Search

Xanthobacter flavus DT8, a direct metabolizer, degraded 1,4-dioxane without a lag phase when pregrown in R2A medium or with 1,4-dioxane. This finding implies the involvement of constitutive enzymes in the degradation and the feasibility of large-scale cell cultivation. Based on Haldane's growth model, a maximum specific growth rate of 0.15 h−1 was obtained, which is the highest value reported in the literature. However, the maximum specific degradation rate by X. flavus DT8 was lower than that by Pseudonocardia dioxanivorans CB1190, which could be due to their different cell yields. 1,4-Dioxene, ethylene glycol, and oxalic acid were identified as the main intermediates of 1,4-dioxane degradation through GC–MS analysis. Acetylene and metyrapone did not affect 1,4-dioxane degradation, which indicates that cytochrome P450s were not involved in the process. X. flavus DT8 could also metabolically degrade other cyclic ethers, including 1,3-dioxane and tetrahydrofuran (THF). Despite the presence of competitive inhibition, the average 1,4-dioxane removal rate could be enhanced by THF.

Pseudomonas putida S-1 was isolated from activated sludge. This novel strain was capable of degrading malodorous 1-propanethiol (PT). PT degradation commenced with no lag phase by cells pre-grown in nutrition-rich media, such as Luria-Bertani (LB), and PT-contained mineral medium at specific growth rates of 0.10-0.19 h(-1); this phenomenon indicated the operability of a large-scale cell culture. A possible PT degradation pathway was proposed on the basis of the detected metabolites, including dipropyl disulfide, 3-hexanone, 2-hexanone, 3-hexanol, 2-hexanol, S(0), SO4(2-), and CO2. P. putida S-1 could degrade mixed pollutants containing PT, diethyl disulfide, isopropyl alcohol, and acetaldehyde, and LB-pre-cultured cells underwent diauxic growth. Waste gas contaminated with 200-400 mg/m(3) PT was continuously treated by P. putida S-1 pre-cultured in LB medium in a completely stirred tank reactor. The removal efficiencies exceeded 88% when PT stream was mixed with 200 mg/m(3) isopropanol; by contrast, the removal efficiencies decreased to 60% as the empty bed residence time was shortened from 40 s to 20 s.

Owing to the strong solid-state luminescence of aggregation-induced emission luminogen (AIEgen), polymer/AIEgen nanoparticles (NPs) have great potential in application as high-quality luminescent inks. In this work, polymer/AIEgen NPs with a particle size below 70 nm were efficiently prepared through encapsulation of AIEgens with various colors within polymeric matrix via miniemulsion polymerization. The prepared polymer/AIEgen NPs emitted bright and stable blue, green, or orange-red fluorescence. The polymer/AIEgen NP inks suitable for inkjet printing were conveniently made through addition of a non-ionic surfactant to the emulsions with corresponding polymer/AIEgen NPs. The bright, high-resolution, and UV-responsive images were printed on cotton textiles with polymer/AIEgen NP inks. The microscopic observation indicated that the polymer/AIEgen NPs could form homogenous films onto the cotton fibers. More promisingly, the prepared polymer/AIEgen NPs with various colors had good compatibility, and they could be directly mixed to prepare multicolor polymer/AIEgen NP inks for handwriting.

The first step of microbial biodegradation is the adsorption of pollutants on the microorganisms' surface, which is determined by the microorganism type and pollutant hydrophobicity. One fungus Ophiostoma stenoceras LLC and one bacterium Pseudomonas veronii ZW were chosen for the investigation of cell surface hydrophobicity and adsorption abilities to various organic compounds. Results showed that the fungus could better capture and adsorb organic compounds in liquid and gas phases, and the adsorption was a physical monolayer adsorption process. Much smaller partition coefficient for gas-fungus suggested that direct gaseous adsorption was preferred. The XPS (X-ray photoelectron spectroscopy) characterization further confirmed that several functional groups changed after the adsorption of compounds. The time taken for complete degradation of hexane, tetrahydrofuran and chlorobenzene was shorter with the addition of O. stenoceras LLC. Such findings are useful in exploring the special cell surface of fungus in adsorption and bioenhancement for organic treatment of organic contaminants using bacteria.

The type of packing material for biofiltration has a great impact on microbial growth and pollutant removal. This study evaluated the feasibility of a nutritional slow-release packing material with functional microorganisms (NSRP-FM) in a biofilter for the removal of gaseous n-butyl acetate. Through the emulsification-cross linked process and microbial immobilization, an innovative packing material was obtained, with a specific surface area of 2.45 m2 g−1 and a bulk density of 40.75 kg m-3. The cumulative release rates of total phosphorus and total nitrogen were 90.6% and 75.6%, respectively, as measured while continuously spraying deionized water. To evaluate the performance of biofiltration, NSRP-FM was compared with the commercial polyurethane foam (PU-foam), in two identical biotrickling filters (BTFs). The BTF packed with the prepared NSRP-FM maintained a consistent removal efficiency (over 95%) without nutrients addition and pH adjustment. The other BTF had poor removal performance, and the removal efficiency declined to 65% when there was no pH adjustment. Energy dispersive X-ray spectroscopy (EDS) analysis of NSRP-FM showed that inorganic elements were released during the operation of BTF. The abundance of functional microorganisms suggested that the prepared NSRP-FM provided a better environment for microbial growth, despite changes in the operating conditions.

In this paper, the problem of estimation of radar target scattering center is estimated by VBGS (Variational Bayesian Block Sparse) algorithm, the signal representation model of radar is analyzed and the complete dictionary is constructed. Secondly, the iterative process of VBGS algorithm is introduced and the two-dimensional scattering center is obtained by sparse parameter estimation. The algorithm does not need to set user parameters and has anti noise performance. The simulation results show that the VBGS algorithm has the exact estimation effect and verifies the effectiveness of the algorithm.

Ultraviolet (UV) shielding, superhydrophobic and antimicrobial cotton fabrics were fabricated using functional coatings combined with advantages of polyvinylsilsesquioxane and ZnO nanoparticles by solution immersion. The influence of composite coatings on surface morphology, water-repellence, UV shielding property, mechanical property, thermal degradation behavior and antibacterial property of the cotton fabrics was investigated respectively. It is evidently found that the cotton fabrics functionalized by composite coatings exhibited excellent UV shielding, durable superhydrophobic and antimicrobial properties as compared to the reference materials. Most notably, the mechanical properties of cotton fabrics was significantly improved by surface treatment of the composite coatings without compromising their thermal stability as compared to the pristine cotton fabric. This strategy for fabricating UV shielding and superhydrophobic cotton fabrics will guide for developing advanced functional textile in the future work, which will likely be found in many applications such as advanced protective textiles, oil/water separation, water-proof, antibacterial and self-cleaning fields.

A series of novel hydrophobic cotton fabrics with polyvinylsilsesquioxane (PVS) polymer functional coatings were successfully prepared by solution immersion. The influence of the added amount of PVS polymer on the morphology, resistance to thermal and thermooxidative degradation, and hydrophobic properties of the treated cotton fabrics was studied by attenuated total reflection infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and water contact angle measurements, respectively. The experimental results show that the PVS polymer formed a protective film on the surface of the cotton fibers; the resistance to thermal and thermooxidative degradation, and the water-repellent properties of the novel cotton fabrics were also improved with increasing added amount of PVS polymer, compared with that of reference material. The enhancement in the thermal properties of the treated cotton fabrics can likely be attributed to synergistic carbonization between the PVS protective layer and the cellulose fibers during thermal degradation. Meanwhile, it was also found that, with increasing added amount of PVS polymer, the hydrophobicity of the treated cotton fabrics was greatly improved. The noticeable improvement in the hydrophobicity of the treated cotton fabrics is ascribed to the combination of low-surface-energy PVS film and the intrinsically rough surface of the woven cotton fabrics. This strategy for fabricating novel cellulose fabrics provides a guide for the development of high-performance functional cellulose fabrics with tunable properties in the textile industry.

A series of novel addition cured polydimethylsiloxane (PDMS) composites with a given weight amount of nano-silica sol were prepared using MQ silicone resin as reinforcing agent by hydrosilylation for the first time. Influences of the used amount of MQ silicone resin on morphology, thermal stability, mechanical and optical properties of these novel PDMS composites were mainly studied. It was found that thermal stabilities and transparencies of the novel PDMS composites with a given amount of nano-silica sol decreased with an increment in weight fraction of MQ silicone resin, as compared with that of PDMS composites without MQ silicone resin (SMQ-0), which were likely ascribed to an increasing amount of remained silanols and the increasing size of aggregated particles in PDMS composites, respectively. However, mechanical properties of the novel PDMS composites with a given weight of nano-silica sol were improved significantly with amount of MQ silicone resin increasing, especially their elongations at break, which were up to 10 times. This was a great breakthrough for PDMS composites. The prominent improvements in mechanical properties were probably attributed to strong interaction of PDMS chains and uniformly dispersed particles resulted from crosslink of MQ silicone resin and nano-silca sol. This strategy for preparing novel addition curing PDMS composites provides a guide method to develop high elastic PDMS composites with desirable properties in industry applications.

In this paper, functionalized montmorillonite is intercalated with cetyl trimethyl ammonium chloride and (3-aminopropyl)triethoxysilane. Quaternized polysulfone/functionalized montmorillonite nanocomposite membranes are fabricated to evaluate their potential in anion-exchange membrane fuel cells. Fourier transform infrared spectroscopy, thermogravimetric analyzer and X-ray diffractometer are used to confirm the success of intercalation. The performances of the composite membranes for the anion-exchange membrane fuel cells in terms of their water uptake, mechanical property and ionic conductivity are investigated. Compared with other anion-exchange membranes, the nanocomposite membrane containing 5% montmorillonite modified by cetyl trimethyl ammonium chloride exhibits lower water uptake, higher ultimate stress and larger ionic conductivity. It exhibits an ionic conductivity of 4.73 × 10 −2 S cm −1 at 95 °C.

A series of novel polydimethylsiloxane (PDMS) composites were prepared using polyvinylsilsesquioxanes (PVS) as reinforcing agent by hydrolytic condensation in the presence of organotin catalyst for the first time. The cross-linked network, morphology, thermal behavior and mechanical properties of these novel PDMS composites were examined by attenuated total reflection infrared spectroscopy (ATR-IR), scanning electron microscope (SEM), thermogravimetric analysis (TGA) and universal tensile testing machine, respectively. Experimental results showed that both thermal and mechanical properties of the PDMS composites were improved greatly by adding PVS. The prominent improvements in thermal and mechanical properties were likely attributed to the reinforcing interaction of PDMS chains and formed particles resulted from PVS self-crosslink. Meanwhile, we also found that with the increment in loading PVS, the resistance to thermal degradation of the PDMS composites in nitrogen atmosphere was enhanced obviously, but their resistance to thermal oxidation in air was not improved apparently. The unobvious improvement in resistance to thermal oxidation of the novel composites was likely due to the catalysis of oxygen.

Hydrogels composed of natural materials exhibit great application potential in artificial scaffolds for cartilage repair as they can resemble the extracellular matrices of cartilage tissues comprised of various glycosaminoglycan and collagen. Herein, the natural polymers with vinyl groups, i.e. maleilated chitosan (MCS) and methacrylated silk fibroin (MSF) micro/nanoparticles, were firstly synthesized. The chemical structures of MCS and MSF micro/nanoparticles were investigated using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then MCS/MSF micro/nanocomposite hydrogels were prepared by the photocrosslinking of MCS and MSF micro/nanoparticles in aqueous solutions in the presence of the photoinitiator Darocur 2959 under UV light irradiation. A series of properties of the MCS/MSF micro/nanocomposite hydrogels including rheological property, equilibrium swelling, sol content, compressive modulus, and morphology were examined. The results showed that these behaviors could be tunable via the control of MSF content. When the MSF content was 0.1%, the hydrogel had the compressive modulus of 0.32±0.07MPa, which was in the range of that of articular cartilage. The in vitro cytotoxic evaluation and cell culture of the micro/nanocomposite hydrogels in combination with mouse articular chondrocytes were also investigated. The results demonstrated that the micro/nanocomposite hydrogels with TGF-β1 was biocompatible to mouse articular chondrocytes and could support cells attachment well, indicating their potential as tissue engineering scaffolds for cartilage repair.

Photocrosslinkable water-soluble maleilated chitosan and methacrylated poly (vinyl alcohol) were synthesized and therefore maleilated chitosan/methacrylated poly (vinyl alcohol) (MCS/MPVA) hydrogels were prepared under UV radiation. Series of properties of the hydrogels including rheological property, swelling behavior, morphology and mechanical test were investigated. The main results showed that the MCS/MPVA hydrogels had fast gel-forming rate (complete transformation to gel within 150s), improved compressive strength at 0.169±0.011MPa and rapid absorbent capacity. These behaviors could be tunable via the control of weight ratio of MCS to MPVA. The indirect cytotoxicity assessments demonstrated the photocrosslinked hydrogels was compatible to mouse fibroblasts (L929 cells), indicating their potential as tissue engineering scaffolds.

The presence of nicotine and nicotinic acid (NA) in the marine environment has caused great harm to human health and the natural environment. Therefore, there is an urgent need to use efficient and economical methods to remove such pollutants from the environment. In this study, a nicotine and NA-degrading bacterium—strain JQ581—was isolated from sediment from the East China Sea and identified as a member of Pseudomonas putida based on morphology, physio-biochemical characteristics, and 16S rDNA gene analysis. The relationship between growth and nicotine/NA degradation suggested that strain JQ581 was a good candidate for applications in the bioaugmentation treatment of nicotine/NA contamination. The degradation intermediates of nicotine are pseudooxynicotine (PN) and 3-succinoyl-pyridine (SP) based on UV, high performance liquid chromatography, and liquid chromatography-mass spectrometry analyses. However, 6-hydroxy-3-succinoyl-pyridine (HSP) was not detected. NA degradation intermediates were identified as 6-hydroxynicotinic acid (6HNA). The whole genome of strain JQ581 was sequenced and analyzed. Genome sequence analysis revealed that strain JQ581 contained the gene clusters for nicotine and NA degradation. This is the first report where a marine-derived Pseudomonas strain had the ability to degrade nicotine and NA simultaneously.

A Pseudomonas sp. strain WL2 that is able to efficiently metabolize ethyl mercaptan (EM) into diethyl disulfide (DEDS) through enzymatic oxidation was isolated from the activated sludge of a pharmaceutical wastewater plant. One hundred percent removal of 113.5 mg L−1 EM and 110.3 mg L−1 DEDS were obtained within 14 and 32 h, respectively. A putative EM degradation pathway that involved the catabolism via DEDS was proposed, which indicated DEDS were further mineralized into carbon dioxide (CO2), bacterial cells, and sulfate (SO4 2−) through the transformation of element sulfur and ethyl aldehyde. Degradation kinetics for EM and DEDS with different initial concentrations by strain WL2 were evaluated using Haldane-Andrews model with maximum specific degradation rates of 3.13 and 1.33 g g−1 h−1, respectively, and maximum degradation rate constants of 0.522 and 0.175 h−1 using pseudo-first-order kinetic model were obtained. Results obtained that aerobic degradation of EM by strain WL2 was more efficient than those from previous studies. Substrate range studies of strain WL2 demonstrated its ability to degrade several mercaptans, disulfides, aldehydes, and methanol. All the results obtained highlight the potential of strain WL2 for the use in the biodegradation of volatile organic sulfur compounds (VOSCs).

The existence of association between the subpopulation of iNKT cells with different functions and nonalcoholic fatty liver disease has not been confirmed. To investigative the role of iNKT cells in the pathogenesis of nonalcoholic fatty liver disease, we established a non-alcoholic fatty liver model by feeding C57BL/6J mice for 12 weeks with a high-fat diet and injecting α-GalCer through different routes to activate hepatic iNKT cells. The liver of the mice fed a high-fat diet (HFD) had severe hepatic steatosis appearance, elevated pro-inflammatory cytokines and reduced anti-inflammatory cytokines in the liver, and high serum levels of TC, LDL, HDL, and ALT. Our results showed that the percentage of iNKT cells in the liver of the HFD-fed mice was lower than that of the control mice. The expression levels of the related transcription factor of T-bet increased but that of GATA-3 decreased in the HFD-fed mice. The administration of α-GalCer by intraperitoneal injection resulted in increasing of hepatic iNKT and iNKT2 cells but decreasing of hepatic iNKT1 cells, and the expression of GATA-3 and anti-inflammatory cytokine (IL-4) was increased in the liver, and hepatic steatosis was ameliorated in the HFD-fed mice. The administration of α-GalCer by subcutaneous injection resulted in a decrease in hepatic iNKT and iNKT2 and an augmentation of hepatic iNKT1 cells. However, hepatic steatosis was not significantly improved. We concluded that the intraperitoneal injection with α-GalCer effectively improved hepatic steatosis, according to increasing the number of hepatic iNKT2 cells. The precise mechanism requires further exploration.

This study was designed to confirm the effect of the novel immunostimulators CH1b and CH2b with a thiazolidin-4-one ring on the function of macrophages. We used these two molecules to stimulate LPS-activated RAW 264.7 macrophages in vitro. After a series of essential assays, we found that CH1b and CH2b could significantly increase the production of nitric oxide (NO) by the LPS-activated RAW 264.7 macrophages, and also found that CH2b could more significantly increase the proliferation, phagocytic activity, and secretion of IL-6, IL-8 and TNF-α by LPS-activated RAW 264.7 cells more than CH1b. Furthermore, CH2b could increase the degradation of IκB-α and could promote the nuclear translocation of nuclear factor (NF)-κB p65 in LPS-activated RAW 264.7 cells. However, CH2b could also increase the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK). Taken together, we got that CH2b could further increase the LPS-induced activation of NF-κB and p38 MAPK in RAW 264.7 macrophages to elevate the function of macrophages, including iNOS expression, NO production, cytokines secretion, and phagocytosis.

A series of novel PDMS composites filled with a given amount of fumed silica were first prepared using divinyl-hexa[(trimethoxysilyl)ethyl]-POSS as cross-linker by hydrolytic condensation in the presence of organotin catalyst. The crosslinking reaction, the morphology, thermal behaviors and mechanical properties of the novel PDMS composites were characterized by attenuated total reflection infrared spectroscopy, scanning electron microscope, thermogravimetric analysis and universal tensile testing machine, respectively. It was found that the resistances to thermal degradation, thermo-oxidative decomposition of the novel PDMS composites were greatly improved by incorporation of POSS cross-linker, compared with that of the reference material (MT-1). Meanwhile, we also found that their thermal properties and mechanical properties were gradually enhanced with the further increment in loading amount of POSS cross-linker. The pronounced enhancements in thermal properties and mechanical properties of novel PDMS composites were likely attributed to the increasing interaction of PDMS chains and aggregated particles from synergistic effect between POSS and fumed silica.

An effective dichloromethane (DCM) utilizer Methylobacterium rhodesianum H13 was isolated from activated sludge. A response surface methodology was conducted, and the optimal conditions were found to be 4.5 g/L Na2HPO4·12H2O, 0.5 g/L (NH4)2SO4, an initial pH of 7.55, and a temperature of 33.7 °C. The specific growth rate of 0.25 h(-1) on 10 mM DCM was achieved, demonstrating that M. rhodesianum H13 was superior to the other microorganisms in previous investigations of DCM utilization. DCM mineralization paralleled the production of cells, CO2, and water-soluble metabolites, as well as the release of Cl(-), whereas the carbon distribution and Cl(-) yield varied with DCM concentrations. The facts that complete degradation only occurred with DCM concentrations below 15 mM and repetitive degradation of 5 mM DCM could proceed for only three cycles were ascribed to pH decrease (from 7.55 to 3.02) though a buffer system was employed.

A series of novel polydimethylsiloxane (PDMS) composites were prepared using octa[(trimethoxysilyl)ethyl]-POSS (OPS) as cross-linker and fumed silica as reinforcing filler. The cross-linked networks, morphologies, thermal and mechanical properties of these novel PDMS composites were examined by attenuated total reflection infrared spectroscopy and the extraction/swelling experiment, scanning electron microscope, thermogravimetric analysis, and universal tensile testing machine, respectively. It was found that both the resistance to thermal degradation and mechanical properties of the novel PDMS composites were improved greatly by adding fumed silica. The prominent improvements in resistance to thermal degradation and mechanical properties of novel PDMS composites were likely attributed to the enhanced interaction of PDMS chains and aggregated particles resulted from synergistic effect between POSS and fumed silica. Meanwhile, we also found that the resistance to thermal degradation of the PDMS composites was lowered slightly with the further increment in loading fumed silica, but their mechanical properties were enhanced. The slight decrease in trend of the resistance to thermal degradation of the novel PDMS composites was likely ascribed to the increasing amount of hydroxyl groups resulting from fumed silica. And the improving mechanical properties were mainly attributed to the increasing interaction of PDMS chains and aggregated particles originated from synergistic effect between POSS and fumed silica. POLYM. COMPOS., 34:1041–1050, 2013. © 2013 Society of Plastics Engineers

A novel cross-linker (denoted as PH) prepared using vinyl-POSS and poly(methylhydrogensiloxane) (PMHS), was introduced to vinyl terminated polydimethylsiloxane (VPDMS) matrix to prepare a series of addition-type silicone rubbers (ASR) for the first time. Morphology, thermal properties and mechanical properties of these ASR were respectively studied by means of scanning electron microscope (SEM), thermal gravimetric analysis (TGA) and universal tensile testing machine. The results revealed that the thermal stabilities and mechanical properties of ASR were significantly enhanced by the addition of PH compared with the traditional cross-linker PMHS. It was found that the tensile strength of ASR prepared using PH as cross-linker was strikingly increased by 43.8% compared with the one prepared using PMHS as cross-linker. The striking enhancements in thermal properties and improvements on mechanical properties of ASR were likely attributed to the increase of dimensionality of novel cross-linked networks in novel ASR.

To study the effect of side chains on the dispersing properties of polycarboxylate-type superplasticisers (PCs) in cement pastes, PCs with different side chains were synthesised and used as a superplasticiser for cement suspensions. The effect of side chains of PC on the zeta potential, adsorption, fluidity of the corresponding cement suspensions was investigated systematically, and total interparticle potential energy between particles was calculated. The results show that the higher the short side chains ratio of PC, the larger the adsorption amount of PC. PC with both short and long side chains presents a better dispersing property than PC with short side chains, while PC with long side chains falls in between. The maintaining dispersing ability of PC for cement particles increases as the short side chains ratio increases. The changing rule of total interparticle potential energy produced by PC is in accordance with the changing rule of dispersing property of PC in cement pastes. This indicates that the calculated results of total interparticle potential energy further support the explanation of dispersing property difference of PC in theory. This paper uses the sum of electrostatic energy and steric hindrance potential as the total interparticle potential energy to evaluate the dispersing property of PC for the first time, which is meaningful for the evaluation of dispersing property of polymer dispersant adsorbed on particle surfaces.

Invariant natural killer T cells (iNKTs) are important innate immune cells which get involved in various immune responses in both mice and humans. These immune reactions range from self-tolerance to development of autoimmunity and responses to pathogens and tumor development. In this study, we aimed to explore the effects of the novel immunostimulators (CH1b and CH2b) containing thiazolidin-4-one on the functions of human invariant natural killer T cells (iNKTs). First of all, iNKTs in peripheral blood mononuclear cells were expanded with α-Galactosylceramide (α-Galcer) in vitro. Then, the highly purified iNKTs were isolated from PBMCs using magnetic cells sorting (MACS). Next, we investigated the impacts of CH1b and CH2b on proliferation, cytokines production, cytotoxicity, and the associated signaling pathways in iNKT cells. Finally, we found that CH2b could significantly promote the activated iNKTs proliferation, increase the production of Th2 cytokines, and induce Th0 differentiation into Th2 subset via GATA 3 signaling pathway. Besides, CH2b could markedly enhance the cytotoxic ability of the activated iNKTs. Therefore, we concluded that CH2b, a promising candidate immunostimulator, might be used for the treatment of infections, tumors, autoimmune and allergic diseases, and for the correction of Th1/Th2 balance disorders in future.

In this paper, both divinyl-hexa[(trimethoxysilyl)ethyl]-POSS (DVPS) and fumed silica were firstly introduced into polydimethylsiloxane (PDMS) system using as the cross-linker and the reinforcing filler respectively. And a series of novel RTV silicone rubbers synergistically enhanced by DVPS and fumed silica were prepared. The cross-linked networks in the novel RTV silicone rubbers have been studied by attenuated total reflection infrared spectroscopy, and the dispersions of POSS and fumed silica in these novel RTV silicone rubbers have been observed by means of scanning electron microscope (SEM). And thermal stabilities, thermo-oxidative stabilities and mechanical properties of these novel RTV silicone rubbers were studied by means of thermal gravimetric analysis and universal tensile testing machine, respectively. From the obtained results, it was found that synergistic effect between POSS-rich areas and fumed silica on thermal stability and mechanical property of RTV silicone rubber indeed existed. And the experimental results also exhibited that the thermal stabilities and mechanical properties of the novel RTV silicone rubbers were far better than those of the reference materials (DVPR and MTFR). The striking enhancements in thermal properties and improvements on mechanical properties of novel RTV silicone rubbers were likely attributed to the synergistic effect between POSS-rich domains and fumed silica. Meanwhile, it was found that the mechanical properties of RTV silicone rubbers prepared with a given amount of POSS cross-linker were enhanced with the increment of the loading amount of fumed silica.

A novel cross-linker octa[(trimethoxysilyl)ethyl]-POSS (OPS) based on a Vinyl-POSS derivative was firstly prepared via hydrosilylation chemistry. The novel POSS cross-linker was applied to hydroxyl terminated polydimethylsiloxane (HPDMS) matrix to prepare a series of novel RTV silicone rubbers. The chemical incorporation of novel POSS cross-linker into PDMS by hydrolytic condensation reaction was verified by attenuated total reflection (ATR) infrared spectroscopy. Morphology, thermal properties and mechanical properties of these novel RTV silicone rubbers have been studied by means of scanning electron microscope (SEM), thermal gravimetric analysis, universal tensile testing machine and dynamic mechanical analysis, respectively. The results displayed a pronounced enhancement effect of the novel cross-linker OPS on thermal stabilities and mechanical properties of RTV silicone rubbers as compared with the PDMS polymers prepared with tetramethoxysilane (TMOS), tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMOS) cross-linkers. Subsequently, the thermal decomposition of representative novel RTV silicone rubber in nitrogen was monitored by TGA coupled with real-time IR, and the degradation residues were also characterized by FTIR. It was found that the POSS cages were beneficial to increasing the degradation residues. The striking enhancements in thermal properties and improvements on mechanical properties could be attributable to the synergistic effect of the increasing dimensionality of cross-linking networks resulting from three-dimensional structure of OPS cross-linker, the plasticization of self-cross-linked OPS cross-linker and uniform distribution of POSS-rich domains.

Two kinds of novel POSS cross-linkers were firstly prepared via hydrosilylation of Vinyl-POSS and trimethoxysilane. And two types of novel polydimethylsiloxane (PDMS) polymer composites as RTV silicone rubbers were prepared using Vinyl-POSS derivatives as cross-linkers in the presence of organotin catalyst. To completely exhibit superiorities of two kinds of novel cross-linkers, RTV silicone rubbers prepared with two proportions of different cross-linkers were assessed. The chemical inclusion of novel POSS into PDMS networks by hydrolytic condensation reaction was verified by attenuated total reflection (ATR) infrared spectroscopy. Morphologies, thermal properties, mechanical properties and hardness of these novel RTV silicone rubbers were studied. The results exhibited significantly enhanced effects of POSS on thermal stabilities, mechanical properties and hardness as compared to the PDMS polymers prepared with the traditional tetra-functional TMOS and TEOS cross-linkers. The striking improvements in thermal properties, mechanical properties and hardness could be attributed to the synergistic effect of the increase of dimensionality of cross-linked networks in novel RTV silicone rubbers resulting from special three-dimensional structure of novel POSS cross-linkers, plasticization of self-cross-linked POSS cross-linkers and uniform distribution of POSS cross-linkers.

Methylibium petroleiphilum PM1, which is capable of degrading of methyl tert-butyl ether (MTBE), was immobilized in calcium alginate gel beads. Various applications were explored to increase the mechanical strength of these gel beads. The introduction of 0.3 mol/L calcium chloride into the crosslinking solution, 0.002 mol/L calcium chloride into the growth medium, and 0.2% polyethyleneimine (PEI) as chemical crosslinking agent increased the stability of the Ca-alginate gel beads under the operation conditions of the bioreactor. The degradation rates of MTBE by the immobilized cells in the bioreactor system operated in batch and continuous mode , respectively, were compared. A MTBE biodegradation rate of 5.79 mg/L·h was reached for over 400 h (50 batches), and the immobilized cells in the bioreactor removed >96% MTBE during 50 days of operation. Molecular analysis of the PM1 cells revealed that microbial growth occurred predominantly as microcolonies in the outer area of the beads during the first 20 days of operation. The results of this study show that a continuous-mode, fixed-bed bioreactor reactor coupled with PM1-immobilized cells is a promising technology for remediating MTBE-contaminated groundwater.

Divinyl-hexa[(trimethoxysilyl)ethyl]-POSS (DVPS) as an octavinyl-POSS derivative was first prepared. A series of novel polydimethylsiloxane (PDMS)/DVPS hybrid materials as room temperature vulcanized (RTV) silicone rubber were prepared. The chemical incorporation of novel POSS into hydroxyl-terminated PDMS system by hydrolytic condensation reaction was verified by attenuated total reflection (ATR) infrared spectroscopy. Thermal degradation, thermo-oxidative stability and mechanical properties of these novel RTV silicone rubbers were studied by means of thermogravimetric analysis and tensile testing. The results exhibited significantly enhanced effects on the thermal stabilities and mechanical properties as compared to the PDMS polymer prepared with tetraethoxysilane (TEOS). The observed improvements in thermal properties could be attributed to the effective three-dimensional network structures resulting from the structure of DVPS. The thermal decomposition of the RTV silicone rubbers in nitrogen was also monitored by TGA coupled with real-time FTIR, and the degradation residues were also characterized by FTIR. It was found that the POSS cross-linker facilitated the formation of cross-links in the degradation residues. The striking improvement in mechanical properties could be attributed to the synergistic action of the structure of three-dimensional multi-arm cross-linker (vinyl-POSS derivative), the plasticization of self-cross-linking Vinyl-POSS derivative and perfect distribution of vinyl-POSS derivative.

The adsorption of methyl tert-butyl ether by granular activated carbon was investigated. The experimental data were analyzed using the Freundlich isotherm and the Langmuir isotherm. Although equilibrium data were found to follow Freundlich isotherm model, it were fitted better by the Langmuir model with a maximum adsorption capacity of 204.1 mg/g. The kinetic data obtained at different concentrations were analyzed to predict the constant rate of adsorption using three common kinetic models: pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The pseudo-second-order model was suitable for describing the adsorption kinetics for the removal of methyl tert-butyl ether from aqueous solution onto granular activated carbon. Both the Lagergren first-order rate constant k 1 and pseudo-second-order rate constant k 2 decrease with increasing initial concentrations of methyl tert-butyl ether and the intraparticle diffusion rate constant k p shows the reverse characteristic. Analysis of sorption data using a boyd plot confirmed that external mass transfer is the main rate-limiting step at the initial stage of adsorption. Results illustrate that granular activated carbon is an effective adsorbent for methyl tert-butyl ether and also provide specific guidance into adsorption of methyl tert-butyl ether on granular activated carbon in contaminated groundwater.

The contamination of methyl tert-butyl ether (MTBE) in underground waters has become a widely concerned problem all over the world. In this study, a novel closed culture system with oxygen supplied by H2O2 was introduced for MTBE aerobic biodegradation. After 7 d, almost all MTBE was degraded by a pure culture, a member of β-Proteobacteria named as PM1, in a closed system with oxygen supply, while only 40% MTBE was degraded in one without oxygen supply. Dissolved oxygen (DO) levels of the broth in closed systems respectively with and without H2O2 were about 5-6 and 4 mg/L. Higher DO may improve the activity of monooxygemase, which is the key enzyme of metabolic pathway from MTBE to tert-butyl alcohol and finally to CO2, and may result in the increase of the degrading activity of PM1 cell. The purge and trap GC-MS result of the broth in closed systems showed that tert-butyl alcohol, isopronol and acetone were the main intermediate products.

It is a challenge to synthesize transparent polydimethylsiloxane (PDMS) materials that can completely absorb the light energy of ultraviolet (UV) A, B, and C regions. Herein, near-infrared (NIR) photoluminescent PDMS composites with hydrogen-terminated silicon nanocrystals (ncSi:H) or decyl-terminated silicon nanocrystals (ncSi-decyl) fabricated by combination of hydrosilylation and polymer encapsulation are reported. Their morphologies, optical and mechanical properties, and thermal stabilities are investigated. It is interesting to find that these PDMS composites filled with even a very small amount of ncSi:H or ncSi-decyl have unprecedented UV-blocking properties and superior thermal stabilities as compared to the PDMS reference. In particular, the ncSi-decyl/PDMS composite possesses impressive photoluminescence. Furthermore, ncSi-decyl are favorable for reinforcing the mechanical properties of the PDMS composites as compared to the PDMS reference and the ncSi:H/PDMS composite. The enhancement in the mechanical properties and thermal stabilities of these novel PL PDMS composites depends upon the creation of crosslinkable sites and entanglement interactions between the PDMS chains and the ncSi. These results suggest that potential applications for NIR photoluminescent ncSi/PDMS composites will likely be found in the fields of advanced UV-blocking textiles, cosmetics, photofluids, stretchable electronic devices, anticounterfeiting materials, biological imaging, and diagnostics.

A strategy of immobilizing room temperature ionic liquid (RTIL) in proton-exchange membranes (PEMs) is demonstrated for the first time. After synthesized by ionic exchange and extraction, RTIL is anchored to the surfaces of silica nanoparticles (SiO2-RTIL) via condensation reaction. Then composite PEMs consisting of sulfonated poly(ether ether ketone) (SPEEK) and silica with RTIL are prepared through the solution casting method. The incorporation of SiO2-RTIL markedly improves the physical properties of the composite PEMs as compared to the plain SPEEK membrane, which was probably related to the plasticization and additional proton conductivity of the SiO2-RTIL. The anhydrous proton conductivity of the resultant composite PEM with 30% SiO2-RTIL was 50 times that of the plain membrane at 150[Formula: see text]C.

The biodegradation kinetics of tetrahydrofuran, benzene (B), toluene (T), and ethylbenzene (E) were systematically investigated individually and as mixtures by a series of aerobic batch degradation experiments initiated by Pseudomonas oleovorans DT4. The Andrews model parameters, e.g., maximum specific growth rates (μmax), half saturation, and substrate inhibition constant, were obtained from single-substrate experiments. The interaction parameters in the sum kinetics model (SKIP) were obtained from the dual substrates. The μmax value of 1.01 for tetrahydrofuran indicated that cell growth using tetrahydrofuran as carbon source was faster than the growth on B (μmax, B = 0.39) or T (μmax, T = 0.39). The interactions in the dual-substrate experiments, including genhancement, inhibition, and co-metabolism, in the mixtures of tetrahydrofuran with B or T or E were identified. The degradation of the four compounds existing simultaneously could be predicted by the combination of SKIP and co-metabolism models. This study is the first to quantify the interactions between tetrahydrofuran and BTE.

To explore the immunostimulatory effect of immunostimulant CH2a bearing thiazolidin-4-one on human invariant natural killer T (iNKT) cell function in vitro.Peripheral blood mononuclear cells (PBMCs) were obtained from healthy adults, and then amplified with α-Galcer and IL-2 in vitro. The iNKT cells were isolated from these proliferating cells by magnetic-activated cell sorting (MACS) method. The purified iNKT cells were labled with 5-(and 6)-carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) and then incubated with CH2a for functional analysis, including cell proliferation, expressions of IFN-γ and IL-4 by flow cytometry, proliferation rate and cytotoxicity by MTT assay. In additon, ELISA was performed to determine the levels of IFN-γ and IL-4 in cell culture media.CH2a significantly promoted the proliferation of iNKT cells induced by IL-2 in vitro, stimulated the release of both IFN-r and IL-4, and led to the increase in IFN-γ/IL-4 ratio. More importantly, the cytotoxicity of iNKT was also markedly elevated under the stimulation of CH2a.Immunostimulant CH2a probably promote the production of Th1-like cytokines and the differentiation of Th0 to Th1, so as to improve cellular immune function. In addition, CH2a could significantly enhance the cytotoxicity of iNKT cells.

A novel entrapment matrix, calcium alginate (CA) coupled with activated carbon fiber (ACF), was prepared to immobilize Pseudomonas oleovorans DT4 for degrading tetrahydrofuran (THF). The addition of 1.5% ACF increased the adsorption capacity of the immobilized bead, thus resulting in an enhanced average removal rate of 30.3mg/(Lh). The synergism between adsorption and biodegradation was observed in the hybrid CA-ACF beads instead of in the system comprising CA beads and freely suspended ACF. The effective diffusion coefficient of the CA-ACF bead was not significantly affected by bead size, but the bead's value of 1.14×10(-6)cm(2)/s (for the bead diameter of 0.4 cm) was larger than that of the CA bead by almost one order of magnitude based on the intraparticle diffusion-reaction kinetics analysis. Continuous treatment of the THF-containing wastewater was succeeded by CA-ACF immobilized cells in a packed-bed reactor for 54 d with a >90% removal efficiency.

The preparations of natural rubber composites and nanocomposites are mainly outlined in this chapter according to classification of reinforcing agents. Up to present, the reinforcing agents have been mainly divided into four different types of nano-fillers, namely, conventional fillers, natural fillers, inorganic metal or metallic compound fillers and hybrid fillers. The natural rubber composites and nanocomposites are generally prepared by three main methods, namely, mechanical blending, solution mixing and melting blending. The thermal and mechanical properties of natural rubber composites and nanocomposites were summarized. The advantages and disadvantages of each method were discussed in detail with emphasis on the classification of reinforcing fillers.

To investigate how the novel synthetic immunostimulators (CH1a, CH2a, CH1b and CH2b) with a core substructure of thiazolidin-4-one ring influence the function of human natural killer (NK) cells in vitro, first, we obtained highly purified and viable NK cells from peripheral blood mononuclear cells (PBMCs) by a magnetic cell sorter (MACS). Then, the cytotoxicity and proliferative capacity of NK cells were explored after treatment with CH1a, CH2a, CH1b and CH2b. Moreover, the production of IFN-γ and TNF-α was also analyzed. We found that CH1b and CH2b could induce a significant enhancement of cytotoxicity and cytokine production including IFN-γ and TNF-α by NK cells. However, CH1b and CH2b could hardly promote the proliferation of NK cells. In immunoblotting analysis assay, we found that ERK 1/2 could be significantly phosphorylated after treatment with CH1b and CH2b, while the same phenomenon did not emerge after blockade with PD098059, the specific inhibitor of ERK1/2 signaling pathways. Taken together, we can conclude that CH1b and CH2b can elevate the cytotoxicity probably via ERK 1/2 activation.

Control problem is investigated for dry clutch engagement process during a standing start in AMT vehicles. Based on the control-oriented simplified driveline dynamic model under consideration of parametric uncertainties of the driveline due to the mechanical wear and tear, the elastic deformation of shaft and so on, an adaptive tracking control strategy is examined paying particular attention to the engagement comfort while not deteriorating the slipping time by using the crankshaft speed and the clutch disk speed as state variables and the engine torque and the clutch torque as control variables. The resulting analytically derived adaptive controller guarantees the fast smooth engagement of the clutch and the engine stall avoidance. Simulation results show the good performance obtained with the proposed controller.

The efficient tetrahydrofuran (THF)-degrading bacterium, Pseudomonas oleovorans DT4 was used to investigate the substrate interactions during the aerobic biotransformation of THF and BTEX mixtures. Benzene and toluene could be utilized as growth substrates by DT4, whereas cometabolism of m -xylene, p -xylene and ethylbenzene occurred with THF. In binary mixtures, THF degradation was delayed by xylene, ethylbenzene, toluene and benzene in descending order of inhibitory effects. Conversely, benzene (or toluene) degradation was greatly enhanced by THF leading to a higher degradation rate of 39.68 mg/(h g dry weight) and a shorter complete degradation time about 21 h, possibly because THF acted as an “energy generator”. Additionally, the induction experiments suggested that BTEX and THF degradation was initiated by independent and inducible enzymes. The transient intermediate hydroquinone was detected in benzene biodegradation with THF while catechol in the process without THF, suggesting that P. oleovorans DT4 possessed two distinguished benzene pathways.

A Gram-negative strain DT4, capable of growing aerobically on tetrahydrofuran (THF) as the sole carbon and energy source was isolated from a pharmaceutical wastewater treatment plant. It was identified as Pseudomonas oleovorans by morphological and physiological characteristics as well as Biolog profiling and 16S rDNA sequence. Cells of P. oleovorans DT4 pre-cultured in THF could degrade 5 mM THF completely without lag phase. The generation time of 2.7 h and the maximum degradation rate of 203.9 mg THF/(h g dry weight) were observed, demonstrating that DT4 bears the highest THF-degrading activity in ever described strains. Furthermore, THF concentration as high as 100 mM was tolerated by the culture. Several important compounds including γ-butyrrolactone and benzene could be directly metabolized, whereas other pollutants (e.g., tetrahydropyrane) could be cometabolized by DT4. THF removal was achieved in a continuous flow system with the maximum specific growth rate 0.113 h−1 and half-saturation constant 1.224 mg/L, indicating the great potential of THF bioremediation in future full-scale application.

The contamination of ground and surface water with methyl tert-butyl ether (MTBE) has evoked substantial attention due to the frequent occurrence of storage tank leakage. Kinetic analysis of MTBE degradation by polyethyleneimine stabilized beads with alginate immobilized Methylibium petroleiphilum PM1 was investigated in this paper. The results showed that the stabilized beads could be used wider in respect to pH value, temperature and initial MTBE concentration than freely-suspended cells under the same conditions. The biochemical reaction rather than intraparticle diffusion resistance was considered as the key step by the kinetic analysis.

Supplements with readily metabolizable organic substrates were investigated to increase the biomass and enhance degradation of methyl tert-butyl ether (MTBE) due to the low biomass yield of MTBE which has been one of the factors for low-rate MTBE degradation. The influence of various organic substrates on the rate of aerobic degradation of methyl tert-butyl ether (MTBE) by Methylibium petroleiphilum PM1 was investigated, and only yeast extract (YE), beef extract and tryptone exhibited stimulatory effect. With the concentration of each substrate being 100 mg/L, the average MTBE removal rate could increase to 1.29, 1.20 and 1.04 mg/(Lh), respectively, in comparison with 0.71 mg/(Lh) when carried out in medium without addition. The stimulatory effects of YE addition, as well as induction period required by MTBE degradation, varied dramatically with the storage conditions, pre-culture medium and concentrations of the inoculums. The extent of stimulatory effects of YE might be closely related to the proportion of induction period in the total time of MTBE-degradation. The removal efficiency increased from about 50% to 90.5% with the addition of YE in a packed-bed reactor loaded with calcium alginate immobilized cells.

In this study, degradation of methyl tert-butyl ether (MTBE) by resting cells of Methylibium petroleiphilum PM1 was performed in poor nutrition solution, major component of which was MTBE. It was found that the biomass was hard to increase in poor nutrition, and the MTBE degradation activity was enhanced by 4.65-fold when 1 mM of Ba(2+) was added into deionized water. It was also found that the MTBE degradation could be significantly improved by the dissolved oxygen level. All of 50 mg L(-1) MTBE could be degraded under aerobic condition, while only 5% was degraded under anaerobic condition by resting cells in poor nutrition solution after 12 h. In the above solution, the degradation of tert-butyl alcohol (TBA) was found to be faster than that of MTBE, which suggested that TBA degradation might not be the limiting step in MTBE metabolism. While in the poor nutrition solution with the mixture of MTBE and TBA, the addition of TBA did not affect MTBE degradation while MTBE inhibited TBA degradation weakly, which suggested that different and independent enzymes were responsible for degrading such compounds. The success of MTBE degradation by PM1 cells in real contaminated groundwater demonstrated its feasibility to biodegrade MTBE under poor environment, and it also indicated the great potential of MTBE bioremediation by entrapped cells in future application.

Cells of Methylibium petroleiphilum PM1 were immobilized in gel beads to degrade methyl tert-butyl ether (MTBE). Calcium alginate, agar, polyacrylamide and polyvinvyl alcohol were screened as suitable immobilization matrices, with calcium alginate demonstrating the fastest MTBE-degradation rate. The rate was accelerated by 1.8-fold when the beads had been treated in physiological saline for 24h at 28 degrees C. MTBE degradation in mineral salts medium (MSM) was accompanied by the increase of biomass. The half-life of MTBE-degradation activity for the encapsulated cells stored at 28 degrees C was about 120 h, which was obviously longer than that of free cells (approximately 36 h). Efficient reusability of the beads up to 30 batches was achieved in poor nutrition solution as compared to only 6 batches in MSM. The immobilized cells could be operated in a packed-bed reactor for degradation of 10 mg L(-1) MTBE in groundwater with more than 99% removal efficiency at hydraulic retention time of 20 min. These results suggested that immobilized cells of PM1 in bioreactor might be applicable to a groundwater treatment system for the removal of MTBE.