Finite Element Vibration Analysis of a Functionally Graded Plate

Functionally Graded (FG) materials are recent types of engineering materials Fdeveloped as a solution for applications where a couple of relevant properties of different materials are desired in a single continuous composite structure. In these materials, properties are patterned in a way to insure a gradient and continuous property transition direction-wise. This study is a contribution in the literature among other studies but provides an additional understanding of FG Plate structures vibrational behavior in terms of natural frequencies and modal shapes. For this end, an FG plate is modelized and analyzed using AnsysAPDL. Two boundary conditions (all sides clamped “CCCC” and two parallel sides clamped with two others free “CCFF”) for the same plate element and two power law indices “n” are considered. Results are compared with those in the literature and conclusions are drawn accordingly.

Fabrication and Biocompatibility Evaluation of Nanodiamonds-Gelatin Electrospun Materials Designed for Prospective Tissue Regeneration Applications

Due to the reduced ability of most harmed tissues to self-regenerate, new strategies are being developed in order to promote self-repair assisted or not by biomaterials, among these tissue engineering (TE). Human adipose-derived mesenchymal stem cells (hASCs) currently represent a promising tool for tissue reconstruction, due to their low immunogenicity, high differentiation potential to multiple cell types and easy harvesting. Gelatin is a natural biocompatible polymer used for regenerative applications, while nanodiamond particles (NDs) are used as reinforcing nanomaterial that might modulate cell behavior, namely cell adhesion, viability, and proliferation. The development of electrospun microfibers loaded with NDs is expected to allow nanomechanical sensing due to local modifications of both nanostructure and stiffness. Two aqueous suspensions with 0.5 and 1% w/v NDs in gelatin from cold water fish skin (FG) were used to generate electrospun meshes. Advanced morpho- and micro-structural characterization revealed homogeneous microfibers. Nanoindentation tests confirmed the reinforcing effect of NDs. Biocompatibility assays showed an increased viability and proliferation profile of hASCs in contact with FG_NDs, correlated with very low cytotoxic effects of the materials. Moreover, hASCs developed an elongated cytoskeleton, suggesting that NDs addition to FG materials encouraged cell adhesion. This study showed the FG_NDs fibrous scaffolds potential for advanced TE applications.

Tunable Two-Way Unidirectional Acoustic Diodes: Design and Simulation

Predeformation simultaneously changes the effective material stiffness as well as the geometric configuration and therefore may be utilized to tune wave propagation in soft phononic crystals (PCs). Moreover, the band gaps of soft PCs, as compared with those of the hard ones, are more sensitive to the external mechanical stimuli. A one-dimensional tunable soft acoustic diode based on soft functionally graded (FG) PCs is proposed. The two-way asymmetric propagation behavior is studied at the resonant frequency within the band gap. Numerical results show that the operating frequency (i.e., the resonant peak) of the soft graded acoustic diode can be altered by adjusting the mechanical biasing fields (including the longitudinal prestress and the lateral equibiaxial tension). The adjustment becomes significant when the strain-stiffening effect of the Gent hyperelastic material is properly harnessed. Furthermore, the prestress or equibiaxial tension can affect the two-way filtering of the soft FG PC in a separate and different manner. In addition, it is much easier to realize the tunable acoustic diode by exploiting soft FG materials with stronger compressibility. It is shown that the introduction of acoustic impedance is beneficial for predicting the tunable effects. The simulations and conclusions should provide a solid guidance for the design of tunable two-way unidirectional acoustic diodes made from soft hyperelastic materials.

Comparison of conventional dressings and vacuum-assisted closure in the wound therapy of Fournier’s gangrene

Objective: The purpose of our study was to compare Vacuum-assisted closure (VAC) and conventional dressings in the wound therapy of Fournier’s gangrene (FG). Materials and methods: The study evaluated 54 patients, retrospectively. Following initial removal of necrotic and devitalized tissue, in Group I patients the wounds were covered with conventional antiseptic dressings and patients continued to be treated with conventional dressings. In Group II patients VAC therapy was initiated. The collected data were compared between groups. Results: The difference between two groups were statistically significant in terms of number of daily dressing (group I: 2, group II: 0,5), VAS (group I: 8, group II: 5), number of daily analgesics (group I: 4, group II: 2), number of daily narcotic analgesics (group I: 1, group II: 0), duration of mobilization per day (group I: 40, group II: 73 minutes) (p < 0.05). Conclusions: Our study does not determine that a VAC therapy is better than conventional dressings in terms of clinical outcome. However, vacuum dressing appears an effective and successful method, which offers fewer dressing changes, less pain, and greater mobility comparing to conventional dressings in the management of FG patients.