Biotribology最新文献

Among the cosmetic forms used to administer cosmetic actives, the gel form has been highly sought after, as it offers a non-greasy sensation and allows the application of the formulation associated with ultrasound techniques for skin rejuvenation, such as phonophoresis. The aim of the present study was to develop a stable system for delivering anti-aging actives to the skin containing niacinamide and saccharide isomerate. The formulation and base development stage included a stability and rheological study over 16 weeks. The rheological analysis consisted of steady-state flow measurements and amplitude sweep tests, followed by a frequency sweep test. Three-interval thixotropy testing (3ITT) was also performed. As a result, the developed system showed high stability throughout the 16-week period. The organoleptic and rheological stability profile of the base and the formulation was quite similar, indicating that the presence of actives is indifferent to gel stability. Furthermore, rheologically, the base and the formulation exhibited shear-thinning behavior. The addition of the actives in the formulation decreased the apparent viscosity value by nearly half of the original value. Strong viscoelastic behavior was evidenced in both samples. In the end, the 3ITT test revealed a high recovery of sample viscosity. It can be concluded that the developed gel is a promising formulation for the topical administration of the studied actives.

Wooden journal bearing is widely used in various applications such as wind turbines and marine bearings. In this paper, the wooden journal bearings is fabricated with teak wood due to their higher strength and durability. Various manufacturing operations such as cutting, turning, etc., are performed during the fabrication process of wooden journal bearings. After fabricating it, the experimental study is performed to analyze the influence of operating parameters on the tribological characteristics of wooden bearings. For this, the operating parameters such as speed and load are considered input variables. Whereas, the tribological characteristics of wooden bearings such as wear resistance and surface roughness are considered the output parameters. The major aim of this study is to analyze and optimize the tribological characteristics of wooden bearings. This can be achieved by increasing its wear resistance and increasing surface roughness. By using the response surface methodology (RSM), the influence of operating parameters (i.e. speed and load) on the tribological characteristics of wooden bearings are analyzed. Furthermore, the desirability function is used to obtain the optimal tribological characteristics of wooden bearings. These results show that speed is the most significant parameter for wear resistance and load for surface roughness of wooden bearings. Due to continuous operation, the wear rate of wooden bearings first increases and then decreases. In addition, the surface roughness of wooden bearings becomes smooth. The regression analysis develops the mathematical relationship between the operating parameters and the tribological characteristics of wooden bearings.

Dry mouth is a troublesome condition linked to lubrication failure and leads to other diseases such as fungal infections and wounds in the oral cavity. There are many commercial salivary substitutes in the market, but none with a long-lasting lubrication effect. Polymer-coated liposomes can be an interesting formulation strategy for retrieving the symptoms of dry mouth by mimicking the micelles of saliva. In the present study, polymer coated-liposomes were prepared by the conventional thin film method and subsequently coated with three different polymers with different charge densities; alginate, chitosan and hydrophobically modified ethyl hydroxyethyl cellulose (HM-EHEC). The prepared polymer-coated liposomes were studied concerning their lubricating properties using a ball-on-disc tribometer at 2 N load at 37 °C, and their flow behaviours were also measured. Solutions of the pure polymers and dispersions of the uncoated liposomes were also studied to investigate any contributions from the individual components. A commercial dry mouth product based on HEC (hydroxyethyl cellulose) and glycerol was also included. The formulations were measured as soon as possible after preparation and some of them after >4 weeks. Results demonstrated that all the positively-charged formulations (chitosan, positive liposomes and chitosan-coated liposomes) had superior lubricating properties with friction coefficients (μ < 0.1) at orally relevant speeds (50 mm/s) as compared to the neutral or negatively-charged systems. At boundary lubrication conditions (3 mm/s), the chitosan-coated liposomes obtained an even lower friction force than the individual components, thus indicating a synergistic effect between the polymer and the liposome.