An ex-vivo validation of the modulus-length framework to characterize passive elastic properties of skeletal muscle.

The passive elastic properties of skeletal muscles are related closely to muscle extensibility and flexibility. Recently, a single probe setup has been reported that measures the passive elastic properties of muscles in vivo. This uses a modulus-length framework to investigate sensitive dynamic parameters, termed as passive elastic coefficient k, slack length l0, and slack shear modulus G0 to quantify the passive elastic properties of human muscle. In particular, the parameter k calculated based on this framework reflects the change rate of the local shear modulus with respect to the muscle length, which remains constant during the entire passive stretching process. In this report, the modulus-length framework was validated in four groups of ex-vivo muscle samples (young and old chickens, pork, and beef). All the muscle samples were stretched mechanically whilst muscle length was monitored and recorded with simultaneous measurement of dynamic shear wave elastography (SWE). Agreement analyses using Bland-Altman diagrams and intraclass correlation coefficients (ICC) were then performed on coefficient k values obtained by mechanical stretching (k1) and real-time ultrasound imaging methods (k2). Bland-Altman diagrams show that the majority of the points lie within the 95 % LoA ([-1.87, 2.29]; p = 0.276) and the level of reliability was "good" to "excellent" based on the ICC results (ICC, 0.904; 95 % confidence interval, 0.813-0.953). This indicated that the ultrasound and mechanical methods produced very similar results. Meanwhile, the range of the coefficient k values in four muscle types and groups was significantly different (p < 0.05), a finding which strongly supports the potential use of this coefficient to characterize muscle quality and status.

Fabrication and microstructure of quartz ceramics with orderly-arranged carbon filler.

Ceramics with tailored pore structure are showing potential applications in some special fields. For fabricating quartz ceramics with orderly-arranged carbon filler, a combination of 3D printing, vacuum suction filtration and sintering was explored to fabricate quartz ceramics with highly-ordered and well-connected big pore channels. The spatial lattice structure in the polylactic acid (PLA) template fabricated by 3D printing together with raw material ratio and sintering temperature has great effect on the properties and pore structure of the porous quartz ceramics. To demonstrate the technical feasibility for fabricating quartz ceramics with orderly-arranged filler, carbon powder was taken as an example and fully filled in the big pore channels of the porous quartz ceramics via vacuum impregnation method. By choosing the quartz ceramics with only highly-ordered and well-connected big pore channels as substrate, quartz ceramics with orderly-arranged carbon filler were successfully obtained.