Dynamic Resonance Research Articles

Detection of Azo Dyes Using Carbon Dots from Olive Mill Wastes

Azo dyes are widely spread in our day life, being heavily used in cosmetics, healthcare products, textile industries, and as artificial food colorants. This intense industrial activity, which inherently includes their own production, inexorably leads to uncontrolled release of dyes into the environment. As emerging pollutants, their detection, particularly in water systems, is a priority. Herein, a fluorescence-based method was employed for the sensitive and selective detection of anionic and neutral azo dyes. Carbon dots (CDs) synthesized from wet pomace (WP), an abundant semi-solid waste of olive mills, were used as probes. An outstanding capability for detection of azo dyes methyl orange (MO) and methyl red (MR) in aqueous solutions was disclosed, which reached a limit of detection (LOD) of 151 ppb for MO. The selectivity of WP-CDs for the anionic azo dye (MO) was established through competitive experiments with other dyes, either anionic (indigo carmine) or cationic (fuchsin, methylene blue, and rhodamine 6G); perchlorate salts of transition metal cations (Cu(II), Co(II), Fe(II), Fe(III), Hg(II), and Pb(II)); and sodium salts of common anions (NO3−, CO32−, Cl−, and SO42−). Evidence has been collected that supports static quenching as the main transduction event underlying the observed quenching of the probe’s fluorescence, combined with a dynamic resonance energy transfer (RET) mechanism at high MO concentrations.

Dynamic contrast-enhanced MRI and Doppler sonography in patients with squamous cell carcinoma of head and neck treated with induction chemotherapy.

In view of the inherent limitations associated with performing dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) in clinical settings, current study was designed to provide a proof of principle that Doppler sonography and DCE-MRI derived perfusion parameters yield similar hemodynamic information from metastatic lymph nodes in squamous cell carcinomas of head and neck (HNSCCs). Strong positive correlations between volume fraction of plasma space in tissues (Vp ) and blood volume (r=0.72, p=0.02) and between Vp and %area perfused (r=0.65, p=0.04) were observed. Additionally, a moderate positive correlation trending towards significance was obtained between volume transfer constant (Ktrans ) and %area perfused (r=0.49, p=0.09).

Method of dynamic resonance tuning in spintronics of nanosystems

A method is advanced allowing for fast regulation of magnetization direction in magnetic nanosystems. The examples of such systems are polarized nanostructures, magnetic nanomolecules, magnetic nanoclusters, magnetic graphene, dipolar and spinor trapped atoms, and quantum dots. The emphasis in the paper is on magnetic nanomolecules and nanoclusters. The method is based on two principal contrivances: First, the magnetic sample is placed inside a coil of a resonant electric circuit creating a feedback field, and second, there is an external magnetic field that can be varied so that to dynamically support the resonance between the Zeeman frequency of the sample and the natural frequency of the circuit during the motion of the sample magnetization. This method can find applications in the production of memory devices and other spintronic appliances.

339 Relationships of Jugular Bulb Parameters Used as Indicators of Cerebral Perfusion and Metabolism With Cerebral Perfusion and Metabolism After Resuscitation from Cardiac Arrest: A Post-hoc Analysis of Experimental Studies Using a Minipig Model

339 Relationships of Jugular Bulb Parameters Used as Indicators of Cerebral Perfusion and Metabolism With Cerebral Perfusion and Metabolism After Resuscitation from Cardiac Arrest: A Post-hoc Analysis of Experimental Studies Using a Minipig Model

Characterization of carbon fiber reinforced conductive mortars filled with recycled ferrochrome slag aggregates

Recently, it is known that carbon fiber, which is a conductive fiber, is used in different mixture designs and developing electrically conductive cementitious materials. However, the evaluation of ferrochrome as a recycled aggregate in the mixture of these special concretes has still not been investigated. In this study, electrically conductive mortars were produced by using 100% recycled ferrochrome aggregate with a particle size of less than 1 mm as filling material and using carbon fiber (CF) in 4 different ratios, 0%, 0.5%, 0.75% and 1%. 2, 14, 28, 90 and 180 days electrical resistivity properties of the obtained samples were investigated. In addition, 28-day compressive strength, flexural strength, dynamic resonance, ultrasonic pulse velocity (UPV), Leeb hardness, scanning electron microscope (SEM) and X-Ray Diffraction (XRD) tests were performed on all samples. The obtained results were compared with the literature and it was proved that ferrochrome can be used as a reasonable aggregate in conductive mortars.

Characterization of carbon fiber reinforced conductive mortars filled with recycled ferrochrome slag aggregates

Recently, it has been known that carbon fiber, a conductive fiber, is used in different mixture designs and the development of electrically conductive cementitious materials. However, the evaluation of ferrochrome slag as a recycled aggregate in the mixture of these special concretes has still not been investigated. In this study, electrically conductive mortars were produced using 100% recycled ferrochrome slag aggregate with a particle size of less than 1 mm as filling material and using carbon fiber in 4 different ratios, 0%, 0.5%, 0.75%, and 1%. To investigate the electrical conductivity properties, the resistivity values of the samples were measured at five different times within 2–180 days. In addition, 28-day compressive strength, flexural strength, dynamic resonance, ultrasonic pulse velocity, Leeb hardness, scanning electron microscope, and X-Ray Diffraction tests were performed on all samples. The results were compared with the literature, proving that ferrochrome slag could be used as a reasonable aggregate in conductive mortars. The age effect was minimal in CF-added mixtures. With the addition of 1% CF, the resistivity values decreased approximately 40 times compared to the reference. Moreover, SEM analyses of the CF-0.75 sample showed that the CFs adhered to form a conductive network between the components in the ferrochrome-filled compact structure.

ZnO nanoparticles and compositional dependence of structural, thermal, mechanical and electrical properties of eutectic SAC355 lead-free solder

Purpose This paper aims to summarise the effects of ZnO nanoparticles (0.1, 0.3, 0.5, 0.7 and 1.0 Wt.%) on the structure, mechanical, electrical and thermal stability of Sn–3.5Ag–0.5Cu (SAC355) solder alloys for high-performance applications. Design/methodology/approach The phase identification and morphology of the solders were studied using X-ray diffraction and scanning electron microscopy. Thermal parameters were investigated using differential scanning calorimetry. The elastic parameters such as Young's modulus (E) and internal friction (Q−1) were investigated using the dynamic resonance technique, whereas the Vickers hardness (Hv) and creep indentation (n) were examined using a Vickers microhardness tester. Findings Microstructural analysis revealed that ZnO nanoparticles (NPs) were distributed uniformly throughout the Sn matrix. Furthermore, addition of 0.1, 0.3 and 0.7 Wt.% of ZnO NPs to the eutectic (SAC355) prevented crystallite size reduction, which increased the strength of the solder alloy. Mechanical parameters such as Young's modulus improved significantly at 0.1, 0.3 and 0.7 Wt.% ZnO NP contents compared to the ZnO-free alloy. This variation can be understood by considering the plastic deformation. The Vickers hardness value (Hv) increased to its maximum as the ZnO NP content increased to 0.5. A stress exponent value (n) of approximately two in most composite solder alloys suggested that grain boundary sliding was the dominant mechanism in this system. The electrical resistance (ρ) increased its maximum value at 0.5 Wt.% ZnO NPs content. The addition of ZnO NPs to plain (SAC355) solder alloys increased the melting temperature (Tm) by a few degrees. Originality/value Development of eutectic (SAC355) lead-free solder doped with ZnO NPs use for electronic packaging.

Dynamic risk resonance between crude oil and stock market by econophysics and machine learning

Changes in crude oil prices have a strong impact on global stock markets. As the largest importer of crude oil, China’s international crude oil market and stock market have a strong risk of contagion. It is of great significance to study the stochastic resonance effect between crude oil market and Chinese stock market. This paper proposes the dynamic risk resonance analysis method based on econophysics and machine learning. From the perspective of stochastic resonance in nonequilibrium statistical physics, we set up a new periodic capital asset pricing model based on econophysics and asset pricing theory, and introduce signal power amplification to describe the risk resonance effect of crude oil price and Chinese stock market. Then, we analyze the dynamic risk resonance between crude oil and stock market impacted by systemic risk and investor heterogeneity. The results demonstrate that: (1) Based on machine learning and predictive testing, the in-sample and out-of-sample forecasting results show that the proposed new periodic model has better fitting performance than the benchmark model; (2) There are optimal system parameters and period information to minimize the risk resonance effect between two markets; (3) The existence of optimal investor heterogeneity leads to inverse resonance behavior between the two markets, which greatly reduces the contagion of market risks.

Quantitative parameters derived from 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging can accurately estimate the histologic grade of hypopharyngeal squamous cell carcinoma preoperatively.

Among head and neck cancers, hypopharyngeal squamous cell carcinoma (HSCC) shows the highest malignancy, which is associated with histologic grading. This study was designed to investigate whether quantitative parameters derived from 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) can preoperatively estimate the histologic grade of HSCC. 18F-FDG PET/MRI of neck was successfully performed in 21 patients with histologically proven HSCC including poorly differentiated group (ten patients) and well-moderately differentiated group (eleven patients). Quantitative parameters derived from FDG-PET, diffusion-weighted imaging (DWI), and dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) were calculated based on volume of interest drawn on the tumor and compared between two groups. The efficacy of quantitative parameters for the estimation of histologic grades of HSCC was evaluated. There were statistically significant differences in mean value of standard uptake value (SUV), apparent diffusion coefficient (ADC), and Ktrans derived from 18F-FDG PET/MRI of HSCC between two groups (p < 0.05). There was no statistically significant difference in other quantitative parameters derived from 18F-FDG PET/MRI of HSCC between two groups. The area under the curve (AUC) of the combination of SUVmean, ADCmean, and Ktrans in the estimation of histologic grade of HSCC was 0.936 with sensitivity of 90.0% and specificity of 81.8%. The combination of SUVmean, ADCmean, and Ktrans derived from 18F-FDG PET/MRI can accurately predict the histologic grade of HSCC preoperatively.

Dynamical response and vibrational resonance of a tri-stable energy harvester interfaced with a standard rectifier circuit.

This paper investigates the dynamical response and vibrational resonance (VR) of a piecewise electromechanically coupled tri-stable energy harvester (TEH), which is driven by dual-frequency harmonic excitations. To achieve a stable DC output, the TEH is interfaced with a standard rectifier circuit. Using the harmonic balance method combined with the separation of fast and slow variables, a steady-state response together with the analytical expressions of displacement and harvested power is derived. The multi-solution feature in the amplitude-frequency response is observed and can improve the harvesting performance of the TEH under a low-frequency environment. There is an optimal time constant ratio and electromechanical coupled coefficient to maximize the harvested DC power. Meanwhile, the VR phenomenon of the TEH is explored through the response amplitude of the low-frequency input signal, which implies that an appropriate combination can induce the occurrence of VR and improve the rectified voltage. Similarly, the nonlinear stiffness coefficients can be adjusted by changing the magnet distance to induce the appearance of VR. The theoretical solutions are well supported by numerical simulation and experimental verification. Specifically, the theoretical analysis and experimental evidence illustrate that the harvested power under the VR effect is much higher than that without VR.

Growth and electrical properties of lead-free ferroelectric single crystal Ba0.77Ca0.23TiO3

Ferroelectric materials have been widely used in fields such as capacitors and transducers. A lead-free ferroelectric single crystal (Ba0.77Ca0.23TiO3) was grown by an improved Czochralski method. The composition of the crystal was verified by quantitative analysis. The basic electrical properties such as ferroelectric and dielectric of the Ba0.77Ca0.23TiO3 crystals along different orientations have been investigated. A complete set of dielectric, piezoelectric and elastic parameters were characterized by the dynamic resonance method. BCT crystal along the <001> orientation has the largest piezoelectric constants. Its d33, d31 and d15 were 204 pC/N, −58.3 pC/N and 156.7 pC/N, respectively, and the coupling coefficients are k33, k31, k15, kt were 71%, 30%, 45%, 50%, respectively. These values are better than barium titanate (BT) crystal. At the same time, BCT crystal also has a higher dielectric constant and lower dielectric loss like barium titanate.

Investigation of thermal and mechanical properties of Sn-Zn and Sn-Zn- Bi near-eutectic solder alloys

In the present work, three near-eutectic lead-free solder melts of Sn-8wt.%Zn; Sn-8wt.%Zn-2wt.%Bi and Sn-8wt.%Zn-4wt.%Bi have swiftly solidified by means of the melt-spinning technique for intermediate –step soldering. The thermal and various mechanical properties of the formed melt-spun ribbons were investigated by dynamic resonance technique, Vickers micro-hardness test under annealing temperatures in the range from 348 K to 448 K. Thermal analysis using differential thermal analysis (DTA) technique revealed a decrease in melting point and solidus point with %Bi. Wettability property was determined by evaluating the contact angle on a different substrate and found to be in the range 31° to 43° on Cu or CuZn30 substrates and in the range from 110° to 115° on Al substrate. The microhardness tests as a function of temperature were performed to determine the stiffness of Sn-Zn solder alloys. Isothermal creep curves for the synthesized samples alloys were determined and plotted under constant applied stresses at a constant temperature of 463 K. Microstructure of the as-cast alloys both, at room temperature and annealed at 348 K were recorded. The creep test on the structure change and properties of Sn–Zn alloys were reported with the effect of the cold work deformation. The Sn-8wt.%Zn-4wt.%Bi is a candidate material for solder which is free of Pb and widely used for packaging of micromechanical systems as a hermetic sealing step.

Effects of Sb and/or Sn concentrations on the SbSn formation in a ternary melt-spun Pb–Sb–Sn alloy

The Pb–Sb–Sn alloy still considered a mandatory choice in the production of the metallic grids in lead-acid batteries. This work aims to study the effects of the commutative concentration of Sb and Sn on the formation of SbSn IMC in ternary melt-spun Pb–Sb–Sn alloy, as well as the effects of initiated on its structural, mechanical and electrical properties. X-ray diffractions (XRD), Dynamic resonance technique, Vickers hardness tester, and High Precision Micro-ohmmeter were used to investigate the melt-spun Pb–Sb–Sn alloys. The results showed that a balanced Sb–Sn content in the melt-spun Pb80–Sb10–Sn10 alloy results in a high concentration of refined SbSn and small particle sizes for α-Pb and SbSn (44.37 and 20.13 nm respectively), low lattice distortion (4.56 × 10−4), low cell volume (120.993 (Å)3), and the highest density (9.232 g/cm3) compared to that of the other melt-spun alloys. Mechanical improvements in terms of room-temperature dynamic Young's modulus (20.8 GPa), bulk modulus (42.3 GPa), shear modulus (7.2 GPa), and Vickers micro-hardness (115.706 MPa) have been revealed, which are strongly related to structural changes. The refined and high concentration of SbSn is responsible for its improved electrical conduction and electrical stability at elevated temperatures (its electrical performance). The aforementioned characteristics suggest that melt-spun alloy is more reliable for use in harsh environments, such as under the hood of a vehicle.

Tunable plasmonics with Au nanoparticles coupled to thin film vanadium dioxide

The development of active devices featuring dynamic tunable plasmonic resonances is vital for wide implementation in many optoelectronic devices. By coupling plasmonic nanoparticles to an underlying thin film of phase change material vanadium dioxide (VO2), dynamic tuning of the plasmon resonance can be achieved within the visible and near IR spectral regions. It is shown through selection of single nanoparticle or dimer structures, the plasmon resonances can be tuned over a large spectral range, the scattering cross-section can be increased, and the E-field enhancement and spatial profile can be controlled via the VO2 phase transition. Hybrid Au nanocuboid–VO­2 structures exhibit larger reversible wavelength shifts than rounded nanoparticles, such as rods and discs, of similar dimensions. A plasmon resonance shift of over 600 nm is observed in the near-IR after the semiconducting to metallic VO2 phase transition. The largest increases in the scattering cross-section are achieved with a VO2 thin film thickness of 30–50 nm. Disc, rod, bowtie and cuboid dimers show larger increases of the scattering cross-section at lower wavelengths, even extending into the visible spectral range. On VO2 phase transition the bowtie dimers can provide an increase in the scattering cross-section of over 70% and 3.6-fold increase in the E-field intensity within the dimer gap. Additionally, the near-field enhancement spreads over the entire height of the dimer gap, and in particular, there is a large enhancement at the surface of the dimers. The increased scattering cross-section and modification of the spatial profile of the E-field enhancement provides mechanisms for tunable metasurfaces.

How to orchestrate a soccer team: Generalized synchronization promoted by rhythmic acoustic stimuli.

Interpersonal coordination requires precise actions concerted in space and time in a self-organized manner. We found, using soccer teams as a testing ground, that a common timeframe provided by adequate acoustic stimuli improves the interplay between teammates. We provide quantitative evidence that the connectivity between teammates and the scoring rate of male soccer teams improve significantly when playing under the influence of an appropriate acoustic environment. Unexpectedly, female teams do not show any improvement under the same experimental conditions. We show by follow-up experiments that the acoustic rhythm modulates the attention level of the participants with a pronounced tempo preference and a marked gender difference in the preferred tempo. These results lead to a consistent explanation in terms of the dynamical system theory, nonlinear resonances, and dynamic attention theory, which may illuminate generic mechanisms of the brain dynamics and may have an impact on the design of novel training strategies in team sports.

Capture in Regime of a Trapped Motion with Further Inelastic Collision for Finite-Sized Asteroid in ER3BP

The application of a modern solving algorithm or method of resolving dynamical equations for small projectile of finite sizes orbiting to be captured in a trapped zigzaging oscillations on orbit around the another large asteroid and in a further inelastic colliding scenario with him (using a formulation of the elliptic restricted three-body problem, ER3BP) is studied semi-analytically. Herein, two primaries MSun and mp (mp &lt; MSun) revolve around their barycenter on Keplerian orbits with low eccentricities. A smaller body (projectile for attacking a large asteroid) is supposed to be a solid, almost symmetric ellipsoid, having the gravitational potential of the MacCullagh type. Our aim is to develop a previously introduced solving procedure and to investigate the updated dynamics of the projectile captured to a trapped dynamical resonance, thereby having the inelastic collision of a small projectile orbiting on quasi-stable elliptic orbits around the large asteroid, mp.

Ultraviolet supercontinuum generation driven by ionic coherence in a strong laser field

Supercontinuum (SC) light sources hold versatile applications in many fields ranging from imaging microscopic structural dynamics to achieving frequency comb metrology. Although such broadband light sources are readily accessible in the visible and near infrared regime, the ultraviolet (UV) extension of SC spectrum is still challenging. Here, we demonstrate that the joint contribution of strong field ionization and quantum resonance leads to the unexpected UV continuum radiation spanning the 100 nm bandwidth in molecular nitrogen ions. Quantum coherences in a bunch of ionic levels are found to be created by dynamic Stark-assisted multiphoton resonances following tunneling ionization. We show that the dynamical evolution of the coherence-enhanced polarization wave gives rise to laser-assisted continuum emission inside the laser field and free-induction decay after the laser field, which jointly contribute to the SC generation together with fifth harmonics. As proof of principle, we also show the application of the SC radiation in the absorption spectroscopy. This work offers an alternative scheme for constructing exotic SC sources, and opens up the territory of ionic quantum optics in the strong-field regime.

Resonance Suppression of a Controllable Mechanism Welding Robot End with Central Composite Design Methodology

Aiming to achieve resonance suppression of a controllable mechanism welding robot end using dynamic modeling and experimental verification, this paper applies a central composite design methodology to optimize suppression resonance using three variables: excitation source, rod stiffness and damping. Considering the coupling effects of the excitation source, member stiffness and damping, a combination optimization is carried out, and the optimal control result of the end is obtained, for which the optimized peak amplitudes are significantly reduced. The research provides an important technical basis for the dynamic design and resonance suppression control of controllable welding robot mechanisms.

ZnO nanoparticles and compositional dependence of structural, thermal, mechanical, and electrical properties for eutectic SAC355 lead-free solder alloys

The purpose of this paper is to investigate the reliability of mechanical, thermal, and electrical properties of the eutectic Sn96Ag3.5Cu0.5 (SAC355) alloys doping with ZnO nanoparticle as a function of doping concentration. SAC355 and (SAC355)100-x(ZnO)x (x = 0.1, 0.3, 0.5, 0.7 and 1 wt%) composite solders were prepared by melt-spinning technique, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and dynamic resonance techniques (DRT) were used to examine their structural, thermal and mechanical properties after the addition of ZnO NPs, respectively. The results show that by adding ZnO NPs to the solder alloy, the grains can be refined to a certain degree, and generate some significant improvements in internal friction (Q−1), microhardness (Hv), yield stress (σ), melting temperature (Tm) and electrical resistivity (ρ) enhancement. Elastic modulus (E) fluctuation may be due to variation in particle size for β-Sn. The Debye temperature (θD) was determined by Lindemann's melting theory from the values of elastic constants. The stress exponent (n) values were in the range 1.83–3.45 which indicates grain boundary sliding and viscous glide mechanisms. According to their favorable physical properties, the addition of ZnO NPs may be useful in many future structural applications.

Impact of manganese sulfide (MnS) oxygenation-induced oxidization on aqueous organic contaminants: Insight into the role of the hydroxyl radical (HO·)

Manganese sulfide (MnS) has unique reactive abilities and can affect the fate and toxicity of contaminants in the natural environment, specifically sulfidic sediments that undergo biogeochemical changes due to natural and artificial processes. However, the effect of oxidization induced by the oxygenation of MnS on organic contaminants remains poorly understood. Herein, we revealed that the hydroxyl radical (HO·) was the dominant reactive oxidant for the rapid degradation of the assessed hydrophobic organic contaminants (including azo dye, nitroaromatic compounds, pesticide, and an endocrine disrupt chemical) during the oxygenation of MnS based on the competitive dynamic experiments, quenching experiments and electron spin resonance (ESR) methods. The removal rates of the assessed organic contaminants were significantly dependent on MnS dosage and co-solutes, including sediment humic acid, metal ions (Mn2+and Fe3+), and inorganic anions (PO43−and Cl−). HO· scavenging by sulfide and its oxidation products (e.g., elemental sulfur), rather than dissolved Mn2+, was responsible for the low utilization efficiency of HO· for the assessed contaminants. The contribution of the manganese oxide (MnO2) generated by the oxygenation of MnS to the examined degradation of contaminants could be neglected. Considered collectively, the reaction between H2O2 and MnO2 generated superoxide radicals (O2−·) which dominated the generation of HO· in an oxic MnS suspension. The results suggest that the impact of oxidization induced by the oxygenation of MnS on environmental contaminants should be of concern in both natural and engineered systems.