Analysis and Design of the Reconfiguration Motion Qualities of a Deformable Robot Based on a Metamorphic Mechanism

Traditional wheel-legged ground mobile robots can only partially deform during wheel-leg switching, resulting in failure to achieve better environmental adaptability. Metamorphic mechanisms can be introduced into car structure designs. A new type of wheel-legged ground mobile robot, namely a deformable robot, is proposed in this study. Compared with traditional wheel-legged ground mobile robots, the deformable robot is capable of global reconfiguration, that is, when transitioning between the wheeled type (vehicle state) and the legged type (humanoid state), the shape, structure, degrees of freedom, and position of the centre of mass will change significantly. First, based on the characteristics of the wheel-legged compound motion, a structural model of the deformable robot was proposed and designed, and its reconfiguration motion was planned. Then, a kinematic model of the coupled reconfiguration process of the deformable robot was established. A horizontal lifting model was created to keep the front body level when lifting. The motion law of each active joint angle over time was designed based on the requirements of the reconfiguration motion smoothness. The criterion of reconfiguration stability was established and measures to improve it were proposed. Finally, based on the simulation verification of the smoothness, horizontality, and stability of the coupled reconfiguration of the system, a prototype of the deformable robot was developed, and a coupled reconfiguration experiment was conducted on an actual road surface. The experiment results show that the reconfiguration motion of the deformable robot between the vehicle state and the humanoid state had good motion qualities

Deubiquitinase USP47/UBP64E Regulates β-Catenin Ubiquitination and Degradation and Plays a Positive Role in Wnt Signaling

Wnt signaling plays important roles in development and tumorigenesis. A central question about the Wnt pathway is the regulation of β-catenin. Phosphorylation of β-catenin by CK1α and GSK3 promotes β-catenin binding to β-TrCP, leading to β-catenin degradation through the proteasome. The phosphorylation and ubiquitination of β-catenin have been well characterized; however, it is unknown whether and how a deubiquitinase is involved. In this study, by screening RNA interference (RNAi) libraries, we identified USP47 as a deubiquitinase that prevents β-catenin ubiquitination. Inactivation of USP47 by RNAi increased β-catenin ubiquitination, attenuated Wnt signaling, and repressed cancer cell growth. Furthermore, USP47 deubiquitinates itself, whereas β-TrCP promotes USP47 ubiquitination through interaction with an atypical motif in USP47. Finally, in vivo studies in the Drosophila wing suggest that UBP64E, the USP47 counterpart in Drosophila, is required for Armadillo stabilization and plays a positive role in regulating Wnt target gene expression

Kruppel-Like Factor 4-Dependent Staufen1-Mediated mRNA Decay Regulates Cortical Neurogenesis

Kruppel-like factor 4 (Klf4) is a zinc-finger-containing protein that plays a critical role in diverse cellular physiology. While most of these functions attribute to its role as a transcription factor, it is postulated that Klf4 may play a role other than transcriptional regulation. Here we demonstrate that Klf4 loss in neural progenitor cells (NPCs) leads to increased neurogenesis and reduced self-renewal in mice. In addition, Klf4 interacts with RNA-binding protein Staufen1 (Stau1) and RNA helicase Ddx5/17. They function together as a complex to maintain NPC self-renewal. We report that Klf4 promotes Stau1 recruitment to the 3′-untranslated region of neurogenesis-associated mRNAs, increasing Stau1-mediated mRNA decay (SMD) of these transcripts. Stau1 depletion abrogated SMD of target mRNAs and rescued neurogenesis defects in Klf4-overexpressing NPCs. Furthermore, Ddx5/17 knockdown significantly blocked Klf4-mediated mRNA degradation. Our results highlight a novel molecular mechanism underlying stability of neurogenesis-associated mRNAs controlled by the Klf4/Ddx5/17/Stau1 axis during mammalian corticogenesis

Studying the interface between croconic acid thin films and substrates using a slow positron beam

Croconic acid (CA) is the first organic ferroelectric with a spontaneous polarity in bulk samples comparable to its inorganic counterparts. As a natural extension of study, ultrathin CA films (∼nm scale) were investigated to reveal ferroelectric effects in films on different substrates for their fundamental and industrial significance. However, the void defect at the interface between the film and substrate is presumed to interfere with surface effects. In this work, a non-invasive technique, a slow positron beam, coupled with Doppler broadening energy spectroscopy (DBES), is applied to study the void defects within the interfacial layer between CA films and Si and SiO2 substrates. The effect of external electric field on defect formation is also investigated and an underlying mechanism is proposed

The Effect of Governance Quality on Economic Growth: Based on China’s Provincial Panel Data

This paper investigates the impact of governance quality on economic growth in China. After developing a theoretical framework for the effect of governance quality on local economic growth, this article studies the panel data in provincial regions over the period 2001–2015 by constructing a new comprehensive index of provincial governance, and checks the robustness of the empirical findings from four aspects. The results show that governance quality has a positive effect on economic growth, due to good governance strengthening the “helping hand” or weakening the “grabbing hand” of power. Governance quality presents diminishing marginal returns, which means that the high-speed economic growth effect becomes less and less, while the high-quality economic development effect becomes more and more. Higher governance quality could bring a high-speed economic growth effect in the western region, while higher governance quality could bring a high-quality economic development effect in the eastern region. Compared with fixed-asset investment, human capital has played a more important role in economic growth. In order to promote the sustainable development of China’s economy, policy makers should improve local governance quality, strengthen the capacity of independent innovation, and promote the accumulation of high-quality human capital

Multi-parameter quantitative assessment of 3D geological models for complex fault-block oil reservoirs

In the field of 3D geologic modeling, researchers often pay more attention to modeling methods and workflows, but neglect the quantitative evaluation of models. If the evaluation is narrowed to the same reservoir type, the comparability and practicality of quantitative assessment will be emerging. The evaluation system should include three parts: data verification, geological understanding and process check. Data verification mainly involves testing the accuracy of local prediction with actual data, and geological understanding is to examine whether the global estimation honors geological principles and prior insights. Process check is also indispensable to avoid occasionality. To this end, we produced a set of assessment criteria, taking complex fault-block sandstone oil reservoir as an example. To be specific, thirteen characteristic parameters were totally selected, setting weights according to their rated importance, formulating three-level evaluation standards in a centesimal system for each characteristic parameter, and obtaining the final assessment based on the cumulative score. The results indicate that such evaluation can not only access the quality of the model objectively and comprehensively, but also identify the aspects in need of improvement through the deduction items. Key words: reservoir characterization, geological modeling, quality evaluation, characteristic parameter, reserves estimation, fault-block oil reservoi

Impact of coal evolution on formation of tight sandstone reservoirs: A case study in the Daniudi gas field, Ordos Basin, China

Tight sandstone gas in coal-bearing strata has become an important unconventional gas worldwide. This research aims at understanding the impacts of coal evolution on diagenesis and reservoir quality of sandstones by means of thin section, cathode luminescence (CL), scanning electron microscope (SEM), stable isotope analysis, and fluid inclusions. The results show that carbonate cement was the main type of cement developed in tight sandstone reservoirs, of which the carbonate ions were jointly provided by coal layers and reaction in adjacent mudstones. For sandstones close to coal layers, their carbonate ions were mainly controlled by coal evolution and there was various carbonate cement developed due to cations supplied by seawater and the intense dissolution of volcanic fragments and feldspars. Combined with coal thermal simulation and burial history, it implies that at different maturity stages of coal evolution, its impact on sandstone diagenesis was different. In the early stage, the main product was CO 2 , which caused the dissolution of early calcite and promoted intense compaction. In the mature stage, CO 2 and other hydrocarbon gases were released, resulting in more dissolution and silica cementation. In the over-mature stage, the main product was methane, and CO 2 that did not spill out preserved by forming carbonate cement. The coal evolution had a strong impact on the reservoir quality of sandstone with large grain sizes, but little effect on medium- and fine-grained sandstones. High porosity and low permeability reservoirs were usually formed in small conglomerates and coarse-grained sandstones away from coal layers. While low porosity and high permeability reservoirs were distributed close to coal layers. This study aids in understanding the formation mechanism of tight sandstone reservoirs in coal measures and provides theoretic support for further exploration

Effects of Electroacupuncture on Ovarian Expression of the Androgen Receptor and Connexin 43 in Rats with Letrozole-Induced Polycystic Ovaries

Background. Polycystic ovarian syndrome (PCOS) occurs in women of reproductive age and is often characterized by reproductive and endocrine dysfunction. Androgens play a major role in PCOS, and previous studies reported abnormal expression of Connexin 43 (Cx43) in animal models of PCOS, suggesting an association of Cx43 with PCOS pathogenesis. Experimental and clinical evidence indicated that acupuncture may be a safe and effective approach for treating reproductive and endocrine disorders in women with PCOS. This study aimed to determine the effects of electroacupuncture (EA) on PCOS and its relationship with the expression of the androgen receptor (AR) and Cx43. Methods. In total, 30 female Sprague Dawley rats (6 weeks old) were randomly divided into three groups: control group, letrozole (LE) group, and LE + EA group. Rats were administered LE solution (1.0 mg/kg) for 21 consecutive days to induce PCOS. For the LE + EA group, additional EA treatment was conducted (2 Hz, 20 min/d) with “Guanyuan” (CV3) for 14 consecutive days. After hematoxylin-eosin staining, the ovarian structure was observed with an optical microscope, and serum levels of the following hormones were examined via enzyme-linked immunosorbent assay (ELISA): testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH); luteinizing hormone (LH), insulin (INS), anti-Müllerian hormone (AMH), and inhibin B (INHB). Fasting blood glucose (FBG) levels were evaluated using glucose oxidase-peroxidase. Ovarian mRNA and protein expressions of AR and Cx43 were determined by real-time RT-PCR and Western blot analysis. Results. EA was found to restore the cyclicity and ovarian morphology in the PCOS rat model. Serum derived from the LE + EA group showed significant decreases in the levels of T, free androgen index (FAI), LH, LH/FSH ratio, AMH, INHB, and fasting serum insulin (FINS), and significant increases in the levels of E2, FSH, and SHBG. Western blot analysis showed a decreased protein expression of ovarian AR and Cx43; real-time RT-PCR showed reduced expression of ovarian mRNA levels of AR and Cx43. Conclusions. In conclusion, our results showed that EA can ease hyperandrogenism and polycystic ovary morphology in PCOS rats. Furthermore, EA counteracted the letrozole-induced upregulation of AR and Cx43. These results suggested that acupuncture can break the vicious cycle initiated by excessive androgen secretion and may be an effective treatment method for improving the reproductive and endocrine dysfunction caused by PCOS

Dexamethasone promotes the endoplasmic reticulum stress response of bone marrow mesenchymal stem cells by activating the PERK‐Nrf2 signaling pathway

Abstract The pathogenesis of steroid‐induced avascular necrosis of femoral head (SANFH) is complex, and there is a lack of effective early prevention method. The aim of the present study was to evaluate the effect of dexamethasone (DEX) on the biological behavior of bone marrow mesenchymal stem cells (BMSCs) and to explore the possibility of DEX in the clinical treatment of SANFH. The effect of DEX on the proliferation of BMSCs was evaluated by Counting Kit‐8 assay, western blot assay, and enzyme‐linked immunosorbent assay. Flow cytometry and western blot assay were performed to detect the effect of DEX on the apoptosis of BMSCs. Quantitative real‐time PCR and western blot assay were performed to detect the effect of DEX on the expression of endoplasmic reticulum stress (ERS)‐related genes. Immunoblotting analysis was conducted for detecting the nuclear‐cytoplasmic distribution of Nrf2. DEX could significantly inhibit the proliferation of BMSCs and promote apoptosis of BMSCs. DEX could increase the expression of PERK, ATF6, and IRE1a, and induce nuclear translocation of Nrf2. The addition of ML385 could reverse the effect of DEX on BMSCs. DEX could activate the PERK‐Nrf2 pathway to promote ERS and finally affect the cell proliferation and apoptosis of BMSCs