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Streptococcus suis serotype 2 (SS2), an emerging zoonotic pathogen, may induce severe infections and symptoms manifested as septicemia, meningitis and even death both in human and pigs. The aim of this article was to develop a new methodology as real-time recombinase polymerase amplification (RT-RPA) assay targeting cps2J gene for the detection of SS2 (or SS1/2). The sensitivity and reproducibility of RT-RPA results were evaluated and compared with a real-time quantitative PCR (RT-qPCR). The established RT-RPA reaction could be completed in 20 minutes with distinguishable specificity against the predominant S. suis infection serotypes of 3, 4, 5, 7, 9, 14 and 31. Lower detection limit for RT-RPA was 102 genomic DNA copies per reaction. The specimen performance of RT-RPA was tested in nasopharyngeal swab samples with the sensitivity and specificity as 97.5% and 100%, respectively. Thus this RT-RPA method is a rapid and potential molecular diagnostic tool for SS2 detection.

Dendritic cell-based cancer vaccines (DC vaccines) have been proved efficient and safe in immunotherapy of various cancers, including melanoma, ovarian and prostate cancer. However, the clinical responses were not always satisfied. Here we proposed a novel strategy to prepare DC vaccines. In the present study, a fusion protein SNU containing a secretin-penetratin (SecPen) peptide, NY-ESO-1 and ubiquitin was designed and expressed. To establish the DC vaccine (DC-SNU), the mouse bone marrow-derived DCs (BMDCs) were isolated, pulsed with SNU and maturated with cytokine cocktail. Then peripheral blood mononuclear cells (PBMCs) from C57BL/6 mice inoculated intraperitoneally with DC-SNU were separated and cocultured with MC38/MC38NY-ESO-1 tumor cells or DC vaccines. The results show that SNU was successfully expressed. This strategy made NY-ESO-1 entering cytoplasm of BMDCs more efficiently and degraded mainly by proteasome. As we expected, mature BMDCs expressed higher CD40, CD80 and CD86 than immature BMDCs. Thus, the PBMCs released more IFN-γ and TNF-α when stimulated with DC-SNU in vitro again. What's more, the PBMCs induced stronger and specific cytotoxicity towards MC38NY-ESO-1 tumor cells. Given the above, it demonstrated that DC-SNU loaded with SecPen and ubiquitin-fused NY-ESO-1 could elicit stronger and specific T cell immune responses. This strategy can be used as a platform for DC vaccine preparation and applied to various cancers treatment., Graphical abstract NY-ESO-1 was fused with SecPen and ubiquitin for the preparation of dendritic cell (DC) vaccine, which induced a stronger and specific T cell immune response. This strategy for DC vaccine construction can be applied as a platform and used for various cancers treatment.Image 1

An efficient technique to fabricate BiCuSeO oxyselenides thermoelectric bulks is studied. Pb doped p-type BiCuSeO ingots are synthesized by microwave processing for 4 minutes and the bulk materials with 8.7~8.9 gcm−3 density are produced after spark plasma sintering for 5 minutes. The XRD and XPS detection results show that all the samples have nearly a single phase indexed to tetragonal BiCuSeO, and the peak positions of Pb 4f7/2 and 4f5/2 simple spin-orbit doublet peaks in Bi0.98Pb0.02CuSeO and Bi0.90Pb0.10CuSeO respectively are 137.93 and 142.76 eV, and 137.49 and 142.49 eV. Holes are the majority carriers with concentrations of 3.22 1020cm−³ ~2.40 1021cm−³ in the doped samples. Bi0.98Pb0.02CuSeO shows the highest ZT of 0.76 at 773 K and possible larger values can be achieved at a higher temperature. The fabricate technique described here showing great prospect in the research and manufacturing of thermoelectric bulks.

A supercritical H2O/CO2 turbine is a key piece of equipment for the coal gasification in the supercritical water (CGSW) cycle to achieve conversion of heat into power. Compared with a traditional steam turbine, the working medium of an H2O/CO2 turbine has a relatively high CO2 concentration. In the initial condensation zone (ICZ), steam condenses into droplets on the turbine blades and the droplets combine with CO2 to form carbonic acid, which corrodes the turbine blades. In order to research the characteristics of acid corrosion in the ICZ of a H2O/CO2 turbine, the acid corrosion rate of the blades in the ICZ of the H2O/CO2 turbine was calculated and analyzed based on the three-dimensional CFD (3D CFD) method and a one-dimensional numerical model of CO2 corrosion. The results suggest that acid corrosion rates decrease stage by stage in the ICZ due to the reduction in temperature and pressure. Rotor blades in the first stage in the ICZ suffer the worst and form a corrosion zone at the trailing edge of the blade and on the pressure surface. The decline of efficiency caused by corrosion settles down to a relatively steady value of 0.6% for a 10 year service time. Moreover, the corrosion area for the last two stages shrinks with the service time due to the rearward movement of the ICZ.

The preparation of well-defined block copolymers from both non-conjugated and conjugated monomers is still challenging. In this work, a typical block copolymer poly(vinyl acetate) (PVAc)-b-polystyrene (PS) was successfully synthesized by using a successive iniferter strategy. Herein, PVAc was first obtained in the presence of an iniferter agent (e.g., 1-cyano-1-methylethyldiethyldithiocarbamate (MANDC), 2-(N,N-diethyldithiocarbamyl)-isobutyric acid ethyl ester (EMADC) or 2-(ethoxycarbonothioyl)sulfanyl propanoate (EXEP)). Then the resultant PVAc with high end-group functionalities could be used as an effective macroiniferter agent for the polymerization of styrene (St). The kinetic studies of the chain extension experiment with St indicated the “living” features of the polymerization system. In addition, the obtained PVAc-b-PS copolymers could be easily converted into PVA-b-PS amphiphiles by methanolysis of the poly(vinyl acetate) block. Importantly, the synthesis of the copolymers just uses a single simple and metal-free catalyzed polymerization method, which may be of great potential for industrial production.

Streptococcus suis serotype 2 (S. suis 2) is a major zoonotic pathogen. Parvulin-type peptidyl-prolyl isomerase (PrsA) in S. suis 2 is found surface-associated, pro-inflammatory and cytotoxic. To further explore the roles of PrsA in S. suis 2 infection, we constructed a prsA deletion mutant (ΔprsA) and a complemented strain (CΔprsA). The ΔprsA mutant showed increased length of bacterial chains and decreased growth. Deletion of prsA increased bacterial adhesion to host epithelial cells but with weakened invasion. The ΔprsA mutant had reduced survival in RAW264.7 macrophages and pig whole blood, and significantly attenuated in virulence to mice. All these phenotypes of the mutant could be reversed largely to the levels of its parental strain by gene complementation. Western blotting revealed that suilysin was markedly reduced both in surface-associated (SAP) and secreted fractions (SecP) of ΔprsA, which might be responsible for reduced hemolytic activity. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and enolase were significantly increased in both SAP and SecP fractions as a result of prsA deletion. Increased adhesion of the ΔprsA mutant to bEND.3 cells was prevented using polyclonal antibodies against GAPDH and enolase. Overall, we propose that S. suis 2 deploys PrsA to control translocation of important virulence factors, thereby favoring its survival in the host with enhanced pathogenicity by compromising its interactions with the host cells. Further investigation is required to find out how PrsA modulates protein translocation to benefit S. suis infection and if there are other S. suis 2 substrates of potential virulence regulated by PrsA.

The generation method and analysis of solitary waves are always a hotspot of exploring the generation theory of the huge waves that generated by tsunami or windstorm and their destructiveness for experiment and teaching. The key to analyze the interaction between extreme waves and engineering structures is simulating the solitary waves accurately. To lessen the modifications of the simulation of solitary waves in experiment and teaching, the mathematical modelling of the generation of solitary waves controlled by electro-hydraulic proportional control system under constant pressure was proposed, and the motion process of plate and the motion law of the spool valve under different generating conditions were analyzed. The results show that under big immersed depth of plate, to achieve certain height of solitary waves, the bigger the displacement of the plate, the smoother of its motion; under same condition, the maximum displacement of spool valve is bigger when the height is bigger and the immersed depth of plate and oil supply pressure are smaller; under certain wave height, the motion of spool valve is smoother when the immersed depth of plate and oil supply pressure are bigger. The research results have a great significance for conducting the control of spool valve and plate in electrohydraulic system.

PrsA, a peptidyl isomerase encoded by the prsA gene, plays pleiotropic roles in bacterial physiology and pathogenicity. This study was attempted to characterize the distribution of prsA in different serotypes of Streptococcus suis isolates and on the bacterial cells and to evaluate its immunogenicity in a murine model. PrsA is present in different S. suis types and surface-associated as tested in a S. suis type 2 strain. The prsA gene from the serotype 2 strain was cloned for its expression in Escherichia coli. Recombinant PrsA (SsPrsA) showed good reactivity with anti-sera to S. suis serotype 2 and 9 strains. Immunization of mice with SsPrsA elicited a significant antibody response and conferred partial protection against lethal challenge with a S. suis serotype 2 strain (50% protection) or a serotype 9 strain (66% protection). The anti-SsPrsA sera showed good reactivity to the surface-associated proteins of both serotype 2 and serotype 9 strains. Higher abundance of surface-associated PrsA in the serotype 9 strain (than the serotype 2 strain) might account, in part, for higher protection against its challenge infection. These results suggest that SsPrsA may serve as a novel subunit vaccine candidate with cross-protective potential.

Photoinduced initiators for continuous activator regeneration atom transfer radical polymerization (ATRP) of hydrophilic monomers in heptane/ethanol latent-biphasic system for copper catalyst separation and recycling have been realized for the first time at room temperature with different wavelengths of visible light LED (green, blue, purple, and white LED) as external stimulus, using 2-bromophenylacetate as the ATRP initiator and camphorquinone/triethylamine as the photoinitiator. In this system, hybrid catalyst complex (HCc) is synthesized as a novel nonpolar catalyst, which is preferentially dissolved in heptane. The hydrophilic polymers obtained catalyzed by HCc in heptane/ethanol mixture solvent show typical "living" features, for example, the values of Mn,GPC increase linearly with monomer conversion up to quantitative level (>96%) and the molecular weight distributions were kept narrow (Mw /Mn < 1.20) throughout the polymerization process. It should be noted that the excellent controllability of this novel polymerization system can be achieved even after 5 catalyst recycling experiments under LED irradiation.

How to simply and efficiently separate and recycle catalyst has still been a constraint for the wide application of atom transfer radical polymerization (ATRP), especially for the polymerization systems with hydrophilic monomers because the polar functional groups may coordinate with transition metal salts, resulting in abundant catalyst residual in the resultant water-soluble polymers. In order to overcome this problem, a latent-biphasic system is developed, which can be successfully used for ATRP catalyst separation and recycling in situ for various kinds of hydrophilic monomers for the first time, such as poly(ethylene glycol) monomethyl ether methacrylate (PEGMA), 2-hydroxyethyl methacrylate (HEMA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), N,N-dimethyl acrylamide (DMA), and N-isopropylacrylamide (NIPAM). Herein, random copolymer of octadecyl acrylate (OA), MA-Ln (2-(bis(pyridin-2-ylmethyl)amino)ethyl acrylate), and POA-ran-P(MA-Ln) is designed as the macroligand, and heptane/ethanol is selected as the biphasic solvent. Copper(II) bromide (CuBr2 ) is employed as the catalyst, PEG-bound 2-bromo-2-methylpropanoate (PEG350 -Br) as the water-soluble ATRP initiator and 2,2'-azobis(isobutyronitrile) (AIBN) as the azo-initiator to establish an ICAR (initiators for continuous activator regeneration) ATRP system. Importantly, well-defined water-soluble polymers are obtained even though the recyclable catalyst is used for sixth times.

To examine if the molecular chaperone DnaK operon proteins of Streptococcus suis type 2 (SS2) are involved in adhesion to host cells, the abundance values of these proteins from the surface of two SS2 strains of different adhesion capability were compared. Their roles in growth and adhesion to human laryngeal epithelial cell line HEp-2 cells were investigated on SS2 strain HA9801 and its mutants with DnaK operon genes partially knocked-out (PKO mutant) under heat stress. The major difference was that DnaJ was more abundant in strain HA9801 than in strain JX0811. Pretreatment of the bacteria with hyperimmune sera to DnaJ, but not with those to other proteins, could significantly reduce SS2 adhesion to HEp-2 cells. PKO of dnaJ g ene resulted in decreased SS2 growth at 37 °C and 42 °C, and reduced its adhesion to HEp-2 cells. The wild-type strain stressed at 42 °C had increased expression of DnaJ on its surface and elevated adhesion to HEp-2 cells, which was also inhibitable by DnaJ specific antiserum. These results indicate that the DnaJ of S. suis type 2 is important not only for thermotolerance but also for adhesion to host cells. Because DnaJ expression is increased upon temperature upshift with increased exposure on the bacterial surface, the febrile conditions of the cases with systemic infections might help facilitate bacterial adhesion to host cells. DnaJ could be one of the potential candidates as a subunit vaccine because of its good immunogenicity.

Atom transfer radical polymerization (ATRP) is a versatile and robust tool to synthesize a wide spectrum of monomers with various designable structures. However, it usually needs large amounts of transition metal as the catalyst to mediate the equilibrium between the dormant and propagating species. Unfortunately, the catalyst residue may contaminate or color the resultant polymers, which limits its application, especially in biomedical and electronic materials. How to efficiently and economically remove or reduce the catalyst residue from its products is a challenging and encouraging task. Herein, recent advances in catalyst separation and recycling are highlighted with a focus on (1) highly active ppm level transition metal or metal free catalyzed ATRP; (2) post-purification method; (3) various soluble, insoluble, immobilized/soluble, and reversible supported catalyst systems; and (4) liquid-liquid biphasic catalyzed systems, especially thermo-regulated catalysis systems.

A concept based on diffusion-regulated phase-transfer catalysis (DRPTC) in an aqueous-organic biphasic system with copper-mediated initiators for continuous activator regeneration is successfully developed for atom transfer radical polymerization (ICAR ATRP) (termed DRPTC-based ICAR ATRP here), using methyl methacrylate (MMA) as a model monomer, ethyl α-bromophenylacetate (EBrPA) as an initiator, and tris(2-pyridylmethyl)amine (TPMA) as a ligand. In this system, the monomer and initiating species in toluene (organic phase) and the catalyst complexes in water (aqueous phase) are simply mixed under stirring at room temperature. The trace catalyst complexes transfer into the organic phase via diffusion to trigger ICAR ATRP of MMA with ppm level catalyst content once the system is heated to the polymerization temperature (75 °C). It is found that well-defined PMMA with controlled molecular weights and narrow molecular weight distributions can be obtained easily. Furthermore, the polymerization can be conducted in the presence of limited amounts of air without using tedious degassed procedures. After cooling to room temperature, the upper organic phase is decanted and the lower aqueous phase is reused for another 10 recycling turnovers with ultra low loss of catalyst and ligand loading. At the same time, all the recycled catalyst complexes retain nearly perfect catalytic activity and controllability, indicating a facile and economical strategy for catalyst removal and recycling.

Developing a highly efficient and facile method for catalyst separation and recycling from an ATRP system facilitates wide application of atom transfer radical polymerization (ATRP). In this work, an important development of thermoregulated phase transfer catalysis (TRPTC)-based initiators for continuous activator regeneration (ICAR) ATRP for transition metal catalyst separation and recycling in a water/p-xylene biphasic system was achieved using alkyl halide (ethyl-2-bromo-2-phenyl acetate, EBPA) as the initiator for the first time. Herein, poly(poly(ethylene glycol) methyl ether methacrylate)-supported dipicolylamine (PPEGMA-BPMA) was designed as the thermoregulated ligand, CuBr2 as the catalyst, 1,1′-azobis(cyclohexanecarbonitrile) (ACHN) as the azo-initiator and methyl methacrylate (MMA) as the model monomer, respectively. The polymerization kinetics was investigated in detail, and the “living” feature of this novel polymerization system was confirmed by chain-end analysis and chain extension experiments for the resultant PMMA. It is noted that the catalyst complex (PPEGMA-BPMA/CuBr2) existed only in an aqueous phase at room temperature, and it transferred to an organic phase and subsequently catalyzed the ICAR ATRP of MMA when the temperature increased to 90 °C. After polymerization the catalyst complex successfully transferred to the aqueous phase almost completely from the organic phase again while the resultant PMMA existed in the p-xylene phase once the temperature cooled down to room temperature. Therefore, the process described above combined the advantages of homogeneous catalysis in the organic phase and heterogeneous catalyst separation in situ in the aqueous/organic biphasic phase system by just changing the reaction temperature. Importantly, the catalyst complex in the aqueous phase could be recycled easily, and the catalyst retained high catalytic activity even after eight recycling times.

Iron catalysts are attractive catalysts for atom transfer radical polymerization (ATRP) owing to their abundancy, low toxicity and good biocompatibility. However, the recycling of iron catalysts is still a great challenge although the recycling of copper catalysts has achieved success. In this work, we develop a facile and highly efficient separation and recycling strategy for an iron catalyst combining thermoregulated phase separable catalysis (TPSC) and initiators for continuous activator regeneration for atom transfer radical polymerization (ICAR ATRP) in a PEG-200/p-xylene biphasic system. Herein, FeCl3·6H2O was used as the catalyst, tetrabutylammonium bromide (TBABr) as the ligand, 2,2′-azobisisobutyronitrile (AIBN) as the reducing agent, ethyl-2-bromo-2-phenyl acetate (EBPA) as the initiator, and methyl methacrylate (MMA) as the model monomer. The PEG-200/p-xylene biphasic system formed a homogeneous polymerization solution at 70 °C, and the iron catalyst could be easily separated in situ just by a simple standing and decantation process, and was therefore recycled for the next polymerization when the polymerization temperature decreased to room temperature. In this novel polymerization system, well-defined PMMA with controlled molecular weights and narrow molecular weight distributions could be easily obtained, and the iron catalyst could be recycled in situ 10 times without any significant loss of the catalyst activity. In addition, this novel strategy was also extended to other hydrophobic monomers such as styrene, methyl acrylate and tert-butyl acrylate, indicating a versatile method for iron catalysis, separation and recycling.

A green and highly efficient AGET ATRP (activators generated by electron transfer for atom transfer radical polymerization) system was constructed in the absence of any additional ligands, using FeCl3·6H2O as a catalyst, and methyl methacrylate as a model monomer in polyethylene glycol 400 (PEG-400). The effects of various factors, such as the type of ATRP initiator, the molecular weight of PEG and the reducing agent type, polymerization temperature as well as solvent, on the polymerization were investigated. Polymerization kinetics demonstrated that the polymerization was a controlled/“living” process with molecular weight increasing linearly with conversion while maintaining a low molecular weight distribution. The living feature was further confirmed by chain extension experiments.

A strategy of thermo-regulated phase-separable catalysis (TPSC) is applied to the Cu(II)-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in a p-xylene/PEG-200 biphasic system. Initiators for continuous activator regeneration ATRP (ICAR ATRP) are used to establish the TPSC-based ICAR ATRP system using water-soluble TPMA as a ligand, EBPA as an initiator, CuBr2 as a catalyst, and AIBN as a reducing agent. By heating to 70 °C, unlimited miscibility of both solvents is achieved and the polymerization can be carried out under homogeneous conditions; then on cooling to 25 °C, the mixture separates into two phases again. As a result, the catalyst complex remains in the PEG-200 phase while the obtained polymers stay in the p-xylene phase. The catalyst can therefore be removed from the resultant polymers by easily separating the two different layers and can be reused again. It is important that well-defined PMMA with a controlled molecular weight and narrow molecular weight distribution could be obtained using this TPSC-based ICAR ATRP system.

An iron-mediated reverse ATRP of methyl methacrylate (MMA) is successfully carried out in water in the absence of any dispersants, using a water-soluble 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50) as the initiator and the stabilizer, and using an oil-soluble N,N-butyldithiocarbamate ferrum (Fe(S2 CN(C4 H9 )2 )3 ) as the catalyst without adding any additional ligands. Micron-sized PMMA particles with UV light-sensitive -S2 CN(C4 H9 )2 end group are obtained, and monomer droplet nucleation and suspension polymerization mechanism are proposed. Polymerization results demonstrated typical "living"/controlled characteristics of ATRP: first-order polymerization kinetics, linear increase of molecular weights with monomer conversion and narrow molecular weight distributions for the resultant PMMA particles. NMR spectroscopy and chain-extension experiments under UV light irradiation confirm the attachment and livingness of UV light-sensitive -S2 CN(C4 H9 )2 group in the chain end.

Poly(glycidyl methacrylate)-block-poly(4-vinylbenzyl chloride), or P(GMA)-b-P(VBC), is synthesized via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerizations. Subsequent functionalization via atom-transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and styrene (St) gives rise to two functional brush-type diblock graft copolymers, P(GMA)-b-(P(VBC)-g-P(MMA)) and P(GMA)-b-(P(VBC)-g-PS). These graft copolymers are further functionalized by a ring-opening reaction of the P(GMA) block with diethylamine (DEA) to produce two diblock copolymer brushes, P(DEAHPMA)-b-(P(VBC)-g-P(MMA) and P(DEAHPMA)-b-(P(VBC)-g-PS (Brush-2A). Single molecules of the copolymers are imaged by atomic force microscopy (AFM). Brush-2A can be cast into porous membranes with well-defined micropores from tetrahydrofuran (THF) solutions by phase inversion in an aqueous medium.

Porcine circovirus type 2 (PCV2) induces autophagy via the 5' adenosine monophosphate-activated protein kinase (AMPK)/extracellular signal-regulated kinase (ERK)/tuberous sclerosis complex 2 (TSC2)/mammalian target of rapamycin (mTOR) pathway in pig kidney PK-15 cells. However, the underlying mechanisms of AMPK activation in autophagy induction remain unknown. With specific inhibitors and RNA interference (RNAi), we show that PCV2 infection upregulated calcium/calmodulin-dependent protein kinase kinase-beta (CaMKKβ) by increasing cytosolic Ca(2+) via inositol 1,4,5-trisphosphate receptor (IP3R). Elevation of cytosolic calcium ion (Ca(2+)) did not seem to involve inositol 1,4,5-trisphosphate (IP3) release from phosphatidylinositol 4,5-bisphosphate (PIP2) by phosphoinositide phospholipase C-gamma (PLC-γ). CaMKKβ then activated both AMPK and calcium/calmodulin-dependent protein kinase I (CaMKI). PCV2 employed CaMKI and Trp-Asp (WD) repeat domain phosphoinositide-interacting protein 1 (WIPI1) as another pathway additional to AMPK signaling in autophagy initiation. Our findings could help better understanding of the signaling pathways of autophagy induction as part of PCV2 pathogenesis. Further research is warranted to study if PCV2 interacts directly with IP3R or indirectly with the molecules that antagonize IP3R activity responsible for increased cytosolic Ca(2+) both in PK-15 cells and PCV2-targeted primary cells from pigs.

Streptococcus suis is one of the common pathogens causing diseases in pigs and covers 35 serotypes with the type 2 strains being more pathogenic and zoonotic. Existing inactivated or subunit vaccines, in clinical use or under trial, could not provide cross protection against other serotypes. We identified a natural low-virulence S. suis type 5 strain XS045 as a live vaccine candidate because it is highly adhesive to the cultured HEp-2 cells, but with no apparent pathogenicity in mice and piglets. We further demonstrate that subcutaneous administration of the live XS045 strain to mice induced high antibody responses and was able to provide cross protection against challenges by a type 2 strain HA9801 (100% protection) and a type 9 strain JX13 (85% protection). Induction of high-titer antibodies with opsonizing activity as well as their cross-reactivity to surface proteins of the types 2 and 9 strains and anti-adhesion effect could be the mechanisms of cross protection. This is the first report that a live vaccine candidate S. suis type 5 strain could induce cross-protection against strains of types 2 and 9. This candidate strain is to be further examined for safety in pigs of different ages and breeds as well as for its protection against other serotypes or other strains of the type 2, a serotype of particular importance from public health concern.

Methyl methacrylate (MMA) were successfully polymerized by atom transfer radical polymerization with activator generated by electron transfer (AGET ATRP) using copper or iron wire as the reducing agent at 90°C. Well-controlled polymerizations were demonstrated using an oxidatively stable iron(III) chloride hexahydrate (FeCl3·6H2O) as the catalyst, ethyl 2-bromoisobutyrate (EBiB) as the initiator, and tetrabutylammonium bromide (TBABr) or triphenylphosphine as the ligand. The polymerization rate was fast and affected by the amount of catalyst and type of reducing agents. For example, the polymerization rate of bulk AGET ATRP with a molar ratio of [MMA]0/[EBiB]0/[FeCl3·6H2O]0/[TBABr]0 = 500/1/0.5/1 using iron wire (the conversion reaches up to 82.2% after 80 min) as the reducing agent was faster than that using copper wire (the conversion reaches up to 86.1% after 3 h). At the same time, the experimental Mn values of the obtained poly(methyl methacrylate) were consistent with the corresponding theoretical ones, and the Mw/Mn values were narrow (∼1.3), showing the typical features of “living”/controlled radical polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Atom Transfer Radical Polymerization (ATRP) is an important polymerization process in polymer synthesis. However, a typical ATRP system has some drawbacks. For example, it needs a large amount of transition metal catalyst, and it is difficult or expensive to remove the metal catalyst residue in products. In order to reduce the amount of catalyst and considering good biocompatibility and low toxicity of the iron catalyst, in this work, we developed a homogeneous polymerization system of initiators for continuous activator regeneration ATRP (ICAR ATRP) with just a ppm level of iron catalyst. Herein, we used oil-soluble iron (III) acetylacetonate (Fe(acac)3) as the organometallic catalyst, 1,1′-azobis (cyclohexanecarbonitrile) (ACHN) with longer half-life period as the thermal initiator, ethyl 2-bromophenylacetate (EBPA) as the initiator, triphenylphosphine (PPh3) as the ligand, toluene as the solvent and methyl methacrylate (MMA) as the model monomer. The factors related with the polymerization system, such as concentration of Fe(acac)3 and ACHN and polymerization kinetics, were investigated in detail at 90 °C. It was found that a polymer with an acceptable molecular weight distribution (Mw/Mn = 1.43 at 45.9% of monomer conversion) could be obtained even with 1 ppm of Fe(acac)3, making it needless to remove the residual metal in the resultant polymers, which makes such an ICAR ATRP process much more industrially attractive. The “living” features of this polymerization system were further confirmed by chain-extension experiment.

In this paper, we analyzed a delayed stage-structured predator-prey model with impulsive stocking on prey and continuous harvesting on predator. Sufficient conditions for the global attractivity of 'predator-eradication' periodic solution and permanence of the system are obtained. The results show that the behavior of impulsive stocking on prey plays an important role for the permanence of the system.

In this paper, an SIR epidemic model is constructed and analyzed. We get the result that if the parameters satisfy the condition @b>@a+@c+b, then the disease will be ultimately permanent. Under this condition, we consider how the impulsive vaccination affects the original system. The sufficient condition for the global asymptotical stability of the disease-eradication solution is obtained. We also get that if the impulsive vaccination rate is less than some value, the disease will be permanent, and the disease cannot be controlled. People can select appropriate vaccination rate according to our theoretical result to control diseases.

In this paper, a predator–prey model with disease in the prey is constructed and investigated for the purpose of integrated pest management. In the first part of the main results, the sufficient condition for the global stability of the susceptible pest-eradication periodic solution is obtained, which means if the release amount of infective prey and predator satisfy the condition, then the pest will be controlled. The sufficient condition for the permanence of the system is also obtained subsequently, which means if the release amount of infective prey and predator satisfy the condition, then the prey and the predator will coexist. At last, we interpret our mathematical results.

A new matrix Lie algebra and its corresponding Loop algebra are constructed firstly, as its application, the multi-component NLS-MKdV equation hierarchy is obtained, then by use of trace identity the Hamiltonian structure of the above system is presented. Finally, the integrable couplings of the obtained system is worked out by the expanding matrix Loop algebra.

A delay differential mathematical model that described HIV infection of CD4+ T-cells is analyzed. The stability of the non-negative equilibria and the existence of Hopf bifurcation are investigated. A stability switch in the system due to variation of delay parameter has been observed, so is the phenomena of Hopf bifurcation and stable limit cycle. The estimation of the length of delay to preserve stability has been calculated. Using the normal form theory and center manifold argument, the explicit formulaes which determine the stability, the direction and the periodic of bifurcating period solutions are derived. Numerical simulations are carried out to explain the mathematical conclusions.

A novel photo-induced homogeneous atom transfer radical polymerization (ATRP) system is constructed using an organic copper salt (Cu(SC(S)N(C2 H5 )2 )2 ) as a photo-induced catalyst at 30 °C. Herein, N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) is used as a ligand, ethyl 2-bromophenylacetate (EBPA) as an ATRP initiator, and (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO) as a photo-induced radical initiator to establish an ICAR (initiators for continuous activator regeneration) ATRP using methyl methacrylate (MMA) as a modal monomer. The effect of the concentration of the organic copper on the polymerization is investigated in detail. It is found that well-controlled polymerization can be obtained even with the amount of (Cu(SC(S)N(C2 H5 )2 )2 decreasing to a 1.56 ppm level, with the molecular weight of the resultant polymers increasing linearly with monomer conversion while maintaining a narrow molecular weight distribution (M¯w/M¯n < 1.3).

A facile homogeneous polymerization system involving the iniferter agent 1-cyano-1-methylethyl diethyldithiocarbamate (MANDC) and copper(II) acetate (Cu(OAc)2 ) is successfully developed in bulk using methyl methacylate (MMA) as a model monomer. The detailed polymerization kinetics with different molar ratios (e.g., [MMA]0 /[MANDC]0 /[Cu(OAc)2 ]0 = 500/1/x (x = 0.1, 0.2, 0.5, 1.0)) demonstrate that this system has the typical "living"/controlled features of "living" radical polymerization, even with ppm level catalyst Cu(OAc)2 , first order polymerization kinetics, a linear increase in molecular weight with monomer conversion and narrow molecular weight distributions for the resultant PMMA. (1) H NMR spectra and chain-extension experiments further confirm the "living" characteristics of this process. A plausible mechanism is discussed.

In this work, bifunctional nanoparticles (NPs) capable of emitting near infrared (NIR) fluorescence and generating superparamagnetism under an external magnetic field were prepared by combination of 'click' reaction and surface-initiated activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) of water-soluble poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) and glycidyl methacrylate (GMA) using biocompatible iron as the catalyst on the surface of silica-coated iron oxide (Fe3O4@SiO2) NPs. The nanosized Fe3O4@SiO2@PPEGMA-co-PGMA@N3 was prepared through AGET ATRP and alkynyl bearing NIR dye was also prepared; afterwards they were integrated together by 'click' reaction. The different stages of surface modification were approved by employing different characterization techniques such as TEM, XRD, XPS, VSM and FT-IR, and the properties of the final NPs were thoroughly studied. Their suitability as dual model imaging agents for magnetic resonance (MR) and fluorescence imaging was investigated, indicating them to be a competitive candidate for imaging contrast agents.

A new series of tetrahydrocarbolines with potent MCH-1 antagonist activity were synthesized, using a conformationally constrained design approach towards optimizing pharmacokinetic properties. Two compounds from this series were progressed to a 5-day diet-induced obesity mouse screening model to evaluate their potential as weight loss agents. Both compounds produced a highly significant reduction in weight, which was attributed to their improved pharmacokinetic profile.