predicting no intervention among patients with lower Patient Health Questionnaire (PHQ)-2 scores of any age, but a brief intervention among younger patients (aged 18–27 years) with PHQ-2 scores >3 and a referral to treatment for unhealthy alcohol use among older patients (between the ages of 25 and 50) with PHQ-2 scores >4. Conclusions: The machine learning model can be an effective tool in predicting unhealthy alcohol use treatment levels and approaches.
Biological inhibition of denitrification (BDI): an early plant strategy for Fallopia × bohemica seedling development
Authors: Cantarel Amélie A M , Signoret Aymeric , Gervaix Jonathan , Beligon Chiquitta , Béraud Cédric , Boisselet Christelle , Creuzé des Châtelliers Charline , Defour Pauline , Delort Abigaïl , Lacroix Elise , Lobreau Clément , Louvez Enzo , Marais Coralie , Simonin Marie , Piola Florence
Published: November 2023

Background and Aims

The successful plant Fallopia × bohemica presents interesting capacities for control of the soil nitrogen cycle at the adult stage, termed biological inhibition of denitrification (BDI). The BDI strategy allows the plant, via the production of secondary metabolites (procyanidins), to compete with the denitrifying microbial community and to divert nitrate from the soil for its benefit. In this study, we analysed whether seedlings of F. × bohemica can implement BDI at the seedling stage. We also determined whether soil nitrogen availability influences the implementation of BDI and seedling growth.

Methods

We sowed achenes of F. × bohemica in soils representing a nitrogen gradient (six treatments) and harvested seedlings after 20 or 40 days of growth. The denitrification and related microbial communities (i.e. functional gene abundances of nirK and nirS), soil parameters (nitrate content and humidity) and plant performance (biomass, growth and root morphology) were determined.

Key Results

On soil without addition of nitrogen, BDI was observed after 20 days of growth, whereas a stimulation of denitrification was found after 40 days. The increase of soil N content had few effects on the activity and structure of the soil denitrifying community and on the plant biomasses or the relative growth rates. Correlations between plant and microbial parameters were observed after 20 days of growth, reflecting early and strong chemical interactions between plants and the denitrifying community, which decreased with plant growth after 40 days.

Conclusions

This study shows that an early BDI enhances the efficiency of nitrogen acquisition in the first weeks of growth, allowing for a conservative root strategy after 40 days. This switch to a conservative strategy involved resource storage, an altered allocation to above- and below-ground parts and an investment in fine roots. It now seems clear that this storage strategy starts at a very young age with early establishment of BDI, giving this clonal plant exceptional capacities for storage and multiplication.
The relationship between wing morphology and foraging guilds: exploring the evolution of wing ecomorphs in bats
Authors: Ospina-Garcés Sandra M , Zamora-Gutierrez Veronica , Lara-Delgado Juan Manuel , Morelos-Martínez Mercedes , Ávila-Flores Rafael , Kurali Anikó , Ortega Jorge , Selem-Salas Celia Isela , MacSwiney G. M Cristina
Published: November 2023

Different aspects of foraging strategies in bats have been studied to understand the evolution of flight in mammals. General descriptors of wing morphology associated with flight performance, such as aspect ratio and wing loading, allowed us to describe ecomorphs determined by the dietary preferences of bat species. However, the role of wing shape divergence in the evolution of bat foraging strategies remains little explored. We adopted a two-dimensional geometric morphometric approach to quantify the wing shape and size variation explained by phylogenetic relatedness (families) and to evaluate the covariance between foraging guilds and flight descriptors based on phylogenetic comparative methods in 69 Neotropical bat species. We tested whether wing morphology represents a reliable marker of the foraging guild, and we explored the rate of shape evolution among foraging guilds to describe divergent trends that could explain the morphological and ecological diversification. Our results suggest that the earliest bat ancestor was an aerial forager occupying the edge space, which is congruent with the observed evolution of wing shape from an edge space wing morphology. The relationship between wing shape and foraging space defines wing ecomorphs, which probably evolved early in bat ancestors; a process other than convergence could explain this association.
Discretion and Strategies for Investigating Child Abuse: Social Workers’ Conceptions of Child Abuse Investigations and Police Reporting
Authors: Quarles van Ufford Sara , Heimer Maria , Schön Ulla-Karin , Linell Hanna
Published: November 2023

Understanding the capacity of child welfare (CW) organisations to deal with child abuse is complex, and dependent on the specific CW context. Sweden occupies a unique position in trying to balance high demands for CW and protection with a strong family support focus, which carries a risk of overlooking children who need protection. Drawing on an understanding of social service organisations as street-level bureaucracies, this article explores discretion in child abuse cases by examining conditions affecting discretion and strategies for investigating child abuse, including police reporting. Thematic analysis of interviews with Swedish supervising social workers showed that staff’s conceptions of the CW system influenced the exercise of discretion, leading to different strategies for dealing with child abuse. This resulted in different practices and potentially unequal access to child protection and support, highlighting the wide margin of discretion. This article concludes that the interplay between knowledge and governance is central to equal child protection. This article contributes to the discussion of discretion in CW organisations by underlining the importance of being particularly vigilant about discretion when both children and parents are considered clients, as the child risks being lost as a subject with individual needs and rights.
Immunotherapy in the context of immune-specialized environment of brain metastases
Authors: James Fiona , Lorger Mihaela
Published: November 2023

Brain metastases (BrM) develop in 20–40% of patients with advanced cancer. They mainly originate from lung cancer, melanoma, breast cancer, and renal cell carcinoma, and are associated with a poor prognosis. While patients with BrM traditionally lack effective treatment options, immunotherapy is increasingly gaining in importance in this group of patients, with clinical trials in the past decade demonstrating the efficacy and safety of immune checkpoint blockade in BrM originating from specific tumor types, foremost melanoma. The brain is an immune-specialized environment with several unique molecular, cellular, and anatomical features that affect immune responses, including those against tumors. In this review we discuss the potential role that some of these unique characteristics may play in the efficacy of immunotherapy, mainly focusing on the lymphatic drainage in the brain and the role of systemic anti-tumor immunity that develops due to the presence of concurrent extracranial disease in addition to BrM.
RETRACTED: Exercise pulmonary hypertension by the mPAP/CO slope in primary mitral regurgitation
Authors: Dhont Sebastiaan , Stassen Jan , Herbots Lieven , Hoedemakers Sarah , Bekhuis Youri , Jasaityte Ruta , Stroobants Sarah , Petit Thibault , Bakelants Elise , Falter Maarten , Ferreira Sara Moura , Claessen Guido , Nijst Petra , Vandervoort Pieter M , Bertrand Philippe B , Verwerft Jan
Published: November 2023

This article has been retracted. Please see: https://doi.org/10.1093/ehjci/jeaf016
Lack of incremental value of three-dimensional measurement in assessing invasiveness for lung cancer
Authors: Wang Meng-Min , Li Jia-Qi , Dou Shi-Hua , Li Hong-Ji , Qiu Zhen-Bin , Zhang Chao , Yang Xiong-Wen , Zhang Jia-Tao , Qiu Xin-Hua , Xie Hong-Sheng , Tang Wen-Fang , Cheng Mei-Ling , Yan Hong-Hong , Yang Xue-Ning , Wu Yi-Long , Zhang Xue-Gong , Yang Lin , Zhong Wen-Zhao
Published: November 2023

OBJECTIVES

The aim of this study was to evaluate the performance of consolidation-to-tumour ratio (CTR) and the radiomic models in two- and three-dimensional modalities for assessing radiological invasiveness in early-stage lung adenocarcinoma.

METHODS

A retrospective analysis was conducted on patients with early-stage lung adenocarcinoma from Guangdong Provincial People's Hospital and Shenzhen People's Hospital. Manual delineation of pulmonary nodules along the boundary was performed on cross-sectional images to extract radiomic features. Clinicopathological characteristics and radiomic signatures were identified in both cohorts. CTR and radiomic score for every patient were calculated. The performance of CTR and radiomic models were tested and validated in the respective cohorts.

RESULTS

A total of 818 patients from Guangdong Provincial People's Hospital were included in the primary cohort, while 474 patients from Shenzhen People's Hospital constituted an independent validation cohort. Both CTR and radiomic score were identified as independent factors for predicting pathological invasiveness. CTR in two- and three-dimensional modalities exhibited comparable results with areas under the receiver operating characteristic curves and were demonstrated in the validation cohort (area under the curve: 0.807 vs 0.826, P = 0.059) Furthermore, both CTR in two- and three-dimensional modalities was able to stratify patients with significant relapse-free survival (P < 0.000 vs P < 0.000) and overall survival (P = 0.003 vs P = 0.001). The radiomic models in two- and three-dimensional modalities demonstrated favourable discrimination and calibration in independent cohorts (P = 0.189).

CONCLUSIONS

Three-dimensional measurement provides no additional clinical benefit compared to two-dimensional.
Testosterone is positively associated with coronary artery calcium in a low cardiovascular disease risk population
Authors: Trumble Benjamin C , Negrey Jacob , Koebele Stephanie V , Thompson Randall C , Samuel Wann L , Allam Adel H , Beheim Bret , Linda Sutherland M , Sutherland James D , Eid Rodriguez Daniel , Michalik David E , Rowan Chris J , Lombardi Guido P , Garcia Angela R , Cummings Daniel K , Seabright Edmond , Alami Sarah , Kraft Thomas S , Hooper Paul , Buetow Kenneth , Irimia Andrei , Gatz Margaret , Stieglitz Jonathan , Gurven Michael D , Kaplan Hillard , Thomas Gregory S ,   Tsimane Health and Life History Project Teams
Published: November 2023

Background

In industrialized populations, low male testosterone is associated with higher rates of cardiovascular mortality. However, coronary risk factors like obesity impact both testosterone and cardiovascular outcomes. Here, we assess the role of endogenous testosterone on coronary artery calcium in an active subsistence population with relatively low testosterone levels, low cardiovascular risk and low coronary artery calcium scores.

Methodology

In this cross-sectional community-based study, 719 Tsimane forager-horticulturalists in the Bolivian Amazon aged 40+ years underwent computed tomography (49.8% male, mean age 57.6 years).

Results

Coronary artery calcium levels were low; 84.5% had no coronary artery calcium. Zero-inflated negative binomial models found testosterone was positively associated with coronary artery calcium for the full sample (Incidence Rate Ratio [IRR] = 1.477, 95% Confidence Interval [CI] 1.001–2.170, P = 0.031), and in a male-only subset (IRR = 1.532, 95% CI 0.993–2.360, P = 0.053). Testosterone was also positively associated with clinically relevant coronary atherosclerosis (calcium >100 Agatston units) in the full sample (Odds Ratio [OR] = 1.984, 95% CI 1.202–3.275, P = 0.007) and when limited to male-only sample (OR = 2.032, 95% CI 1.118–4.816, P = 0.024). Individuals with coronary artery calcium >100 had 20% higher levels of testosterone than those with calcium <100 (t = –3.201, P = 0.007).

Conclusions and Implications

Among Tsimane, testosterone is positively associated with coronary artery calcium despite generally low normal testosterone levels, minimal atherosclerosis and rare cardiovascular disease (CVD) events. Associations between low testosterone and CVD events in industrialized populations are likely confounded by obesity and other lifestyle factors.
Changes in weight status during the COVID-19 pandemic: impact of educational level and mental health
Authors: Rosenkilde Siri , Sørensen Thorkild I A , Algren Maria H , Thygesen Lau C
Published: November 2023

Background

The COVID-19 pandemic has resulted in a disruption of daily routines and changes in health behaviors leading to widespread concerns about unfavorable changes in weight status and a potential increase in the prevalence of obesity. This study examined the long-term impact of the COVID-19 pandemic on changes in weight status and its possible dependency on educational level and mental health.

Methods

The study utilizes the Danish Health and Well-being Survey with repeated self-reported information on weight status collected before the COVID-19 pandemic (autumn of 2019) and twice during the pandemic (autumns of 2020 and 2021). Information on educational level was derived from registers, whereas mental health was measured using validated scales. Generalized estimating equations were performed to investigate changes in mean weight and body mass index (BMI) category (BMI < 30 to BMI ≥ 30) between 2019 and 2021 and to investigate potential differences in changes in weight status by pre-pandemic educational level and mental health.

Results

Mean weight significantly increased by 0.34 kg [95% confidence interval (CI): 0.16–0.51] in 2020 and by 0.46 kg (95% CI: 0.26–0.66) in 2021 compared with pre-pandemic weight status. The increase was greater among individuals with lower educational levels and poorer mental health. There were no significant changes in BMI category during the pandemic.

Conclusion

The results showed a significant increase in mean weight among the Danish population, particularly among individuals with lower educational levels and poorer mental health, but without detectable differences in obesity, supporting a long-term but minor impact of the COVID-19 pandemic on weight status.
Adolescent behavioural risk screening in primary care: physician’s point of view
Authors: Eisner-Fellay Taslina , Suris Joan-Carles , Barrense-Dias Yara
Published: November 2023

Background

Despite regular consultation between adolescents/young adults (AYA) and their physicians, they are not regularly screened for psychosocial risk behaviours. This study examines physicians’ self-reported psychosocial risk behaviour screening in AYA. It aims to highlight which elements hinder or improve screening abilities.

Methodology

The design was a cross-sectional quantitative survey. Data were obtained through a self-reported questionnaire sent out to primary care physicians (PCP) in Switzerland in 2018. The target population consisted of 1,824 PCP (29% response rate). Participants were asked whether they screened youths from 3 age groups [10–14 y/o, 15–20 y/o, and 21–25y/o] for the HEEADSSS items during child well visits and routine checkups. Barriers to screening included primary consultation motive prioritization, insufficient time, patient compliance, reimbursement, lack of skills related to adolescent health, lack of referral options. Data were analysed first through a bivariate analysis using Chi-square tests then through a multinomial logistic regression.

Results

The majority of physicians partook in preventive screening for 3–5 psychosocial risk elements. They reported the primary consultation motive as well as a lack of available time as having a high impact on their screening habits. Physician’s experience and having discussed confidentiality were related to an increase in the number of topics addressed. Confidentiality remained a significant variable throughout all analyses.

Conclusion

Barriers such as lack of consultation time and prioritization issues were found by physicians to be critical but did not hinder screening habits. The main element impacting screening habits was assuring confidentiality and the second is self-efficacy.