Thermal degradation behavior of multi-walled carbon nanotubes/polyamide 6 composites

This paper focuses on the thermal degradation behavior of multi-walled carbon nanotubes (MWNTs)/polyamide 6 (PA6) composites under air and nitrogen atmosphere using thermogravimetric analysis (TGA). The results show that the dispersion of amino-functionalized MWNTs (f-MWNTs) in PA6 is more homogeneous than purified MWNTs (p-MWNTs). The presence of MWNTs improves the thermal stability of PA6 under air obviously, but has little effect on the thermal degradation behavior of PA6 under nitrogen atmosphere. The activation energies for degradation under air, E_a, estimated by Kissinger method, are 153, 165 and 169 kJ/mol for neat PA6, p-MWNTs/PA6 and f-MWNTs/PA6 composites, respectively. The p-MWNTs/PA6 composites show two-step degradation not only under air but also under nitrogen atmosphere, however, neat PA6 and the f-MWNTs/PA6 composites exhibit two-step degradation only under air.     

Metabolite identification of the antimalarial piperaquine in vivo using liquid chromatography–high‐resolution mass spectrometry in combination with multiple data‐mining tools in tandem

Artemisinin‐based combination therapy is widely used for the treatment of uncomplicated Plasmodium falciparum malaria, and piperaquine (PQ) is one of important partner drugs. The pharmacokinetics of PQ is characterized by a low clearance and a large volume of distribution; however, metabolism of PQ has not been thoroughly investigated. In this work, the metabolite profiling of PQ in human and rat was studied using liquid chromatography tandem high‐resolution LTQ‐Orbitrap mass spectrometry (HRMS). The biological samples were pretreated by solid‐phase extraction. Data processes were carried out using multiple data‐mining techniques in tandem, i.e., isotope pattern filter followed by mass defect filter. A total of six metabolites (M1–M6) were identified for PQ in human (plasma and urine) and rat (plasma, urine and bile). Three reported metabolites were also found in this study, which included N‐oxidation (M1, M2) and carboxylic products (M3). The subsequent N‐oxidation of M3 resulted in a new metabolite M4 detected in urine and bile samples. A new metabolic pathway N‐dealkylation was found for PQ in human and rat, leading to two new metabolites (M5 and M6). This study demonstrated that LC‐HRMSⁿ in combination with multiple data‐mining techniques in tandem can be a valuable analytical strategy for rapid metabolite profiling of drugs. Copyright © 2016 John Wiley & Sons, Ltd.     

Poly(phenylene oxide) modified cyanate resin for self‐healing

Self‐healing cyanate ester resins (CE) were developed by adding low molecular weight poly(phenylene oxide) (PPO) resin, yielding a high performance CE/PPO system via a low‐temperature process. The addition of PPO improved the flexural strength and fracture toughness of the CE matrix without sacrificing thermal properties. CE/PPO formulations with 5, 10, and 15 wt.% PPO showed 43%, 65%, and 105% increase in fracture toughness due to a combination of crack deflection, crack pinning, and matrix cavitation around second‐phase particles. When PPO was introduced into the CE, dielectric properties were either unchanged or declined. During thermal treatment to heal damaged CE, liquid PPO flowed into cracks, and during subsequent cooling, solidified to bond the crack surfaces. The self‐healing efficiency for CE with 15 wt.% PPO after heating to 220°C for 1 h exhibited a recovery of 73% in toughness and 81% in microtensile strength. Copyright © 2014 John Wiley & Sons, Ltd.     

Breath Figure Arrays: Unconventional Fabrications,Functionalizations, and Applications

A breath figure (BF) is the water droplet array that forms when moisture comes in contact with a cold substrate. This water droplet array has been widely utilized in the past two decades as a versatile soft template for the fabrication of polymeric porous films. Accordingly, the ordered pores on the polymer films formed with such a method are named a breath figure array (BFA).The BF templating technique is undergoing rapid development. Several unconventional BF processes have been established to prepare porous films with unique morphologies or primary materials, and various newly developed functionalization techniques have significantly improved the performance of polymeric films with BFA, leading to novel applications, including templates, biosensors, and separation membranes. These recent achievements will be described in this Minireview.     

Improved microhardness and microtribological properties of bismaleimide nanocomposites obtained by enhancing interfacial interaction through carbon nanotube functionalization

Through the functionalization of multiwalled carbon nanotubes (MWCNTs) by 0,0′‐diallylbisphenol A (DBA), the interface situation between MWCNTs and bismaleimide (BMI) was improved, as detected by scanning electron microscope (SEM) and dynamic mechanical analysis (DMA). The improved interface situation was considered to be the main reason for the huge increased microhardness value and greatly improved the microtribological property of MWCNTs/BMI composites. Besides, the wear mechanism for the composite was also believed to be related to the interfacial situation. The rough wavelike worn surface of pure BMI resin is attributed to its poor load capacity. The smoother waterfall‐shape worn surface of MWCNTs/BMI is related to the interface formed by the addition of MWCNTs while the ultrasmooth worn surface of DBA modified MWCNTs/BMI is due to the greatly improved interfacial interaction of the composite. Copyright © 2008 John Wiley & Sons, Ltd.     

Dynamic mechanical properties of aluminum nitride/cyanate ester composites for high performance electronic packaging

Viscoelastic ature is one of the key features of polymeric composites. A series of cyanate ester (CE)‐based composites with different aluminum nitride (AlN) contents for high performance electronic packaging, coded as AlN/CE, were developed; the viscoelastic nature of AlN/CE composites was intensively investigated by employing dynamic mechanical analysis (DMA). Results show that the AlN content has a great effect on dynamic mechanical properties of AlN/CE composites. The storage modulus in the glassy region increases linearly with the addition of AlN as well as the increase of AlN content. Meanwhile, all composites also exhibit notably higher loss modulus than cured CE resin due to the appearance of new energy dissipation forms. In addition, the incorporation of AlN has a significant effect on damping factor peak. All reasons leading to these phenomena are analyzed from the view of structure–property relationship. Copyright © 2009 John Wiley & Sons, Ltd.     

A novel organic rectorite modified bismaleimide/diallylbisphenol A system

4,4′‐Bismaleimidodiphenylmethane (BMIPM)/O,O′‐diallylbisphenol A (BA) system was modified by organic rectorite (OREC) to develop a novel BMI/BA/OREC nanocomposite. The effect of OREC on the viscosity and reactivity of BMIPM/BA system was investigated. The mechanical properties of BMIPM/BA/OREC composites such as the flexural and impact strength were evaluated. The morphology of cured BMIPM/BA/OREC systems was investigated by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The hot water resistance of BMIPM/BA/OREC systems was discussed. The thermal property of BMIPM/BA/OREC systems was investigated using thermogravimetric analysis (TGA). The dynamic mechanical properties of BMIPM/BA/OREC systems were also measured. Results show that the addition of OREC has a significant influence on the reactivity of the BMIPM/BA system. Proper content of OREC can improve the flexural strength, impact strength, and hot water resistance of a BMIPM/BA system. The addition of OREC cannot decrease the thermal degradation temperature of cured BMIPM/BA system with a slight sacrifice of the glass transition temperature (Tg). Copyright © 2008 John Wiley & Sons, Ltd.     

Electrochemical Studies of Anticancer Herbal Drug Sophoridine and Its Interaction with DNA

Sophoridine is a new anticancer herbal drug with remarkable antitumor effect and lower toxicity. In this paper, the electrochemical investigation of sophoridine and its interaction with DNA is reported. In 0.1 mol L^?1 phosphate buffer solution (pH 7.0), sophoridine exhibited excellent electrochemical activity. In the presence of DNA, the peak current of sophoridine decreased in a quantitative fashion and the peak potential shifted to a more positive potential value. It suggests the dominance of intercalative interaction. Importantly, as to the interaction between sophoridine and DNA in solution, characteristic parameters such as the binding stoichiometry and association equilibrium constant according to the Hill model for cooperative binding have been determined.     

彩色照片制作技术

彩色照片由于色彩鲜艳．形象逼真，在工农业生产、科研和日常生活中得到广泛应用。本文就校正偏色与曝光谈一下自己的看法。