Gross anatomy of the gluteal and posterior thigh muscles in koalas based on their innervations

There are not many descriptions of the muscle morphology of marsupials, despite the fact that they should show diversity according to the adaptation and dispersal to a variety of environments. Most of the previous studies regarding the gross anatomy of marsupials were conducted in the 1800 - 1900’s, and many issues still remain that need to be reexamined. For instance, the muscle identification had been performed based only on their attachments and thus, muscle descriptions are often inconsistent among the studies. These classic studies often do not include figures or photographs, so the discrepancies in the descriptions of the muscles could only be verified by performing the muscle identification again with a more reliable method. This problem can be solved by performing muscle identification by innervation. This method, which focuses on the ontogenic origin of the muscle as opposed to the attachment site, is prone to individual and interspecies variation and is a common technique in recent anatomical research. This technique is more reliable than previous methods and is suitable for comparison with other taxa (i.e., eutherians). In this study, we first conducted muscle identification based on innervation in the gluteal and posterior thighs of koalas in order to reorganize the anatomical knowledge of marsupials. This is because the gluteus and posterior thighs of koalas are the areas where previous studies have been particularly inconsistent. We dissected five individual koalas and clarified discrepancies in previous studies, as well as investigated the unique muscle morphology and their function in koalas. Specifically, the koala's gluteal muscle group is suitable for abduction, while the posterior thigh muscles are particularly suitable for flexion. In the future, we will update the anatomical findings of marsupials in the same way to clarify the adaptive dissipation process of marsupials, as well as to contribute to the understanding of the evolutionary morphology of mammals.

Transient buildup and dissipation of a compressed plasma shockwave in arc-discharge plasma beams

Electric propulsion offers the advantage of a high specific impulse through a large exhaust velocity and has seen significant progress in space flight applications. Recently, we observed a transient plasma shockwave during pulsed plasma thruster operation when the plasma beam impacted a probe surface. However, details regarding the plasma shockwave formation are still unknown. This work is an experimental investigation of the compression-induced plasma shockwave in the presence of a planar obstruction. To study the complete shockwave buildup and dissipation process, an ultra-high-speed imaging system was set up to visualize the time-resolved shockwave morphology at a sub-microsecond level. In addition, the local magnetic field and plasma density were measured using 2-D magnetic coils and a triple Langmuir probe, respectively. The successive images of the shockwave give us a comprehensive understanding of the shockwave buildup process. During the 12 μs operational period of the thruster, two shockwaves were formed during the first cycle of the discharge. It is also interesting to note that there is a 1 μs dissipation period between the two shockwaves with the same cloud of plasma compressing against the probe surface. A shockwave model is also developed to predict the appearance of the two shockwaves. The implication is that the local magnetic field strength can be a key indicator for the plasma shockwave buildup and dissipation process.

Viscosity Approximation of PDMS Using Weibull Function

The viscosity of a fluid is one of its basic physico-chemical properties. The modelling of this property as a function of temperature has been the subject of intensive studies. The knowledge of how viscosity and temperature variation are related is particularly important for applications that use the intrinsic friction of fluids to dissipate energy, for example viscous torsional vibration dampers using high viscosity poly(dimethylsiloxane) as a damping factor. This article presents a new method for approximating the dynamic viscosity of poly(dimethylsiloxane). It is based on the three-parameter Weibull function that far better reflects the relationship between viscosity and temperature compared with the models used so far. Accurate mapping of dynamic viscosity is vitally important from the point of view of the construction of viscous dampers, as it allows for accurate estimation of their efficiency in the energy dissipation process.

Improved Sound Absorption Properties in Polyurethane Foams by the Inclusion of Al2O3 Nanoparticles

At present, the scale of China’s power grid is becoming larger and larger, and the control of low-frequency noise in substations (especially for transformers) is very important. The sound-absorbing materials have become one of the important ways to control low-frequency noise. The single polyurethane material cannot satisfy the requirements for reducing low-frequency noise, so it is very necessary to study its composite with other materials. In the paper, the flexible polyurethane foam and Al2O3 nanoparticle composites were obtained by the impregnation method. The method was simple, safe, and easy to control. The morphology and sound absorption coefficient of the foam materials before and after filling were analyzed. Single-hole acoustic cavity models of PU and Al2O3-PU composite were established through the finite element. The absorption and dissipation process of sound pressure for single hole was studied to understand the energy dissipation process. Meanwhile, through studying acoustic energy storage and acoustic energy dissipation, the loss factor of a single hole was obtained, which can predict the change rule of the sound absorption coefficient for PU foam and Al2O3-PU.

Digital Image Disintegration Analysis: a Novel Quality Control Method for Fast Disintegrating Tablets

Measuring tablet disintegration is essential for quality control purposes; however, no established method adequately accounts for the timeframe or small volumes of the medium associated with the dissipation process for fast disintegrating tablets (FDTs) in the mouth. We hypothesised that digital imaging to measure disintegration in a low volume of the medium might discriminate between different types of FTD formulation. A digital image disintegration analysis (DIDA) was designed to measure tablet disintegration in 0.05–0.7 mL of medium. A temperature-controlled black vessel was 3D-printed to match the dimensions of each tablet under investigation. An overhead camera recorded the mean grey value of the tablet as a measure of the percentage of the formulation which remained intact as a function of time. Imodium Instants, Nurofen Meltlets and a developmental freeze-dried pilocarpine formulation were investigated. The imaging approach proved effective in discriminating the disintegration of different tablets (p < 0.05). For example, 10 s after 0.7 mL of a saliva simulant was applied, 2.0 ± 0.3% of the new pilocarpine tablet remained, whereas at the same time point, 22 ± 9% of the Imodium Instants had not undergone disintegration (temperature within the vessel was 37 ± 0.5°C). Nurofen Meltlets were observed to swell and showed a percentage recovery of 120.7 ± 2.4% and 135.0 ± 6.1% when 0.05 mL and 0.7 mL volumes were used, respectively. Thus, the new digital image disintegration analysis, DIDA, reported here effectively evaluated fast disintegrating tablets and has the potential as a quality control method for such formulations.

Laboratory data on wave propagation through vegetation with following and opposing currents

Coastal vegetation has been increasingly recognized as effective buffer against wind waves. Recent studies have advanced our understanding of wave dissipation process in vegetation (WDV). In intertidal environments, waves commonly propagate into vegetation fields with underlying tidal currents, which may alter WDV, but such influence is often overlooked. The key mechanism of WDV with co-existing currents are understudied, as previous studies have drawn contradictory conclusions on the effect of following currents on WDV. Subsequent laboratory experiments have partly explained the inconsistent conclusions, but relevant data are rarely available for theoretical or modelling development. Additionally, while the vegetation drag coefficient is a key factor influencing WDV, it is rarely reported for combined wave-current flows. This paper reports a unique dataset from two flume experiments, including 668 wave-only and wave with following/opposing current tests. A variety of data including wave height, drag coefficient, in-canopy velocity and acting force on mimic vegetation stem are recorded. This dataset is expected to assist future theoretical advancement on WDV, which may ultimately lead to more accurate prediction of wave dissipation capacity of real coastal wetlands. The dataset is available from figshare (https://doi.org/10.6084/m9.figshare.13026530.v2; Hu et al., 2020) with clear instructions for reuse. The current dataset will expand with additional WDV data from ongoing as well as planned future observation in real mangrove wetlands.

Formation mechanism and chaotic reinforcement elimination of the mechanical stirring isolated mixed region

The isolated mixed region (IMR) is gradually formed during stirring and reduces the mixing efficiency. The unsteady-state formation process of the IMR was modeled and its formation mechanism was analyzed. The rotating frequency of the impeller was optimized using the chaos mathematical theory to improve the stirring efficiency without increasing the power consumption. The calculated results demonstrate that the IMR is a coherent structure, and its formation process is based on the free shear effect of the mixed layer. The chaotic stirring method can accelerate the momentum dissipation process by 37% by eliminating the IMR, and increase the speed by up to 31%. Therefore, chaotic mixing can eliminate the IMR in a shorter time and lower the power consumption.