Uniform Stability Research Articles

DES/O microemulsion for solubilizing and delivering curcumin via the nasal administration to treat acute asthma

As a natural small molecule drug derived from turmeric, curcumin is known for its good biosafety and a range of beneficial effects, including anti-inflammatory, anti-spasmodic, antioxidant, antibacterial, anti-tumor, and neuroprotective effects. Even though, its insolubility in water and instability severely limit its bioavailability and clinical applications. The present study developed a deep eutectic solvent (DES) in oil microemulsion (DES/O-ME) system loaded with Cur for intranasal administration, aiming to enhance both the solubility and permeability of Cur to significantly increase its bioavailability. The project first constructed and screened the optimal choline chloride-based DES. Subsequently, the DES/O-ME system was prepared and optimized to achieve uniform particle size and stability using a pseudo-ternary phase diagram and electrical conductivity measurements. The resulting DES/O-ME system was thoroughly evaluated for its solubilization efficacy, permeability, mucosal cytotoxicity, and stability. Additionally, the therapeutic efficacy of the Cur-DES/O-ME was assessed in vivo using a murine model of allergic asthma. This comprehensive evaluation highlights the potential of the DES/O-ME system as a promising intranasal drug delivery platform to overcome the limitations of curcumin’s bioavailability and clinical application.

Uniform boundary stabilization of a high-order finite element space discretization of the 1-d wave equation

Uniform boundary stabilization of a high-order finite element space discretization of the 1-d wave equation

Influence of functionalized and non-functionalized 2D graphene nanomaterial with organic phase change materials: Thermal performance comparison

Thermal energy storage and harvesting using phase change materials (PCMs) is a crucial aspect of solar thermal utilisation and energy management. However, the intrinsic limitations associated with PCMs, such as their relatively lower thermal conductivity and sluggish thermal transport pose significant obstacles in the advancement of thermal energy harvesting and storage systems reliant on PCMs. Research explored by inclusion of nanomaterial with the PCM matrix is predominant depending on uniform diffusion and stability of the developed nanocomposite. In this research endeavour, we introduce a novel and synergistic approach to synthesis a functionalized graphene nanomaterials and compare its performance with non-functionalized graphene nanomaterial at various concentrations within organic PCMs, operating at a phase change temperature of 54 °C. The formulated nanocomposite’s thermophysical properties morphology, chemical stability, optical absorbance & transmittance, melting enthalpy, thermal stability and thermal reliability were investigated using sensitive instruments. The findings unveil a remarkable enhancement in thermal conductivity with functionalized graphene dispersed PCM exhibiting an astonishing surge of 106.7 % at a mere 0.8 wt% loading, when contrasted with conventional PCM. The optical transmittance of RT54-0.8fGr was significantly reduced from 56 % to 17.2 %, which enabled the effectiveness for solar thermal energy harnessing; meanwhile the melting enthalpy was energised to 193.4 J/g from 182.6 J/g. The developed nanocomposite with better optical property and melting enthalpy were tested for 500 numbers of accelerated thermal cycles and its chemical stability and thermal property were compared with PCM. Furthermore, a heat transfer analysis is numerically simulated to exhibit the thermal conductance performance of functionalized nanocomposite PCM over base PCM. The findings suggest that the functionalized graphene dispersed PCM matrix to exhibit highly favourable attributes for renewable thermal energy storage due to their exceptional comprehensive features.

Multi-Strategy Bald Eagle Search Algorithm Embedded Orthogonal Learning for Wireless Sensor Network (WSN) Coverage Optimization

Coverage control is a fundamental and critical issue in plentiful wireless sensor network (WSN) applications. Aiming at the high-dimensional optimization problem of sensor node deployment and the complexity of the monitoring area, an orthogonal learning multi-strategy bald eagle search (OLMBES) algorithm is proposed to optimize the location deployment of sensor nodes. This paper incorporates three kinds of strategies into the bald eagle search (BES) algorithm, including Lévy flight, quasi-reflection-based learning, and quadratic interpolation, which enhances the global exploration ability of the algorithm and accelerates the convergence speed. Furthermore, orthogonal learning is integrated into BES to improve the algorithm’s robustness and premature convergence problem. By this way, population search information is fully utilized to generate a more superior position guidance vector, which helps the algorithm jump out of the local optimal solution. Simulation results on CEC2014 benchmark functions reveal that the optimization performance of the proposed approach is better than that of the existing method. On the WSN coverage optimization problem, the proposed method has greater network coverage ratio, node uniformity, and stronger optimization stability when compared to other state-of-the-art algorithms.

Stabilisation of linear waves with inhomogeneous Neumann boundary conditions

ABSTRACT We study linear damped and viscoelastic wave equations evolving on a bounded domain. For both models, we assume that waves are subject to an inhomogeneous Neumann boundary condition on a portion of the domain's boundary. The analysis of these models presents additional interesting features and challenges compared to their homogeneous counterparts. In the present context, energy depends on the boundary trace of velocity. It is not clear in advance how this quantity should be controlled based on the given data, due to regularity issues. However, we establish global existence and also prove uniform stabilisation of solutions with decay rates characterised by the Neumann input. We supplement these results with numerical simulations in which the data do not necessarily satisfy the given assumptions for decay. These simulations provide, at a numerical level, insights into how energy could possibly change in the presence of, for example, improper data.

Improving extensions for the global uniform asymptotic stability of continuous-time nonlinear systems

This paper considers the classical problems of global asymptotic stability (GAS) of nonlinear autonomous (time-invariant) systems and global uniform asymptotic stability (GUAS) of nonlinear non-autonomous (time-varying) systems. By imposing new conditions on the Lyapunov function and its derivative, the state convergence to the origin from any initial condition with bounded norm in the classical setting is extended to the initial conditions with unbounded norms in the present work. The proposed new notions of stability are called extended global asymptotic stability (EGAS) and extended global uniform asymptotic stability (EGUAS) in this paper. The proposed Lyapunov-based criteria yield the global asymptotic stability of the origin and fixed-time/predefined-time attractiveness of any selected neighbourhood of the origin. The result is that the dynamical behaviour of the state trajectories from the convergence time point of view is improved considerably. The relationship between the smoothness and input-to-state stability (ISS) properties is also studied from a quantitative point of view. Under some new sufficient conditions, it is shown that dynamical systems with smaller Lipschitz constants represent smaller ultimate bounds, and as a result, are more robust. The desirable dynamical behaviour and robustness property of the proposed stability notion makes it comparable with the finite/fixed/predefined/prescribed (exact) stable systems that are naturally non-Lipschitz at the origin. Numerical results illustrate the effectiveness of the proposed theoretical results.

Uniform Stabilization for the Semi-linear Wave Equation with Nonlinear Kelvin–Voigt Damping

Uniform Stabilization for the Semi-linear Wave Equation with Nonlinear Kelvin–Voigt Damping

On the Novel Auxiliary Lyapunov Function and Uniform Asymptotic Practical Stability of Nonlinear Impulsive Caputo Fractional Differential Equations via New Modelled Generalized Dini Derivative

In this paper, the uniform asymptotic practical stability of nonlinear impulsive Caputo fractional differential equations with fixed moments of impulse is examined using an auxiliary Lyapunov functions which are analogues of vector Lyapunov functions. Together with comparison results, sufficient conditions for the uniform practical stability as well as the uniform asymptotic practical stability of the impulsive Caputo fractional order systems are established. An illustrative example is given to confirm the suitability of the obtained results.

Functionalized MXene (Ti3C2TX) Loaded with Ag Nanoparticles as a Raman Scattering Substrate for Rapid Furfural Detection in Baijiu.

Furfural is an essential compound that contributes to the distinctive flavor of sauce-flavored Baijiu. However, traditional detection methods are hindered by lengthy and complex sample preparation procedures, as well as the need for expensive equipment. Therefore, there is an urgent need for a new approach that allows rapid detection. In this study, we developed a novel surface-enhanced Raman spectroscopy (SERS) substrate by constructing MXene (Ti3C2TX) @Ag nanoparticles (Ag NPs) through an electrostatic attraction method. The MXene (Ti3C2TX) @Ag NPs were successfully fabricated, with adsorbed NaCl-treated Ag NPs uniformly absorbed on the surface of MXene (Ti3C2TX), creating high-density distributed SERS "hot spots". The prepared substrate demonstrated excellent sensitivity, uniformity, repeatability, and long-term stability, with a low detectable concentration of 10-9 M for R6G (Rhodamine 6G) and an enhancement factor of up to 7.08 × 105. When applied for the in situ SERS detection of furfural in Baijiu, the detection limit was as low as 0.5 mg/L. Overall, the proposed method offers rapid, low-cost, and sensitive quantitative analysis, which is significant not only for detecting furfural in Baijiu but also for identifying hazardous substances and distinguishing between authentic and counterfeit Baijiu products.

Unraveling the Ultrasonic-Assisted Synthesis of Green-Emitting CsPbBr3@Cs4PbBr6: Reaction Process, Luminescence Property, and Display Application.

The pursuit of stable and highly emissive perovskite materials has garnered increasing attention in optoelectronic applications. Green-emitting CsPbBr3@Cs4PbBr6, as a green-emissive material in the solid-state form, has great potential as a color conversion material for full-color displays. However, it is a challenge to achieve mass preparation under ambient conditions. Meanwhile, the formation mechanism is ambiguous. This study reports a ligand-free and rapid mass synthesis of nanomicrosized CsPbBr3@Cs4PbBr6 solid via an ultrasonic-assisted method. The synthesized CsPbBr3@Cs4PbBr6 solids exhibit uniform morphology, high stability, and solid-state quantum efficiency of approximately 55%. Moreover, the transformation mechanism from Pb-Br complexes in the synthesis process is fully investigated by monitoring the phase and spectral evolution. By employing it as a green emitter, the obtained white light-emitting diode (LED) device shows high performance with a correlation color temperature of 7635 K and a wide color gamut of 123% NTSC. This study offers a low-cost and simple operation mass production method for solid-state perovskite powders with excellent chemical stability. Additionally, it provides new insights into the formation mechanism of highly efficient perovskite materials and promotes their practical applications.

Exponential stability for a classical structural acoustic model with thermoelastic boundary control

The uniform stabilization of a coupled system arising in the active control of noise in a cavity with a flexible boundary (strings under thermal effects) is considered. Unlike most articles on this subject, which employ the scalar wave equation when analyzing the asymptotic behavior of structural acoustic models, in this paper, we consider classical equations in terms of flow velocity and pressure to describe the acoustic vibrations of the fluid which fills the cavity. This allows to consider, for example, more realistic boundary conditions to model the coupling on the interface between the acoustic chamber and the wall. The main result of this paper, concerning the exponential stability of the model, is established by means of the frequency domain method and the semigroup theory. This method can be adapted to other first‐order hyperbolic dissipative systems as well.

Towards sharper excess risk bounds for differentially private pairwise learning

Pairwise learning is a vital part of machine learning. It depends on pairs of training instances, and is naturally fit for modeling relationships between samples. However, as a data driven paradigm, it faces huge privacy issues. Differential privacy (DP) is a useful tool to protect the privacy of machine learning, but corresponding excess population risk bounds are loose in existing DP pairwise learning analysis. In this paper, we propose a gradient perturbation algorithm for pairwise learning to get better risk bounds under Polyak–Łojasiewicz condition, including both convex and non-convex cases. Specifically, for the theoretical risk bound in expectation, previous best results are of rates O(pn2ϵ2+1n) and O(pnϵ+1n) under strongly convex condition and convex conditions, respectively. In this paper, we use the on-average stability and achieve an O(min{pn1.5ϵ+p1.5n2.5ϵ3,pn2ϵ2+1n}) bound, significantly improving previous bounds. For the high probability risk bound, previous best results are analyzed by the uniform stability, and O(βnU+pnϵ) excess population risk bounds are achieved under strongly convex or convex conditions, where βnU is the traditional pairwise uniform stability parameter, it is large since it considers the worst case of the loss sensitivity. In this paper, we propose the pairwise locally elastic stability and improve the high probability bound to O(βEn+pnϵ), in which the pairwise locally elastic stability parameter βE≪βnU because it considers the average sensitivity of the pairwise loss function.

Uniform exponential stability approximations of semi‐discretization schemes for two hybrid systems

The uniform exponential stabilities (UESs) of two hybrid control systems comprised of a wave equation and a second‐order ordinary differential equation are investigated in this study. Linear feedback law and local viscosity are considered, as are nonlinear feedback law and internal anti‐damping. The hybrid system is first reduced to a first‐order port‐Hamiltonian system with dynamical boundary conditions, and the resulting system is discretized using the average central‐difference scheme. Second, the UES of the discrete system is obtained without prior knowledge of the exponential stability of the continuous system. The frequency domain characterization of UES for a family of contractive semigroups and the discrete multiplier approach are used to validate the main conclusions. Finally, the Trotter–Kato theorem is used to perform a convergence study on the numerical approximation approach. Most notably, the exponential stability of the continuous system is derived by the convergence of energy and UES, which is a novel approach to studying the exponential stability of some complex systems. Numerical simulation is used to validate the effectiveness of the numerical approximating strategy.

Impact of mixed boundary conditions and nonsmooth data on layer‐originated nonpremixed combustion problems: Higher‐order convergence analysis

AbstractThis work explores the theoretical and computational impacts of mixed‐type flux conditions and nonsmooth data on boundary/interior layer‐originated singularly perturbed semilinear reaction–diffusion problems. Such problems are prevalent in nonpremixed combustion models and catalytic reaction models. The inclusion of arbitrarily small diffusion terms results in boundary layers influenced by specific flux conditions normalized by perturbation parameters. We have demonstrated theoretically that the sharpness of the boundary layer is significantly reduced when this normalization is independent of the diffusion parameter. In addition, the presence of a nonsmooth source function gives rise to an interior layer in the current problem. We show that using upwind discretizations for mixed boundary fluxes achieves nearly second‐order accuracy if the first derivatives are not normalized concerning perturbation parameters. This outcome arises from the bounds of a prior derivative of the continuous solution. Furthermore, it is theoretically shown that nearly second‐order uniform accuracy can be attained for reaction‐dominated semilinear problems using a hybrid scheme at the discontinuity point. To ensure the uniform stability of the discrete solution, a transformation is necessary for the corresponding discrete problem. Theoretical results are supported by various experiments on nonlinear problems, illustrating the pointwise rates and highlighting both linear and higher‐order accuracy at specific points.

Improved encapsulation efficiency and storage stability of lutein by soy protein isolate nanocarriers with thermal and trypsin treatments.

Encapsulation of bioactive compounds within protein-based nanoparticles has garnered considerable attention in the food and pharmaceutical industries because of its potential to enhance stability and delivery. Soy protein isolate (SPI) has emerged as a promising candidate, prompting the present study aiming to modify its properties through controlled thermal and trypsin treatments for improved encapsulation efficiency (EE) of lutein and its storage stability. The EE of lutein nanoparticles encapsulated using SPI trypsin hydrolysates (SPIT) with three varying degrees of hydrolysis (4.11%, 6.91% and 10.61% for SPIT1, SPIT2 and SPIT3, respectively) increased by 12.00%, 15.78% and 18.59%, respectively, compared to SPI. Additionally, the photostability of SPIT2 showed a remarkable increase of 38.21% compared to SPI. The superior encapsulation efficiency and photostability of SPIT2 was attributed to increased exposure of hydrophobic groups, excellent antioxidant activity and uniform particle stability, despite exhibiting lower binding affinity to lutein compared to SPI. Furthermore, in SPIT2, the protein structure unfolded, with minimal impact on overall secondary structure upon lutein addition. The precise application of controlled thermal and trypsin treatments to SPI has been shown to effectively produce protein nanoparticles with substantially improved encapsulation efficiency for lutein and enhanced storage stability of the encapsulated lutein. These findings underscore the potential of controlled thermal and trypsin treatments to modify protein properties effectively and offer significant opportunities for expanding the applications of protein-based formulations across diverse fields. © 2024 Society of Chemical Industry.

Magnetic-responsive sensors based on polydopamine macromolecules for highly sensitive detection of trace food colorant residues

As a kind of unique biomimetic macromolecule, polydopamine (PDA) have prominent in-situ reduction ability and interfacial adhesion. In this work, combined with in-situ reduction ability of PDA and excellent magnetic response performance of nickel foam (NF), a strategy was designed to fabricate a series of NF@PDA@AgNPs as magnetic-responsive surface enhancement Raman scattering (SERS) substrates for highly sensitive Rhodamine B (RhB) detection in chili powder. With crystal violet (CV) as probe molecule, the detection limit of SERS substrate could achieve 10−10 M, and the enhancement factor was as high as to 2.22 × 107. In addition, the NF@PDA@AgNPs SERS substrates showed excellent magnetic separation efficiency, good SERS uniformity and storage stability. More importantly, these substrates could achieve highly efficient collection and sensitive detection of RhB residues in chili powder by magnetic adsorption method, and the detection of limit was as low as to be 10−6 g/g. These NF@PDA@AgNPs substrates would be a great prospect for rapid and efficient pernicious contaminant detection in the chemical and biological fields.

Uniform Practical Asymptotic Stability for Position Control of Underwater Snake Robots

Uniform Practical Asymptotic Stability for Position Control of Underwater Snake Robots

Equivalent conditions for the synchronization of identical linear systems over arbitrary interconnections

We propose necessary and sufficient conditions for the synchronization of N identical single-input–single-output (SISO) systems, connected through a directed graph without imposing any assumption on the graph interconnection. We consider both the continuous-time and the discrete-time case, and we provide conditions that are equivalent to the uniform global exponential stability, with guaranteed convergence rate, of the closed and unbounded attractor that corresponds to the synchronization set.

Poly(vinyl chloride) Films Incorporated with Antioxidant ZnO-Flavonoid Nanoparticles: A Strategy for Food Preservation.

Antioxidant films were prepared using poly(vinyl chloride) (PVC) incorporated with 0.5% or 1.0% zinc oxide (ZnO)-flavonoid (quercetin or morin) nanoparticles (NPZnO-Q% or NPZnO-M%) via the casting method. NP incorporation within the polymer matrix influenced the structural, morphological, optical, and thermal properties of the PVC-based films, as well as their antioxidant activity as assessed using the DPPH radical scavenging method. Our results indicated that increasing ZnO-flavonoid NP concentration increased films thickness, while reducing ultraviolet light (UV) transmittance but conserving transparency. The presence of NPZnO-Q% or NPZnO-M% improved the surface uniformity and thermal stability of the active films. In terms of antioxidant activity, there was an enhancement in the DPPH radical scavenging capacity (PVC/ZnO-Q1.0% > PVC/ZnO-Q0.5% > PVC/ZnO-M0.5% > PVC/ZnO-M1.0% > PVC), suggesting that the packaging can help protect food from oxidative processes. Therefore, these antioxidant films represent an innovative strategy for using as active food packaging material, especially intended for aiding in quality preservation and extending the shelf life of fatty foods.

Polynomial Decay of the Energy of Solutions of the Timoshenko System with Two Boundary Fractional Dissipations

In this study, we examine Timoshenko systems with boundary conditions featuring two types of fractional dissipations. By applying semigroup theory, we demonstrate the existence and uniqueness of solutions. Our analysis shows that while the system exhibits strong stability, it does not achieve uniform stability. Consequently, we derive a polynomial decay rate for the system.