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Highlights: MXene film absorbers enable the near theoretical absorption strength in extremely wide wavebands of 0.5–10 THz. Achieving high absorption in broad terahertz bands has long been challenging for terahertz electromagnetic wave absorbers. Recently in Nature Photonics, Xiao et al. reported the high absorption approaching the theoretical upper limit across the whole terahertz band of MXene-based terahertz absorbers and, on this basis, constructed an applicable, updated alternating current impedance matching model. [ABSTRACT FROM AUTHOR]

The presents the model of the evolution of coating and substrate composition with a given initial distribution under conditions of short-term thermal exposure. In the model takes into account both crossing phenomena (thermodiffusion and diffusive thermal conductivity) and finiteness of velocities of heat and mass fluxes. The role of the crossing effects and chemical reactions is shown. Stresses and strains are estimated from the known temperature and concentration distributions. The value of stresses depends on the initial coating and substrate composition, relaxation times, parameters of chemical reactions and cross effects. [ABSTRACT FROM AUTHOR]

For the first time, numerical solutions were computed using fractional-order strain considerations in the current study. For an isotropic and homogeneous nanobeam, the thermoelasticity with one relaxation time and fractional-order strain theory based on Caputo–Fabrizio's definition of fractional derivative was examined. With thermal loading and in simply supported boundary conditions, the Laplace transformations have been used upon the governing equations and its inversion was computed using the Tzou technique approximation. The numerical calculations for a thermoelastic rectangular gold (Au) nanobeam have been validated as a model where ramp-type heat is considered. The computational solutions have been depicted in two-dimensions graphs for several situations to investigate the impact of the fractional-order and ramping heat parameters on all of the functions studied. The temperature increment distribution, lateral vibration, deformation, tension, and energy density are all influenced by fractional-order and ramp-time heat parameters. The ramp-time heat parameter might be utilized to regulate nanobeam vibration and energy damping in thermoelastic nanobeams. [ABSTRACT FROM AUTHOR]

Acute respiratory distress syndrome (ARDS) is a life-threatening condition characterized by the rapid onset of lung inflammation Therefore, monitoring the spatial distribution of the drug directly administered to heterogeneously damaged lungs is desirable. In this work, we focus on optimizing the drug N-acetylcysteine (NAC) adsorption on poly-l-lysine-modified magnetic nanoparticles (PLLMNPs) to monitor the drug spatial distribution in the lungs using magnetic resonance imaging (MRI) techniques. The physicochemical characterizations of the samples were conducted in terms of morphology, particle size distributions, surface charge, and magnetic properties followed by the thermogravimetric quantification of NAC coating and cytotoxicity experiments. The sample with the theoretical NAC loading concentration of 0.25 mg/mL was selected as an optimum due to the hydrodynamic nanoparticle size of 154 nm, the surface charge of +32 mV, good stability, and no cytotoxicity. Finally, MRI relaxometry confirmed the suitability of the sample to study the spatial distribution of the drug in vivo using MRI protocols. We showed the prevailing transverse relaxation with high transverse relaxivity values and a high r2(*)/r1 ratio, causing visible hypointensity in the final MRI signal. Furthermore, NAC adsorption significantly affects the relaxation properties of PLLMNPs, which can help monitor drug release in vitro/in vivo. [ABSTRACT FROM AUTHOR]

Background: Magnetic nanoparticles (MNPs) are used as tracers without ionizing radiation in vascular imaging, molecular imaging, and neuroimaging. The relaxation mechanisms of magnetization in response to excitation magnetic fields are important features of MNPs. The basic relaxation mechanisms include internal rotation (Néel relaxation) and external physical rotation (Brownian relaxation). Accurate measurement of these relaxation times may provide high sensitivity for predicting MNP types and viscosity‐based hydrodynamic states. It is challenging to separately measure the Néel and Brownian relaxation components using sinusoidal excitation in conventional MPI. Purpose: We developed a multi‐exponential relaxation spectral analysis method to separately measure the Néel and Brownian relaxation times in the magnetization recovery process in pulsed vascular MPI. Methods: Synomag‐D samples with different viscosities were excited using pulsed excitation in a trapezoidal‐waveform relaxometer. The samples were excited at different field amplitudes ranging from 0.5 to 10 mT at intervals of 0.5 mT. The inverse Laplace transform‐based spectral analysis of the relaxation‐induced decay signal in the field‐flat phase was performed by using PDCO, a primal‐dual interior method for convex objectives. Néel and Brownian relaxation peaks were elucidated and measured on samples with various glycerol and gelatin concentrations. The sensitivity of viscosity prediction of the decoupled relaxation times was evaluated. A digital vascular phantom was designed to mimic a plaque with viscous MNPs and a catheter with immobilized MNPs. Spectral imaging of the digital vascular phantom was simulated by combining a field‐free point with homogeneous pulsed excitation. The relationship between the Brownian relaxation time from different tissues and the number of periods for signal averages was evaluated for a scan time estimation in the simulation. Results: The relaxation spectra of synomag‐D samples with different viscosity levels exhibited two relaxation time peaks. The Brownian relaxation time had a positive linear relationship with the viscosity in the range 0.9 to 3.2 mPa · s. When the viscosity was >3.2 mPa · s, the Brownian relaxation time saturated and did not change with increasing viscosity. The Néel relaxation time decreased slightly with an increase in the viscosity. The Néel relaxation time exhibited a similar saturation effect when the viscosity level was >3.2 mPa · s for all field amplitudes. The sensitivity of the Brownian relaxation time increased with the field amplitude and was maximized at approximately 4.5 mT. The plaque and catheter regions were differentiated from the vessel region in the simulated Brownian relaxation time map. The simulation results show that the Néel relaxation time was 8.33±0.09 μs in the plaque region, 8.30±0.08 μs in the catheter region, and 8.46±0.11 μs in the vessel region. The Brownian relaxation time was 36.60±2.31 μs in the plaque region, 30.17±1.24 μs in the catheter region, and 31.21±1.53 μs in the vessel region. If we used 20 excitation periods for image acquisition in the simulation, the total scan time of the digital phantom was approximately 100 s. Conclusion: Quantitative assessment of the Néel and Brownian relaxation times through inverse Laplace transform‐based spectral analysis in pulsed excitation, highlighting their potential for use in multi‐contrast vascular MPI. [ABSTRACT FROM AUTHOR]

We are devoted to the physical analysis of the habitat area of warm-blooded organisms - humans and many mammals. For this purpose, the establishment of equilibrium distribution of carbon dioxide in aqueous solutions of salts in contact with atmospheric air starting from some time is investigated. More precisely, the relaxation time of carbon dioxide, as a function of temperature and pH, is investigated. It is found that the pH-relaxation time tS is a very nontrivial function of temperature, pH values, and NaCl salt concentration. It was assumed that the minimum value of pH relaxation time corresponds to the optimal rate of physical processes in living matter. Using this selection principle and our experimental data, we have shown that the optimal temperature for human and mammalian life activity is close to To = 37 °C. The lower and upper temperature limits for their possible activity are close to Tl = 30 °C and Tu = 42 °C, respectively. The optimal value of pHo, determined by the same selection principle, also becomes true if supplemented by the influence of albumin and other proteins. [ABSTRACT FROM AUTHOR]

L-arginine capped and transition metal-doped Ultra-Small Iron Oxide Nanoparticles (USIONs) were synthesized by a wet chemical method. The nanoparticles (NPs) were encapsulated with Pluronic F127® and used as a vehicle (M2+/Fe3O4@L-Arg/P) to load anti-cancer drug. The interaction of ligand molecules with NPs surface was studied by FTIR spectroscopy, while the Vibrating Sample Magnetometry and Mössbauer spectroscopy were used for magnetic properties. In vitro, drug release kinetics showed that Mn2+/Fe3O4@L-Arg/P/bg release 30% drug initially within 5 h and the next 20% in 72 h with an overall 50% release in three days. Approximately, 70% drug was released from Ni2+/Fe3O4@L-Arg/P/bg. The Mn2+/Fe3O4@L-Arg/P/bg took a long time to 70% release rate than Zn2+ and Ni2+-doped vehicles. M2+/Fe3O4@L-Arg/P/bg with 10 μg/mL dosage can reduce the cell viability to 53, 31, and 94 for Zn2+, Mn2+, and Ni2+, respectively. Contrasting ability of the material was evaluated for Magnetic Resonance Imaging (MRI). The results indicate a shift from inherent T2 to T1 contrasting with a lower concentration. The parameters (like τM,τR,q, etc.) used in Solomon–Bloembergen–Morgan (SBM) theory for paramagnetic relaxation also be applicable to Fe3O4-based NPs system in terms of H-bonding to modulate the T1 contrasting in MRI. Ultra-Small Iron Oxide Nanoparticles are designed for theranostic applications. Both the core and the shell environment of the nanoparticle assembly can be modulated to achieve optimum performance in terms of drug delivery and contrasting effect under magnetic field. [ABSTRACT FROM AUTHOR]

We investigate the external field effect on opinion formation based on the majority rule and q -voter models on a complete graph. The external field can be considered as the mass media in the social system, with the probability p agents following the mass media opinion. Based on our Monte Carlo simulation, the mass media effect is not strong enough to make the system reach a homogeneous state (complete consensus) with the magnetization m = 1 for all values of p , indicating the existence of a usual phase transition for all values of p. In the q -voter model, the mass media eliminates the usual phase transition at p ≈ 0. 2 1. We obtain the model's critical point and scaling parameters using the finite-size scaling analysis and obtain that both models have the same scaling parameters. The external field effect decreases both models' relaxation time and the relaxation time following the power-law relation such as τ ∼ N β , where N is the population size and β depends on the probability p. In the majority rule model, β follows a linear relation, and in the q-voter model, β follows a power-law relation. [ABSTRACT FROM AUTHOR]

It is well-known that poly(2-methoxyethyl acrylate) (PMEA) exhibits excellent blood compatibility and various investigations have examined the underlying mechanism of this compatibility in terms of the water structure in PMEA and/or inherent PMEA properties. However, information regarding the dynamic properties of the PMEA remains limited. This study was performed to clarify the effect of water molecules on the structure and dynamic properties of hydrated PMEA by comparing dry PMEA using temperature-variable 13C nuclear magnetic resonance spectroscopy (13C-NMR) with a solution probe at 15 –45 °C. Hydration changed the chemical shift values of the four carbons in the PMEA side chain (−COOCH2CH2OCH3). Investigations of spin-lattice relaxation times and resonance peak widths showed that hydration increased PMEA mobility and the side chain mobility markedly changed at approximately 30 °C, especially in dry PMEA. [ABSTRACT FROM AUTHOR]

In this research work, we have prepared lithium lead silicate glasses with varying concentrations of bismuth by following the melt-quench technique. The prepared samples are investigated by ac conductivity and electric modulus formalisms in the frequency and temperature ranges of 10–1–107 Hz and 433–533 K, respectively. To check the applicability of various charge transport mechanisms in these prepared samples, the experimental data of ac conductivity was fitted with Jonscher's power law. It was found to be satisfied in the studied range of temperature and frequency. AC conductivity helps to calculate all the parameters viz.; dc conductivity, activation energy, frequency exponent parameter, and the cross over frequency. The value of ac conductivity increases with Bi2O3 concentration up to 30 mol% due to mobile lithium ions and the network modifier BiO6 unit. Thereafter, when the ratio of Bi2O3/Li2O becomes greater than unity, the conductivity values decrease due to the blocking effect of the bismuth ions in the network, forming the BiO3 pyramidal unit. In the current research, the correlated barrier hopping model is found to be suitable for explaining the ac conduction mechanism. [ABSTRACT FROM AUTHOR]

Raw complex permittivity data of pure aromatic hydrocarbons such as Xylene, O-Xylene (O-X), M-Xylene (M-X), and P-Xylene (P-X) have been measured for different temperatures in 10 MHz to 50 GHz frequency range using Time Domain Dielectric Spectroscopy (TDDS). Dielectric relaxation for above systems has been characterized by the Debye type spectral relaxation. The dielectric parameters such as static dielectric constant, relaxation time, Kirkwood correlation factor have been determined using the non-linear least square fit method. Effect of O-, M-, and P- substitution of CH3 group in xylene causes variation in static dielectric constant values and spectacle deviation in relaxation time with respect to temperature. The temperature dependent dielectric relaxation gives expected Arrhenius behavior. [ABSTRACT FROM AUTHOR]

Based on the time–temperature equivalence principle, the relationship between the melt relaxation time (MRT) and melt heating temperature (MHT) in an improved gas‐assisted extrusion (GAE) of a polypropylene (PP) sheet was investigated by numerical simulations. In the simulations, the MRT was varied and the inherent properties of the MHT were controlled using experimental methods. With an increase in MRT, the velocity in all directions, pressure drop, and shear rate of the melt increased; however, increasing the MRT does not always yield a positive effect on the GAE process of the melt. For instance, the melt velocity increased vertically at the die exit with MRT, resulting in an outward extrudate swell. In addition, the extruded product was intact when the melt was heated to 220°C, which verified the principle of time–temperature equivalence. [ABSTRACT FROM AUTHOR]

In this study, the dielectric parameters of E7 coded nematic liquid crystal (NLC) composites containing the different amounts of rubrene fluorescent dye were investigated. E7, E7+0.5 wt.% Rubrene, and E7+1.0 wt.% Rubrene samples were prepared. Frequency dependent dielectric constants (ε' and ε"), dielectric anisotropy (Δe'), and ac conductivity (sac) graphs of rubrene doped E7 NLC composites were obtained by dielectric spectroscopy method and compared with pure E7 NLC. By using these graphs, relaxation frequency (fR), relaxation time (tR), dielectric strength (σ'), and crossover frequency (fc) parameters of the E7 NLC and its rubrene doped composites were determined. An increase in fR from 3.045 MHz to 3.697 MHz for 0 V and from 627 kHz to 686 kHz for 40 V was observed with increasing rubrene concentration. On the other hand, a decrease in tR from 0.052 µs to 0.043 µs for 0 V and from 0.254 µs to 0.232 µs for 40 V was seen with increasing rubrene concentration. Furthermore, an increase in fc from 1.145 MHz to 1.298 MHz was obtained with increasing rubrene concentration. The results show that the dielectric parameters change with the concentration of rubrene and it is thought that this study will provide a basis for investigating the dielectric properties of rubrene doped NLC composites. Moreover, it is concluded that the produced composites are a suitable base material for electro-optical device applications such as smart displays, photonics and electrical circuit elements. [ABSTRACT FROM AUTHOR]

A colloidal solution of magnetic nanoparticles (MNPs) modified with biocompatible positively charged poly-L-lysine (PLL) with an oleate (OL) layer employed as an initial coating was produced as a potential MRI contrast agent. The effect of various PLL/MNPs' mass ratios on the samples' hydrodynamic diameter, zeta potential, and isoelectric point (IEP) was studied by the dynamic light-scattering method. The optimal mass ratio for MNPs' surface coating was 0.5 (sample PLL0.5-OL-MNPs). The average hydrodynamic particle size in the sample of PLL0.5-OL-MNPs was 124.4 ± 1.4 nm, and in the PLL-unmodified nanoparticles, it was 60.9 ± 0.2 nm, indicating that the OL-MNPs' surface became covered by PLL. Next, the typical characteristics of the superparamagnetic behavior were observed in all samples. In addition, the decrease in saturation magnetizations from 66.9 Am2/kg for MNPs to 35.9 and 31.6 Am2/kg for sample OL-MNPs and PLL0.5-OL-MNPs also confirmed successful PLL adsorption. Moreover, we show that both OL-MNPs and PLL0.5-OL-MNPs exhibit excellent MRI relaxivity properties and a very high r2(*)/r1 ratio, which is very desirable in biomedical applications with required MRI contrast enhancement. The PLL coating itself appears to be the crucial factor in enhancing the relaxivity of MNPs in MRI relaxometry. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southeast University (English Edition) is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a design process for miniaturized atomic vapor cells using the micro-glassblowing process. It discusses multiple design considerations, including cell geometry, optical properties, materials, and surface coating. The geometry and the optical properties were studied using experimentally verified analytical and Finite Element Models (FEM). The cell construction material and surface coating were the focus of our experimental study on factors that affect the relaxation time (T2) of nuclear spins. We showed that the wafer-level coating process with Al2O3 increased the 131Xe T2 by 3× and by switching from Borosilicate glass (Pyrex) to Aluminosilicate glass (ASG), T2 was improved by 2.5× , for the same species. The improvement in the T2 is projected to reduce the ARW of an NMR gyro and the sensitivity of an NMR magnetometer by 3× with Al2O3 coated cells and by 2.5× with ASG cells. [2019-0158].

The model of internal friction at the migrating intercrystalline boundary is considered. Under the action of an alternating external stress oriented normally to the boundary, compression and stretching of the mating crystallites occurs. Due to their anisotropy and mutual reversal, Young’s modules in the direction of the stress action are different. The volume density of elastic energy in crystallites is different. This leads to the emergence of an effective driving force for boundary migration. As a model, a square segment of the boundary is selected, fixed along the perimeter by triple grain joints. The Laplace stress from the side of the curved boundary is counteracting. The differential equation of the connection of the boundary displacement with the total voltage is solved by the Fourier method. Based on this solution, the internal friction is calculated. The relaxation time spectrum consists of a series of lines. Each of them corresponds to the peak of Debye. The main peak has a significant value, smaller peaks are superimposed on it. The resulting maximum of internal friction widens in comparison with the Debye peak.

This paper proposes a hyperbolic heat transport model for a homogeneously perfused biological tissue irradiated by a laser beam. In particular, involving two local energy equations, one for the blood vessel and the other for the tissue, a non-Fourier-like heat equation is introduced and solved analytically using the Laplace transform method. The generalized hyperbolic model obtained is reduced to Pennes' heat transport equation in case the thermal delay time is zero and the solution obtained is in accordance with the numerical and experimental data existing in the literature. In addition, the achieved results also show that the effects of thermal relaxation and blood perfusion on temperature distribution are similar; indeed the highest temperature is expected when the delay time tR increases during tissue cooling. Finally, the consequences of the change in the values of the physical parameters characterizing the model are described and the effect of thermal relaxation on the temperature profile in the tissue during and after laser application is investigated.

Time Domain Reflectometry (TDR) and frequency domain techniques have been used for the dielectric measurement of methyl cellulose (MC) with water for different concentrations and frequency ranges from 20 Hz to 2 MHz and 10 MHz to 30 GHz at 25°C. The dielectric relaxation in these mixtures can be represented by the Debye relaxation behaviour. The dielectric parameters such as complex permittivity ε*(ω), complex electrical modulus M*(ω), complex electrical conductivity σ*(ω), loss tangent (tan δ), static dielectric constant (ε0) and relaxation time (τ) have been determined. The variation of dielectric parameters of methyl cellulose (MC) in water suggested that methyl cellulose (MC) bonds with water alter its structure and electric dipole moment. [ABSTRACT FROM AUTHOR]

The results of temperature measurements in the lower thermosphere at altitudes of 90–130 km by the method of resonant scattering of radio waves on artificial periodic inhomogeneities (APIs) of the ionospheric plasma are presented. These inhomogeneities are created when the ionosphere is exposed to powerful HF radio emission. The temperature profile was obtained from measurements of the relaxation time of the API scattered signal. The data processes and the method of the temperature determination are given in detail. The height and temporal resolutions of the API technique are of the order of 1 km and 15 s, respectively, making it possible to study both fast and slow processes in the lower thermosphere. Large temperature variability at altitudes of 90–130 km during the day and from day to day, due to the propagation of atmospheric waves, has been confirmed. The temporal variations of the atmospheric parameters take place with periods from 15 min to some hours. There are often height profiles of the temperature with the wave-like variations and with the vertical scale of about 4–10 km. The irregular temperature profiles were observed above 100 km. [ABSTRACT FROM AUTHOR]

The electronic and thermoelectric properties of a CaSbK half-Heusler compound are investigated by combining ab initio calculations and Boltzmann transport theory. Taking into account the total energy as a function of the volume, the type I structure is found to be the most stable among the considered phases. The lattice stability of the compound is borne out by the results of mechanical, dynamical and thermodynamic properties. The electronic band structure calculations reveal an indirect bandgap (L–Γ) with high valence band degeneracy, leading to high DOS effective mass of holes. To assess the lattice thermal conductivity, both the Slack model and ShengBTE code are used. Electron and hole relaxation times are also computed using the deformation potential theory. The transport parameters are examined with respect to the carrier concentration at 300 K, 500 K and 700 K for n- and p-type doping. At 700 K, n-doped CaSbK exhibits a high figure of merit value of 1.54 with optimized carrier concentration of 2.8 × 1019 cm−3. Consequently, the CaSbK compound stands out as a promising candidate for thermoelectric applications. [ABSTRACT FROM AUTHOR]

Theoretical predictions of dust-explosion characteristics, such as the minimum explosive concentration (MEC), can help improve the accuracy of quantitative risk assessment. This paper presents a continuum model to simulate one-dimensional dust-cloud combustion. It is found that the dilution of dust by thermal expansion reduces the propagation speed of a combustion wave through a dust cloud. At the same time, the delay in the increase of particle velocity due to relaxation time counteracts the dilution effect. Therefore, neglecting the relaxation time results in the underestimation of propagation speed. In the absence of heat loss, extinction occurs when the adiabatic combustion temperature decreases to the ignition temperature; MEC is independent of particle size in such cases. With the presence of heat loss, on the other hand, extinction occurs at a higher dust concentration; MEC increases with particle size. Accurate evaluation of ignition temperature is key to the quantitative prediction of MEC. A particular focus is given to gravity effects, reflecting recent experimental efforts to obtain fundamental insights into propagation mechanisms without being affected by gravity. In upward propagation, particles fall toward the reaction front, enhancing combustion and increasing the propagation speed. The situation in downward propagation is the opposite, and extinction occurs when the gravity level is beyond a critical value. In upward propagation, MEC can decrease with an increase in particle size, owing to the influence of gravity. [ABSTRACT FROM AUTHOR]

The gelation time t g necessary for a solution of functional (associating) molecules to reach its gel point after a temperature jump, or a sudden concentration change, is theoretically calculated on the basis of the kinetic equation for the stepwise cross-linking reaction as a function of the concentration, temperature, functionality f of the molecules, and multiplicity k of the cross-link junctions. It is shown that quite generally t g can be decomposed into the product of the relaxation time t R and a thermodynamic factor Q. They are functions of a single scaled concentration x ≡ λ (T) ϕ , where λ (T) is the association constant and ϕ is the concentration. Therefore, the superposition principle holds with λ (T) as a shift factor of the concentration. Additionally, they all depend on the rate constants of the cross-link reaction, and hence it is possible to estimate these microscopic parameters from macroscopic measurements of t g . The thermodynamic factor Q is shown to depend on the quench depth. It generates a singularity of logarithmic divergence as the temperature (concentration) approaches the equilibrium gel point, while the relaxation time t R changes continuously across it. Gelation time t g obeys a power law t g − 1 ∼ x n in the high concentration region, whose power index n is related to the multiplicity of the cross-links. The retardation effect on the gelation time due to the reversibility of the cross-linking is explicitly calculated for some specific models of cross-linking to find the rate-controlling steps in order for the minimization of the gelation time to be easier in the gel processing. For a micellar cross-linking covering a wide range of the multiplicity, as seen in hydrophobically-modified water-soluble polymers, t R is shown to obey a formula similar to the Aniansson–Wall law. [ABSTRACT FROM AUTHOR]

Graphical abstract A calibrated palpation sensor has been developed for making instrumented Digital Rectal Examinations (iDREs) with a view to assessing patients for prostate cancer. The instrument measures the dynamic stiffness of the palpable surface of the prostate, and has been trialled on 12 patients in vivo. The patients had been diagnosed with prostate cancer and were scheduled for radical prostatectomy. As far as possible, patients with asymmetric disease were chosen so as to give a variation in gland condition over the palpable surface. The device works by applying an oscillating pressure (force) to a flexible probe whose displacement into the tissue is also measured in order to yield a dynamic stiffness, the static stiffness being incidentally measured at the mean oscillatory force. The device was deployed mounted on the index finger of a urologist and measurements taken at 12–16 positions on each patient using light and firm pressure and palpation frequencies of 1 or 5 Hz. In parallel, conventional DRE assessments were made by a consultant urologist for cancer. After in vivo measurement, the glands were removed and examined histologically with each palpation point being classified as cancerous (C) or not (NC). The work has established the first measurements of static modulus of living prostate tissue to be: 26.8 (13.3) kPa for tissue affected by prostate cancer (C classification), and 24.8 kPa (11.9) for tissue unaffected by cancer (NC classification), values quoted as median (interquartile range). The dynamic properties were characterised by: dynamic modulus, 5.15 kPa (4.86) for the C classification and 4.61 kPa (3.08) for the NC classification and the time lag between force and displacement at 5 Hz palpation frequency, 0.0175 s (0.0078) for the C classification and 0.0186 s (0.0397) for the NC classification, values again quoted as median (interquartile range). With the limited set of features that could be generated, an Artificial Neural Network (ANN) classification yielded a sensitivity of 97%, negative predictive value of 86%, positive predictive value of 67% and accuracy of 70% but with relatively poor specificity (30%). Besides extending the feature set, there are a number of changes in probe design, probing strategy and in mechanics analysis, which are expected to improve the diagnostic capabilities of the method. [ABSTRACT FROM AUTHOR]

Single‐molecule magnets (SMMs) show wide potential applications in the field of ultrahigh‐density storage materials, quantum computing, spintronics, and so on. Lanthanide (Ln) SMMs, as an important category of SMMs, open up a promising prospect due to their large magnetic moments and huge magnetic anisotropy. However, the construction of high performance for Ln SMMs remains an enormous challenge. Although remarkable advances are focused on the topic of Ln SMMs, the research on Ln SMMs with different nuclear numbers is still deficient. Therefore, this review summarizes the design strategies for the construction of Ln SMMs, as well as the metal skeleton types. Furthermore, we collect reported Ln SMMs with mononuclearity, dinuclearity, and multinuclearity (three or more Ln spin centers) and the SMM properties including energy barrier (Ueff) and pre‐exponential factor (τ0) are described. Finally, Ln SMMs with low‐nuclearity SMMs, especially for single‐ion magnets (SIMs), are highlighted to understand the correlations between structures and magnetic behavior of the detail SMM properties are described. We expect the review can shed light on the future developments of high‐performance Ln SMMs. [ABSTRACT FROM AUTHOR]

Degeneration of cartilage can be studied non-invasively with quantitative MRI. A promising parameter for detecting early osteoarthritis in articular cartilage is T 1 ρ , which can be tuned via the amplitude of the spin-lock pulse. By measuring T 1 ρ at several spin-lock amplitudes, the dispersion of T 1 ρ is obtained. The aim of this study is to find out if the dispersion contains diagnostically relevant information complementary to a T 1 ρ measurement at a single spin-lock amplitude. To this end, five differently acquired dispersion parameters are utilized; A , B , τ c , T 1 ρ /T 2 , and R 2 − R 1 ρ. An open dataset of an equine model of post-traumatic cartilage was utilized to assess the T 1 ρ dispersion parameters for the evaluation of cartilage degeneration. Firstly, the parameters were compared for their sensitivity in detecting degenerative changes. Secondly, the relationship of the dispersion parameters to histological and biomechanical reference parameters was studied. Parameters A , T 1 ρ /T 2 , and R 2 − R 1 ρ were found to be sensitive to lesion-induced changes in the cartilage within sample. Strong correlations of several dispersion parameters with optical density, as well as with collagen fibril angle were found. Most of the dispersion parameters correlated strongly with individual T 1 ρ values. The results suggest that dispersion parameters can in some cases provide a more accurate description of the biochemical composition of cartilage as compared to conventional MRI parameters. However, in most cases the information given by the dispersion parameters is more of a refinement than complementary to conventional quantitative MRI. [ABSTRACT FROM AUTHOR]

In this work, the heterojunction ZnTe/ZnMnTe/GaAs has been fabricated using the molecular beam epitaxially (MBE) technique. The electric complex impedance has been used to characterize the as-prepared junction at different illumination powers in a wide range of frequencies. It was found that the impedance of the studied junction has the highest value at the darkest point and then decreases with the increase in the applied frequency, illumination power, or both of them. The Cole–Cole diagram showed two relaxation processes for the studied junction for illumination power larger than 10 mWcm−2. Only one relaxation process has been observed for illumination powers greater than 10 mWcm−2. The dielectric relaxation time showed an increase with the increase of the illumination power. Accordingly, the prepared heterojunction can be suggested for use as a photo-sensor and/or photo-switch applications. [ABSTRACT FROM AUTHOR]

Featured Application: Computation of Relaxation Time Maps in Magnetic Resonance Imaging. Magnetic resonance imaging (MRI) is a valuable diagnostic tool that provides detailed information about the structure and function of tissues in the human body. In particular, measuring relaxation times, such as T1 and T2, can provide important insights into the composition and properties of different tissues. Accurate relaxation time mapping is therefore critical for clinical diagnosis and treatment planning, as it can help to identify and characterize pathological conditions, monitor disease progression, and guide interventions. However, the computation of relaxation time maps in MRI is a complex and challenging task that requires sophisticated mathematical algorithms. Thus, there is a need for robust and accurate algorithms that can reliably extract the desired information from MRI data. This article compares the performance of the Reduced Dimension Nonlinear Least Squares (RD-NLS) algorithm versus several widely used algorithms to compute relaxation times in MRI, such as Levenberg-Marquardt and Nelder-Mead. RD-NLS simplifies the search space for the optimum fit by leveraging the partial linear relationship between signal intensity and model parameters. The comparison was performed on several datasets and signal models, resulting in T1 and T2 maps. The algorithms were evaluated based on their fit error, with the RD-NLS algorithm showing a lower error than other fit-ting algorithms. The improvement was particularly notable in T1 maps, with less of a difference in T2 maps. Additionally, the average T1 values computed with different algorithms differed by up to 14 ms, indicating the importance of algorithm selection. These results suggest that the RD-NLS algorithm outperforms other commonly used algorithms for computing relaxation times in MRI. [ABSTRACT FROM AUTHOR]

Copyright of Special Oil & Gas Reservoirs is the property of Special Oil & Gas Reservoirs Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper demonstrates existence of deviatoric stress waves in thermoviscoelastic (TVE) solid continua due to rheology in addition to the presence of usual deviatoric stress waves purely due to elasticity of the solid continua. The physical mechanisms that enable existence of deviatoric stress waves due to rheology in TVE solid continua are identified. Evolutions of deviatoric stress waves due to rheology are presented. Propagation, reflection, transmission, and interaction of such waves in conjunction with usual elastic stress waves are presented. The parameters controlling the rheological deviatoric stress waves and the speed of propagation of composite deviatoric stress waves due to rheology and elasticity are identified, discussed and illustrated through model problem studies. Mathematical model for the TVE solids in R 1 is constructed using conservation and balance laws of classical continuum mechanics in R 3 and the constitutive theories that are derived using entropy inequality and representation theorem. Model problems and their solutions are also presented to illustrate the validity of the concepts presented in the paper. [ABSTRACT FROM AUTHOR]

Objectives: To quantitatively measure the T1 value, T2 value, proton density (PD) value, and cerebral blood flow (CBF) in young and middle-aged primary insomnia (PI) patients, and analyze the correlations between relaxation times, PD, and CBF to explore potential brain changes. Methods: Cranial magnetic resonance (MR) images of 44 PI patients and 30 healthy subjects were prospectively collected for analysis. The T1, T2, PD, and CBF values of the frontal lobe, parietal lobe, temporal lobe, and occipital lobe were independently measured using three-dimensional arterial spin labeling (3D-ASL), synthetic magnetic resonance imaging (syMRI) and a whole-brain automatic segmentation method. The differences of these imaging indices were compared between PI patients and healthy subjects. Follow-up MR images were obtained from PI patients after 6 months to compare with pre-treatment images. The Wilcoxon signed rank test and Spearman rank were used for statistical analysis. Results: Bilateral CBF asymmetry was observed in 38 patients, with significant differences in both the T2 value and CBF between the four lobes of the brain (p < 0.01). However, no significant difference was found in the T1 and PD values between the bilateral lobes. A negative correlation was found between CBF and T2 values in the right four lobes of patients with primary insomnia (PI). During follow-up examinations, five PI patients showed a disappearance of insomnia symptoms and a decrease in CBF in both brain lobes. Conclusion: Insomnia symptoms may be associated with high CBF, and most PI patients have higher CBF and lower T2 values in the right cerebral hemispheres. The right hemisphere appears to play a critical role in the pathophysiology of PI. The 3D-ASL and syMRI technologies can provide a quantitative imaging basis for investigating the brain conditions and changes in young and middle-aged PI patients. [ABSTRACT FROM AUTHOR]

The rheological behavior of the complex hydrogel systems used for water shutoff in high water-cut wells, before and after filtration in cracks with different openings, was studied. The research objects were multicomponent mixtures of solutions of sodium silicate and polyacrylamide (PAA), crosslinked with Cr3+ salts, with additions of solid particles of lignin nature. The experimental data were analyzed using the approach considering the active medium as consisting of many particles, structural elements, each exhibiting a specific relaxation time. It was assumed that the external field of mechanical forces, characterized by shear stress, causes reversible activation excitation and decay of a group of the structural elements. The viscous flow activation energy, determined in the time interval Δt, corresponds to the average energy required to overcome intermolecular forces of various nature. Processing of the data on the rheological characteristics of the hydrogels at different temperatures revealed a quasi-discrete character of the spectra of the structural elements. Analysis of the autocorrelation functions (ACFs) of the spectra indicates a strong cooperative interaction of the structural elements. [ABSTRACT FROM AUTHOR]

The analysis of thermoelastic wave propagation in continuum solids at micro/nano-seconds is especially significant for ultra-fast heating technologies, where strain relaxation effects will increase significantly. In most cases, it is commonly accompanied by a relatively small strain-rate; however, this is questionable in the environment of transient thermal wave propagation under the ultra-fast heating case. The present work is dedicated to constitutive modeling of a novel generalized thermoelasticity model by introducing an additional strain-rate term associated with a relaxation time parameter in the Lord-Shulman (LS) thermoelasticity with the aid of an extended thermodynamics framework. As an application, the newly developed model is applied to a one-dimensional half-space problem which is traction free at one end; a time-dependent thermal shock is imposed at the same end to analyze transient responses of thermodynamic field variables (temperature, displacement, strain, and stress). The inclusion of strain-rate in the LS model eliminates the probable propagating jump discontinuities of the strain and stress fields at the wavefront. The current work is expected to be useful in the mathematical modeling and numerical simulation of thermoelastic processes under an ultra-fast heating environment. [ABSTRACT FROM AUTHOR]

Layered transition metal dichalcogenides (TMDs) provide a favorable research platform for the advancement of spintronics and valleytronics because of their unique spin-valley coupling effect, which is attributed to the absence of inversion symmetry coupled with the presence of time-reversal symmetry. To maneuver the valley pseudospin efficiently is of great importance for the fabrication of conceptual devices in microelectronics. Here, we propose a straightforward way to modulate valley pseudospin with interface engineering. An underlying negative correlation between the quantum yield of photoluminescence and the degree of valley polarization was discovered. Enhanced luminous intensities were observed in the MoS2/hBN heterostructure but with a low value of valley polarization, which was in stark contrast to those observed in the MoS2/SiO2 heterostructure. Based on the steady-state and time-resolved optical measurements, we reveal the correlation between exciton lifetime, luminous efficiency, and valley polarization. Our results emphasize the significance of interface engineering for tailoring valley pseudospin in two-dimensional systems and probably advance the progression of the conceptual devices based on TMDs in spintronics and valleytronics. [ABSTRACT FROM AUTHOR]

The complex permittivity spectra of 1, 4-butanediol -1, 4-dioxane binary mixtures have been measured in the frequency range from 10MHz to 30GHz using the time domain reflectometry (TDR) technique. The complex permittivity spectra show the Cole-Davidson type relaxation. The static dielectric constant and relaxation time at various temperatures have been obtained from complex permittivity spectra by using the nonlinear least squares fit method. The orientation of electric dipoles and solute-solvent interaction in the liquid mixture was confirmed from the excess, Bruggeman, Kirkwood correlation factor and thermodynamic parameters. [ABSTRACT FROM AUTHOR]

This paper presents a new method for analysing creeping discharges based on information theory as it applies to medical imaging. The analysis of information surface data is used to determine the impact of relaxation time on the characteristic parameters of creeping discharges. The same information is used to make a comparative study of the morphology of discharges propagating in palm kernel oil methyl ester (PKOME) and in mineral oil (MO). Other comparative methods based on fractal analysis and normality hypothesis tests associated with Anderson Darling (AD), Kolmogorov-Smirnoff (KS) and Shapiro-Wilk (SW) statistics are used. The results show that very short relaxation times increase the error on the measurement of the fractal dimension and the maximum extension of the discharges. A growth of the mutual information between 0 and 60% is observed for relaxation times varying between 60s and 420s respectively. For the same time interval, the P-value increases from 0.027 to 0.821 according to the AD statistic, from 0.01 to more than 0.150 according to KS and from 0.083 to more than 0.1 according to SW. This result indicates that the data are from a normal distribution. After 420s of relaxation, the error on the maximum extension measurement is reduced by 94% in PKOME and 92% in MO. Similarly, the error on the mean fractal dimension in MO is reduced by 86.7% for a relaxation time between 301s and 420s, and by 84.6% in PKOME for a time between 180s and 420s. These different results imply that the impact of the discharge can be predicted when it is in its initial phase during which the number of discharge occurrences is reduced. On the other hand, the physicochemical characteristics of the insulating liquid used dictate the relaxation time to be allowed for the laboratory measurements.

Hyperbolic heat transfer equation considering a laser heat source is analytically investigated using Laplace transform method to study the temperature distribution in the central part of the tibia bone tissue. The target zone is the compact layer of tibia, and the laser irradiation in four near-surface points during 2 s is taken into account. Holmium–Yttrium–Aluminum-Garnet (Ho-YAG) laser is utilized in the simulations. Results indicate that there is a trilateral relationship among the temperature changes of various points in the tissue, the power used and the wavelength. While neglecting the effects of blood circulation upon laser interaction with the bone surface, the results reveal that the temperature of the points adjacent to the bone surface dramatically increases up to 85 °C. Meanwhile, the heat source is provided based on the Beer-Lambert law, and finally it demonstrates that the penetration depth exponentially reduces the intensity and causing considerable decrease in temperature. For the first time, the non-Fourier heat transfer equation was solved using the Laplace transform method for the tibia bone, and its results were compared with the numerical solution results using the Leap- Frog method. Knowing the temperature changes caused by laser inside the tissue is very crucial in Laser tissue welding, tissue ablation, photocoagulation and photo-thermal denaturation, angioplasty, treatment of granulation tissues, change and deformation of cartilage.

We search for mass segregation in the intermediate-aged open cluster NGC 6819 within a carefully identified sample of probable cluster members. Using photometry from Gaia, Pan-STARRS, and the Two Micron All Sky Survey as inputs for a Bayesian statistics software suite, BASE-9, we identify a rich population of (photometric) binaries and derive posterior distributions for the cluster age, distance, metallicity, and reddening, as well as star-by-star photometric membership probabilities, masses, and mass ratios (for binaries). Within our entire sample, we identify 2632 cluster members and 777 binaries. We then select a main-sequence “primary sample” with 14.85 < G < 19.5, containing 1342 cluster members and 250 binaries with mass ratios q > 0.5, to investigate mass segregation. Within this primary sample, we find the binary radial distribution is significantly shifted toward the cluster center as compared to the single stars, resulting in a binary fraction that increases significantly toward the cluster core. Furthermore, we find that within the binary sample, more massive binaries have more centrally concentrated radial distributions than less massive binaries. The same is true for the single stars. We verify the expectation of mass segregation for this stellar sample in NGC 6819 through both relaxation time arguments and by investigating a sophisticated N -body model of the cluster. Importantly, this is the first study to investigate mass segregation of the binaries in the open cluster NGC 6819.

We present a robust methodology for identifying photometric binaries in star clusters. Using Gaia DR3, Pan-STARRS, and Two Micron All Sky Survey data, we self-consistently define the cluster parameters and binary demographics for the open clusters (OCs) NGC 2168 (M35), NGC 7789, NGC 6819, NGC 2682 (M67), NGC 188, and NGC 6791. These clusters span in age from ∼200 Myr (NGC 2168) to more than ∼8 Gyr (NGC 6791) and have all been extensively studied in the literature. We use the Bayesian Analysis of Stellar Evolution software suite to derive the age, distance, reddening, metallicity, binary fraction, and binary mass-ratio posterior distributions for each cluster. We perform a careful analysis of our completeness and also compare our results to previous spectroscopic surveys. For our sample of main-sequence stars with masses between 0.6 and 1 M _⊙ , we find that these OCs have similar binary fractions that are also broadly consistent with the field multiplicity fraction. Within the clusters, the binary fraction increases dramatically toward the cluster centers, likely a result of mass segregation. Furthermore nearly all clusters show evidence of mass segregation within the single and binary populations. The OC binary fraction increases significantly with cluster age in our sample, possibly due to a combination of mass-segregation and cluster-dissolution processes. We also find a hint of an anticorrelation between binary fraction and cluster central density as well as total cluster mass, possibly due to an increasing frequency of higher-energy close stellar encounters that inhibit long-period binary survival and/or formation.

The simulation of seismic wavefields holds paramount significance in understanding subsurface structures and seismic events. The lattice Boltzmann method (LBM) provides a computational framework adept at capturing detailed wave interactions, offering a new approach to improve seismic wavefield simulations. Our study involves a novel comparative analysis of wavefields using different lattice Boltzmann models, focusing on how relaxation times, discrete velocity models, and collision operators affect simulation accuracy and efficiency. We explore the impacts of distinct relaxation times and evaluate their effects on wave propagation speed and fidelity. By incorporating four discrete velocity models of LBM, we innovatively investigate the trade-off between spatial resolution and computational complexity. Additionally, we delve into the implications of employing three collision operators—single relaxation time (SRT), two relaxation times (TRT), and multiple relaxation times (MRT). By comparing their accuracy and stability, we provide insights into selecting the most suitable collision operator for capturing complex wave interactions. Our research provides a comprehensive framework to optimize the LBM parameters, enhancing both accuracy and efficiency in seismic wave simulations, and offers valuable insights to benefit wave simulation across diverse disciplines.

We present a basic principle and good practices of the rheology of polymers, particularly for teachers or lecturers at colleges or universities for educational purposes, as well as for beginner researchers who may refer to this article as their self-learning resources. Basic consideration of the experimental methods using parallel-plate oscillatory rheometer and step-by-step guidelines for the estimation of the power law dependence of storage, G′ and loss, G″ modulus as well as the estimation of the relaxation time at f cross G′−G′′ ${f}_{\,\mathrm{cross}}^{\,{G}^{\prime }-{G}^{\prime \prime }}$ at terminal zone using various approaches such as commercial graphical software, manual graphical approach and commercial rheometer software are highlighted. Good practices for data interpretation using different approaches are described and compared where the outcomes revealed the manual graphical approach or commercial graphical software yield comparable results with the commercial rheometer software. In order to have better insight, several examples and exercises which are applicable for teaching and self-learning activities are also provided.

Polyacrylonitrile (PAN)-based carbon fibers were chemically modified with a different ratio of Sulfuric acid (SA) to Nitric acid (NA), then reinforced Polyurethane (PU) composites in the presence of carbon fibers were prepared. The structural and surface characteristics of the modified carbon fibers were investigated by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The FTIR results showed the presence of the carbonyl groups in a higher ratio of NA and the formation of carboxyl groups in a lower ratio of NA. The interaction between carbon fiber and PU matrix was studied by the dynamic mechanical thermal analysis (DMTA) method. The DMTA results showed with increasing carbon fiber/PU matrix interaction, the intensity of glass transition temperature decreased. Matching the DMTA results with the power-law model and Cole-Cole diagram showed that the process of carbon fiber modification can increase the amount of chain with a long relaxation time in the PU matrix.

This article discusses the problems of studying the issue of joint motion of liquids in the porous space. The article provides the construction of a mathematical model of the theory of ltration, which describes phase transitions. The main diculty in constructing this model is associated with the fact that free interphase boundaries create regions that change over time, and it is required to nd the temperature or concentration elds of substances in them. In this case, the coordinates of the considered phase boundaries are not initially specied and must be calculated already in the process of solving. For this, a derivation of the averaged equation for the problem of nding the rupture surface during the movement of two incompressible viscous liquids in the pores of the soil skeleton was proposed. The article deals with the case when the skeleton is an absolutely rigid body. The rationale was given for the choice of an averaged ltration model instead of a microscopic one. The main research methods are classical methods of mathematical physics, functional analysis and computation methods of the theory of partial dierential equations, as well as dierence methods. The formulation of the problem is given, and the denition of a generalized solution for solving the problem is provided. Next, an averaged model is derived and the existence of at least one generalized solution to the problem is proved.

One of the main causes of road pavement distress are low temperatures, and hence the need to thoroughly study the low temperature performance of all bituminous materials used in road construction. The purpose of this studywas to determine the performance of alternative and conventional bituminous mixtures in the temperature range between –25˚C and –10˚C using for this purpose the Tensile Creep Test (TCT). The low-temperature performance data were evaluated using the Burgers model, a tool that is widely used for evaluation of bituminous mixtures. This research focuses on bridge paving mixtures. These included both conventional (mastic asphalt) and alternative (SMAMA) materials. It was established, based on the test results and their analysis, that low temperature performance of a bituminous mixture is influenced, in the first place, by the characteristics of the asphalt binder it contains. Furthermore, SMA-MA mixtures showed better low temperature performance than conventional, mastic asphalt type mixtures.

Nanotechnology, which is regarded as one of the major fields of global research, is currently generating more interest. We have worked in this direction for this aim. PP/α-Al2O3 composite samples were exposed to various levels of radiation in the article. The kinetics of changes are shown to be non-linearly dependent on the strength and quantity of the dose according to the findings of research carried out by other researchers. As a result of the effect of gamma radiation, various α-, α'-, β-, δ-, etc. the change of molecular mobility of relaxation and structural elements. For the present period, it is very important to analyze the kinetics of the suggested processes of nanoscale fillers and the electret characteristics of polymer/nanocomposite systems following γ-irradiation. Considering the present importance of electret characteristics in practical applications for polymer/nanocomposite systems. The paper also discusses the lgρv = (T)dependences for PP/α-Al2O3 composite samples exposed to various levels of radiation. The dependences showed that the most thermally stable samples are those that have not been exposed to radiation. The temperature dependency of ρv became more acute when the radiation dose was increased to D = 80 kQr. As a result, load carriers in samples with PP/α-Al2O3 compositions are now more expensive. [ABSTRACT FROM AUTHOR]

In this paper, we theoretically studied the electrical resistivity of the heavily Pr-doped YBa2Cu3O7−δ single crystal high-Tc superconductor cuprate. The proposed formulation expands the concept of relaxation times from frequency (energy) line widths for multiple scattering processes by leveraging electron quantum dynamics with the aid of the double-time electron Green function. A thorough analysis was carried out to investigate the effect of dopant-atom scattering as well as magnon scattering on the temperature and reduced frequency dependences of electrical resistivity in the temperature range of 20–300 K. An acceptable level of agreement between theory and experiment has been achieved. [ABSTRACT FROM AUTHOR]