Bubble Flow Analysis of High Speed Cylindrical Roller Bearing under Fluid-Solid Thermal Coupling

Heat generation model of high speed cylindrical roller bearing is constructed by calculating the local friction in the bearing. Bubble flow calculation model of roller bearing considering fluid-solid thermal coupling is constructed based on two-body fluid model and k-ε turbulent model, in which diameter and size of bubbles, breakup, and coalescence model of bubbles are considered. Using dynamic mesh method, a new method for evaluating bearing temperature is set up treating the rolling elements as moving heat sources. Based on these models and finite element method, bubble flow of a high speed roller bearing is studied based on FLUENT software. The numerical study reveals the relationship between velocity of bearing, air volume fraction, and velocity and pressure of oil-air flow. An increase of air content in the oil produces a lower pressure at the bearing outlet while the exit fluid velocity increases. When fluid-solid thermal coupling effect is considered, velocity and pressure at outlet of the bearing both become larger, while temperature of bearing is lower than that without coupling. In comparison, the coupling effects on flow pressure and temperature are obvious. For a given rotating speed, there is an optimal value for air volume fraction, such that temperature rise of the bearing reaches the lowest value. Experiments verify the outcomes of the method presented in this paper

Compromised ATP binding as a mechanism of phosphoinositide modulation of ATP-sensitive K+ channels

AbstractInhibition of ATP-sensitive K+ (KATP) channels by ATP, a process presumably initiated by binding of ATP to the pore-forming subunit, Kir6.2, is reduced in the presence of phosphoinositides (PPIs). Previous studies led to the hypothesis that PPIs compromise ATP binding. Here, this hypothesis was tested using purified Kir6.2. We show that PPIs bind purified Kir6.2 in an isomer-specific manner, that biotinylated ATP analogs photoaffinity label purified Kir6.2, and that this labeling is weakened in the presence of PPIs. Patch-clamp measurements confirmed that these ATP analogs inhibited Kir6.2 channels, and that PPIs decreased the level of inhibition. These results indicate that interaction of PPIs with Kir6.2 impedes ATP-binding activity. The PPI regulation of ATP binding revealed in this study provides a putative molecular mechanism that is potentially pivotal to the nucleotide sensitivity of KATP channels

Robust Sliding Mode Control for Stochastic Uncertain Discrete Systems with Two-Channel Packet Dropouts and Time-Varying Delays

In this paper, the control problem is investigated for discrete time-varying delayed systems with stochastic uncertainty, external disturbance, and two-channel packet dropouts. Sliding mode functions with packet loss probabilities are proposed for the packet loss problem in the sensor–controller channel and the controller–actuator channel. Furthermore, by employing the Lyapunov–Krasovskii functional, some new stability conditions are established in terms of solvable linear matrix inequalities (LMIs), and H∞ performance is analyzed for the sliding mode motion of the system. Meanwhile, a sliding mode controller is designed to drive the system state to the pre-designed sliding surface. Moreover, the designed controller can be robust for two-channel packet dropouts, time-varying delays, stochastic uncertainty and external disturbance. Finally, two numerical examples are given to demonstrate the feasibility of the proposed theoretical method

High-pressure structural and electronic properties of InN

We theoretically study the electronic properties, and,pressure-induced solid-solid phase transformation by InN by using the first-principles pseudopotential method. The wurtzite (B4), rocksalt (B1), zinc-blende (B3), CsCl-type (B2), and Cmcm crystal structures of InN have been considered. The calculations indicate that the phase transitions from B4 phase to B1 phase and B3 structure to B1 structure occur at a transition pressure of 10.2 and 9.6 GPa, respectively. The detailed volume changes during the phase transformations were analyzed. Moreover, the analysis of the band structure indicates that the bandgap of B4 phase is direct, while B1 phase is indirect under high-pressure. The mechanism of these changes of band structures was analyzed. The positive pressure derivative of the indirect and direct gap indicates that it is impossible to make B1 phase of InN metallic up to 200 GPa. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Differential Evolution for Lifetime Maximization of Heterogeneous Wireless Sensor Networks

Maximizing the lifetime of wireless sensor networks (WSNs) is a hot and significant issue. However, using differential evolution (DE) to research this problem has not appeared so far. This paper proposes a DE-based approach that can maximize the lifetime of WSN through finding the largest number of disjoint sets of sensors, with every set being able to completely cover the target. Different from other methods in the literature, firstly we introduce a common method to generate test data set and then propose an algorithm using differential evolution to solve disjoint set covers (DEDSC) problems. The proposed algorithm includes a recombining operation, which performs after initialization and guarantees at least one critical target’s sensor is divided into different disjoint sets. Moreover, the fitness computation in DEDSC contains both the number of complete cover subsets and the coverage percent of incomplete cover subsets. Applications for sensing a number of target points, named point-coverage, have been used for evaluating the effectiveness of algorithm. Results show that the proposed algorithm DEDSC is promising and simple; its performance outperforms or is similar to other existing excellent approaches in both optimization speed and solution quality

Structural stability and optical properties of AlN explored by ab initio calculations

Pressure-induced structural phase transformations, electronic and optical properties of AlN are investigated by first-principles method based on the plane-wave basis set. The wurtzite (B4), zincblende (B3), rocksalt (B1), b-beta- Sn, NiAs, anti-NiAs, cinnabar, and simple cubic with 16-atom basis (SC16) phases of AlN have been considered. The calculations demonstrate that there exists a phase transition from B4 structure to B1 phase at the transition pressure of 12.7 GPa. Analysis of band structures suggests that the B4-AlN has a direct gap of 4.13 eV, while B1 phase become indirect under high pressure. The mechanism of these changes of band structures is analyzed. The positive pressure derivative of band gap energies for B1 phase might be due to the absence of d occupations in the valence bands. In addition, the imaginary parts of dielectric function for the polarization in the xy plane and average of the imaginary parts of dielectric function over three Cartesian directions were calculated. The origin of the spectral peaks was interpreted based on the electronic structure. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved

Aberrant methylation and downregulation of ZNF667-AS1 and ZNF667 promote the malignant progression of laryngeal squamous cell carcinoma

Abstract Background Dysregulated long noncoding RNAs (lncRNAs) are involved in the development of tumor. Aberrant methylation is one of the most frequent epigenetic alterations that regulate the expression of genes. The aim of this study was to determine the expression and methylation status of ZNF667-AS1 and ZNF667, elucidate their biological function in the development of LSCC, and identify a cis-regulation of ZNF667-AS1 to ZNF667. Methods The expression and methylation status of ZNF667-AS1 and ZNF667 in laryngeal cancer cell lines and LSCC samples were tested respectively. The function of two laryngeal cancer cell lines with overexpression of ZNF667-AS1 or ZNF667 was detected. The regulation between ZNF667-AS1 and ZNF667 was determined. Results Significant downregulation of ZNF667-AS1 was detected in laryngeal cancer cell lines and LSCC tumor tissues. The reduced expression of ZNF667-AS1 was associated with moderate/poor pathological differentiation of LSCC tumor tissues. Aberrant hypermethylation of the CpG sites of ZNF667-AS1, closing to the transcriptional start site (TSS), was more critical for gene silencing, and associated with moderate/poor pathological differentiation. In vitro hypermethylation of promoter region closing to TSS of ZNF667-AS1 decreased the luciferase reporter activity. Overexpression of ZNF667-AS1 reduced the proliferation, migration, and invasion ability of AMC-HN-8 and TU177 cells. The sense strand, ZNF667, was positively correlated with ZNF667-AS1 in expression and function. Overexpression of ZNF667-AS1 led to increased expression of ZNF667 in mRNA and protein level. ZNF667-AS1 and ZNF667 may be associated with epithelial-mesenchymal transition (EMT) process. Conclusions ZNF667-AS1 and ZNF667 are both down-regulated by hypermethylation, and they serve as tumor suppressor genes in LSCC. ZNF667-AS1 regulates the expression of ZNF667 in cis

Non-alcoholic fatty liver disease is an influencing factor for the association of SHBG with metabolic syndrome in diabetes patients

Abstract Metabolic syndrome (MS) and non-alcoholic fatty liver disease (NAFLD) have been identified as risk factors affecting serum sex hormone binding globulin (SHBG) levels. We conducted this cross-sectional study to delineate whether MS or NAFLD has more impact on circulating SHBG levels in type 2 diabetes (T2D) patients. Anthropometric and biochemical parameters including serums SHBG, testosterone (TT), liver enzymes, lipids, insulin, C-peptide and plasma glucose were measured. Regardless of the MS status, SHBG level was significantly lower in NAFLD patients than in non-NAFLD patients (P < 0.001). In the multiple linear regression analysis, lower serum SHBG level was strongly correlated with a higher incidence of NAFLD, but not MS components. In logistic regression analyses, after adjusted for age, sex, duration of diabetes, smoking status, and alcohol use, the ORs and 95%CI for presence of MS was 2.26 (95%CI 1.91–2.68) and for presence of NAFLD was 6.36 (95%CI 4.87–8.31) with per one SD decrease in serum SHBG (both P < 0.001). In conclusion, lower serum SHBG is associated with a higher prevalence of NAFLD, compared with MS and other metabolic disorders, in T2D patients. NAFLD might be an important influencing factor for the association of circulating SHBG with MS in T2D patients