The development of a position control system for a shape memory alloy (SMA) wire actuator using an electrical resistance feedback is presented in this paper. A novel control scheme is implemented to eliminate the need for a position sensor to achieve stable and accurate positioning by utilizing the actuator's electrical resistance feedback. Experiments are conducted to investigate the relationship between electrical resistance and displacement using an SMA wire test setup. Due to the highly nonlinear behavior of the SMA actuator, a neural network is employed to model the relationship and to predict the position of the actuator using only the electrical resistance. Feedback control of the SMA is achieved by using a proportional-derivative (PD) controller. Experimental results demonstrate that the proposed position control system achieves good control performance without using a position sensor.

The target of rapamycin (TOR) is a highly conserved protein kinase that regulates cell growth and metabolism. Here we performed a genome-wide screen to identify negative regulators of TOR complex 1 (TORC1) in Schizosaccharomyces pombe by isolating mutants that phenocopy Dtsc2, in which TORC1 signaling is known to be up-regulated. We discovered that Dnpr2 displayed similar phenotypes to Dtsc2 in terms of amino acid uptake defects and mislocalization of the Cat1 permease. However, Dnpr2 and Dtsc2 clearly showed different phenotypes in terms of rapamycin supersensitivity and Isp5 transcription upon various treatments. Furthermore, we showed that Tor2 controls amino acid homeostasis at the transcriptional and post-transcriptional levels. Our data reveal that both Npr2 and Tsc2 negatively regulate TORC1 signaling, and Npr2, but not Tsc2, may be involved in the feedback loop of a nutrient-sensing pathway.T HE target of rapamycin (TOR) plays vitally important roles in regulating cell growth and metabolism. TOR interacts with several proteins to form two structurally and functionally distinct complexes named TOR complex 1 (TORC1) and 2 (TORC2) Sabatini 2009, 2012). In response to environmental cues, TORC1 controls cell growth and differentiation by coordinating diverse cellular processes including transcription, translation, and autophagy. Research on TORC1 has generated a model of the complex TOR signaling network (Huang and Manning 2009;Orlova and Crino 2010;Laplante and Sabatini 2012). In the regulation of TORC1 signaling, four major signals have been identified, namely growth factors (insulin, IGF, etc.), energy status (AMP/ATP ratio), oxygen levels, and nutrients (amino acids) Sabatini 2009, 2012). In mammals, the tuberous sclerosis complex 1 and 2 (TSC1-TSC2) serves as a key point of signal integration. The growth factors stimulate TORC1 signaling via PI3K-Akt/ PKB-mediated phosphoinhibition of TSC2 (Inoki et al. 2002;Manning et al. 2002). The energy starvation inhibits TORC1 signaling via AMPK-dependent phosphoactivation of TSC2 (Inoki et al. 2003). Then, TSC2 negatively regulates TORC1 activity by converting GTP-bound Rheb (Ras homolog enriched in brain) into its inactive GDP-bound state (Inoki et al. 2003;Tee et al. 2003). The amino acids, in particular the branched-chain amino acid leucine, positively regulate TORC1. The TORC1 signaling remains sensitive to amino acid deprivation in TSC2 2/2 cells (Nobukuni et al. 2005), indicating that the activation of TORC1 by amino acids is independent of TSC2. Recently, it was demonstrated that TORC1 responds to amino acid availability via mechanisms involving Rag GTPases (Sancak et al. 2008). In the presence of amino acids, the Rag GTPases interact with TORC1, thereby promoting the translocation of TORC1 to the lysosomal membranes and facilitating Rheb's activation of TORC1 (Sancak et al. 2010).In budding yeast Saccharomyces cerevisiae, TOR1 and TOR2 genes were originally identified as the targets of rapamycin, and mutations in TOR1 or TOR2 genes confer resi...

Hypoxic microenvironment deregulates metabolic homeostasis in cancer cells albeit the underlying mechanisms involved in this process remain hitherto enigmatic. 14-3-3ζ/Yes-associated protein (YAP) axis plays a principal role in malignant transformation and tumor development. Here, we report that hypoxia disassembles 14-3-3ζ from YAP and thereby promotes YAP nuclear localization mediated by ERK2, which directly binds to the D-site of mitogen-activated protein kinase (MAPK) docking domain in 14-3-3ζ Leu98/100 and phosphorylates 14-3-3ζ at Ser37. When localizing in nucleus, YAP recruits at pyruvate kinase M2 (PKM2) gene promoter with hypoxia-inducible factor 1α (HIF-1α), for which PKM2 transcription is required. 14-3-3ζ Ser37 phosphorylation is instrumental for the hypoxia-induced glucose uptake, lactate production, and clonogenicity of pancreatic ductal adenocarcinoma (PDAC) cells, as well as tumorigenesis in mice. The 14-3-3ζ Ser37 phosphorylation positively correlates with p-ERK1/2 activity and HIF-1α expression in clinical samples from patients with PDAC and predicts unfavorable prognosis. Our findings underscore an appreciable linkage between YAP transcriptional activation and hypoxic glycolysis governed by ERK2-dependent 14-3-3ζ Ser37 phosphorylation for malignant progression of PDAC.

In this paper, shape memory alloy (SMA) wire actuators are used to control the flap movement of a model airplane wing. Conventionally, the flap of an aircraft wing is driven by electric motors or hydraulic actuators. The use of SMA actuators has the advantage of significant weight reduction. Two SMA actuators are used: one to move the flap up and the other to move the flap down. A sliding mode based nonlinear robust controller is designed and implemented on a real-time data acquisition and control platform to control the position of the flap. Feedback control experiments of both position regulation and tracking control are conducted. To demonstrate the controller's robustness to uncertainties and disturbances, experiments are conducted with additional mass on the flap, changing thermodynamic conditions and time varying aerodynamic loads. Experiments in all cases show that the actual position of the flap closely follows the desired command during experiments. In conclusion, this paper shows the feasibility of using SMA wire actuators for aircraft flap control.

A supramolecular nanoprodrug based on the host–guest complexation of water-soluble pillar[5]arene and a boronate ester linked curcumin was constructed, which could selectively release drug in hepatoma cells by dual-responsiveness of pH and GSH.