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Abstract: An ultrasensitive two-dimensional photonic crystal biosensor is theoretically demonstrated in this paper. Such device consists of a waveguide and high Q-value microcavities which are realized by introducing line and point defects into the photonic crystal respectively. The band structures and the transmission spectra are obtained from the Finite-Difference –Time-Domain (FDTD) method. The simulation results showed that such device is strongly sensitive to the refractive index of the analyte injected into the point defect. The designed device can be applied for measurements of the refractive index and detection of protein-concentrations. [Copyright &y& Elsevier]

• The failure process mainly includes the erosion damage of the original passive film and the subsequent peeling of the surface material. • Carbon deposit on the crown of piston react with the surface of the aluminum matrix to form brittle phase (Al 4 C 3 and Al 2 O 3). • The residual piston hardness in the cross section of the damage zone decreases significantly as the ablation level increases. The failure mechanisms of Al-Si-Cu alloy in piston of diesel engine due to abnormal combustion are not fully understood at present. In this paper, the bench test of the original piston was carried out, which induced knock combustion by monitoring of the pressure signal in the cylinder. The results show that the failure process mainly includes the erosion damage of the original passive film and the subsequent peeling of the surface material which was proved by XRD, optical and scanning electron microscopy, 3D confocal laser scanning microscope and other research methods. During erosion damage, carbon deposit on the crown of piston react with the surface of the aluminum matrix to form brittle phase (Al 4 C 3 and Al 2 O 3). In addition, the residual hardness in the cross section of the damage zone decreases significantly as the ablation level increases. [ABSTRACT FROM AUTHOR]

• A novel and compact temperature and relative humidity sensor was proposed and implemented. • The sensor was based on compact Mach-Zehnder interferometer and Fabry-Perot interferometer. • Detection of temperature and RH can be achieved by monitoring the spectrums of FPI and MZI. • The sensitivity to RH is −0.132 nm/%RH with resolution of 0.15 %RH. • The sensitivity to temperature is 0.37 nm/°C with the resolution of 0.05 °C. A novel and compact temperature and relative humidity (RH) simultaneously measurement sensor based on compact Mach-Zehnder interferometer (MZI) and Fabry-Perot interferometer (FPI) is proposed and experimental implemented. The sensing structure is made by splicing a 200 μm single mode fiber (SMF) between two 10 cm SMFs with large core-offset. The core-offset distance is 62.8 μm coated with RH sensitive material graphene quantum dots and polyvinyl alcohol (GQDs-PVA). The transmitted structure acts as MZI, and the reflected structure acts as FPI, then the simultaneous detection of temperature and RH can be achieved by monitoring the spectrums of FPI and MZI, respectively. The sensitivity to RH is −0.132 nm/%RH with resolution of 0.15 %RH, and the sensitivity to temperature is 0.37 nm/°C with the resolution of 0.05 °C. The proposed sensor is compact, high sensitivity, simple making and low cost. [ABSTRACT FROM AUTHOR]

• A plasmonic metasurface is proposed to realize PIT effect in a different way. • The generation of PIT effect is benefit from phase coupling. • Transmission can be eliminated by destructive interference of the phase. • A dynamically tunable narrow transmission window can be achieved. A plasmonic metasurface structure consisting of periodically arranged bimolecular units is proposed to realize PIT effect in a way that differ from traditional ways. A high transmission window can be realized by utilizing phase coupling between sub-resonances of the designed bimolecular system. Phase coupling which is benefit from the intense and stable sub-resonances plays an important role in the generation of PIT effect. In the designed metasurface structure, influence of some components on transmission can be eliminated by destructive interference of the phase. The designed metasurfaces can be used in manufacture of optical devices at near infrared region, and general principle has potential applications in terahertz and microwave bands. [ABSTRACT FROM AUTHOR]

The NH 3 sensitivity of a potentiometric YSZ-based planar sensor utilizing ZnFe 2 O 4 sensing electrode (SE) was tuned by sputtering Au on the SE. ZnFe 2 O 4 was prepared by sol-gel method and calcined at 900 °C. ZnFe 2 O 4 -SE was prepared by screen printing and sintered at 1100 °C for 3 h. SEM results show that Au is uniformly distributed in the network structure of the ZnFe 2 O 4 -SE. The response characteristics of the sensor to 5–80 ppm NH 3 were evaluated between 650 °C and 750 °C, and it was found that the response rate and response signal increased significantly after gold sputtering on SE. The performance improvement by gold sputtering may originate from enhanced catalytic activity of the anodic electrode reaction, which was observed by the polarization curve test. At 700 °C, the sensor exhibited the largest sensitivity with the slope of −31.3 mV/decade, and its response to 80 ppm NH 3 was −42.3 mV, and it has relatively short response and recovery time of 25 s and 49 s for 80 ppm NH 3 , respectively. It could even displayed a considerable signal for 5 ppm NH 3 at each temperature. The oxygen concentration had non-negligible influence on the NH 3 response signal. It showed tiny cross sensitivities toward NO x and C 3 H 8 , but weak CO cross sensitivity. When the water vapor concentration is within 10%, the water vapor has a small influence on the response signal. The sensor also displayed slight signal drifts in weekly tests in six weeks, which showed that ZnFe 2 O 4 had a good long-term stability. • ZnFe 2 O 4 was used as NH 3 sensing electrode for potentiometric gas sensor for the first time. • The response signal and response/recovery rate were greatly enhanced after the ZnFe 2 O 4 -SE was tuned by sputtering Au. • The sensor displays a considerable signal for 5 ppm NH 3 between 650 °C and 750 °C. [ABSTRACT FROM AUTHOR]

• The NH 3 sensing properties are affected by operating temperature and oxygen content. • The sensing property is greatly enhanced after the electrode morphology regulation. • The broken line-shaped sensitivity curve is caused by the gas-phase consumption of ammonia with oxygen. The influences of sensing electrode morphology, operating temperature and the oxygen content on NH 3 sensing properties for the potentiometric gas sensor attached with CeVO 4 sensing electrode were studied. With the increase of electrode sintering temperature, CeVO 4 grains grow up gradually. The response/recovery time shows a decreasing trend, but the NH 3 sensitivity reaches the highest when the sintering temperature reaches 1000 °C, this was determined by the amount of TPB and the ammonia concentration involved in the electrode electrochemical reactions. The NH 3 sensitivity enhances with the increase of operating temperature in the range of 450–550 °C and presents the mixed-potential characteristic. When the temperature exceeds 600 °C, the curve between ΔV and logarithm of NH 3 concentration presents a broken line relationship, and the concentration corresponding to the inflection point increases with the increase of operating temperature. The response and recovery rates accelerate but the NH 3 sensitivity decreases with the increase of oxygen content in testing gas. When the oxygen is above 10 vol.% and NH 3 is below 80 ppm, the response value is almost unaffected by the change of oxygen concentration. The broken line feature of the sensitivity curve under high operating temperatures and oxygen concentrations is mainly related to the gas phase catalytic reaction of NH 3 by oxygen. [ABSTRACT FROM AUTHOR]