Synergistic effects of zinc oxide in montmorillonite flame‐retardant polystyrene nanocomposites

In this study, two‐dimensional organic montmorillonite (OMMT) and one‐dimensional needlelike ZnO were used as flame retardants of polystyrene (PS). Polystyrene/organic montmorillonite (PMT) and polystyrene/organic montmorillonite/zinc oxide nanocomposites (PMZs) with different weight ratios were prepared by melt intercalation. Information on the morphologies and structures of the PS nanocomposites was obtained with Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that a mixed exfoliated–intercalated structure was observed in the PMT and PMZs. Dynamic mechanical thermal analysis showed that both the storage modulus and glass‐transition temperature values of the PMT and PMZs were significantly improved compared with those of the neat PS. The mechanical property tests showed that the bending modulus values of both PM5 (PS/OMMT weight ratio = 95:5) and PMZs increased compared with that of pristine PS. PMZ1 (PS/OMMT/ZnO weight ratio = 94:5:1) provided no decrease in the tensile strength in comparison with PS. A synergistic effect was observed between OMMT and ZnO; this resulted in improvements in the flame retardancy and dynamic mechanical properties in the PMZs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43047.     

Investigation of epoxy‐resin‐modified asphalt binder

Epoxy asphalt (EA) binder has been used extensively for paving long‐span bridges in many countries because it shows excellent heat resistance, is free from bleeding, has a low‐temperature cracking resistance, and has aggregate scattering resistance. EA binders were prepared by the mixture of asphalt, epoxy resin, and a new curing agent (CR) with functional groups. The properties of the EA binder were characterized by their viscosity, tensile strength, elongation at break, compatibility, morphology, glass transition temperature (T_g), contact angle, and surface free energy. The curing process was analyzed. The results indicate that the curing temperature and asphalt content had significant effects on the properties of the EA binder. We observed that most of the strength was generated after the first 3 h at 165 °C; this provided good workability for EA pavement construction. The CR with various functional groups improved the compatibility and morphology of the EA binder. The test results show that T_g of the EA binder decreased and the contact angles increased with increasing asphalt content. It is worth noting the contact angles between water and the EA binder were always greater than 90°; this implied that the EA binder was hydrophobic and, hence, water repellent. The surface free energy and dispersion force increases with decreasing asphalt content. However, the polarity forces decreased with decreasing asphalt content. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43401.     

n-3 Polyunsaturated Fatty Acids Improve Inflammation via Inhibiting Sphingosine Kinase 1 in a Rat Model of Parenteral Nutrition and CLP-Induced Sepsis

The sphingosine kinase 1 (SphK1)/sphingosine‐1‐phosphate (S1P) pathway plays a key role in inflammation. Parenteral nutrition containing n‐3 polyunsaturated fatty acids (n‐3 PUFA) may regulate inflammatory reactions. The aim of this study is to determine whether n‐3 PUFA may improve inflammatory responses by neutralizing SphK1 signaling. Rat models of parenteral nutrition, cecal ligation and puncture (CLP)‐induced sepsis were generated. Male Sprague–Dawley rats were operated for CLP on day 2 after venous catheterization. The rats were randomized to receive normal saline (NS; n = 20), parenteral nutrition (PN; n = 20), or PN + fish oil (FO; n = 20) for 5 days. The daily intake of fish oil (1.25–2.82 g EPA and 1.44–3.09 g DHA per 100 ml) in the FO group was approximately 1.8 g/kg body weight/day. Rats in the control group (n = 10) were subjected to sham operation and received a chow diet. Spleen tissues were collected for SphK1 and S1P receptor expression analysis. Our data showed that n‐3 PUFA ameliorated the survival rate. SphK1 expression and its enzymatic activity were significantly upregulated in sepsis rats. Furthermore, mRNA and protein levels of S1PR3, but not S1PR1, were also facilitated after CLP. However, PN + FO dramatically decreased SphK1 mRNA level and its enzymatic activity. S1PR3 expression was also attenuated by FO addition. In conclusion, the anti‐inflammatory effect of n‐3 PUFA may be linked to the inhibition of the SphK1/S1P pathway in a rat model of parenteral nutrition and CLP‐induced sepsis.     

Dietary Arachidonic Acid Has a Time-Dependent Differential Impact on Adipogenesis Modulated via COX and LOX Pathways in Grass Carp Ctenopharyngodon idellus

In this study, we explored the function of arachidonic acid (ARA) in adipogenesis in the grass carp (Ctenopharyngodon idellus) using in vivo and in vitro models. An 8‐week feeding trial was performed using three isonitrogenous and isoenergetic purified diets: ARA‐free, ARA, and ARA + acetylsalicylic acid [ASA, a cyclooxygenase (COX) inhibitor]. Fish were sampled after 4 and 8 weeks of feeding. Results showed that ARA‐fed fish had a significantly lower intraperitoneal fat index (IPFI) and smaller adipocytes; these decreases were reversed by ASA after 8 weeks of feeding. Nevertheless, at week 4, the IPFI and adipocyte size were higher in the ARA group, and they were comparable to those of fish fed ARA + ASA. To further investigate the influence of ARA on adipocyte differentiation, confluent pre‐adipocytes of grass carp were incubated with ARA for 3 days. This in vitro experiment demonstrated that ARA promoted adipogenesis in a dose‐dependent manner. Pre‐treatment with the lipoxygenase (LOX) inhibitor nordihydroguaiaretic acid attenuated the pro‐adipogenic function of ARA. However, after treatment with ARA for 8 days, adipocytes had a lower lipid content than cells treated with oleic acid, and ASA could suppress this effect. We thus revealed the dual function of ARA in adipogenesis in grass carp. The LOX pathway may play a key role in pro‐adipogenesis after short‐term treatment with ARA, whereas the COX pathway is possibly responsible for the inhibition of adipogenesis after long‐term treatment.     

Fe‐substituted Ba‐hexaaluminates oxygen carrier for carbon dioxide capture by chemical looping combustion of methane

Fe‐substituted Ba‐hexaaluninates (BFA‐x (x = 1–3), x indicates Fe content) oxygen carrier (OC) were found to exhibit excellent sintering‐resistance under cyclic redox atmosphere at 800°C thanks to the reservations of the structure during the CH₄ reduction step, thus preventing the agglomeration of particles during the subsequent reoxidation step. Lattice oxygen highly active for the total combustion of CH₄ was observed in the hexaaluminate structure and its chemical state was influenced by Fe content. The highest amount of active O coordinated with Fe³⁺ in the mirror plane (O‐Fe³⁺(M)) for the total combustion was reacted (0.77 mmol/g) for BaFe₃Al₉O₁₉ hexaaluminate OC. As a result, it exhibited the best reactivity with the CH₄ conversion of 83% and CO₂ selectivity of 100%. Moreover, superior regeneration and recyclability was also obtained, which originated from the fully recovery of O‐Fe³⁺(M) in the hexaaluminate structure. © 2015 American Institute of Chemical Engineers AIChE J, 62: 792–801, 2016     

Charged groups synergically enhance protein imprinting in amphoteric polyacrylamide cryogels

Proteins are amphoteric biopolymers with unevenly charged exterior surfaces. Taking this point fully into account could accomplish ingenious recognition systems for the biological macromolecues. Molecularly imprinted polymers (MIPs) are good tools to study the interactions between polymeric matrices and template molecules. Here different protein imprinted cryogels were prepared. Imprinting factors (IFs) were determined with bovine serum albumin (BSA) as the template. The IF of the polymeric cryogel made from only acrylamide (AM) and N,N′‐methylenebisacrylamide (BisAM) is about 1.38. The introduction of charged monomers, either acrylic acid or diallylamine, would increase IFs obviously. One of the basic cryogels gave the maximum IF (about 2.0) of that type. As both acrylic acid and diallylamine were involved, IFs were further increased. An amphoteric cryogel with a suitable acid‐base ratio gave a high IF of about 3.7. Whatever used alone or both, too many added acidic or basic monomers resulted in IF reduction. Taking full advantage of charged groups in MIPs could be a good way to manipulate protein–polymer interactions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43851.     

Mechanical Alloying and Spark Plasma Sintering of BiCuSeO Oxyselenide: Synthesis Process and Thermoelectric Properties

BiCuSeO is a promising thermoelectric material but needs a complicated synthesis process. In this work, fine‐grained BiCuSeO samples with high phase purity were synthesized by a combination of mechanical alloying (MA) and spark plasma sintering (SPS). It is found that BiCuSeO compounds can be formed by the reaction between BiSe and CuO, after BiSe appeared firstly when using Bi, Se, and CuO as raw materials during MA process. The electrical conductivity of the corresponding bulk attains a modest enhancement due to the significantly increased carrier concentration although the carrier mobility was reduced compared with the sample prepared by classical solid‐state reaction. The total thermal conductivity is below 0.7 W/mK in the whole measured temperature range, which is attributable to the increased defects and gain boundaries. As a result, a relatively high ZT value of 0.50 was obtained for the pristine BiCuSeO sample. In addition, when Bi was replaced by Ca element, the electrical transport property of the samples was improved, resulting in an enhancement of ZT in the whole measured temperature range.     

Mechanism and properties of coloured nanoscale SiO2 prepared from silica and reactive dyes

KH560‐modified SiO₂ was prepared using tetraethyl orthosilicate (TEOS) and γ‐(2,3‐epoxypropoxy) propytrimethoxysilane (KH560) by the sol–gel method and then coloured with CI Reactive Blue 4 (X‐BR) to prepare coloured nanoscale SiO₂. The antisolvent performance and the results of cross‐polarisation/magic angle spinning ¹³C nuclear magnetic resonance and Fourier transform infrared spectroscopy showed that the reaction of X‐BR with KH560‐modified SiO₂ is a two‐step process: X‐BR is firstly adsorbed by KH560‐modified SiO₂ via van der Waals forces, and then nucleophilic substitution occurs between dichloro triazine and the epoxy group. The grafting ratio of X‐BR on KH560‐modified SiO₂ reached 95% under optimum conditions, i.e. a mass ratio of KH560 to TEOS of 20%, a temperature of 40 °C, a pH of 8.5, and a reaction time of 5 h. X‐ray diffraction analysis and transmission electron microscopy showed that the coloured nanoscale SiO₂ was amorphous, with a mean diameter of 216 nm. Experimental application showed that the coloured nanoscale SiO₂ had excellent stability to solvents and alkaline solution, and the absorptive capacity of the coloured nanoscale SiO₂ in the 200–400 nm region was higher than that of X‐BR. The light fastness of the coloured nanoscale SiO₂ reached 5–6 grade.     

高温服役构件蠕变状态参数化表征技术研究进展

概述了已有高温服役构件蠕变状态参数化表征技术的特点及其表征参数。主要介绍了传统检测技术中的超声波速法、X射线衍射技术和磁巴克豪森发射技术,以及近年来出现的电磁超声谐振(EMAR)和非线性超声(NLU)技术。通过对上述方法的系统分析与比较,最后指出将EMAR和NLL技术的有机结合将成为高温服役构件蠕变状态参数化袁征的有力工具。     

Structural synthesis of a class of 2R2T hybrid mechanisms

Conventional overconstrained parallel manipulators have been widely studied both in industry and academia, however the structural synthesis of hybrid mechanisms with additional constraints is seldom studied, especially for the four degrees of freedom(DOF) hybrid mechanisms. In order to develop a manipulator with additional constraints, a class of important spatial mechanisms with coupling chains(CCs) whose motion type is two rotations and two translations(2R2T) is presented. Based on screw theory, the combination of different types of limbs which are used to construct parallel mechanisms and coupling chains is proposed. The basic types of the general parallel mechanisms and geometric conditions of the kinematic chains are given using constraint synthesis method. Moreover, the 2R2T motion pattern hybrid mechanisms which are derived by adding coupling chains between different serial kinematic chains(SKCs) of the corresponding parallel mechanisms are presented. According to the constraint analysis of the mechanisms, the movement relationship of the moving platform and the kinematic chains is derived by disassembling the coupling chains. At last, fourteen novel hybrid mechanisms with two or three serial kinematic chains are presented. The proposed novel hybrid mechanisms and construction method enrich the family of the spatial mechanisms and provide an instruction to design more complex hybrid mechanisms.