Transparent polyimide/graphene oxide nanocomposite with improved moisture barrier property

Colorless and organo-soluble polyimide (PI) films have been synthesized from an alicyclic dianhydride BCDA and aromatic diamine 3,4′-ODA in the cosolvent of DMAc and GBL via one-step process. The graphene oxide (GO) was mixed with the above PI in DMAc solution to fabricate the PI/GO nanocomposite films. With the addition of only 0.001 wt% of GO in PI matrix, the resultant nanocomposite (PI/GO-0.001) exhibits not only the enhanced resistance to moisture but also retains superior visible light transmission, enhanced mechanical strength, and excellent dimensional stability, simultaneously. The water-vapor-transmission-rate (WVTR) significantly reduced to 30 g mil m⁻² day⁻¹ for this nanocomposite compared to 181 g mil m⁻² day⁻¹ for pure PI. Notably, the PI/GO-0.001 nanocomposite also exhibits low coefficient of thermal expansion (CTE) of 41 ppm °C⁻¹, which is benefited from the homogeneous distribution of ultrathin GO nanosheets in PI matrix.     

Ontology-based fuzzy support agent for ship steering control

The important field of research on ship operation is related to the high efficiency of transportation, the convenience of maneuvering ships, and the safety of navigation. This paper proposes an ontology-based fuzzy support agent for ship steering control and desires to testify the validity of the proposal by applying the fuzzy control model to the steering control system based on linguistic instruction. The fuzzy support agent is presented to build the maneuvering models of steersman and the miniature model for steering control system. The proposed fuzzy agent contains three main mechanisms, including the interpretation mechanism of linguistic instruction, the self-regulation mechanism, and the task performance mechanism. Furthermore, the task performance mechanism includes the kinematics module and the performance ontology. The simulation results show that the proposed approach can work effectively for ship steering control.     

Advanced anticorrosive coatings prepared from electroactive polyimide-TiO2 hybrid nanocomposite materials

In this study, we present the first preparation and corrosion protection studies of a series of electroactive polyimide-TiO₂ (EPTs) hybrid nanocomposite materials containing conjugated segments of electroactive amino-capped aniline trimer (ATs) and TiO₂ nanoparticles of ∼10 nm in diameter. Redox behavior of as-prepared EPTs hybrid materials was identified by electrochemical cyclic voltammetry (CV) studies. Higher concentration of TiO₂ component in as-prepare corresponding EPTs was found to reveal better corrosion protection effect on cold-rolled steel (CRS) electrode based on sequential electrochemical corrosion measurements in 5 wt.% NaCl electrolyte. Enhancement of corrosion protection of EPTs coatings on CRS electrode could be interpreted by following three possible reasons: (1) Electroactive polyimide (EPI) could act as a physical barrier coating. (2) The redox catalytic capabilities of ATs units existed in EPTs may induce the formation of passive metal oxide layers on CRS electrode. (3) The well-dispersed TiO₂ nanoparticles in EPTs matrix could act as effective hinder to enhance the oxygen barrier property of EPTs.     

High temperature lifetime of polyimide/poly(silsesquioxane)-like hybrid films

Decomposition kinetics in thermogravimetric analysis (TGA) and dynamic mechanical relaxation in dynamic mechanical analysis (DMA) are used to study the high temperature lifetime of the new type of polyimide/poly(silsesquioxane)-like (PI/PSSQ-like) hybrid films, which are designed to form three-dimensional structures with linear polyimide blocks and a crosslinked PSSQ-like structure. Both TGA and DMA analysis reveal that the PI/PSSQ-like hybrid films have a longer lifetime (are more reliable) with regard to their thermal and mechanical characteristics than that of pure PI. Even just 2 wt% of p-aminophenyltrimethoxysilane (APTS) in a PI/PSSQ-like hybrid film can significantly improve the service lifetime by as much as at least four times in a TGA decomposition kinetic study. The dynamical relaxation data are well fitted to the calculated WLF (Williams-Landel-Ferry) master curves. In a series of X-PIS (PI modified with APTS) hybrid films, decreasing the PI block chain length increases the decomposition activation energy, lifetime (in both TGA and DMA) and relaxation modulus. In a series of X-PIS-y-PTS [PI modified with APTS and phenyltrimethoxysilane (PTS)] films, the decomposition activation energy and lifetime (in TGA) increase with the PTS content. Interestingly, the dynamic mechanical relaxation modulus of 10000-PIS-100-PTS film is lower than that of the corresponding 10000-PIS film at frequency > 10² rad/sec, but higher at frequency < 10² rad/sec. The 10000-PIS-100-PTS has a lower relaxation time than the 10000-PIS at the modulus 5×10⁸ Pa, but the relaxation time of the former becomes higher at 5×10⁷ Pa.     

A reactive modifier that enhances the thermal mechanical properties of epoxy resin through the formation of multiple hydrogen-bonded network

In this study, we synthesized a reactive modifier [DOPO-tris(azetidine-2,4-dione)], terminated with three azetidine-2,4-dione functional groups, from [(9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)tris(4-aminophenyl)methane; DOPO-triamine] and [4-isocyanato-4′-(3,3-dimethyl-2,4-dioxo-acetidino)diphenylmethane; IDD]. We embedded this reactive modifier, which contains multiple hydrogen bond donor and acceptor units, into epoxy resins to promote intermolecular interactions and to tailor its flexibility through the formation of unique pseudo-crosslinked polymer networks. The resulted epoxy resins were found to exhibit glass transition temperature as high as 187 °C and excellent flame retardancy with limited oxygen index (LOI) values around 38. Meanwhile, the dynamic mechanical analysis (DMA) of epoxy systems increases from 0.67 to 2.13 GPa for storage modulus and 0.73–1.67 GPa for loss modulus at 100 °C. Incorporation of reactive modifier into epoxy networks with noncovalent interactions via thermosetting blend was demonstrated to be an effective way to enhance the thermal and physical properties simultaneously.     

Ontological fuzzy agent for electrocardiogram application

The electrocardiogram (ECG) signal is adopted extensively as a low-cost diagnostic procedure to provide information concerning the healthy status of the heart. However, the QRS complex must be calculated accurately before proceeding with the heart rate variability (HRV). In particular, the R peak needs to be detected reliably. This study presents an adaptive fuzzy detector to detect the R peak correctly. Additionally, an ontological fuzzy agent is presented to process the collection of ECG signals. The required knowledge is stored in the ontology, which comprises some personal ontologies and predefined by domain experts. The ontological fuzzy agent retrieves the ECG signals with R peaks marked for HRV analysis and ECG further applications. It contains a personal fuzzy filter, an HRV analysis mechanism, and a fuzzy normed inference engine. Moreover, the ECG fuzzy signal space and some important properties are presented to define the working environment of the agent. An experimental platform has been constructed to test the performance of the agent. The results indicate that the proposed method can work effectively.     

Contact-free hand geometry-based identification system

This paper presents an approach for personal identification using hand geometrical features, in which the infrared illumination device is employed to improve the usability of this hand recognition system. In the proposed system, prospective users can place their hand freely in front of the camera without any pegs or templates. Moreover, the proposed system can be widely used under dark environment and complex background scenarios. To achieve better detection accuracy, in total 13 important points are detected from a palm image, and 34 features calculated from these points are used to further recognition. Experimental results demonstrate that the averaged Correct Identification Rate (CIR) is 96.23% and averaged False Accept Rate (FAR) is 1.85%. These results prove that the proposed contact-free system can be considered as an effective identity verification system for practical applications.     

Electrochemical studies on aniline-pentamer-based electroactive polyimide coating: Corrosion protection and electrochromic properties

In this study, electrochemical investigations of corrosion protection and the electrochromic properties of an aniline-pentamer-based electroactive polyimide (AP-based EPI) coating prepared by oxidative coupling polymerization are presented. The in situ chemical oxidation of the reduced form of soluble, electroactive poly(amic acid) (EPAA) in N-methyl-2-pyrrolidone (NMP) was monitored by UV–Vis absorption spectra. Moreover, the electroactivity of the AP-based EPI was evaluated by performing electrochemical CV studies. Based on a series of electrochemical measurements in 3.5 wt% NaCl electrolyte, the AP-based EPI coating was found to exhibit enhanced corrosion protection effects on cold-rolled steel (CRS) electrodes as compared to the corresponding non-electroactive (NEPI) coating. A possible mechanism for the enhanced corrosion protection of EPI coatings on the CRS electrode has been proposed as follows: (1) EPI coatings may act as a physical barrier and (2) the redox catalytic properties of the aniline pentamer units in EPI may induce the formation of a passive metal oxide layer on the CRS electrode, as evidenced by SEM and ESCA studies. The electrochromic performance of EPI was investigated by measuring electrochromic photographs and UV absorption spectra.     

Injurious Effects of Emodin on Maturation of Mouse Oocytes,Fertilization and Fetal Development via Apoptosis

Emodin (1,3,8-trihydroxy-6-methylanthraquinone), a major constituent of rhubarb, has a wide range of therapeutic applications. Previous studies have established that emodin induces apoptosis in the inner cell mass and trophectoderm of mouse blastocysts and leads to decreased embryonic development and viability, indicating a role as an injury risk factor for normal embryonic development. However, the mechanisms underlying its hazardous effects have yet to be characterized. In the current study, we further investigated the effects of emodin on oocyte maturation and subsequent pre- and post-implantation development, both in vitro and in vivo. Notably, emodin induced a significant reduction in the rates of oocyte maturation, fertilization, and in vitro embryonic development. Treatment of oocytes with emodin during in vitro maturation (IVM) led to increased resorption of postimplantation embryos and decreased fetal weight. Experiments using an in vivo mouse model disclosed that consumption of drinking water containing 20–40 μM emodin led to decreased oocyte maturation and in vitro fertilization, as well as early embryonic developmental injury. Notably, pretreatment with a caspase-3-specific inhibitor effectively prevented emodin-triggered injury effects, suggesting that impairment of embryo development occurs via a caspase-dependent apoptotic process.     

Automatic measurement of runway grooving construction for pavement skid evaluation

Grooved construction on airport runways has been proven to greatly improve the drainage efficiency and skid resistance of pavement. However, there exist very few measurement methodologies that are capable of successfully assessing information about the grooves other than manual random sampling. An automatic measuring instrument equipped with a laser displacement sensor and an accelerometer mounted on a low-speed scooter is developed in this study. Pilot simulation tests were conducted first to study the feasibility and reliability of the instrument. The mean error percentage of the instrument is 2.27%, 4.45%, and 3.14% in measuring depth, width, and spacing, respectively, which indicates that the developed instrument can provide a relatively reliable accuracy in the measurement of groove sizes. Groove configuration and skid resistant capability of two airport runways were measured, and the result obtained from field experiments showed that the quality of grooving construction is crucial to skid resistance of pavement. Preliminary studies show promising results in enhancing the efficiency of the evaluation of grooved pavement.