Analysis and control of monolithic piezoelectric nano-actuator

The study of the monolithic piezoelectric actuator, the dominant type of micropositioner is an attractive and challenging area, where realtime control theory and digital signal processing are effectively applied. The actuator can be applied in precision instruments and precision control, such as microscopes, medical and optics instruments because of the piezoelectric ceramic\u27s high resolution, fast transient response, and potential low cost. However, hysteresis nonlinearity and lightly damped vibration exist in the system, which limit the actuator applications. This work focuses on the hysteresis characteristics in time and frequency domains along with experimental and simulated results to verify the effectiveness of the model in describing the hysteresis phenomena. The analytic expressions of the hysteresis harmonics are further applied in hysteresis parameter estimation. A reduced order nonlinear hysteresis observer compensator is proposed, and the stability of the compensated system is discussed. The compensator reduces the hysteresis effect significantly under simulated and experimental conditions. Furthermore, an adaptive hysteresis observer compensator is further presented to compensate the slowly changed hysteresis parameters. Time division multi-control strategy is proposed to implement fast transient response, low vibration and high resolution. Extensive numerical simulation and real-time experiment are carried out to verify the control strategies. GUI is developed to implement the communication between the code in DSP memory and Labview, which improves the efficiency in system test

Influence of Polygonal Wear on Dynamic Performance of Wheels on High-Speed Trains

With increases in train speed and traffic density, polygonal wear of railway wheels arises accordingly, induced by the high impacts between wheels and rails, which is mainly related to operation safety and ride comfort of vehicle system. This work evaluates the effect of wheel polygon shape on the dynamic performance of the wheel set through numerical simulations. The finite element model, which includes the wheel set and the slab track, was established using ANSYS software to study the effects of polygonal wear on the dynamic behavior of the railway wheel. In the model, wheel–rail interaction forces caused by polygon wheel shape were solved using Universal Mechanisms of wear and were then entered into the finite element model. Using the simulation model, the influence of the harmonic order and out-of-roundness amplitude of wheel polygon on transient dynamic behaviors of the wheels namely, the displacement, acceleration, and von Misses equivalent stress were investigated. The results indicate that both the maximum dynamic displacement and Von Misses equivalent stress of the wheel plate show proportionality to the OOR amplitude, the harmonic order and the vehicle velocity. Besides, the maximum Von Misses equivalent stress occurs close to the wheel center, whereas the maximum displacement occurs close to the wheel tread. The findings will provide a theoretical basis for on-board detection methods of monitoring wheel polygonal wear

Taraxacum mongolicum extract exhibits antimicrobial activity against respiratory tract bacterial strains in vitro and in neonatal rats by enhancing systemic Th1 immunity

Purpose: To study the antimicrobial activity of the Taraxacum mongolicum extract against respiratory infection-causing bacterial strains in vitro and in neonatal rats.Methods: The in vitro antibacterial activity was assessed by micro-dilution method. Antioxidant activity was determined by ferric reducing antioxidant power (FRAP), nitro blue tetrazolium (NBT) and 2, 2- diphenyl-1-picrylhydrazyl (DPPH) assays. In vivo antimicrobial activity was evaluated in neonatal rat model. Interleukin (IL)-2 (IL-2) and gamma interferon (IFN-γ) were estimated using enzyme-linked immunosorbent assay (ELISA).Results: The hydro-methanol extract of T. mongolicum contained high levels of phenolics and flavonoids, and exhibited strong antimicrobial activity against respiratory infection-causing bacterial species with MICs of 25 - 100 μg/ml, and MBCs of 55 - 215 μg/ml. The highest and lowest antimicrobial activities were observed against Streptococcus pneumonia and Haemophilus influenza, respectively. The extract at doses of 25 and 50 mg/kg exerted protective effects against Streptococcus pneumonia infected neonatal rats by boosting their Th1 immunity. It enhanced the production of interleukin (IL)-2, concomitant with decreased production of interferon (IFN)-γ in neonatal rats. The extract contained isoetin, hesperidin, naringenin, kaempferol, sinapinic and gallic acid.Conclusion: These results suggest that the hydro-methanolic extract of Taraxacum mongolicum and its constituents can be potentially developed for use in the management of respiratory bacterial infections.Keywords: Respiratory tract infection, Interleukin, Taraxacum mongolicum, Immunity, Neonatal rat

Microwave-induced acoustic imaging of biological tissues

We present tomographic imaging of biological tissues by use of microwave-induced acoustic signal. It was demonstrated that the acoustic signal was proportional to the intensity of the incident microwave and was related to the absorption property of microwave in the medium. Pulsed microwave radiation was used to illuminate the samples. Absorbed microwave energy caused thermoelastic expansion that radiated acoustic waves. A focused ultrasonic transducer detected the time-resolved acoustic signals. Each acoustic signal was converted into a one-dimensional image. A linear scanning of the ultrasonic transducer yielded multiple one-dimensional images, which formed a two-dimensional image. The imaging contrast is based on the difference in the dielectric constants among biological tissues. Because of the large contrast in microwave absorption among different tissue types, microwave-induced acoustic tomography could potentially provide a new modality for detecting early-stage cancers

Partial Removal of Phenolics Coupled with Alkaline pH Shift Improves Canola Protein Interfacial Properties and Emulsion in In Vitro Digestibility

The effect of polyphenol removal (“dephenol”) combined with an alkaline pH shift treatment on the O/W interfacial and emulsifying properties of canola seed protein isolate (CPI) was investigated. Canola seed flour was subjected to solvent extraction to remove phenolic compounds, from which prepared CPI was exposed to a pH12 shift to modify the protein structure. Dephenoled CPI had a light color when compared with an intense dark color for the control CPI. Up to 53% of phenolics were removed from the CPI after the extraction with 70% ethanol. Dephenoled CPI showed a partially unfolded structure and increased surface hydrophobicity and solubility. The particle size increased slightly, indicating that soluble protein aggregates formed after the phenol removal. The pH12 shift induced further unfolding and decreased protein particle size. Dephenoled CPI had a reduced β subunit content but an enrichment of disulfide-linked oligopeptides. Dephenol improved the interfacial rheology and emulsifying properties of CPI. Although phenol removal did not promote peptic digestion and lipolysis, it facilitated tryptic disruption of the emulsion particles due to enhanced proteolysis. In summary, dephenol accentuated the effect of the pH shift to improve the overall emulsifying properties of CPI and emulsion in in vitro digestion

An optical clock based on a topological attractor in the polariton superfluid dynamics

We propose an optical polariton clock based on the topologically protected persistent oscillatory dynamics of a polariton superfluid, which is excited non-resonantly by a super-Gaussian laser beam in a semiconductor microcavity containing an external C-shape potential. The persistent oscillations, characterised by a topological attractor, are based on the dynamical behavior of small Josephson vortices rotating around the edge of the core of the central vortex. The clock demonstrates a remarkable stability towards perturbations and may be tuned by the pump laser intensity to two different frequency ranges: 20.16{\pm}0.14 GHz and 48.4{\pm}1.2 GHz. This clock generator is bistable due to the chirality of the vortex

Expression and Clinical Significance of SHP2 in the Tumor Tissues of Smokers with Lung Cancer

Background and objective It has been proved that protein phosphorylation and dephosphorylation were important mechanisms in lung cancer development, and tobacco smoking is an important risk factor of lung cancer. The aim of this study is to investigate the expression and clinical significance of protein tyrosine phosphatase SHP2 in non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC); the relationship between tobacco smoking and the expression of SHP2 is also studied. Methods Immunohistochemistry (Invision) and fluorescence in situ hybridization (FISH) were used to detect the expression of SHP2 and the augment of SHP2 mRNA in the 53 lung cancer specimens. Results The weak positive rate of SHP2 was 80% (which was also the total positive rate) in normal bronchial epithelium. The weak, moderate and strong positive rates were 35.4%, 43.8% and 6.2% (total positive rate was 85.4%) in 48 NSCLC patients, 0%, 80% and 20% (total positve rate was 100%) in 5 SCLC patients, 40.7%, 37.4% and 3.7% (total positive rate was 81.5%) in the tumor tissues of 27 NSCLC patients who didn’t smoke and 23.8%, 71.4% and 4.7% (total positive rate was 100%) in the tumor tissues of 21 NSCLC patients whose smoking indexes were ≥400. Significant differences of SHP2 expression were observed between tumor tissues and normal bronchial epithelium, NSCLC and SCLC, and between different smoking indexes (P < 0.05). Conclusion The enhancement of SHP2 expression in the tumor tissues of NSCLC patients who smoke may be correlated with tobacco smoking; SHP2 may play certain role in the development of lung cancer; SHP2 prospectively provides new ideas for the drug research and development of lung cancer treatment

Fabrication of Cubic p-n Heterojunction-Like NiO/In 2

Oxide semiconductor In2O3 has been extensively used as a gas sensing material for the detection of various toxic gases. However, the pure In2O3 sensor is always suffering from its low sensitivity. In the present study, a dramatic enhancement of sensing characteristic of cubic In2O3 was achieved by deliberately fabricating p-n heterojunction-like NiO/In2O3 composite microparticles as sensor material. The NiO-decorated In2O3 p-n heterojunction-like sensors were prepared through the hydrothermal transformation method. The as-synthesized products were characterized using SEM-EDS, XRD, and FT-IR, and their gas sensing characteristics were investigated by detecting the gas response. The experimental results showed that the response of the NiO/In2O3 sensors to 600 ppm methanal was 85.5 at 260°C, revealing a dramatic enhancement over the pure In2O3 cubes (21.1 at 260°C). Further, a selective detection of methanol with inappreciable cross-response to other gases, like formaldehyde, benzene, methylbenzene, trichloromethane, ethanol, and ammonia, was achieved. The cause for the enhanced gas response was discussed in detailed. In view of the facile method of fabrication of such composite sensors and the superior gas response performance of samples, the cubic p-n heterojunction-like NiO/In2O3 sensors present to be a promising and viable strategy for the detection of indoor air pollution