Janus Nanofibrous Patch with In Situ Grown Superlubricated Skin for Soft Tissue Repair with Inhibited Postoperative Adhesion.

The patch with a superlubricated surface shows great potential for the prevention of postoperative adhesion during soft tissue repair. However, the existing patches suffer from the destruction of topography during superlubrication coating and lack of pro-healing capability. Herein, we demonstrate a facile and versatile strategy to develop a Janus nanofibrous patch (J-NFP) with antiadhesion and reactive oxygen species (ROS) scavenging functions. Specifically, sequential electrospinning is performed with initiators and CeO2 nanoparticles (CeNPs) embedded on the different sides, followed by subsurface-initiated atom transfer radical polymerization for grafting zwitterionic polymer brushes, introducing superlubricated skin on the surface of single nanofibers. The poly(sulfobetaine methacrylate) brush-grafted patch retains fibrous topography and shows a coefficient of friction of around 0.12, which is reduced by 77% compared with the pristine fibrous patch. Additionally, a significant reduction in protein, platelet, bacteria, and cell adhesion is observed. More importantly, the CeNPs-embedded patch enables ROS scavenging as well as inhibits pro-inflammatory cytokine secretion and promotes anti-inflammatory cytokine levels. Furthermore, the J-NFP can inhibit tissue adhesion and promote repair of both rat skin wounds and intrauterine injuries. The present strategy for developing the Janus patch exhibits enormous prospects for facilitating soft tissue repair.

Injectable and self-healable nano-architectured hydrogel for NIR-light responsive chemo- and photothermal bacterial eradication.

Hydrogels with multifunctional properties activated at specific times have gained significant attention in the biomedical field. As bacterial infections can cause severe complications that negatively impact wound repair, herein, we present the development of a stimuli-responsive, injectable, and in situ-forming hydrogel with antibacterial, self-healing, and drug-delivery properties. In this study, we prepared a Pluronic F-127 (PF127) and sodium alginate (SA)-based hydrogel that can be targeted to a specific tissue via injection. The PF127/SA hydrogel was incorporated with polymeric short-filaments (SFs) containing an anti-inflammatory drug - ketoprofen, and stimuli-responsive polydopamine (PDA) particles. The hydrogel, after injection, could be in situ gelated at the body temperature, showing great in vitro stability and self-healing ability after 4 h of incubation. The SFs and PDA improved the hydrogel injectability and compressive strength. The introduction of PDA significantly accelerated the KET release under near-infrared light exposure and extended its release validity period. The excellent composites' photo-thermal performance led to antibacterial activity against representative Gram-positive and Gram-negative bacteria, resulting in 99.9% E. coli and S. aureus eradication after 10 min of NIR light irradiation. In vitro, fibroblast L929 cell studies confirmed the materials' biocompatibility and paved the way toward further in vivo and clinical application of the system for chronic wound treatments.

In situ forming double-crosslinked hydrogels with highly dispersed short fibers for the treatment of irregular wounds.

In situ forming injectable hydrogels hold great potential for the treatment of irregular wounds. However, their practical applications were hindered by long gelation time, poor mechanical performance, and a lack of a natural extracellular matrix structure. Herein, amino-modified electrospun poly(lactic-co-glycolic acid) (APLGA) short fibers with uniform distribution were introduced into gelatin methacrylate/oxidized dextran (GM/ODex) hydrogels. In comparison with the fiber aggregation structure in the PLGA fiber-incorporated hydrogels, the hydrogels with APLGA fibers possessed a uniform porous structure. The highly dispersed APLGA short fibers accelerated the sol-gel phase transition of the hydrogel due to the formation of dynamic Schiff-base bonds between the fibers and hydrogels. Furthermore, in combination with UV-assisted crosslinking, a rapid gelation time of 90 s was achieved for the double-crosslinked hydrogels. The addition of APLGA short fibers as fillers and the formation of the double-crosslinking network enhanced the mechanical performance of the hydrogels. Furthermore, the fiber-hydrogel composites exhibited favorable injectability, excellent biocompatibility, and improved cell infiltration. In vivo assessment indicated that the GM/ODex-APLGA hydrogels successfully filled the full-thickness defects and improved wound healing. This work demonstrates a promising solution for the treatment of irregular wounds.

Multi-modal thermoacoustic instability suppression via locally resonant and Bragg bandgaps.

Thermoacoustic instability is a common occurrence in combustors, yielding self-sustained oscillations and causing potential risk, such as severe structural damage. In this paper, modal instability suppression inside a duct is studied using periodically arranged membranes within the framework of a linear heat release n-τ model embedded into a fully coupled energy-based model. The periodic arrangement of the membranes along the duct sidewall enables locally resonant and Bragg scattering bandgaps, shown to be conducive for the stabilization of unstable thermoacoustic modes. Eigen-modes are classified into different groups, which call for specific control actions in relation with the bandgap frequencies. While multi-modal instability control of low-order modes can be achieved through the tuning of the resonant bandgaps, the densely packed modal cluster, regrouping modes featuring similar mode shapes, requires proper adjustment of the flame position for avoiding modal instability. Compared with the Bragg bandgaps, locally resonant bandgaps, which should be formed near the unstable modes even without stringent periodicity, are shown to play a decisive role in the control process. Meanwhile, strict periodicity is not necessary for the proposed control strategy, showing the practicability of the proposed control strategy. The study shows a promising route to achieve simultaneous suppression of multi-modal instability.

Influence of boundary conditions on three-dimensional vibration characteristics of thick rectangular plates.

Vibration analysis of the classical elastic structures is not only essential for the study of vibration reduction by predicting the dynamic behavior, but also important to ensure a reliable, safe, and lasting structural performance through the proper design procedure. In this paper, the influence of boundary conditions on the free and forced three-dimensional vibration analysis of thick rectangular plates has been performed using the improved Fourier series method. For the elastically restrained thick rectangular plate, the three-dimensional improved Fourier series displacement forms are used to model the vibration field. The energy formula is employed to describe the three-dimensional dynamics of the plate. All the unknown Fourier series coefficients are then solved by the Rayleigh-Ritz method. In order to validate the proposed model, several numerical examples are provided and compared against the results from the literature and Finite Element Analysis (FEA). In addition, the effects of the boundary restraining spring stiffness and the thickness ratios of thick rectangular plates are analyzed under elastically restrained boundary conditions to develop an in-depth understanding of the three-dimensional vibration characteristics of thick rectangular plates.

Radiation modes and sound radiation from a flexible structure mounted in a duct.

The concept of the radiation modes, originally proposed for free-field problems, has found its widespread use in sound radiation analyses of vibrating structures and their active control applications. In this paper, the sound radiation of a flexible structure, flush-mounted inside a duct in both 2D and 3D configurations, is investigated via an energy-based formulation in conjunction with the near-field integration technique. The structural radiation characteristics are first discussed in terms of modal radiation efficiency, which exhibits obvious oscillating behavior with respect to frequencies, in which symmetric patterns are dominant with smooth variations for small acoustic wavenumbers. Then the interior sound radiation modes are investigated. It is shown that, as compared with their free-space counterparts, the lower-order radiation modes in a duct are more sensitive and prone to be affected by the duct starting from its cut-on frequency. Drastic changes in the radiation mode shapes are observed around the cut-on frequency and each of its multiples/harmonics. Finally, analyses are extended to a coupled panel-duct system. It is observed that, contrary to the free-space case, lower-order radiation modes exhibit predominant variations along the duct length direction, suggesting a possible simplification of the 3D configuration into a 2D one.

Analytical coupled vibro-acoustic modeling of a cavity-backed duct-membrane system with uniform mean flow.

Sound propagation in a flow duct is a complex and technically challenging problem. The presence of flexible vibrating walls inside the duct creates additional difficulties to the problem due to the complex vibro-acoustic and aero-acoustic couplings involved in the system. An accurate prediction of the coupled system response is of great importance for a good understanding of the underlying physics as well as the optimal design of relevant noise suppression devices. In the present work, a unified energy formulation is proposed for the fully coupled structural-acoustic modelling of a duct-mounted membrane backed by an acoustic cavity with a grazing flow. Sufficiently smoothed admissible functions, taking the form of a combination of Fourier series and supplementary polynomials, are constructed to overcome the differential discontinuities for various boundary and/or coupling conditions. The formulation allows the obtention of all relevant vibro-acoustic field information in conjunction with the generalized Lighthill equation and Rayleigh-Ritz procedure. The validation and convergence studies show the accuracy and the efficiency of the proposed model. Results show the strong structural-acoustic interaction in such a duct-membrane-cavity system, and the flow affects resonant amplitude of membrane-dominant modes significantly. Some cross-zones can be observed for the membrane kinetic energy frequency response with low Mach number cases, especially when a higher tension is applied to the membrane. Analyses on the structural-acoustic coupling strength indicate that the coupling between the odd-even structural modes becomes more significant at a higher Mach number compared with odd-odd and even-even mode pairs. It is also shown that adjusting the boundary constraint of the membrane or imposing a higher tensile force allows impairing the adverse influence of the flow in the duct on sound attenuation.

Prediction of break-out sound from a rectangular cavity via an elastically mounted panel.

The break-out sound from a cavity via an elastically mounted panel is predicted in this paper. The vibroacoustic system model is derived based on the so-called spectro-geometric method in which the solution over each sub-domain is invariably expressed as a modified Fourier series expansion. Unlike the traditional modal superposition methods, the continuity of the normal velocities is faithfully enforced on the interfaces between the flexible panel and the (interior and exterior) acoustic media. A fully coupled vibro-acoustic system is obtained by taking into account the strong coupling between the vibration of the elastic panel and the sound fields on the both sides. The typical time-consuming calculations of quadruple integrals encountered in determining the sound power radiation from a panel has been effectively avoided by reducing them, via discrete cosine transform, into a number of single integrals which are subsequently calculated analytically in a closed form. Several numerical examples are presented to validate the system model, understand the effects on the sound transmissions of panel mounting conditions, and demonstrate the dependence on the size of source room of the "measured" transmission loss.

[Effects of celecoxib on the proliferation and apoptosis of human nasopharyngeal carcinoma cell line CNE-2].

OBJECTIVE: To detect the effect of Celecoxib on the proliferation and apoptosis of human nasopharyngeal carcinoma cell line CNE-2. METHOD: The growth inhibition rate of CNE-2 by Celecoxib was evaluated with MTT method. Apoptosis related morphology changes were observed with transmission electron microscopy (TEM). The cell cycle and apoptosis were measured with flow cytometric method (FCM). Apoptotic index (AI) was counted by the TDT-mediated dUTP-biotin nick end-labeling (TUNEL) assay. RESULT: The growth of CNE-2 cell was inhibited by celecoxib in a dose-and time-dependent manner. Apoptosis with nuclear chromatin condensation, cell shrinkage, periplasm loss and the formation of apoptotic bodies was observed with TEM. Apoptotic rates of CNE-2 cells treated with 80 and 100 micromol/L celecoxib were (10.47+/-0.18)% and (20.17+/-0.55)% respectively, significantly higher than those of the control group (1.57+/-0.27)% with FCM. The percentage of G0/G1 phase cells increased, whereas the S and G2/M phases cells decreased in a dose-dependent manner after the treatment. TUNEL assay showed that the apoptosis ratio (AI) of CNE-2 treated with Celecoxib was higher than control group (P<0.01). CONCLUSION: Celecoxib can inhibit the growth of human nasopharyngeal carcinoma cell line CNE-2 and induce the cell apoptosis, which may be related to blocking the cell cycle progress of CNE-2 cells.