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Study on friction behavior at the interface between prosthetic socket and liner

Xie Jingyang, Liu Xidong, Tang Jianhua, Li Xi, Li Wei

Acta of Bioengineering and Biomechanics

2021

Vol. 23, no. 1

83--93

Purpose: The friction characteristics at the interface between prosthetic socket and liner have an important influence on the walking function and wearing comfort of amputees. The frictional behavior at the prosthetic socket/liner interface can provide theoretical guidance for the design and selection of prosthetic materials. So it is of great significance to study the friction behavior at prosthetic socket/liner interface. Methods: The surface roughnesses of the prosthetic socket and liner materials were measured by a laser confocal microscope. The frictional behavior at the prosthetic socket/liner interface was studied on a UMT TriboLab Tribometer by simulating the reciprocating sliding contact mode. An infrared camera was used to take thermal images and then calculated the temperature increase at the socket/liner interface. Results: The coefficient of friction of the silicon rubber fabric are significantly smaller than that of the foam liner materials. The frictional energy dissipation at the liner/acrylic socket interface is the smallest, while it is greater for 3D-printed socket materials. Meanwhile, the temperature increase has a positive correlation to the coefficient of friction and frictional energy dissipation. Conclusions: The three kinds of 3D-printed materials with high surface roughness have higher interface coefficient of friction and energy dissipation than acrylic material. The stiffness and energy consumption play an important role in the interface friction characteristics of the prosthetic liner materials. The appropriate coefficient of friction at the surface between prosthetic socket and liner is essential. A type of the reinforcement fiber has influence on the friction behavior of the 3D-printed reinforced nylon.

Study on pharmacokinetics, tissue distribution, and excretion of phloretin and its prodrug 2′,4′,6′,4-Tetra-O-acetylphloretin in rats using LC–MS/MS

Wang Libin, Li Xi, Mi Le, Shen Xin, Feng Tian, Liu Xueying, Wang Qingwei

Acta Chromatographica

2019

Vol. 31, no. 1

63--70

2′,4′,6′,4-Tetra-O-acetylphloretin (TAPHL) is a prodrug of phloretin (PHL) in which the OH groups are protected by acetylation. A validated liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the determination of PHL in rat biological matrices was developed and applied to investigate and compare the pharmacokinetics, tissue distribution, and excretion of PHL and TAPHL in rats following a single oral administration. The method was validated for accuracy, precision, linearity, range, selectivity, lower limit of quantification (LLOQ), recovery, and matrix effect. All validation parameters met the acceptance criteria according to regulatory guidelines. The mean pharmacokinetic parameters of tmax, Cmax, AUC(0 − t), CL/F, and t1/2 were observed after oral administration in rats. The data showed that PHL was absorbed and eliminated rapidly from plasma after oral administration. The pharmacokinetic properties are improved, such as the tmax has been prolonged and the area under the curve (AUC) has been enhanced after oral administration of TAPHL to rats. Tissue distribution results indicated that PHL could be rapidly and widely distributed into tissues but could not effectively cross the blood–brain barrier in rats. After oral administration of TAPHL to rats, its tissue distribution to rats was similar as that after oral administration of equimolar PHL. In addition, higher recoveries of PHL following administration of TAPHL indicated that TAPHL might reduce the excretion of PHL from the body by reducing the first pass effect.