•Chaotic oscillation of bubbles in liquids is theoretically analyzed.•Dual-frequency approach is proved to be effective for chaos control.•Two routes to chaos in dual-frequency approach are ...identified.•Influential parameters on chaos control are shown.
Chaotic oscillation of bubbles in liquids reduces the efficiency of the sonochemical system and should be suppressed in the practical applications. In the present paper, a chaos control method based on the dual-frequency approach is numerically investigated and is proved to be an effective method even for cases with intensive energy input. It was found that the chaos could be successfully suppressed by the application of dual-frequency approach in a wide range of parameter zone (even with high acoustic pressure amplitude). Furthermore, influences of power allocation between two waves on the chaos control are quantitatively discussed with clear descriptions of the routes from stable oscillations to chaos.
•We investigated the bubble dynamics under the multi-frequency acoustic excitation.•We validated our numerical studies using experimental data.•Combination resonance and simultaneous resonance are ...fully studied.•Influences of paramount parameters on nonlinear bubble oscillations are demonstrated.
The multi-frequency acoustic excitation has been employed to enhance the effects of oscillating bubbles in sonochemistry for many years. In the present paper, nonlinear dynamic oscillations of bubble under dual-frequency acoustic excitation are numerically investigated within a broad range of parameters. By investigating the power spectra and the response curves of oscillating bubbles, two unique features of bubble oscillations under dual-frequency excitation (termed as “combination resonance” and “simultaneous resonance”) are revealed and discussed. Specifically, the amplitudes of the combination resonances are quantitatively compared with those of other traditional resonances (e.g. main resonances, harmonics). The influences of several paramount parameters (e.g., the bubble radius, the acoustic pressure amplitude, the energy allocation between two component waves) on nonlinear bubble oscillations are demonstrated.
In this letter, rectified mass diffusion of gas bubbles in liquids under acoustic field with dual frequencies is theoretically investigated. Comparing with gas bubbles under single-frequency acoustic ...field, if the acoustic pressure amplitude is above a certain value determined in the present work, a wider range of bubbles can grow through rectified mass diffusion with more rapid growth rate under dual-frequency acoustic field.
•Bubble-particle interactions are experimentally investigated using high-speed camera.•Cavitation bubble dynamics and particle moving dynamics are analyzed qualitatively and quantitatively.•Particle ...motion direction depends on stand-off distance between bubble and particle.•Underlying physical mechanisms are given based on the radiation pressure calculation.
The interactions between a laser-generated cavitation bubble and a spherical particle are investigated experimentally with the aid of high-speed camera. Both the cavitation bubble dynamics and its induced particle moving dynamics are clearly recorded and analyzed qualitatively and quantitatively. Influences of two essential parameters (including the bubble-particle distance and the particle/bubble radius ratio) on the phenomenon are given and discussed. Furthermore, the underlying physical mechanisms are discussed based on the calculations of the radiation pressure and the generations of the micro-jet. Our results reveal that the distance between the cavitation bubble and the particle shows significant influences on the phenomenon. For different radius ratios, the maximum particle displacement varies especially for the small stand-off distance.
Heat transfer across interfaces of oscillating gas bubbles in liquids is a fundamental issue of bubble dynamics with many applications. The current formulas in the literature relating with heat ...transfer are either too complex to be used for calculation or not valid for some regions of interest. In this communication, a group of formulas is proposed to predict heat transfer across bubble interfaces accurately for a wide range of parameters. An exact solution is used to validate the accuracy of the present formulas. Finally, energy dissipation during gas bubble oscillations in liquids through heat transfer is quantitatively compared with those through viscosity and acoustic radiation.
•We review human studies on childhood maltreatment and DNA methylation.•The 72 studies identified were mainly retrospective and candidate-gene focussed.•While studies generally support a ...relationship, evidence to date is inconsistent.•Limitations include a lack of longitudinal data, low replication and confounding.•We provide 12 concrete recommendations for moving the field forward.
DNA methylation (DNAm) – an epigenetic process that regulates gene expression – may represent a mechanism for the biological embedding of early traumatic experiences, including childhood maltreatment. Here, we conducted the first systematic review of human studies linking childhood maltreatment to DNAm. In total, 72 studies were included in the review (2008–2018). The majority of extant studies (i) were based on retrospective data in adults, (ii) employed a candidate gene approach (iii) focused on global maltreatment, (iv) were based on easily accessible peripheral tissues, typically blood; and (v) were cross-sectional. Two-thirds of studies (n = 48) also examined maltreatment-related outcomes, such as stress reactivity and psychiatric symptoms. While findings generally support an association between childhood maltreatment and altered patterns of DNAm, factors such as the lack of longitudinal data, low comparability across studies as well as potential genetic and ‘pre-exposure’ environmental confounding currently limit the conclusions that can be drawn. Key challenges are discussed and concrete recommendations for future research are provided to move the field forward.
With superior optical properties, high flexibility in engineering its material properties, and strong capability for large‐scale on‐chip integration, graphene oxide (GO) is an attractive solution for ...on‐chip integration of 2D materials to implement functional integrated photonic devices capable of new features. Over the past decade, integrated GO photonics, representing an innovative merging of integrated photonic devices and thin GO films, has experienced significant development, leading to a surge in many applications covering almost every field of optical sciences such as photovoltaics, optical imaging, sensing, nonlinear optics, and light emitting. This paper reviews the recent advances in this emerging field, providing an overview of the optical properties of GO as well as methods for the on‐chip integration of GO. The main achievements made in GO hybrid integrated photonic devices for diverse applications are summarized. The open challenges as well as the potential for future improvement are also discussed.
The advances in the field of integrated graphene oxide (GO) photonics are reviewed. First, an overview of GO's optical properties, as well as methods for its on‐chip integration, are provided. Next, the main achievements made in GO hybrid integrated photonic devices for diverse applications are summarized. Finally, the open challenges as well as the potential for future improvement are discussed.
In the present paper, an analytical solution of rectified diffusion of processes of gas bubbles in molten metal is derived for the purpose of predicting the diffusion behaviors of gas bubbles during ...ultrasonic degassing. In the present model, a theoretical threshold (in terms of the amplitude of the applied ultrasonic field) is determined for the evaluation of the ultrasonic degassing effects. The diffusion of hydrogen bubbles in molten aluminum is predicted, so as to provide examples to illustrate the important findings of the present work.
•Particle’s effect on bubble and surrounding liquid is analytically analyzed based on Weiss theorem.•Applicability range of the theory is the dimensionless distance greater than 0.50.•Particle effect ...on liquid velocity between bubble and particle is mainly showed as image bubble.•Theoretical prediction model of bubble movement velocity is established based on Kelvin impulse.
In the present paper, the laser-induced cavitation bubble dynamics near a fixed spherical particle is comprehensively investigated based on the Weiss theorem, the Kelvin impulse theory and the high-speed photography experiment. Firstly, the applicability range of the theoretical model in the time and the space is statistically obtained based on sufficient experimental results. Then, the in-depth theoretical analysis is carried out in terms of the liquid flow field and the bubble Kelvin impulse with the corresponding experimental results as the reasonable support. In addition, the theoretical prediction model of the bubble movement is established and experimentally fitted from the analytic expression of the Kelvin impulse. Through our research, it is found that: (1) the applicability range of the Kelvin impulse theory for the bubble near the spherical particle is approximately the dimensionless distance between the bubble and particle (γ) greater than 0.50. (2) The effect of the particle on the liquid velocity between the bubble and the particle is mainly manifested in the form of the image bubble, which always causes the liquid velocity in this region to be significantly lower than other surrounding regions. (3) The average movement velocity of the bubble centroid can be reasonably predicted by establishing a directly proportional function between the Kelvin impulse and the velocity with the relationship constant (α) equal to 3.57×10−6 ± 1.63×10−7 kg.
Aqueous zinc-ion batteries, in terms of integration with high safety, environmental benignity, and low cost, have attracted much attention for powering electronic devices and storage systems. ...However, the interface instability issues at the Zn anode caused by detrimental side reactions such as dendrite growth, hydrogen evolution, and metal corrosion at the solid (anode)/liquid (electrolyte) interface impede their practical applications in the fields requiring long-term performance persistence. Despite the rapid progress in suppressing the side reactions at the materials interface, the mechanism of ion storage and dendrite formation in practical aqueous zinc-ion batteries with dual-cation aqueous electrolytes is still unclear. Herein, we design an interface material consisting of forest-like three-dimensional zinc-copper alloy with engineered surfaces to explore the Zn plating/stripping mode in dual-cation electrolytes. The three-dimensional nanostructured surface of zinc-copper alloy is demonstrated to be in favor of effectively regulating the reaction kinetics of Zn plating/stripping processes. The developed interface materials suppress the dendrite growth on the anode surface towards high-performance persistent aqueous zinc-ion batteries in the aqueous electrolytes containing single and dual cations. This work remarkably enhances the fundamental understanding of dual-cation intercalation chemistry in aqueous electrochemical systems and provides a guide for exploring high-performance aqueous zinc-ion batteries and beyond.
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