Construction of "peptide-hemin/DNA" hybrid-complexes and their peroxidase activities.

N-Acetylated microperoxidase-11 and G-quadruplex DNA are shown to form a stable "peptide-hemin/DNA" hybrid-complex, in which the peroxidase activity at the interface between hemin and the G-quartet planes exponentially increases with increasing Ka value.

Incipient fault diagnosis for the cam-driven absolute gravimeter.

The vibration disturbance caused by incipient faults is an important factor affecting the measurement accuracy of the cam-driven absolute gravimeter. Based on the characteristics of the cam-driven absolute gravimeter, such as the small amplitude of the incipient faults, the inadequate representation of features for the faults, and hard-to-find in the noise, a novel method for incipient fault diagnosis of the cam-driven absolute gravimeter is put forward in this paper, which integrates the parameter-optimized Variational Mode Decomposition (VMD) with Light Gradient Boosting Machine (LightGBM). The sparrow search algorithm is used to optimize the VMD parameters. The parameter-optimized VMD algorithm is used to adaptively decompose the vibration signals of the gravimeter under different cases, and then an effective intrinsic mode function (IMF) is selected based on the Pearson correlation coefficient. Some high-frequency IMFs are subjected to adaptive noise reduction combined with low-frequency IMF reconstruction, and then the multi-scale permutation entropy with sensitive characteristics under different time scales is extracted as the fault feature vectors. The extracted multi-dimensional vector matrix is entered into the LightGBM classifier to realize the accurate diagnosis of the incipient faults for the cam-driven absolute gravimeter. The test results show that this method can effectively detect various incipient failures of the cam-driven absolute gravimeter, with an identification accuracy of 98.41%. With this method, the problem of low measurement accuracy for the cam-driven absolute gravimeter caused by the incipient faults is solved, and the rapid tracing and accurate positioning of these faults for the gravimeter are realized, promising a good prospect for engineering application.

Ultra-stretchable, self-recovering, self-healing cationic guar gum/poly(stearyl methacrylate-co-acrylic acid) hydrogels.

Hydrogels that exhibit properties such as ultra-elongation, self-recovery, and self-healing have applications in sensors and many other fields. With these properties and applications in mind, we hypothesised that we could develop a strain-sensing hydrogel based on acrylic acid, stearyl methacrylate, cationic guar gum, and hexadecyl trimethyl ammonium bromide, without any covalent crosslinker. The hydrogels are instead held together by physical, non-covalent interactions such as ionic interactions, hydrogen bonding, and the hydrophobic effect, as suggested by spectroscopy and swelling experiments. The hydrogels exhibit many useful properties, such as: excellent stretching-up to 4267%-and almost complete reversion to their original state at a large strain of 500%, even after 20 successive cycles; temperature-dependent self-healing and self-recovery; and strain-sensitive conductivity that is attributable to the directional migration of ions. Because of these outstanding features, such as notch-insensitivity and the ability to withstand knotting under high strain, our hydrogels will be useful as flexible sensors.

High strength hydrogels with multiple shape-memory ability based on hydrophobic and electrostatic interactions.

Hydrogels with multiple shape-memory ability have aroused great interest due to their promising applications in various fields. Nevertheless, the weak mechanical performance of most shape-memory hydrogels seriously impedes the practical application in more complex environments. Herein, we reported a novel hydrogel with both high mechanical and multi-shape memory properties composed of stearyl methacrylate (SMA), acrylic acid (AA) and quaternary chitosan (QCH). The electrostatic interactions between AA and QCH together with the hydrophobic interactions of alkyl chains in SMA endowed the hydrogel with great strain-stress and fatigue resistance. Furthermore, due to the reversible destruction and construction of physical cross-links, the prepared hydrogels also exhibited the shape-memory ability in response to different stimuli, such as temperature, pH and NaCl solution. Additionally, the multiple shape-memory effect could be accomplished via programmable combination because of the relatively independent physical interactions in the hydrogels.

Coaxial Dual-wavelength Interferometric Method for a Thermal Infrared Focal-plane-array with Integrated Gratings.

Uncooled infrared (IR) focal-plane-array (FPA) with both large sensing range and high sensitivity is a great challenge due to the limited dynamic range of the detected signals. A coaxial dual-wavelength interferometric system was proposed here to detect thermal-induced displacements of an ultrasensitive FPA based on polyvinyl-chloride(PVC)/gold bimorph cantilevers and carbon nanotube (CNT)-based IR absorbing films. By alternately selecting the two displacement measurements performed by λ1 (=640 nm) and λ2 (=660 nm), the temperature measuring range with greater than 50% maximum sensitivity can be extended by eight-fold in comparison with the traditional single-wavelength mode. Meanwhile, the relative measurement error over the full measuring range is below 0.4%. In addition, it offers a feasible approach for on-line and on-wafer FPA characterization with great convenience and high efficiency.

Benzene sensors based on multi-walled carbon nanotube networks decorated with metal nanoclusters.

This paper demonstrates sensors based on multi-walled carbon nanotube (MWNT) networks decorated with metal nanoclusters for benzene vapor detection at room temperature. MWNT networks were deposited between the interdigitated metal electrodes on a Si/SiO2 substrate by AC dielectrophoresis. Metal nanoclusters including Au, Pt, Ti and Ni were deposited by magnetron sputtering onto the MWNT networks with a controlled loading of equivalent thickness of 1.5-1.8 nm as the active sensing layer. The resistances of MWNT networks are reduced after functionalized with metal nanoclusters. Experimental results show that resistances of unmodified and metal-functionalized MWNT networks increase after exposing to benzene, ethanol and water vapor. The MWNT networks decorated with Au, Pt and Ti have more sensitivity than bare MWNT networks while Ni decoration did not enhance the sensitivity of MWNT networks to benzene vapor. The MWNT networks decorated with Pt exhibited highest resistance response to benzene vapor, with a less interference of ethanol vapor and humidity.