Synergic effect within n-type inorganic–p-type organic nano-hybrids in gas sensors

This paper describes the exploration of a synergic effect within n-type inorganic–p-type organic nanohybrids in gas sensors. One-dimensional (1D) n-type SnO2–p-type PPy composite nanofibers were prepared by combining the electrospinning and polymerization techniques, and taken as models to explore the synergic effect during the sensing measurement. Outstanding sensing performances, such as large responses and low detection limits (20 ppb for ammonia) were obtained. A plausible mechanism for the synergic effect was established by introducing p–n junction theory to the systems. Moreover, interfacial metal (Ag) nanoparticles were introduced into the n-type SnO2–p-type PPy nano-hybrids to further supplement and verify our theory. The generality of this mechanism was further verified using TiO2–PPy and TiO2–Au–PPy nano-hybrids. We believe that our results can construct a powerful platform to better understand the relationship between the microstructures and their gas sensing performances

Serum Amyloid a Promotes Visfatin Expression in Macrophages

Visfatin has been reported to exert an important role in the development of atherosclerosis. However, the mechanism that regulated the expression of Visfatin has not been elucidated yet. This study aimed to investigate the effect of SAA on the regulation of Visfatin, as well as the potential pathway. After RAW264.7 macrophages and primary monocytes were stimulated with SAA, the mRNA and protein expression of Visfatin was detected with real-time PCR and western blot, respectively. The concentration of Visfatin in the supernatant was measured with ELISA. Formyl peptide receptor 2 (FPR2) agonist (WKYMVm) and inhibitor (WRW4), extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor (PD98059), and peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist (Rosiglitazone) and inhibitor (GW9662) were used to investigate the mechanism of regulation of Visfatin. The results demonstrated that SAA upregulated Visfatin expression in cultured RAW264.7 macrophages and in the primary monocytes. WRW4 decreased SAA-induced Visfatin production, while WKYMVm could induce Visfatin expression. PD98059 reduced SAA-induced Visfatin production. What is more, GW9662 inhibited SAA-induced Visfatin production, while Rosiglitazone promoted Visfatin expression. These results demonstrate that SAA upregulates Visfatin expression via a FPR2/ERK1/2/PPAR-γ signaling pathway

Serum Amyloid A Induces a Vascular Smooth Muscle Cell Phenotype Switch through the p38 MAPK Signaling Pathway

Atherosclerosis is an important pathological condition which is accompanied by a vascular smooth muscle cell (VSMC) phenotype switch toward a synthetic phenotype. As an acute-phase protein, Serum Amyloid A (SAA) is thought to have a close relationship to atherosclerosis development. However, no study has investigated the direct effect of SAA on the VSMC phenotype switch, as well as the underlying mechanisms. The purpose of our study was to explore the effect of SAA on the VSMC phenotype switch and the potential mechanisms involved. In our study, we found that SAA induced the VSMC phenotype switch which reduced expression of the smooth muscle cell (SMC) marker and enhanced expression of the matrix synthesis related marker. The proliferative ability of VSMCs was also increased by SAA treatment. Furthermore, our research found that SAA activated the ERK1/2 and p38 MAPK signaling pathways. Finally, by applying the ERK1/2 and p38 inhibitors, U0126 and SB203580, we demonstrated that the SAA-induced VSMC phenotype switch was p38-dependent. Taken together, these results indicated that SAA may play an important role in promoting the VSMC phenotype switch through the p38 MAPK signaling pathway

Femtosecond laser-induced nonlinear absorption in thick polystyrene

The nonlinear absorption behavior of thick polystyrene sample was experimentally investigated and theoretically analyzed. As polystyrene is transparent to the applied laser wavelength, the absorption was mainly through nonlinear absorption by the bulk material. The effective second order nonlinear absorption coefficient (β) was determined with the z scan technique. The nonlinear behavior at different laser powers: 5.2 mW, 10.4 mW, 14.4 mW and 23.5 mW were investigated. The transmittance of laser energy was measured and a significant change was observed with different sample distance from the laser focal plane. By treating the thick polystyrene sample as a stack of thin layers, the effective nonlinear absorption coefficient was determined to be 0.000695 m/W with a standard deviation of 0.000026.Accepted versio

Surface Wettability Modification of Cyclic Olefin Polymer by Direct Femtosecond Laser Irradiation

The effect of laser irradiation on surface wettability of cyclic olefin polymer (COP) was investigated. Under different laser parameters, a superhydrophilic or a superhydrophobic COP surface with a water contact angle (WCA) of almost 0° or 163°, respectively, could be achieved by direct femtosecond laser irradiation. The laser power deposition rate (PDR) was found to be a key factor on the wettability of the laser-treated COP surface. The surface roughness and surface chemistry of the laser-irradiated samples were characterized by surface profilometer and X-ray photoelectron spectroscopy, respectively; they were found to be responsible for the changes of the laser-induced surface wettability. The mechanisms involved in the laser surface wettability modification process were discussed.Published versio

Study on current characteristic detection method of hydraulic solenoid valve in nuclear power plant

In this paper, a set of electromagnetic valve current characteristic test system is designed to improve the reliability of the trip solenoid valve in the field steam turbine system of nuclear power plant. The test system starts from the field requirements, working principle of solenoid valve, software control and other aspects to complete the pressure suppression function of the hydraulic test system and the functions of data acquisition, storage, display, playback and so on. The test system is composed of a hydraulic system and an electrical control system. The system verifies the reliability of the tested object by detecting the important parameters of the solenoid valve, calibrating the current characteristic points, calculating the characteristic parameters, and judging whether the test is qualified. The test results show that the system has been successfully applied in nuclear power field, meets the needs of the site, and works well

DISCHARGE CHARACTERISTICS OF Ti AND FILM PREPARATION USING HYBRID HIGH POWER IMPULSE MAGNETRON SPUTTERING

Hybrid high power impulse magnetron sputtering (HIPIMS) is a new-generation HIPIMS technique with a pulse and dirrect current power supply parallelled connection operation. In this work, the influence of dirrect current from 0 to 4.0 A supplied by the dirrect current power is investigated on hybrid HIPIMS Ti discharge characteristics, plasma parameters (plasma potential, electron temperature and electron density) and Ti film properties in an Ar atmosphere. The results show that target voltage and current are characterized by a peak with variation of time in different dirrect currents. Although the target voltage is barely affected, the target current decreases with increasing the dirrect current during the pulse turn-on stage. The plasma parameters determined by a Langmuir probe have been significantly influenced by the dirrect current. Moreover, the deposition rate and average roughness increase while the hardness and elastic modulus have a slight decrease with the variation of dirrect current from 1.0 to 3.0 A. The samples are selected for comparison with that prepared by conventional direct current magnetron sputtering (DCMS) at the same average target power 650 and 1500 W. The results demonstrate that Ti films using hybrid HIPIMS have a close deposition rate and a superior quality and performance to those prepared using DCMS especially at the low target power 650 W when the direct current is 1.0 A

Thermal effect of femtosecond laser polystyrene processing

The thermal effects during femtosecond laser polymer processing have been investigated. The temperature increase during the process was directly observed by employing an infrared camera. Our results showed that the temperature can increase significantly during the laser-material interaction process. This indicates that a large percentage of laser energy can be converted to heat energy and dissipated into the bulk material. The temperature change as a function of the laser intensity was investigated. Nonlinear absorption was observed and proved to be the major absorption mechanism during the femtosecond laser polymer interaction process. The simulated results of thermal effect with a 3D FE model were compared with the experimentally measured temperature profile. The mechanism involved in the laser beam-material interaction was discussed.Agency for Science, Technology and Research (A*STAR)This work was supported by Singapore Institute of Manufacturing Technology under the Agency for Science, Technology and Research (A*STAR) Singapore