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This study involves the preparation of hybrid bio-composites using the hand lay-up method, with epoxy resin serving as the matrix and natural fibers as the reinforcement. The primary objective was to conduct a mechanical and tribological analysis of jute–coir and banana–coir hybrid composites, as well as neat coir bio-composites. The results indicated that the jute–coir hybrid composite exhibited the lowest water absorption (7.6%) and thickness swelling (6.8%) when compared to the banana–coir and neat coir bio-composites. Moreover, the jute–coir composites demonstrated superior hardness and strength, with a higher hardness (78HRB) and tensile strength (120MPa) compared to other bio-composites. Furthermore, sliding and erosion wear tests demonstrated that the jute–coir bio-composite displayed excellent resistance to abrasion and erosion under various wear conditions. As a result, the jute–coir composite, with its reduced thickness swelling and water absorption and favorable mechanical and tribological properties, holds potential for application in diverse areas such as railway coach interiors, aircraft industries for interior components, as well as everyday items like plates and spoons.

The microstructural modifications due to high energy electrons (8–18 MeV) and their correlation with the yielding behavior of polycrystalline nickel have been investigated. The specimens in the form of strips were irradiated at room temperature for 15 min in the energy range 8–18 MeV using linear accelerator. The comparison of microstructural results of irradiated specimens with that of the un-irradiated ones reveals that radiation deteriorate the surface of the target specimens. The damage was found to be more prominent at the grain boundaries. The tensile tests of both unirradiated and irradiated samples were carried out using Universal Testing Machine at room temperature. An increase in yield stress and loss of ductility was observed in case of irradiated specimens, which became more pronounced with an increase of incident beam energy. These effects are attributed to the interaction of glide dislocations stress fields with the defects produced during irradiation.

Clavicle has a number of peculiar features in the human skeleton. It is the only long bone lying horizontally and the first bone to begin ossification, among other features. It is also a peculiar and unusual site for an expansile lytic lesion which, if present, would raise multiple diagnostic possibilities. We present this unusual case of an expansile lytic lesion in the medial end of clavicle in an adolescent girl and the possible differential diagnoses.

A theoretical model for corneal swelling with respect to aqueous inflow, based on corneal dimensions and mechanical and chemical properties, is presented in this paper. The mechanical properties of the corneal stroma, with respect to aqueous inflow, are considered in the basis of swelling mechanics. Equations describing the time course of swelling are also given. With this formulation, we can explain how glaucoma may result if outflow facility decreases faster compared to aqueous inflow. The opposite situation, e.g. of hypotony, may also be considered.

Aqueous nanosilica sol (particle size range: 9–13 nm, pH: 9.0) was added at various low concentration range (0.5–2 wt.%) into aqueous poly (vinyl alcohol) (PVA) of different molecular weight (98% hydrolyzed, 20 wt.%) (pH: 5.0) at room temperature under constant stirring to synthesize organic-inorganic hybrid hydrogels in presence of sodium lauryl sulphate as a silica dispersant. Buffer tablets were added to arrest the pH at 9.0 (to prevent any silica aggregation due to change in pH). The resultant hybrids were cast on Teflon sheets and dried in an oven at 50°C to drive out all the unbound water. Those films were then subjected to freese-thaw treatment continuously for 5 h. The freese-thawed films appeared opaque. The swelling-de swelling experiments with the hydrogels were carried out in distilled water at room temperature and consequently allowed to de-swell naturally. Those observations were correlated with the microstructures of the hybrid hydrogels.

Swelling property of acrylamide hydrogels, prepared from aqueous solutions of acrylamide monomer having concentrations in the range of 10–60 wt% by γ-ray irradiation method using a Co-60 gamma radiation source at doses ranging 1–30.0 kGy, has been investigated under various swelling media. These swelling media were basically solvents (solutions), produced by dissolving methanol, ethanol, glucose, sucrose, sodium chloride and sodium persulfate individually with distilled water, and solutions prepared with pHs = 3, 7 and 10. The investigation was performed in order to observe the effect of these solvents and pHs as well as the influence of monomer concentrations, radiation doses and times on swelling behavior of hydrogels. Swelling values were found higher for hydrogels prepared with lower monomer concentrations (ca. 20 wt%) and radiation doses (ca. 5 kGy) and showed a leveling off tendency within 24 h. The glucose solvent and the buffer solution of pH = 10 revealed significant increase of swelling of hydrogels as compared to other solutions. Results are explained based on crosslinking density in hydrogel, polymer-solvent/polymer-polymer interactions in solutions, permeability of molecules in solutions and ionization capacity of hydrogel in pH.

One of the unique properties of polymeric gel is that the volume and shape of gel can dramatically change even at mild variation of external stimuli. Though a variety of instability patterns of slender and thin film gel structures due to swelling have been observed in various experimental studies, many are not well understood. This paper presents the analytical solutions of swelling-induced instability of various slender and thin film gel structures. We have adopted the well developed constitutive relation of inhomogeneous field theory of a polymeric network in equilibrium with a solvent and mechanical load or constraint with the incremental modulus concept for slender beam and thin film gel structures. The formulas of buckling and wrinkle conditions and critical stress values are derived for slender beam and thin film gel structures under swelling-induced instability using nonlinear buckling theories of beam and thin film structures. For slender beam structure, we construct the stability diagram with the distinct stable and unstable zones. The critical slenderness ratio and corresponding critical stresses are provided for different dimensionless material parameters. For thin film gel structures, we consider the thin film gel on an elastic foundation with different stiffness. The analytical solutions of critical stress and corresponding wrinkle wavelength, as well as buckling condition (or critical chemical potential) are given. These analytical solutions will provide a guideline for gel structure design used in polymeric gels MEMS and NEMS structures such as sensors and actuators. More importantly, the work provides a theoretical foundation of gel structure buckling and wrinkle, instability phenomena are different from normal engineering or material buckling.

A polymer network can imbibe copious amounts of solvent (water) and swell, and the resulting state is known as a hydrogel. In this study, we have made the modification for the all-atom consistent valence force field (CVFF) to investigate the swelling property of polyacrylamide (PAM) hydrogel by molecular dynamics simulation. We have built 21 hydrogel models with different solvent contents and calculate the average chemical potential and diffusion coefficient of solvent molecules in PAM hydrogel. We find that when the mass fraction of solvent is about 90%, PAM hydrogel reaches its free swelling limitation and loses the motivation of absorbing solvent. Furthermore, it is also found that PAM hydrogel has a phase transition phenomenon when the values of solvent chemical potential are between $-23.4$kcal/mol and $-20.4$kcal/mol. This study will provide insight into the basic parameters which are widely used in continuum mechanics analysis of hydrogels from atomic point of view and help researchers to improve the continuum mechanics model for neutral hydrogel.

Soft active camouflage has been developed in different routes. The current study introduces an updated method by using metal complex within a polyelectrolyte film. Ions of [Ni Tmeda Hacac]$+$ were synthesized and incorporated into Nafion film, forming a solvatochromic responsive polyelectrolyte material. Under solvent environment, this polyelectrolyte gel changed its color from red to green, and was then bleached by heating. The mechanism is explained via the molecular coordination theory. Effect of solvent diffusion was studied experimentally by recording the progress and theoretically by establishing a multi-physics model. Two swelling processes were identified, coloration swelling (C-swelling) and dilution swelling (D-swelling). Wavelength and absorbance in light intensity are characterized by considering the material property and mechanical configuration. The results demonstrate the capability of flexible active camouflage using the Nafion-metal complex composites.

If gel swells in binary solvents, two unusual phenomena may appear. Two solvents with relatively low swelling ability may become a good solvent for the polymer with high swelling ability when mixed, which is known as a cosolvency effect. In contrast, a cononsolvency effect indicates polymer is less soluable in solvent mixtures than it is in each of the cosolvents. In this work, we develop a thermodynamic theory to describe the equilibrium swelling behaviors of gels in binary solvents based on the Flory–Huggins lattice model. The model can reproduce both cosolvency and cononsolvency effects, showing that these effects are caused by the preferential absorption of the solvent by polymer together with solvent–solvent interactions. The model is also applied to describe experimentally observed cosolvency and cononsolvency effects in the literature, which shows an acceptable agreement.

Background: Tourniquet use during upper extremity surgery in patients with a history of axillary lymph node dissection (ALND) remains controversial due to the perceived but unproven risk of lymphoedema. We prospectively evaluated upper extremity swelling in patients with a history of unilateral ALND using a standardised tourniquet model.

Methods: A tourniquet was applied to the upper arm bilaterally, with the unaffected side serving as an internal control. Each arm was subsequently held in an elevated position to reduce swelling. Hand volume was measured using an aqueous volumeter.

Results: The patients’ ALND arms experienced slightly greater increases in volume following tourniquet application compared to their healthy control arms. However, this amount of oedema was temporary and reversible, as both arms experienced spontaneous resolution of swelling with no significant difference in residual hand volume at the conclusion of the study.

Conclusions: Tourniquet use may be safe in patients with a history of ALND. Further investigation is needed to verify this in a surgical setting.

Level of Evidence: Level II (Therapeutic)