Search

Artificial muscle is one of the more prominent topics in modern robotics as it can be applied to robotic arms, electric vehicles and wearable robots (Shahinpoor et al. in Smart Mater Struct 7:15–30, 1998; Jani et al. in Mater Des 56:1078–1113, 2014). The advantages of Shape Memory Alloy (SMA) artificial muscle are lightness and high energy density. The high energy density allows the actuator to make powerful motions. Meanwhile, SMA wire contracts 6% of its length, which means that the required displacement cannot be achieved by a simple connection. To resolve these disadvantages, the SMA wires are coiled in a diamond-shaped structure. If the electric current is given by contracting wires in the longitudinal direction, the actuator can exert force and displacement in the diagonal direction. As the crossed tendon finds its minimal length when actuated, the rotation angle converges to 90°. Parameters related with the rotating motion were selected, such as SMA wires’ diameter and length, distance between the crossed part and elbow part, size of the diamond-shaped structure, friction, etc. To determine the maximum force of the actuator, a graphical method was used, which is similar to the yield strength determination (0.2% offset). Because the robotic elbow joint is connected by the tendon, the connections between links are flexible, and without motor it does not generate any sound or noise during operation. The robotic elbow joint using the SMA actuator is designed and analyzed, which can rotate 86.7° and generates maximum 56.3 N force.

Tumor necrosis factor-α (TNF-α) plays an important role in inflammatory responses. Deregulated activation of TNF-α signaling is associated with various inflammatory diseases. In view of the finding that the seventy percent ethanol extract of Litsea japonica (LJE) interferes with TNF-α-induced NF-κB activation, activity- guided fractionation was performed to identify the active components of the extract. The EtOAc, CH2Cl2 and n-Hexane fractions of LJE induced suppression of inhibitor of κB (IκB) kinase (IKK), p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK), and significant reduction of TNF-α- induced NF-κB activation. From the CH2Cl2 fraction, hamabiwalactone A, hamabiwalactone B, litsenolide B2 and litsenolide C2 were identified to inhibit TNF- α-induced NF-κB activation. The cytotoxic activities of these lactone compounds were additionally evaluated.

The design space for morphing wings is incredibly broad and allows for a wide range of improvements versus fixed wing aircrafts such that each type of morphing can be useful for different purposes. This work introduces a novel concept for a twist morphing wing segment where only a segment of the wing is actuated which causes a rotation of the tip of the wing while the base segment fixed. The morphing segment consists of a smart soft composite structure made from PDMS and PLA which is actuated by multiple embedded SMA wires. This structure was implemented in a UAV-sized wing and was tested both in still-air conditions and in an open-type wind tunnel to determine the actual impact of this mode of actuation. Results show that this concept can improve the aerodynamic properties of the wing, particularly at low angles of attack.

This paper introduces a novel geometry for a pure-twisting soft morphing actuator that improves the stability of the actuator and allows it to obtain a larger twisting angle. The smart soft composite (SSC) actuator uses pair of NiTi shape memory alloy (SMA) wires embedded in a cross-shaped polydimethylsiloxane (PDMS) matrix at constant and opposite eccentricity across the cross-section in opposite directions in order to produce a twisting motion. To evaluate the twisting performance of the cross-shaped actuator, specimens with rectangular cross-sections and cross-shaped cross-sections are made and their twist angles are measured and compared. Results show that the cross-shaped actuator is capable of a higher twisting rate by using a thinner flange due to a more stable twisting motion.

In this paper, biomimetic underwater robots built using smart actuators, e.g., a shape memory alloy (SMA), an ionic polymer metal composite (IPMC), lead zirconate titanate (PZT), or a hybrid SMA and IPMC actuator, are reviewed. The effects of underwater environment were also considered because smart actuators are often affected by their external environment. The characteristics of smart actuators are described based on their actuating conditions and motion types. Underwater robots are classified based on different swimming modes. We expanded our classification to non-fish creatures based on their swimming modes. The five swimming modes are body/caudal actuation oscillatory (BCA-O), body/caudal actuation undulatory (BCA-U), median/paired actuation oscillatory (MPA-O), median/paired actuation undulatory (MPA-U), and jet propulsion (JET). The trends of biomimetic underwater robots were analyzed based on robot speed (body length per second, BL/s). For speed per body length, robots using an SMA as an actuator are faster than robots using an IPMC when considering a similar length or weight. Robots using a DC motor are longer while their speeds per body length are similar, which means that robots using smart actuators have an advantage of compactness. Finally, robots (using smart actuators or a motor) were compared with underwater animals according to their speed and different swimming modes. This review will help in setting guidelines for the development of future biomimetic underwater robots, especially those that use smart actuators.

Korean ginseng (Panax ginseng C.A. Meyer) contains several types of saponins and ginsenosides, which are usually considered the major active components of ginseng. The types and quantities of saponins found in ginseng may differ depending on the region of cultivation. As a result, ginsengs produced in different areas of Korea have been unintentionally mislabeled and/or confused by Korean herbal markets owing to their complicated plant sources. Another concern is that 4- and 6-year-old ginseng roots, traditionally prescribed for different medicinal purposes, can vary in total saponin contents. Therefore, it is necessary to establish a reliable method for distinguishing different cultivation regions and ages of ginseng roots. A rapid resolution liquid chromatography-quadruple time of flight mass spectrometry (RRLC-QTOF/MS) based chemical profiling method was established for the rapid and global evaluation of Korean ginseng roots in this study. The method was successfully applied for the comparison of ginseng roots cultivated in different regions and of differing ages. Principal component analysis (PCA) of the data showed the clear separation of 4- and 6-year-old ginseng roots and of ginseng cultivated in 2 different areas of Korea, Ganghwa and Punggi.

Samples of the edible seaweed, sea mustard (Undaria pinnatifida) were extracted with 80% aqueous methanol, and the concentrated extract was partitioned with ethyl acetate, n-butanol, and water, successively. Isolated fucosterol (1) from the ethyl acetate layers using repeated silica gel and octadecyl silica gel (C18, ODS-A) column chromatography and identified it using spectroscopic data including NMR, MS, and infrared spectroscopy (IR). Osteoclasts are specialized multinucleated cells with bone resorbing activity. The induction of c-Fos and NFATc1 transcription factors by receptor activator of nuclear factor κB ligand (RANKL) is a key event in osteoclast differentiation. Isolated and identification compound 1 was investigated in vitro for their anti-osteoclastic activity. Compound 1 inhibited osteoclastic differentiation in a dose-dependent manner without cytotoxicity. In addition, the inhibitory mechanisms of compound 1 were investigated. Compound 1 induced a clear reduction in the expressions of NFATc1 and c-Fos upon RANKL stimulation. In summary, compound 1 from sea mustard showed anti-osteoporotic potential.

Enterobacter amnigenus GG0461, isolated and identified from greenhouse soils, has a high activity of nitrate uptake in the Pseudomonas agar factor medium. Although nitrate is not essential for the growth of this microorganism, it increases the growth rate. To characterize the microbial nitrate uptake, we measured the effect of chlorate on the uptake, since chlorate is an inhibitor of plant nitrate uptake. In the absence of nitrate, the growth of E. amnigenus was inhibited by chlorate at concentrations higher than 1 mM. In the presence of 50 mM nitrate, nitrate uptake was completely inhibited by 30 mM of chlorate, and growth was suppressed by chlorate at concentrations above 10 mM. In the presence of chlorate, the growth and nitrate uptake gradually improved when nitrate concentration increased. To overcome the inhibitory effect of chlorate, the nitrate concentration was required to be 2.5 times higher than that of chlorate, suggesting that there exists competition between chlorate and nitrate for the binding site of the nitrate transporter. Chlorate-induced inhibitions of bacterial nitrate uptake and growth seemed to have different mechanisms: a competitive inhibition in the former case and the formation of chlorite, a toxic reduced metabolite of chlorate, in the latter case.

A new compound, miroestrol-3-O-β-D-glucopyranoside, was isolated from the roots of Pueraria mirifica (white kwao krua). The structure of the compound was established on the basis of NMR, ESI-MS, and IR spectroscopic data.