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Sample records for styrene freshly added

  1. Study of the Influence of adding styrene-ethylene/butadiene-styrene in acrylonitrile-butadiene-styrene and polyethylene blends

    OpenAIRE

    M.A. Peydro; F. Parres; Navarro Vidal, Raúl; Sanchez-Caballero, Samuel

    2014-01-01

    This work studies the recovery of two grades of acrylonitrile butadiene styrene (ABS) contaminated with low-density polyethylene (LDPE), by adding styrene ethylene/butadiene styrene (SEBS). To simulate contaminated ABS, virgin ABS was mixed with 1, 2, 4, and 8% of LDPE and then extruded at 220°C. After this, the ABS with the highest percentage of LDPE (8%) was mixed with 1, 2, 4, and 8% of SEBS and then extruded. Different blends were mechanically, rheologically, optically, and dimensionally ...

  2. -Styrene)

    KAUST Repository

    Sutisna, Burhannudin

    2017-10-04

    Membranes are prepared by self-assembly and casting of 5 and 13 wt% poly(styrene-b-butadiene-b-styrene) (PS-b-PB-b-PS) copolymers solutions in different solvents, followed by immersion in water or ethanol. By controlling the solution-casting gap, porous films of 50 and 1 µm thickness are obtained. A gradient of increasing pore size is generated as the distance from the surface increased. An ordered porous surface layer with continuous nanochannels can be observed. Its formation is investigated, by using time-resolved grazing incident small angle X-ray scattering, electron microscopy, and rheology, suggesting a strong effect of the air-solution interface on the morphology formation. The thin PS-b-PB-b-PS ordered films are modified, by promoting the photolytic addition of thioglycolic acid to the polybutadiene groups, adding chemical functionality and specific transport characteristics on the preformed nanochannels, without sacrificing the membrane morphology. Photomodification increases fivefold the water permeance to around 2 L m(-2) h(-1) bar(-1) , compared to that of the unmodified one. A rejection of 74% is measured for methyl orange in water. The membranes fabrication with tailored nanochannels and chemical functionalities can be demonstrated using relatively lower cost block copolymers. Casting on porous polyacrylonitrile supports makes the membranes even more scalable and competitive in large scale.

  3. Experimental Investigations on Tribological Behaviour of Alumina Added Acrylonitrile Butadiene Styrene (ABS Composites

    Directory of Open Access Journals (Sweden)

    T. Panneerselvam

    2016-09-01

    Full Text Available Composite materials are multifunctional in nature, which can be custom-made based on the nature of the applications. The challenge of composite materials lie on complementing the properties of one another i.e. materials which go in the making of composites strengthen each other by inhibiting their weaknesses. Polymers are one of the widely used materials which serve a wide spectrum of engineering needs. In the present work, the tribological behaviour of a composite containing Acrylonitrile Butadiene Styrene (ABS and traces of Alumina is experimentally investigated. Alumina is added to ABS in various percentages such as 1%, and 3% by weight in order to improve the wear resistance of the polymer. Central Composite Design was used to design the experiments and a standard Pin-On-Disk apparatus was used to conduct the experiments. It is observed from the test results that the addition of alumina significantly enhances the wear behavior of the polymer. However, adding more percentage of alumina has led to adverse effect on wear resistance of polymer materials. Abrasive wear mechanism is found to be predominant in the case of alumina added composite materials. It is also found that 1% alumina added composite exhibits excellent wear properties compared to other materials.

  4. Effect of adding of the styrene-butadiene-styrene (SBS) copolymer in chemical and rheological properties of the brazilian asphalt; Efeito da adicao de SBS nas propriedades quimicas e reologicas de asfalto oriundo de petroleo brasileiro

    Energy Technology Data Exchange (ETDEWEB)

    Lucena, M.C.C.; Soares, S.A. [Ceara Univ., Fortaleza, CE (Brazil). Dept. de Quimica Organica e Inorganica]. E-mail: mccl@dqoi.ufc.br; sas@ufc.br; Soares, J.B. [Ceara Univ., Fortaleza, CE (Brazil). Dept. de Engenharia de Transportes]. E-mail: jsoares@det.ufc.br

    2003-07-01

    Chemical and rheological characterization of the asphalt cement (AC) from the Fazenda Alegre petroleum, and the effect of adding 4.5% of the styrene-butadiene-styrene (SBS) copolymer were investigated. Structural characteristics were analyzed by infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). A structure similar to the Arabian and Venezuelan petroleum was observed. The simulated aging led to structural modification noticed by the increment in the carbonyl and sulphoxide groups. Thermogravimetry (TGA) showed that SBS did not affect the AC thermal decomposition at both inert and oxidative atmosphere. However, the differential scanning calorimetry (DSC) showed a decrease in the glass transition temperature of the material when SBS was added. The effect of SBS on the absolute viscosity revealed that SBS is not an inert additive and causes an increase in viscosity, in a nonlinear fashion. The commonly found Newtonian behavior of asphalt binders under high temperatures was also found on the SBS modified binder. Dynamic mechanical tests have shown that SBS increases the binder performance grade. (author)

  5. THE VARIATION OF SOME BIOCHEMICAL PARAMETERS FROM FRESH COW CHEESE CREAM TYPE WITH ADDED AROMATIC PLANTS

    Directory of Open Access Journals (Sweden)

    CRISTIANA DIACONESCU

    2007-10-01

    Full Text Available Recent advanced studies in the field of cheese fabrication technology include, amongother, the usage of aromatic plants and spices as a mean of improving theorganoleptic properties and as a mean of decreasing the lipidic peroxidationphenomenon. For this purpose, three types of fresh cow cheese produced by S.C.Marion Invest Trade 94 SRL, experimentally added with dill, savory and rosemary,were comparatively studied from a chemical point of view (pH, acidity, humidity, ashand a biochemical point of view(raw fat, total proteins, total cholesterol, acidphosphatase’s enzymatic activity, superoxide dismutase’s enzymatic activity, calciumcontent.From a chemical point of view, no significant differences appeared between the creamcheese types analyzed, excepting the pH( lower in the cheeses with dill and rosemaryFrom a biochemical point of view, two phenomenon can be observed: a significantdecrease of the acidic phosphatase activity in the cheeses with added dill androsemary ( positively correlating with the pH value and decreased values of the SODactivity in all cheese types.

  6. The lycopene content in pulp ad peel of five fresh tomato varieties

    NARCIS (Netherlands)

    Markovic, K.; Panjkota-Krbavcic, I.; Krpan, M.; Bicanic, D.D.; Vahcic, N.

    2010-01-01

    The lycopene content in pulp and peel of five fresh tomato cultivars, most common on Croatian market, was determined by spectrophotometry and the high-performance liquid chromatography (HPLC). Peels from the raw tomatoes contained more lycopene (expressed on a fresh basis) than the pulps: the ratio

  7. Effect of adding unconventional raw materials on the technological properties of rice fresh pasta

    Directory of Open Access Journals (Sweden)

    Meg da Silva Fernandes

    2013-06-01

    Full Text Available The aim of this study was to develop fettuccini type rice fresh pasta by cold extrusion. To produce the pasta, a 2² Central Composite Rotational Design was used, in which the effects of the addition of pre-gelatinized rice flour - PGRF (0-60% and modified egg albumin - MEA (0-10% were studied. The dependent variables were the results of the cooking test and of the instrumental texture. The optimum cooking time for all of the formulations of rice fresh pasta was 3 minutes. MEA had a greater effect on increasing the weight of the pasta when compared to that of PGRF. It was found that with the addition of PGRF increase in loss of solids in cooking water, whereas MEA exerted the opposite effect on this parameter. Moreover, the maximum value of MEA (10% had an optimum effect on pasta firmness, while PGRF had a negative effect on this parameter. The maximum values of PGRF and MEA reduced the stickiness of the pasta. Based on these results and on the parameters considered as most important, the rice pasta with the best technological characteristics was that with the maximum levels of MEA (10% and no addition of PGRF (0%. This product was submitted to sensory and microbiological analyses, with good results.

  8. OXIDATIVE AND MICROBIOLOGICAL STABILITY OF FRESH PORK SAUSAGE WITH ADDED SUN MUSHROOM POWDER

    Directory of Open Access Journals (Sweden)

    Flávia Santi Stefanello

    2015-08-01

    Full Text Available Consumers are becoming more aware of the toxicological implications of artificial additives in foods. Natural antioxidants, in addition to reducing the deleterious effects of lipid oxidation, are currently extremely highly valued. This study aimed to invetigate the effect of addition of sun mushroom (Agaricus blazei Murrill powder on the oxidative and microbiological stability of pork sausage during the shelf life. This powder was used at concentrations of 0.0%, 1.0%, 2.0% and 4.0% in the sausages. Analyses of moisture, protein, ash, fat and microbiological analyses were performed on day 0. The sausages were analyzed on day 0 and every seven days in terms of pH, color, TBARS values ​​and microbiological analyses. The results of the proximal composition and microbiological analysis for coagulase positive Staphylococcus, coliforms at 35 ºC and 45 ºC, Salmonella sp and sulfite-reducing Clostridium were consistent with those required by Brazilian legislation. The color of the products was of a decreased redness At the end of the storage period, on the 35th day, the TBARS values for the sausage with 4.0% powder was 0.509±0.12 mg MDA/kg sample and for the control was 1.131±0.12 mg MDA/kg sample. The sun mushroom powder had no effect on microbiological stability. It is concluded that sun mushroom was effective in terms of the oxidative stability of pork sausage when added in powdered form at concentrations of 1.0%, 2.0% and 4.0%.

  9. Meat quality of rabbits reared with two different feeding strategies: with or without fresh alfalfa ad libitum

    Directory of Open Access Journals (Sweden)

    Gustavo Capra

    2013-03-01

    Full Text Available The aim of this study was to evaluate production performance, carcass characteristics and nutritive value of meat of rabbits reared under the 2 prevailing feeding strategies in Uruguay. One week after weaning, 96 purebred V line rabbits were randomly distributed between 2 treatments: (T1 commercial pelleted food ad libitum and (T2 commercial pelleted food ad libitum plus fresh alfalfa ad libitum. Each treatment included 12 cages containing 4 individuals each (2 males and 2 females. Growth performance characteristics (live weight evolution, commercial food consumption and food/gain ratio were evaluated. The consumption of alfalfa was not measured. Rabbits were slaughtered at a live weight of 2500 g and carcass characteristics were evaluated. Samples of meat and dissectible fat were analysed to determine intramuscular fat content at muscle L. dorsi, dissectible fat and intramuscular fat composition, minerals (Zn, Fe, Mg and Na, vitamin E and purines. Sensory evaluations were conducted to assess the effect of treatments on the consumer’s perception of differences and the existence of attributes determining preferences. Differences between treatments were significant for total commercial food intake (23 356 vs. 20 930 g/cage; P<0.001 and feed conversion ratio (3.82 vs. 3.41; P<0.01 for T1 and T2 respectively. No significant differences were found in average daily gain, age at slaughter and carcass characteristics. There were no significant differences in the intramuscular fat content. The fatty acid composition of dissectible and intramuscular fat was affected the inclusion of alfalfa in the diet increasing the linolenic acid content (1.82 vs. 3.28% and 2.29 vs. 5.15% for T1 and T2 at intramuscular and dissectible fat, respectively; P<0.001, and improving the n-6/n-3 relationship (8.60 vs. 5.82 and 11.58 vs. 5.64 for T1 and T2 at intramuscular and dissectible fat, respectively; P<0.001. There were no significant differences in vitamin E

  10. Magnolia bark extract increases oral bacterial cell surface hydrophobicity and improves self-perceived breath freshness when added to chewing gum

    NARCIS (Netherlands)

    Wessel, Stefan W.; van der Mei, Henny C.; Slomp, Anje M.; Belt-Gritter, van de Betsy; Maitra, Amarnath; Dodds, Michael W. J.; Busscher, Henk J.

    Magnolia bark extract (MBE) is a natural product used as an anti-inflammatory, anti platelet, and chemo-preventive agent. Here, we investigate the effects of MBE on the self perceived freshness of breath evaluated in ten human volunteers, who chewed gum with and without MBE added, as a functional

  11. Fresh fruit and vegetables and the added value of antioxidants: Attitudes of non-, light, and heavy organic food users

    NARCIS (Netherlands)

    Bartels, J.; Berg, van den I.

    2011-01-01

    Purpose – This study aims to focus on how to capitalise on the natural and logical alliance of nutrients in the marketing of fresh fruit and vegetables. Design/methodology/approach – A Dutch survey study was carried out among a representative sample of the Dutch population (n=492). Respondents

  12. Behavior of Staphylococcus aureus and autochthone microbiota in fresh sausages added of sodium nitrite and stored under refrigeration

    Directory of Open Access Journals (Sweden)

    Lucyanne Maria Moraes Correia

    2014-10-01

    Full Text Available Fresh sausages are cured meat products that may be contaminated with Staphylococcus aureus during the manufacturing procedure, which is frequently related with inadequate handling practices. The use of nitrite in meat products has proven efficacy against Clostridium botulinum, and studies indicate that bactericidal action against S. aureus depends on factors that are intrinsic and extrinsic to the product. The objective of the present study was to evaluate the effect of nitrite concentration, and pH on S. aureus and psychrotrophic autochthone microbiota in fresh sausages stored at different times and temperatures. Fresh sausage were produced at nitrite concentrations 50, 150 and 200ppm and contaminated with S. aureus. The sausages were storage at refrigeration (7 and 12°C and the quantification of S. aureus and psychrotrophic microorganisms was carried out on days 0, 2, 4, 7, and 10. Results showed that nitrite concentrations and the temperatures used had minimal effect on the multiplication of S. aureus and psychrotrophic autochthone microbiota. Final counts depended only on the length of storage: at the end of 10 days, counts were statistically similar in the different groups, showing that temperature and nitrite concentrations used did not control microbial growth effectively. It is suggested that the product should be stored below 7°C or at freezing temperatures for greater microbiological stability

  13. Morphology-properties relationship on nanocomposite films based on poly(styrene-block-diene-block-styrene copolymers and silver nanoparticles

    Directory of Open Access Journals (Sweden)

    2011-02-01

    Full Text Available A comparative study on the self-assembled nanostructured morphology and the rheological and mechanical properties of four different triblock copolymers, based on poly(styrene-block-diene-block-styrene and poly(styrene-block-diene-block-styrene matrices, and of their respective nanocomposites with 1 wt% silver nanoparticles, is reported in this work. In order to obtain well-dispersed nanoparticles in the block copolymer matrix, dodecanethiol was used as surfactant, showing good affinity with both nanoparticles and the polystyrene phase of the matrices as predicted by the solubility parameters calculated based on Hoftyzer and Van Krevelen theory. The block copolymer with the highest PS content shows the highest tensile modulus and tensile strength, but also the smallest elongation at break. When silver nanoparticles treated with surfactant were added to the block copolymer matrices, each system studied shows higher mechanical properties due to the good dispersion and the good interface of Ag nanoparticles in the matrices. Furthermore, it has been shown that semiempirical models such as Guth and Gold equation and Halpin-Tsai model can be used to predict the tensile modulus of the analyzed nanocomposites.

  14. Functionalized Nanochannels from Self-Assembled and Photomodified Poly(Styrene-b-Butadiene-b-Styrene).

    Science.gov (United States)

    Sutisna, Burhannudin; Polymeropoulos, George; Musteata, Valentina; Sougrat, Rachid; Smilgies, Detlef-M; Peinemann, Klaus-Viktor; Hadjichristidis, Nikolaos; Nunes, Suzana P

    2017-10-04

    Membranes are prepared by self-assembly and casting of 5 and 13 wt% poly(styrene-b-butadiene-b-styrene) (PS-b-PB-b-PS) copolymers solutions in different solvents, followed by immersion in water or ethanol. By controlling the solution-casting gap, porous films of 50 and 1 µm thickness are obtained. A gradient of increasing pore size is generated as the distance from the surface increased. An ordered porous surface layer with continuous nanochannels can be observed. Its formation is investigated, by using time-resolved grazing incident small angle X-ray scattering, electron microscopy, and rheology, suggesting a strong effect of the air-solution interface on the morphology formation. The thin PS-b-PB-b-PS ordered films are modified, by promoting the photolytic addition of thioglycolic acid to the polybutadiene groups, adding chemical functionality and specific transport characteristics on the preformed nanochannels, without sacrificing the membrane morphology. Photomodification increases fivefold the water permeance to around 2 L m(-2) h(-1) bar(-1) , compared to that of the unmodified one. A rejection of 74% is measured for methyl orange in water. The membranes fabrication with tailored nanochannels and chemical functionalities can be demonstrated using relatively lower cost block copolymers. Casting on porous polyacrylonitrile supports makes the membranes even more scalable and competitive in large scale. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Survey of volatile substances in kitchen utensils made from acrylonitrile–butadiene–styrene and acrylonitrile–styrene resin in Japan

    National Research Council Canada - National Science Library

    Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Kawamura, Yoko; Akiyama, Hiroshi

    2014-01-01

    Residual levels of 14 volatile substances, including 1,3‐butadiene, acrylonitrile, benzene, ethylbenzene, and styrene, in 30 kitchen utensils made from acrylonitrile–butadiene–styrene resin ( ABS ) and acrylonitrile–styrene resin...

  16. Binary and ternary LLE data of the system (ethylbenzene + styrene + 1-ethyl-3-methylimidazolium thiocyanate) and binary VLE data of the system (styrene + 1-ethyl-3-methylimidazolium thiocyanate)

    NARCIS (Netherlands)

    Jongmans, Mark; Schuur, Boelo; de Haan, A.B.

    2012-01-01

    The distillation of close boiling mixtures may be improved by adding a proper affinity solvent, and thereby creating an extractive distillation process. An example of a close boiling mixture that may be separated by extractive distillation is the mixture ethylbenzene/styrene. The ionic liquid

  17. Removal of styrene from waste gas stream using a biofilter

    Directory of Open Access Journals (Sweden)

    B Bina

    2004-12-01

    Full Text Available Background: Styrene is produced in large quantities in the chemical industries and it has been listed among the 189 hazardous and toxic atmospheric contaminants under Clean Air Act Amendments, 1990, due to its adverse effects on human health. The biofiltration has been widely and efficiently applied during recent decades for the treatment of air streams contaminated by volatile organic compounds at low concentrations. Also this technology has been applied widely and efficiently in the removal of styrene from waste gas streams. Methods: Biofiltration of waste gas stream polluted by styrene vapor was investigated in a three-stage bench scale reactor. Yard waste compost using shredded hard plastics as a bulking agent in a 75:25 v/v mix of plastics:compost was used to packing biofilter. The system inoculation was achieved by adding thickened activated sludge obtained from municipal wastewater treatment plant and the effects of loading rate, inlet concentration, and empty bed retention time variations on the performance and operation of biofilter were studied. Results: Microbial acclimation to styrene was achieved with inlet concentration of 65 ± 11 ppm and bed contact time of 360 s after 57 days of operation. Under steady state conditions experimental results showed equal average removal efficiency of about 84% at loading rates of 60 and 80 g m-3 h-1 with empty bed retention time of 60 s. Maximum elimination capacity was obtained up to 81 g m-3 h-1 with organic loading rate of about 120 g m-3 h-1. Reduction in performance was observed at inlet concentrations of upper than 650 ppm related to organic loading rates up to 160 g m-3 h-1 and then removal efficiency was decreased sharply. Evaluation of the concentration profile along the bed height of column indicated that the most value of elimination capacity occurred in the first section of biofilter. Elimination capacity also showed higher performance when empty bed retention time was reduced to 30 s

  18. Helbredsrisici ved eksponering for styren i glasfiberplastindustrien

    DEFF Research Database (Denmark)

    Kolstad, Henrik Albert; Ebbehøj, Nielse; Bonde, Jens Peter

    2012-01-01

    This is a summary of the health risks of occupational styrene exposure based on recent reviews. We conclude about the exposure levels that there is strong evidence that styrene causes acute irritation of eyes and respiratory tract above 25 ppm, genotoxic effects above 10 ppm, and persistent nervous...... or relevant exposure levels. We recommend reconsideration of the current Danish threshold limit value of 25 ppm, biological monitoring of styrene exposed workers, and epidemiological analyses of styrene exposure levels and long-term health effects among employees of the Danish reinforced plastics industry....... system effects with for instance reduced psychological performance, colour discrimination and hearing level following long-term styrene exposure above 10 ppm. There is moderate evidence of a causal association with cancer, but data are not sufficient to allow us to pinpoint specific cancers at risk...

  19. Acquired dyschromatopsia among styrene-exposed workers.

    Science.gov (United States)

    Gobba, F; Galassi, C; Imbriani, M; Ghittori, S; Candela, S; Cavalleri, A

    1991-07-01

    We investigated the occurrence of color vision loss in 75 styrene-exposed workers and in 60 referents. Color vision was evaluated by adopting the Lanthony D 15 desaturated panel, a test specifically suited to detect mild acquired dyschromatopsia. The results of the test were expressed as Color Confusion Index. Styrene exposure was evaluated with both environmental and biological monitoring. Airborne levels of the solvent were 3.2 to 549.5 mg/m3. In styrene-exposed workers color vision was significantly impaired when compared with referents matched for age. A significative correlation was found between environmental and urinary levels of styrene and Color Confusion Index excluding the influence of age in multiple regression analysis, indicating the possibility of a dose-effect relationship. The findings suggest that styrene can induce an early appearance of a dose-dependent color vision loss.

  20. Helbredsrisici ved eksponering for styren i glasfiberplastindustrien

    DEFF Research Database (Denmark)

    Kolstad, Henrik Albert; Ebbehøj, Nielse; Bonde, Jens Peter

    2012-01-01

    or relevant exposure levels. We recommend reconsideration of the current Danish threshold limit value of 25 ppm, biological monitoring of styrene exposed workers, and epidemiological analyses of styrene exposure levels and long-term health effects among employees of the Danish reinforced plastics industry.......This is a summary of the health risks of occupational styrene exposure based on recent reviews. We conclude about the exposure levels that there is strong evidence that styrene causes acute irritation of eyes and respiratory tract above 25 ppm, genotoxic effects above 10 ppm, and persistent nervous...... system effects with for instance reduced psychological performance, colour discrimination and hearing level following long-term styrene exposure above 10 ppm. There is moderate evidence of a causal association with cancer, but data are not sufficient to allow us to pinpoint specific cancers at risk...

  1. Influence of fresh date palm co-products on the ripening of a paprika added dry-cured sausage model system.

    Science.gov (United States)

    Martín-Sánchez, Ana María; Ciro-Gómez, Gelmy; Vilella-Esplá, José; Ben-Abda, Jamel; Pérez-Álvarez, José Ángel; Sayas-Barberá, Estrella

    2014-06-01

    Date palm co-products are a source of bioactive compounds that could be used as a new ingredient for the meat industry. An intermediate food product (IFP) from date palm co-products (5%) was incorporated into a paprika added dry-cured sausage (PADS) model system and was analysed for physicochemical parameters, lipid oxidation and sensory attributes during ripening. Addition of 5% IFP yielded a product with physicochemical properties similar to the traditional one. Instrumental colour differences were found, but were not detected visually by panellists, who also evaluated positively the sensory properties of the PADS with IFP. Therefore, the IFP from date palm co-products could be used as a natural ingredient in the formulation of PADS. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Study of the mechanical properties of Acrylonitrile Butadiene Styrene - High Impact Polystyrene blends with Styrene Ethylene Butylene Styrene

    OpenAIRE

    PEYDRO Miguel Angel; JUAREZ David; Sanchez-Caballero, Samuel; PARRES Francisco

    2013-01-01

    A binary blend Acrylonitrile Butadiene Styrene ¿ High Impact Polystyrene (ABS-HIPS 50% wt) was prepared on a twin-screw extruder at 190-210 oC. The different mechanical properties were then analyzed using tensile strength and impact tests. The analysis of mechanical properties showed a decrease in elongation at break and impact strength. On the other hand, we have prepared ternary blends of ABS-HIPS- Styrene Ethylene Butylene Styrene (SEBS), varying the percentage of SEBS from 10 to 30 %wt us...

  3. Microbial production of the aromatic building-blocks (S)-styrene oxide and (R)-1,2-phenylethanediol from renewable resources.

    Science.gov (United States)

    McKenna, Rebekah; Pugh, Shawn; Thompson, Brian; Nielsen, David R

    2013-12-01

    (S)-Styrene oxide and (R)-1,2-phenylethanediol are chiral aromatic molecular building blocks used commonly as precursors to pharmaceuticals and other specialty chemicals. Two pathways have been engineered in Escherichia coli for their individual biosynthesis directly from glucose. The novel pathways each constitute extensions of the previously engineered styrene pathway, developed by co-expressing either styrene monooxygenase (SMO) or styrene dioxygenase (SDO) to convert styrene to (S)-styrene oxide and (R)-1,2-phenylethanediol, respectively. StyAB from Pseudomonas putida S12 was determined to be the most effective SMO. SDO activity was achieved using NahAaAbAcAd of Pseudomonas sp. NCIB 9816-4, a naphthalene dioxygenase with known broad substrate specificity. Production of phenylalanine, the precursor to both pathways, was systematically enhanced through a number of mutations, most notably via deletion of tyrA and over-expression of tktA. As a result, (R)-1,2-phenylethanediol reached titers as high as 1.23 g/L, and at 1.32 g/L (S)-styrene oxide titers already approach their toxicity limit. As with other aromatics, product toxicity was strongly correlated with a model of membrane accumulation and disruption. This study additionally demonstrates that greater flux through the styrene pathway can be achieved if its toxicity is addressed, as achieved in this case by reacting styrene to less toxic products. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Grafting of styrene onto fluoropolymers films

    Energy Technology Data Exchange (ETDEWEB)

    Geraldes, Adriana N.; Zen, Heloisa A.; Parra, Duclerc F.; Lugao, Ademar B.; Linardi, Marcelo [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente], E-mail: angeral@ipen.br

    2007-07-01

    Grafting of styrene onto poly(vinylidenefluoride) (PVDF) and poly(tetrafluoroethylene) (PTFE) films was studied for the synthesis of ion exchange membranes. Radiation-induced grafting of styrene onto PVDF and PTFE films was investigated by simultaneous method using a Co{sup 60} source. The films of PVDF and PTFE were irradiated at total dose of 20 to 120 kGy and chemical changes were monitored after contact with styrene. Films of PTFE and PVDF were immersed in styrene/toluene 1:1 and were submitted to gamma radiation. After irradiation the samples were evaluated at periods of 0, 7, 14, 21 and 28 days, at room temperature in order to measure the grafting degree. Results of infrared spectroscopic analysis (FTIR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and the degree of grafting (DOG) were evaluated. The characterization techniques showed that irradiated PVDF and PTFE films exhibited a much higher grafting degree at 120 kGy. (author)

  5. Influence of the Nanoclay Cloisite 20A Incorporation on Properties of Acrylonitrile Butadiene Styrene (ABS)

    Science.gov (United States)

    Sales, Jorge N.; Silva, Andressa A.; Valenzuela-Diaz, Francisco R.; Moura, Esperidiana A. B.

    This work aims to study the influence of the nanoclay Cloisite 20A incorporation on mechanical properties of ABS (acrylonitrile butadiene styrene). The incorporation of Cloisite 20A was made in two steps; firstly, a masterbatch was preparated and then, it was incorporated in ABS. The Cloisite 20A masterbatch using 40 % of nanoclay and 60 % of SAN (Styrene Acrylonitrile) was prepared in an adiabatic mill. After that, Cloisite 20A masterbarch at 1 and 5 % (wt) was added in ABS. The resulting nanocomposites were characterized by tensile tests and the correlation between properties was discussed.

  6. Surfactant effects on morphology-properties relationships of silver-poly(styrene-b-isoprene-b-styrene) block copolymer nanocomposites.

    Science.gov (United States)

    Peponi, Laura; Tercjak, Agnieszka; Torre, Luigi; Kenny, Josè M; Mondragon, Iñaki

    2009-03-01

    Good dispersion of silver nanoparticles in poly(styrene-b-isoprene-b-styrene) block copolymer matrix has been achieved by adding dodecanethiol as surfactant to lower the high surface energy of metal nanoparticles. First, the influence of surfactant in the cylindrical nanostructure of neat block copolymer matrix has been analyzed. Taking into account the high solubility between dodecanethiol and the PS block of the SIS block copolymer, when silver nanoparticles and surfactant have been added to the block copolymer matrix its morphology changes from cylindrical to lamellar nanostructure. For the nanocomposite without surfactant, the block copolymer matrix loses its capability to self-assemble in lamellar nanostructure and in this case, agglomeration of silver nanoparticles occurs. Rheological, mechanical and morphological analysis were carried out in order to study the optimal content of surfactant necessary to obtain well-dispersed nanoparticles without worsen the final properties of the nanocomposite. The best silver/dodecanethiol w/w ratio appears to be 1, as confirmed by UV-Vis analysis. Moreover, semi-empirical models, such as Guth and Gold, and Halpin-Tsai, have been used in order to both predict and verify experimental tensile modulus of the obtained nanocomposites. The Guth and Gold equation, applicable to elastomers filled with spherical nanoparticles, provides a result closer to the experimental values than Halpin-Tsai model.

  7. Reactive processing of recycled polycarbonate/acrylonitrile butadiene styrene.

    Science.gov (United States)

    Jung, Woo-Hyuk; Choi, Yeon-Sil; Moon, Jung-Min; Tortorrela, Nathan; Beatty, Charles L; Lee, Jang-Oo

    2009-04-01

    Cellular phone housings were ground to make original particulates using a knife mill. Foams and adhesives with a lighter density than water were removed from ground mixtures using a sink-float process in water; ground metals, button rubbers, and wires were separated from desired materials by using a sink float process in salt All housing materials, consisting of seven thermoplastics included in cellular phone housings, showed better tensile properties than pure housing materials made of polycarbonate/acrylonitrile butadiene styrene, but they only had about half of the impact strength. In contrast, the low impact strength for all housing materials was improved by adding 25 wt % polyethylene elastomer and/or 2.4 wt % ground epoxy circuit boards for batch mixing. Impact strengths, tensile strengths, and the energy absorption ability of all housing materials were improved by adding 5.4wt% glycidyl methacrylate for twin screw extrusion.

  8. 78 FR 6213 - Styrene-2-Ethylhexyl Acrylate Copolymer; Tolerance Exemption

    Science.gov (United States)

    2013-01-30

    ... AGENCY 40 CFR Part 180 Styrene-2-Ethylhexyl Acrylate Copolymer; Tolerance Exemption AGENCY: Environmental...; also known as styrene-2-ethylhexyl acrylate copolymer when used as an inert ingredient in a pesticide...-risk polymers are described in 40 CFR 723.250(d). Styrene-2-ethylhexyl acrylate copolymer conforms to...

  9. 21 CFR 177.1810 - Styrene block polymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Styrene block polymers. 177.1810 Section 177.1810... FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1810 Styrene block polymers. The styrene...

  10. Hemocompatibility of styrenic block copolymers for use in prosthetic heart valves.

    Science.gov (United States)

    Brubert, Jacob; Krajewski, Stefanie; Wendel, Hans Peter; Nair, Sukumaran; Stasiak, Joanna; Moggridge, Geoff D

    2016-02-01

    Certain styrenic thermoplastic block copolymer elastomers can be processed to exhibit anisotropic mechanical properties which may be desirable for imitating biological tissues. The ex-vivo hemocompatibility of four triblock (hard-soft-hard) copolymers with polystyrene hard blocks and polyethylene, polypropylene, polyisoprene, polybutadiene or polyisobutylene soft blocks are tested using the modified Chandler loop method using fresh human blood and direct contact cell proliferation of fibroblasts upon the materials. The hemocompatibility and durability performance of a heparin coating is also evaluated. Measures of platelet and coagulation cascade activation indicate that the test materials are superior to polyester but inferior to expanded polytetrafluoroethylene and bovine pericardium reference materials. Against inflammatory measures the test materials are superior to polyester and bovine pericardium. The addition of a heparin coating results in reduced protein adsorption and ex-vivo hemocompatibility performance superior to all reference materials, in all measures. The tested styrenic thermoplastic block copolymers demonstrate adequate performance for blood contacting applications.

  11. Survey of volatile substances in kitchen utensils made from acrylonitrile–butadiene–styrene and acrylonitrile–styrene resin in Japan

    OpenAIRE

    Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Kawamura, Yoko; Akiyama, Hiroshi

    2014-01-01

    Residual levels of 14 volatile substances, including 1,3-butadiene, acrylonitrile, benzene, ethylbenzene, and styrene, in 30 kitchen utensils made from acrylonitrile–butadiene–styrene resin (ABS) and acrylonitrile–styrene resin (AS) such as slicers, picks, cups, and lunch boxes in Japan were simultaneously determined using headspace gas chromatography/mass spectroscopy (HS-GC/MS). The maximum residual levels in the ABS and AS samples were found to be 2000 and 2800 μg/g of styrene, respectivel...

  12. Polystyrene cups and containers: styrene migration.

    Science.gov (United States)

    Tawfik, M S; Huyghebaert, A

    1998-07-01

    The level of styrene migration from polystyrene cups was monitored in different food systems including: water, milk (0.5, 1.55 and 3.6% fat), cold beverages (apple juice, orange juice, carbonated water, cola, beer and chocolate drink), hot beverages (tea, coffee, chocolate and soup (0.0, 0.5, 1, 2, and 3.6% fat), take away foods (yogurt, jelly, pudding and ice-cream), as well as aqueous food simulants (3% acetic acid, 15, 50, and 100% ethanol) and olive oil. Styrene migration was found to be strongly dependent upon the fat content and storage temperature. Drinking water gave migration values considerably lower than all of the fatty foods. Ethanol at 15% showed a migration level equivalent to milk or soup containing 3.6% fat. Maximum observed migration for cold or hot beverages and take-away foods was 0.025% of the total styrene in the cup. Food simulants were responsible for higher migration (0.37% in 100% ethanol). A total of 60 food samples (yogurt, rice with milk, fromage, biogardes, and cheese) packed in polystyrene containers were collected from retail markets in Belgium, Germany, and the Netherlands. The level of styrene detected in the foods was always fat dependent.

  13. Catalytic dehydrogenations of ethylbenzene to styrene

    NARCIS (Netherlands)

    Kapteijn, F.; Makkee, M.; Nederlof, C.

    This research work on the catalytic dehydrogenation of ethylbenzene (EB) to styrene (ST) had a primary goal of developing improved catalysts for dehydrogenation processes both in CO2 as well as with O2 that can compete with the conventional dehydrogenation process in steam. In order to achieve this

  14. Graft Copolymerization and Characterization of Styrene with ...

    African Journals Online (AJOL)

    MBI

    2017-05-24

    May 24, 2017 ... 1Department of Chemistry, Faculty of Science, Northwest University, P.M.B 3220, Kano, Nigeria. 2Department of Pure and ... In this study, styrene was successfully grafted onto chitosan by conventional free radical polymerization technique, using ..... radical species is very high, chain transfer and reaction ...

  15. Study of the thermal properties of Acrylonitrile Butadiene Styrene - High Impact Polystyrene blends with Styrene Ethylene Butylene Styrene

    OpenAIRE

    PEYDRO Miguel Angel; JUAREZ David; Sanchez-Caballero, Samuel; PARRES Francisco

    2013-01-01

    A binary blend Acrylonitrile Butadiene Styrene ¿ High Impact Polystyrene (ABS-HIPS 50% wt) was prepared on a twin-screw extruder at 190-210 oC. The different properties were then analyzed using melt flow index (MFI), thermogravimetric analysis (TGA), and Fourier Transform Infrared spectroscopy (FTIR). FTIR analysis indicated heterogeneous distribution of the blend in injected pieces and SEM micrographs show heterogeneous distribution of both phase (ABS and HIPS). On the other hand, we have pr...

  16. Styrene polymerization in three-component cationic microemulsions

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Luna, V.H.; Puig, J.E. (Universidad de Guadalajara (Mexico)); Castano, V.M. (Instituto de Fisica (Mexico)); Rodriguez, B.E.; Murthy, A.K.; Kaler, E.W. (Univ. of Delaware, Newark (USA))

    1990-06-01

    The polymerization of styrene in three-component dodecyltrimethylammonium bromide (DTAB) microemulsions is reported. The structure of the unpolymerized microemulsions, determined by conductimetry and quasielastic light scattering (QLS), is consistent with styrene-swollen micelles in equilibrium with regular micelles, both dispersed in an aqueous phase. Polymerization of these transparent microemulsions, monitored by QLS an dilatometry, produced stable, bluish monodisperse microlatices with particle radii ranging from 20 to 30 nm, depending on styrene content. Polymerization initiation appears to occur in the styrene-swollen micelles, and the polymer particles grow by recruiting monomer and surfactant from uninitiated droplets and small micelles.

  17. Hydrothermal Synthesis of Fe3O4 Nanoparticles and Flame Resistance Magnetic Poly styrene Nanocomposite

    Directory of Open Access Journals (Sweden)

    Kambiz Hedayati

    2017-01-01

    Full Text Available Fe3O4 nanostructures were synthesized via a facile hydrothermal reaction. The effect of various surfactants such as cationic and anionic on the morphology of the product was investigated. Magnetic nanoparticles were added to poly styrene for preparation of magnetic nanocomposite. Nanostructures were then characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The magnetic properties of the samples were also investigated using vibrating sample magnetometer. The magnesium ferrite nanoparticles exhibit super paramagnetic behaviour at room temperature, with a saturation magnetization of 66 emu/g and a coercivity less than 5 Oe. Distribution of the magnetic nanoparticles into poly styrene matrix increases the coercivity. Nanoparticles appropriately enhanced flame retardant property of the PS matrix. Nanoparticles act as barriers which decrease thermal transport and volatilization during decomposition of the polymer.

  18. Morphology and Phase Transitions in Styrene-Butadiene-Styrene Triblock Copolymer Grafted with Isobutyl Substituted Polyhedral Oligomeric Silsesquioxanes (Postprint)

    National Research Council Canada - National Science Library

    Drazowski, Daniel B; Lee, Andre; Haddad, Timothy S

    2007-01-01

    Two symmetric triblock polystyrene-butadiene-polystyrene (SBS) copolymers with different styrene content were grafted with varying amounts of isobutyl-substituted polyhedral oligomeric silsesquioxane (POSS) molecules...

  19. Styrene exposure during the manufacturing of reinforced fiberglass pipe

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, K.E.

    1986-01-01

    Considering the large number of employees exposed to airborne styrene during the manufacturing of reinforced fiberglass pipe and the absence of appropriate information to define airborne styrene exposure and the resulting levels of urinary mandelic acid, it was necessary that these parameters be evaluated in an actual industrial setting in order to appropriately monitor and control health hazards in the work place. Styrene measurements were collected at eight work stations over a 5-year period at the world's largest manufacturer of styrenated reinforced fiberglass pipe. Pre- and post-shift urinary mandelic acid was measured for 16 employees for 3-consecutive days. The data obtained were statistically analyzed to determine the mean styrene exposure at each work station and the relationship between airborne styrene and pre-and post-shift urinary mandelic acid. The results of this study indicated that both the pre- and post-shift urinary mandelic acid measurements can be utilized to confirm human exposure to styrene. Post-shift measurements are more reflective of daily variations in styrene exposure, whereas pre-shift urinary mandelic acid was found to correlate best to the long-term airborne styrene concentrations (r = 0.787). The prediction equations of NIOSH and ACGIH for the arithmetic mean airborne styrene concentration from post-shift mandelic acid were not valid for the low levels of styrene exposure and urinary mandelic acid concentrations found in this study. Significant changes in the post-shift to pre-shift urinary mandelic acid concentrations were observed.

  20. Lipid-induced degradation in biocompatible poly(Styrene-Isobutylene-Styrene) (SIBS) thermoplastic elastomer.

    Science.gov (United States)

    Fittipaldi, Mauro; Grace, Landon R

    2017-04-01

    The thermoplastic elastomer Poly(Styrene-block-Isobutylene-block-Styrene) (SIBS) is highly biocompatible, which has led to its use in several commercially-available implants. However, lipid-induced degradation has been previously identified as a primary cause of failure in long-term SIBS implants subject to mechanical loading. Thus, understanding the mechanisms and extent of lipid-induced damage and the role of styrene-isobutylene ratio and molecular weight is critical to improving longevity of SIBS-based implants in order to fully exploit the biocompatibility advantages. Samples of four different SIBS formulations were fabricated via compression molding, immersed to lipid saturation contents from 5 to 80% by weight, and tested in uniaxial tension, stress relaxation, and dynamic creep modes. Degradation mechanisms were investigated via infrared spectroscopy, chromatography, and microscopy. No evidence of lipid-induced chemical interactions or chain scissoring was observed. However, a decrease in tensile strength, loss of dynamic creep performance and faster relaxation with increasing lipid content is attributed to strong internal straining. The magnitude of these losses is inversely proportional to both molecular weight and styrene content, suggesting that selection of these variables during the design phase should be based not only on the mechanical requirements of the application, but the expected degree of lipid exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. 40 CFR 721.10151 - Modified styrene, divinylbenzene polymer (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified styrene, divinylbenzene polymer (generic). 721.10151 Section 721.10151 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10151 Modified styrene, divinylbenzene polymer (generic). (a) Chemical...

  2. Otoacoustic emission sensitivity to exposure to styrene and noise.

    Science.gov (United States)

    Sisto, R; Cerini, L; Gatto, M P; Gherardi, M; Gordiani, A; Sanjust, F; Paci, E; Tranfo, G; Moleti, A

    2013-11-01

    The ototoxic effect of the exposure to styrene is evaluated, also in the presence of simultaneous exposure to noise, using otoacoustic emissions as biomarkers of mild cochlear damage. Transient-evoked and distortion product otoacoustic emissions were recorded and analyzed in a sample of workers (15 subjects) exposed to styrene and noise in a fiberglass manufacturing facility and in a control group of 13 non-exposed subjects. Individual exposure monitoring of the airborne styrene concentrations was performed, as well as biological monitoring, based on the urinary concentration of two styrene metabolites, the Mandelic and Phenylglyoxylic acids. Noise exposure was evaluated using wearable phonometers, and hearing loss with pure tone audiometry. Due to their different job tasks, one group of workers was exposed to high noise and low styrene levels, another group to higher styrene levels, close to the limit of 20 ppm, and to low noise levels. A significant negative correlation was found between the otoacoustic emission levels and the concentration of the styrene urinary metabolites. Otoacoustic emissions, and particularly distortion products, were able to discriminate the exposed workers from the controls, providing also a rough estimate of the slope of the dose-response relation between otoacoustic levels and styrene exposure.

  3. Synthesis and antibacterial activities of cyclodimers of styrene oxides

    African Journals Online (AJOL)

    A simple synthetic procedure for preparation of 1,4-dioxanes or 1,3-dioxolanes from styrene oxides is described. Electron-donating groups on the aromatic ring of the styrene oxides were found to favour formation of 1,4-dioxanes while electron-withdrawing groups favoured formation of 1,3-dioxolanes. Antibacterial activities ...

  4. Grafting of styrene onto polypropylene membranes

    Energy Technology Data Exchange (ETDEWEB)

    Zen, Heloisa A.; Geraldes, Adriana N.; Parra, Duclerc F.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], E-mail: helozen@ipen.br

    2007-07-01

    The grafting of styrene onto polypropylene (PP) by simultaneous radiation was carried out. The effects of absorbed dose and the pos radiation period on the grafting yield were investigated. The experiment comprised PP films with 40{mu}m thickness exposed to gamma ionizing radiation at room temperature and nitrogen atmosphere. The films were immersed in styrene/toluene and then irradiated at total dose of 40, 80 and 100 kGy. After irradiation the samples were evaluated at periods of 0, 7, 14, 21 and 28 days at room temperature in order to observe the behavior of grafting degree. Structural, chemical changes and surface morphologies of the modified PP films were characterized by infrared spectroscopic analysis (FTIR), differential scanning calorimetry analysis (DSC), thermogravimetric analysis (TGA) and the degree of grafting (DOG) was gravimetrically determined. The simultaneous radiation indicated the dependency of the percent graft on the absorbed dose. The DOG values are higher when the film was submitted at 100 kGy dose. The thermal stability shows a decrease in the degradation temperature of the modified samples in comparison with the pure polymer. (author)

  5. 75 FR 9438 - Americas Styrenics, LLC-Marietta Plant a Subsidiary of Americas Styrenics, LLLC Formerly Known as...

    Science.gov (United States)

    2010-03-02

    ... Americas Styrenics LLC, including on- site leased workers from Pioneer Pipe Co., Marietta, Ohio. The notice... Employment and Training Administration Americas Styrenics, LLC-Marietta Plant a Subsidiary of Americas... Pioneer Pipe Co.: Marietta, OH; Amended Certification Regarding Eligibility To Apply for Worker Adjustment...

  6. Biocompatibility and characterization of polylactic acid/styrene-ethylene-butylene-styrene composites.

    Science.gov (United States)

    Tsou, Chi-Hui; Kao, Bo-Jyue; Yang, Ming-Chien; Suen, Maw-Cherng; Lee, Yi-Hsuan; Chen, Jui-Chin; Yao, Wei-Hua; Lin, Shang-Ming; Tsou, Chih-Yuan; Huang, Shu-Hsien; De Guzman, Manuel; Hung, Wei-Song

    2015-01-01

    Polylactic acid (PLA)/styrene-ethylene-butylene-styrene (SEBS) composites were prepared by melt blending. Differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WXRD) were used to characterize PLA and PLA/SEBS composites in terms of their melting behavior and crystallization. Curves from thermal gravimetric analysis (TGA) illustrated that thermostability increased with SEBS content. Further morphological analysis of PLA/SEBS composites revealed that SEBS molecules were not miscible with PLA molecules in PLA/SEBS composites. The tensile testing for PLA and PLA/SEBS composites showed that the elongation at the break was enhanced, but tensile strength decreased with increasing SEBS content. L929 fibroblast cells were chosen to assess the cytocompatibility; the cell growth of PLA was found to decrease with increasing SEBS content. This study proposes possible reasons for these properties of PLA/SEBS composites.

  7. Neurobehavioral effects of acute styrene exposure in fiberglass boatbuilders

    Energy Technology Data Exchange (ETDEWEB)

    Letz, R.; Mahoney, F.C.; Hershman, D.L.; Woskie, S.; Smith, T.J. (Mount Sinai School of Medicine, New York, NY (USA))

    1990-11-01

    A field investigation of the effects of acute exposure to styrene among fiberglass boatbuilders was performed. Personal samples of styrene in breathing zone air and postshift urinary mandelic acid were collected for 105 workers exposed and not exposed to styrene in 6 fiberglass boatbuilding companies in New England. Three tests from the computerized Neurobehavioral Evaluation System (NES) were performed by the subjects in the morning before exposure to styrene, near midday, and at the end of the work day. Duration of exposure averaged 2.9 years (SD = 4.6), 8-hour TWA styrene exposure averaged 29.9 ppm (SD = 36.2), and urinary mandelic acid averaged 347 mg/g creatinine (SD = 465). Regression analyses indicated a statistically significant relationship between postshift performance on the Symbol-Digit test and both acute styrene exposure and mandelic acid. Other analyses comparing workers exposed to less than 50 ppm and greater than 50 ppm styrene also showed a significant effect on Symbol-Digit performance. All three NES tests showed test-retest correlation coefficients above .80, and ease of use for collection of neurobehavioral data under field conditions was demonstrated.

  8. Preliminary study of styrene grafting on polyethylene films

    Energy Technology Data Exchange (ETDEWEB)

    Moraes, Gilberto de O.; Geraldes, Adriana N.; Zen, Heloisa A.; Parra, Duclerc F.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], E-mail: gibamaclarenn@hotmail.com

    2007-07-01

    Grafting of styrene on polyethylene was carried out as a preliminary study. The experiments covered a range from 5 to 20 kGy and intended to evaluate the absorbed dose that led to the best degree of grafting (DOG) under industrial dose rate. PE films 0,065 mm thick were exposed several times to radiation at room temperature and nitrogen atmosphere. The films were immersed in the solution content styrene/solvent then irradiated (5 to 20 kGy) dose. As an exploratory experiment, styrene grafting was gravimetrically evaluated and characterized by infrared spectroscopy (FTIR).The degree of grafting (DOG) was calculated. Concentrations of methanol/ Styrene at the rate of 80:20 were favorable at low dose of 10 kGy. In presence of acid, best result was achieved at 15 kGy in the range of 5 to 20 kGy. (author)

  9. Relation between colour vision loss and occupational styrene exposure level

    OpenAIRE

    Gong, Y; Kishi, R.; Katakura, Y; Tsukishima, E; Fujiwara, K.; Kasai, S; Satoh, T.; Sata, F; Kawai, T.

    2002-01-01

    Aims: To investigate the relation between colour vision loss and the exposure level of styrene. Exposure level included the current exposure concentration, past cumulative exposure, and the maximum exposure level in the past.

  10. Dynamic response of acrylonitrile butadiene styrene under impact loading

    National Research Council Canada - National Science Library

    Owolabi, Gbadebo; Peterson, Alex; Habtour, Ed; Riddick, Jaret; Coatney, Michael; Olasumboye, Adewale; Bolling, Denzell

    2016-01-01

    ... rateloading.Tensile tests were conducted on 3-D printed acrylonitrile butadiene styrene (ABS) at differentstrain rates, according to the ASTM D638 standard, to assess its strain rate sensitivity under quasi-staticloads...

  11. Styrene-Associated Health Outcomes at a Windblade Manufacturing Plant

    Science.gov (United States)

    McCague, Anna-Binney; Cox-Ganser, Jean M.; Harney, Joshua M.; Alwis, K. Udeni; Blount, Benjamin C.; Cummings, Kristin J.; Edwards, Nicole; Kreiss, Kathleen

    2015-01-01

    Background Health risks of using styrene to manufacture windblades for the green energy sector are unknown. Methods Using data collected from 355 (73%) current windblade workers and regression analysis, we investigated associations between health outcomes and styrene exposure estimates derived from urinary styrene metabolites. Results The median current styrene exposure was 53.6 mg/g creatinine (interquartile range: 19.5–94.4). Color blindness in men and women (standardized morbidity ratios 2.3 and 16.6, respectively) was not associated with exposure estimates, but was the type previously reported with styrene. Visual contrast sensitivity decreased and chest tightness increased (odds ratio 2.9) with increasing current exposure. Decreases in spirometric parameters and FeNO, and increases in the odds of wheeze and asthma-like symptoms (odds ratios 1.3 and 1.2, respectively) occurred with increasing cumulative exposure. Conclusions Despite styrene exposures below the recommended 400 mg/g creatinine, visual and respiratory effects indicate the need for additional preventative measures in this industry. PMID:26305283

  12. Toxicity of the components of styrene polymers: polystyrene, acrylonitrile-butadiene-styrene (ABS) and styrene-butadiene-rubber (SBR). Reactants and additives.

    Science.gov (United States)

    Fishbein, L

    1984-01-01

    The toxicity of the components of styrene polymers, e.g., polystyrene, ABS and SBR, were reviewed with primary focus on the reactive monomers (except styrene) (e.g., acrylonitrile, butadiene) as well as on impurities and solvents such as benzene, hexane and methylethyl ketone, and additives such as phenyl-2-naphthylamine, di-n-butyl phthalate, and a number of peroxide initiators and flame retardants (e.g., 2,3-dibromopropanol, decadibromodiphenyl oxide and antimony trioxide). It is stressed that toxicity data are generally lacking for the majority of additives employed in the production of styrene polymers. Information is also lacking as to the numbers of individuals at potential risk and the extent of their exposure to the large number of additives employed.

  13. MODELING STYRENE HYDROGENATION KINETICS USING PALLADIUM CATALYSTS

    Directory of Open Access Journals (Sweden)

    G. T. Justino

    Full Text Available Abstract The high octane number of pyrolysis gasoline (PYGAS explains its insertion in the gasoline pool. However, its use is troublesome due to the presence of gum-forming chemicals which, in turn, can be removed via hydrogenation. The use of Langmuir-Hinshelwood kinetic models was evaluated for hydrogenation of styrene, a typical gum monomer, using Pd/9%Nb2O5-Al2O3 as catalyst. Kinetic models accounting for hydrogen dissociative and non-dissociative adsorption were considered. The availability of one or two kinds of catalytic sites was analyzed. Experiments were carried out in a semi-batch reactor at constant temperature and pressure in the absence of transport limitations. The conditions used in each experiment varied between 16 - 56 bar and 60 - 100 ºC for pressure and temperature, respectively. The kinetic models were evaluated using MATLAB and EMSO software. Models using adsorption of hydrogen and organic molecules on the same type of site fitted the data best.

  14. Hairy AdS solitons

    Energy Technology Data Exchange (ETDEWEB)

    Anabalón, Andrés, E-mail: andres.anabalon@uai.cl [Departamento de Ciencias, Facultad de Artes Liberales and Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Av. Padre Hurtado 750, Viña del Mar (Chile); Astefanesei, Dumitru, E-mail: dumitru.astefanesei@pucv.cl [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile); Choque, David, E-mail: brst1010123@gmail.com [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile); Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile)

    2016-11-10

    We construct exact hairy AdS soliton solutions in Einstein-dilaton gravity theory. We examine their thermodynamic properties and discuss the role of these solutions for the existence of first order phase transitions for hairy black holes. The negative energy density associated to hairy AdS solitons can be interpreted as the Casimir energy that is generated in the dual filed theory when the fermions are antiperiodic on the compact coordinate.

  15. [Styrene migration into wine contained in polyester resin tanks].

    Science.gov (United States)

    Giffone, M; Brun, S

    1978-01-01

    The use of polyester resins in wine tanks manufacture or coating has widely spread during the past five years; this type of material has been and is still the source of organoleptic damage due to non polymerized sytrene migration into urine. Sytrene is a solvant often used in resin polymerization: it act as a reticulation agent of insaturated linear polyester. Polymerization at room temperature is allowed gy additives but has to be completed in warm air or in steam. An excess of styrene is often used for a polymerisation as complete as possible and remains on a free form. Then it migrates from the tank walls into the wine. For a better understanding of the styrene migration mechanism studies were performed on two levels: from small containers (4 l) kept in the laboratory and from tanks (30 hl) set up in an I.N.R.A. wine estate in all conditions usually realized in practice. Influence of time, temperature and alcohol content were studied. Styrene migration was interpreted as a diffusion phenomenom and styrene diffusion coefficients were calculated for several temperatures. Knowledge of these coefficients and of styrene content of the tank walls allow the prediction of a tank behaviour in time. Other substances that styrene were detected in wine and in tank walls, they are impurities either from resins like ethylbenzene, or from the catalyst like mesityl oxide. The lattest has never been mentioned in the litterature. From the results obtained it is possible to give some advices to manufacturers and users of polyester resin tanks, about the quality of raw materials, resins and additives along with the conditions carried and for their use and about the control of monomer styrene content in the walls of just manufactured tank.

  16. Spectrophotometric study of the interaction of methylene blue with poly(styrene-co-sodium styrene sulfonate

    Directory of Open Access Journals (Sweden)

    Souha Ben Mahmoud

    2016-05-01

    Full Text Available The interaction of the cationic phenothiazine dye, the Methylene Blue (MB with poly-(sodium styrene sulfonatef–co-(styrene1-f, (PSSNa f, has been investigated by spectrophotometric method. The polyelectrolyte induced metachromasy resulting in a blue shift of the absorption maxima of the dye, in agreement with the formation of dye H-aggregates. The stability of the PSSNa-MB complexes was studied as a function of polyelectrolyte chain length, polyelectrolyte electrostatic charge density f, polyelectrolyte concentration, NaCl salt addition, tetrahydrofurane (THF addition and THF treatment. The stoichiometry of PSSNa-MB complex evaluated by the molar ratio method was found 4:1 for the fully charged PSSNa f = 1. Reversal of metachromasy was observed upon salt and THF addition, while THF treatment does not affect the complex and allows recovering the initial complex. Finally, thermodynamic parameters of the interaction between the polyelectrolyte and the dye at different temperatures, namely free energy DG, the enthalpy DH and the entropy DS have been evaluated to determine the binding constant and as a consequence the stability of the complex. The metachromasy effect was found to be more high as the chemical charge f increases and reaches its maximum value f = 1, when operating at optimal conditions. So, the PSSNa f = 1-MB complex is the most stable in comparison to the others based on lower charge density PSSNa f.

  17. New styrene-b-isobutylene-b-styrene (SIBS) glaucoma drainage implant

    Science.gov (United States)

    Orozco, Marcia A.; Acosta, Ana C.; Espana, Edgar M.; Pinchuk, Leonard; Weber, Bruce; Davis, Stewart; Arrieta, Esdras; Dubovy, Sander; Fantes, Francisco; Aly, Mohamed; Zhou, Yonghua; Parel, Jean-Marie

    2006-02-01

    Purpose: To design and test the Miami-InnFocus Drainage Implant (MiDi) as a glaucoma shunt that is biocompatible, flexible, and significantly smaller than existing commercial implants in order to prevent postoperative hypotony, inflammation, scarring, erosion, and extrusion. Methods: A new biomaterial composed of styrene-b-isobutylene-b-styrene (SIBS) was used in a novel design for a glaucoma drainage implant. The implant consists of a tube 11mm long with an inner diameter of 70, 100, and 150 μm and outer diameter of 250 μm with a 1mm2 tab located 4.5mm from the proximal tip to prevent migration. The device was implanted in 15 New Zealand White rabbits for biocompatibility and efficacy testing. A similarly designed implant made of polydimethylsiloxane was implanted in 6 other animals as a pseudo-control. Typical GDI implantation technique was modified for this device. The proximal end of the new SIBS implant was inserted 2mm into the anterior chamber and the distal end placed in a subconjunctival space created by the surgeon. Biocompatibility of the device was studied by slit-lamp follow-up and intraocular pressure (IOP) measurements recorded periodically. Results: Biocompatibility of the MiDi was excellent. A low and diffuse bleb was observed with these devices. All SIBS tubes were patent 9 months after insertion. Immunostaining demonstrated non-continuous deposition of collagen with virtually no encapsulation. No macrophages or myofibroblast were visible around the SIBS polymer which was found more bioinert than the control PDMS. Conclusion: This newly designed glaucoma implant is clinically biocompatible in the rabbit model and maintained 100% patency at 9 months.

  18. Conceptual process design of extractive distillation processes for ethylbenzene/styrene separation

    NARCIS (Netherlands)

    Jongmans, Mark; Hermens, E.; Raijmakers, M.; Maassen, J.I.W.; Schuur, Boelo; de Haan, A.B.

    2012-01-01

    In the current styrene production process the distillation of the close-boiling ethylbenzene/styrene mixture to obtain an ethylbenzene impurity level of 100 ppm in styrene accounts for 75–80% of the energy requirements. The future target is to reach a level of 1–10 ppm, which will increase the

  19. 78 FR 20032 - Styrene-Ethylene-Propylene Block Copolymer; Tolerance Exemption

    Science.gov (United States)

    2013-04-03

    ... AGENCY 40 CFR Part 180 Styrene-Ethylene-Propylene Block Copolymer; Tolerance Exemption AGENCY... from the requirement of a tolerance for residues of styrene-ethylene-propylene block copolymer (CAS Reg... permissible level for residues of styrene-ethylene-propylene block copolymer on food or feed commodities...

  20. Controlled Functionalization of Olefin/styrene Copolymers through Free Radical Processes

    NARCIS (Netherlands)

    Passaglia, Elisa; Aglietto, Mauro; Ciardelli, Francesco; Picchioni, Francesco

    2000-01-01

    The functionalization of styrene-b-(ethylene-co-1-butene)-b-styrene triblock copolymer (SEBS) and styrene-co-butadiene (SBR) random copolymer by free radical processes is presented. SEBS was functionalized in the melt with diethyl maleate (DEM) and dicumyl peroxide (DCP) as initiator. The

  1. Side chain alkylation of toluene with methanol over basic zeolites - novel production route towards styrene?

    NARCIS (Netherlands)

    Rep, M.; Rep, M.

    2002-01-01

    Styrene is an important monomer for the production of different types of (co-) polymers that are used in, e.g., toys, medical devices, food packaging, paper coatings etc. Styrene is produced with several different industrial processes. In 1998, the production of styrene monomer was approximately 21

  2. 40 CFR 721.9492 - Polymers of styrene, cyclohexyl methacrylate and substituted methacrylate.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of styrene, cyclohexyl... Significant New Uses for Specific Chemical Substances § 721.9492 Polymers of styrene, cyclohexyl methacrylate...) The chemical substances identified generically as polymers of styrene, cyclohexyl methacrylate and...

  3. 21 CFR 177.1040 - Acrylonitrile/styrene copoly-mer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylonitrile/styrene copoly-mer. 177.1040 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1040 Acrylonitrile/styrene copoly-mer. Acrylonitrile/styrene copolymers identified in this section may be safely used as a component...

  4. In vitro evolution of styrene monooxygenase from Pseudomonas putida CA-3 for improved epoxide synthesis

    NARCIS (Netherlands)

    Gursky, Lucas J.; Nikodinovic-Runic, Jasmina; Feenstra, K Anton; O'Connor, Kevin E.

    2010-01-01

    The styAB genes from Pseudomonas putida CA-3, which encode styrene monooxygenase, were subjected to three rounds of in vitro evolution using error-prone polymerase chain reaction with a view to improving the rate of styrene oxide and indene oxide formation. Improvements in styrene monooxygenase

  5. 77 FR 13015 - Fresh Fruit and Vegetable Program

    Science.gov (United States)

    2012-03-05

    ... and Program Development Branch, Child Nutrition Division, Food and Nutrition Service, USDA, 3101 Park...; ] DEPARTMENT OF AGRICULTURE Food and Nutrition Service 7 CFR Parts 211 and 235 RIN 0584-AD96 Fresh Fruit and...

  6. Simultaneous production of biobased styrene and acrylates using ethenolysis

    NARCIS (Netherlands)

    Spekreijse, J.; Notre, le J.E.L.; Haveren, van J.; Scott, E.L.; Sanders, J.P.M.

    2012-01-01

    Phenylalanine (1), which could be potentially obtained from biofuel waste streams, is a precursor of cinnamic acid (2) that can be converted into two bulk chemicals, styrene (3) and acrylic acid (4), via an atom efficient pathway. With 5 mol% of Hoveyda–Grubbs 2nd generation catalyst, 1 bar of

  7. Graft copolymerization and characterization of styrene with chitosan ...

    African Journals Online (AJOL)

    In this study, styrene was successfully grafted onto chitosan by conventional free radical polymerization technique, using potassium persulphate (KPS) as the initiator. The effect of various reaction conditions including chitosan:monomer weight ratio, polymerization temperature, reaction time and concentration of initiator ...

  8. Terpolymerization of 2-ethoxy ethylmethacrylate, styrene and maleic ...

    Indian Academy of Sciences (India)

    Terpolymerization of 2-ethoxyethyl methacrylate (2-EOEMA), styrene (St) and maleic anhydride (Ma) initiated by benzoyl peroxide was carried out in acetone as common solvent for three monomers. The structure and composition of terpolymer were determined by FTIR spectroscopy by recording analytical absorption bands ...

  9. Adding Ajax

    CERN Document Server

    Powers, Shelley

    2007-01-01

    Ajax can bring many advantages to an existing web application without forcing you to redo the whole thing. This book explains how you can add Ajax to enhance, rather than replace, the way your application works. For instance, if you have a traditional web application based on submitting a form to update a table, you can enhance it by adding the capability to update the table with changes to the form fields, without actually having to submit the form. That's just one example.Adding Ajax is for those of you more interested in extending existing applications than in creating Rich Internet Applica

  10. Occupational Styrene Exposure on Auditory Function Among Adults: A Systematic Review of Selected Workers

    Directory of Open Access Journals (Sweden)

    Francis T. Pleban

    2017-12-01

    Full Text Available A review study was conducted to examine the adverse effects of styrene, styrene mixtures, or styrene and/or styrene mixtures and noise on the auditory system in humans employed in occupational settings. The search included peer-reviewed articles published in English language involving human volunteers spanning a 25-year period (1990–2015. Studies included peer review journals, case–control studies, and case reports. Animal studies were excluded. An initial search identified 40 studies. After screening for inclusion, 13 studies were retrieved for full journal detail examination and review. As a whole, the results range from no to mild associations between styrene exposure and auditory dysfunction, noting relatively small sample sizes. However, four studies investigating styrene with other organic solvent mixtures and noise suggested combined exposures to both styrene organic solvent mixtures may be more ototoxic than exposure to noise alone. There is little literature examining the effect of styrene on auditory functioning in humans. Nonetheless, findings suggest public health professionals and policy makers should be made aware of the future research needs pertaining to hearing impairment and ototoxicity from styrene. It is recommended that chronic styrene-exposed individuals be routinely evaluated with a comprehensive audiological test battery to detect early signs of auditory dysfunction. Keywords: auditory system, human exposure, ototoxicity, styrene

  11. Survey of volatile substances in kitchen utensils made from acrylonitrile-butadiene-styrene and acrylonitrile-styrene resin in Japan.

    Science.gov (United States)

    Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Kawamura, Yoko; Akiyama, Hiroshi

    2014-05-01

    Residual levels of 14 volatile substances, including 1,3-butadiene, acrylonitrile, benzene, ethylbenzene, and styrene, in 30 kitchen utensils made from acrylonitrile-butadiene-styrene resin (ABS) and acrylonitrile-styrene resin (AS) such as slicers, picks, cups, and lunch boxes in Japan were simultaneously determined using headspace gas chromatography/mass spectroscopy (HS-GC/MS). The maximum residual levels in the ABS and AS samples were found to be 2000 and 2800 μg/g of styrene, respectively. The residual levels of 1,3-butadiene ranged from 0.06 to 1.7 μg/g in ABS, and three of 15 ABS samples exceeded the regulatory limit for this compound as established by the European Union (EU). The residual levels of acrylonitrile ranged from 0.15 to 20 μg/g in ABS and from 19 to 180 μg/g in AS. The levels of this substance in seven ABS and six AS samples exceeded the limit set by the U.S. Food and Drug Administration (FDA). Furthermore, the levels of acrylonitrile in three AS samples exceeded the voluntary standard established by Japanese industries. These results clearly indicate that the residual levels of some volatile compounds are still high in ABS and AS kitchen utensils and further observations are needed.

  12. Survey of volatile substances in kitchen utensils made from acrylonitrile–butadiene–styrene and acrylonitrile–styrene resin in Japan

    Science.gov (United States)

    Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Kawamura, Yoko; Akiyama, Hiroshi

    2014-01-01

    Residual levels of 14 volatile substances, including 1,3-butadiene, acrylonitrile, benzene, ethylbenzene, and styrene, in 30 kitchen utensils made from acrylonitrile–butadiene–styrene resin (ABS) and acrylonitrile–styrene resin (AS) such as slicers, picks, cups, and lunch boxes in Japan were simultaneously determined using headspace gas chromatography/mass spectroscopy (HS-GC/MS). The maximum residual levels in the ABS and AS samples were found to be 2000 and 2800 μg/g of styrene, respectively. The residual levels of 1,3-butadiene ranged from 0.06 to 1.7 μg/g in ABS, and three of 15 ABS samples exceeded the regulatory limit for this compound as established by the European Union (EU). The residual levels of acrylonitrile ranged from 0.15 to 20 μg/g in ABS and from 19 to 180 μg/g in AS. The levels of this substance in seven ABS and six AS samples exceeded the limit set by the U.S. Food and Drug Administration (FDA). Furthermore, the levels of acrylonitrile in three AS samples exceeded the voluntary standard established by Japanese industries. These results clearly indicate that the residual levels of some volatile compounds are still high in ABS and AS kitchen utensils and further observations are needed. PMID:24936293

  13. Crystallization analysis fractionation of poly(ethylene-co-styrene) produced by metallocene catalysts

    KAUST Repository

    Kamal, Muhammad Shahzad

    2013-06-06

    Ethylene homo polymer and ethylene-styrene copolymers were synthesized using Cp2ZrCl2 (1)/methyl aluminoxane (MAO) and rac-silylene-bis (indenyl) zirconium dichloride (2)/MAO catalyst systems by varying styrene concentration and reaction conditions. Crystallization analysis fractionation (CRYSTAF), DSC, FTIR and 1H NMR spectroscopy were used for characterizing the synthesized polymers. Interestingly, styrene was able to increase the activity of 1/MAO and 2/MAO catalyst systems at low concentrations, but at higher concentrations the activity decreases. The 1/MAO system at low and high pressure was unable to incorporate styrene, and the final product was pure polyethylene. On the other hand, with 2/MAO polymerization of ethylene and styrene yielded copolymer containing both styrene and ethylene. Results obtained from CRYSTAF and DSC reveal that on using 1/MAO system at high pressure, the resulting polymer in the presence of styrene has similar crystallinity as the polymer produced without styrene. Using both 1/MAO at low pressure and 2/MAO leads to decrease in crystallinity with increase in styrene concentration, even though the former does not incorporate styrene. © 2013 Springer-Verlag Berlin Heidelberg.

  14. Styren a styren-7,8-oxid:metabolismus a analytické metody stanovení aduktů s proteiny

    Czech Academy of Sciences Publication Activity Database

    Jágr, Michal; Pacáková, V.; Petříček, Miroslav

    2009-01-01

    Roč. 103, č. 11 (2009), s. 902-910 ISSN 0009-2770 Institutional research plan: CEZ:AV0Z50200510 Keywords : styren * adducts * styren-7,8-oxid Subject RIV: EE - Microbiology, Virology Impact factor: 0.717, year: 2009

  15. Intelligent Fish Freshness Assessment

    Directory of Open Access Journals (Sweden)

    Hamid Gholam Hosseini

    2008-01-01

    Full Text Available Fish species identification and automated fish freshness assessment play important roles in fishery industry applications. This paper describes a method based on support vector machines (SVMs to improve the performance of fish identification systems. The result is used for the assessment of fish freshness using artificial neural network (ANN. Identification of the fish species involves processing of the images of fish. The most efficient features were extracted and combined with the down-sampled version of the images to create a 1D input vector. Max-Win algorithm applied to the SVM-based classifiers has enhanced the reliability of sorting to 96.46%. The realisation of Cyranose 320 Electronic nose (E-nose, in order to evaluate the fish freshness in real-time, is experimented. Intelligent processing of the sensor patterns involves the use of a dedicated ANN for each species under study. The best estimation of freshness was provided by the most sensitive sensors. Data was collected from four selected species of fishes over a period of ten days. It was concluded that the performance can be increased using individual trained ANN for each specie. The proposed system has been successful in identifying the number of days after catching the fish with an accuracy of up to 91%.

  16. Styrene-based shape memory foam: fabrication and mathematical modeling

    Science.gov (United States)

    Yao, Yongtao; Zhou, Tianyang; Qin, Chao; Liu, Yanju; Leng, Jinsong

    2016-10-01

    Shape memory polymer foam is a promising kind of structure in the biomedical and aerospace field. Shape memory styrene foam with uniform and controlled open-cell structure was successfully fabricated using a salt particulate leaching method. Shape recovery capability exists for foam programming in both high-temperature compression and low-temperature compression (Shape recovery properties such as shape fixing property and shape recovery ratio were also characterized. In order to provide guidance for the future fabrication of shape memory foam, the theories of Gibson and Ashby as well as differential micromechanics theory were applied to predict Young’s modulus and the mechanical behavior of SMP styrene foams during the compression process.

  17. Effect of ultrasonic pretreatment on emulsion polymerization of styrene.

    Science.gov (United States)

    Nagatomo, Daichi; Horie, Takafumi; Hongo, Chizuru; Ohmura, Naoto

    2016-07-01

    This study investigated the effect of pretreatment of ultrasonic irradiation on emulsion polymerization of styrene to propose a process intensification method which gives high conversion, high reaction rate, and high energy efficiency. The solution containing styrene monomer was irradiated by a horn mounted on the ultrasonic transducer with the diameter of 5mm diameter and the frequency of 28 kHz before starting polymerization. The pretreatment of ultrasound irradiation as short as 1 min drastically improved monomer dispersion and increased reaction rate even under the agitation condition with low rotational speed of impeller. Furthermore, the ultrasonic pretreatment resulted in higher monomer concentration in polymer particles and produced larger polymer particles than conventional polymerization without ultrasonic pretreatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Fall From High and Acute Styrene Exposure : A Case Report

    Directory of Open Access Journals (Sweden)

    Ferhat Ižcme

    2016-01-01

    Full Text Available Styrene is a benzene derivative of the aromatic hydrocarbon which is widely used in the manufacture of plastics industry, synthetic rubber and insulating materials. Its toxic effects occur by inhalation of its vapor or by direct contact. In acute intoxication irritation in the eye and skin may occur and chemical pneumonitis may develop in the lungs due to inhalation. It dissolves in ethanol, benzene, acetone and ether. Water solubility is low. In this paper we present the management of a patient who after falling down from the scaffold which is approximately 5 meters of height, a tin of styrene on the same scaffold spilled on him and we would like to draw attention to the need for decontamination chamber which is not available in the most of the emergency departments in our country.

  19. Acute behavioral effects of styrene exposure: a further analysis

    Energy Technology Data Exchange (ETDEWEB)

    Cherry, N.; Rodgers, B.; Venables, H.; Waldron, H.A.; Wells, G.G.

    1981-11-01

    Studies were carried out on two groups to styrene-based resin. Early morning urinary mandelic acid concentrations after two days without exposure correlated with reaction time measured on arrival at work. Men were found to differ considerably in their rate of clearance of mandelic acid-those with slow reaction times. After some months at reduced exposure, a small group of men with previously high mandelic acid concentrations has speeded up on the reaction time task.

  20. Confined space hazards: combined exposure to styrene, fiberglass, and silica.

    Science.gov (United States)

    Shields, P G; McCunney, R J; Chase, K H

    1995-02-01

    Work in confined spaces continues to present hazards to workers. The magnitude of this problem was recently addressed by the Occupational Safety and Health Administration in its Final Rule for "Permit-Required Control Spaces for General Industry" (29 CFR Parts 1910). Although illness and injury are typically due to asphyxiation, explosion, and drowning, toxic exposures also are an important risk. We describe herein four workers engaged in erosion-proofing enclosed chemical tanks with minimal ventilation and no respiratory protection. They were exposed to styrene-based solvents, styrene-based resins, silica, and fiberglass dust. Each experienced acute neurological effects and bronchitis. One worker developed a life-threatening pneumonia that resulted in numerous complications. The severity of the illness, which would likely not have otherwise occurred, resulted from impaired lung defense mechanisms due to the combined exposures. Several studies support the association of styrene exposure and respiratory illness that may be compounded by co-exposure to fiberglass in unique circumstances. To prevent the hazards of confined space, recommended procedures should be followed, including those established by the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration.

  1. Styrene biofiltration in a trickle-bed reactor

    Directory of Open Access Journals (Sweden)

    V. Novak

    2008-04-01

    Full Text Available The biological treatment of styrene waste gas in a trickle-bed filter (TBF was investigated. The bioreactor consisted of a two-part glass cylinder (ID 150 mm filled with 25 mm polypropylene Pall rings serving as packing material. The bed height was 1m. Although the laboratory temperature was maintained at 22 ºC, the water temperature in the trickle-bed filter was slightly lower (about 18 ºC.The main aim of our study was to observe the effect of empty-bed residence time (EBRT on bioreactor performance at a constant pollutant concentration over an extended time period. The bioreactor was inoculated with a mixed microbial consortium isolated from a styrene-degrading biofilter that had been running for the previous two years. After three weeks of acclimation period, the bioreactor was loaded with styrene (100 mg.m-3. EBRT was in the range of 53 s to 13 s. A maximum elimination capacity (EC of 11.3 gC.m-3.h-1 was reached at an organic loading (OL rate of 18.6 gC.m-3.h-1.

  2. Recycling cycle of materials applied to acrylonitrile-butadiene-styrene/policarbonate blends with styrene-butadiene-styrene copolymer addition

    Science.gov (United States)

    Cândido, L. H. A.; Ferreira, D. B.; Júnior, W. Kindlein; Demori, R.; Mauler, R. S.

    2014-05-01

    The scope of this research is the recycling of polymers from mobile phones hulls discarded and the performance evaluation when they are submitted to the Recycling Cycle of Materials (RCM). The studied material was the ABS/PC blend in a 70/30 proportion. Different compositions were evaluated adding virgin material, recycled material and using the copolymer SBS as impact modifier. In order to evaluate the properties of material's composition, the samples were characterized by TGA, FTIR, SEM, IZOD impact strength and tensile strength tests. At the first stage, the presented results suggest the composition containing 25% of recycled material and 5% of SBS combines good mechanical performance to the higher content of recycled material and lower content of impact modifier providing major benefits to recycling plans. Five cycles (RCM) were applied in the second stage; they evidenced a decrease trend considering the impact strength. At first and second cycle the impact strength was higher than reference material (ABS/PC blend) and from the fourth cycle it was lower. The superiority impact strength in the first and second cycles can be attributed to impact modifier effect. The thermal tests and the spectrometry didn't show the presence of degradation process in the material and the TGA curves demonstrated the process stability. The impact surface of each sample was observed at SEM. The microstructures are not homogeneous presenting voids and lamellar appearance, although the outer surface presents no defects, demonstrating good moldability. The present work aims to assess the life cycle of the material from the successive recycling processes.

  3. Chromosomal aberrations in lymphocytes of workers exposed to low levels of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Nordenson, I.; Beckman, L.

    1984-01-01

    Chromosomal aberrations were studied in lymphocytes of 15 workers exposed to styrene and 13 controls. The average styrene concentration in the work room air was 24 ppm, and the levels of urinary mandelic acid were below 2 mmol/l. No significant increase in the rates of gaps and breaks was found. However, the rate of micronuclei was significantly increased, which indicates that the mitotic spindle mechanism may be more sensitive to styrene and its metabolites than DNA.

  4. Thermal Stability and Flammability of Styrene-Butadiene Rubber-Based (SBR) Ceramifiable Composites

    National Research Council Canada - National Science Library

    Anyszka, Rafał; Bieliński, Dariusz; Pędzich, Zbigniew; Rybiński, Przemysław; Imiela, Mateusz; Siciński, Mariusz; Zarzecka-Napierała, Magdalena; Gozdek, Tomasz; Rutkowski, Paweł

    2016-01-01

    Ceramifiable styrene-butadiene (SBR)-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers...

  5. Estudo de custo-rendimento do precessamento de queijos tipo minas frescal com derivado de soja e diferentes agentes coagulantes Study of cost and yield of minas like fresh cheese produced with added fat freee soybean hydro-soluble extract powder with curd formed by different coagulants agents

    Directory of Open Access Journals (Sweden)

    R. D. Neves-Souza

    2005-03-01

    Full Text Available O desenvolvimento de alimentos é uma constante nas indústrias, nas universidades e nos institutos de pesquisa visando otimizar processamentos, agregar diferentes ingredientes em produtos já existentes, entre outros fatores. Após o desenvolvimento de um produto, informações adicionais podem ser obtidas pela determinação do rendimento e do custo do produto final. O objetivo deste trabalho foi estimar o rendimento e o custo de queijos Minas frescal tradicionais e adicionados de extrato hidrossolúvel de soja desengordurado (EHS processados com coalho bovino e com coagulante microbiano (Aspergillus niger var. awamori. A introdução de 8% do EHS (em relação ao teor de sólidos totais do leite no queijo Minas frescal processado com coalho bovino proporcionou rendimento em gramas de sólidos totais por litro de leite (g ST/L superior de 16,67% em relação ao queijo Minas frescal tradicional processado com o mesmo coalho. O queijo tipo Minas frescal processado com coagulante microbiano e com 8% de EHS apresentou rendimento (g ST/L superior de 16,54%, quando comparado ao seu tradicional. O custo das formulações-base (kg de queijo/100L de leite processadas com coalho bovino e com coagulante microbiano foi US$ 36,75 e US$ 37,50, respectivamente, ao passo que os queijos tradicionais processados com os mesmos agentes coagulantes apresentaram custo equivalente a US$ 35,12 e US$ 35,36.Food products development occur in industries, universities and research centers with the aim of optimizing processes, to include different ingredients to existing products or for other reasons. After developing a product, additional information may be obtained by determining yield and cost of the final product. The objective of this research was to estimate yield and cost of traditional Minas fresh cheese and those produced with added fat free soybean hydro-soluble extract powder (SEP, with curd formed by rennet or microbial coagulant (Aspergillus niger var

  6. Styrene exposure and biologic monitoring in FRP boat production plants

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, M.; Koizumi, A.; Miyasaka, M.; Watanabe, T.

    1982-02-01

    A survey on styrene exposure was conducted in five small to medium-sized fiber-reinforced plastic (FRP) boat plants utilizing carbon felt dosimeters as personal and stationary samplers to measure 4h (TWA) exposure during workday afternoons. The heaviest exposure, up to 256 ppm by personal sampling and 174 ppm by stationary sampling, took place during the lamination on a mold to produce a boat shell, and the work inside narrow holds also resulted in exposures of a comparable degree. Styrene levels were much lower in other auxiliary works. The TWA of exposure in an entire boat production was estimated to be 40-50 ppm. Installation of several flexible hoses as an exhaust system was proved to be effective in decreasing the vapor concentration. Gas masks were also useful in reducing the exposure. Urine samples were collected from 96 male workers at the end of 8h work (4h in the morning and 4h in the afternoon) and also from 22 nonexposed male subjects, and analyzed for mandelic acid (MA), phenylglyoxylic acid (PhGA), and hippuric acid (HA). When the results of urinalyses were compared with 4-h styrene TWA as monitored by personal sampling, the best correlation was obtained with MA + PhGA/creatinine (the correlation coefficient, 0.88), followed by MA (0.84). For these two cases, regression lines and 95% confidence limits for the group means and for the individual values were calculated. The urinary level of MA, PhGA, and HA in the 22 nonexposed male subjects were also tabulated.

  7. Devulcanization of styrene butadiene (SBR) waste tire by controlled oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Rios, Rachel R.V.A.; Gontijo, Manuela; Ferraz, Vany P.; Lago, Rochel M.; Araujo, Maria Helena [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica]. E-mail: mharaujo@ufmg.br

    2006-05-15

    This work describes the devulcanization of vulcanized SBR (Styrene Butadiene Rubber) based on controlled oxidation with nitric acid. IR, {sup 1}H and {sup 13}C-NMR, CHN elemental analyses, TG, GPC and TPD-MS (Temperature Programmed Decomposition-Mass Spectrometry) experiments suggest that nitric acid promotes two processes: devulcanization by oxidation of the sulfide crosslinks and oxidation of the carbon framework leading to the formation of -COOH and -NO{sub 2} groups. Under aggressive conditions (HNO{sub 3}, reflux) the polymer chain is strongly oxidized and fragmented to a highly oxygenated low molecular weight fraction, which is soluble in water. (author)

  8. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Butyl acrylate, polymer with... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane...

  9. 76 FR 77709 - Butyl acrylate-methacrylic acid-styrene polymer; Tolerance Exemption

    Science.gov (United States)

    2011-12-14

    ... AGENCY 40 CFR Part 180 Butyl acrylate-methacrylic acid-styrene polymer; Tolerance Exemption AGENCY...-propenoate and ethenylbenzene (CAS Reg. No. 25036-16-2); also known as butyl acrylate-methacrylic acid...-risk polymers are described in 40 CFR 723.250(d). Butyl acrylate-methacrylic acid-styrene polymer...

  10. EVALUATION OF STYRENE EMISSIONS FROM A SHOWER STALL/BATHTUB MANUFACTURING FACILITY

    Science.gov (United States)

    The report gives results of emissions measurements carried out at a representative facility (Eljer Plumbingware in Wilson, NC) that manufactures polyester-resin-reinforced shower stalls and bathtubs by spraying styrene-based resins onto molds in vented, open, spray booths. Styren...

  11. ADDENDUM TO ASSESSMENT OF STYRENE EMISSION CONTROLS FOR FRP/C AND BOAT BUILDING INDUSTRIES

    Science.gov (United States)

    This report is an addendum to a 1996 report, Assessment of Styrene Emission Controls for FRP/C and Boat Building Industries. It presents additional evaluation of the biological treatment of styrene emissions, Dow Chemical Company's Sorbathene solvent vapor recovery system, Occupa...

  12. 21 CFR 177.2710 - Styrene-divinylbenzene resins, cross-linked.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Styrene-divinylbenzene resins, cross-linked. 177.2710 Section 177.2710 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... resins, cross-linked. Styrene-divinylbenzene cross-linked copolymer resins may be safely used as articles...

  13. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, condensated... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

  14. 21 CFR 173.70 - Chloromethylated aminated styrene-divinylbenzene resin.

    Science.gov (United States)

    2010-04-01

    ... resin. 173.70 Section 173.70 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Chloromethylated aminated styrene-divinylbenzene resin. Chloromethylated aminated styrene-divinylbenzene copolymer... resin dispersion. (c) The additive is used as a decolorizing and clarification agent for treatment of...

  15. Utilizing the phenol byproducts of coke production: 3. Phenols as coinhibitors of thermopolymerization during styrene production

    Energy Technology Data Exchange (ETDEWEB)

    I.I. Batura; A.F. Gogotov; V.I. Cherepanov; O.I. Baranov; A.A. Levchuk; M.V. Parilova [Irkutsk State Technical University, Irkutsk (Russian Federation)

    2009-01-15

    A new oligomerization procedure for phenol byproducts from coke production is experimentally studied. This method, oxidative combination, is intended to produce an effective coinhibitor of styrene thermopolymerization. When combined with a Mannich base, the new oligomer exhibits excellent inhibiting properties in the heat treatment of styrene and matches the effectiveness of imported inhibitors based on nitroxyl radicals. 15 refs., 1 tab.

  16. Exploiting Framework Flexibility of a Metal-Organic Framework for Selective Adsorption of Styrene over Ethylbenzene

    NARCIS (Netherlands)

    Mukherjee, S.; Joarder, B.; Desai, A.V.; Manna, B.; Krishna, R.; Ghosh, S.K.

    2015-01-01

    The separation of styrene and ethylbenzene mixtures is industrially important and is currently performed in highly energy-intensive vacuum distillation columns. The primary objective of our investigation is to offer an energy-efficient alternative for selective adsorption of styrene by a flexible

  17. Addition of whey protein to fresh cheese.

    Directory of Open Access Journals (Sweden)

    José Rafael Arce-Méndez

    2015-12-01

    Full Text Available This work has been conducted in order to assess the effect of adding whey protein (WP to fresh cheese. The yield, proximal chemical composition, tryptophan content,and texture and consumer sensorial acceptance were obtained. The study was conducted at a cheese factory located in San Carlos, Costa Rica, in 2011. The protein obtained from whey was added during the cheese manufacturing process, before adding the microbial rennet; and four enrichment levels were evaluated, including one control. The supplemented cheese showed an acceptance rating between 6.8 and 7.1. Products with 75 and 120 g of added whey protein per kilogram of milk showed no significant differences versus non-supplemented cheese, while the preference towards the cheese with 150 g WP/kg was less than that of the control (p<0.05. A cluster analysis revealed the existence of two consumer groups: one, accounting for 65% of the members of the panel, whose preference was unaffected by the protein supplemented; and, the other group where the added protein affected their liking negatively. Adding whey protein to the cheese resulted in a significant increase in yield and in the protein-to-water ratio, as well as a reduction in fat content (p<0.05. Nevertheless, there were structural changes in the cheese that caused the reduction of certain texture properties, generating changes in their sensory properties that reduced the preference of a representative group of consumers towards the product.

  18. Organocatalytic chemo- and regioselective oxyarylation of styrenes via a cascade reaction: remote activation of hydroxyl groups.

    Science.gov (United States)

    Zhang, Yu-Chen; Jiang, Fei; Wang, Shu-Liang; Shi, Feng; Tu, Shu-Jiang

    2014-07-03

    The first organocatalytic oxyarylation of styrenes has been established through a cascade of vinylogous Michael addition/alkoxyl transfer reactions of o- or p-hydroxylstyrenes with quinone imine ketals. The process leads to a highly chemo- and regioselective oxyarylation of styrenes and provides access to m-alkylated anilines in generally high yields and excellent diastereoselectivity (up to 99% yield, >95:5 dr). An investigation of the reaction pathway revealed that the existence and position of the hydroxyl group of styrene played crucial roles in the cascade reaction, suggesting that the two reactants were simultaneously activated by binaphthyl-derived phosphoric acid via hydrogen bonding interactions and long-distance conjugative effects. In addition, the activating group of the hydroxyl functionality in the products can be easily removed or transformed, demonstrating the applicability and utility of this strategy in styrene oxyarylation and in the synthesis of styrene-based compounds.

  19. Human exposure to styrene. IV. Industrial hygiene investigations and biological monitoring in the polyester industry

    Energy Technology Data Exchange (ETDEWEB)

    Guillemin, M.P.; Bauer, D.; Martin, B.; Marazzi, A.

    1982-01-01

    An industrial hygiene study of 10 glassfiber reinforced polyester plants (including 90 workers) was undertaken to investigate the styrene exposure in this industry and to estimate biological limit values (BLV's) for the urinary metabolites of styrene: mandelic (MA) and phenylglyoxylic acids (PGA). Time weighted average (TWA) styrene exposures were found ranging from 2 to 200 ppm. The urinary elimination of metabolites correlated well with exposure and the BLV's corresponding to an 8-h exposure at 100 ppm were consistent with earlier laboratory findings (end-of-shift sample: MA 1640, PGA 510, MA + PGA 2150; next-morning sample: MA 330, PGA 330, MA + PGA 660 mg/g creat.). Total metabolites (MA + PGA) in the next-morning sample or mandelic acid in the end-of-shift sample are recommended for routine monitoring of exposure to styrene. The study revealed the need for further research on how to reduce styrene exposure in this industry.

  20. No acute behavioral effects of exposure to styrene: a safe level of exposure

    Energy Technology Data Exchange (ETDEWEB)

    Edling, C.; Ekberg, K.

    1985-05-01

    To determine whether exposure to low levels of styrene (below 110 mg/m3) causes acute behavioral effects and symptoms that may be related to concentrations of styrene in air or urinary mandelic acid or both, 12 men occupationally exposed to styrene were studied and compared with a reference group of 10 unexposed men. Simple reaction time was measured before and after work and information about symptoms was obtained by questionnaire. Active and passive sampling of airborne styrene was carried out and urinary mandelic acid concentrations were measured. Although the size of the study groups is small, the results indicate that exposure to styrene below 110 mg/m3 does not cause any acute adverse effects on the central nervous system.

  1. 40 CFR 63.500 - Back-end process provisions-carbon disulfide limitations for styrene butadiene rubber by emulsion...

    Science.gov (United States)

    2010-07-01

    ... disulfide limitations for styrene butadiene rubber by emulsion processes. 63.500 Section 63.500 Protection... limitations for styrene butadiene rubber by emulsion processes. (a) Owners or operators of sources subject to this subpart producing styrene butadiene rubber using an emulsion process shall operate the process...

  2. 40 CFR 721.7020 - Distillates (petroleum), C(3-6), polymers with styrene and mixed terpenes (generic name).

    Science.gov (United States)

    2010-07-01

    ...), polymers with styrene and mixed terpenes (generic name). 721.7020 Section 721.7020 Protection of...), C(3-6), polymers with styrene and mixed terpenes (generic name). (a) Chemical substance and...), polymers with styrene and mixed terpenes (PMN P-89-676) is subject to reporting under this section for the...

  3. Computational Modeling of Polystyrene-b-(ethylene-co-butylene)-b-styrene and Mineral Oil Gels and Nanocomposites

    Science.gov (United States)

    Chantawansri, T. L.; Berg, M.; Mrozek, R.; Stokes, K.; Henz, B.; Chung, P.; Beyer, F.; Lenhart, J.; Andzelm, J. W.

    2010-03-01

    There has been substantial interest in thermoplastic elastomer (TPE) gels composed of poly(styrene-b-(ethylene-co-butylene)-b-styrene)(SEBS) and hydrocarbon oils. Although the effects of adding nanoparticles on TPE gels is relatively unexplored, research in polymer nanocomposites have shown that the addition of nanoparticles enhanced physical properties. The microstructure of such a system is dependent on a variety of parameters such as block copolymer and nanoparticle concentrations, temperature, nanoparticle size, and nanoparticle interaction; thus to perform an extensive study of phase space, mesoscale modeling should be used in conjunction with the experimentation. To complement our experimental system, mesoscale modeling of this TPE gel and the corresponding nanocomposite are preformed using dynamic density functional theory and self consistent field theory through Materials Studio, where morphology of the system is studied as a function of various parameters and conditions. The validity of the computational methods has been confirmed for a number of experimental results, and subsequently has been used to explore a larger design space than is accessible solely through experimental methods.

  4. Vegetable-Oil-Based Hyperbranched Polyester-Styrene Copolymer Containing Silver Nanoparticle as Antimicrobial and Corrosion-Resistant Coating Materials

    Directory of Open Access Journals (Sweden)

    Manawwer Alam

    2013-01-01

    Full Text Available Pongamia oil (PO was converted to Pongamia oil hydroxyl (POH via epoxidation process. The esterification of POH with linolenic acid was carried out to form hyperbranched polyester (HBPE, and further styrenation was performed at the conjugated double bond in the chain of linolenic acid. After styrenation, silver nanoparticle was added in different weight percentages (0.1–0.4 wt%. The structural elucidation of POH, HBPE, and HBPE-St was carried out by FT-IR, 1H-NMR, and 13C-NMR spectroscopic techniques. Physicochemical and physicomechanical analyses were performed by standard method. Thermal behavior of the HBPE-St was analyzed by using thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. The coatings of HBPE-St were prepared on mild steel strips. The anticorrosive behavior of HBPE-St resin-based coatings in acid, saline, and tap water was evaluated, and the molecular weight of HBPE-St was determined by gel permeation chromatography (GPC. The antibacterial activities of the HBPE-St copolymers were tested in vitro against bacteria and fungi by disc diffusion method. The HBPE-St copolymers exhibited good antibacterial activities and can be used as antimicrobial and corrosion-resistant coating materials.

  5. Irradiation of fresh fish

    Science.gov (United States)

    Yueh-jen, Yen; Jin-lai, Zhou; Shao-chun, Lai

    Occasionally, in China, marine products can not be provided for the markets in good quality, for during the time when they are being transported from the sea port to inland towns or even at the time when they are unloaded from the ship, they are beginning to spoil. Obviously, it is very important that appropiate measures should be taken to prevent them from decay. Our study has proved that the shelf life of fresh Flatfish (Cynoglossue robustus) and Silvery pomfret (stromateoides argenteus), which, packed in sealed containers, are irradiated by 1.5 kGy, 2.2 kGy and 3.0 kGy, can be stored for about 13-26 days at 3° - 5° C.

  6. Simultaneous determination of the styrene unit content and assessment of molecular weight of triblock copolymers in adhesives by a size exclusion chromatography method.

    Science.gov (United States)

    Wang, Mingfang; Wang, Yuerong; Luo, Pei; Zhang, Hongyang; Zhang, Min; Hu, Ping

    2017-10-01

    The content of styrene units in nonhydrogenated and hydrogenated styrene-butadiene-styrene and styrene-isoprene-styrene triblock copolymers significantly influences product performance. A size exclusion chromatography method was developed to determine the average styrene content of triblock copolymers blended with tackifier in adhesives. A complete separation of the triblock copolymer from the other additives was realized with size exclusion chromatography. The peak area ratio of the UV and refraction index signals of the copolymers at the same effective elution volume was correlated to the average styrene unit content using nuclear magnetic resonance spectroscopy with commercial copolymers as standards. The obtained calibration curves showed good linearity for both the hydrogenated and nonhydrogenated styrene-butadiene-styrene and styrene-isoprene-styrene triblock copolymers (r = 0.974 for styrene contents of 19.3-46.3% for nonhydrogenated ones and r = 0.970 for the styrene contents of 23-58.2% for hydrogenated ones). For copolymer blends, the developed method provided more accurate average styrene unit contents than nuclear magnetic resonance spectroscopy provided. These results were validated using two known copolymer blends consisting of either styrene-isoprene-styrene or hydrogenated styrene-butadiene-styrene and a hydrocarbon tackifying resin as well as an unknown adhesive with styrene-butadiene-styrene and an aromatic tackifying resin. The methodology can be readily applied to styrene-containing polymers in blends such as poly(acrylonitrile-butadiene styrene). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. The tonotopicity of styrene-induced hearing loss depends on the associated noise spectrum.

    Science.gov (United States)

    Venet, Thomas; Campo, Pierre; Thomas, Aurélie; Cour, Chantal; Rieger, Benoît; Cosnier, Frédéric

    2015-01-01

    The neuropharmacological and cochleotoxic effects of styrene can exacerbate the impact of noise on the peripheral auditory receptor. The mechanisms through which co-exposure to noise and styrene impairs hearing are complex as the slowly developing cochleotoxic process can be masked in the short-term by the rapid pharmacological effect on the central nervous system. The current investigation was therefore designed to delineate the auditory frequency range sensitive to noise, to styrene, and to noise and styrene combined. In case of different frequency ranges targeted by noise and styrene, it would be possible to point out the main factor responsible for cases of deafness by looking at the location of the audiometric deficits. Male Brown-Norway rats were exposed to 600-ppm styrene, to an octave band noise centered at 8 kHz, or to both noise and styrene. The noise exposure was of two different types: impulse noise with a LEX,8h (equivalent continuous noise level averaged over 8 h) of 80 dB and continuous noise with a LEX,8 h of 85 dB SPL. Hearing was tested using a non-invasive technique based on distortion product otoacoustic emissions. Hearing data were completed with histological analysis of cochleae. The results showed that exposure to styrene alone caused outer hair cell losses in the apical cochlear region, which discriminates low frequencies. In contrast, noise-induced hearing loss was located at half an octave above the central frequency of the spectrum, around 10-12 kHz. Damage due to impulse noise was significantly exacerbated by styrene, and the noise spectrum defined the location of the cochlear trauma. Combined exposure caused greater cell losses than the sum of losses measured with the impulse noise and styrene alone. The fact that the tonotopicity of the styrene-induced damage depends on the associated noise spectrum complicates the diagnosis of styrene-related hearing loss with a tone-frequency audiometric approach. In conclusion, there is not really a

  8. SYNTHESIS OF STYRENE-BUTADIENE STATISTIC COPOLYMERS CONTAINING MAGNESIUM INITIATOR

    Directory of Open Access Journals (Sweden)

    A. V. Firsova

    2015-01-01

    Full Text Available The article discusses the use of organomagnesium initiators in the synthesis of styrene-butadiene random copolymer (SBR obtained solution polymerization and their influence on the properties of rubber. Selected organic magnesium dialkyl initiator is combined with a modifier, which is a mixed alkoxide of an alkali and alkaline earth metals, which allows to control the micr ostructure of the diene polymer and its molecular weight characteristics. Alcohol derivatives selected high-boiling alcohols tetra (hydroxypropyl ethylenediamine (lapromol 294 and tetrahydrofurfuryl alcohol (TGFS. Selection of high-boiling alcohols due to the fact that the destruction of alkoxide with aqueous polymer degassing they do not fall into the return solvent and almost fall into the exact water. The metal components of alkoxides are lithium, sodium, potassium, magnesium and calcium. The resulting solutions are stable when stored modifier t hroughout the year even at -40 °C. The scheme of obtaining the new catalyst systems based organomagnesium and alcoxide of alkali and alkaline earth metals, which yields as functionalized SBR with a statistical and a distribution block of butadiene and styrene was developed. The process of copolymerization with styrene to butadiene organomagnesium initiators as using an organolithium compound (n-butyllithium was carried out, and without it. Found that the addition of n-butyllithium in the reaction mixture leads to a sharp increase in the rate of reaction. The results of studies of the effect of composition of the initiator system on the structure of diene polymers. It was revealed that a mixed initiator system affords a high conversion of monomers (to 90 % in 1 hour 1,2-polybutadiene content increased to 60 %. The process of polymerization of only a mixture of organomagnesium initiators and alcoxide of alkali and alkaline earth metals are not actively proceeds, conversion of the monomers reaches to 90 % in 4 hours, the microstructure

  9. Low level occupational exposure to styrene: its effects on DNA damage and DNA repair.

    Science.gov (United States)

    Wongvijitsuk, Sirilak; Navasumrit, Panida; Vattanasit, Udomratana; Parnlob, Varabhorn; Ruchirawat, Mathuros

    2011-03-01

    The present study aimed to evaluate the effects of styrene exposure at levels below the recommended standards of the Threshold Limit Value (TLV-TWA(8)) of 20 ppm (ACGIH, 2004) in reinforced-fiberglass plastics workers. Study subjects comprised 50 exposed workers and 40 control subjects. The exposed workers were stratified by styrene exposure levels, i.e. group I (20 ppm, >84.40 mg/m(3)). The mean styrene exposure levels of exposed workers were significantly higher than those of the control workers. Biomarkers of exposure to styrene, including blood styrene and the urinary metabolites, mandelic acid (MA) and phenylglyoxylic acid (PGA), were significantly increased with increasing levels of styrene exposure, but were not detected in the control group. DNA damage, such as DNA strand breaks, 8-hydroxydeoxyguanosine (8-OHdG), and DNA repair capacity, were used as biomarkers of early biological effects. DNA strand breaks and 8-OHdG/10(5)dG levels in peripheral leukocytes of exposed groups were significantly higher compared to the control group (Prisk from occupational styrene exposure, even at levels below the recommended TLV-TWA(8) of 20 ppm. Copyright © 2010 Elsevier GmbH. All rights reserved.

  10. A multicenter study on the audiometric findings of styrene-exposed workers.

    Science.gov (United States)

    Morata, Thais C; Sliwinska-Kowalska, Mariola; Johnson, Ann-Christin; Starck, Jukka; Pawlas, Krystyna; Zamyslowska-Szmytke, Ewa; Nylen, Per; Toppila, Esko; Krieg, Edward; Pawlas, Natalia; Prasher, Deepak

    2011-10-01

    The objective of this study was to evaluate hearing loss among workers exposed to styrene, alone or with noise. This cross-sectional study was conducted as part of NoiseChem, a European Commission 5th Framework Programme research project, by occupational health institutes in Finland, Sweden, and Poland. Participants' ages ranged from 18-72 years (n = 1620 workers). Participants exposed to styrene, alone or with noise, were from reinforced fiberglass products manufacturing plants (n = 862). Comparison groups were comprised of workers noise-exposed (n = 400) or controls (n = 358). Current styrene exposures ranged from 0 to 309 mg/m(3), while mean current noise levels ranged from 70-84 dB(A). Hearing thresholds of styrene-exposed participants were compared with Annexes A and B from ANSI S3.44, 1996. The audiometric thresholds of styrene exposed workers were significantly poorer than those in published standards. Age, gender, and styrene exposure met the significance level criterion in the multiple logistic regression for the binary outcome 'hearing loss' (P = 0.0000). Exposure to noise (risk factor for hearing loss, and styrene-exposed workers should be included in hearing loss prevention programs.

  11. Leaching of styrene and other aromatic compounds in drinking water from PS bottles.

    Science.gov (United States)

    Ahmad, Maqbool; Bajahlan, Ahmad S

    2007-01-01

    Bottled water may not be safer, or healthier, than tap water. The present studies have proved that styrene and some other aromatic compounds leach continuously from polystyrene (PS) bottles used locally for packaging. Water sapmles in contact with PS were extracted by a preconcentration technique called as "purge and trap" and analysed by gas chromatograph-mass spectrometer (GC/MS). Eleven aromatic compounds were identified in these studies. Maximum concentration of styrene in PS bottles was 29.5 microg/L. Apart from styrene, ethyl benzene, toluene and benzene were also quantified but their concentrations were much less than WHO guide line values. All other compounds were in traces. Quality of plastic and storage time were the major factor in leaching of styrene. Concentration of styrene was increased to 69.53 microg/L after one-year storage. In Styrofoam and PS cups studies, hot water was found to be contaminated with styrene and other aromatic compounds. It was observed that temperature played a major role in the leaching of styrene monomer from Styrofoam cups. Paper cups were found to be safe for hot drinks.

  12. Technoeconomic evaluation of bio-based styrene production by engineered Escherichia coli.

    Science.gov (United States)

    Claypool, Joshua T; Raman, D Raj; Jarboe, Laura R; Nielsen, David R

    2014-08-01

    Styrene is an important commodity chemical used in polymers and resins, and is typically produced from the petrochemical feedstocks benzene and ethylene. Styrene has recently been produced biosynthetically for the first time using engineered Escherichia coli, and this bio-based route may represent a lower energy and renewable alternative to petroleum-derived styrene. However, the economics of such an approach has not yet been investigated. Using an early-stage technoeconomic evaluation tool, a preliminary economic analysis of bio-based styrene from C(6)-sugar feedstock has been conducted. Owing to styrene's limited water solubility, it was assumed that the resulting fermentation broth would spontaneously form two immiscible liquid phases that could subsequently be decanted. Assuming current C(6) sugar prices and industrially achievable biokinetic parameter values (e.g., product yield, specific growth rate), commercial-scale bio-based styrene has a minimum estimated selling price (MESP) of 1.90 USD kg(-1) which is in the range of current styrene prices. A Monte Carlo analysis revealed a potentially large (0.45 USD kg(-1)) standard deviation in the MESP, while a sensitivity analysis showed feedstock price and overall yield as primary drivers of MESP.

  13. Mechanical and Thermal Properties of Styrene Butadiene Rubber - Functionalized Carbon Nanotubes Nanocomposites

    KAUST Repository

    Laoui, Tahar

    2013-01-01

    The effect of reinforcing styrene butadiene rubber (SBR) with functionalized carbon nanotubes on the mechanical and thermal properties of the nanocomposite was investigated. Multi-walled carbon nanotubes (CNTs) were functionalized with phenol functional group to enhance their dispersion in SBR matrix. Surface functionalization of the CNTs was carried out using acid treatment and FTIR technique was utilized so as to ascertain the presence of phenol functional group. This was followed with the dispersion of the functionalized CNTs into a polymer solution and a subsequent evaporation of the solvent. This study has demonstrated the inherent capability of CNTs as reinforcing filler as demonstrated by the substantial improvement in Young\\'s Modulus, tensile strength and energy of absorption of the nanocomposites. The tensile strength increased from 0.17 MPa (SBR) to 0.48 MPa while the Young\\'s Modulus increased from 0.25 MPa to 0.83 MPa when 10wt% functionalized CNTs was added. With the addition of 1wt% reinforcement-a peak value of 4.1 KJ energy absorption was obtained. The homogenous dispersion of CNT-Phenol is thought to be responsible for the considerable enhancement in the reported properties. Copyright © Taylor & Francis Group, LLC.

  14. Thermal Stability and Flammability of Styrene-Butadiene Rubber-Based (SBR Ceramifiable Composites

    Directory of Open Access Journals (Sweden)

    Rafał Anyszka

    2016-07-01

    Full Text Available Ceramifiable styrene-butadiene (SBR-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers (halloysite, calcined kaolin, mica or wollastonite and a sulfur-based curing system were prepared. Kinetics of vulcanization and basic mechanical properties were analyzed and added as Supplementary Materials. Combustibility of the composites was measured by means of cone calorimetry. Their thermal properties were analyzed by means of thermogravimetry and specific heat capacity determination. Activation energy of thermal decomposition was calculated using the Flynn-Wall-Ozawa method. Finally, compression strength of the composites after ceramification was measured and their micromorphology was studied by scanning electron microscopy. The addition of a ceramification-facilitating system resulted in the lowering of combustibility and significant improvement of the thermal stability of the composites. Moreover, the compression strength of the mineral structure formed after ceramification is considerably high. The most promising refractory fillers for SBR-based ceramifiable composites are mica and halloysite.

  15. Thermal Stability and Flammability of Styrene-Butadiene Rubber-Based (SBR) Ceramifiable Composites

    Science.gov (United States)

    Anyszka, Rafał; Bieliński, Dariusz M.; Pędzich, Zbigniew; Rybiński, Przemysław; Imiela, Mateusz; Siciński, Mariusz; Zarzecka-Napierała, Magdalena; Gozdek, Tomasz; Rutkowski, Paweł

    2016-01-01

    Ceramifiable styrene-butadiene (SBR)-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers (halloysite, calcined kaolin, mica or wollastonite) and a sulfur-based curing system were prepared. Kinetics of vulcanization and basic mechanical properties were analyzed and added as Supplementary Materials. Combustibility of the composites was measured by means of cone calorimetry. Their thermal properties were analyzed by means of thermogravimetry and specific heat capacity determination. Activation energy of thermal decomposition was calculated using the Flynn-Wall-Ozawa method. Finally, compression strength of the composites after ceramification was measured and their micromorphology was studied by scanning electron microscopy. The addition of a ceramification-facilitating system resulted in the lowering of combustibility and significant improvement of the thermal stability of the composites. Moreover, the compression strength of the mineral structure formed after ceramification is considerably high. The most promising refractory fillers for SBR-based ceramifiable composites are mica and halloysite. PMID:28773726

  16. Microstructural analysis of carbon nanomaterials produced from pyrolysis/combustion of Styrene-Butadiene-Rubber (SBR

    Directory of Open Access Journals (Sweden)

    Joner Oliveira Alves

    2011-12-01

    Full Text Available Styrene-Butadiene-Rubber (SBR is a synthetic rubber copolymer used to fabricate several products. This study aims to demonstrate the use of SBR as feedstock for carbon nanomaterials (nanofibers and nanotubes growth, and therefore to establish a novel process for destination of waste products containing SBR. A three stage electrically heated flow reactor was used. Small pellets of rubber were pyrolyzed at a temperature of 1000 ºC. The pyrolyzates were mixed with oxygen-containing gases and were burned. The products of combustion were used to synthesize the carbon nanomaterials (CNMs at the presence of a catalyst. CNMs have a wide range of potential applications due to their extraordinary mechanical, thermal and electrical properties. Produced materials were characterized by SEM and TEM, whereas combustion products were assessed using GC. Results showed that CNMs with outer diameters of 30-100 nm and lengths of about 30 µm were formed. Therefore, it was demonstrated that waste products containing SBR can be used to generate CNMs which are value-added products of intense technological interest.

  17. Performance of Styrene Butadiene Rubber as a Concrete Repair Material in tropical climate

    Science.gov (United States)

    Radhakrishnan, R.; Prakash, V. Syam; Thampan, C. K.; Varma, Prasad

    2012-11-01

    Deterioration of Concrete due to variety of reasons like corrosion of steel, inferior quality of materials as well as workmanship and exposure to aggressive environment like thermal cycling affect the performance or damage a number of Reinforced cement concrete structures. In order to repair these structures for enhancing the service life, number of methods and materials are available. But the degree of success of any repair in concrete depends mainly on the correct choice and the method of application of repair materials. This paper discusses the details of an experimental investigation on the performance of Styrene ñ Butadiene Rubber (SBR) as a concrete repair material in tropical climatic conditions. Resistance to water penetration and tensile cracking are two important performance criteria for any repair material. Cement mortar cubes of mix proportion 1:3 with SBR added at the rate of 20% of the weight of cement, and control specimens without SBR were made. Compressive strength and sorptivity values of the cubes were determined. Shear Bond strength (by slant shear test) and splitting tensile strength of the repaired cylinder specimens of standard dimensions, in which SBR used as a bonding agent were determined. These values were compared with the values obtained for the similar specimens, in which the bonding agent applied was conventional cement slurry. The influence of thermal cycling on the properties of repaired concrete specimens were also studied. A comparison has also been made with the values required to meet the standard specifications of a repair material.

  18. Trends in occupational exposure to styrene in the European glass fibre-reinforced plastics industry.

    Science.gov (United States)

    Van Rooij, J G M; Kasper, A; Triebig, G; Werner, P; Jongeneelen, F J; Kromhout, H

    2008-07-01

    This study presents temporal trends of styrene exposure for workers in the European glass fibre-reinforced plastics (GRP) industry during the period 1966-2002. Data of personal styrene exposure measurements were retrieved from reports, databases and peer-reviewed papers. Only sources with descriptive statistics of personal measurements were accepted. The styrene exposure data cover personal air samples and biological monitoring data, that is, urinary styrene metabolites (mandelic acid and/or phenylglyoxylic acid) and styrene in blood. Means of series of measurements were categorized by year, country, production process, job and sampling strategy. Linear mixed models were used to identify temporal trends and factors affecting exposure levels. Personal exposure measurements were available from 60 reports providing data on 24145 1-8-h time-weighted average shift personal air samples. Available data of biological exposure indicators included measurements of mandelic acid in post-shift urine (6361 urine samples being analysed). Trend analyses of the available styrene exposure data showed that the average styrene concentration in the breathing zone of open-mould workers in the European GRP industry has decreased on average by 5.3% per year during the period 1966-1990 and by only 0.4% annually in the period after 1990. The highest exposures were measured in Southern Europe and the lowest exposures in Northern Europe with Central Europe in between. Biological indicators of styrene (mandelic acid in post-shift urine) showed a somewhat steeper decline (8.9%), most likely because urine samples were collected in companies that showed a stronger decrease of styrene exposure in air than GRP companies where no biological measurements were carried out.

  19. Synthesis of hollow silver spheres using poly-(styrene-methyl acrylic acid) as templates in the presence of sodium polyacrylate

    Science.gov (United States)

    Wang, Aili; Yin, Hengbo; Ge, Chen; Ren, Min; Liu, Yumin; Jiang, Tingshun

    2010-02-01

    Hollow silver spheres were successfully prepared by reducing AgNO 3 with ascorbic acid and using negatively charged poly-(styrene-methyl acrylic acid) (PSA) spheres as templates in the presence of sodium polyacrylate as a stabilizer. Firstly, silver cations adsorbed on the surface of PSA spheres via electrostatic attraction between the carboxyl groups and silver cations were reduced in situ by ascorbic acid. The silver nanoparticles deposited on the surface of PSA spheres served as seeds for the further growth of silver shells. After that, extra amount of AgNO 3 and ascorbic acid solutions were added to form PSA/Ag composites with thick silver shells. In order to obtain compact silver shells, the as-prepared PSA/Ag composites were heated at 150 °C for 3 h. Then hollow silver spheres were prepared by dissolving PSA templates with tetrahydrofuran.

  20. Microbiota analysis to reveal temperature abuse of fresh pork

    DEFF Research Database (Denmark)

    Buschhardt, Tasja; Bahl, Martin Iain; Hansen, Tina Beck

    whether temperature induced changes in the community composition on fresh meat surfaces can reflect the temperature-history (combination of time and temperature). Sterile pieces of pork were inoculated with a carcass swab homogenate, to which Salmonella was added. Changes in the meat microbiota were...

  1. Microbiota analysis to reveal temperature abuse of fresh pork

    DEFF Research Database (Denmark)

    Buschhardt, Tasja; Bahl, Martin Iain; Hansen, Tina Beck

    2017-01-01

    whether temperature induced changes in the community composition on fresh meat surfaces can reflect the temperature-history (combination of time and temperature). Sterile pieces of pork were inoculated with a carcass swab homogenate, to which Salmonella was added. Changes in the meat microbiota were...

  2. Simulation of styrene polymerization reactors: kinetic and thermodynamic modeling

    Directory of Open Access Journals (Sweden)

    A. S. Almeida

    2008-06-01

    Full Text Available A mathematical model for the free radical polymerization of styrene is developed to predict the steady-state and dynamic behavior of a continuous process. Special emphasis is given for the kinetic and thermodynamic models, where the most sensitive parameters were estimated using data from an industrial plant. The thermodynamic model is based on a cubic equation of state and a mixing rule applied to the low-pressure vapor-liquid equilibrium of polymeric solutions, suitable for modeling the auto-refrigerated polymerization reactors, which use the vaporization rate to remove the reaction heat from the exothermic reactions. The simulation results show the high predictive capability of the proposed model when compared with plant data for conversion, average molecular weights, polydispersity, melt flow index, and thermal properties for different polymer grades.

  3. Preparation of acrylonitrile butadiene styrene fibers by pulse electrospinning

    Directory of Open Access Journals (Sweden)

    Dilyara Igimbayeva

    2014-12-01

    Full Text Available The paper represents the results on the preparation of polymer fibers of acrylonitrile butadiene styrene (ABS with the addition of iron as a modifying additives by pulse electrospinning. The virtue of the method of pulse electrospinning in comparison with classical electrospinning is to obtain fibers with a controlled length. To study the morphology of the fibers obtained samples were used the optical and scanning electron microscopy. To prove the presence of iron inside the fibers methods of elemental analysis and electron paramagnetic resonance were used. The technique and optimal conditions for obtaining fibers have been determined. The effect of technological parameters, concentrations of polymer solutions and modifying additives on the structure and morphology of the fibers were shown.

  4. Interacting Blends of Novel Unsaturated Polyester Amide Resin with Styrene

    Directory of Open Access Journals (Sweden)

    Hasmukh S. Patel

    2004-01-01

    Full Text Available Novel unsaturated poly (ester-amide resins (UPEAs were prepared by the reaction between an epoxy resin, namely diglycidyl ether of bisphenol–A (DGEBA and unsaturated aliphatic bisamic acids using a base catalyst. These UPEAs were then blended with a vinyl monomer namely, Styrene (STY. to produce a homogeneous resin syrup. The curing of these UPEAs-STY. resin blends was carried out by using benzoyl peroxide (BPO as a catalyst and was monitored by using a differential scanning calorimeter (DSC. The glass fibre reinforced composites (i.e. laminates of these UPEA-STY. resin blends were fabricated using the DSC data. The chemical, mechanical and electrical properties of the glass fibre composites have also been evaluated. The unreinforced cured samples of the UPEA-STY. resin blends were also analyzed by thermogravimetry (TGA.

  5. Impaired colour discrimination among workers exposed to styrene: relevance of a urinary metabolite.

    OpenAIRE

    Eguchi, T.; Kishi, R.; Harabuchi, I; Yuasa, J; Arata, Y; Katakura, Y; Miyake, H.

    1995-01-01

    OBJECTIVES--To survey the loss of colour vision among Japanese workers who have been exposed to styrene concentrations currently considered low (about 20 ppm). Also to assess the effects of styrene by examination of the nature of the relation between disorder of colour vision and age, alcohol consumption, and other variables. METHODS--Colour discrimination was examined in 64 male workers exposed to styrene (mean age; 38.0, mean exposed years; 7.0) and in 69 controls (mean age; 38.0). A standa...

  6. Axion wormholes in AdS compactifications

    Science.gov (United States)

    Hertog, Thomas; Trigiante, Mario; Van Riet, Thomas

    2017-06-01

    We find regular axionic Euclidean wormhole solutions in Type IIB string theory compactified on {AdS}_5× {S}^5/{Z}_k . AdS/CFT enables a precise derivation of the axion content of the Euclidean theory, placing the string theory embedding of the wormholes on firm footing. This further sharpens the paradox posed by these solutions.

  7. Base isolation: Fresh insight

    Energy Technology Data Exchange (ETDEWEB)

    Shustov, V.

    1993-07-15

    The objective of the research is a further development of the engineering concept of seismic isolation. Neglecting the transient stage of seismic loading results in a widespread misjudgement: The force of resistance associated with velocity is mostly conceived as a source of damping vibrations, though it is an active force at the same time, during an earthquake type excitation. For very pliant systems such as base isolated structures with relatively low bearing stiffness and with artificially added heavy damping mechanism, the so called `damping`` force may occur even the main pushing force at an earthquake. Thus, one of the two basic pillars of the common seismic isolation philosophy, namely, the doctrine of usefulness and necessity of a strong damping mechanism, is turning out to be a self-deception, sometimes even jeopardizing the safety of structures and discrediting the very idea of seismic isolation. There is a way out: breaking with damping dependancy.

  8. The influence of mechanical properties in the electrical breakdown in poly-styrene-ethylene-butadiene-styrene thermoplastic elastomer

    Science.gov (United States)

    Kollosche, Matthias; Melzer, Michael; Becker, Andre; Stoyanov, Hristian; McCarthy, Denis N.; Ragusch, Hülya; Kofod, Guggi

    2009-03-01

    Dielectric elastomer actuators (DEA) are a class of eletro-active polymers with promising properties for a number of applications, however, such actuators are prone to failure. One of the leading failure mechanisms is the electrical breakdown. It is already well-known that the electro-mechanical actuation properties of DEA are strongly influenced by the mechanical properties of the elastomer and compliant electrodes. It was recently suggested that also the electrical breakdown in such soft materials is influenced by the mechanical properties of the elastomer. Here, we present stress-strain measurements obtained on two tri-block thermoplastic elastomers (SEBS 500040 and SEBS 500120, poly-styrene-ethylene-butadiene-styrene), with resulting large differences in mechanical properties, and compare them to measurements on the commonly used VHB 4910. Materials were prepared by either direct heat-pressing of the raw material, or by dissolving in toluene, centrifuging and drop-casting. Experiments showed that materials prepared with identical processing steps showed a difference in stiffness of about 20%, where centrifuged and drop-casted films were seen to be softer than heat-pressed films. Electric breakdown measurements showed that for identically processed materials, the stiffness seemed to be a strong indicator of the electrical breakdown strength. It was therefore found that processing leads to differences in both stiffness and electrical breakdown strength. However, unexpectedly, the softer drop-cast films had a much higher breakdown strength than the heatpressed films. We attribute this effect to impurities still present in the heat-pressed films, since these were not purified by centrifuging.

  9. 76 FR 15225 - Importation of Fresh Baby Kiwi From Chile Under a Systems Approach

    Science.gov (United States)

    2011-03-21

    ... Animal and Plant Health Inspection Service 7 CFR Part 319 RIN 0579-AD37 Importation of Fresh Baby Kiwi... importation into the continental United States of baby kiwi fruit from Chile, subject to a systems approach... packinghouse inspections. This proposed rule would allow for the safe importation of fresh baby kiwi from Chile...

  10. Timescales of AMOC decline in response to fresh water forcing

    Science.gov (United States)

    Jackson, Laura C.; Wood, Richard A.

    2017-12-01

    The Atlantic meridional overturning circulation (AMOC) is predicted to weaken over the coming century due to warming from greenhouse gases and increased input of fresh water into the North Atlantic, however there is considerable uncertainty as to the amount and rate of AMOC weakening. Understanding what controls the rate and timescale of AMOC weakening may help to reduce this uncertainty and hence reduce the uncertainty surrounding associated impacts. As a first step towards this we consider the timescales associated with weakening in response to idealized freshening scenarios. Here we explore timescales of AMOC weakening in response to a freshening of the North Atlantic in a suite of experiments with an eddy-permitting global climate model (GCM). When the rate of fresh water added to the North Atlantic is small (0.1 Sv; 1 Sv =1× 10^6 m^3 /s), the timescale of AMOC weakening depends mainly on the rate of fresh water input itself and can be longer than a century. When the rate of fresh water added is large (≥ 0.3 Sv) however, the timescale is a few decades and is insensitive to the actual rate of fresh water input. This insensitivity is because with a greater rate of fresh water input the advective feedbacks become more important at exporting fresh anomalies, so the rate of freshening is similar. We find advective feedbacks from: an export of fresh anomalies by the mean flow; less volume import through the Bering Strait; a weakening AMOC transporting less subtropical water northwards; and anomalous subtropical circulations which amplify export of the fresh anomalies. This latter circulation change is driven itself by the presence of fresh anomalies exported from the subpolar gyre through geostrophy. This feedback has not been identified in previous model studies and when the rate of freshening is strong it is found to dominate the total export of fresh anomalies, and hence the timescale of AMOC decline. Although results may be model dependent, qualitatively

  11. In-situ Polymerization of Styrene to Produce Polystyrene / Montmorillonite Nanocomposites

    National Research Council Canada - National Science Library

    Lahouari Mrah; Rachid Meghabar; Mohammed Belbachir

    2015-01-01

    .... CTAB-intercalated Mmt particles were easily dispersed and swollen in styrene monomer, PS/Mmt-CTAB nanocomposites were synthesized via in-situ polymerization, in-situ polymerization, this method...

  12. Exposure to styrene in fiberglass-reinforced plastic manufacture: still a problem.

    Science.gov (United States)

    Papaleo, Bruno; Caporossi, Lidia; Bernardini, Francesca; Cristadoro, Luisa; Bastianini, Lucia; De Rosa, Mariangela; Capanna, Silvia; Marcellini, Laura; Loi, Francesco; Battista, Giuseppe

    2011-11-01

    The aim of the work is to define occupational exposure to styrene in fiberglass manufacture; the phase of stretching styrene resins needs some manual handling and leads workers to be exposed to styrene. We surveyed 20 workers in two companies manufacturing fiberglass, checking environmental levels and urinary concentrations of mandelic acid (MA), and phenylglioxylic acid (PGA). Workers completed a questionnaire collecting their medical history. Environmental monitoring showed some styrene concentrations higher than the threshold limit value-time-weighted average. Biological monitoring confirmed these findings and four workers had levels of urinary PGA and MA concentrations higher than the Biological Exposure Indices of the American Conference of Governmental Industrial Hygienists. This picture confirms that, even though the risk is known and the manufacturing cycle is well-defined, workers nevertheless risk exposure. More research is needed to optimize the work processes and the protection systems to lower this risk.

  13. Formation of styrene dependent on fermentation management during wheat beer production.

    Science.gov (United States)

    Schwarz, Katrin J; Stübner, René; Methner, Frank-Jürgen

    2012-10-15

    Styrene is formed by the thermal decarboxylation of cinnamic acid during wort boiling or by enzymatic decarboxylation during fermentation. The enzymatic reactions proceed in parallel to the decarboxylation of ferulic- and p-cumaric acid to 4-vinylguaiacol and 4-vinylphenol by the same decarboxylase enzyme. However, the formation of styrene occurs much faster and all available cinnamic acid in wort was converted completely within a few hours. Moreover, the comparison of various manufacturing parameters shows that a higher fermentation temperature of 25 °C compared to 16 °C and an open fermentation management lead to a rapid decrease of styrene. This allows minimising the content of styrene in beer while maintaining the typical wheat beer flavours. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Crack initiation and propagation on the polymeric material ABS (Acrylonitrile Butadiene Styrene), under ultrasonic fatigue testing

    National Research Council Canada - National Science Library

    G M Domínguez Almaraz; E Correa Gómez; JC Verduzco Juárez; JL Avila Ambriz

    2015-01-01

    ... (Acrylonitrile Butadiene Styrene), under ultrasonic fatigue testing. Three controlled actions were implemented in order to carry out fatigue tests at very high frequency on this material of low thermal conductivity, they are: a...

  15. EPR investigation on radiation-induced graft copolymerization of styrene onto polyethylene: Energy transfer effects

    Energy Technology Data Exchange (ETDEWEB)

    Salih, M.A. [Dipartimento di Chimica Generale, Universita di Pavia, 27100 Pavia (Italy); Buttafava, A. [Dipartimento di Chimica Generale, Universita di Pavia, 27100 Pavia (Italy); Ravasio, U. [Dipartimento di Chimica Generale, Universita di Pavia, 27100 Pavia (Italy); Dipartimento di Ingegneria Nucleare, Politecnico di Milan (Italy); Mariani, M. [Dipartimento di Ingegneria Nucleare, Politecnico di Milan (Italy); Faucitano, A. [Dipartimento di Chimica Generale, Universita di Pavia, 27100 Pavia (Italy)]. E-mail: antonio.faucitano@unipv.it

    2007-08-15

    In this paper, energy transfer phenomena concerning the in-source graft copolymerization of styrene onto LDPE were investigated through the EPR analysis of the radical intermediates. The model solution experiments have shown a substantial deviation of the experimental G (radicals) values with respect to the additivity law, which reflect the negative effect of the styrene monomer concentration on the initiation rate of the graft copolymerization. The EPR measurements performed on polyethylene-co-styrene graft copolymers of various composition following low-temperature vacuum gamma irradiation have confirmed the decrease of the total radical yields with increasing the styrene concentration. The effect was partly attributed to the heterogeneity of the graft copolymer matrix and to the lack of molecular mobility in the solid state at low temperature, which prevents the attainment of the favourable geometrical configurations in intermolecular energy and charge transfer events.

  16. Updated evaluation of the migration of styrene monomer and oligomers from polystyrene food contact materials to foods and food simulants.

    Science.gov (United States)

    Genualdi, Susan; Nyman, Patricia; Begley, Timothy

    2014-04-01

    Due to the 2011 labelling of styrene monomer as "reasonably anticipated to be a human carcinogen" by the National Institutes of Health's National Toxicology Program (NTP) and the controversy over whether styrene oligomers mimic the physiological effects of estrogen, an updated review of styrene monomer and oligomers in food and food contact materials (FCMs) was performed. The concentrations of styrene monomer and oligomers were determined in 24 polystyrene (PS) products and ranged from 9.3 to 3100 mg kg(-1) for the styrene monomer, 130-2900 mg kg(-1) for the sum of three styrene dimers, and 220-16,000 mg kg(-1) for the sum of six styrene trimers. Foods in contact with PS packaging had styrene monomer concentrations ranging from 2.6 to 163 ng g(-1); dimer concentrations from the limit of quantitation (LOQ) to 4.8 ng g(-1) and trimer concentrations were all below the LOQ (2 ng g(-1)). Diffusion coefficients (Dp) and partition coefficients (K) were also calculated for styrene dimers and trimers. The results presented here indicate that styrene monomer concentrations in foods have not significantly changed since the 1980s and monomer concentrations in food packaging quantified in this study were all below USFDA limits. Although styrene dimers and trimers are present in higher concentrations in PS FCMs than the monomer, their migration to food is limited because of their high K values (4 × 10(2) to 2 × 10(6)) and their low diffusion coefficients in PS products. Additionally, diffusion coefficients calculated using USFDA-recommended food simulants and Arrhenius plots describing the temperature dependence of styrene dimers and trimers can be used in future calculations of dietary intake of the styrene oligomers.

  17. Poly(styrene-co-divinylbenzene-co-2-ethylhexyl)acrilate membranes with interconnected macroporous structure

    OpenAIRE

    Sevšek, Urška; Stropnik, Črtomir; Krajnc, Peter; Pulko, Irena; Seifried, Silvo

    2015-01-01

    A combination of doctor blading and emulsion templating was used to prepare macroporous poly(styrene-co-divinylbenzene-co-2-ethylhexylacrylate) and poly(styrene-co-divinylbenzene) membranes with an interconnected porous structure. Water in oil high internal phase emulsions including monomers in the oil phase were cast onto a glass plate and polymerised at elevated temperature. After purification porous polyHIPE membranes were obtained. The volume ratio of aqueous phase (75 % or 85 %) and the ...

  18. Impact behaviour of acrylonitrile-butadiene-styrene after temperature and humidity load

    OpenAIRE

    Hylova Lenka; Manas Miroslav

    2017-01-01

    This study deals with acrylonitrile-butadiene-styrene (ABS) which was subjected the drop-weight test before and after temperature and humidity load. ABS is an engineering plastic and also an important engineering terpolymer, which has butadiene part uniformly distributed through the acrylonitrile-styrene matrix and is commonly used in production of automotive interior components. The injection moulded ABS samples were subjected the penetration test at fall height 100 J before and after temper...

  19. Genotoxicity of styrene oligomers extracted from polystyrene intended for use in contact with food

    Directory of Open Access Journals (Sweden)

    Makoto Nakai

    2014-01-01

    Full Text Available Here, we conducted in vitro genotoxicity tests to evaluate the genotoxicity of styrene oligomers extracted from polystyrene intended for use in contact with food. Styrene oligomers were extracted with acetone and the extract was subjected to the Ames test (OECD test guideline No. 471 and the in vitro chromosomal aberration test (OECD test guideline No. 473 under good laboratory practice conditions. The concentrations of styrene dimers and trimers in the concentrated extract were 540 and 13,431 ppm, respectively. Extraction with acetone provided markedly higher concentrations of styrene oligomers compared with extraction with 50% ethanol aqueous solution, which is the food simulant currently recommended for use in safety assessments of polystyrene by both the United States Food and Drug Administration and the European Food Safety Authority. And these high concentrations of styrene dimers and trimers were utilized for the evaluation of genotoxicity in vitro. Ames tests using five bacterial tester strains were negative both in the presence or absence of metabolic activation. The in vitro chromosomal aberration test using Chinese hamster lung cells (CHL/IU was also negative. Together, these results suggest that the risk of the genotoxicity of styrene oligomers that migrate from polystyrene food packaging into food is very low.

  20. Influence of morphology on electrical breakdown characteristics of ethylen-styrene copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Masaaki; Matsuo, Katsuya; Oki, Yoshimichi; Hozumi, Naohiro; Harashige, Masahiro

    1988-08-20

    For developing the insulating material of ethylene-styrene copolymer to be applicable to 500 Kv electric cable, a study was conducted on the relation between higher order molecular structure and breakdown characteristics of insulator. The experiment was composed of measurement of intensity of electric field at breakdown, of its dependency on the wave shape of voltage, of melting behavior of crystal by differential scanning calorimeter, of degree of crystallinity by x-ray diffraction, and of the observation by transmission type electronic microscope. As the result of experiment, dependency of crystallinity on styrene content, linear correlation of total absorbed heat with ethylene content, and of hardness and styrene content, were shown as graphs. Relation between the intensity of breakdown electric field and styrene content was approximated by two broken straight lines. As the consideration, it was obtained that the breakdown occurred at the weak point of polyethylene structure, that the intensity of breakdown electric field was increased proportionally with styrene content, and that, for achieving higher breakdown voltage by increasing the energy absorbing capacity of benzene ring, randomly copolymerized copolymer with uniform dispersion of styrene molecule was better than graft polymer of the same components. (13 figs, 8 refs)

  1. Surface modification of poly(styrene-b-(ethylene-co-butylene)-b-styrene) elastomer via photo-initiated graft polymerization of poly(ethylene glycol)

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaomeng [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Luan Shifang, E-mail: sfluan@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yang Huawei; Shi Hengchong; Zhao Jie; Jin Jing [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yin Jinghua, E-mail: yinjh@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Stagnaro, Paola [Istituto per Io Studio delle Macromolecole, Consiglio Nazionale delle Ricerche, Via de Marini 6, 16149 Genova (Italy)

    2012-01-15

    Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) copolymer biomedical elastomer was covalently grafted with poly(ethylene glycol) methyl ether methacrylate (PEGMA) via a photo-initiated graft polymerization technique. The surface graft polymerization of SEBS with PEGMA was verified by ATR-FTIR and XPS. Effect of graft polymerization parameters, i.e., monomer concentration, UV irradiation time and initiator concentration on the grafting density was investigated. Comparing with the virgin SEBS film, the PEGMA-modified SEBS film presented an enhanced wettability and a larger surface energy. Besides, the surface grafting of PEGMA imparted excellent anti-platelet adhesion and anti-protein adsorption to the SEBS surface.

  2. Polarised Black Holes in AdS

    CERN Document Server

    Costa, Miguel S.; Oliveira, Miguel; Penedones, João; Santos, Jorge E.

    2016-05-03

    We consider solutions in Einstein-Maxwell theory with a negative cosmological constant that asymptote to global $AdS_{4}$ with conformal boundary $S^{2}\\times\\mathbb{R}_{t}$. At the sphere at infinity we turn on a space-dependent electrostatic potential, which does not destroy the asymptotic $AdS$ behaviour. For simplicity we focus on the case of a dipolar electrostatic potential. We find two new geometries: (i) an $AdS$ soliton that includes the full backreaction of the electric field on the $AdS$ geometry; (ii) a polarised neutral black hole that is deformed by the electric field, accumulating opposite charges in each hemisphere. For both geometries we study boundary data such as the charge density and the stress tensor. For the black hole we also study the horizon charge density and area, and further verify a Smarr formula. Then we consider this system at finite temperature and compute the Gibbs free energy for both $AdS$ soliton and black hole phases. The corresponding phase diagram generalizes the Hawkin...

  3. Unexpected differences between thermal and photoinitiated cationic curing of a diglycidyl ether of bisphenol A modified with a multiarm star poly(styrene-b-poly(ε-caprolactone polymer

    Directory of Open Access Journals (Sweden)

    J. M. Morancho

    2013-07-01

    Full Text Available The effect of adding a multiarm star poly(styrene-b-poly(ε-caprolactone polymer on the cationic thermal and photoinitiated curing of diglycidyl ether of bisphenol A was studied. This star-polymer decelerated the thermal curing of diglycidyl ether of bisphenol A and modified the final structure of the epoxy matrix. The photocuring was influenced significantly by the addition of the multiarm star. When the proportion of this modifier added was 5%, much more time was necessary for complete photocuring (160 min at 40ºC. In the presence of 10% of modifier, the degree of photocuring reached was very low (0.196 at 120°C. A subsequent thermal post-curing was necessary to cure completely the system. During photocuring in presence of poly(styrene-b-poly(ε-caprolactone, the formation of dormant species, which are reactivated when the temperature increases, takes places. The kinetics of the thermal curing and the photocuring was analyzed using an isoconversional method due to the complexity of the reactive process. Applying this method, it has been confirmed the dependence of activation energy on the degree of conversion. The fracture morphology analyzed by scanning electron microscopy exhibited a second phase originated during photocuring by the presence of the modifier.

  4. Study on Exothermic Oxidation of Acrylonitrile-butadiene-styrene (ABS Resin Powder with Application to ABS Processing Safety

    Directory of Open Access Journals (Sweden)

    Jenq-Renn Chen

    2010-08-01

    Full Text Available Oxidative degradation of commercial grade ABS (Acrylonitrile-butadiene-styrene resin powders was studied by thermal analysis. The instabilities of ABS containing different polybutadiene (PB contents with respect to temperature were studied by Differential Scanning Calorimeter (DSC. Thermograms of isothermal test and dynamic scanning were performed. Three exothermic peaks were observed and related to auto-oxidation, degradation and oxidative decomposition, respectively. Onset temperature of the auto-oxidation was determined to be around 193 °C. However, threshold temperature of oxidation was found to be as low as 140 °C by DSC isothermal testing. Another scan of the powder after degeneration in air showed an onset temperature of 127 °C. Reactive hazards of ABS powders were verified to be the exothermic oxidation of unsaturated PB domains, not the SAN (poly(styrene-acrylonitrile matrix. Heat of oxidation was first determined to be 2,800 ± 40 J per gram of ABS or 4,720 ± 20 J per gram of PB. Thermal hazards of processing ABS powder are assessed by adiabatic temperature rise at process conditions. IR spectroscopy associated with heat of oxidation verified the oxidative mechanism, and these evidences excluded the heat source from the degradation of SAN. A specially prepared powder of ABS without adding anti-oxidant was analyzed by DSC for comparing the exothermic behaviors. Exothermic onset temperatures were determined to be 120 °C and 80 °C by dynamic scanning and isothermal test, respectively. The assessment successfully explained fires and explosions in an ABS powder dryer and an ABS extruder.

  5. Controlled Release of Imidacloprid from Poly Styrene-Diacetone - Nanoformulation

    Science.gov (United States)

    Qian, Kun; Guo, Yanzhen; He, Lin

    2012-01-01

    Imidacloprid is a neonicotinoids insecticide, which is important for the cash crops such as tomato, rape and so on. The conventional formulation does not only increase the loss of pesticide but also leads to environmental pollution. Controlled-release formulations of pesticide are highly desirable not only for attaining the most effective utilization of the pesticide, but also for reducing environmental pollution. Pesticide imidacloprid was incorporated in poly (styrene-diacetone crylamide)-based formulation to obtain controlled release properties, and the imidacloprid nanocontrolled release formulation was characterized by infrared (IR) and field emission scanning electron microscope (FESEM). Factors related to loading efficiency, swelling and release behaviors of the formulation were investigated. It showed that the loading efficiency could reach about 40% (w/w). The values for the diffusion exponent "n" were in the range of 0.31-0.58, which indicated that the release of imidacloprid was diffusion-controlled. The time taken for 50% of the active ingredient to be released into water, T50, was also calculated for the comparison of formulations in different conditions. The results showed that the formulation with higher temperature and more diacetone crylamide had lower value of T50, which means a quicker release of the active ingredient. This study highlighted some pieces of evidence that improved pesticide incorporation and slower release were linked to potential interactions between the pesticide and the polymer.

  6. Fatigue Characteristics of 3D Printed Acrylonitrile Butadiene Styrene (ABS)

    Science.gov (United States)

    Padzi, M. M.; Bazin, M. M.; Muhamad, W. M. W.

    2017-11-01

    Recently, the use of 3D printer technology has become significant to industries, especially when involving the new product development. 3D printing is a technology, which produces the 3D product or prototype using a layer-by-layer technique. However, there becomes less research on the mechanical performance of the 3D printed component. In the present work, fatigue characteristics of 3D printed specimen have been studied. Acrylonitrile butadiene styrene (ABS) has been chosen as a material research due to its wide applications. Two types of specimen used, which is the 3D printing and moulding specimens. Fused deposition modelling (FDM) technique was used to produce the specimens. The dog bone shape part was produced based on ASTM D638 standard and the tensile test has been carried out to get the mechanical properties. Fatigue test was carried out at 40%, 60% and 80% of the tensile strength. The moulded part shows higher fatigue cycles compared to 3D printed part for all loading percentages. Fatigue lives for 40%, 60% and 80%, were 911, 2645 and 26948 cycles, respectively. The results indicated that 3D printed part has a lower fatigue life, which may not suitable for industrial applications. However, the 3D printed part could be improved by using various parameters and may be introduced in low strength application.

  7. Current status of AdS instability

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    arXiv:1403.6471 and thoroughly developed in arXiv:1407.6273. On the other hand the negative cosmological constant allows for the existence of stable, time-periodic, asymptotically AdS solutions of Einstein equations [arXiv:1303.3186].

  8. AdS braneworld with Backreaction

    CERN Document Server

    Bilic, Neven

    2014-01-01

    We review the tachyon model derived from the dynamics of a 3-brane moving in the AdS5 bulk. The bulk geometry is based on the Randall-Sundrum II model extended to include the radion. The effective tachyon Lagrangian is modified due to the back-reaction of the brane on the bulk geometry.

  9. In Situ Investigation of the Adsorption of Styrene Phosphonic Acid on Cassiterite (110) Surface by Molecular Modeling

    National Research Council Canada - National Science Library

    Guichen Gong; Yuexin Han; Jie Liu; Yimin Zhu; Yanfeng Li; Shuai Yuan

    2017-01-01

    The flotation, adsorption and bonding mechanisms of styrene phosphonic acid (SPA) to cassiterite were studied using microflotation tests, zeta potential measurements, solution chemistry analysis and density functional theory...

  10. Postharvest treatments of fresh produce

    Science.gov (United States)

    Mahajan, P. V.; Caleb, O. J.; Singh, Z.; Watkins, C. B.; Geyer, M.

    2014-01-01

    Postharvest technologies have allowed horticultural industries to meet the global demands of local and large-scale production and intercontinental distribution of fresh produce that have high nutritional and sensory quality. Harvested products are metabolically active, undergoing ripening and senescence processes that must be controlled to prolong postharvest quality. Inadequate management of these processes can result in major losses in nutritional and quality attributes, outbreaks of foodborne pathogens and financial loss for all players along the supply chain, from growers to consumers. Optimal postharvest treatments for fresh produce seek to slow down physiological processes of senescence and maturation, reduce/inhibit development of physiological disorders and minimize the risk of microbial growth and contamination. In addition to basic postharvest technologies of temperature management, an array of others have been developed including various physical (heat, irradiation and edible coatings), chemical (antimicrobials, antioxidants and anti-browning) and gaseous treatments. This article examines the current status on postharvest treatments of fresh produce and emerging technologies, such as plasma and ozone, that can be used to maintain quality, reduce losses and waste of fresh produce. It also highlights further research needed to increase our understanding of the dynamic response of fresh produce to various postharvest treatments. PMID:24797137

  11. Occupational exposure to styrene in the fibreglass reinforced plastic industry: comparison between two different manufacturing processes.

    Science.gov (United States)

    Tranfo, Giovanna; Gherardi, Monica; Paci, E; Gatto, Mariapia; Gordiani, A; Caporossi, Lidia; Capanna, Silvia; Sisto, Renata; Papaleo, B; Fiumalbi, Carla; Garofani, Patrizia

    2012-01-01

    Styrene is used in manufacturing fiberglass reinforced plastics: and occupational exposure was related to neurotoxicology and genotoxicity. The sum of the metabolites mandelic and phenylglyoxylic acids is the ACGIH biomarker for occupational exposure with a BEI of 400 mg/g of creatinine in end shift urine corresponding to a airborne styrene concentration of 85 mg/m3. There are two main molding processes, open and closed, the last more effective at controlling worker's styrene exposure. To compare the open molding process to the compression of fiber reinforced resin foils, a kind of closed molding, monitoring the styrene exposure of workers in two production sites (A and B). Environmental Monitoring was carried out by Radiello samplers and Biological Monitoring by means of the determination of MA and PGA with HPLC/MS/MS in 10 workers at Site A and 14 at Site B. The median values for styrene exposure resulted 31.1 mg/m3 for Site A and 24.4 mg/m for Site B, while the medians for the sum of the two metabolites in the end shift urine were 86.7 e 33.8 mg/g creatinine respectively. There is a significant linear correlation between personal styrene exposure and the excretion of styrene metabolites (R = 0.74). As expected the exposure markers of the workers of the two production sites resulted higher in the open process. The analytical results of both environmental and biological monitoring were all below the occupational exposure limits, confirming the efficacy of the protective devices.

  12. Lorentzian AdS, Wormholes and Holography

    CERN Document Server

    Arias, Raul E; Silva, Guillermo A

    2011-01-01

    We investigate the structure of two point functions for the QFT dual to an asymptotically Lorentzian AdS-wormhole. The bulk geometry is a solution of 5-dimensional second order Einstein Gauss Bonnet gravity and causally connects two asymptotically AdS space times. We revisit the GKPW prescription for computing two-point correlation functions for dual QFT operators O in Lorentzian signature and we propose to express the bulk fields in terms of the independent boundary values phi_0^\\pm at each of the two asymptotic AdS regions, along the way we exhibit how the ambiguity of normalizable modes in the bulk, related to initial and final states, show up in the computations. The independent boundary values are interpreted as sources for dual operators O^\\pm and we argue that, apart from the possibility of entanglement, there exists a coupling between the degrees of freedom leaving at each boundary. The AdS_(1+1) geometry is also discussed in view of its similar boundary structure. Based on the analysis, we propose a ...

  13. Baby Skyrmions in AdS

    Energy Technology Data Exchange (ETDEWEB)

    Elliot-Ripley, Matthew; Winyard, Thomas [Department of Mathematical Sciences, Durham University,South Rd, Durham (United Kingdom)

    2015-09-01

    We study the baby Skyrme model in a pure AdS background without a mass term. The tail decays and scalings of massless radial solutions are demonstrated to take a similar form to those of the massive flat space model, with the AdS curvature playing a similar role to the flat space pion mass. We also numerically find minimal energy solutions for a range of higher topological charges and find that they form concentric ring-like solutions. Popcorn transitions (named in analogy with studies of toy models of holographic QCD) from an n layer to an n+1-layer configuration are observed at topological charges 9 and 27 and further popcorn transitions for higher charges are predicted. Finally, a point-particle approximation for the model is derived and used to successfully predict the ring structures and popcorn transitions for higher charge solitons.

  14. Proton conducting sulphonated fluorinated poly(styrene) crosslinked electrolyte membranes

    Energy Technology Data Exchange (ETDEWEB)

    Soules, A.; Ameduri, B.; Boutevin, B.; David, G. [Institut Charles Gerhardt UMR CNRS 5253 Equipe, Ingenierie et Architectures Macromoleculaires,' ' Ecole Nationale Superieure de Chimie de Montpellier, 8 rue de l' Ecole Normale, 34296 Montpellier, Cedex 05 (France); Perrin, R. [CEA Le Ripault Departement des Materiaux, DMAT/SCMF/LSTP, BP16 - 37260 Monts (France); Gebel, G. [Structure et Proprietes des Architectures Moleculaires UMR 5819 (CEA-CNRS-UJF), INAC, SPrAM, CEA Grenoble, 17 Rue des Martyrs, 38054 Grenoble, Cedex 9 (France)

    2011-10-15

    Potential membranes for polymer electrolyte membrane fuel cell based on crosslinked sulphonated fluorinated polystyrenes (PS) were synthesised in two steps. First, azide-telechelic polystyrene was obtained by iodine transfer polymerisation of styrene in the presence of 1,6-diiodoperfluorohexane followed by azido chain-end functionalisation. Then azide-telechelic polystyrene was efficiently crosslinked with 1,10-diazido-1H,1H,2H,2H,9H,9H,10H,10H-perfluorodecane under UV irradiation. After 45 min only, almost completion of azide crosslinking could be achieved, resulting in crosslinked membranes with insoluble fractions higher than 95%. The sulphonation of the crosslinked membranes afforded ionic exchange capacities (IECs) ranging from 2.2 to 3.2 meq g{sup -1}. The hydration number was shown to be very high (from 30 to 75), depending on both the content of perfluorodecane and of sulphonic acid groups. The morphology of the membranes, assessed by small-angle X-ray scattering, was found to be a lamellar-type structure with two types of ionic domains. For the membrane that exhibited an IEC value of 2.2 meq.g{sup -1}, proton conductivity was in the same range as that of Nafion {sup registered} (120-135 mS.cm{sup -1}), whereas the membrane IEC value of 3.2 meq.g{sup -1} showed a proton conductivity higher than that of Nafion {sup registered} in liquid water from 25 to 80 C, though a high water uptake. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Grafting titanium nitride surfaces with sodium styrene sulfonate thin films

    Science.gov (United States)

    Zorn, Gilad; Migonney, Véronique; Castner, David G.

    2014-01-01

    The importance of titanium nitride lies in its high hardness and its remarkable resistance to wear and corrosion, which has led to its use as a coating for the heads of hip prostheses, dental implants and dental surgery tools. However, the usefulness of titanium nitride coatings for biomedical applications could be significantly enhanced by modifying their surface with a bioactive polymer film. The main focus of the present work was to graft a bioactive poly(sodium styrene sulfonate) (pNaSS) thin film from titanium nitride surfaces via a two-step procedure: first modifying the surface with 3-methacryloxypropyltrimethoxysilane (MPS) and then grafting the pNaSS film from the MPS modified titanium through free radical polymerization. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used after each step to characterize success and completeness of each reaction. The surface region of the titanium nitride prior to MPS functionalization and NaSS grafting contained a mixture of titanium nitride, oxy-nitride, oxide species as well as adventitious surface contaminants. After MPS functionalization, Si was detected by XPS, and characteristic MPS fragments were detected by ToF-SIMS. After NaSS grafting, Na and S were detected by XPS and characteristic NaSS fragments were detected by ToF-SIMS. The XPS determined thicknesses of the MPS and NaSS overlayers were ∼1.5 and ∼1.7 nm, respectively. The pNaSS film density was estimated by the toluidine blue colorimetric assay to be 260 ± 70 ng/cm2. PMID:25280842

  16. Application of Lignin as Antioxidant in Styrene Butadiene Rubber Composite

    Science.gov (United States)

    Liu, Shusheng; Cheng, Xiansu

    2010-11-01

    Lignin isolated from enzymatic hydrolyzed cornstalks (EHL) is a renewable natural polymer, and rubber is one of the most important polymer materials. The application of EHL in rubber industry is of great significance. The influence of EHL and antioxidant RD on the vulcanizing characteristics, thermal oxidative aging stability under free condition, and water extraction resistance of styrene-butadiene rubber (SBR) were investigated. The effect of EHL/antioxidant D composite antioxidant on the thermal oxidative ageing of SBR was also evaluated. Results showed that the protection of SBR from thermal oxidative aging by EHL/antioxidant D composite antioxidant was superior to that of antioxidant D. This is because EHL molecules have hindered phenol group and have excellent auxiliary antioxidant role with antioxidant D. Moreover, the influence of EHL on the vulcanizing characteristics of SBR compounds was better than that of antioxidant RD, and EHL can reduce the cure rate and increase the optimum cure time. It is because that the EHL molecules have hindered phenol group and methoxy group, which can form a special structure to capture free radical and terminate the chain reaction. The retained tensile strength of SBR compounds with EHL was similar to that of the samples with antioxidant RD, while the retained elongation at break of SBR compounds with EHL was higher than that of the samples with antioxidant RD. In addition, the SBR compounds with EHL have a good water extraction resistance property, which was similar to the samples with antioxidant RD. This is because EHL have large molecular weight, good stability and low solubility in water. In conclusion, due to the low price, abundant resources, non-toxic and pollution-free, etc., EHL will have broad application prospect.

  17. AdS solutions through transgression

    Energy Technology Data Exchange (ETDEWEB)

    Donos, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Gauntlett, J.P. [Imperial College, London (United Kingdom). Blackett Lab.]|[Imperial College, London (United Kingdom). The Institute for Mathematical Sciences; Kim, Nakwoo [Kyung Hee Univ., Seoul (Korea). Dept. of Physics and Research Inst. of Basic Science

    2008-07-15

    We present new classes of explicit supersymmetric AdS{sub 3} solutions of type IIB supergravity with non-vanishing five-form flux and AdS{sub 2} solutions of D=11 supergravity with electric four-form flux. The former are dual to two-dimensional SCFTs with (0,2) supersymmetry and the latter to supersymmetric quantum mechanics with two supercharges. We also investigate more general classes of AdS{sub 3} solutions of type IIB supergravity and AdS{sub 2} solutions of D=11 supergravity which in addition have non-vanishing three-form flux and magnetic four-form flux, respectively. The construction of these more general solutions makes essential use of the Chern-Simons or ''transgression'' terms in the Bianchi identity or the equation of motion of the field strengths in the supergravity theories. We construct infinite new classes of explicit examples and for some of the type IIB solutions determine the central charge of the dual SCFTs. The type IIB solutions with non-vanishing three-form flux that we construct include a two-torus, and after two T-dualities and an S-duality, we obtain new AdS3 solutions with only the NS fields being non-trivial. (orig.)

  18. Effects of surfactants on the properties of mortar containing styrene/methacrylate superplasticizer.

    Science.gov (United States)

    Negim, El-Sayed; Kozhamzharova, Latipa; Khatib, Jamal; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    The physical and mechanical properties of mortar containing synthetic cosurfactants as air entraining agent are investigated. The cosurfactants consist of a combination of 2% dodecyl benzene sodium sulfonate (DBSS) and either 1.5% polyvinyl alcohol (PVA) or 1.5% polyoxyethylene glycol monomethyl ether (POE). Also these cosurfactants were used to prepare copolymers latex: styrene/butyl methacrylate (St/BuMA), styrene/methyl methacrylate (St/MMA), and styrene/glycidyl methacrylate (St/GMA), in order to study their effects on the properties of mortar. The properties of mortar examined included flow table, W/C ratio, setting time, water absorption, compressive strength, and combined water. The results indicate that the latex causes improvement in mortar properties compared with cosurfactants. Also polymer latex containing DBSS/POE is more effective than that containing DBSS/PVA.

  19. Final Technical Report - Autothermal Styrene Manufacturing Process with Net Export of Energy

    Energy Technology Data Exchange (ETDEWEB)

    Trubac, Robert , E.; Lin, Feng; Ghosh, Ruma: Greene, Marvin

    2011-11-29

    The overall objectives of the project were to: (a) develop an economically competitive processing technology for styrene monomer (SM) that would reduce process energy requirements by a minimum 25% relative to those of conventional technology while achieving a minimum 10% ROI; and (b) advance the technology towards commercial readiness. This technology is referred to as OMT (Oxymethylation of Toluene). The unique energy savings feature of the OMT technology would be replacement of the conventional benzene and ethylene feedstocks with toluene, methane in natural gas and air or oxygen, the latter of which have much lower specific energy of production values. As an oxidative technology, OMT is a net energy exporter rather than a net energy consumer like the conventional ethylbenzene/styrene (EB/SM) process. OMT plants would ultimately reduce the cost of styrene monomer which in turn will decrease the costs of polystyrene making it perhaps more cost competitive with competing polymers such as polypropylene.

  20. Occupational styrene exposure and acquired dyschromatopsia: A systematic review and meta-analysis.

    Science.gov (United States)

    Choi, Ariel R; Braun, Joseph M; Papandonatos, George D; Greenberg, Paul B

    2017-11-01

    Styrene is a chemical used in the manufacture of plastic-based products worldwide. We systematically reviewed eligible studies of occupational styrene-induced dyschromatopsia, qualitatively synthesizing their findings and estimating the exposure effect through meta-analysis. PubMed, EMBASE, and Web of Science databases were queried for eligible studies. Using a random effects model, we compared measures of dyschromatopsia between exposed and non-exposed workers to calculate the standardized mean difference (Hedges'g). We also assessed between-study heterogeneity and publication bias. Styrene-exposed subjects demonstrated poorer color vision than did the non-exposed (Hedges' g = 0.56; 95%CI: 0.37, 0.76; P dyschromatopsia, suggesting a modest effect size with mild heterogeneity between studies. © 2017 Wiley Periodicals, Inc.

  1. Effects of Surfactants on the Properties of Mortar Containing Styrene/Methacrylate Superplasticizer

    Science.gov (United States)

    Negim, El-Sayed; Kozhamzharova, Latipa; Khatib, Jamal; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    The physical and mechanical properties of mortar containing synthetic cosurfactants as air entraining agent are investigated. The cosurfactants consist of a combination of 2% dodecyl benzene sodium sulfonate (DBSS) and either 1.5% polyvinyl alcohol (PVA) or 1.5% polyoxyethylene glycol monomethyl ether (POE). Also these cosurfactants were used to prepare copolymers latex: styrene/butyl methacrylate (St/BuMA), styrene/methyl methacrylate (St/MMA), and styrene/glycidyl methacrylate (St/GMA), in order to study their effects on the properties of mortar. The properties of mortar examined included flow table, W/C ratio, setting time, water absorption, compressive strength, and combined water. The results indicate that the latex causes improvement in mortar properties compared with cosurfactants. Also polymer latex containing DBSS/POE is more effective than that containing DBSS/PVA. PMID:24955426

  2. Effects of Surfactants on the Properties of Mortar Containing Styrene/Methacrylate Superplasticizer

    Directory of Open Access Journals (Sweden)

    El-Sayed Negim

    2014-01-01

    Full Text Available The physical and mechanical properties of mortar containing synthetic cosurfactants as air entraining agent are investigated. The cosurfactants consist of a combination of 2% dodecyl benzene sodium sulfonate (DBSS and either 1.5% polyvinyl alcohol (PVA or 1.5% polyoxyethylene glycol monomethyl ether (POE. Also these cosurfactants were used to prepare copolymers latex: styrene/butyl methacrylate (St/BuMA, styrene/methyl methacrylate (St/MMA, and styrene/glycidyl methacrylate (St/GMA, in order to study their effects on the properties of mortar. The properties of mortar examined included flow table, W/C ratio, setting time, water absorption, compressive strength, and combined water. The results indicate that the latex causes improvement in mortar properties compared with cosurfactants. Also polymer latex containing DBSS/POE is more effective than that containing DBSS/PVA.

  3. Measurement of styrene oxide in polystyrenes, estimation of migration to foods, and reaction kinetics and products in food simulants.

    Science.gov (United States)

    Philo, M R; Fordham, P J; Damant, A P; Castle, L

    1997-08-01

    The concentration of styrene-7,8-oxide has been measured in nine base resins and 16 samples of polystyrene articles intended for food contact. The epoxide was not detected in the resins (limit of detection 0.5 mg/kg) but was found in 11 of the 16 packaging samples at up to 2.9 mg/kg. Assuming that the propensity of styrene oxide to migrate is the same as styrene monomer, and using existing survey data for styrene monomer in packaging and foods, the migration levels expected for styrene oxide were calculated. Estimates were from 0.002 to 0.15 microgram/kg styrene oxide in foods. The stability of styrene oxide in the four standard EU food simulants was studied at 40, 100, 150 and 175 degrees C, to establish the transformation products to be expected following migration testing. The half-life at 40 degrees C in distilled water, 15% aqueous ethanol, 3% aqueous acetic acid and olive oil was 15, 23, 2000 hr, respectively. The principal product was the diol from hydrolysis of the epoxide group. Ring opening in aqueous ethanol simulant gave the diol and also the glycol monoethyl ether. It is concluded that this instability of styrene oxide will reduce concentrations in foods, from an already low migration level to even lower levels with the formation of hydrolysis products that are less toxic than the parent epoxide.

  4. IMPACT OF AN OZONE GENERATOR AIR CLEANER ON STYRENE CONCENTRATIONS IN AN INDOOR AIR QUALITY RESEARCH CHAMBER

    Science.gov (United States)

    The paper gives results of an investigation of the impact of an ozone generator air cleaner on vapor-phase styrene concentrations in a full-scale indoor air quality test chamber. The time history of the concentrations of styrene and ozone is well predicted by a simulation model u...

  5. Predicting AD conversion

    DEFF Research Database (Denmark)

    Liu, Yawu; Mattila, Jussi; Ruiz, Miguel �ngel Mu�oz

    2013-01-01

    To compare the accuracies of predicting AD conversion by using a decision support system (PredictAD tool) and current research criteria of prodromal AD as identified by combinations of episodic memory impairment of hippocampal type and visual assessment of medial temporal lobe atrophy (MTA) on MRI...

  6. Kinetics and mechanism of styrene epoxidation by chlorite: role of chlorine dioxide.

    Science.gov (United States)

    Leigh, Jessica K; Rajput, Jonathan; Richardson, David E

    2014-07-07

    An investigation of the kinetics and mechanism for epoxidation of styrene and para-substituted styrenes by chlorite at 25 °C in the pH range of 5-6 is described. The proposed mechanism in water and water/acetonitrile includes seven oxidation states of chlorine (-I, 0, I, II, III, IV, and V) to account for the observed kinetics and product distributions. The model provides an unusually detailed quantitative mechanism for the complex reactions that occur in mixtures of chlorine species and organic substrates, particularly when the strong oxidant chlorite is employed. Kinetic control of the reaction is achieved by the addition of chlorine dioxide to the reaction mixture, thereby eliminating a substantial induction period observed when chlorite is used alone. The epoxidation agent is identified as chlorine dioxide, which is continually formed by the reaction of chlorite with hypochlorous acid that results from ClO produced by the epoxidation reaction. The overall stoichiometry is the result of two competing chain reactions in which the reactive intermediate ClO reacts with either chlorine dioxide or chlorite ion to produce hypochlorous acid and chlorate or chloride, respectively. At high chlorite ion concentrations, HOCl is rapidly eliminated by reaction with chlorite, minimizing side reactions between HOCl and Cl2 with the starting material. Epoxide selectivity (>90% under optimal conditions) is accurately predicted by the kinetic model. The model rate constant for direct reaction of styrene with ClO2(aq) to produce epoxide is (1.16 ± 0.07) × 10(-2) M(-1) s(-1) for 60:40 water/acetonitrile with 0.20 M acetate buffer. Rate constants for para substituted styrenes (R = -SO3(-), -OMe, -Me, -Cl, -H, and -NO2) with ClO2 were determined. The results support the radical addition/elimination mechanism originally proposed by Kolar and Lindgren to account for the formation of styrene oxide in the reaction of styrene with chlorine dioxide.

  7. Increased frequency of lymphocyte micronuclei in workers producing reinforced polyester resin with low exposure to styrene

    Energy Technology Data Exchange (ETDEWEB)

    Hoegstedt, B.; Akesson, B.; Axell, K.; Gullberg, B.; Mitelman, F.; Pero, R.W.; Skerfving, S.; Welinder, H.

    1983-06-01

    A new micronucleus method based on the analysis of lymphocytes with preserved cytoplasm revealed an increased frequency of micronuclei in 38 workers employed in a plant producing styrene-modified polyester resin as compared to the frequency in 20 referents (5.9 vs 3.6%). The time-weighted average of the styrene concentration in the workroom air varied between 1 and 36 ppm (mean 13 ppm) during the last year and correlated well to low urinary levels of mandelic acid, which ranged from 9 to 316 mg/g of creatinine (mean 65 mg/g of creatinine).

  8. Impact behaviour of acrylonitrile-butadiene-styrene after temperature and humidity load

    Directory of Open Access Journals (Sweden)

    Hylova Lenka

    2017-01-01

    Full Text Available This study deals with acrylonitrile-butadiene-styrene (ABS which was subjected the drop-weight test before and after temperature and humidity load. ABS is an engineering plastic and also an important engineering terpolymer, which has butadiene part uniformly distributed through the acrylonitrile-styrene matrix and is commonly used in production of automotive interior components. The injection moulded ABS samples were subjected the penetration test at fall height 100 J before and after temperature and humidity load and the results were subsequently evaluated and discussed. It was found out that ABS after temperature and humidity load has lower impact resistance.

  9. Kinetic study of the selective hydrogenation of styrene over a Pd egg-shell composite catalyst

    OpenAIRE

    Betti,Carolina; Badano,Juan; Lederhos,Cecilia; Maccarrone, María; Carrara, Nicolás; Coloma, Fernando; Quiroga, Mónica; Vera, Carlos

    2016-01-01

    This is a study on the kinetics of the liquid-phase hydrogenation of styrene to ethylbenzene over a catalyst of palladium supported on an inorganic–organic composite. This support has a better mechanical resistance than other commercial supports, e.g. alumina, and yields catalysts with egg-shell structure and a very thin active Pd layer. Catalytic tests were carried out in a batch reactor by varying temperature, total pressure and styrene initial concentration between 353–393 K, 10–30 bar, an...

  10. Adding more value to added-value

    DEFF Research Database (Denmark)

    Marian, Livia

    Recent studies reveal that consumers respond favourably to “organic plus” products with additional ethical attributes. The aim of the current study is to explore whether consumers would notice and value further improvements in the animal welfare standards than those imposed by the organic...... it is probably valued less than expected. The added attributes need to be thoroughly considered when developing and marketing “organic plus” products, as their effect on other product characteristics (e.g. high prices) can detract from their added value....

  11. Synthesis of High cis-Polybutadiene in Styrene Solution with Neodymium-Based Catalysts: Towards the Preparation of HIPS and ABS via In Situ Bulk Polymerization

    Directory of Open Access Journals (Sweden)

    Ramón Díaz de León

    2016-01-01

    Full Text Available In a first step, 1,3-butadiene was selectively polymerized at 60°C in styrene as solvent using NdV3/DIBAH/EASC as the catalyst system. The catalyst system activation process, the addition order of monomers and catalyst components, and the molar ratios [Al]/[Nd] and [Cl]/[Nd] were studied. The catalyst system allowed the selective 1,3-butadiene polymerization, reaching conversions between 57.5 and 88.1% with low polystyrene contents in the order of 6.3 to 15.4%. Molecular weights ranging from 39,000 to 150,000 g/mol were obtained, while cis-1,4 content was found in the interval of 94.4 to 96.4%. On the other hand, the glass transition temperatures of synthesized materials were established in the range of −101.9 to −107.4°C, explained by the presence of polystyrene segments in the polybutadiene chains; in the same sense, the polybutadienes did not show the typical melting endotherm of high cis-polybutadienes. In a second step, the resulting styrene/high cis-1,4 polybutadiene solutions were used to synthesize ABS (adding a fraction of acrylonitrile monomer and HIPS via in situ bulk polymerizations and the results were discussed in terms of morphological development, molecular parameters, dynamical mechanical behavior, and mechanical properties.

  12. The political attack ad

    Directory of Open Access Journals (Sweden)

    Palma Peña-Jiménez, Ph.D.

    2011-01-01

    Full Text Available During election campaigns the political spot has a clear objective: to win votes. This message is communicated to the electorate through television and Internet, and usually presents a negative approach, which includes a direct critical message against the opponent, rather than an exposition of proposals. This article is focused on the analysis of the campaign attack video ad purposely created to encourage the disapproval of the political opponent among voters. These ads focus on discrediting the opponent, many times, through the transmission of ad hominem messages, instead of disseminating the potential of the political party and the virtues and manifesto of its candidate. The article reviews the development of the attack ad since its first appearance, which in Spain dates back to 1996, when the famous Doberman ad was broadcast, and examines the most memorable campaign attack ads.

  13. Twistor methods for AdS$_5$

    CERN Document Server

    Adamo, Tim; Williams, Jack

    2016-01-01

    We consider the application of twistor theory to five-dimensional anti-de Sitter space. The twistor space of AdS$_5$ is the same as the ambitwistor space of the four-dimensional conformal boundary; the geometry of this correspondence is reviewed for both the bulk and boundary. A Penrose transform allows us to describe free bulk fields, with or without mass, in terms of data on twistor space. Explicit representatives for the bulk-to-boundary propagators of scalars and spinors are constructed, along with twistor action functionals for the free theories. Evaluating these twistor actions on bulk-to-boundary propagators is shown to produce the correct two-point functions.

  14. Swelling of organoclays in styrene. Effect on flammability in polystyrene nanocomposites

    Directory of Open Access Journals (Sweden)

    2010-08-01

    Full Text Available In this work the effect of the compatibility between organoclays and styrene on the flammability of polystyrene/clay nanocomposites obtained through in situ incorporation was investigated. The reactions were carried out by bulk polymerization. The compatibility between organoclays and styrene was inferred from swelling of the organoclay in styrene. The nanocomposites were characterized by X-ray diffraction and Transmission Electron Microscopy. The heat release rate was obtained by Cone Calorimeter and the nanocomposites were tested by UL94 horizontal burn test. Results showed that intercalated and partially exfoliated polystyrene/clay nanocomposites were obtained depending on the swelling behavior of the organoclay in styrene. The nanocomposites submitted to UL94 burning test presented a burning rate faster than the virgin polystyrene (PS, however an increase of the decomposition temperature and an accentuated decrease on the peak of heat release of the nanocomposites were also observed compared to virgin PS. These results indicate that PS/clay nanocomposites, either intercalated or partially exfoliated, reduced the flammability approximately by the same extent, although reduced the ignition resistance of the PS.

  15. 0177 Exposure to styrene and the risk of cancer

    DEFF Research Database (Denmark)

    Christensen, Mette Skovgaard; Hansen, J; Ramlau-Hansen, Cecilia

    2014-01-01

    following occupational styrene exposure. METHOD: The cohort consists of 74 902 workers (84% men) in the Danish reinforced plastics industry, originating from 481 companies ever producing reinforced plastics in Denmark 1964-2009. We identified all workers in the National Supplementary Pension Fund Registry...

  16. Cyclodimerization of Stilbenes and Styrenes Catalyzed by Heteropolyacid Supported on Silica

    Directory of Open Access Journals (Sweden)

    B. Lantaño

    2000-03-01

    Full Text Available Several stilbenes and styrenes have been treated with heteropolyacid] (HPA supported over silice. The compounds obtained were characterized by 1H and 13C- NMR and the yields were compared with those obtained using H2SO4 (c and ethyl poliphosphate] (PPE.

  17. ASSESSMENT OF STYRENE EMISSION CONTROLS FOR FRP/C AND BOAT BUILDING INDUSTRIES

    Science.gov (United States)

    The report gives results of an evaluation of several conventional and novel emission control technologies that have been used or could be used to treat styrene emissions from open molding processes in fiberglass-reinforced plastics/composites (FRP/C) and fiberglass boat building ...

  18. Development of bioconjugated dye-doped poly(styrene-co-maleimide) nanoparticles as a new bioprobe

    CSIR Research Space (South Africa)

    Swanepoel, A

    2015-02-01

    Full Text Available -1 Journal of Materials Chemistry B Development of bioconjugated dye-doped poly(styrene-co- maleimide) nanoparticles as a new bioprobe A. Swanepoel, I. du Preez, T. Mahlangu, A. Chetty and B. Klumperman Abstract Fluorescent dye-doped poly...

  19. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Science.gov (United States)

    2010-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL..., ethylene oxide adduct. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene oxide...

  20. Expanding Upon Styrene Biosynthesis to Engineer a Novel Route to 2-Phenylethanol.

    Science.gov (United States)

    Machas, Michael S; McKenna, Rebekah; Nielsen, David R

    2017-10-01

    2-Phenylethanol (2PE) is a key molecule used in the fragrance and food industries, as well as a potential biofuel. In contrast to its extraction from plant biomass and/or more common chemical synthesis, microbial 2PE production has been demonstrated via both native and heterologous expression of the yeast Ehrlich pathway. Here, a novel alternative to this established pathway is systematically engineered in Escherichia coli and evaluated as a more robust and efficient route. This novel pathway is constructed via the modular extension of a previously engineered styrene biosynthesis pathway, proceeding from endogenous l-phenylalanine in five steps and involving four heterologous enzymes. This "styrene-derived" pathway boasts nearly a 10-fold greater thermodynamic driving force than the Ehrlich pathway, and enables reduced accumulation of acetate byproduct. When directly compared using a host strain engineered for l-phenylalanine over-production, preservation of phosphoenolpyruvate, and reduced formation of byproduct 2-phenylacetic acid, final 2PE titers via the styrene-derived and Ehrlich pathways reached 1817 and 1164 mg L-1 , respectively, at yields of 60.6 and 38.8 mg g-1 . Following optimization of induction timing and initial glucose loading, 2PE titers by the styrene-derived pathway approached 2 g L-1 - nearly a two-fold twofold increase over prior reports for 2PE production by E. coli employing the Ehrlich pathway. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Breath and blood levels of benzene, toluene, cumene and styrene in non-occupational exposure.

    Science.gov (United States)

    Brugnone, F; Perbellini, L; Faccini, G B; Pasini, F; Maranelli, G; Romeo, L; Gobbi, M; Zedde, A

    1989-01-01

    Benzene, toluene, cumene and styrene were measured in the breath and blood of two groups of individuals. The first group included individuals belonging to a hospital staff, the second group included chemical workers who were not exposed to the abovementioned chemicals. The chemical workers were examined in plant infirmaries on the morning before the start of the workshift, and the hospital staff in the hospital infirmaries. One environmental air sample was taken in the infirmaries for each individual at the moment of the biological samplings. The environmental concentrations of benzene and styrene were significantly higher in the infirmaries of the chemical plant than in the infirmaries of the hospital. On the other hand, the environmental concentrations of toluene and cumene were not significantly different in the plant infirmaries and in the hospital infirmaries. In the hospital staff the alveolar concentrations of benzene, toluene and styrene were significantly lower than those in the chemical workers. In the hospital staff the blood concentrations of benzene, toluene and styrene were not significantly different from those in the chemical workers. Only the blood cumene concentration was significantly higher in the chemical workers. In hospital staff, smokers showed alveolar and blood concentrations of benzene and toluene that were significantly higher than those measured in the non smoker hospital staff. With reference to chemical workers, only alveolar benzene concentration was significantly higher in smokers than in non smokers.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Embryotoxic and teratogenic effects of styrene derivatives on sea urchin development.

    Science.gov (United States)

    Pagano, G; Esposito, A; Giordano, G G; Hagström, B E

    1978-01-01

    The effects of styrene and some of its derivatives on the fertilization and differentiation of sea urchins was investigated. When one of the gametes was pretreated for a few minutes, it was ascertained that the test substances act on the haploid nucleus, producing specific changes in the differentiation of the embryo. By this test system directly acting, weak mutagens may be detected.

  3. Global styrene oligomers monitoring as new chemical contamination from polystyrene plastic marine pollution.

    Science.gov (United States)

    Kwon, Bum Gun; Koizumi, Koshiro; Chung, Seon-Yong; Kodera, Yoichi; Kim, Jong-Oh; Saido, Katsuhiko

    2015-12-30

    Polystyrene (PS) plastic marine pollution is an environmental concern. However, a reliable and objective assessment of the scope of this problem, which can lead to persistent organic contaminants, has yet to be performed. Here, we show that anthropogenic styrene oligomers (SOs), a possible indicator of PS pollution in the ocean, are found globally at concentrations that are higher than those expected based on the stability of PS. SOs appear to persist to varying degrees in the seawater and sand samples collected from beaches around the world. The most persistent forms are styrene monomer, styrene dimer, and styrene trimer. Sand samples from beaches, which are commonly recreation sites, are particularly polluted with these high SOs concentrations. This finding is of interest from both scientific and public perspectives because SOs may pose potential long-term risks to the environment in combination with other endocrine disrupting chemicals. From SOs monitoring results, this study proposes a flow diagram for SOs leaching from PS cycle. Using this flow diagram, we conclude that SOs are global contaminants in sandy beaches around the world due to their broad spatial distribution. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Prognosis and determination of the threshold of chronic effect of carbon disulfide and styrene

    Energy Technology Data Exchange (ETDEWEB)

    Popov, T.; Zaprianov, Z.; Benchev, I.; Spasovski, M.

    1982-01-01

    Two series of studies were carried out: I--in workers exposed to four different mean annual CS/sub 2/ concentrations(6 mg/m3m3; 12 mg/m3; 51 mg/m3 and 247 mg/m3 and II series) in workers exposed to three styrene concentrations-(-I mg/m3; 40 mg/m3 and 400 mg/m3). The results obtained in series I show the role of the primary toxic effect (inhibition of oxidases with mixed function) and of the adaptation reactions to it with a view to accurate specifying the threshold of chronic CS/sub 2/ effect. The mathematical expression of the correlation between styrene concentration in air and blood, of phenyl-glyoxylic and mandelic acid in the urine of the exposed subjects enables the prognosis that the threshold of the noxious styrene effect is within the range of 150 mg/m3 to 250 mg/m3. A reduction on CS/sub 2/ MAC is proposed-(-from 10 mg/m3 to I mg/m3) and the correction of styrene MAC-(-from 5 mg/m3 to 30-50 mg/m3).

  5. Ionomeric membranes based on partially sulfonated poly(styrene) : synthesis, proton conduction and methanol permeation

    NARCIS (Netherlands)

    Picchioni, F.; Tricoli, V.; Carretta, N.

    2000-01-01

    Homogeneuosly sulfonated poly(styrene) (SPS) was prepared with various concentration of sulfonic acid groups in the base polymer. Membranes cast from these materials were investigated in relation to proton conductivity and methanol permeability in the temperature range from 20°C to 60°C. It was

  6. Development of Styrene-Grafted Polyurethane by Radiation-Based Techniques

    Directory of Open Access Journals (Sweden)

    Jin-Oh Jeong

    2016-06-01

    Full Text Available Polyurethane (PU is the fifth most common polymer in the general consumer market, following Polypropylene (PP, Polyethylene (PE, Polyvinyl chloride (PVC, and Polystyrene (PS, and the most common polymer for thermosetting resins. In particular, polyurethane has excellent hardness and heat resistance, is a widely used material for electronic products and automotive parts, and can be used to create products of various physical properties, including rigid and flexible foams, films, and fibers. However, the use of polar polymer polyurethane as an impact modifier of non-polar polymers is limited due to poor combustion resistance and impact resistance. In this study, we used gamma irradiation at 25 and 50 kGy to introduce the styrene of hydrophobic monomer on the polyurethane as an impact modifier of the non-polar polymer. To verify grafted styrene, we confirmed the phenyl group of styrene at 690 cm−1 by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR and at 6.4–6.8 ppm by 1H-Nuclear Magnetic Resonance (1H-NMR. Scanning Electron Microscope (SEM, X-ray Photoelectron Spectroscopy (XPS, Thermogravimetric Analysis (TGA and contact angle analysis were also used to confirm styrene introduction. This study has confirmed the possibility of applying high-functional composite through radiation-based techniques.

  7. Particle reinforced composites from acrylamide modified blend of styrene-butadiene and natural rubber

    Science.gov (United States)

    Blends of styrene-butadiene rubber and natural rubber that provide balanced properties were modified with acrylamide and reinforced with soy protein particles. The rubber composites show improved mechanical properties. Both modified rubber and composites showed a faster curing rate. The crosslinking...

  8. Synthesis of crosslinked poly(styrene-co-divinylbenzene-co ...

    Indian Academy of Sciences (India)

    Administrator

    molecular weight distribution have unique properties which make them interesting and find applications in numerous ... late (SPM, Poly Sciences), sodium dodecyl sulfate (SDS,. Merck), sodium bicarbonate (Sisco) and ... of double distilled water and 0⋅1 g of sodium bicarbonate was added. A stirring rate of 360 rpm and a ...

  9. Cationic surfactants/copoly(styrene oxide-ethylene oxide) systems: A physico-chemical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Taboada, Pablo [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela (Spain)], E-mail: fmpablo@usc.es; Castro, Emilio [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela (Spain); Barbosa, Silvia [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela (Spain); Mosquera, Victor [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela (Spain)

    2005-07-18

    The interactions between the diblock copolymer S{sub 15}E{sub 63} and the surfactants dodecyltrimethylammonium (DoTAB) and hexadecyltrimethylammoniun (CTAB) bromides have been investigated by dynamic light scattering, transmission electron microscopy and isothermal titration calorimetry. The surfactants with the same headgroup differentiate in their chain length. At 20 deg C, the block copolymer is associated into micelles with a hydrodynamic radius of 11.3 nm, which is composed of a hydrophobic styrene oxide (S) core and a water-swollen oxypolyethylene (PEO) corona. The different copolymer/surfactant systems have been studied at a constant copolymer concentration of 2.5 g dm{sup -3} and in a vast range of surfactant concentration, from 5.0 x 10{sup -6} up to 0.1 M. When DoTAB is added to the block copolymer solution, no important variations are observed in the apparent hydrodynamic radius up to a surfactant concentration of {approx}10{sup -2} M, for which this magnitude starts decreasing abruptly as a consequence of disruption of the copolymer micelles due to surfactant binding. This phenomenon is also observed for CTAB but at much lower concentrations ({approx}10{sup -5} M). This decrease is associated to repulsive electrostatic interactions between surfactant headgroups in the micelle. Complete disruption of the mixed aggregates occurs neither for DoTAB nor CTAB in the measured concentration range. Transmission electron microscopy has confirmed this behaviour. Titration calorimetric data of micellised DoTAB present a plateau region indicating no interaction between the copolymer and the surfactant at low surfactant concentrations, followed by an exothermic decrease as a consequence of starting copolymer micelle disruption. For CTAB, an endothermic maximum points out the existence of interactions between copolymer micelles and this surfactant. This maximum is followed by a steep decrease which reflects the disruption of the mixed surfactant/copolymer micelles up

  10. Plane-interface-induced lignin-based nanosheets and its reinforcing effect on styrene-butadiene rubber

    Directory of Open Access Journals (Sweden)

    C. Jiang

    2014-09-01

    Full Text Available Lignin was viewed as a spherical microgel in aqueous alkali. While spread out in a monolayer or adsorbed on a surface, lignin was made up of flexible, disk-like molecules with approximately the same thickness of 2 nm. According to this principle, we employed the lamina of montmorillonite (MMT as a plane template to anchor cationic lignin (CL on its two sides, resulting in the formation of CL-MMT hybrid materials (CLM. The isotherm adsorption behavior and structure characteristics of CLM were studied. The results showed that CLM was individually dispersed nanosheets with a thickness of about 5 nm when the mass ratio of CL to MMT is more than 2:1 and prepared at acidic or neutral pH. Compared to the cocoagulation of lignin and styrene-butadiene rubber (SBR, CLM obviously accelerated the coagulation rate, due to the reduction of surface activity of CL restricted by MMT. The nanoscale dispersion of CLM in SBR matrix significantly improved the tensile strength of CLM/SBR nanocomposites to 14.1 MPa by adding only 10 phr CLM and cardanol glycidyl ether (CGE as compatibilizer. Dynamic mechanical analysis (DMA showed that the glass transition temperature of SBR/CLM nanocomposites decreased with increasing CLM loading. Correspondingly, a special interfacial structure was proposed.

  11. Use of an acrylonitrile-butadiene-styrene (ABS) plastic ring as a matrix in the recovery of bite mark evidence.

    Science.gov (United States)

    Sweet, D J; Bastien, R B

    1991-09-01

    Valuable forensic information can be obtained from analysis of human bite mark injuries after careful retrieval of such evidence from living or deceased victims. It is difficult, however, to maintain the anatomical configuration of the skin, especially where body contours complicate the recovery process. Transillumination of the injury pattern in the skin after removal and preservation of the tissue from a deceased victim can provide significant information in the investigation process. A dimensionally stable matrix is required to support the skin's anatomical configuration during and after its removal. The authors have developed a unique and convenient method of heating and contouring a ring of acrylonitrile-butadiene-styrene (ABS) plastic using table salt over a heat source. When this ring is applied to the deceased victim's skin, and a backing material is added for support, removal of the skin and the bite mark can be accomplished more predictably while maintaining the anatomical contour. It is important to record bite marks accurately as soon after discovery as possible; the authors believe that this technique will significantly aid recovery of such evidence either at the crime scene or in the laboratory. A method of inscribing appropriate anatomical markers and case numbers on the rings is also described.

  12. Heterogeneous catalytic oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Badstube, T.; Papp, H. [Leipzig Univ. (Germany). Inst. fuer Technische Chemie; Kustrowski, P.; Dziembaj, R. [Jagiellonian Univ., Crakow (Poland). Faculty of Chemistry

    1998-12-31

    Alkaline promoted active carbon supported iron catalysts are very active in the oxidative dehydrogenation of ethylbenzene to styrene in the presence of carbon dioxide. The best results were obtained at 550 C for a Li-promoted catalyst with a conversion of ethylbenzene of 75% and a selectivity towards styrene of nearly 95%. These results are better than those obtained with industrial catalysts which perform the dehydrogenation process with an excess of water. The main product of the dehydrogenation reaction with CO{sub 2} was styrene, but the following by-products were detected - benzene and toluene. The selectivity towards toluene was always higher than towards benzene. We observed also the formation of carbon monoxide and water, which were produced with a constant molar ratio of about 0.8. The weight of the catalysts increased up to 20% during the reaction due to deposition of carbon. Using a too large excess of CO{sub 2} (CO{sub 2}/EB>10) was harmful for the styrene yield. The most favorable molar ratio of CO{sub 2} to EB was 10:1. No correlation between the molar ratios of reactants and the amount of deposited coke on the surface of catalysts was observed. The highest catalytic activity showed iron loaded D-90 catalysts which were promoted with alkali metals in a molar ratio of 1:10. Iron, nickel and cobalt loaded carbonized PPAN, PC, inorganic supports like Al{sub 2}O{sub 3}, SiO{sub 2}/ZrO{sub 2} or TiO{sub 2} respectively and commercial iron catalysts applied for styrene production did not show comparable catalytic activity in similar conditions. (orig.)

  13. Simulation of the styrene production process via catalytic dehydrogenation of ethylbenzene using CHEMCAD® process simulator

    Directory of Open Access Journals (Sweden)

    Amaury Pérez Sánchez

    2017-07-01

    Full Text Available Background: Process simulation has been extensively used in recent years to design, evaluate or optimize processes, systems and specific operations of the chemical industry and its related disciplines. Currently, CHEMCAD® constitute one of the most used process simulators because of the great number of chemical and petrochemical processes that can be simulated. Method: The simulation of the production process of styrene via catalytic dehydrogenation of ethyl-benzene is carried out by using the process simulator CHEMCAD® version 5.2.0, in order to determine the composition and mass flow-rate of each process involved in the production, as well as the main operating parameters of the equipment used. Two sensitivity studies were carried out: firstly, the influence of the temperature and pressure values applied at the LLV Separator on the amounts of ethyl-benzene and styrene to be obtained by the intermediate and top currents of this equipment; secondly, the influence of the operating pressure of the Distillation Column No. 1 (benzene-toluene column on the quantity of ethyl-benzene and styrene obtained at the bottom stream. The simulating software MATLAB® version 7.8.0 was used to process the results obtained. Results: Around 9234.436 kg/h of styrene is obtained in the last distillation column with 99.6% purity. Additionally, it was found that the water is the main impurity found on this stream, which represents 0.35% of the weight. Conclusions: The LLV Separator must operate at a low temperature (5 – 10 ºC and at a relatively high pressure (10 bar, whereas the Distillation Column No. 1 must work at a pressure near atmospheric (1.0 bar, or preferably under vacuum conditions in order to obtain the highest yields of styrene and ethyl-benzene.

  14. Skil problemerne ad

    DEFF Research Database (Denmark)

    Kaspersen, Peter

    2007-01-01

    På grundlag af evalueringer og forskning i gymnasiereformen 2005 foreslås det at skille problemerne ad i forskellige niveauer. Herved kan der arbejdes med niveaudelte løsninger.......På grundlag af evalueringer og forskning i gymnasiereformen 2005 foreslås det at skille problemerne ad i forskellige niveauer. Herved kan der arbejdes med niveaudelte løsninger....

  15. Effect of porosity and environment on the mechanical behavior of acrylic bone cement modified with acrylonitrile-butadiene-styrene particles: part II. Fatigue crack propagation.

    Science.gov (United States)

    Vila, M M; Ginebra, M P; Gil, F J; Planell, J A

    1999-01-01

    The aim of this study was to investigate the effect of adding an elastomeric second phase, acrylonitrile-butadiene-styrene, on the fatigue crack propagation behavior of poly(methyl methacrylate) bone cement. Moreover, the influence of porosity and environmental conditions was studied. When comparing the plain cement to the modified cement, a decrease in the crack propagation rate was observed at between 1 and 2 orders of magnitude. The storage in a physiological environment (saline solution at 37 degrees C) also caused a decrease in the crack propagation rate of about 2 orders of magnitude for the plain and modified cement prepared in air or under a vacuum. Porosity did not have any noticeable effect on the fatigue crack propagation behavior of the cement.

  16. Effect of porosity and environment on the mechanical behavior of acrylic bone cement modified with acrylonitrile-butadiene-styrene particles: I. Fracture toughness.

    Science.gov (United States)

    Vila, M M; Ginebra, M P; Gil, F J; Planell, J A

    1999-01-01

    The elastomeric copolymer acrylonitrile-butadiene-styrene (ABS) was added to a conventional acrylic bone cement matrix. The results obtained show that although strength and stiffness decreased with an increasing second phase volume fraction, ductility and toughness both increased. The crack propagation became stable for specimens containing over a 5% volume fraction of the second phase. The fracture toughness increased up to 60% when the amount of ABS reached 20% (v/v). For larger amounts linear elastic fracture mechanics techniques could not be used properly. The effects of porosity and environmental conditions on the mechanical behavior were also studied. The mechanisms that control the fracture process were investigated by means of scanning electron microscopy.

  17. Development of value added tea bags and capsules of Artemisia ...

    African Journals Online (AJOL)

    Propagation to budding/harvesting took 4 months and fresh leaves were processed to dark green dried leaves which was developed to value added products of tea bags and powdered capsules following the Noble Icon NAFDAC approved procedures and equipment; and Now Food University in USA procedures and ...

  18. Probing crunching AdS cosmologies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. Prem; Vaganov, Vladislav [Department of Physics, Swansea University,Singleton Park, Swansea SA2 8PP (United Kingdom)

    2016-02-03

    Holographic gravity duals of deformations of CFTs formulated on de Sitter spacetime contain FRW geometries behind a horizon, with cosmological big crunch singularities. Using a specific analytically tractable solution within a particular single scalar truncation of N=8 supergravity on AdS{sub 4}, we first probe such crunching cosmologies with spacelike radial geodesics that compute spatially antipodal correlators of large dimension boundary operators. At late times, the geodesics lie on the FRW slice of maximal expansion behind the horizon. The late time two-point functions factorise, and when transformed to the Einstein static universe, they exhibit a temporal non-analyticity determined by the maximal value of the scale factor ã{sub max}. Radial geodesics connecting antipodal points necessarily have de Sitter energy E≲ã{sub max}, while geodesics with E>ã{sub max} terminate at the crunch, the two categories of geodesics being separated by the maximal expansion slice. The spacelike crunch singularity is curved “outward” in the Penrose diagram for the deformed AdS backgrounds, and thus geodesic limits of the antipodal correlators do not directly probe the crunch. Beyond the geodesic limit, we point out that the scalar wave equation, analytically continued into the FRW patch, has a potential which is singular at the crunch along with complex WKB turning points in the vicinity of the FRW crunch. We then argue that the frequency space Green’s function has a branch point determined by ã{sub max} which corresponds to the lowest quasinormal frequency.

  19. The improvement of corrosion resistance of fluoropolymer coatings by SiO{sub 2}/poly(styrene-co-butyl acrylate) nanocomposite particles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L. [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China); Song, R.G., E-mail: songrg@hotmail.com [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China); Li, X.W.; Guo, Y.Q.; Wang, C.; Jiang, Y. [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China)

    2015-10-30

    Highlights: • We first proposed the feasibility of organic-inorganic hybrid particles can be used to reduce free space of the fluoropolymer coatings. • By grafting poly(styrene-co-butyl acrylate), nano-silica particles can be better dispersed in the fluoropolymer coatings system. • The coating-substrates bound strength could be obviously seen in the FESEM cross-section images. • The effects of the corrosion resistance of fluoropolymer-coated steel were investigated by potentiodynamic polarization and EIS. • Using models to analysis the anticorrosion mechanism of nanocomposite coatings. - Abstract: The effects of nano-silica particles on the anticorrosion properties of fluoropolymer coatings on mild steel have been investigated in this paper. In order to enhance the dispersibility of nano-silica in fluoropolymer coatings, we treated the surface of nano-silica with poly(styrene-co-butyl acrylate) (P(St-BA)). The surface grafting of P(St-BA) on the nanoparticles were detected using Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric analyzer (TGA), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The surface of nanocomposite coatings and the coating-substrates bond texture were detected by FE-SEM. We also used energy-dispersive X-ray spectroscopy (EDS) to analyze whether the nanocomposite particles were added into the fluoropolymer coatings. In addition, the influences of various nanoparticles on the corrosion resistance of fluoropolymer-coated steel were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results shown that nanocomposite particles can be dispersed better in fluoropolymer coatings, and the electrochemical results clearly shown the improvement of the protective properties of the nanocomposite coatings when 4 wt.% SiO{sub 2}/P(St-BA) was added to the fluoropolymer coatings.

  20. Microbiota analysis to reveal temperature abuse of fresh pork

    DEFF Research Database (Denmark)

    Buschhardt, Tasja; Bahl, Martin Iain; Hansen, Tina Beck

    Violations of temperature regulations in the meat chain may affect meat safety. Methods are lacking to estimate whether meat has been subjected to temperature abuse. Exposure to too high temperatures may lead to systematic changes in the diverse bacterial communities of fresh meat. We investigated...... whether temperature induced changes in the community composition on fresh meat surfaces can reflect the temperature-history (combination of time and temperature). Sterile pieces of pork were inoculated with a carcass swab homogenate, to which Salmonella was added. Changes in the meat microbiota were...... was dominated by Pseudomonas only. We also showed that the initial community affects subsequent changes during storage. The results suggest that principal coordinate analysis of beta diversity could be a useful tool to reveal temperature abused meat. Sequence data and culturing data revealed a strong positive...

  1. Reduction of radiation injury of fresh agricultural products by saccharide

    Energy Technology Data Exchange (ETDEWEB)

    Todoroki, Setsuko; Hayashi, Toru [National Food Research Inst., Tsukuba, Ibaraki (Japan)

    1999-02-01

    Radiation exposure has been paid attention as an alternative technique of methylbromide to protect agricultural products against insects. However, it has been pointed out that radiation at a dose lower than 300-400 Gy necessary for insecticidal effects might produce damages in fresh agricultural products. To reduce such radiation damages, radiation sensitivities of various fresh products were determined to clarify whether sugar treatment is effective for reduction of damages. Further, the timing of the treatment and its influence on the metabolism of agricultural product were investigated. When sucrose was added to a cut flower of chrysanthemum via water before and during irradiation, the withering time of its leaves and flowers was earlier than that of the untreated product, whereas continuous administration of sucrose after radiation exposure caused to lengthen the flower`s life and delay the leave`s yellowing. Thus, it was indicated that continuous sugar supply after irradiation was effective for prevention of radiation damages. (M.N.)

  2. Mobile ad hoc networking

    CERN Document Server

    John Wiley & Sons

    2004-01-01

    "Assimilating the most up-to-date information on research and development activities in this rapidly growing area, Mobile Ad Hoc Networking covers physical, data link, network, and transport layers, as well as application, security, simulation, and power management issues in sensor, local area, personal, and mobile ad hoc networks. Each of the book's sixteen chapters has been written by a top expert and discusses in-depth the most important topics in the field. Mobile Ad Hoc Networking is an excellent reference and guide for professionals seeking an in-depth examination of topics that also provides a comprehensive overview of the current state-of-the-art."--Jacket.

  3. Antiproton-Decelerator (AD)

    CERN Multimedia

    Laurent Guiraud

    1998-01-01

    When the Low-Energy Antiproton Ring (LEAR) was stopped in 1996, because of its costly operation, a cheaper way of continuing low-energy antiproton physics was sought. The Antiproton-Collector (AC), added in 1987 to the Antiproton Accumulator (AA) to provide a tenfold intensity increase, was converted into the Antiproton-Decelerator (AD). Antiprotons from the target at 3.5 GeV/c are decelerated to 100 MeV/c, and fast-ejected to the experiments. Major changes were necessary. Above all, the conversion from a constant-field machine to one with a magnetic cycle, modulating the field by an impressive factor 35. New systems for stochastic and electron cooling had to be added. Beam diagnostics at an intensity of only 2E7 antiprotons was a challenge. In 2000, the AD began delivery of antiprotons to the experiments.

  4. Desenvolvimento de massa alimentícia fresca funcional com a adição de isolado protéico de soja e polidextrose utilizando páprica como corante Development of functional fresh food adding soy protein isolate and polidextrose using paprika as coloring agent

    Directory of Open Access Journals (Sweden)

    Luz Maria Paucar-Menacho

    2008-12-01

    áprica foram de 3,5, 8,0 e 1,5%, respectivamente.The trend of the current consumer is to use foods that are easy to prepare and that besides having nutritional quality provide health benefits. In this work, fresh food with functional characteristics was developed incorporating Soy Protein Isolate (SPI and polidextrose using paprika as the coloring agent. The consumption of IPS could contribute to decrease cholesterol levels while polidextrose, acting as a fiber, could promote the reduction of risk of colon cancer. The optimization of the formulation was carried out using a 23 complete factorial design considering independent variables the following contents: i SPI; ii polidextrose; and iii paprika. The effects of these variables on the quality of the food were evaluated through physical-chemical characteristics (color and cooking test, instrumental texture, and sensory analysis. Regarding the physical parameters, instrumental color of the raw pasta was affected only by the addition of paprika. The parameters cooking time (2.5 minutes, increase in mass (1.40 to 1.64%, and loss of solids (3.80 to 5.56% were not influenced by the ingredients used. Elasticity (instrumental texture parameter was reduced with the increase of polidextrose. Regarding sensory analysis of the raw food, an increase in the addition of SPI and a reduction in the addition of polidextrose positively affected global acceptance and purchase intention. An increases in SPI and paprika increased color acceptance. Regarding sensory analysis of the cooked food, SPI had a positive effect on texture while polidextrose and paprika negatively affected this parameter. Nevertheless, the ingredients used did not influence purchase intention of the cooked food. The ideal percentages of polidextrose, soy protein isolate, and paprika were 3.5, 8.0, and 1.5%, respectively.

  5. Volume shrinkage and rheological studies of epoxidised and unepoxidised poly(styrene-block-butadiene-block-styrene) triblock copolymer modified epoxy resin-diamino diphenyl methane nanostructured blend systems.

    Science.gov (United States)

    George, Sajeev Martin; Puglia, Debora; Kenny, Josè M; Parameswaranpillai, Jyotishkumar; Vijayan P, Poornima; Pionteck, Jűrgen; Thomas, Sabu

    2015-05-21

    Styrene-block-butadiene-block-styrene (SBS) copolymers epoxidised at different epoxidation degrees were used as modifiers for diglycidyl ether of the bisphenol A-diamino diphenyl methane (DGEBA-DDM) system. Epoxy systems containing modified epoxidised styrene-block-butadiene-block-styrene (eSBS) triblock copolymer with compositions ranging from 0 to 30 wt% were prepared and the curing reaction was monitored in situ using rheometry and pressure-volume-temperature (PVT) analysis. By controlling the mole percent of epoxidation, we could generate vesicles, worm-like micelles and core-shell nanodomains. At the highest mole percent of epoxidation, the fraction of the epoxy miscible component in the triblock copolymer (epoxidised polybutadiene (PB)) was maximum. This gave rise to core-shell nanodomains having a size of 10-15 nm, in which the incompatible polystyrene (PS) becomes the core, the unepoxidised PB becomes the shell and the epoxidised PB interpenetrates with the epoxy phase. On the other hand, the low level of epoxidation gave rise to bigger domains having a size of ∼1 μm and the intermediate epoxidation level resulted in a worm-like structure. This investigation specifically focused on the importance of cure rheology on nanostructure formation, using rheometry. The reaction induced phase separation of the PS phase in the epoxy matrix was carefully explored through rheological measurements. PVT measurements during curing were carried out to understand the volume shrinkage of the blend, confirming that shrinkage behaviour is related to the block copolymer phase separation process during curing. The volume shrinkage was found to be maximum in the case of blends with unmodified SBS, where a heterogeneous morphology was observed, while a decrease in the shrinkage was evidenced in the case of SBS epoxidation. It could be explained by two effects: (1) solubility of the epoxidised block copolymer in the DGEBA leads to the formation of nanoscopic domains upon

  6. From Fresh to Marine Waters

    DEFF Research Database (Denmark)

    Gonçalves-Araujo, Rafael; Stedmon, Colin; Heim, Birgit

    2015-01-01

    Connectivity between the terrestrial and marine environment in the Artic is changing as a result of climate change, influencing both freshwater budgets and the supply of carbon to the sea. This study characterizes the optical properties of dissolved organic matter (DOM) within the Lena Delta region...... and evaluates the behavior of DOM across the fresh water-marine gradient. Six fluorescent components (four humic-like; one marine humic-like; one protein-like) were identified by Parallel Factor Analysis (PARAFAC) with a clear dominance of allochthonous humic-like signals. Colored DOM (CDOM) and dissolved...... organic carbon (DOC) were highly correlated and had their distribution coupled with hydrographical conditions. Higher DOM concentration and degree of humification were associated with the low salinity waters of the Lena River. Values decreased towards the higher salinity Laptev Sea shelf waters. Results...

  7. Microbiological Quality of Fresh Nopal Juice

    OpenAIRE

    Ana María Hernández-Anguiano; Patricia Landa-Salgado; Carlos Alberto Eslava-Campos; Mateo Vargas-Hernández; Jitendra Patel

    2016-01-01

    The consumption of fresh nopal cactus juice is widely popular among health-conscious consumers in Mexico. The juice is prepared from fresh cladodes that have only been rinsed with tap water and are not subjected to a pasteurization or terminal bacterial reduction process. The aim of this study was to evaluate the microbial quality of commercially available fresh juices (n = 162) made with nopal in Texcoco, State of Mexico, during the summer and spring season. Standard microbiological methods,...

  8. Sulfonation and characterization of styrene-indene copolymers for the development of proton conducting polymer membranes

    Directory of Open Access Journals (Sweden)

    Cristiane M. Becker

    2012-01-01

    Full Text Available The aim of this work is to obtain polymer precursors based on styrene copolymers with distinct degrees of sulfonation, as an alternative material for fuel cell membranes. Acetyl sulfate was used to carry out the sulfonation and the performance of the polyelectrolyte was evaluated based on the content of acid polar groups incorporated into the macromolecular chain. Polymeric films were produced by blending the sulfonated styrene-indene copolymer with poly(vinylidene fluoride. The degree of sulfonation of the polymer was strongly affected by the sulfonation reaction parameters, with a direct impact on the ionic exchange capacity and the ionic conductivity of the sulfonated polymers and the membranes obtained from them. The films produced with the blends showed more suitable mechanical properties, although the conductivity of the membranes was still lower than that of commercially available membranes used in fuel cells.

  9. Low metal loading catalysts used for the selective hydrogenation of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Badano, Juan; Lederhos, Cecilia; Quiroga, Monica; L' Argentiere, Pablo [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Santa Fe (Argentina). Universidad Nacional del Litoral. Inst. de Investigaciones en Catalisis y Petroquimica; Coloma-Pascual, Fernando [Universidad de Alicante (Spain). Facultad de Ciencias. Servicios Tecnicos de Investigacion

    2010-07-01

    A series of Group VIII metal catalysts was obtained for the semi-hydrogenation of styrene. Catalysts were characterized by Hydrogen Chemisorption, TPR and XPS. Palladium, rhodium and platinum low metal loading prepared catalysts presented high activity and selectivity (ca. 98%) during the semi-hydrogenation of styrene, being palladium the most active catalyst. The ruthenium catalyst also presented high selectivity (ca. 98%), but the lowest activity. For the palladium catalyst, the influence of the precursor salt and of the reduction temperature on the activity and selectivity were studied. The following activity series was obtained: PdN-423 > PdCl-673 > PdCl-373> PtCl-673 > RhCl-673 >> RuCl-673. As determined by XPS, differences in activity could be attributed, at least in part, to electronic effects (author)

  10. Radiation grafting of styrene onto polypropylene fibres by a 10 MeV electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Vahdat, A. [Textile Engineering Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Bahrami, Hajir [Textile Engineering Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)]. E-mail: hajirb@aut.ac.ir; Ansari, N. [Textile Engineering Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Ziaie, F. [Yazd Radiation Processing Centre, Yazd (Iran, Islamic Republic of)

    2007-05-15

    The radiation-induced graft copolymerization is an effective method for modification of the chemical and physical properties of polypropylene. Graft copolymerization of styrene onto polypropylene fibers has been studied by simultaneous irradiation method, using a 10 MeV electron beam. Samples were irradiated in an environment of nitrogen gas. The effects of radiation dose and styrene concentration in methanol, on the grafting yield were investigated. The effects of polyfunctional monomer, i.e., trimethylopropane trimethacrylate (TMPTMA) and acid (sulfuric acid) on the grafting yield were also examined. The grafted samples were then sulfonated and allowed to react with solution of a basic dye. The samples were characterized by mechanical properties and thermal stability. The mechanical properties of the radiated samples were reduced and the grafted samples had lower mechanical properties.

  11. Matrix-assisted laser desorption/ionization-collision induced dissociation of poly(styrene).

    Science.gov (United States)

    Jackson, A T; Yates, H T; Scrivens, J H; Green, M R; Bateman, R H

    1998-04-01

    Matrix-assisted laser desorption/ionization-collision induced dissociation (MALDI-CID) has been employed for the analysis of poly(styrene) in a tandem hybrid sector-time of flight instrument. Spectra are shown for adducts of poly(styrene) with copper and silver ions. The distributions of fragment ion peaks were found to be consistent from precursor ions containing both metal ions. It is shown how the masses of the end groups of the polymer may be inferred from the mass-to-charge ratios of two of the series of ion peaks that are seen in the MALDI-CID spectra. Mechanisms are proposed for the formation of some of the other series of ion peaks that are observed in the spectra.

  12. Styrene revisited--exposure assessment and risk estimation in reinforced plastics industry

    Energy Technology Data Exchange (ETDEWEB)

    Sorsa, M.; Anttila, A.; Jaerventaus, H.K.; Kubiak, R.; Norppa, H.; Nylander, L.; Pekari, K.; Pfaeffli, P.V.; Vainio, H. (Institute of Occupational Health, Department of Industrial Hygiene and Toxicology, Helsinki (Finland))

    1991-01-01

    A survey performed in 32 workshops in reinforced plastics industry showed the mean TWA 8 h concentration of styrene in personal air to be 43 ppm (range 5-182 ppm) among laminators and 11 ppm (range 1-133 ppm) among other workers. The biological measurement of urinary mandelic acid + phenylglyoxylic acid showed mean values of 2.4 mmol/l among laminators without respirators and 1.3 mmol/l when respirators were used. No effects of work related exposure were detected in the cytogenetic parameters, chromosome aberrations, sister chromatid exchanges or micronuclei analyzed in peripheral blood lymphocytes. Grading of the exposure on the basis of lamination method, years of exposure, daily laminating time, air styrene concentration and urinary mandelic acid among laminators, neither revealed any dose dependency.

  13. Production of Natural Rubber Grafted Styrene Copolymer Latex as Water Base Coatings

    Directory of Open Access Journals (Sweden)

    M Utama

    2006-07-01

    Full Text Available Twelve kinds formulation of natural rubber grafted copolymer styrene (NR-g-S prepared by gamma radiation co-polymerization technique has been carried out. The characteristic of NR-g-S and its water base coating such as molecular structure, particle size, and the properties of latex and its film were evaluated. The results showed that the NR-g-S latex as a water base coating has low viscosity, height strength, good grease resistance, good flexibility, good aging and corrosion resistance on concrete cement and metal. The average particle size is between 270-300 nm, and the bonding between poly-isoprene of NRL and styrene molecules were grafted copolymer

  14. Glycophorin A somatic cell mutation frequencies in Finnish reinforced plastics workers exposed to styrene.

    Science.gov (United States)

    Bigbee, W L; Grant, S G; Langlois, R G; Jensen, R H; Anttila, A; Pfäffli, P; Pekari, K; Norppa, H

    1996-10-01

    We have used the glycophorin A (GPA) in vivo somatic cell mutation assay to assess the genotoxic potential of styrene exposure in 47 reinforced plastics workers occupationally exposed to styrene and 47 unexposed controls matched for age, gender, and active smoking status. GPA variant erythrocyte frequencies (Vf), reflecting GPA allele loss (phi/N) and allele loss and duplication (N/N) somatic mutations arising in vivo in the erythroid progenitor cells of individuals of GPA M/N heterozygous genotype, were flow cytometrically determined in peripheral blood samples from these subjects. Measurements of styrene exposure of the workers at the time of blood sampling showed a mean 8-h time-weighted average (TWA8-h) styrene concentration of 155 mg/m3 (37 ppm) in the breathing zone. Mean urinary concentrations of the styrene metabolites mandelic acid (MA) and mandelic acid plus phenyl glyoxylic acid (MA+PGA) were 4.4 mmol/liter (after workshift) and 2.1 mmol/liter (next morning), respectively. Multivariate analysis of covariance on log-transformed GPA Vf data with models allowing adjustment for age, gender, smoking status, and styrene exposure showed that N/N Vf were nearly significantly increased among all of the exposed workers (adjusted geometric mean, 6.3 per million versus 5.0 in the controls; P = 0.058) and were statistically significantly elevated (adjusted geometric mean, 6.8 versus 5.0 in the controls; P = 0.036) among workers classified into a high-exposure group according to personal TWA8-h concentration of styrene in the breathing zone of > or = 85 mg/m3 (20 ppm; Finnish threshold limit value). Women in this high exposure group showed especially elevated N/N Vf (adjusted geometric mean 8.5 versus 5.3 in control women; P = 0.020); this elevation was also significant if urinary MA+PGA of > or = 1.2 mmol/liter was used as the basis of classification (adjusted geometric mean, 8.3; P = 0.030). The occupational exposure could not be shown to influence phi/N Vf

  15. Systematic Study of the Content of Phytochemicals in Fresh and Fresh-Cut Vegetables

    Directory of Open Access Journals (Sweden)

    María Isabel Alarcón-Flores

    2015-05-01

    Full Text Available Vegetables and fruits have beneficial properties for human health, because of the presence of phytochemicals, but their concentration can fluctuate throughout the year. A systematic study of the phytochemical content in tomato, eggplant, carrot, broccoli and grape (fresh and fresh-cut has been performed at different seasons, using liquid chromatography coupled to triple quadrupole mass spectrometry. It was observed that phenolic acids (the predominant group in carrot, eggplant and tomato were found at higher concentrations in fresh carrot than in fresh-cut carrot. However, in the case of eggplant, they were detected at a higher content in fresh-cut than in fresh samples. Regarding tomato, the differences in the content of phenolic acids between fresh and fresh-cut were lower than in other matrices, except in winter sampling, where this family was detected at the highest concentration in fresh tomato. In grape, the flavonols content (predominant group was higher in fresh grape than in fresh-cut during all samplings. The content of glucosinolates was lower in fresh-cut broccoli than in fresh samples in winter and spring sampling, although this trend changes in summer and autumn. In summary, phytochemical concentration did show significant differences during one-year monitoring, and the families of phytochemicals presented different behaviors depending on the matrix studied.

  16. IMPROVING OF RECLAIMED ASPHALT PAVEMENTS USING STYRENE-BUTYL ACRYLATE POLYMER

    OpenAIRE

    Abdelzaher E. A. Mostafa; Nasser, A M

    2017-01-01

    According to the most recent surveys, the European area produced 265 mil tons of asphalt for road applications in 2014, while the amount of available Reclaimed Asphalt Pavement (RAP) was more than 50 mil tons. The use of RAP in new blended mixes reduces the need of neat bitumen, making RAP recycling economically attractive. This study investigates the potential use of styrene-bacrylate polymer and extracted Reclaimed Asphalt Pavement (RAP) in Hot Mix Asphalt (HMA) with different percentages b...

  17. Solvent and irradiation doses effects on the ion exchange capacity of sulfonated styrene grafted PVDF

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Polymers exhibiting ion exchange capacity are studied for many years due to their application in several fields, such as membranes for proton exchange fuel cells, filtration membranes, heavy ions recovery and artificial muscles and sensors. Radiation induced grafting followed by sulfonation is a well-known way to obtain ion exchange polymers. Fluorinated polymers are frequently used as polymeric matrix for grafting due to their excellent physicochemical properties. Radiation induced grafting of styrene into poly (vinylidene fluoride) (PVDF) by simultaneous method in 1:1 styrene/toluene or styrene/N,N-dimethylformamide solutions was studied. Irradiations were performed under nitrogen atmosphere, room temperature and at doses of 5, 10 and 20 kGy with dose rate of 5 kGy.h{sup -1} from a {sup 60}Co gamma source. After washing, grafted materials were sulfonated in 10% chlorosulfonic acid/1,2-dichloroethane solutions for 4 h at room temperature. Characterization shows that increasing irradiation dose corresponds to increases in the grafting yield (GY %) gravimetrically calculated and these different solvents shows different grafting behaviors. Toluene allows no more than 3 % of grafting while DMF allows up to 55 % of grafting in the same condition. Grafting in toluene solution occurs on the surface and in DMF solution it occurs in the bulk, as confirmed by SEM. Both irradiation doses and solvent used have direct effects in the ion exchange capacities (calculated after titrations). FT-IR spectra exhibit new peaks after grafting and after sulfonation, attributed to grafted monomer and sulfonic groups attached to the styrene. DSC shows differences in thermal behavior of the polymer before and after each step. (author)

  18. Functionalization of cross-linked poly(styrene) in the preparation of a PET target material

    Energy Technology Data Exchange (ETDEWEB)

    Zippi, E.M.; Grover, John; Valiulis, M.B.; Tibbets, Cynthia [Louisiana State Univ., Shreveport, LA (United States). Dept. of Chemistry and Physics; Kabalka, G.W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemistry

    1996-05-01

    In an effort to prepare an improved carbon-rich target material for the generation of [{sup 13}N]ammonia for use in PET, styrene was polymerized and cross-linked with various percentages of divinylbenzene(DVB). The resulting copolymers were then sulfonated and nitrated and the degree of substitution was determined by elemental analysis. As expected, increased levels of DVB sterically hindered substitution of the aromatic ring. (Author).

  19. High Solid Contents Copoly (Styrene/Butyl Acrylate)-Cloisite 30B Nanocomposites

    OpenAIRE

    M. Mirzataheri

    2013-01-01

    Higher solid contents (20 % and 40 %) nanocomposites of poly (styrene-co-butyl acrylate) including higher content of Cloisite 30B (7 wt% and 10 wt %) were prepared via miniemulsion polymerization. Stability of the final latexes proved outstanding combination of polymerization procedure and surfactants. Morphological studies revealed by TEM, SAX and XRD showed three structures of core-shell, armored and individual dispersion of clay layers within the polymer particles. The effect of Cloisite 3...

  20. Dielectric study of Poly(styrene- co -butadiene) Composites with Carbon Black, Silica, and Nanoclay

    KAUST Repository

    Vo, Loan T.

    2011-08-09

    Dielectric spectroscopy is used to measure polymer relaxation in styrene-butadiene rubber (SBR) composites. In addition to the bulk polymer relaxation, the SBR nanocomposites also exhibit a slower relaxation attributed to polymer relaxation at the polymer-nanoparticle interface. The glass transition temperature associated with the slower relaxation is used as a way to quantify the interaction strength between the polymer and the surface. Comparisons were made among composites containing nanoclay, silica, and carbon black. The interfacial relaxation glass transition temperature of SBR-clay nanocomposites is more than 80 °C higher than the SBR bulk glass transition temperature. An interfacial mode was also observed for SBR-silica nanocomposites, but the interfacial glass transition temperature of SBR-silica nanocomposite is somewhat lower than that of clay nanocomposites. An interfacial mode is also seen in the carbon black filled system, but the signal is too weak to analyze quantitatively. The interfacial polymer relaxation in SBR-clay nanocomposites is stronger compared to both SBR-carbon black and SBR-silica composites indicating a stronger interfacial interaction in the nanocomposites containing clay. These results are consistent with dynamic shear rheology and dynamic mechanical analysis measurements showing a more pronounced reinforcement for the clay nanocomposites. Comparisons were also made among clay nanocomposites using different SBRs of varying styrene concentration and architecture. The interfacial glass transition temperature of SBR-clay nanocomposites increases as the amount of styrene in SBR increases indicating that styrene interacts more strongly than butadiene with clay. © 2011 American Chemical Society.

  1. Feasibility of Using Foamed Styrene Maleic Anhydride (SMA) Co-polymer in Wood Based Composites

    OpenAIRE

    Mustafa Zor; Nurgul Tankut; Alper Kiziltas; Douglas Gardner; Hikmet Yazici

    2017-01-01

    Wood plastic composites (WPCs) have often been used in consumer applications, automotive industry and exterior construction. WPCs consist mostly of wood and thermoplastic polymer. WPCs can have superior outdoor durability and much lower maintenance costs than regular wood. WPCs can be used instead of wood. Styrene maleic anhydride (SMA) is used in plastic composites for the automotive industry and also in engineering applications. SMA wood composites, as one of the WPCs using wood fibers as r...

  2. Impact of noise or styrene exposure on the kinetics of presbycusis.

    Science.gov (United States)

    Campo, Pierre; Venet, Thomas; Rumeau, Cécile; Thomas, Aurélie; Rieger, Benoît; Cour, Chantal; Cosnier, Frédéric; Parietti-Winkler, Cécile

    2011-10-01

    Presbycusis, or age-related hearing loss is a growing problem as the general population ages. In this longitudinal study, the influence of noise or styrene exposure on presbycusis was investigated in Brown Norway rats. Animals were exposed at 6 months of age, either to a band noise centered at 8 kHz at a Lex,8h = 85 dB (86.2 dB SPL for 6 h), or to 300 ppm of styrene for 6 h per day, five days per week, for four weeks. Cubic distortion product otoacoustic emissions (2f1-f2 DPOAEs) were used to test the capacity of the auditory receptor over the lifespan of the animals. 2f1-f2DPOAE measurements are easy to implement and efficiently track the age-related deterioration of mid- and high-frequencies. They are good indicators of temporary auditory threshold shift, especially with a level of primaries close to 60 dB SPL. Post-exposure hearing defects are best identified using moderate, rather than high, levels of primaries. Like many aging humans, aging rats lose sensitivity to high-frequencies faster than to medium-frequencies. Although the results obtained with the styrene exposure were not entirely conclusive, histopathological data showed the presbycusis process to be enhanced. Noise-exposed rats exhibit a loss of spiral ganglion cells from 12 months and a 7 dB drop in 2f1-f2DPOAEs at 24 months, indicating that even moderate-intensity noise can accelerate the presbycusis process. Even though the results obtained with the styrene exposure are less conclusive, the histopathological data show an enhancement of the presbycusis process. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Performance Analysis of Styrene Butadiene Rubber-Latex on Cement Concrete Mixes.

    OpenAIRE

    Er. Kapil Soni; Dr. Y.P Joshi

    2014-01-01

    To improve the performance of concrete, polymers are mixed with concrete. It has been observed that polymer-modified concrete (PMC) is more durable than conventional concrete due to superior strength and high durability. In this research, effect of Styrene-Butadiene Rubber (SBR) latex on compressive strength and flexural strength of concrete has been studied and also the optimum polymer (SBR-Latex) content for concrete is calculated. This research was carried out to establish t...

  4. Microstructural analysis of carbon nanomaterials produced from pyrolysis/combustion of Styrene-Butadiene-Rubber (SBR)

    OpenAIRE

    Alves, Joner Oliveira; Zhuo, Chuanwei; Levendis, Yiannis Angelo; Tenório, Jorge Alberto Soares

    2011-01-01

    Styrene-Butadiene-Rubber (SBR) is a synthetic rubber copolymer used to fabricate several products. This study aims to demonstrate the use of SBR as feedstock for carbon nanomaterials (nanofibers and nanotubes) growth, and therefore to establish a novel process for destination of waste products containing SBR. A three stage electrically heated flow reactor was used. Small pellets of rubber were pyrolyzed at a temperature of 1000 ºC. The pyrolyzates were mixed with oxygen-containing gases and w...

  5. Mechanical and Electrical Properties of Acrylonitrile Butadiene Styrene/Melamine-Functionalized Reduced Graphene Oxide Nanocomposites.

    Science.gov (United States)

    Oh, Miae; Rajagopalan, Balasubramaniyan; Chung, Jin Suk

    2015-11-01

    Nanocomposite of acrylonitrile butadiene styrene (ABS) and melamine functionalized reduced graphene oxide (M-RGO) was prepared by solution blending. The functionalization of graphene oxide was performed with melamine to increase the compatibility between graphene sheets and the ABS matrix. The ABS/M-RGO showed improved storage modulus by 55% at 4.0 wt% of M-RGO in the glassy region and exhibited a low percolation threshold with a high electrical conductivity.

  6. Genetic Characterization of Accumulation of Polyhydroxyalkanoate from Styrene in Pseudomonas putida CA-3

    Science.gov (United States)

    O'Leary, Niall D.; O'Connor, Kevin E.; Ward, Patrick; Goff, Miriam; Dobson, Alan D. W.

    2005-01-01

    Pseudomonas putida CA-3 is capable of accumulating medium-chain-length polyhydroxyalkanoates (MCL-PHAs) when growing on the toxic pollutant styrene as the sole source of carbon and energy. In this study, we report on the molecular characterization of the metabolic pathways involved in this novel bioconversion. With a mini-Tn5 random mutagenesis approach, acetyl-coenzyme A (CoA) was identified as the end product of styrene metabolism in P. putida CA-3. Amplified flanking-region PCR was used to clone functionally expressed phenylacetyl-CoA catabolon genes upstream from the sty operon in P. putida CA-3, previously reported to generate acetyl-CoA moieties from the styrene catabolic intermediate, phenylacetyl-CoA. However, the essential involvement of a (non-phenylacetyl-CoA) catabolon-encoded 3-hydroxyacyl-CoA dehydrogenase is also reported. The link between de novo fatty acid synthesis and PHA monomer accumulation was investigated, and a functionally expressed 3-hydroxyacyl-acyl carrier protein-CoA transacylase (phaG) gene in P. putida CA-3 was identified. The deduced PhaG amino acid sequence shared >99% identity with a transacylase from P. putida KT2440, involved in 3-hydroxyacyl-CoA MCL-PHA monomer sequestration from de novo fatty acid synthesis under inorganic nutrient-limited conditions. Similarly, with P. putida CA-3, maximal phaG expression was observed only under nitrogen limitation, with concomitant PHA accumulation. Thus, β-oxidation and fatty acid de novo synthesis appear to converge in the generation of MCL-PHA monomers from styrene in P. putida CA-3. Cloning and functional characterization of the pha locus, responsible for PHA polymerization/depolymerization is also reported and the significance and future prospects of this novel bioconversion are discussed. PMID:16085828

  7. Fe(II)/Fe(III)-Catalyzed Intramolecular Didehydro-Diels-Alder Reaction of Styrene-ynes.

    Science.gov (United States)

    Mun, Hyeon Jin; Seong, Eun Young; Ahn, Kwang-Hyun; Kang, Eun Joo

    2018-02-02

    The intramolecular didehydro-Diels-Alder reaction of styrene-ynes was catalyzed by Fe(II) and Fe(III) to produce various naphthalene derivatives under microwave heating conditions. Mechanistic calculations found that the Fe(II) catalyst activates the styrenyl diene in an inverse-electron-demand Diels-Alder reaction, and the consecutive dehydrogenation reaction can be promoted by either Fe(II)-catalyzed direct dehydrogenation or an Fe(III)-catalyzed rearomatization/dehydrogenation pathway.

  8. The effect of multifunctional monomers/oligomers Additives on electron beam radiation crosslinking of poly (styrene-block-isoprene/butadiene-block-styrene) (SIBS)

    Science.gov (United States)

    Wu, Jinping; Soucek, Mark D.

    2016-02-01

    The effect of multifunctional monomers or oligomers (MFM/O) additives on electron beam (E-beam) radiation induced crosslinking of poly (styrene-block-isoprene/butadiene-block-styrene) (SIBS) was studied. Ten types of MFM/O were investigated, including trimethylolpropane trimethacrylate (TMPTMA), trimethylolpropane triacrylate (TMPTA), triallyl cyanurate (TAC), polybutadiene diacrylate (PB-diacrylate), ethylene glycol dimethylacrylate (EGDMA), butylene glycol dimethacrylate (BGDMA), 1,2-polybutadiene. The effects of MFM/O concentration and E-beam radiation dose on properties of SIBS were studied including tensile strength, elongation-at-break, modulus, gel content, equilibrium swelling and crosslink density. TMPTA significantly improved the tensile modulus and crosslink density of SIBS. SIBS with TMPTMA and TMTPMA with inhibitor showed a 50% increase in tensile strength. The solubility of MFM/O in SIBS was also investigated by a selective swelling method. The MFM/O were found to be soluble in both phases of SIBS. The viscosity of SIBS with methacrylate type MFM/O was stable at 200 °C.

  9. Shape Memory Polymer Composites of Poly(styrene-b-butadiene-b-styrene Copolymer/Liner Low Density Polyethylene/Fe3O4 Nanoparticles for Remote Activation

    Directory of Open Access Journals (Sweden)

    Yongkun Wang

    2016-11-01

    Full Text Available Magnetically sensitive shape memory poly(styrene-b-butadiene-b-styrene copolymer (SBS/liner low density polyethylene (LLDPE composites filled with various contents of Fe3O4 nanoparticles were prepared. The influence of the Fe3O4 nanoparticles content on the thermal properties, mechanical properties, fracture morphology, magnetic behavior, and shape memory effect of SBS/LLDPE/Fe3O4 composites was systematically studied in this paper. The results indicated that homogeneously dispersed Fe3O4 nanoparticles ensured the uniform heat generation and transfer in the alternating magnetic field, and endowed the SBS/LLDPE/Fe3O4 composites with an excellent magnetically responsive shape memory effect. When the shape memory composites were in the alternating magnetic field (f = 60 kHz, H = 21.21 kA·m−1, the best shape recovery ratio reached 99%, the shape retention ratio reached 99.4%, and the shape recovery speed increased significantly with the increment of Fe3O4 nanoparticles. It is anticipated that tagging products with this novel shape memory composite is helpful for the purpose of an intravascular delivery system in Micro-Electro-Mechanical System (MEMS devices.

  10. Effect of operating temperature on styrene mass transfer characteristics in a biotrickling filter.

    Science.gov (United States)

    Parnian, Parham; Zamir, Seyed Morteza; Shojaosadati, Seyed Abbas

    2017-05-01

    To study the effect of operating temperature on styrene mass transfer from gas to liquid phase in biotrickling filters (BTFs), overall mass transfer coefficient (KL a) was calculated through fitting test data to a general mass balance model under abiotic conditions. Styrene was used as the volatile organic compound and the BTF was packed with a mixture of pall rings and pumice. Operating temperature was set at 30°C and 50°C for mesophilic and thermophilic conditions, respectively. KL a values increased from 54 to 70 h-1 at 30°C and from 60 to 90 h-1 at 50°C, respectively, depending on the countercurrent gas to liquid flow ratio that varied in the range of 7.5-32. Evaluation of styrene mass transfer capacity (MTC) showed that liquid-phase mass transfer resistance decreased as the flow ratio increased at constant temperature. MTC also decreased with an increase in operating temperature. Both gas-liquid partition coefficient and KL a increased with increasing temperature; however the effect on gas-liquid partition coefficient was more significant and served to increase mass transfer limitations. Thermophilic biofiltration on the one hand increases mass transfer limitations, but on the other hand may enhance the biodegradation rate in favor of enhancing BTFs' performance.

  11. The electrospinning of the copolymer of styrene and butyl acrylate for its application as oil absorbent.

    Science.gov (United States)

    Xu, Naiku; Cao, Jipeng; Lu, Yuyao

    2016-01-01

    Electrospun polystyrene materials have been employed as oil absorbents, but they have visible drawbacks such as poor strength at low temperature and unreliable integrity because of brittleness and insufficient cohesive force among fibers. Butyl acrylate can polymerize into flexible chains, and its polymer can be used as elastomer and adhesive material. Thereby it is possible to obtain the material that has better performance in comparison with electrospun polystyrene material through the electrospinning of the copolymer of styrene and butyl acrylate. In this work, a polymer was synthesized through suspension polymerization by using styrene and butyl acrylate as comonomers. The synthesis of the copolymer of styrene and butyl acrylate was verified through dissolution and hydrolysis experimental data; as well through nuclear magnetic resonance spectrometry. The viscous flow activation energy of the solution consisting of copolymer and N, N-dimethylformamide was determined via viscosity method and then adopted to establish the entanglement characteristics of butyl acrylate's chain segments. Finally, in order to electrospin the copolymer solution into fibrous membrane, the effects of monomer feed ratio and spinning parameters were investigated. The prepared fibrous membrane was found to have a potential use as oil absorbent.

  12. Copolymerization kinetics of methyl methacrylate-styrene obtained by PLP-MALDI-ToF-MS.

    Science.gov (United States)

    Willemse, Robin X E; van Herk, Alex M

    2006-04-05

    The combination of MALDI-ToF-MS and pulsed laser polymerization has been used to study the propagation rate coefficients for the copolymer system styrene-methyl methacrylate. For the first time, complete information regarding mode of termination, reactivity of photoinitiator-derived radicals, copolymer molecular mass, chemical composition, and copolymerization rates is obtained interrelated. The polymerizations were carried out in bulk with varying styrene concentrations at a temperature of 15.2 degrees C by an excimer pulsed laser with varying frequencies. Both chemical composition distributions and molecular weight distributions were determined by MALDI-ToF-MS. The data were fitted to the implicit penultimate unit model and have resulted in new point estimates of the monomer and radical reactivity ratios for the copolymer system styrene-methyl methacrylate: r(St) = 0.517, r(MMA) = 0.420, s(St) = 0.296, s(MMA) = 0.262. Comparison between Monte Carlo simulations and the obtained results further confirmed the very successful combination of pulsed laser copolymerization experiments with MALDI-ToF-MS. The obtained results are believed to be the most accurate and complete set of copolymerization parameters to date.

  13. New highly fluorinated styrene-based materials with low surface energy prepared by ATRP

    DEFF Research Database (Denmark)

    Borkar, Sachin; Jankova Atanasova, Katja; Siesler, Heinz W

    2004-01-01

    2,3,5,6-Tetrafluoro-4-(2,2,3,3,3-pentafluoropropoxy)styrene (TF(F-5)S) and 2,3,5,6-tetrafluoro-4-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctaoxy)styrene (TF(F,5)S) are prepared by nucleophilic substitution of 2,3,4,5,6-pentafluorostyrene. The neat monomers are subjected to atom transfer...... radical polymerization (ATRP) at 110 degreesC to high conversions in relatively short times, 10-120 min; TF(F-5)S is additionally polymerized at 70 and 90 degreesC. Block copolymers with styrene are prepared by the macroinitiator approach. All polymers, in the number-average molecular weight range from...... than 10 mol %. The fluorinated side chains of P(TF(F-5)S) and P(TF(F-15)S) enrich the surface of thin films, which results in an advancing water contact angle of 117degrees and 122degrees, respectively. Both XPS analyses and contact angle measurements strongly imply that the fluorinated parts...

  14. Polybutadiene and Styrene-Butadiene rubbers for high-dose dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Lucas N. [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias-IFG,Campus Goiania, Goiania -GO (Brazil); Instituto de Pesquisas Energeticas e Nucleares -IPEN, Sao Paulo-SP (Brazil); Vieira, Silvio L. [Instituto de Fisica, Universidade Federal de Goias-UFG, Campus Samambaia, Goiania-GO (Brazil); Schimidt, Fernando [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias-IFG,Campus Inhumas, Inhumas-GO (Brazil); Antonio, Patricia L.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares -IPEN, Sao Paulo-SP (Brazil)

    2015-07-01

    Polybutadiene and Styrene-Butadiene are synthetical rubbers used widely for pneumatic tires manufacturing. In this research, the dosimeter characteristics of those rubbers were studied for application in high-dose dosimetry. The rubber samples were irradiated with doses of 10 Gy up to 10 kGy, using a {sup 60}Co Gamma Cell-220 system (dose rate of 1.089 kGy/h) and their readings were taken on a Fourier Transform Infrared Spectroscopy-FTIR system (model Frontier/Perkin Elmer). The ratios of two absorbance peaks were taken for each kind of rubber spectrum, Polybutadiene (1306/1130 cm{sup -1}) and Styrene-Butadiene (1449/1306 cm{sup -1}). The ratio calculated was used as the response to the irradiation, and is not uniform across the sample. From the results, it can be concluded for both rubbers: a) the dose-response curves may be useful for high-dose dosimetry (greater than 250 Gy); b) their response for reproducibility presented standard deviations lower than 2.5%; c) the relative sensitivity was higher for Styrene-Butadiene (1.86 kGy{sup -1}) than for Polybutadiene (1.81 kGy{sup -1}), d) for doses of 10 kGy to 200 kGy, there was no variation in the dosimetric response. Both types of rubber samples showed usefulness as high-dose dosimeters. (authors)

  15. Studies of electron-beam irradiation on ethylene-styrene interpolymers

    CERN Document Server

    Liu, I C

    2002-01-01

    Electron-beam irradiation-induced structural and properties changes on ethylene-styrene interpolymers (ESI) have been studied at electron doses ranging from 0 to 200 kGy. The amounts of species generated by irradiation such as hydroxyls, hydroperoxides, carbonyls and unsaturated double bonds have been analyzed using ATR-FTIR. While the structural changes are minimal for ESI69 comprising 69 wt.% styrene regardless of the dose level, the changes for ESI40 comprising 40 wt.% styrene are dose dependent and reaches a maximum at a dose of 100 kGy. Gel permeation chromatography analysis indicates that macromolecular chain scission occurs at low irradiation dose and crosslinking dominates at high irradiation doses. The average molecular weights between crosslinks, M sub C 's, have been calculated using the Flory-Rehner equation based on data collected from solvent extraction experiments. The M sub C 's of ESI40 samples are much smaller than those of ESI69 samples. Irradiated ESI samples have higher glass transition t...

  16. Thermodynamics of coil-hyperbranched poly(styrene-b-acrylated epoxidized soybean oil) block copolymers

    Science.gov (United States)

    Lin, Fang-Yi; Hohmann, Austin; Hernández, Nacú; Cochran, Eric

    Here we present the phase behavior of a new type of coil-hyperbranched diblock copolymer: poly(styrene- b-acrylated epoxidized soybean oil), or PS-PAESO. PS-PAESO is an example of a biorenewable thermoplastic elastomer (bio-TPE). To date, we have shown that bio-TPEs can be economical commercial substitutes for their petrochemically derived analogues--such as poly(styrene- b-butadiene- b-styrene) (SBS)--in a range of applications including pressure sensitive adhesives and bitumen modification. From a polymer physics perspective, PS-PAESO is an interesting material in that it couples a linear coil-like block with a highly branched block. Thus in contrast to the past five decades of studies on linear AB diblock copolymers, coil-hyperbranched block copolymers are relatively unknown to the community and can be expected to deviate substantially from the standard ``universal'' phase behavior in the AB systems. To explore these new materials, we have constructed a library of PS-PAESO materials spanning a range of molecular weight and composition values. The phase transition behavior and the morphology information will be interpreted by isochronal temperature scanning in dynamic shear rheology, small angle X-ray scattering and the corresponding transmission electron microscopy.

  17. Dynamic ad hoc networks

    CERN Document Server

    Rashvand, Habib

    2013-01-01

    Motivated by the exciting new application paradigm of using amalgamated technologies of the Internet and wireless, the next generation communication networks (also called 'ubiquitous', 'complex' and 'unstructured' networking) are changing the way we develop and apply our future systems and services at home and on local, national and global scales. Whatever the interconnection - a WiMAX enabled networked mobile vehicle, MEMS or nanotechnology enabled distributed sensor systems, Vehicular Ad hoc Networking (VANET) or Mobile Ad hoc Networking (MANET) - all can be classified under new networking s

  18. Adding and Deleting Images

    Science.gov (United States)

    Images are added via the Drupal WebCMS Editor. Once an image is uploaded onto a page, it is available via the Library and your files. You can edit the metadata, delete the image permanently, and/or replace images on the Files tab.

  19. What Value "Value Added"?

    Science.gov (United States)

    Richards, Andrew

    2015-01-01

    Two quantitative measures of school performance are currently used, the average points score (APS) at Key Stage 2 and value-added (VA), which measures the rate of academic improvement between Key Stage 1 and 2. These figures are used by parents and the Office for Standards in Education to make judgements and comparisons. However, simple…

  20. Adding an extra storey

    DEFF Research Database (Denmark)

    Engelmark, Jesper; Dahl, Torben; Melgaard, Ebbe

    2007-01-01

    of them had to be renovated after a shorter period. In stead of just replacing the original roof with a new one, it is now a days rather common to ad an extra storey where that is possible according to local planning. The reason is as a rule based on economical benefits, but very often this extra storey...

  1. Freshness evaluation of refreshing creams: influence of two types of peppermint oil and emulsion formulation.

    Science.gov (United States)

    Damonte, Silvia Perez; Selem, Claudia; Parente, Maria Emma; Ares, Gastón; Manzoni, Ana Victoria

    2011-01-01

    The aim of the present work was to study the influence of emulsion composition and two types of peppermint oil (common and dementholated) on freshness perception (skin feel) of refreshing creams, as evaluated by trained assessors and two consumer panels. Both common peppermint oil (PO) and dementholated peppermint oil (DPO) were added in a 1% concentration to two base emulsions formulated with high (emulsion A) and low (emulsion B) concentration of apolar components. The samples' freshness was evaluated by a panel of trained assessors and by consumers. Results showed that the freshness sensation was higher when formulation B was considered, which indicates that its low proportion of apolar components might have enhanced peppermint oil liberation and penetration into the skin, increasing freshness perception. On the other hand, no significant differences in freshness intensity after 5 min of application were found between creams formulated containing DPO or PO, suggesting that other components different from menthol might have contributed to the immediate perception of freshness. Results from the present work showed that emulsion formulation has a great effect on freshness perception, suggesting that different formulations should be considered and tested when developing refreshing cosmetics.

  2. A model for discrimination freshness of shrimp

    Directory of Open Access Journals (Sweden)

    Linong Du

    2015-12-01

    Full Text Available The shrimp is popular for its nutrition and dainty, however, it is easy to decay, and its freshness degrades, so, it is important to assess its freshness. The shrimp gives off unpleasant odor with its freshness change, detecting its odor difference can evaluate its freshness. The feasibility of using electronic nose for evaluating the freshness of shrimp (Penaeus vanmamei is explored in this paper. The odor of shrimp, stored at 5 °C, was detected by the electronic nose. Combined with the sensory evaluation and TVBN, a model based on the electronic nose was constructed to evaluate the shrimp freshness. In principal components analysis, the first three principal components accounted for 86.97% of total variation, and they are used to establish a model to estimate the shrimp freshness with Fisher Liner Discriminant. The discriminant rates were 98.3% for 120 modeling sample data, and 91.7% for 36 testing sample data. The model could be easily used to evaluate the freshness of shrimp with better accuracy.

  3. What determines fresh fish consumption in Croatia?

    Science.gov (United States)

    Tomić, Marina; Matulić, Daniel; Jelić, Margareta

    2016-11-01

    Although fresh fish is widely available, consumption still remains below the recommended intake levels among the majority of European consumers. The economic crisis affects consumer food behaviour, therefore fresh fish is perceived as healthy but expensive food product. The aim of this study was to determine the factors influencing fresh fish consumption using an expanded Theory of Planned Behaviour (Ajzen, 1991) as a theoretical framework. The survey was conducted on a heterogeneous sample of 1151 Croatian fresh fish consumers. The study investigated the relationship between attitudes, perceived behavioural control, subjective norm, moral obligation, involvement in health, availability, intention and consumption of fresh fish. Structural Equation Modeling by Partial Least Squares was used to analyse the collected data. The results indicated that attitudes are the strongest positive predictor of the intention to consume fresh fish. Other significant predictors of the intention to consume fresh fish were perceived behavioural control, subjective norm, health involvement and moral obligation. The intention to consume fresh fish showed a strong positive correlation with behaviour. This survey provides valuable information for food marketing professionals and for the food industry in general. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Consumers' store choice behavior for fresh food

    NARCIS (Netherlands)

    Meulenberg, M.T.G.; Trijp, van J.C.M.

    1991-01-01

    Consumers' preference for fresh food stores is analyzed. In particular the choice between supermarkets and specialized shops for purchasing fresh food is analyzed. Attention is given to the factors influencing this choice. For this purpose a number of research questions with respect to store choice

  5. Pork loin quality is not indicative of fresh belly or fresh and cured ham quality

    Science.gov (United States)

    The objective was to characterize the relationship between fresh 30 loin quality and with fresh belly or fresh and cured ham quality. Pigs raised in 8 barns representing two seasons [cold (n = 4,290) and hot (n = 3,394)] and two production focuses [lean (n = 3,627) and quality n = 4,057)] were used....

  6. Color vision loss among styrene-exposed workers neurotoxicological threshold assessment.

    Science.gov (United States)

    Campagna, D; Gobba, F; Mergler, D; Moreau, T; Galassi, C; Cavalleri, A; Huel, G

    1996-01-01

    Styrene represents nowadays one of the most used organic solvent. The current exposure limit proposed for this chemical differs significantly from country to country: the Threshold Limit Value-Time Weighted Average (TLV-TWA) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH) is 50 ppm while the German, Finnish and Swedish occupational exposure limit is 20 ppm. Nevertheless, effects on the nervous system were recently reported in workers exposed at TWA styrene levels below the current TLV. Neuro-optic pathways have been shown to be particularly vulnerable to organic solvent exposure. Analysis and measurements of visual functions can provide important information on early neurotoxic effects. Previous studies support the hypothesis that styrene exposure can induce a dose-dependent color vision loss. The aim of this study is to assess a threshold level below which no detectable effect occurs for color vision. We applied a sub-application of the change point problem in two-phase regression considering one phase as a constant line. In accordance with this model the maximum-likelihood technique was used as a method to examine the dose- effect relationship between external styrene exposure and chromatic discrimination. The present article presents a joint analysis of data from two previously published studies, one carried out in Canada and the other in Italy. The age and seniority of the workers from both countries were remarkably similar, as were the process type, the chemicals used and the work-tasks of exposed subjects. The mathematical method presented here shows the existence of a statistically significant threshold. This finding shows that, in fiberglass-reinforced plastics industry, visual color impairment could be significantly detected above 4 ppm (upper limit of the confidence interval at 5% = 26 ppm). The exact clinical meaning of this effect, and also the progress of the impairment in exposed workers, is still to be assessed in

  7. Biotrickling filtration of air-borne styrene: a comparison of filtration media.

    Science.gov (United States)

    Chuang, Fu-Jen; Chou, Ming-Shean; Chang, Hsiao-Yu

    2018-01-08

    This study compares the performances of fern and plastic chips as packing media for the biofiltration of a styrene-laden waste gas stream emitted in a plant for the manufacture of plastic door plates. Fern chips (with a specific surface area of 1,090 m2 m-3) and plastic chips (with a specific surface area of 610 m2 m-3) were packed into a pilot-scale with a total media volume of 50 L for the performance test. Field waste gas with styrene concentrations in the range of 161-2390 mg Am-3 (@28-30oC) was introduced to the bed and a fixed EBRT (empty bed retention time) of 21 s, a volumetric gas flow rate of 8.57 m3 hr-1, and superficial gas velocity of 53.6 m hr-1 was maintained throughout the experimental period. Nutrients containing metal salts, nitrogen, phosphorus, and milk were supplemented to the filters for maintaining the microbial activities. Results reveal that the biotrickling filter developed in this study had the highest SM elimination capacities (170 g m-3 hr for fern-chip packing and 300 g m-3 hr-1 for plastic-chip packing) among those cited in the literature. The plastic medium is a favorable substitute for endangered fern chips. The thermal-setting nature of plastic chips limits their recycle and reuse as raw materials and the study provides an opportunity for the utilization of the materials. Biotreatment of contaminants in air streams offers an inexpensive and efficient alternative to conventional technologies. Biofiltration have a great potential for the degradation of gas-borne styrene . THC removal efficiency of around 80%. The objective of this research was to compare the performances of fern chips and a kind of plastic chips as packing media for biofiltration of the styrene-laden waste gas stream emitted from cutting operations of stripes of premixed unsaturated polyester (UP) and styrene paste before hot-pressing operations for making plastic door plates. From a practical point of view, the plastic media can be a good substitute

  8. Incorporation and release of cloxacillin sodium in micelles of poly(styrene-b-2-vinyl pyridine-b-ethylene oxide).

    Science.gov (United States)

    Khanal, Anil; Nakashima, Kenichi

    2005-11-02

    A novel drug carrier system was constructed from anionic drug cloxacillin sodium (CLX) and micelle of poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO) by incorporating the former into the micelle of the latter. The incorporation of CLX into the micelle of PS-PVP-PEO was confirmed by zeta-potential measurements, dynamic light scattering (DLS), and fluorescence spectroscopy. In the absence of the anionic drug, CLX, the zeta-potential of neat PS-PVP-PEO micelle was +13 mV under aqueous acidic condition due to the presence of positive charges in the PVP unit. The addition of CLX into the micelle of PS-PVP-PEO decreased the zeta-potential of the micelle smoothly and finally led to a minimum zeta-potential around 0 mV. This fact shows that the added CLX is effectively incorporated into the PS-PVP-PEO micelle by electrostatic attraction. In concomitant with the decrease in zeta-potential, a decrease in hydrodynamic diameter from 94 to 69 nm was observed on addition of CLX to the PS-PVP-PEO micellar solution. This fact also indicates the incorporation of CLX into the PS-PVP-PEO micelles because the binding of CLX to the PVP block of the micelles induces a conformational change from an extended to a shrunken form due to the cancellation of the repulsive force in the PVP blocks by CLX. Fluorescence quenching of pyrene by CLX gave additional evidence for the effective bindings of CLX to the PS-PVP-PEO micelles. Further, release of CLX from the nanoaggregates of CLX/PS-PVP-PEO was investigated in vitro. It was found that the release kinetics of the CLX is conformed to a model based on the consecutive chemical kinetics.

  9. Ads in Indonesia

    Directory of Open Access Journals (Sweden)

    Wulan Roro Retno

    2017-01-01

    Full Text Available Cosmetics industry created the beauty myth for women through advertising. A cosmetic ad in Indonesia has spread a new concept of white skin: East Asia beauty myth. The white concept of Asia white skin basically derived from colonial legacy. The purpose of the research was analyzing the beauty myth in Indonesia ads using postcolonial perspective. The principal result brought the discourse analysis and postcolonial perspective a new insight in communication research. Particularly on media and cultural studies. Major conclusions showed that the beauty myth since the Dutch colonial period never been change. The main concept is always in colonialism’s idea: “white is better”. The West is better than the East.

  10. Management job ads

    DEFF Research Database (Denmark)

    Holmgreen, Lise-Lotte

    2014-01-01

    jobs by discursively constructing job ads that appeal to both sexes. This argument is part of the broader field of corporate social responsibility, corporate citizenship, and stakeholder management, which involves discussions of the obligations of corporations to acknowledge and mitigate......The article asks whether it is not the responsibility of corporations to address the issue of women being underrepresented in Danish management jobs. In other words, it is argued that corporations should be encouraged to engage more actively in the recruitment of both men and women for management...... the increasingly widespread impact that their activities have on communities and social structures. The article emphasises the need for more active engagement on the part of corporations by analysing the discursive construction of preferred candidates in a small sample of Danish management job ads. By means...

  11. Philosophia ad bellum

    Directory of Open Access Journals (Sweden)

    Yu. O. Loboda

    2014-06-01

    Full Text Available In the paper «Philosophia ad bellum» is being realized an attempt to classify philosophic approaches to the study of phenomenon of war by the analogy with the structure of «Just war theory» – 1. Philosophia ad bellum – «philosophy for war», where are investigated ways of using of philosophic methods of cognition in applied military sciences; 2. Philosophia supra bello – «philosophy above war», which investigates world­view, historic­philosophic, existential, logic­epistemological aspects of war; 3. Philosophia contra belli – «philosophy against war», where research of the essence of war gets its logical conclusion in grounding of the absurdity of thinking schemes which justify war as an act of violence. In the article was made historic­philosophic overview of the part «Philosophia ad bellum», where were showed tangent questions, which are considered by philosophic logic and theory of strategic intelligence. It was stated, that specialists if military intelligence admit the important role of researches in logic and theory of cognition in their professional work; were defined basic questions, which have the most essential interest for military professionals. There were analyzed ways of using of philosophic methods in developing military strategies, was made a conclusion that philosophy can be a basis of strategic failures and victories as well.

  12. Development of microporous drug-releasing films cast from artificial nanosized latexes of poly(styrene-co-methyl methacrylate) or poly(styrene-co-ethyl methacrylate).

    Science.gov (United States)

    Otto, Daniel P; Vosloo, Hermanus C M; Liebenberg, Wilna; de Villiers, Melgardt M

    2008-08-01

    Two sets of copolymers comprising of styrene and either methyl or ethyl methacrylate as comonomer were conveniently synthesized by microemulsion copolymerization. The purified materials were characterized by GPC-MALLS and were shown to form artificial nanolatexes in THF. ATR-FTIR analysis revealed differences in copolymer composition and based on the copolymer properties, a selection of copolymers was chosen to cast drug-loaded, microporous films that exhibit microencapsulation of drug agglomerates. The contact angles of the copolymers suggested potential applications in medical devices to prevent the formation of bacterial biofilms that commonly result in infections. Additionally, the different copolymeric films showed two phases of drug release characterized by a rapid initial drug release followed by a zero-order phase. Depending on the application, one could select the copolymer films that best suited the application i.e. for short-term drug release applications such as urinary catheters or long-term applications such as artificial implants.

  13. Responses of conventional and molecular biomarkers in turbot Scophthalmus maximus exposed to heavy fuel oil no. 6 and styrene.

    Science.gov (United States)

    Ruiz, Pamela; Ortiz-Zarragoitia, Maren; Orbea, Amaia; Theron, Michael; Le Floch, Stéphane; Cajaraville, Miren P

    2012-07-15

    Several accidental spills in European coastal areas have resulted in the release of different toxic compounds into the marine environment, such as heavy fuel oil type no. 6 in the "Erika" and "Prestige" oil spills and the highly toxic styrene after the loss of the "Ievoli Sun". There is a clear need to develop tools that might allow assessing the biological impact of these accidental spills on aquatic organisms. The aim of the present study was to determine the short-term effects and recovery after exposure of juvenile fish (Scophthalmus maximus) to heavy fuel oil no. 6 and styrene by using a battery of molecular, cell and tissue level biomarkers. Turbots were exposed to styrene for 7 days and to the diluted soluble fraction of the oil (10%) for 14 days, and then allowed to recover in clean seawater for the same time periods. cyp1a1 transcript was overexpressed in turbots after 3 and 14 days of exposure to heavy fuel oil, whereas ahr transcription was not modulated after heavy fuel oil and styrene exposure. pparα transcription level was significantly up-regulated after 3 days of treatment with styrene. Liver activity of peroxisomal acyl-CoA oxidase (AOX) was significantly induced after 14 days of oil exposure, but it was not affected by styrene. Hepatocyte lysosomal membrane stability (LMS) was significantly reduced after exposure to both treatments, indicating that the tested compounds significantly impaired fish health. Both AOX and LMS values returned to control levels after the recovery period. No differences in gamete development were observed between fuel- or styrene- exposed fish and control fish, and vitellogenin plasma levels were low, suggesting no xenoestrogenic effects of fuel oil or styrene. While styrene did not cause any increase in the prevalence of liver histopathological alterations, prevalence of extensive cell vacuolization increased after exposure to heavy fuel oil for 14 days. In conclusion, the suite of selected biomarkers proved to be

  14. AdS 3-manifolds and Higgs bundles

    DEFF Research Database (Denmark)

    Alessandrini, Daniele; Li, Qiongling

    2017-01-01

    In this paper we investigate the relationships between closed AdS $3$-manifolds and Higgs bundles. We have a new way to construct AdS structures that allows us to see many of their properties explicitly, for example we can recover the very recent formula by Tholozan for their volume. We give natu...

  15. Dressing phases of AdS3/CFT2

    NARCIS (Netherlands)

    Borsato, R.; Olsson Sax, O.E.; Sfondrini, A.; Stefanski, B.; Torrielli, A.

    2013-01-01

    We determine the all-loop dressing phases of the AdS3/CFT2 integrable system related to type IIB string theory on AdS3×S3×T4 by solving the recently found crossing relations and studying their singularity structure. The two resulting phases present a novel structure with respect to the ones

  16. Characterisation of recycled acrylonitrile-butadiene-styrene and high-impact polystyrene from waste computer equipment in Brazil.

    Science.gov (United States)

    Hirayama, Denise; Saron, Clodoaldo

    2015-06-01

    Polymeric materials constitute a considerable fraction of waste computer equipment and polymers acrylonitrile-butadiene-styrene and high-impact polystyrene are the main thermoplastic polymeric components found in waste computer equipment. Identification, separation and characterisation of additives present in acrylonitrile-butadiene-styrene and high-impact polystyrene are fundamental procedures to mechanical recycling of these polymers. The aim of this study was to evaluate the methods for identification of acrylonitrile-butadiene-styrene and high-impact polystyrene from waste computer equipment in Brazil, as well as their potential for mechanical recycling. The imprecise utilisation of symbols for identification of the polymers and the presence of additives containing toxic elements in determinate computer devices are some of the difficulties found for recycling of acrylonitrile-butadiene-styrene and high-impact polystyrene from waste computer equipment. However, the considerable performance of mechanical properties of the recycled acrylonitrile-butadiene-styrene and high-impact polystyrene when compared with the virgin materials confirms the potential for mechanical recycling of these polymers. © The Author(s) 2015.

  17. Chronic toxicity and three-generation reproduction study of styrene monomer in the drinking water of rats

    Energy Technology Data Exchange (ETDEWEB)

    Beliles, R.P.; Butala, J.H.; Stack, C.R.; Makris, S.

    1985-10-01

    Chronic toxicity and reproductive performance were evaluated in groups of rats receiving styrene monomer in their drinking water at nominal concentrations of 0, 125, or 250 ppm. Fifty male and 70 female rats in each test group and 76 males and 104 females in the control group were placed on a 2-year study and followed for observations of general health which included measurement of body weight, food and water consumption, hemograms, clinical chemistries, urinalysis, and histopathological examination. Ten males and 20 females from each group in the study were mated to produce F1 pups. These pups were subsequently mated to produce three generations of offspring, all maintained on styrene-treated drinking water. For each generation, the following were evaluated: fertility, litter size, pup viability, pup survival, sex ratio, pup body weight, weanling liver and kidney weight, and marrow cytogenetics. Except for a statistically significant reduction in water consumption for styrene-treated rats, no treatment-related changes, including mortality patterns, were reported for animals in the chronic study. The data evaluated for reproductive performance also showed no evidence of styrene-related changes. It was concluded that the administration of styrene in the drinking water of rats for 2 years produced no deleterious dose-related effects or decrements in reproductive performance.

  18. Mechanism of isotactic styrene polymerization with a C 6F 5-substituted bis(phenoxyimine) titanium system

    KAUST Repository

    Caporaso, Lucia

    2012-11-13

    We report a combined, experimental and theoretical, study of styrene polymerization to clarify the regio- and stereocontrol mechanism operating with a C 6F 5-substituted bis(phenoxyimine) titanium dichloride complex. Styrene homopolymerization, styrene-propene and styrene-ethene-propene copolymerizations have been carried out to this aim. A combination of 13C NMR analysis of the chain-end groups and of the microstructure of the homopolymers and copolymers reveals that styrene polymerization is highly regioselective and occurs prevalently through 2,1-monomer insertion. DFT calculations evidenced that steric interaction between the growing chain and the monomer in the transition state insertion stage is at the origin of this selectivity. The formation of isotactic polystyrene with a chain-end like microstructure is rationalized on the base of a mechanism similar to that proposed for the syndiospecific propene polymerization catalyzed by bis(phenoxyimine) titanium dichloride complexes. Finally, a general stereocontrol mechanism operative in olefin polymerization with this class of complexes is proposed. © 2012 American Chemical Society.

  19. Bioavailability of calcium of fresh cheeses, enteral food and mineral water. A study with stable calcium isotopes in young adult women

    NARCIS (Netherlands)

    Dokkum, W. van; Guéronnière, V. dela; Schaafsma, G.; Bouley, C.; Luten, J.; Latgé, C.

    1996-01-01

    True fractional Ca absorption from six foods was measured in twelve normal healthy women, aged 20-29 years. The tested foods were commercially available fresh cheese, fresh cheese prepared by new technology and rich in Ca, similar cheese with added Fe, enteral food, mineral water alone and combined

  20. Evaluation of Parasitic Pollution in Fresh Unwashed Herbs Sold in Izeh City, Iran

    Directory of Open Access Journals (Sweden)

    Valipour Nouroozi

    2015-11-01

    Full Text Available Background Fresh herbs are a crucial part of a good diet. However, they can easily become contaminated with food-borne pathogens. Eating fresh unwashed or improperly washed herbs has a major role in transmission of some important parasitic diseases. Objectives This study was carried out to evaluate parasitic pollution in fresh unwashed herbs sold in Izeh city, Iran. Materials and Methods Four hundred samples of fresh unwashed herbs were purchased from a distributor in Izeh city during January 2014 to April 2015. Detergent solution was added to 240 g of each sample. The mixture was shaken and washed solution was filtered through 0.2 µm bottle-top filter. The filtrate was discarded and filter was placed in a 50 mL conical screw cap tube. Then, the detergent solution was added. Following vortex, filter was discarded. The sediment was examined by light microscope after centrifuge. Finally, data descriptive analyses were carried out. Results Parasitic pollution was detected in 3.5% of the examined samples, including Cryptosporidium spp. oocyst (1.5%, Giardia spp. cyst (1%, Blastocystis spp. cyst (0.5% and Taenia spp. egg (0.5%. Conclusions Parasitic contamination of fresh herbs sold in Izeh may pose a health risk to consumers if eaten as unwashed or improperly washed.

  1. Thermotropic properties of phosphatidylcholine nanodiscs bounded by styrene-maleic acid copolymers.

    Science.gov (United States)

    Dominguez Pardo, J J; Dörr, J M; Renne, M F; Ould-Braham, T; Koorengevel, M C; van Steenbergen, M J; Killian, J A

    2017-11-01

    Styrene-maleic acid copolymers (SMA) have been gaining interest in the field of membrane research due to their ability to solubilize membranes into nanodics. The SMA molecules act as an amphipathic belt that surrounds the nanodiscs, whereby the hydrophobic styrene moieties can insert in between the lipid acyl chains. Here we used SMA variants with different styrene-to-maleic acid ratio (i.e. 2:1, 3:1 and 4:1) to investigate how lipid packing in the nanodiscs is affected by the presence of the polymers and how it depends on polymer composition. This was done by analyzing the thermotropic properties of a series of saturated phosphatidylcholines in nanodiscs using laurdan fluorescence and differential scanning calorimetry. In all cases it was found that the temperature of the main phase transition (Tm) of the lipids in the nanodiscs is downshifted and that its cooperativity is strongly reduced as compared to the situation in vesicles. These effects were least pronounced for lipids in nanodiscs bounded by SMA 2:1. Unexpected trends were observed for the calorimetric enthalpy of the transition, suggesting that the polymer itself contributes, possibly by rearranging around the nanodiscs when the lipids adopt the fluid phase. Finally, distinct differences in morphology were observed for nanodiscs at relatively high polymer concentrations, depending on the SMA variant used. Overall, the results suggest that the extent of preservation of native thermodynamic properties of the lipids as well as the stability of the nanodiscs at high polymer concentrations is better for SMA 2:1 than for the other SMA variants. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  2. Copolymerization of Carbon–carbon Double-bond Monomer (Styrene with Cyclic Monomer (Tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Sari Fouad

    2012-12-01

    Full Text Available We reported in this work that the cationic copolymerization in one step takes place between carbon–carbon double-bond monomer styrene with cyclic monomer tetrahydrofuran. The comonomers studied belong to different families: vinylic and cyclic ether. The reaction is initiated with maghnite-H+ an acid exchanged montmorillonite as acid solid ecocatalyst. Maghnite-H+ is already used as catalyst for polymerization of many vinylic and heterocyclic monomers. The oxonium ion of tetrahydrofuran and carbonium ion of styrene propagated the reaction of copolymerization. The acetic anhydride is essential for the maintenance of the ring opening of tetrahydrofuran and the entry in copolymerization. The temperature was kept constant at 40°C in oil bath heating for 6 hours. A typical reaction product was analyzed by 1H-NMR, 13C-NMR and IR and the formation of the copolymer was confirmed. The reaction was proved by matched with analysis. The maghnite-H+ allowed us to obtain extremely pure copolymer in good yield by following a simples operational conditions. Copyright © 2012 by BCREC UNDIP. All rights reservedReceived: 29th October 2012; Revised: 29th November 2012; Accepted: 29th November 2012[How to Cite: S. Fouad, M.I. Ferrahi, M. Belbachir. (2012. Copolymerization of Carbon–carbon Double-bond Monomer (Styrene with Cyclic Monomer (Tetrahydrofuran. Bulletin of Chemical Reaction Engineering & Catalysis, 7(2: 165-171. (doi:10.9767/bcrec.7.2.4074.165-171][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.2.4074.165-171 ] | View in 

  3. Modelling global fresh surface water temperature

    NARCIS (Netherlands)

    Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.

    2011-01-01

    Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment

  4. Nitrogen uptake kinetics of freshly isolated zooxanthellae

    Digital Repository Service at National Institute of Oceanography (India)

    Wafar, M.V.M.; Wafar, S.; Rajkumar, R.

    Zooxanthellae freshly isolated from the coral host Pocillopora damicornis exhibited substrate-saturable uptake kinetics for ammonium, nitrate and urea. Maximum uptake velocity for ammonium [10.1 nmol. ( mu chl-a)./1h/1] was greater than...

  5. FRESH VERSUS PROCESSED UTILIZATION OF FLORIDA GRAPEFRUIT

    OpenAIRE

    Brown, Mark G.; Spreen, Thomas H.; Muraro, Ronald P.

    1999-01-01

    The allocation problem of sending grapefruit to packinghouses versus processing plants is considered in this paper. The authors examine on-tree grower prices reported by the USDA for fresh and processed grapefruit and report that these prices do not reflect the alternative returns necessary for this allocation decision. The USDA processed on-tree price is a weighted average of returns for fruit that is intended for processing and fruit that is not intended for processing while the USDA fresh ...

  6. Biochemical Basis of Fresh Ham Color Development

    OpenAIRE

    Stufft, Kristen Marie

    2015-01-01

    Commercial hams display variation in color uniformity across the cut surface, especially the semimembranosus (SM) muscle. This variation in fresh ham color, or two-toning, persists through further processing and contributes to production of a less desirable end product. In an attempt to understand the underlying source of this color variation, we evaluated the differences in muscle fiber-type composition and glycolytic metabolism in the SM muscle of fresh hams differing in color uniformity. F...

  7. Dimensional accuracy of Acrylonitrile Butadiene Styrene injection molded parts produced in a pilot produc

    DEFF Research Database (Denmark)

    Mischkot, Michael; Davoudinejad, Ali; Charalambis, Alessandro

    Injection molding inserts manufactured additively by vat photopolymerization have become a serious option for significantly faster and more economical prototyping and pilot production due to technological progress and advancements in photopolymer materials in the recent years. 10 000 parts...... of a geometry including micro-features have been injection-molded in Acrylonitrile Butadiene Styrene (ABS) with a single 20x20x2.5 mm^3 injection molding insert manufactured in a photopolymer composite material. This research investigates the dimensional accuracy of the injection molded parts as a function...

  8. Oxidative Nitration of Styrenes for the Recycling of Low-Concentrated Nitrogen Dioxide in Air.

    Science.gov (United States)

    Hofmann, Dagmar; de Salas, Cristina; Heinrich, Markus R

    2015-09-21

    The oxidative nitration of styrenes in ethyl acetate represents a metal-free, environmentally friendly, and sustainable technique to recover even low concentrations of NO2 in air. Favorable features are that the product mixture comprising nitroalcohols, nitroketones, and nitro nitrates simplifies at lower concentrations of NO2 . Experiments in a miniplant-type 10 L wet scrubber demonstrated that the recycling technique is well applicable on larger scales at which initial NO2 concentrations of >10 000 ppm were reliably reduced to less than 40 ppm. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Star polymers by ATRP of styrene and acrylates employing multifunctional initiators

    DEFF Research Database (Denmark)

    Jankova, Katja Atanassova; Bednarek, Melania; Hvilsted, Søren

    2005-01-01

    Multifunctional initiators for atom transfer radical polymerization (ATRP) are prepared by converting ditrimethylolpropane with four hydroxyl groups, dipentaerythritol with six hydroxyl groups, and poly(3-ethyl-3-hydroxymethyl-oxetane) with similar to 11 hydroxyl groups to the corresponding 2......-bromoisobutyrates or 2-bromopropionates as obtained by reaction with acid bromides. Star polystyrene (PS) is produced by using these macroinitiators and neat styrene in a controlled manner by ATRP at 110 degrees C, employing the catalytic system CuBr and bipyridine. M. up to 51,000 associated with narrow molecular...

  10. Biodegradation of airborne acetone/styrene mixtures in a bubble column reactor.

    Science.gov (United States)

    Vanek, T; Silva, A; Halecky, M; Paca, J; Ruzickova, I; Kozliak, E; Jones, K

    2017-07-29

    The ability of a bubble column reactor (BCR) to biodegrade a mixture of styrene and acetone vapors was evaluated to determine the factors limiting the process efficiency, with a particular emphasis on the presence of degradation intermediates and oxygen levels. The results obtained under varied loadings and ratios were matched with the dissolved oxygen levels and kinetics of oxygen mass transfer, which was assessed by determination of k L a coefficients. A 1.5-L laboratory-scale BCR was operated under a constant air flow of 1.0 L.min -1 , using a defined mixed microbial population as a biocatalyst. Maximum values of elimination capacities/maximum overall specific degradation rates of 75.5 gC.m -3 .h -1 /0.197 gC.gdw -1 .h -1 , 66.0 gC.m -3 .h -1 /0.059 gC.gdw -1 .h -1 , and 45.8 gC.m -3 .h -1 /0.027 gC.gdw -1 .h -1 were observed for styrene/acetone 2:1, styrene-rich and acetone-rich mixtures, respectively, indicating significant substrate interactions and rate limitation by biological factors. The BCR removed both acetone and styrene near-quantitatively up to a relatively high organic load of 50 g.m -3 .h -1 . From this point, the removal efficiencies declined under increasing loading rates, accompanied by a significant drop in the dissolved oxygen concentration, showing a process transition to oxygen-limited conditions. However, the relatively efficient pollutant removal from air continued, due to significant oxygen mass transfer, up to a threshold loading rate when the accumulation of acetone and degradation intermediates in the aqueous medium became significant. These observations demonstrate that oxygen availability is the limiting factor for efficient pollutant degradation and that accumulation of intermediates may serve as an indicator of oxygen limitation. Microbial (activated sludge) analyses revealed the presence of amoebae and active nematodes that were not affected by variations in operational conditions.

  11. Reactivity and Regioselectivity in the Heck Reaction - A Hammett Study of 4-Substituted Styrenes

    DEFF Research Database (Denmark)

    Fristrup, Peter; Le Quement, Sebastian; Tanner, David Ackland

    2004-01-01

    The regioselectivity in the cationic Heck reaction of 4-substituted styrenes was addressed by a Hammett study. In this branching reaction, plots based on the substrate reactivity did not give meaningful data, whereas the product distribution was variable due to differing preferences for further...... substitution under the reaction conditions and, thus, unsuitable for Hammett plots. Mechanistically meaningful graphs were obtained by combination of the measured initial branching ratio with the approximately constant substrate reactivity. For the alpha-substitution a clear Hammett relation is observed...

  12. Metabolic activation and mutagenicity of 4 vinylic monomers (vinyl chloride, styrene, acrylonitrile, butadiene).

    Science.gov (United States)

    Duverger, M; Lambotte, M; Malvoisin, E; de Meester, C; Poncelet, F; Mercier, M

    1981-05-01

    The mutagenic activity and the metabolism of four vinylic monomers; vinyl chloride, styrene, acrylonitrile and butadiene are reviewed. Those chemicals are converted by the mixed function oxidases system of the endoplasmic reticulum into reactive intermediates which can interact with macromolecules within the cell. In order to examine the mutagenic activity of these compounds and their metabolites, different mutagenicity testing systems have been used: tests with S. typhimurium, E. coli, Schizosaccharomyces pombe, Saccharomyces cerevisiae, V79 Chinese Hamster cells, CHO cells, Drosophila melanogaster as well as evaluations of chromosome aberrations.

  13. High Solid Contents Copoly (Styrene/Butyl Acrylate-Cloisite 30B Nanocomposites

    Directory of Open Access Journals (Sweden)

    M. Mirzataheri

    2013-03-01

    Full Text Available Higher solid contents (20 % and 40 % nanocomposites of poly (styrene-co-butyl acrylate including higher content of Cloisite 30B (7 wt% and 10 wt % were prepared via miniemulsion polymerization. Stability of the final latexes proved outstanding combination of polymerization procedure and surfactants. Morphological studies revealed by TEM, SAX and XRD showed three structures of core-shell, armored and individual dispersion of clay layers within the polymer particles. The effect of Cloisite 30B content on the barrier properties presents excellent and wide use of these films for packaging and nanocoatings industries.

  14. TLC separation of hippuric, mandelic, and phenylglyoxylic acids from urine after mixed exposure to toluene and styrene

    Energy Technology Data Exchange (ETDEWEB)

    Bieniek, G.; Palys, E.; Wilczok, T.

    1982-05-01

    A method using thin-layer chromatography is described to determine the concentration of hippuric acid, mandelic acid, and phenylglyoxylic acid present in the urine after occupational mixed exposure to toluene and styrene. These substances are known metabolites of toluene and styrene, and therefore the evaluation to mixed exposure to toluene and styrene may be carried out separating these metabolites beforehand. Procedures are proposed to separate the metabolites as follows: separation of hippuric acid from mandelic acid, separation of mandelic acid from phenylglyoxylic acid, and separation of hippuric acid and mandelic acid from phenylglyoxylic acid. The developing reagent p-dimethylaminobenzaldehyde in acetic acid anhydride was used after separation on Kieselgel and Silicagel. The sensitivity of the method was 6 microgram of hippuric acid, 10 microgram of mandelic acid, and 7 microgram of phenylglyoxylic acid with an average recovery of 94.

  15. Molecular analysis on the utilization of oil palm empty fruit bunches fiber as reinforcement for acrylonitrile butadiene styrene biocomposites

    Science.gov (United States)

    Hermawan, B.; Nikmatin, S.; Alatas, H.; Sudaryanto; Sukaryo, S. G.

    2017-05-01

    Oil palm empty fruit bunches (OPEFB) was one of the solid waste produced by the palm oil factory and were totally plentiful in biomass. OPEFB fiber used as reinforcement of polymer matrix acrylonitrile butadiene styrene (ABS). The use of FTIR is to see that there is no changes in the molecules of the constituent biocomposite ABS and OPEFB. The reactivity of butadiene and styrene through the double bond- π conjugated system, contributed to the bond reaction with the maleic acid as compatibilizer witch is grafted to the system. It is concluded that the posible grafting reaction occurs by the addition of the MAH to the double bond of the butadiene and styrene. The hydroxyl group of cellulose can interact with this maleic acid to form a bond through the carboxyl group.

  16. Value-Added Exchange Rates

    OpenAIRE

    Rudolfs Bems; Robert C. Johnson

    2012-01-01

    This paper updates the conceptual foundations for measuring real effective exchange rates (REERs) to allow for vertical specialization in trade. We derive a value-added REER describing how demand for the value added that a country produces changes as the price of its value added changes relative to competitors. We then compute this index for 42 countries from 1970-2009 using trade measured in value added terms and GDP deflators. There are substantial differences between value-added and conven...

  17. Highly selective Wacker reaction of styrene derivatives: a green and efficient aerobic oxidative process promoted by benzoquinone/NaNO2/HClO4 under mild conditions.

    Science.gov (United States)

    Zhang, Guofu; Xie, Xiaoqiang; Wang, Yong; Wen, Xin; Zhao, Yun; Ding, Chengrong

    2013-05-14

    A green and efficient catalytic redox system for the aerobic oxidative Wacker oxidation of styrene derivatives at room temperature using molecular oxygen as the terminal oxidant without copper chloride has been developed. The newly developed system exhibited excellent catalytic activity for the smooth transformation of terminal styrene derivatives to the desired methyl ketones with up to 96% yield and >99% selectivity.

  18. Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Hong-Chuan Yang

    2007-01-01

    Full Text Available We study the energy-efficient configuration of multihop paths with automatic repeat request (ARQ mechanism in wireless ad hoc networks. We adopt a cross-layer design approach and take both the quality of each radio hop and the battery capacity of each transmitting node into consideration. Under certain constraints on the maximum tolerable transmission delay and the required packet delivery ratio, we solve optimization problems to jointly schedule the transmitting power of each transmitting node and the retransmission limit over each hop. Numerical results demonstrate that the path configuration methods can either significantly reduce the average energy consumption per packet delivery or considerably extend the average lifetime of the multihop route.

  19. Potentials for export of fresh raspberries from Serbia to EU fresh markets

    Directory of Open Access Journals (Sweden)

    Nikolić Ivan

    2012-12-01

    Full Text Available The aim of this paper is to present potentials of the most significant EU national markets for imports of fresh raspberries from Serbia. We carried out analysis of three markets with highest trade deficit of fresh raspberries expressed in quantities: Germany, Netherlands and Austria. The paper further analyses production and foreign trade trends in selected countries. According to results of this analysis, we identified monthly periods with highest potential for exports of fresh raspberries from Serbia to target markets. The paper also analyses wholesale prices of fresh raspberries and EU policy of direct support to raspberry producers.

  20. Monitoring of phytochemicals in fresh and fresh-cut vegetables: a comparison.

    Science.gov (United States)

    Alarcón-Flores, María Isabel; Romero-González, Roberto; Martínez Vidal, José Luis; Egea González, Francisco Javier; Garrido Frenich, Antonia

    2014-01-01

    Bearing in mind that fresh-cut market is currently the fastest growing subsector in the food industry, a comparison of the levels of phytochemicals in fresh and fresh-cut vegetables has been carried out. Thus, several families of phytochemicals, such as phenolic acids, isoflavones, flavones, flavonols and glucosinolates were determined in fresh and fresh-cut samples including tomato, carrot, grape, eggplant and broccoli. Both type of products have potential and similar beneficial properties, regarding its content as phytochemicals, except tomato, which should be consumed as fresh. Other factors such as commercial presentation (sliced, grated, diced) and storage conditions (temperature and light) were evaluated observing that in eggplant, the content of phenolic acids is statistically different depending on the presentation. On the other hand, the content of phytochemicals was higher when fresh-cut carrots were stored at 4°C regardless of the presence or absence of light. Multivariate analysis, based on cluster analysis was used as a first approach to distinguish between fresh and fresh-cut samples, obtaining good results except for eggplant and carrot. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Effect of rutile titania dioxide nanoparticles on the mechanical property, thermal stability, weathering resistance and antibacterial property of styrene acrylic polyurethane coating

    Science.gov (United States)

    Vuong Nguyen, Thien; Nguyen, Tuan Anh; Dao, Phi Hung; Phuc Mac, Van; Hiep Nguyen, Anh; Thanh Do, Minh; Nguyen, The Huu

    2016-12-01

    This study aims to enhance the mechanical properties, thermal stability, weathering resistance and antibacterial property of a styrene acrylic polyurethane coating by adding rutile titania dioxide (R-TiO2) nanoparticles in coating formulation. The styrene acrylic polyurethane/R-TiO2 nanocomposite had been prepared by using ultrasonication. The effects of nanoparticles on the mechanical properties, thermal stability and weathering resistance of as-prepared coatings were investigated by using the adhesion strength and ball impact tests, the Fourier transform infrared and UV-vis analyses, thermogravimetric analysis (TGA), and UV/condensation weathering chamber equipped with UVA-340 fluorescent lamps, respectively. The disperse quality of nanoparticles in the coating was examined by using the field emission scanning electron microscope (FESEM). The mechanical test results showed that suitable content of R-TiO2 nanoparticles in the nanocomposite coating was 2 wt%. The FESEM images indicated that the nanoparticles were dispersed homogeneously into the entire volume of the coating. For the nanocomposite prepared by 3 h of ultrasonication, the average size of nanoparticles was in range of 40-50 nm. The ball impact and adhesion tests showed that the incorporation of nanoparticles into the coating significantly enhanced the impact strength from 120 to 145 kg cm and increased the adhesion from level 1 to level 0. The TGA test illustrated that in presence of nanoparticles, the decomposition temperature of coating increased from 146.9 °C to 154.21 °C. For the temperature at 50% loss in mass (T 50%), it was found that the T 50% of the neat coating is 351.86 °C. Adding the 2 wt% R-TiO2 nanoparticles into coating increased the T 50% value to 360.06 °C. After UV/condensation accelerated weathering test (30 cycles), the significant improvement in weight loss, impact strength and adhesion of the neat coating was observed with the presence of nanoparticles. The antibacterial test

  2. Establishing the Global Fresh Water Sensor Web

    Science.gov (United States)

    Hildebrand, Peter H.

    2005-01-01

    This paper presents an approach to measuring the major components of the water cycle from space using the concept of a sensor-web of satellites that are linked to a data assimilation system. This topic is of increasing importance, due to the need for fresh water to support the growing human population, coupled with climate variability and change. The net effect is that water is an increasingly valuable commodity. The distribution of fresh water is highly uneven over the Earth, with both strong latitudinal distributions due to the atmospheric general circulation, and even larger variability due to landforms and the interaction of land with global weather systems. The annual global fresh water budget is largely a balance between evaporation, atmospheric transport, precipitation and runoff. Although the available volume of fresh water on land is small, the short residence time of water in these fresh water reservoirs causes the flux of fresh water - through evaporation, atmospheric transport, precipitation and runoff - to be large. With a total atmospheric water store of approx. 13 x 10(exp 12)cu m, and an annual flux of approx. 460 x 10(exp 12)cu m/y, the mean atmospheric residence time of water is approx. 10 days. River residence times are similar, biological are approx. 1 week, soil moisture is approx. 2 months, and lakes and aquifers are highly variable, extending from weeks to years. The hypothesized potential for redistribution and acceleration of the global hydrological cycle is therefore of concern. This hypothesized speed-up - thought to be associated with global warming - adds to the pressure placed upon water resources by the burgeoning human population, the variability of weather and climate, and concerns about anthropogenic impacts on global fresh water availability.

  3. Acceptance and storage of fresh cheese made with essential oils

    Directory of Open Access Journals (Sweden)

    Joelmir Grassi Presente

    2017-08-01

    Full Text Available The aim of this work was to evaluate the acceptance and conservation of Minas fresh cheese with essential oils added of oregano and ginger in its formulation. The quality of the milk used as raw material was evaluated for pH, acidity, alizarol, total solids, density, and total microbial load. The cheeses produced were characterized as pH, acidity, moisture, lipids, proteins and ashes. The cheeses were also evaluated by sensorial affective tests using hedonic and attitude scales, in order to determine the acceptance and purchase intention by judges. The count of total aerobic mesophilic microorganisms was used to estimate the shelf-life of cheeses. The milk used as raw material is presented within the quality standards required by legislation. The cheeses made with essential oils showed pH and acidity around 6.9 and 0.87%, respectively, 57.6% moisture, 31.3% lipids, 11.4% protein and 0.9% ash. The cheese added essential oil of oregano and the control cheese were those given by the judges the best values for acceptance (7.5 and 7.6, respectively and purchase intention (4.2 and 4.4 respectively. Regarding the estimated shelf-life, the cheeses added essential oil of oregano and ginger had lower overall microbial load values compared to the control (no oil and mixed (two oils addition, presented counts values with up 106 UFC/g only from the 28th day of storage.

  4. Investigation on physical behavior of styrene wood-polymer in different concentrations of monomer

    Directory of Open Access Journals (Sweden)

    maryam ghorbani

    2016-09-01

    Full Text Available This research was conducted to study the effect of different concentrations of styrene lumen monomer on the physical properties of beech wood. Physical test samples were prepared according to ASTM-D1037 standard and treated with vacuum-pressure method at five concentration levels; 0, 40, 60, 80 and 100 percent of soluble monomer. For polymerization, treated samples were heated in oven for two 24-hour period at 90 and 103ºC respectively. Monomer and polymer absorption, density variation, water absorption, swelling and anti-swelling efficiency (ASE were determined. According to the results, Monomer and polymer absorption were increment by monomer concentration increase, and they were reported 38.2% and 26% in highest level. With polymer absorption enhancement, density of wood increased from 0/63g/cm³ in control to 0/91g/cm³ in the highest monomer concentration level that reduces pores in wood-polymer structure. Absorbed polymer enhancement decreased hydrophilicity and dimensional changes of treated samples, so that water absorption and swelling volume of the samples saturated with 100% concentration of monomer were decreased 64% and 45.3% after the longest immersion time. Highest Anti-swelling efficiency of Styrene-saturated samples was determined 56.15% in the maximum concentration level of treatment.

  5. GPCR-styrene maleic acid lipid particles (GPCR-SMALPs): their nature and potential.

    Science.gov (United States)

    Wheatley, Mark; Charlton, Jack; Jamshad, Mohammed; Routledge, Sarah J; Bailey, Sian; La-Borde, Penelope J; Azam, Maria T; Logan, Richard T; Bill, Roslyn M; Dafforn, Tim R; Poyner, David R

    2016-04-15

    G-protein-coupled receptors (GPCRs) form the largest class of membrane proteins and are an important target for therapeutic drugs. These receptors are highly dynamic proteins sampling a range of conformational states in order to fulfil their complex signalling roles. In order to fully understand GPCR signalling mechanisms it is necessary to extract the receptor protein out of the plasma membrane. Historically this has universally required detergents which inadvertently strip away the annulus of lipid in close association with the receptor and disrupt lateral pressure exerted by the bilayer. Detergent-solubilized GPCRs are very unstable which presents a serious hurdle to characterization by biophysical methods. A range of strategies have been developed to ameliorate the detrimental effect of removing the receptor from the membrane including amphipols and reconstitution into nanodics stabilized by membrane scaffolding proteins (MSPs) but they all require exposure to detergent. Poly(styrene-co-maleic acid) (SMA) incorporates into membranes and spontaneously forms nanoscale poly(styrene-co-maleic acid) lipid particles (SMALPs), effectively acting like a 'molecular pastry cutter' to 'solubilize' GPCRs in the complete absence of detergent at any stage and with preservation of the native annular lipid throughout the process. GPCR-SMALPs have similar pharmacological properties to membrane-bound receptor, exhibit enhanced stability compared with detergent-solubilized receptors and being non-proteinaceous in nature, are fully compatible with downstream biophysical analysis of the encapsulated GPCR. © 2016 Authors; published by Portland Press Limited.

  6. Preliminary results on the fatigue life characterization of a styrenic dielectric elastomer (Conference Presentation)

    Science.gov (United States)

    Chen, Yi; Vertechy, Rocco; Fontana, Marco

    2017-04-01

    Recently, a styrenic rubber membrane (commercialized under the name of "THERABAND YELLOW 11726") demonstrated excellent electromechanical properties for the development of high power density and highly efficient dielectric elastomer transducers (DETs). In particular, in an experimental application as generator, an inflated circular diaphragm DET based on this material made it possible to consistently convert pneumatic energy into electricity at a maximum energy density per cycle and power density greater than 400 J/kg and 650 W/kg, respectively, with even higher numbers being expected for DETs configured so as to have the material working in uniform states of deformation. As for any other existing dielectric elastomer material, these experimented performances can however be sustained for a limited number of cycles only, after which the DET will fail irreversibly. To date, very little information is available on the fatigue life performances of dielectric elastomer materials and of the transducers made thereof. Having identified the electrical breakdown as the most probable mode of DET failure, this paper reports for the first time on a set of lifetime constant-electric-stress tests conducted on the considered styrenic dielectric elastomer membrane. Specifically, the paper starts with a description of the employed experimental set-up and procedures. Then, it summarizes the obtained experimental results. Finally, it concludes with a discussion on how the acquired data could be used in a design procedure to find optimal tradeoffs between DET performance and lifetime/reliability.

  7. Ag-Cu Bimetallic Nanoparticles Prepared by Microemulsion Method as Catalyst for Epoxidation of Styrene

    Directory of Open Access Journals (Sweden)

    Hong-Kui Wang

    2012-01-01

    Full Text Available Ag/Cu bimetallic nanocatalysts supported on reticulate-like γ-alumina were prepared by a microemulsion method using N2H4·H2O as the reducing agent. The catalysts were activated by calcination followed with hydrogen reduction at 873K, and the properties were confirmed using various characterization techniques. Compared with metal oxides particles, Ag-Cu particles exhibited smaller sizes (<5 nm after calcination in H2 at 873K. XPS results indicated that the binding energies changed with the Ag/Cu ratios, suggesting that increasing the copper content gave both metals a greater tendency to lose electrons. Furthermore, Ag-Cu bimetallic nanoparticles supported on γ-alumina showed better catalytic activity on the epoxidation of styrene as compared with the corresponding monometallic silver or copper. The styrene oxide selectivity could reach 76.6% at Ag/Cu molar ratio of 3/1, while the maximum conversion (up to 94.6% appeared at Ag/Cu molar ratio of 1/1 because of the maximum interaction between silver and copper.

  8. Confirmation of Monod Model for Biofiltration of Styrene Vapors from Waste Flue Gas

    Directory of Open Access Journals (Sweden)

    Reza Dehghanzadeh

    2012-12-01

    Full Text Available Background: The objective of this research was to investigate the kinetic behavior of the biofil-tration process for the removal of styrene.Methods: A three stage compost based biofilter was inoculated with thickened activated sludge. The reaction order rate constants were obtained from continuous experiments and used as the specific growth rate for the Monod equation.Results: The measured concentration profiles show a linear dependence on the bed height in the biofilter at higher loadings, such as 75 and 45 g m-3 h-1. This is the condition of reaction limitation for a reaction with zero-order kinetics. From the experimental data, maximum elimination capac-ity (ECmax was estimated to be 44, 40 and 26 g m-3 h-1 at empty bed retention times (EBRTs of 120, 60 and 30 s, respectively. However, at lower loadings, the measured concentration profile of the biofilter is one of exponential increase, which is the condition of both reaction and diffusion limitations for a reaction with zero-order kinetics. Maximum elimination capacities found from the experimental results were the same as Monod model predictions. Both the experimental re-sults and the model predictions showed the influence of EBRT on the removal rate of styrene, particularly for the highest loading rate.Conclusion: In terms of the practical applications of the proposed models have the advantage of being simpler than Monod kinetics and Monod kinetics requires a numerical solution.

  9. Structure of poly(styrene-b-ethylene-alt-propylene) diblock copolymer micelles in squalane.

    Science.gov (United States)

    Choi, Soo-Hyung; Bates, Frank S; Lodge, Timothy P

    2009-10-22

    The temperature dependence of the micellar structures formed by poly(styrene-b-ethylene-alt-propylene) (SEP) diblock copolymers in squalane, a highly selective solvent for the PEP blocks, has been studied using dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). Four SEP diblock copolymers were prepared by sequential anionic polymerization of styrene and isoprene, followed by hydrogenation of the isoprene blocks, to yield SEP(17-73), SEP(26-66), SEP(36-69), and SEP(42-60), where the numbers indicate block molecular weights in kDa. All four polymers formed well-defined spherical micelles. In dilute solution, DLS provided the temperature-dependent mean hydrodynamic radius, R(h), and its distribution, while detailed fitting of the SAXS profiles gave the core radius, R(c), the equivalent hard sphere radius, R(hs), and an estimate of the aggregation number, N(agg). In general, the micelles became smaller as the critical micelle temperature (CMT) was approached, which was well above the glass transition of the core block. As concentration increased the micelles packed onto body centered cubic lattices for all four copolymers, which underwent order-disorder transitions upon heating near the dilute solution CMTs. The results are discussed in terms of current understanding of block copolymer solution self-assembly, and particular attention is paid to the issue of equilibration, given the high glass transition temperature of the core block.

  10. Confirmation of monod model for biofiltration of styrene vapors from waste flue gas.

    Science.gov (United States)

    Dehghanzadeh, Reza; Roshani, Babak; Asadi, Mahzar; Fahiminia, Mohammad; Aslhashemi, Ahmad

    2012-01-01

    The objective of this research was to investigate the kinetic behavior of the biofil¬tration process for the removal of styrene. A three stage compost based biofilter was inoculated with thickened activated sludge. The reaction order rate constants were obtained from continuous experiments and used as the specific growth rate for the Monod equation. The measured concentration profiles show a linear dependence on the bed height in the biofilter at higher loadings, such as 75 and 45 g m-3 h-1. This is the condition of reaction limitation for a reaction with zero-order kinetics. From the experimental data, maximum elimination capac¬ity (ECmax) was estimated to be 44, 40 and 26 g m-3 h-1 at empty bed retention times (EBRTs) of 120, 60 and 30 s, respectively. However, at lower loadings, the measured concentration profile of the biofilter is one of exponential increase, which is the condition of both reaction and diffusion limitations for a reaction with zero-order kinetics. Maximum elimination capacities found from the experimental results were the same as Monod model predictions. Both the experimental re¬sults and the model predictions showed the influence of EBRT on the removal rate of styrene, particularly for the highest loading rate. In terms of the practical applications of the proposed models have the advantage of being simpler than Monod kinetics and Monod kinetics requires a numerical solution.

  11. Occupational exposures to styrene vapor in a manufacturing plant for fiber-reinforced composite wind turbine blades.

    Science.gov (United States)

    Hammond, Duane; Garcia, Alberto; Feng, H Amy

    2011-07-01

    A utility-scale wind turbine blade manufacturing plant requested assistance from the National Institute for Occupational Safety and Health (NIOSH) in controlling worker exposures to styrene at a plant that produced 37 and 42 m long fiber-reinforced wind turbine blades. The plant requested NIOSH assistance because previous air sampling conducted by the company indicated concerns about peak styrene concentrations when workers entered the confined space inside of the wind turbine blade. NIOSH researchers conducted two site visits and collected personal breathing zone and area air samples while workers performed the wind turbine blade manufacturing tasks of vacuum-assisted resin transfer molding (VARTM), gelcoating, glue wiping, and installing the safety platform. All samples were collected during the course of normal employee work activities and analyzed for styrene using NIOSH Method 1501. All sampling was task based since full-shift sampling from a prior Occupational Safety and Health Administration (OSHA) compliance inspection did not show any exposures to styrene above the OSHA permissible exposure limit. During the initial NIOSH site visit, 67 personal breathing zone and 18 area air samples were collected while workers performed tasks of VARTM, gelcoating, glue wipe, and installation of a safety platform. After the initial site visit, the company made changes to the glue wipe task that eliminated the need for workers to enter the confined space inside of the wind turbine blade. During the follow-up site visit, 12 personal breathing zone and 8 area air samples were collected from workers performing the modified glue wipe task. During the initial site visit, the geometric means of the personal breathing zone styrene air samples were 1.8 p.p.m. (n = 21) for workers performing the VARTM task, 68 p.p.m. (n = 5) for workers installing a safety platform, and 340 p.p.m. (n = 14) for workers performing the glue wipe task, where n is the number of workers sampled for a

  12. INNOVATIVE FRESH WATER PRODUCTION PROCESS FOR FOSSIL FUEL PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    James F. Klausner; Renwei Mei; Yi Li; Jessica Knight

    2004-09-01

    An innovative Diffusion Driven Desalination (DDD) process was recently described where evaporation of mineralized water is driven by diffusion within a packed bed. The energy source to drive the process is derived from low pressure condensing steam within the main condenser of a steam power generating plant. Since waste heat is used to drive the process, the main cost of fresh water production is attributed to the energy cost of pumping air and water through the packed bed. This report describes the annual progress made in the development and analysis of a Diffusion Driven Desalination (DDD) system. A combined thermodynamic and dynamic analysis demonstrates that the DDD process can yield a fresh water production of 1.03 million gallon/day by utilizing waste heat from a 100 MW steam power plant based on a condensing steam pressure of only 3'' Hg. Throughout the past year, the main focus of the desalination process has been on the diffusion tower and direct contact condenser. Detailed heat and mass transfer analyses required to size and analyze these heat and mass transfer devices are described. An experimental DDD facility has been fabricated, and temperature and humidity data have been collected over a range of flow and thermal conditions. The analyses agree quite well with the current data and the information available in the literature. Direct contact condensers with and without packing have been investigated. It has been experimentally observed that the fresh water production rate is significantly enhanced when packing is added to the direct contact condensers.

  13. Quality and Acceptability of Meat Nuggets with Fresh Gel

    Directory of Open Access Journals (Sweden)

    V. Rajkumar

    2016-05-01

    Full Text Available Aloe vera has been used worldwide for pharmaceutical, food, and cosmetic industries due to its wide biological activities. However, quality improvement of low fat meat products and their acceptability with added Aloe vera gel (AVG is scanty. The aim of this study was to explore the feasibility of using fresh AVG on physicochemical, textural, sensory and nutritive qualities of goat meat nuggets. The products were prepared with 0%, 2.5%, and 5% fresh AVG replacing goat meat and were analyzed for proximate composition, physicochemical and textural properties, fatty acid profile and sensory parameters. Changes in lipid oxidation and microbial growth of nuggets were also evaluated over 9 days of refrigerated storage. The results showed that AVG significantly (p<0.05 decreased the pH value and protein content of meat emulsion and nuggets. Product yield was affected at 5% level of gel. Addition of AVG in the formulation significantly affected the values of texture profile analysis. The AVG reduced the lipid oxidation and microbial growth in nuggets during storage. Sensory panelists preferred nuggets with 2.5% AVG over nuggets with 5% AVG. Therefore, AVG up to 2.5% level could be used for quality improvement in goat meat nuggets without affecting its sensorial, textural and nutritive values.

  14. Consumer's Fresh Produce Food Safety Practices: Outcomes of a Fresh Produce Safety Education Program

    Science.gov (United States)

    Scott, Amanda R.; Pope, Paul E.; Thompson, Britta M.

    2009-01-01

    The Centers for Disease Control and Prevention estimate that there are 76 million cases of foodborne disease annually. Foodborne disease is usually associated with beef, poultry, and seafood. However, there is an increasing number of foodborne disease cases related to fresh produce. Consumers may not associate fresh produce with foodborne disease…

  15. Decontamination of fresh and fresh-cut fruits and vegetables with cold plasma technology

    Science.gov (United States)

    Contamination of fresh and fresh-cut fruits and vegetables by foodborne pathogens has prompted research into novel interventions. Cold plasma is a nonthermal food processing technology which uses energetic, reactive gases to inactivate contaminating microbes. This flexible sanitizing method uses ele...

  16. Value Added in English Schools

    OpenAIRE

    Andrew Ray; Tanya McCormack; Helen Evans

    2009-01-01

    Value-added indicators are now a central part of school accountability in England, and value-added information is routinely used in school improvement at both the national and the local levels. This article describes the value-added models that are being used in the academic year 2007–8 by schools, parents, school inspectors, and other professionals in local and national governments. The article outlines the development of value-added models in England following the introduction of national t...

  17. SAGD processes with fresh water contact

    Energy Technology Data Exchange (ETDEWEB)

    Thimm, H.F. [Thimm Petroleum Technologies Inc. (Canada)

    2011-07-01

    In the Athabasca region, several bitumen reservoirs are shallow, located less than 400 meters below grade. These deposits are suitable for SAGD exploitation but the steam could come into contact with fresh water, which carries the risk of contaminating this resource. Operators are thus required by regulators to address this issue at the project application stage. The aim of this paper is to examine the potential effect of contact between fresh water and a bitumen bearing zone in a field in Northern Alberta. Investigations were conducted with a steam zone temperature of 200 degree Celsius and measurements were conducted at a plant close to the proposed project. Results showed that the accumulation of hydrogen sulphide would protect the water column and PAH, benzene and toluene were found to be potential concerns but they were not detected during implementation of a similar project. This paper demonstrated that the proposed project does not constitute a threat to fresh water.

  18. Microbiological Quality of Fresh Nopal Juice.

    Science.gov (United States)

    Hernández-Anguiano, Ana María; Landa-Salgado, Patricia; Eslava-Campos, Carlos Alberto; Vargas-Hernández, Mateo; Patel, Jitendra

    2016-12-10

    The consumption of fresh nopal cactus juice is widely popular among health-conscious consumers in Mexico. The juice is prepared from fresh cladodes that have only been rinsed with tap water and are not subjected to a pasteurization or terminal bacterial reduction process. The aim of this study was to evaluate the microbial quality of commercially available fresh juices (n = 162) made with nopal in Texcoco, State of Mexico, during the summer and spring season. Standard microbiological methods, the PCR technique and the serological method were used for isolation and identification of bacteria. All samples contained total coliforms and 91% were positive for Escherichia coli. Although total coliforms and E. coli were detected throughout the study, their populations were significantly lower (p nopal juices is unacceptable due to its health significance. The information generated in this study is relevant for human health risk assessment associated with the consumption of unpasteurized nopal juices and potential interventions to minimize pathogen contamination.

  19. Value Added in English Schools

    Science.gov (United States)

    Ray, Andrew; McCormack, Tanya; Evans, Helen

    2009-01-01

    Value-added indicators are now a central part of school accountability in England, and value-added information is routinely used in school improvement at both the national and the local levels. This article describes the value-added models that are being used in the academic year 2007-8 by schools, parents, school inspectors, and other…

  20. Fracture morphologies of carbon-black-loaded SBR (styrene-butadiene rubber) subjected to low-cycle, high-stress fatigue. [Styrene-butadiene rubber

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, A.; Lesuer, D.R.; Patt, J.

    1988-02-01

    Experimental results, together with an analytical model, related to the loss in tensile strength of styrene-butadiene rubber (SBR) loaded with carbon black (CB) that had been subjected to low-cycle, high-stress fatigue tests were presented in a prior paper. The drop in tensile strength relative to that of a virgin sample was considered to be a measure of damage induced during the fatigue test. The present paper is a continuation of this study dealing with the morphological interpretations of the fractured surfaces, whereby the cyclic-tearing behavior, resulting in the damage, is related to the test and material parameters. It was found that failure is almost always initiated in the bulk of a sample at a material flaw. The size and definition of a flaw increase with an increase in carbon-black loading. Initiation flaw sites are enveloped by fan-shaped or penny-shaped regions which develop during cycling. The size and morphology of a fatigue-tear region appears to be independent of the fatigue load or the extent of the damage (strength loss). By contrast, either an increase in cycling load or an increase in damage at constant load increases the definition of the fatigue-region morphology for all formulations of carbon-black. On the finest scale, the morphology can be described in terms of tearing of individual groups of rubber strands, collapsing to form a cell-like structure. 18 refs., 13 figs.

  1. Matrix-assisted laser desorption/ionization sample preparation optimization for structural characterization of poly(styrene-co-pentafluorostyrene) copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Tisdale, Evgenia; Kennedy, Devin; Wilkins, Charles, E-mail: cwilkins@uark.edu

    2014-01-15

    Graphical abstract: -- Highlights: •We optimized sample preparation for MALDI TOF poly(styrene-copentafluorostyrene) co-polymers. •Influence of matrix choice was investigated. •Influence of matrix/analyte ratio was examined. •Influence of analyte/salt ratio (for Ag+ salt) was studied. -- Abstract: The influence of the sample preparation parameters (the choice of the matrix, matrix:analyte ratio, salt:analyte ratio) was investigated and optimal conditions were established for the MALDI time-of-flight mass spectrometry analysis of the poly(styrene-co-pentafluorostyrene) copolymers. These were synthesized by atom transfer radical polymerization. Use of 2,5-dihydroxybenzoic acid as matrix resulted in spectra with consistently high ion yields for all matrix:analyte:salt ratios tested. The optimized MALDI procedure was successfully applied to the characterization of three copolymers obtained by varying the conditions of polymerization reaction. It was possible to establish the nature of the end groups, calculate molecular weight distributions, and determine the individual length distributions for styrene and pentafluorostyrene monomers, contained in the resulting copolymers. Based on the data obtained, it was concluded that individual styrene chain length distributions are more sensitive to the change in the composition of the catalyst (the addition of small amount of CuBr{sub 2}) than is the pentafluorostyrene component distribution.

  2. Determining the efficiency of ZSM-5 zeolite impregnated with nanoparticles of titanium dioxide in the photocatalytic removal of styrene vapors

    Directory of Open Access Journals (Sweden)

    Mojtaba Nakhaei pour

    2017-03-01

    Full Text Available Introduction: Styrene monomer is a volatile organic compound that has many applications particularly in plastic, rubber and paint industries. According to the harmful effects of these compounds on human and environment, reducing and controling of them seem necessary. Therefore, in this study removal of styrene was investigated using photocatalytic process of titanium dioxide nanoparticles stabilized on ZSM-5. Methods: After stabilization of titanium dioxide nanoparticles on ZSM-5 zeolite, BET, SEM and XRD analysis were used to determine the characteristics of nanoparticles. Experiments were conducted at ambient temperature in laboratory scale. Concentration of produced styrene in the experiments was 50 and 300 ppm, and input flow rate was 1 l/min. Results: images and spectra obtained through XRD and SEM-EDAX showed that  nano-catalysts are well- stabilized. The results showed that by increasing of input concentration of styrene from 50 to 300 ppm, photocatalytic removal efficiency are reduced. Also, adsorption capacity of the catalyst bed in concentrations of 50 and 300 ppm was calculated 16.3 and19.4 mg/gr of adsorbent respectively. Conclusion: The results show that the use of hybrid bed can increase the removal efficiency of contaminants. And due to low cost of application of these systems compared to conventional methods, it is recommended that more comprehensive studies to be done regarding the optimization of the parameters affecting the process of photocatalytic removal.

  3. Stepwise Swelling of a Thin Film of Lamellae-Forming Poly(styrene-b-butadiene) in Cyclohexane Vapor

    DEFF Research Database (Denmark)

    Di, Zhenyu; Posselt, Dorthe; Smilgies, Detlef-M.

    2012-01-01

    We investigated the swelling of a thin film of lamellae-forming poly(styrene-b-butadiene) in cyclohexane vapor. The vapor pressure and thus the degree of swelling of the film are increased in a stepwise manner using a custom-built sample cell. The resulting structural changes during and after eac...

  4. N-Heterocyclic carbene-palladium(II)-1-methylimidazole complex catalyzed Mizoroki-Heck reaction of aryl chlorides with styrenes

    National Research Council Canada - National Science Library

    Gao, Ting-Ting; Jin, Ai-Ping; Shao, Li-Xiong

    2012-01-01

    A well-defined N-heterocyclic carbene-palladium(II)-1-methylimidazole [NHC-Pd(II)-Im] complex 1 was found to be an effective catalyst for the Mizoroki-Heck reaction of a variety of aryl chlorides with styrenes...

  5. Solute recovery from ionic liquids: a conceptual design study for recovery of styrene monomer from [4-mebupy][BF4

    NARCIS (Netherlands)

    Jongmans, Mark; Trampe, J.; Schuur, Boelo; de Haan, A.B.

    2013-01-01

    Extractive distillation using ionic liquids (ILs) is a promising technology to separate the close-boiling mixture ethylbenzene/styrene. A proper solvent regeneration is crucial to obtain a technical and economic feasible process. In this work, several regeneration technologies were studied to

  6. Highly selective oxidation of styrene to benzaldehyde over a tailor-made cobalt oxide encapsulated zeolite catalyst.

    Science.gov (United States)

    Liu, Jiangyong; Wang, Zihao; Jian, Panming; Jian, Ruiqi

    2018-02-02

    A tailor-made catalyst with cobalt oxide particles encapsulated into ZSM-5 zeolites (Co 3 O 4 @HZSM-5) was prepared via a hydrothermal method with the conventional impregnated Co 3 O 4 /SiO 2 catalyst as the precursor and Si source. Various characterization results show that the Co 3 O 4 @HZSM-5 catalyst has well-organized structure with Co 3 O 4 particles compatibly encapsulated in the zeolite crystals. The Co 3 O 4 @HZSM-5 catalyst was employed as an efficient catalyst for the selective oxidation of styrene to benzaldehyde with hydrogen peroxide as a green and economic oxidant. The effect of various reaction conditions including reaction time, reaction temperature, different kinds of solvents, styrene/H 2 O 2 molar ratio and catalyst dosage on the catalytic performance were systematically investigated. Under the optimized reaction condition, the yield of benzaldehyde can achieve 78.9% with 96.8% styrene conversion and 81.5% benzaldehyde selectivity. Such an excellent catalytic performance can be attributed to the synergistic effect between the confined reaction environment and the proper acidic property. In addition, the reaction mechanism with Co 3 O 4 @HZSM-5 as the catalyst for the selective oxidation of styrene to benzaldehyde was reasonably proposed. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Disruption of the Electrical Conductivity of Highly Conductive Poly(3,4-ethylenedioxythiophene) : Poly(styrene sulfonate) by Hypochlorite

    NARCIS (Netherlands)

    Oostra, A. Jolt; Bos, Karel H.W. van den; Blom, Paul W.M.; Michels, Jasper J.

    2013-01-01

    The effect of hypochlorite treatment on the layer thickness and conductivity of a state-of-the-art high conducting poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is investigated as a function of exposure time and hypochlorite concentration. Because of overoxidation by the

  8. Entropic Separation of Styrene/Ethylbenzene Mixtures by Exploitation of Subtle Differences in Molecular Configurations in Ordered Crystalline Nanoporous Adsorbents

    NARCIS (Netherlands)

    Torres-Knoop, A.; Heinen, J.; Krishna, R.; Dubbeldam, D.

    2015-01-01

    The separation of styrene/ethylbenzene mixture is of great importance in the petrochemical industry. Current technology uses distillation; this separation is difficult because of the small, 9 K, difference in the boiling points. An alternative separation method uses selective adsorption in

  9. On the form of the strain energy function for a family of SBR materials. [Styrene-Butadiene Rubber

    Science.gov (United States)

    Arenz, R. J.

    1977-01-01

    Styrene-butadiene materials with varying crosslink densities are analyzed through use of a strain energy function of the type introduced by Valanis and Landel (1967). A form of the strain energy function derived from strip biaxial tests proves to be accurate when checked against uniaxial and other biaxial test results.

  10. Reactive blending of poly(styrene-maleic) anhydride with poly(phenylene oxide) by addition of `-amino-polystyrene

    NARCIS (Netherlands)

    Koning, Cor; Ikker, Andreas; Ikker, A.; Borggreve, Rein; Leemans, Luc; Möller, Martin; Moller, M.

    1993-01-01

    -(3-Aminopropyl-l-amino)polystyrene (-amino-PS) was melt-blended with styrene/maleic anhydride copolymers (SMA) containing 28 wt% maleic anhydride groups. The terminal primary amino group can react with the maleic anhydride monomer units in SMA, forming imides. The resulting product turned out to be

  11. Modelling the steady state and dynamic conditions of a biotrickling filter treating styrene and acetone in air

    Directory of Open Access Journals (Sweden)

    Andrew Mark Gerrard

    2010-10-01

    Full Text Available The aim of this work was the study a trickling biofilter, where water was circulated throughout the bed. In the first steady state experiment, the packing materials used were 25mm Pall rings. The airflow rate was increased gradually and the concentration of styrene in the air stream was held constant. In the second experiment, 15mm Pall rings were used. In this case, the feed contained both styrene and a small amount of acetone. The concentration of acetone and the air flow rate were kept constant, but the styrene inlet concentration was increased. The concentrations were measured at the input, and also at an intermediate and the outlet position in the biotrickling filter to determine the concentration profile along the reactor. Using the values of coefficient of determination (R² and the coefficient of variation of the fitted constant as criteria, a zero order model with diffusional limitation was chosen as the best representation of the data. Then a further, third, set of experiments were done at unsteady state, using step changes of the inlet concentration levels of both styrene and acetone at a steady air flow-rate . Inlet and outlet concentrations were measured as a function of time and the results were adequately described using a simple first order model.

  12. EVALUATION OF POLLUTION PREVENTION OPTIONS TO REDUCE STYRENE EMISSIONS FROM FIBER-REINFORCED PLASTIC OPEN MOLDING PROCESSES

    Science.gov (United States)

    Pollution prevention (P2) options to reduce styrene emissions, such as new materials, and application equipment, are commercially available to the operators of open molding processes. However, information is lacking on the emissions reduction that these options can achieve. To me...

  13. Recent Advances in Rare Earth Complexes Bearing Allyl Ligands and Their Reactivity towards Conjugated Dienes and Styrene Polymerization

    Directory of Open Access Journals (Sweden)

    Jashvini Jothieswaran

    2017-12-01

    Full Text Available This mini-review focuses on recent advances on the synthesis, structure, and characterization of allyl-based rare earth organometallic complexes, with emphasis on their ability to catalyze the polymerization of non-polar monomers such as conjugated dienes, styrene, and their related copolymerization.

  14. Influence of the degree of hydrolysis of poly(styrene-alt-maleic anhydride) on miscibility with poly(vinyl acetate)

    NARCIS (Netherlands)

    Bosma, M.; Vorenkamp, E.J.; Brinke, G. ten; Challa, G.

    1988-01-01

    The influence of the hydrolysis of anhydride groups in poly(styrene-alt-maleic anhydride) (PSMA) on its miscibility with poly(vinyl acetate) (PVAc) is investigated. The cloudpoint curves of these blends are determined as a function of the degree of hydrolysis. The miscibility is shown to improve

  15. Probing competitive enantioselective approach vectors operating in the Jacobsen-Katsuki epoxidation: a kinetic study of methyl-substituted styrenes.

    Science.gov (United States)

    Fristrup, Peter; Dideriksen, Brian B; Tanner, David; Norrby, Per-Ola

    2005-10-05

    This paper describes a study of reactivity and enantioselectivity for a series of methyl-substituted styrenes in the Jacobsen-Katsuki (Mn(salen)-catalyzed) epoxidation reaction. Competition experiments provided kinetic data for the reactivity of the seven possible methyl-substituted styrenes (mono-, di- and trisubstituted) relative to styrene itself, ee values were measured by chiral GC, and absolute configurations were secured by chemical correlation. Of particular interest was the switch in absolute configuration at the benzylic position of the epoxides derived from (Z)- and (E)-alpha,beta-dimethylstyrene, respectively. The results could be rationalized in terms of an approach vector with the phenyl substituent proximal to the salen. As opposed to alkyl groups, a proximal phenyl group has very little effect on the rate of the reaction. Consideration of distal vs proximal approach allows prediction of absolute stereochemistry as a function of alkene substitution pattern. Trisubstituted alkenes with one phenyl group cis to the alkene hydrogen can be identified as a favored substrate class in the title reaction, with both rate and selectivity close to the classic (Z)-beta-substituted styrene substrates.

  16. BEHAVIOUR OF LISTERIA MONOCYTOGENES IN FRESH SAUCES

    Directory of Open Access Journals (Sweden)

    M.A. Grassi

    2011-01-01

    Full Text Available Ready to use fresh sauces are among Ready to Eat foods for which producers need to respect the 100 UFC/g limit for the presence of L. monocytogenes. In the current research a Challenge test was performed on fresh mushroom and cheese sauces. Both were placed at two storage temperatures and the L. monocytogenes potential growth (d was evaluated. Only cheese sauce stored at 8°C showed a δ> 0,5 log10 UFC/g. However, considering the limited initial contamination it can be excluded that the product could reach 100 UFC/g by the expiration date.

  17. Waste Reduction in Fresh Food Supply Chains

    DEFF Research Database (Denmark)

    Kaipia, Riikka; Loikkanen, Lauri; Dukovska-Popovska, Iskra

    2011-01-01

    The paper studies a well-known phenomenon, information sharing in supply chains, in a new context, fresh foods, with a specific goal, supporting sustainable performance in the supply chain. Fresh foods are important for retail stores, representing around half of retail sales, but form a challenging...... and heterogeneous group of products to manage. The value of the paper lies in its pointing out detailed solutions to how in real-life supply chains data can be used efficiently to improve the performance of the supply chain....

  18. AdS Black Hole with Phantom Scalar Field

    Directory of Open Access Journals (Sweden)

    Limei Zhang

    2017-01-01

    Full Text Available We present an AdS black hole solution with Ricci flat horizon in Einstein-phantom scalar theory. The phantom scalar fields just depend on the transverse coordinates x and y, which are parameterized by the parameter α. We study the thermodynamics of the AdS phantom black hole. Although its horizon is a Ricci flat Euclidean space, we find that the thermodynamical properties of the black hole solution are qualitatively the same as those of AdS Schwarzschild black hole. Namely, there exists a minimal temperature and the large black hole is thermodynamically stable, while the smaller one is unstable, so there is a so-called Hawking-Page phase transition between the large black hole and the thermal gas solution in the AdS space-time in Poincare coordinates. We also calculate the entanglement entropy for a strip geometry dual to the AdS phantom black holes and find that the behavior of the entanglement entropy is qualitatively the same as that of the black hole thermodynamical entropy.

  19. Methods to evaluate fish freshness in research and industry

    DEFF Research Database (Denmark)

    Olafsdottir, G.; Martinsdóttir, E.; Oehlenschläger, J.

    1997-01-01

    methods for the assessment of fish freshness and to discuss the freshness criteria for fish commercialized within the European Union. The project's participants are working in subgroups studying sensory analysis, microbiology, volatile compounds, proteins, lipids, adenosine triphosphate and physical...... measurements with respect to fish freshness evaluation. In this article, the different subgroups have summarized changes that occur in fish and methods to evaluate fish freshness as a first step towards the definition of criteria for fish freshness...

  20. Process Window for Direct Recycling of Acrylonitrile-Butadiene-Styrene and High-Impact Polystyrene from Electrical and Electronic Equipment Waste.

    Science.gov (United States)

    Vazquez, Yamila V; Barbosa, Silvia E

    2017-01-01

    The aim of this paper is to assess recycling process window of ABS (Acrylonitrile-Butadiene-Styrene) and HIPS (High impact Polystyrene) from WEEE (waste from electrical and electronic equipment) through a final properties/structure screening study on their blends. Main motivation is to evaluate which amount of one plastic WEEE can be included into the other at least keeping their properties. In this sense, a wider margin of error during sorting could be admitted to obtain recycling materials with similar technological application of recycled ABS and HIPS by themselves. Results are discussed in terms of final blend structure, focusing in the interaction, within blends, of copolymers phases and fillers presents in WEEE. The comparative analysis of mechanical performance and morphology of HIPS/ABS blends indicates that the addition of 50wt% HIPS to ABS even improves 50% the elongation at break maintaining the strength. On the opposite, HIPS maintains its properties with 20wt% of ABS added. This study allows enlarging composition process window of recycling plastic WEEE for similar applications. This could be a sustainable way to improve benefit of e-scrap with low costs and easy processability. In consequence, social interest in the recycling of this kind of plastic scrap could be encourage from either ecological or economical points of view. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. The use of styrene-butadiene rubber waste as a potential filler in nitrile rubber: order of addition and size of waste particles

    Directory of Open Access Journals (Sweden)

    D. A. Baeta

    2009-03-01

    Full Text Available Styrene-butadiene rubber (SBR has large applications in the shoe industry, especially as expanded sheets used to produce insoles and inner soles. According to TG analysis, the rubber content in SBR residues (SBR-r was found to be around 26-wt%. Based on that data, a cost-effective technique for the reuse of SBR-r in Nitrile rubber (NBR was developed. Later, the effect of SBR-r on the cure behavior, mechanical performance, swelling, and crosslink density of reused rubber was investigated, with more emphasis placed on the effect of both particle size and loading of waste filler. Cure characteristics such as optimum cure time and scorch time were then reduced by the increasing amount of SBR-r filler. Owing to the reinforced nature of the largest particle size SBR-r, the best results for the mechanical properties of NBR were those in which SBR-r was added at the end of the cure process. The study has thus shown that SBR residue (SBR-r can be used as an economical alternative filler in NBR.

  2. Co-recycling of acrylonitrile-butadiene-styrene waste plastic and nonmetal particles from waste printed circuit boards to manufacture reproduction composites.

    Science.gov (United States)

    Sun, Zhixing; Shen, Zhigang; Zhang, Xiaojing; Ma, Shulin

    2015-01-01

    This study investigated the feasibility of using acrylonitrile-butadiene-styrene (ABS) waste plastic and nonmetal particles from waste printed circuit boards (WPCB) to manufacture reproduction composites (RC), with the aim of co-recycling these two waste resources. The composites were prepared in a twin-crew extruder and investigated by means of mechanical testing, in situ flexural observation, thermogravimatric analysis, and dimensional stability evaluation. The results showed that the presence of nonmetal particles significantly improved the mechanical properties and the physical performance of the RC. A loading of 30 wt% nonmetal particles could achieve a flexural strength of 72.6 MPa, a flexural modulus of 3.57 GPa, and an impact strength of 15.5 kJ/m2. Moreover, it was found that the application of maleic anhydride-grafted ABS as compatilizer could effectively promote the interfacial adhesion between the ABS plastic and the nonmetal particles. This research provides a novel method to reuse waste ABS and WPCB nonmetals for manufacturing high value-added product, which represents a promising way for waste recycling and resolving the environmental problem.

  3. Hydrophobic surface modification of TiO2 nanoparticles for production of acrylonitrile-styrene-acrylate terpolymer/TiO2 composited cool materials

    Science.gov (United States)

    Qi, Yanli; Xiang, Bo; Tan, Wubin; Zhang, Jun

    2017-10-01

    Hydrophobic surface modification of TiO2 was conducted for production of acrylonitrile-styrene-acrylate (ASA) terpolymer/titanium dioxide (TiO2) composited cool materials. Different amount of 3-methacryloxypropyl-trimethoxysilane (MPS) was employed to change hydrophilic surface of TiO2 into hydrophobic surface. The hydrophobic organosilane chains were successfully grafted onto TiO2 through Sisbnd Osbnd Ti bonds, which were verified by Fourier transformed infrared spectra and X-ray photoelectron spectroscopy. The water contact angle of the sample added with TiO2 modified by 5 wt% MPS increased from 86° to 113°. Besides, all the ASA/TiO2 composites showed significant improvement in both solar reflectance and cooling property. The reflectance of the composites throughout the near infrared (NIR) region and the whole solar wavelength is increased by 113.92% and 43.35% compared with pristine ASA resin. Simultaneously, significant drop in temperature demonstrates excellent cooling property. A maximum decrease approach to 27 °C was observed in indoor temperature test, while a decrease around 9 °C tested outdoors is achieved.

  4. Poly(acrylonitrile-co-butadiene-co-styrene Reinforced with Hollow Glass Microspheres: Evaluation of Extrusion Parameters and Their Effects on the Composite Properties

    Directory of Open Access Journals (Sweden)

    Marina Panozzo Cunha

    2016-01-01

    Full Text Available Hollow glass microspheres (HGMs filled poly(acrylonitrile-co-butadiene-co-styrene (ABS composites were prepared by means of a twin-screw extruder. S038 HGMs were incorporated at different percentages of 2.5, 5.0, and 7.5 wt%. The HGMs were added into the twin-screw extruder at two different feeding zones, and the effect of HGMs loading and specific feeding zone addition on the composites produced was evaluated with regard to morphological, thermal, rheological, physical, and mechanical properties. As a result, the composite density was reduced while the thermal stability, storage modulus, complex viscosity, and tensile and flexural modulus were improved when compared with the ABS matrix. The results also indicate that the addition of 5.0 wt% of HGMs at the feeding zone closer to the die maintains the integrity of the HGMs and promotes composites with higher mechanical properties and lower density when compared with the composites obtained with the addition of HGMs closer to the hopper.

  5. Risk of cancer in workers exposed to styrene at eight British companies making glass-reinforced plastics.

    Science.gov (United States)

    Coggon, David; Ntani, Georgia; Harris, E Clare; Palmer, Keith T

    2015-03-01

    To provide further information on the risks of lymphohaematopoietic (LH) and other cancers associated with styrene. We extended follow-up to December 2012 for 7970 workers at eight companies in England which used styrene in the manufacture of glass-reinforced plastics. Mortality was compared with that for England and Wales by the person-years method, and summarised by SMRs with 95% CIs. A supplementary nested case-control analysis compared styrene exposures, lagged by 5 years, in 122 incident or fatal cases of LH cancer and 1138 matched controls. A total of 3121 cohort members had died (2022 since the last follow-up). No elevation of mortality was observed for LH cancer, either in the full cohort (62 deaths, SMR 0.90, 95% CI 0.69 to 1.15), or in those with more than background exposure to styrene (38 deaths, SMR 0.82, 95% CI 0.58 to 1.14). Nor did the case-control analysis suggest any association with LH cancer. In comparison with background exposure, the OR for non-Hodgkin's lymphoma/chronic lymphocytic leukaemia in workers with high exposure (estimated 8-h time-weighted average of 40-100 ppm) for ≥1 year was 0.54 (95% CI 0.23 to 1.27). Mortality from lung cancer was significantly elevated, and risk increased progressively across exposure categories, with an SMR of 1.44 (95% CI 1.10 to 1.86) in workers highly exposed for ≥1 year. We found no evidence that styrene causes LH cancer. An association with lung cancer is not consistently supported by other studies. It may have been confounded by smoking, but would be worth checking further. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  6. Applications of Microencapsulated Bifidobacterium Longum with Eleutherine Americana in Fresh Milk Tofu and Pineapple Juice

    Science.gov (United States)

    Phoem, Atchara N.; Chanthachum, Suphitchaya; Voravuthikunchai, Supayang P.

    2015-01-01

    Bifidobacterium longum was microencapsulated by extrusion technique and added in fresh milk tofu and pineapple juice. Microencapsulation of B. longum with Eleutherine americana extract, oligosaccharides extract, and commercial fructo-oligosaccharides was assessed for the bacterial survival after sequential exposure to simulated gastric and intestinal juices, and refrigeration storage. Microencapsulated B. longum with the extract and oligosaccharides extract in the food products showed better survival than free cells under adverse conditions. Sensory analysis demonstrated that the products containing co-encapsulated bacterial cells were more acceptable by consumers than free cells. Pineapple juice prepared with co-encapsulated cells had lower values for over acidification, compared with the juice with free cells added. This work suggested that microencapsulated B. longum with E. americana could enhance functional properties of fresh milk tofu and pineapple juice. PMID:25854832

  7. Revisiting the thermodynamic relations in AdS /CMT models

    Science.gov (United States)

    Hyun, Seungjoon; Park, Sang-A.; Yi, Sang-Heon

    2017-03-01

    Motivated by the recent unified approach to the Smarr-like relation of anti-de Sitter (AdS) planar black holes in conjunction with the quasilocal formalism on conserved charges, we revisit the quantum statistical and thermodynamic relations of hairy AdS planar black holes. By extending the previous results, we identify the hairy contribution in the bulk and show that the holographic computation can be improved so that it is consistent with the bulk computation. We argue that the first law can be retained in its universal form and that the relation between the on-shell renormalized Euclidean action and its free energy interpretation in gravity may also be undeformed even with the hairy contribution in hairy AdS black holes.

  8. Asymptotically AdS spacetimes with a timelike Kasner singularity

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jie [Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2016-07-21

    Exact solutions to Einstein’s equations for holographic models are presented and studied. The IR geometry has a timelike cousin of the Kasner singularity, which is the less generic case of the BKL (Belinski-Khalatnikov-Lifshitz) singularity, and the UV is asymptotically AdS. This solution describes a holographic RG flow between them. The solution’s appearance is an interpolation between the planar AdS black hole and the AdS soliton. The causality constraint is always satisfied. The entanglement entropy and Wilson loops are discussed. The boundary condition for the current-current correlation function and the Laplacian in the IR is examined. There is no infalling wave in the IR, but instead, there is a normalizable solution in the IR. In a special case, a hyperscaling-violating geometry is obtained after a dimensional reduction.

  9. Controlled synthesis of α- and γ-Fe2O3 nanoparticles via thermolysis of PVA gels and studies on α-Fe2O3 catalyzed styrene epoxidation

    Directory of Open Access Journals (Sweden)

    Ruhul A. Bepari

    2017-01-01

    Full Text Available Fe2O3 nanoparticles with diameters in the 7–18 nm range have been synthesized via thermolysis of polyvinyl alcohol (PVA gels prepared under alkaline pH by adding Fe3+ ions into warm aqueous solutions of PVA. While calcinations at 400 °C, 500 °C and 600 °C give γ-Fe2O3 as the pure product, α-Fe2O3 is obtained by heating the gel at 700 °C. It is found that the calcination temperature has a pronounced effect on the nature of the oxide produced but has little effect on particle size. The resultant Fe2O3 nanomaterials are ferromagnetic with moderate coercivities. Preliminary investigations suggest that hematite (α-Fe2O3 nanoparticles effectively catalyze the epoxidation of styrene with tert-butyl hydroperoxide (TBHP as the terminal oxidant.

  10. Synthesis and evaluation of copolymer based on cardanol and styrene on the stability of asphaltenes; Sintese e avaliacao de copolimero a base de cardanol e estireno sobre a estabilidade dos asfaltenos

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, Tatiana S.; Spinelli, Luciana S., E-mail: tatianaloureiro@ima.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Instituto de Macromoleculas

    2015-07-01

    The destabilization of asphaltenes in crude oil mainly happens due to variations in pressure, temperature and oil composition, causing significant losses. Polymers containing specific groups can be used as asphaltenes stabilizers and thus, avoid your precipitation, or as asphaltenes flocculants to assist the removal of suspended particles in a particular oil. The monitoring of asphaltenes precipitation is usually evaluated by tests with variation in stability of asphaltenes in function of adding a flocculant solvent. In this work, it was evaluated the influence of a synthesized copolymer based on cardanol and styrene on the stability of asphaltenes. The stability of asphaltenes was monitored by precipitation tests induced by a flocculant agent (n-heptane), using an ultraviolet-visible (UV-Vis) spectrometer. The structural characterization of copolymer was performed by FTIR and {sup 1}H NMR. The results showed that copolymer can act as asphaltene flocculant. (author)

  11. Consumers’ attitude and opinion towards different types of fresh cheese: an exploratory study

    Directory of Open Access Journals (Sweden)

    Cássia Pereira de BARROS

    2016-01-01

    Full Text Available Abstract Fresh cheese stands out for its tradition and widespread consumption in Brazil. However, there is a lack of information on motivation towards the consumption of available fresh cheeses in the Brazilian market. Focus group sessions were used to explore consumers’ attitude and opinion about fresh cheese. Products with different characteristics were used to stimulate discussion among participants including cheese with “no added salt”, the claim “contains probiotic microorganisms” and products processed with goat milk. The salt content played an important role on the consumer intention to purchase of fresh cheese. Participants stated that they would consume cheese without salt only by following a medical prescription. However, the subjects declared that they would buy reduced salt cheese if such reduction would not compromise the flavor. The meaning of the claim “contains probiotic microorganisms” was often declared as unknown during the discussion. However, they would buy a probiotic product. In addition, it was mentioned that a premium price would be paid for such functional cheese. Participants declared that would buy goat cheese. Nevertheless, to pay a higher price over the conventional one was a controversial and debatable issue among consumers. Results revealed important implications for the development of marketing strategies for fresh cheese.

  12. Domestic fresh soft cheese from Bjelovar

    Directory of Open Access Journals (Sweden)

    Slavko Kirin

    2009-06-01

    Full Text Available This paper shows results of organoleptic properties, physical-chemical composition and microbiological quality investigation of domestic fresh cheese samples taken from Bjelovar market (Croatia. The results were compared to research results obtained from other markets, published by other authors. The main characteristic is great variability that results in unequal quality. Weights of different samples ranged from 610 g to 830 g, with mean value 757.58 g. Cheese consistency shows even greater difference in variety ranging from soft fragmented (28.57 % to firm fragmented (7.14 %. Odour was mostly pleasant and characteristic (71.43 % and taste pleasant, slightly acidic, pure only in 57.14 % of samples. The most common failure in soft cheese organoleptic properties is noticed yeasty odour and taste. Mean value of dry matter was 23.42 g/100 g, and 25.29 g/100 g of fat in dry matter. Acidity of fresh cheese was in pH range from 4.45 to 3.81. Due to the fat content, fresh cheese from Bjelovar is a semi fat fresh cheese, while soft cheeses from researches of other authors are described as low fat cheeses (Pravilnik, 2007. Correlation factor for different characteristics was high. Microbiological analyses show that E. coli was in higher amounts than allowed in 3 of 14 samples, and S. aureus in 2 samples. Microbiological quality is also doubtful because of higher yeasts and mould quantity, which was also concluded by other authors mentioned in this paper.

  13. Influence of Fresh, Composted and Vermicomposted Parthenium ...

    African Journals Online (AJOL)

    A pot culture experiment was carried out to assess the influence of fresh, composted and vermicomposted Parthenium and poultry droppings on the quality parameters of radish like protein, carbohydrates, phenolics, reducing sugar, total soluble sugars and chlorophylls on 45 and 60 DAS (Days After Sowing). The maximum ...

  14. Caribbean fresh and brackish water Chlorophyta

    NARCIS (Netherlands)

    Hoek, van den C.

    1959-01-01

    During his zoological collecting trips to the Antilles Dr. P. Wagenaar Hummelinck also gathered several samples of fresh and brackish water algae, which have been presented to the Rijksherbarium, Leiden. The present paper deals with the Chlorophyta of that collection, with the exception of

  15. Influence of Fresh, Composted and Vermicomposted Parthenium ...

    African Journals Online (AJOL)

    MICHAEL

    ABSTRACT: A pot culture experiment was carried out to assess the influence of fresh, composted and vermicomposted Parthenium and poultry droppings on the quality parameters of radish like protein, carbohydrates, phenolics, reducing sugar, total soluble sugars and chlorophylls on 45 and 60 DAS (Days After Sowing).

  16. Holography in Lovelock Chern-Simons AdS gravity

    Science.gov (United States)

    Cvetković, Branislav; Miskovic, Olivera; Simić, Dejan

    2017-08-01

    We analyze holographic field theory dual to Lovelock Chern-Simons anti-de Sitter (AdS) gravity in higher dimensions using first order formalism. We first find asymptotic symmetries in the AdS sector showing that they consist of local translations, local Lorentz rotations, dilatations and non-Abelian gauge transformations. Then, we compute 1-point functions of energy-momentum and spin currents in a dual conformal field theory and write Ward identities. We find that the holographic theory possesses Weyl anomaly and also breaks non-Abelian gauge symmetry at the quantum level.

  17. AdS5 magnetized solutions in minimal gauged supergravity

    Science.gov (United States)

    Blázquez-Salcedo, Jose Luis; Kunz, Jutta; Navarro-Lérida, Francisco; Radu, Eugen

    2017-08-01

    We construct a generalization of the AdS charged rotating black holes with two equal magnitude angular momenta in five-dimensional minimal gauged supergravity. In addition to the mass, electric charge and angular momentum, the new solutions possess an extra-parameter associated with a non-zero magnitude of the magnetic potential at infinity. In contrast with the known cases, these new black holes possess a non-trivial zero-horizon size limit which describes a one parameter family of spinning charged solitons. All configurations reported in this work approach asymptotically an AdS5 spacetime in global coordinates and are free of pathologies.

  18. AdS5 magnetized solutions in minimal gauged supergravity

    Directory of Open Access Journals (Sweden)

    Jose Luis Blázquez-Salcedo

    2017-08-01

    Full Text Available We construct a generalization of the AdS charged rotating black holes with two equal magnitude angular momenta in five-dimensional minimal gauged supergravity. In addition to the mass, electric charge and angular momentum, the new solutions possess an extra-parameter associated with a non-zero magnitude of the magnetic potential at infinity. In contrast with the known cases, these new black holes possess a non-trivial zero-horizon size limit which describes a one parameter family of spinning charged solitons. All configurations reported in this work approach asymptotically an AdS5 spacetime in global coordinates and are free of pathologies.

  19. Loops in AdS from conformal field theory

    Science.gov (United States)

    Aharony, Ofer; Alday, Luis F.; Bissi, Agnese; Perlmutter, Eric

    2017-07-01

    We propose and demonstrate a new use for conformal field theory (CFT) crossing equations in the context of AdS/CFT: the computation of loop amplitudes in AdS, dual to non-planar correlators in holographic CFTs. Loops in AdS are largely unexplored, mostly due to technical difficulties in direct calculations. We revisit this problem, and the dual 1 /N expansion of CFTs, in two independent ways. The first is to show how to explicitly solve the crossing equations to the first subleading order in 1 /N 2, given a leading order solution. This is done as a systematic expansion in inverse powers of the spin, to all orders. These expansions can be resummed, leading to the CFT data for finite values of the spin. Our second approach involves Mellin space. We show how the polar part of the four-point, loop-level Mellin amplitudes can be fully reconstructed from the leading-order data. The anomalous dimensions computed with both methods agree. In the case of ϕ 4 theory in AdS, our crossing solution reproduces a previous computation of the one-loop bubble diagram. We can go further, deriving the four-point scalar triangle diagram in AdS, which had never been computed. In the process, we show how to analytically derive anomalous dimensions from Mellin amplitudes with an infinite series of poles, and discuss applications to more complicated cases such as the N = 4 super-Yang-Mills theory.

  20. Preparing cellulose nanocrystal/acrylonitrile-butadiene-styrene nanocomposites using the master-batch method.

    Science.gov (United States)

    Ma, Libo; Zhang, Yang; Meng, Yujie; Anusonti-Inthra, Phuriwat; Wang, Siqun

    2015-07-10

    The master-batch method provides a simple way to apply cellulose nanocrystal (CNC) as reinforcement in a hydrophobic matrix. The two-stage process includes making high-CNC content (70 wt%) master batch pellets, then mixing acrylonitrile-butadiene-styrene (ABS) and maleic anhydride grafted polyethylene with the master batch pellets to prepare the ABS/CNC nanocomposite in extruder. SEM image indicates that self-assembled CNC nanosheets disperse evenly throughout the polymer matrix. The improved mechanical properties shown in tensile and DMA tests reveal that the CNC combines well with the ABS. TGA results show that the thermal degradation temperature of CNC in the master batch increases because of the protection of the ABS coating. This approach not only improves the dispersion ability and the thermal stability of CNC, but it is also applicable to use with other hydrophobic thermoplastics in industrial scale production. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Interactions between halloysite nanotubes and poly(styrene sulfonate) in solution

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Heon; Ryu, Jung Ju; Shin, Joo Huei; Lee, Hoik; Sohn, Dae Won [Dept. of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul (Korea, Republic of); Kim, Ick Soo [Nano Fusion Technology Research Lab, Division of Frontier Fibers, Institute for Fiber Engineering (IFES), Interdisciplinary Cluster for Cutting Edge Research (ICCER), Shinshu University, Nagano (Japan)

    2017-01-15

    The interaction between halloysite nanotubes (HNT) and poly(styrene sulfonate) (PSS) in aqueous solution was investigated by dynamic light scattering. Dynamic behavior of HNT/PSS was observed with different salt, HNT, and PSS concentrations. The HNT colloids were stabilized by PSS over a wide range of HNT concentrations, and HNT suspension in dilute solution formed stable HNT/PSS particles. On the other hand, HNT particles aggregated as sediments at higher concentrations due to strong attraction among HNT rods, and HNT aggregates were stabilized by additional PSS. The interactions between HNT and PSS are described by the van der Waals–London force (VDWL). The stabilization process of HNT/PSS particles in salt solution was proposed by comparing the hydrodynamic radii and apparent intensities of samples. The results demonstrate that electrostatic, steric, and depletion stabilization processes are responsible for the stable dispersion of HNT even at high concentration.

  2. Biodegradation behavior of styrene butadiene rubber (SBR) reinforced with modified coconut shell powder

    Science.gov (United States)

    Sreejith, M. P.; Balan, Aparna K.; Shaniba, V.; Jinitha, T. V.; Subair, N.; Purushothaman, E.

    2017-06-01

    Biodegradation behavior of styrene butadiene rubber composites reinforced with natural filler, coconut shell powder (CSP), with different filler loadings were carried out under soil burial conditions for three to six months. The extent of biodegradation of the composites was evaluated through weight loss, tensile strength and hardness measurements. It was observed that the permanence of the composites was remarkably dependent on filler modification, size of the filler particle and filler content. Composites containing silane modified filler were found to be more resistant to attack by the microbes present in the soil. Mechanical properties such as tensile strength, Young's modulus and hardness were decreased after soil burial testing due to the microbial attack onto the samples.

  3. Nitroxide-Mediated Radical Polymerization of Styrene Initiated from the Surface of Titanium Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    M. Abbasian

    2016-01-01

    Full Text Available Titanium dioxide (TiO2 nanoparticles, with an average size of about 45 nm, were encapsulated by polystyrene using in situ nitroxide mediated radical polymerization   in the presence of 3-aminopropyl triethoxy silane (APTES as a coupling agent and 2, 2, 6, 6-tetramethylpiperidinyl-1-oxy  as a initiator. First, the initiator for NMRP was covalently bonded onto the surface of Titanium dioxide nanoparticles through our novel method. For this purpose, the surface of TiO2 nanoparticle was treated with 3-aminopropyl triethoxy silane, a silane coupling agent, and then these functionalized nanoparticles was reacted with ±-chloro phenyl acetyl chloride. The chlorine groups were converted to nitroxide mediated groups by coupling with 1-hydroxy-2, 2, 6, 6-tetramethyl piperidine. These modified TiO2 nanoparticles were then dispersed in styrene (St monomers to carry out the in situ free radical polymerization.

  4. Prediction of the Styrene Butadiene Rubber Performance by Emulsion Polymerization Using Backpropagation Neural Network

    Directory of Open Access Journals (Sweden)

    Yan-jiang Jin

    2013-01-01

    Full Text Available The effect of the amounts of initiator, emulsifier, and molecular weight regulator on the styrene butadiene rubber performance was investigated, based on the industrial original formula. It was found that the polymerization rate was increased with the increased dosage of initiator and emulsifier, and together with replenishing molecular weight regulator will make the Mooney viscosity of rubber meet the national standard when the conversion rate reaches 70%. The backpropagation neural network was trained by the original formula and ameliorated formula on the basis of Levenberg-Marquardt algorithm, and the relative error between the simulation results and experimental data is less than 1%. The good consistency shows that the BP neural network could predict the product performances in different formula conditions. It would pave the way for adjustment of the SBR formulation and prediction of the product performances.

  5. Co-metabolic formation of substituted phenylacetic acids by styrene-degrading bacteria

    Directory of Open Access Journals (Sweden)

    Michel Oelschlägel

    2015-06-01

    The styrene-degrading strains Rhodococcus opacus 1CP, Pseudomonas fluorescens ST, and the novel isolates Sphingopyxis sp. Kp5.2 and Gordonia sp. CWB2 were investigated with respect to their applicability to co-metabolically produce substituted phenylacetic acids. Isolates were found to differ significantly in substrate tolerance and biotransformation yields. Especially, P. fluorescens ST was identified as a promising candidate for the production of several phenylacetic acids. The biotransformation of 4-chlorostyrene with cells of strain ST was shown to be stable over a period of more than 200 days and yielded about 38 mmolproduct gcelldryweight−1 after nearly 350 days. Moreover, 4-chloro-α-methylstyrene was predominantly converted to the (S-enantiomer of the acid with 40% enantiomeric excess.

  6. Kinetic Investigation of Styrene Free Radical Polymerization by Using Binary Mixtures of Monofunctional Initiators

    Directory of Open Access Journals (Sweden)

    Farshid Ziaee

    2013-01-01

    Full Text Available Polymerization of styrene in presence of two monofunctional initiators is studied kinetically in an ampoule scale. Polymerizations were ceased at different conversions for each ampoule while the temperature was increased almost linearly during the reaction. Three different initiator mixtures were used. The first mixtures were composed of benzoil peroxide (BPO and t-butyl perbenzoate (TBPB with various molar ratios and temperature programs. The second and third series were performed on mixtures of BPO and α,α'-azobisisobutyronitrile (AIBN and AIBN with TBPB, respectively. The experimental results for these series revealed thatincreasing the percentage of TBPB in the initiator mixtures at the same reaction temperature intervals enhanced polymerization rate and molecular weight of the resulting polymers. On the other hand the results from the second series indicated that reducing AIBN in the mixture would have reduction effect on the reaction temperatureintervals while both conversion and the polymer molecular weight are increased

  7. Going greener: Synthesis of fully biobased unsaturated polyesters for styrene crosslinked resins with enhanced thermomechanical properties

    Directory of Open Access Journals (Sweden)

    C. S. M. F. Costa

    2017-11-01

    Full Text Available The main goal of this work was the development of fully biobased unsaturated polyesters (UPs that upon crosslinking with unsaturated monomers (UM could lead to greener unsaturated polyester resins (UPRs with similar thermomechanical properties to commercial fossil based UPR. After the successful synthesis of the biobased UPs, those were crosslinked with styrene (Sty, the most commonly used monomer, and the influence of the chemical structure of the UPs on the thermomechanical characteristics of UPRs were evaluated. The properties were compared with those of a commercial resin (Resipur 9837©. The BioUPRs presented high gel contents and contact angles that are similar to the commercial resin. The thermomechanical properties were evaluated by dynamic mechanical thermal analysis (DMTA and it was found that the UPR synthesized using propylene glycol (PG, succinic acid (SuAc and itaconic acid (ItAc presented very close thermomechanical properties compared to the commercial resin.

  8. Performance of asphaltic concrete incorporating styrene butadiene rubber subjected to varying aging condition

    Science.gov (United States)

    Salah, Faisal Mohammed; Jaya, Ramadhansyah Putra; Mohamed, Azman; Hassan, Norhidayah Abdul; Rosni, Nurul Najihah Mad; Mohamed, Abdullahi Ali; Agussabti

    2017-12-01

    The influence of styrene butadiene rubber (SBR) on asphaltic concrete properties at different aging conditions was presented in this study. These aging conditions were named as un-aged, short-term, and long-term aging. The conventional asphalt binder of penetration grade 60/70 was used in this work. Four different levels of SBR addition were employed (i.e., 0 %, 1 %, 3 %, and 5 % by binder weight). Asphalt concrete mixes were prepared at selected optimum asphalt content (5 %). The performance was evaluated based on Marshall Stability, resilient modulus, and dynamic creep tests. Results indicated the improving stability and permanent deformation characteristics that the mixes modified with SBR polymer have under aging conditions. The result also showed that the stability, resilient modulus, and dynamic creep tests have the highest rates compared to the short-term aging and un-aged samples. Thus, the use of 5 % SBR can produce more durable asphalt concrete mixtures with better serviceability.

  9. Morphological and mechanical properties of styrene butadiene rubber/nano copper nanocomposites

    Directory of Open Access Journals (Sweden)

    Maryam Hadizadeh Harandi

    Full Text Available In this research, rubber based nanocomposites with presence of nanoparticle has been studied. Styrene butadiene rubber (SBR/nanocopper (NC composites were prepared using two-roll mill method. Transmission electron microscope (TEM and scanning electron microscope (SEM images showed proper dispersion of NC in the SBR matrix without substantial agglomeration of nanoparticles. To evaluate the curing properties of nanocomposite samples, swelling and cure rheometric tests were conducted. Moreover, the rheological studies were carried out over a range of shear rates. The effect of NC particles was examined on the thermal behavior of the SBR using thermal gravimetric analysis (TGA. Furthermore, tensile tests were employed to investigate the capability of nanoparticles to enhance mechanical behavior of the compounds. The results showed enhancement in tensile properties with incorporation of NC to SBR matrix. Moreover, addition of NC increased shear viscosity and curing time of SBR composites. Keywords: Nanocopper, Rubber, Curing behavior, Rheological properties, Thermal stability, Tensile characteristics

  10. Effect of gamma irradiation on the properties of natural rubber/styrene butadiene rubber blends

    Directory of Open Access Journals (Sweden)

    A.B. Moustafa

    2016-09-01

    Full Text Available Blends of natural rubber (NR with styrene butadiene rubber (SBR with varying ratios have been prepared. Vulcanization of the prepared blends has been induced by irradiation of gamma rays with varying doses up to 250 kGy. Mechanical properties, namely tensile strength, tensile modulus at 100% elongation, elongation at break have been followed up as a function of irradiation dose as well as blend composition. Physical properties, namely gel fraction and swelling number have been followed up using benzene as a solvent. Thermal measurements namely thermogravimetric analysis were carried out. The results indicated that the addition of NR has improved the properties of NR / SBR blends. Also NR/SBR blend is thermally stable than NR alone.

  11. Microstructural analysis of carbon nanotubes produced from pyrolysis/combustion of styrene-butadiene rubber

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Joner O.; Zhuo, Chuanwei; Levendis, Yannis A. [Northeastern Univ., Boston, MA (United States). Coll. of Engineering. Dept. of Mechanical and Industrial Engineering; Tenorio, Jorge A.S. [University of Sao Paulo (USP), SP (Brazil). Polytechnic School. Dept. of Metallurgical and Materials Engineering

    2010-07-01

    Styrene-Butadiene-Rubber (SBR) is a synthetic rubber copolymer used to fabricate several products. This study aims to demonstrate the use of SBR as feedstock for carbon nanotubes (CNTs) growth, and therefore to establish a novel process for destination for wastes produced from SBR. Pellets of this rubber were controlled burned at temperature of 1000 deg C, and a catalyst system was used to synthesize the nanomaterials. CNTs are materials with a wide range of potential applications due to their extraordinary mechanical, thermal and electrical properties. Produced materials were characterized by SEM and TEM, and the hydrocarbons emissions were measured using GC. Results showed that materials with diameters of 30-100 nm and lengths of about 30 {mu}m were formed. That materials presented similar structures of multi-walled CNTs. Therefore, the use of SBR to produce carbon nanotubes showed quite satisfactory and an interesting field for future investments. (author)

  12. The migration of acrylonitrile from acrylonitrile/butadiene/styrene polymers into food-simulating liquids.

    Science.gov (United States)

    Lickly, T D; Markham, D A; Rainey, M L

    1991-01-01

    The correlation of residual acrylonitrile (AN) monomer concentration in AN-containing polymers with AN migration into food simulants is of interest because the US FDA regulates the use of these polymers on the basis of the amount of AN that may migrate into food simulants. Studies of the migration of AN into water from seven acrylonitrile/butadiene/styrene polymers with varying composition and residual AN levels showed that a linear relationship exists between the concentration of AN in the polymer and the amount of AN migrating, for a given set of exposure conditions. A linear relationship was also observed between the diffusion coefficients generated from the experimental data using a simple Fickian diffusion model and the inverse of the absolute temperature of exposure.

  13. N-containing carbons from styrene-divinylbenzene copolymer by urea treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhuravsky, Sergey V.; Kartel, Mykola T.; Tarasenko, Yuriy O. [Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 17 General Naumov Street, Kiev, 03164 (Ukraine); Villar-Rodil, Silvia [Instituto Nacional del Carbon, INCAR-CSIC, Apartado 73, 33080 Oviedo (Spain); Dobos, Gabor [Department of Atomic Physics, Budapest University of Technology and Economics, H-1521 Budapest (Hungary); Toth, Ajna [Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, PO Box 92 (Hungary); Tascon, Juan M.D. [Instituto Nacional del Carbon, INCAR-CSIC, Apartado 73, 33080 Oviedo (Spain); Laszlo, Krisztina, E-mail: klaszlo@mail.bme.hu [Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, PO Box 92 (Hungary)

    2012-01-15

    N-containing synthetic carbons with narrow porosity were prepared from a chlorinated styrene and divinylbenzene copolymer by a multistep method with a yield of 34 wt%. Surface chemical treatment and thermal carbonization of the starting copolymer was monitored by urea impregnation. Steam activation, oxidation and an additional heat treatment gave the final product. The synthesis route was designed in a cost-effective way. The porosity and the concentration of the introduced nitrogen atoms were determined at each step. The final product has a surface area of 1135 m{sup 2}/g. More than 70% of the pore volume comes from micropores with an average width of 0.7 nm. The 2.3 at.% surface nitrogen atoms are distributed among five detectable species, of which about 44% is quaternary nitrogen.

  14. Direct Synthesis of Polymer Nanotubes via Aqueous Dispersion Polymerization of Cyclodextrin/Styrene Complex.

    Science.gov (United States)

    Chen, Xi; Liu, Lei; Huo, Meng; Zeng, Min; Peng, Liao; Feng, Anchao; Wang, Xiaosong; Yuan, Jinying

    2017-10-17

    We report a one-step synthesis of nanotubes by RAFT dispersion polymerization of cyclodextrin/styrene (CD/St) complexes directly in water. The resulted amphiphilic PEG-b-PS diblock copolymers self-assemble in situ into nanoparticles with various morphologies. Spheres, worms, lamellae, and nanotubes were controllably obtained. Because of the complexation, the swelling degree of polystyrene (PS) blocks by free St is limited, resulting limited mobility of PS chains. Consequently, kinetically trapped lamellae and nanotubes were obtained instead of spherical vesicles. During the formation of nanotubes, small vesicles firstly formed at the ends of the tape-like lamellae, then grew and fused into nanotubes with limited chain rearrangement. The introduction of host-guest interaction based on CDs enables the aqueous dispersion polymerization of water-immiscible monomers, and produces kinetically trapped nanostructures, which could be a powerful technique for nanomaterials synthesis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Thermo-Physical Properties of Kenaf-Filled Acrylonitrile Butadiene Styrene Composites

    Directory of Open Access Journals (Sweden)

    Nikmatin Siti

    2017-01-01

    Full Text Available Studies on advantageous of natural fillers incorporated into polymer composites on thermo-physical and mechanical properties are still intensively investigated. Several evidences suggest that the natural fillers with small contents combined with polymer increase their composite properties. We thus investigate thermo-physical properties of kenaf-filled acrylonitrile butadiene styrene (ABS composites. ABS with 5% kenaf microparticle size (ABS/K5, ABS with 5% kenaf short fiber (ABS/KSF5, and recycled ABS with 5% kenaf microparticle size (RABS/K5 were manufactured. Granular composites were manufactured by the twin screw extruder. Composite properties in terms of X-ray diffractions, surface morphologies, and thermal behaviors were investigated. The present work found that ABS/KSF5 has the highest degree of crystallinity compared to others. No significant difference was found in terms of thermal properties of the composites.

  16. Radiation-induced degradation of poly(styrene-co-methylmethacrylate) and blends of polystyrene and polymethylmethacrylate

    Science.gov (United States)

    Torikai, Ayako; Harayama, Ken-Ichi; Hayashi, Nobutomo; Mitsuoka, Takuya; Fueki, Kenji

    1994-05-01

    The γ-ray-induced degradation of poly(styrene-co-methyl-methacrylate) [poly(St-co-MMA)] and blends of polystyrene (PSt) and polymethylmethacrylate (PMMA) was investigated by ultraviolet (UV), Fourier transform infrared (FTIR) spectroscopy and viscosity measurements. The optical density around 250 nm decreases linearly with the electron fraction of PSt in the blends, but this does not hold in case of the degradation of poly(St-co-MMA). Similar trends are seen for the decrease in the amount of ester groups, oxidation product formation and the number of chain scission (Cs). A protective effect due to the St component was observed in case of the degradation of poly(St-co-MMA), but it was not observed for the blends. The spatial extent of protection affected by St unit was deduced by assuming a random distribution of MMA and St throughout the copolymer molecule.

  17. Enantioselective resolution of racemic styrene oxide at high concentration using recombinant Pichia pastoris expressing epoxide hydrolase of Rhodotorula glutinis in the presence of surfactant and glycerol.

    Science.gov (United States)

    Yoo, Seung Sik; Park, Sunghoon; Lee, Eun Yeol

    2008-10-01

    The reaction medium was optimized to accomplish epoxide hydrolase-catalyzed, batch enantioselective hydrolysis of racemic styrene oxide at high initial substrate concentrations. The recombinant Pichia pastoris containing the epoxide hydrolase gene of Rhodotorula glutinis was used as the biocatalyst. Enantiopure (S)-styrene oxide with 98% ee was obtained with 41% yield (maximum yield = 50%) from 1.8 M racemic styrene oxide at pH 8.0, 4 degrees C in the presence of 40% (v/v) Tween 20 and 5% (v/v) glycerol.

  18. Mechanical behavior of styrene grafted PVC films by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Jessica R.; Moura, Eduardo; Somessari, Elisabeth S.R.; Silveira, Carlos G.; Paes, Helio A.; Souza, Carlos A.; Manzoli, Jose E.; Geraldo, Aurea B.C., E-mail: ageraldo@ipen.br, E-mail: jmanzoli@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The polyvinyl chloride (PVC) is a technological and low cost polymer, however it presents high sensitivity to high energy irradiation because of the weakness of carbon-chloride bond face to carbon-carbon and carbon-hydrogen bonds. Grafting is a type of co-polymerization process that can allow it an increase of mechanical characteristics. The aim of this work is to evaluate the mechanical properties of styrene grafted PVC by electron beam irradiation using mutual and pre-irradiation methods to verify the mechanical resistance changes of obtained product whether grafting process is applied from non-irradiated or from pre-irradiated substrates. The irradiation procedures were performed in atmosphere air or inert atmosphere and the irradiation conditions comprised doses from 10 kGy to 100 kGy and dose rates of 2.2 kGy/s and 22.4 kGy/s. The styrene grafted samples were analyzed by gravimetry to determinate the grafting yield; the final values have been averaged from a series of three measurements. The Mid-A TR-FTIR was the spectrophotometer technique used for qualitative/semi-quantitative analysis of grafted samples. The Young's module and tensile strength of pre-irradiated and grafted PVC samples at both methods were measured at a Lloyd LXR tensile tester at a cross-head speed of 10.00 mm/min. We observed the decrease of Young's module and tensile strength with the increase of absorbed dose at pre-irradiated PVC samples. These mechanical parameters results are discussed. (author)

  19. Anionic Polymerization of Styrene and 1,3-Butadiene in the Presence of Phosphazene Superbases

    KAUST Repository

    Ntetsikas, Konstantinos

    2017-10-23

    The anionic polymerization of styrene and 1,3-butadiene in the presence of phosphazene bases (t-BuP4, t-BuP2 and t-BuP1), in benzene at room temperature, was studied. When t-BuP1 was used, the polymerization proceeded in a controlled manner, whereas the obtained homopolymers exhibited the desired molecular weights and narrow polydispersity (Ð < 1.05). In the case of t-BuP2, homopolymers with higher than the theoretical molecular weights and relatively low polydispersity were obtained. On the other hand, in the presence of t-BuP4, the polymerization of styrene was uncontrolled due to the high reactivity of the formed carbanion. The kinetic studies from the polymerization of both monomers showed that the reaction rate follows the order of [t-BuP4]/[sec-BuLi] >>> [t-BuP2]/[sec-BuLi] >> [t-BuP1]/[sec-BuLi] > sec-BuLi. Furthermore, the addition of t-BuP2 and t-BuP1 prior the polymerization of 1,3-butadiene allowed the synthesis of polybutadiene with a high 1,2-microstructure (~45 wt %), due to the delocalization of the negative charge. Finally, the one pot synthesis of well-defined polyester-based copolymers [PS-b-PCL and PS-b-PLLA, PS: Polystyrene, PCL: Poly(ε-caprolactone) and PLLA: Poly(L-lactide)], with predictable molecular weights and a narrow molecular weight distribution (Ð < 1.2), was achieved by sequential copolymerization in the presence of t-BuP2 and t-BuP1.

  20. Stereoregularity evolution of isobornyl acrylate and styrene copolymers by 2D NMR spectroscopy

    Science.gov (United States)

    Khandelwal, Deepika; Hooda, Sunita; Brar, A. S.; Shankar, Ravi

    2013-10-01

    Isobornyl acrylate/styrene (B/S) copolymers of different compositions have been prepared by Atom Transfer Radical Polymerization (ATRP) using methyl-2-bromopropionate as an initiator and PMDETA/CuBr as catalyst under nitrogen atmosphere at 60 °C. Copolymer compositions calculated from 1H NMR spectra are used to determine the reactivity ratios of monomers. Linear Kelen-Tudos (KT) and non-linear error in variable methods (EVM) have been employed for determination of monomer reactivity ratios in copolymers. The reactivity ratios obtained from KT and EVM are found to be rB = 0.41 ± 0.08, rS = 0.92 ± 0.13 and rB = 0.41 and rS = 0.93 respectively. These copolymers have been analyzed for their stereochemical structure using various 1D (1H, 13C{1H}, DEPT) and 2D (HSQC, TOCSY, NOESY, HMBC) NMR techniques. 2D HSQC and TOCSY NMR experiments are employed to resolve the highly overlapped and complex 1H and 13C{1H} NMR spectra of the copolymers. Spatial coupling of different types of protons are resolved by 2D NOESY NMR spectra. The configurational and compositional sequences of β-methylene carbons are assigned upto tetrad level whereas methine carbon is assigned as triad level of compositional sequences. The quaternary carbon of styrene and carbonyl carbon of isobornyl acrylate have been assigned as triad level of compositional sequences and are further confirmed by 2D HMBC NMR spectra.

  1. PENGARUH TEMPERATUR TERHADAP TINGKAT SERAPAN AIR DALAM BAHAN POLY (2-VINYL PYRIDINE -CO-STYRENE

    Directory of Open Access Journals (Sweden)

    Mr Wiendartun

    2015-01-01

    Full Text Available Hydrophilic properties of organic polymer such as Poly (2-Vinylpyridine- Co-Styrene have been found to have a correlation with other physical properties especially the electric resistivity. In this work, we have studied one of the physical properties of a polymer material, Poly (2-Vinylpyridine- Co-Styrene, that is the electric resistivity. It was studied on the basis of its relation with the concentration, temperature, humidity and the distance between their electrodes. The sample fabricated consists of two types of consentration: 0.03 gr/ml and 0.05 gr/ml with the distance between the two electrodes are 0.40 mm and 0.80 mm respectively. Towards these samples, we investigated the resistance coefficient for every 2% change in humidity for both drying and watering processes. From the experiment we obtain the following results: 1 There is hysteresis during the watering and drying processes indicating the continuity of resistance of this material, 2 Sample with smaller distance of electrodes performs better than that of the longer ones, 3 Sample fabricated from solution with higher concentration performs better than that of the lower ones, 4 Room temperature plays a significant role on the performance of the polymer material between the associated electrodes. These results could be used as a stepping-stone toward the more advance research leading the determination of film stability, resistancy upon temperature variation etc, so that this polymer material could be further developed into the humidity sensor device material. Key words: Hydrophilic, electric resistance, humidity sensor and polymer.

  2. Proton conductive membranes based on poly (styrene-co-allyl alcohol semi-IPN

    Directory of Open Access Journals (Sweden)

    Felipe Augusto Moro Loureiro

    2014-01-01

    Full Text Available The optimization of fuel cell materials, particularly polymer membranes, for PEMFC has driven the development of methods and alternatives to achieve systems with more adequate properties to this application. The sulfonation of poly (styrene-co-allyl alcohol (PSAA, using sulfonating agent:styrene ratios of 2:1, 1:1, 1:2, 1:4, 1:6, 1:8 and 1:10, was previously performed to obtain proton conductive polymer membranes. Most of those membranes exhibited solubility in water with increasing temperature and showed conductivity of approximately 10-5 S cm-1. In order to optimize the PSAA properties, especially decreasing its solubility, semi-IPN (SIPN membranes are proposed in the present study. These membranes were obtained from the diglycidyl ether of bisphenol A (DGEBA, curing reactions in presence of DDS (4,4-diaminodiphenyl sulfone and PSAA. Different DGEBA/PSAA weight ratios were employed, varying the PSAA concentration between 9 and 50% and keeping the mass ratio of DGEBA:DDS as 1:1. The samples were characterized by FTIR and by electrochemical impedance spectroscopy. Unperturbed bands of PSAA were observed in the FTIR spectra of membranes, suggesting that chemical integrity of the polymer is maintained during the synthesis. In particular, bands involving C-C stretching (1450 cm-1, C=C (aromatic, ~ 3030 cm-1 and C-H (2818 and 2928 cm-1 were observed, unchanged after the synthesis. The disappearance or reduction of the intensity of the band at 916 cm-1, attributed to the DGEBA epoxy ring, is evidenced for all samples, indicating the epoxy ring opening and the DGEBA crosslinking. Conductivity of H3PO4 doped membranes increases with temperature, reaching 10-4 S cm-1.

  3. Kinetics modeling of ethylbenzene dehydrogenation to styrene over a mesoporous alumina supported iron catalyst

    KAUST Repository

    Hossain, Mohammad M.

    2012-10-01

    The kinetics of ethylbenzene (EB) dehydrogenation over a FeO x-meso-Al 2O 3 catalyst is studied. The models were developed based on physicochemical characterization and a CREC fluidized Riser Simulator data. N 2 adsorption shows that the synthesized FeO x-meso-Al 2O 3 catalyst is mesoporous with pore size between 9 and 35nm. TPR profile indicates that iron on meso-Al 2O 3 forms easily reducible nanostructured crystals which is confirmed by TEM image. NH 3- and CO-TPD analysis, respectively reveals the availability of both acidic and basic sites. The dehydrogenation of ethylbenzene on FeO x-meso-Al 2O 3 catalyst mainly gives styrene (∼99%) while a small amount of benzene, toluene and coke are also detected. Based on the experimental observations two Langmuir-Hinshelwood type kinetics models are formulated. The possible catalyst deactivation is expressed as function of EB conversion. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one type site Langmuir-Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the physical constraints. The activation energy for the formation of styrene (80kJ/mol) found to be significantly lower than that of the undesired products benzene (144kJ/mol) and toluene (164kJ/mol). The estimated heat of adsorptions of EB and ST are found to be 55kJ/mol and 19kJ/mol, respectively. © 2012 Elsevier B.V.

  4. Compatibility, Morphology, Mechanical Properties and Biodegradability of Poly(styrene-ethylene-propylenestyrene/ Modified Thermoplastic Starch Blends

    Directory of Open Access Journals (Sweden)

    Saaid Rahimi Bandarabadi

    2016-09-01

    Full Text Available The effect of modified starch on the properties of poly(styrene-ethylenepropylene- styrene tri-block copolymer was studied. Chemical treatment of starch with maleic anhydride was accomplished in an internal mixer in the presence of glycerol. The reaction was confirmed using Fourier infrared spectroscopy (FTIR and titration. The blend samples containing 10, 20, 30 and 50 wt% were obtained by melt blending and their mechanical, morphological and dynamic-mechanical properties were studied. Scanning electron microscopy (SEM images displayed droplet-matrix morphology and with increases in modified starch up to 50 wt% some partial co-continuous morphology was also observed. With increase of modified starch in the compound, the size of dispersed phase increased. DMTA results revealed that the partial compatibility was obtained because of slight difference between glass transition temperatures of two phases in the presence of modified starch. The peak of modified starch shifted to higher values and the differences between the two peaks decreased, indicating partial compatibility. Mechanical properties including tensile, elongation-at-break and modulus were also determined and the results showed that the mechanical properties of the sample were higher than those of neat TPS because of the higher compatibility. Tensile strength was decreased with increase in modified starch content due to the absence of strong interfacial adhesion. Moduli of the samples were increased with increase in modified starch content due to higher stiffness of starch. Biodegradability of the samples was evaluated by weight loss percentage using compost test. A rapid degradation was observed in the first 45 days and with increase of the modified starch content the degree of degradation was increased.

  5. Thermal degradation kinetics of polyketone based on styrene and carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Jiali, E-mail: jiaqm411@163.com; Fan, Wenjun; Shan, Shaoyun; Su, Hongying; Wu, Shuisheng; Jia, Qingming

    2014-03-01

    Highlights: • The PK were synthesized from carbon monoxide and styrene in the presence of PANI-PdCl{sub 2} catalyst and PdCl{sub 2} catalyst. • The structures and thermal behaviors of PK prepared by homogenous and the supported catalyst were investigated. • The microstructures of PK were changed in the supported catalyst system. • The alternating PK copolymer (PANI-PdCl{sub 2} catalyst) was more thermally stable than PK (PdCl{sub 2} catalyst). • The degradation activation energy values were estimated by Flynn–Wall–Ozawa method and Kissinger method. - Abstract: Copolymerization of styrene with carbon monoxide to give polyketones (PK) was carried out under homogeneous palladium catalyst and polyaniline (PANI) supported palladium(II) catalyst, respectively. The copolymers were characterized by {sup 1}H NMR, {sup 13}C NMR and GPC. The results indicated that the PK catalyzed by the supported catalyst has narrow molecular weight distribution (PDI = 1.18). For comparison purpose of thermal behaviors of PK prepared by the homogeneous and the supported catalyst, thermogravimetric (TG) analysis and derivative thermogravimetric (DTG) were conducted at different heating rates. The peak temperatures (396–402 °C) for PK prepared by the supported catalyst are higher than those (387–395 °C) of PK prepared by the homogeneous catalyst. The degradation activation energy (E{sub k}) values were estimated by Flynn–Wall–Ozawa method and Kissinger method, respectively. The E{sub k} values, as determined by two methods, were found to be in the range 270.72 ± 0.03–297.55 ± 0.10 kJ mol{sup −1}. Structures analysis and thermal degradation analysis revealed that the supported catalyst changed the microstructures of PK, resulting in improving thermal stability of PK.

  6. Perinatal Toxicity and Carcinogenicity Studies of Styrene –Acrylonitrile Trimer, A Ground Water Contaminant

    Science.gov (United States)

    Behl, Mamta; Elmore, Susan A.; Malarkey, David E.; Hejtmancik, Milton R.; Gerken, Diane K.; Chhabra, Rajendra S.

    2015-01-01

    Styrene Acrylonitrile (SAN) Trimer is a by-product in the production of acrylonitrile styrene plastics. Following a report of a childhood cancer cluster in the Toms River section of Dover Township, New Jersey, SAN Trimer was identified as one of the groundwater contaminants at Reich Farm Superfund site in the township. The contaminants from the Reich Farm site’s ground water plume impacted two wells at the Parkway well field. The National Toxicology Program (NTP) studied the toxicity and carcinogenicity of SAN Trimer in rats exposed during their perinatal developmental period and adulthood. The chronic toxicity and carcinogenicity studies in F344/N rats were preceded by 7- and 18-week perinatal toxicity studies to determine the exposure concentrations for the 2-year studies. Subsequently, Fisher 344 pregnant dams were exposed to SAN Trimer containing diet at 400, 800, or 1600 ppm concentrations during gestation, nursing and weaning periods of offspring followed by two year of adult exposures to both male and female pups. There was no statistically significant evidence of carcinogenic activity following SAN-Trimer exposure; however, rare neoplasms in the brain and spinal cord were observed in males and to lesser extent in female rats. These incidences were considered within the range of historical background in the animal model used in the current studies. Therefore, the presence of a few rarely occurring CNS tumors in the treated groups were not judged to be associated with the SAN Trimer exposure. The major finding was a dose-related peripheral neuropathy associated with the sciatic nerves in females and spinal nerve roots in males and females thereby suggesting that SAN trimer is potentially a nervous system toxicant. PMID:24060431

  7. Perinatal toxicity and carcinogenicity studies of styrene-acrylonitrile trimer, a ground water contaminant.

    Science.gov (United States)

    Behl, Mamta; Elmore, Susan A; Malarkey, David E; Hejtmancik, Milton R; Gerken, Diane K; Chhabra, Rajendra S

    2013-12-06

    Styrene acrylonitrile (SAN) trimer is a by-product in the production of acrylonitrile styrene plastics. Following a report of a childhood cancer cluster in the Toms River section of Dover Township, New Jersey, SAN Trimer was identified as one of the groundwater contaminants at Reich Farm Superfund site in the township. The contaminants from the Reich Farm site's ground water plume impacted two wells at the Parkway well field. The National Toxicology Program (NTP) studied the toxicity and carcinogenicity of SAN Trimer in rats exposed during their perinatal developmental period and adulthood. The chronic toxicity and carcinogenicity studies in F344/N rats were preceded by 7- and 18-week perinatal toxicity studies to determine the exposure concentrations for the 2-year studies. Subsequently, Fisher 344 pregnant dams were exposed to SAN Trimer containing diet at 400, 800, or 1600ppm concentrations during gestation, nursing and weaning periods of offspring followed by two year of adult exposures to both male and female pups. There was no statistically significant evidence of carcinogenic activity following SAN-Trimer exposure; however, rare neoplasms in the brain and spinal cord were observed in males and to lesser extent in female rats. These incidences were considered within the range of historical background in the animal model used in the current studies. Therefore, the presence of a few rarely occurring CNS tumors in the treated groups were not judged to be associated with the SAN Trimer exposure. The major finding was a dose-related peripheral neuropathy associated with the sciatic nerves in females and spinal nerve roots in males and females thereby suggesting that SAN Trimer is potentially a nervous system toxicant. Published by Elsevier Ireland Ltd.

  8. Microencapsulation of oleoresin from red ginger (Zingiber officinale var. Rubrum) in chitosan and alginate for fresh milk preservatives

    Science.gov (United States)

    Krisanti, Elsa; Astuty, Rizka Margi; Mulia, Kamarza

    2017-02-01

    The usage of red ginger rhizome (Zingiber officinale var. Rubrum) oleoresin extract as the preservative for fresh milk has not been studied yet. The aim of this research was to compare the inhibition effect of oleoresin extract-loaded chitosan-alginate microparticles, and various ginger-based preservatives added into fresh milk, on the growth of bacteria. The total count plate growth of bacteria after addition of the oleoresin-loaded chitosan-alginate microparticles was the lowest. In addition, the organoleptic test showed that this formulation had no significant effect on the color, taste, and flavor of fresh milk. The experimental results indicated that the oleoresin-loaded chitosan-alginate microparticles may effectively be used as a preservative for fresh milk.

  9. THE ADDED VALUE OF SHREDDED LELE AND PATIN CATFISH

    Directory of Open Access Journals (Sweden)

    Ristina Siti Sundari

    2017-09-01

    Full Text Available Fish is not only perishable product but also has segmented market. Consumption market such wants the fresh fish and certainty size. The problem is when the size of fish is too big for consumption, so that product is not wanted by consumer anymore. This research aimed at knowing the added value of shredded Lele and Patin catfish agribusiness and increasing prosperity of humanitarian society throughout processing the shredded catfishes. The data of this research was analyzed by Added Value Analysis of Hayami. The result showed that the shredded product of Lele catfish gave the added value IDR 14.295,00 per kilograms with the added value ratio was 25,53 percent and Conversion value was 0,35. Whereas, the shredded product of Patin catfish gave the added value IDR 18.295,00 per kilogram with the added value ratio was 29,04 percent and Conversion value was 0,35. The agribusiness toward processing and marketing of shredded Lele and Patin catfish was innovative agribusiness that could develop business opportunity so that it could move on the economical wheel and increasing humanitarian society prosperity actively. The market demand was still very wide either in town or out of town. The partnership among various not only government but also non government associations would be a good matter toward this agribusiness is running well.

  10. Black Hole Astrophysics in AdS Braneworlds

    CERN Document Server

    Emparan, R; Kaloper, Nemanja; Emparan, Roberto; Garcia-Bellido, Juan; Kaloper, Nemanja

    2003-01-01

    We consider astrophysics of large black holes localized on the brane in the infinite Randall-Sundrum model. Using their description in terms of a conformal field theory (CFT) coupled to gravity, deduced in Ref. [1], we show that they undergo a period of rapid decay via Hawking radiation of CFT modes. For example, a black hole of mass ${\\rm few} \\times M_\\odot$ would shed most of its mass in $\\sim 10^4 - 10^5$ years if the AdS radius is $L \\sim 10^{-1}$ mm, currently the upper bound from table-top experiments. Since this is within the mass range of X-ray binary systems containing a black hole, the evaporation enhanced by the hidden sector CFT modes could cause the disappearance of X-ray sources on the sky. This would be a striking signature of RS2 with a large AdS radius. Alternatively, for shorter AdS radii, the evaporation would be slower. In such cases, the persistence of X-ray binaries with black holes already implies an upper bound on the AdS radius of $L \\la 10^{-2}$ mm, an order of magnitude better than...

  11. Logarithmic AdS waves and Zwei-Dreibein gravity

    NARCIS (Netherlands)

    Bergshoeff, Eric A.; Goya, Andres F.; Merbis, Wout; Rosseel, Jan

    2014-01-01

    We show that the parameter space of Zwei-Dreibein Gravity (ZDG) in AdS(3) exhibits critical points, where massive graviton modes coincide with pure gauge modes and new 'logarithmic' modes appear, similar to what happens in New Massive Gravity. The existence of critical points is shown both at the

  12. Internet Advertising. Google AdWords versus Facebook Ads

    OpenAIRE

    Paul PAŞCU

    2014-01-01

    This article describes how to use the applications for Internet advertising, Google AdWords and Facebook Ads. Our attempt is to present the advantages and disadvantages of each of them, the costs and benefits, a useful aspect for companies that plan to start advertising campaigns on the Internet.

  13. Internet Advertising. Google AdWords versus Facebook Ads

    Directory of Open Access Journals (Sweden)

    Paul PAŞCU

    2014-05-01

    Full Text Available This article describes how to use the applications for Internet advertising, Google AdWords and Facebook Ads. Our attempt is to present the advantages and disadvantages of each of them, the costs and benefits, a useful aspect for companies that plan to start advertising campaigns on the Internet.

  14. 75 FR 62455 - Importation of Fresh Unshu Oranges From the Republic of Korea Into the Continental United States

    Science.gov (United States)

    2010-10-12

    ... sweet orange scab has been endemic in production areas, producers have been able to control the pest and... Health Inspection Service 7 CFR Part 319 RIN 0579-AD14 Importation of Fresh Unshu Oranges From the... fruit to remove certain restrictions on the importation of Unshu oranges from the Republic of Korea that...

  15. DISPERSION POLYMERIZATION OF STYRENE IN SUPERCRITICAL CARBON DIOXIDE UTILIZING RANDOM COPOLYMERS INCLUDING FLUORINATED ACRYLATE FOR PREPARING MICRON-SIZE POLYSTYRENE PARTICLES. (R826115)

    Science.gov (United States)

    The dispersion polymerization of styrene in supercritical CO2 utilizing CO2-philic random copolymers was investigated. The resulting high yield of polystyrene particles in the micron-size range was formed using various random copolymers as stabilizers. The p...

  16. Synthesis and characterization of poly(styrene-co-methyl methacrylate); Sintese e caracterizacao do poli(estireno-co-metacrilato de metila)

    Energy Technology Data Exchange (ETDEWEB)

    Augustinho, Tiago R.; Abarca, Silvia A.C.; Machado, Ricardo A.F. [Departamento de Engenharia Quimica e Alimentos - Universidade Federal de Santa Catarina - UFSC, Florianopolis, SC (Brazil)

    2011-07-01

    Polystyrene (PS) is nowadays commonly used due its advantages over competitors. PS presents a lower cost when compared with Acrylonitrile Butadiene Styrene (ABS) and with Polyethylene Tere-phthalate (PET), and can be easier processed than polypropylene (PP). At expandable form (EPS), can be used as projective equipment, thermal insulation, floating boards, refrigerators, isothermal, and low cost applications such as packaging and disposable material. Searching for more resistant materials and with a low cost, researches with copolymers materials are being developed. In this study, copolymerization reactions were carried out by suspension polymerization using monomers styrene and methyl methacrylate (MMA) with styrene. Styrene was in the highest percentage in relation to the MMA. The MMA was selected because is a monomer that presents a higher resistance than PS. The copolymerization was confirmed by performing infrared spectroscopy (IR), nuclear magnetic resonance of hydrogen (RMN{sup 1}H), differential scanning calorimetry (DSC) and thermogravimetry (TGA). (author)

  17. Studies on Superchilling of Fresh Skipjack

    Science.gov (United States)

    Matsuzaki, Yoh; Ogawa, Yutaka

    The freshness and meat colour of fresh skipjack can be retained only 2 or 3 days by ordinary cold storage. This paper deals with a new method, "suprchilling", which was developed by the authers, i. e., immediately after catch live skipjacks were immersed and killed instantly in NaCl brine at -10°C to -15°C for 30 to 40 minuites and thereafter in refrigerated sea water the center of the skipjack muscle was rapidly cooled to -0.5°C within 40 minuites. Form the results of apperance, organoleptic ratings, pH value, K value, metmyoglobin %, salt concentration and microscopic observation, "superchilling" could prolong the shelflife of skipjack 3 days longer than ordinary cold storage.

  18. Ultraviolet asymptotics for quasiperiodic AdS_4 perturbations

    CERN Document Server

    Craps, Ben; Jai-akson, Puttarak; Vanhoof, Joris

    2015-01-01

    Spherically symmetric perturbations in AdS-scalar field systems of small amplitude epsilon approximately periodic on time scales of order 1/epsilon^2 (in the sense that no significant transfer of energy between the AdS normal modes occurs) have played an important role in considerations of AdS stability. They are seen as anchors of stability islands where collapse of small perturbations to black holes does not occur. (This collapse, if it happens, typically develops on time scales of the order 1/epsilon^2.) We construct an analytic treatment of the frequency spectra of such quasiperiodic perturbations, paying special attention to the large frequency asymptotics. For the case of a self-interacting phi^4 scalar field in a non-dynamical AdS background, we arrive at a fairly complete analytic picture involving quasiperiodic spectra with an exponential suppression modulated by a power law at large mode numbers. For the case of dynamical gravity, the structure of the large frequency asymptotics is more complicated....

  19. Effects of chitosan-essential oil coatings on safety and quality of fresh blueberries.

    Science.gov (United States)

    Sun, Xiuxiu; Narciso, Jan; Wang, Zhe; Ference, Christopher; Bai, Jinhe; Zhou, Kequan

    2014-05-01

    Chitosan coating plus different essential oils was developed and applied to fresh blueberries in order to find more natural treatments to preserve fresh fruit quality and safety during postharvest storage. Studies were 1st performed in vitro where wild-type Escherichia coli and Penicillium digitatum were grown in suitable media, and then subjected to 6 essential oils. Three compounds, carvacrol (CAR), cinnamaldehyde (CIN), and trans-cinnamaldehyde (ECIN) had high antimicrobial capacity and were selected for an in vivo study for postharvest storage of blueberries. The selected essential oils, 0.5% each, were added into a chitosan solution and coated on fresh blueberries. After storage at 5, 10, and 20 °C for various days, fruit firmness and microbial populations were evaluated. The chitosan coating substantially decreased bacteria and yeasts/molds on the fruit, and all 3 essential oils added to the antimicrobial activities. Further dosage experiments showed that the antimicrobial activity remained even when lowering CAR concentration to 0.1% and ECIN to 0.2%. Chitosan, CAR, and ECIN also maintained fruit firmness. Our results suggest that chitosan coatings containing essential oils are effective in extending the shelf life of fresh blueberries. Blueberries are high-value fruit with strong antioxidant capacity and other health-promoting benefits. However, microbial food safety is an increasing concern, and decay and softening limits their storability. A combination of ≥ 0.1% CAR or ≥ 0.2% ECIN with a chitosan coating effectively reduced softening of fresh berries and decay by inhibiting microbial growth. © 2014 Institute of Food Technologists®

  20. Protonated Montmorillonite Maghnite-H+ Clay Used as Green Non-toxic Catalyst for the Synthesis of Biocompatible poly (DXL -co- Styrene.

    Directory of Open Access Journals (Sweden)

    N. HAMAM

    2016-06-01

    Full Text Available Copolymerization of 1,3-Dioxolane (DXL with Styrene (St catalyzed by Maghnite-H+ a montmorillonite sheet silicate clay exchanged with protons, was investigated. The cationic ring opening polymerization was initiated by Maghnite-H+ in bulk. The copolymer obtained was characterized by 1H-NMR, DSC and IR spectroscopy. The studies done, such as the effect of the amount of Maghnite-H+ on the syntheses of poly (DXL -co- Styrene.

  1. Microbiological Quality of Fresh Nopal Juice

    Directory of Open Access Journals (Sweden)

    Ana María Hernández-Anguiano

    2016-12-01

    Full Text Available The consumption of fresh nopal cactus juice is widely popular among health-conscious consumers in Mexico. The juice is prepared from fresh cladodes that have only been rinsed with tap water and are not subjected to a pasteurization or terminal bacterial reduction process. The aim of this study was to evaluate the microbial quality of commercially available fresh juices (n = 162 made with nopal in Texcoco, State of Mexico, during the summer and spring season. Standard microbiological methods, the PCR technique and the serological method were used for isolation and identification of bacteria. All samples contained total coliforms and 91% were positive for Escherichia coli. Although total coliforms and E. coli were detected throughout the study, their populations were significantly lower (p < 0.05 in winter and spring, respectively. Citrobacter youngae was found in 20% of the samples, an unidentified species of Citrobacter in 10%, C. freundii and Proteus mirabilis in 3%, and Salmonella Javiana in 1%. The presence of these microorganisms, especially Salmonella, in the nopal juices is unacceptable due to its health significance. The information generated in this study is relevant for human health risk assessment associated with the consumption of unpasteurized nopal juices and potential interventions to minimize pathogen contamination.

  2. Microbiological Quality of Fresh Nopal Juice

    Science.gov (United States)

    Hernández-Anguiano, Ana María; Landa-Salgado, Patricia; Eslava-Campos, Carlos Alberto; Vargas-Hernández, Mateo; Patel, Jitendra

    2016-01-01

    The consumption of fresh nopal cactus juice is widely popular among health-conscious consumers in Mexico. The juice is prepared from fresh cladodes that have only been rinsed with tap water and are not subjected to a pasteurization or terminal bacterial reduction process. The aim of this study was to evaluate the microbial quality of commercially available fresh juices (n = 162) made with nopal in Texcoco, State of Mexico, during the summer and spring season. Standard microbiological methods, the PCR technique and the serological method were used for isolation and identification of bacteria. All samples contained total coliforms and 91% were positive for Escherichia coli. Although total coliforms and E. coli were detected throughout the study, their populations were significantly lower (p < 0.05) in winter and spring, respectively. Citrobacter youngae was found in 20% of the samples, an unidentified species of Citrobacter in 10%, C. freundii and Proteus mirabilis in 3%, and Salmonella Javiana in 1%. The presence of these microorganisms, especially Salmonella, in the nopal juices is unacceptable due to its health significance. The information generated in this study is relevant for human health risk assessment associated with the consumption of unpasteurized nopal juices and potential interventions to minimize pathogen contamination. PMID:27973398

  3. Comparative Studies of two Fresh Water Snail Distributions and ...

    African Journals Online (AJOL)

    chemical properties of fresh water on snail hosts population. The methods in Water Engineering and Development Centre (WEDC) Analytical methods Manual were used in water analysis. Fresh water bodies namely: Kanye and Rimin Gado Dams ...

  4. AdS sub 2 supergravity and superconformal quantum mechanics

    CERN Document Server

    Astorino, M; Klemm, D; Zanon, D

    2003-01-01

    We investigate the asymptotic dynamics of topological anti-de Sitter supergravity in two dimensions. Starting from the formulation as a BF theory, it is shown that the AdS sub 2 boundary conditions imply that the asymptotic symmetries form a super-Virasoro algebra. Using the central charge of this algebra in Cardy's formula, we exactly reproduce the thermodynamical entropy of AdS sub 2 black holes. Furthermore, we show that the dynamics of the dilaton and its superpartner reduces to that of superconformal transformations that leave invariant one chiral component of the stress tensor supercurrent of a two-dimensional conformal field theory. This dynamics is governed by a supersymmetric extension of the de Alfaro-Fubini-Furlan model of conformal quantum mechanics. Finally, two-dimensional de Sitter gravity is also considered, and the dS sub 2 entropy is computed by counting CFT states.

  5. Entropy function and attractors for AdS black holes

    CERN Document Server

    Morales, J F; Morales, Jose F.; Samtleben, Henning

    2006-01-01

    We apply Sen's entropy formalism to the study of the near horizon geometry and the entropy of asymptotically AdS black holes in gauged supergravities. In particular, we consider non-supersymmetric electrically charged black holes with AdS_2 xS^{d-2} horizons in U(1)^4 and U(1)^3 gauged supergravities in d=4 and d=5 dimensions, respectively. We study several cases including static/rotating, BPS and non-BPS black holes in Einstein as well as in Gauss-Bonnet gravity. In all examples, the near horizon geometry and black hole entropy are derived by extremizing the entropy function and are given entirely in terms of the gauge coupling, the electric charges and the angular momentum of the black hole.

  6. AdS gravity and the scalar glueball spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Vento, Vicente [Departament de Fisica Teorica, Universitat de Valencia y Institut de Fisica Corpuscular, Consejo Superior de Investigaciones Cientificas, Burjassot (Valencia) (Spain)

    2017-09-15

    The scalar glueball spectrum has attracted much attention since the formulation of Quantum Chromodynamics. Different approaches give very different results for the glueball masses. We revisit the problem from the perspective of the AdS/CFT correspondence. (orig.)

  7. The Mixed Phase of Charged AdS Black Holes

    Directory of Open Access Journals (Sweden)

    Piyabut Burikham

    2016-01-01

    Full Text Available We study the mixed phase of charged AdS black hole and radiation when the total energy is fixed below the threshold to produce a stable charged black hole branch. The coexistence conditions for the charged AdS black hole and radiation are derived for the generic case when radiation particles carry charge. The phase diagram of the mixed phase is demonstrated for both fixed potential and charge ensemble. In the dual gauge picture, they correspond to the mixed phase of quark-gluon plasma (QGP and hadron gas in the fixed chemical potential and density ensemble, respectively. In the nuclei and heavy-ion collisions at intermediate energies, the mixed phase of exotic QGP and hadron gas could be produced. The mixed phase will condense and evaporate into the hadron gas as the fireball expands.

  8. National Meat Case Study 2004: Fresh product types and allocation of retail space.

    Science.gov (United States)

    Reicks, A L; Brooks, J C; Kelly, J M; Kuecker, W G; Boillot, K; Irion, R; Miller, M F

    2008-12-01

    Fresh meat retail cases in 104 supermarkets across 5 regions of the United States were audited for product space allocation, percentage of space allocated to each fresh meat category and frequency of species among all stock keeping units (n = 14,863). The United States was divided into Mountain/Southwest, Midwest, Northeast, Southeast, and West Coast regions. Fresh meat categories for self-service cases included beef muscle cuts, ground beef, pork, veal, lamb, chicken, turkey, fresh sausage, value-added, heat and serve, ham-bone-in, ham-boneless, ham steak, other processed meats, seafood, and nonmeat items. Fresh meat categories for the full-service case included seafood, beef, pork, chicken, and other. Whole muscle beef, pork, and chicken products were available in all stores. Ground beef products and turkey were reported in almost all stores, 94.5 to 100%, respectively. The majority of the self-service meat case was dedicated to beef in all regions except for the Northeast, where chicken occupied the majority of the self-service case. Linear meters of self-service fresh meat case were greatest in the Northeast region, which was similar to Mountain and Midwest regions, but different (P = 0.003) than the Southeast and West Coast regions. However, the West Coast region best utilized the retail meat case by providing consumers with the greatest number of offerings per linear meter. The percentage of stores audited with a full-service meat case was 37.5%, and the percentage with a full-service seafood case was 60.6%. The full-service meat case was the smallest (number of linear meters, P = 0.039) in the Southeast and largest (number of linear meters, P = 0.039) in the Midwest.

  9. Iron-Mediated ICAR ATRP of Styrene and Methyl Methacrylate in the Absence of Thermal Radical Initiator.

    Science.gov (United States)

    Zhang, Lifen; Miao, Jie; Cheng, Zhenping; Zhu, Xiulin

    2010-02-02

    Initiators for continuous activator regeneration in atom transfer radical polymerization (ICAR ATRP) is a new technique for conducting ATRP. ICAR ATRP has many strong advantages over normal ATRP, such as forming the reductive transition metal species in situ using oxidatively stable transition metal species and a lower amount of metal catalyst in comparison with the normal ATRP system. In this work, the iron-mediated ICAR ATRP of styrene and methyl methacrylate are reported for the first time using oxidatively stable FeCl(3)  · 6H(2) O as the catalyst in the absence of any thermal radical initiator. The kinetics of the polymerizations and effect of different polymerization conditions are studied. It is found that the polymerization of styrene can be conducted well even if the amount of iron(III) is as low as 50 ppm. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Production and characterization of poly(styrene-co-methylmethacrylate);Producao e caracterizacao de poliestireno-co-metacrilato de metila

    Energy Technology Data Exchange (ETDEWEB)

    Augustinho, Tiago R.; Coan, Thais; Abarca, Silvia A.C.; Testoni, Alex A.S.; Baumgarten, Bruno P.; Machado, Ricardo A.F., E-mail: tiagoqmc@gmail.co [Universidade Federal de Santa Catarina (UFSC), Florianopolis (Brazil). Dept. de Engenharia Quimica e Alimentos

    2009-07-01

    Polystyrene (PS) is a polymer used in diverse industrial segments. It is easy to process and has a low cost when compared to other materials. However, PS has low mechanical resistance, which limits its application in some areas. Thus, a methodology that is sufficiently used is the synthesis of a copolymer, formed of two or more monomers to get products that have characteristics that are not possible to obtain with only one monomer. In this work, the styrene and methyl methacrylate monomers had been carried through reactions of copolymerization by means of polymerization in suspension using (MMA) with styrene in a bigger percentage. MMA was selected for being a monomer that results in a polymeric configuration more resistant than the PS. The copolymerization was proven to occur by infra-red spectroscopy (IR) and Nuclear Magnetic Resonance (NMR). Different analyses were performed using different initiators, weight molar and conversion studies. (author)

  11. Copper mediated controlled radical copolymerization of styrene and2-ethylhexyl acrylate and determination of their reactivity ratios.

    Directory of Open Access Journals (Sweden)

    Bishnu Prasad Koiry

    2014-10-01

    Full Text Available Copolymerization is an important synthetic tool to prepare polymers with desirable combination of properties which are difficult to achieve from the different homopolymers concerned. This investigation reports the copolymerization of 2-ethylhexyl acrylate (EHA and styrene using copper bromide (CuBr as catalyst in combination with N,N,N’,N,N- pentamethyldiethylenetriamine (PMDETA as ligand and 1-phenylethyl bromide (PEBr as initiator. Linear kinetic plot and linear increase in molecular weights versus conversion indicate that copolymerization reactions were controlled. The copolymer composition was calculated using 1H NMR studies. The reactivity ratio of styrene and EHA (r1 and r2 were determined using the Finemann-Ross (FR, inverted Finemann-Ross (FR and Kelen-Tudos (KT methods. Thermal properties of the copolymers were also studied by using TGA and DSC analysis.

  12. SILAGE CANE SUGAR ADDED WITH DRIED BREWER

    Directory of Open Access Journals (Sweden)

    W. J. R. Castro

    2015-02-01

    Full Text Available The objective of this experiment was to evaluate the fermentative parameters and chemical composition of silage cane sugar added with residue dried brewery. The experimental design was completely randomized with four treatments and four replications: 100% cane sugar; 90% of cane sugar + 10% residue dried brewer; 80% of cane sugar + 20% residue dried brewer and 70% cane sugar + 30% dried brewer based on natural matter, composed silages. The sugar cane was chopped in a stationary machine with forage particle size of approximately 2 cm, and homogenized manually with the additives. For storage chopped fresh weight were used in experimental silos capacity of about 4 liters. The results showed that the contents of dry matter and crude protein showed positive linear (P0.05 with mean value of 3.81, while for ether extract and ash results were positive linear (P0.05 for N ammonia presented average value of 4.18. It is concluded that the addition of brewer dehydrated improves the fermentation process of silage cane sugar, in addition to improving their nutritional characteristics.

  13. Conserved higher-spin charges in AdS4

    Directory of Open Access Journals (Sweden)

    O.A. Gelfond

    2016-03-01

    Full Text Available Gauge invariant conserved conformal currents built from massless fields of all spins in 4d Minkowski space–time and AdS4 are described in the unfolded dynamics approach. The current cohomology associated with non-zero conserved charges is found. The resulting list of charges is shown to match the space of parameters of the conformal higher-spin symmetry algebra in four dimensions.

  14. Generalised structures for N=1 AdS backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Coimbra, André [Institut für Theoretische Physik & Center for Quantum Engineering and Spacetime Research,Leibniz Universität Hannover,Appelstraße 2, 30167 Hannover (Germany); Strickland-Constable, Charles [Institut de physique théorique, Université Paris Saclay, CEA, CNRS, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)

    2016-11-16

    We expand upon a claim made in a recent paper [http://arxiv.org/abs/1411.5721] that generic minimally supersymmetric AdS backgrounds of warped flux compactifications of Type II and M theory can be understood as satisfying a straightforward weak integrability condition in the language of E{sub d(d)}×ℝ{sup +} generalised geometry. Namely, they are spaces admitting a generalised G-structure set by the Killing spinor and with constant singlet generalised intrinsic torsion.

  15. ADS Bumblebee comes of age

    Science.gov (United States)

    Accomazzi, Alberto; Kurtz, Michael J.; Henneken, Edwin; Grant, Carolyn S.; Thompson, Donna M.; Chyla, Roman; McDonald, Steven; Shaulis, Taylor J.; Blanco-Cuaresma, Sergi; Shapurian, Golnaz; Hostetler, Timothy W.; Templeton, Matthew R.; Lockhart, Kelly E.

    2018-01-01

    The ADS Team has been working on a new system architecture and user interface named “ADS Bumblebee” since 2015. The new system presents many advantages over the traditional ADS interface and search engine (“ADS Classic”). A new, state of the art search engine features a number of new capabilities such as full-text search, advanced citation queries, filtering of results and scalable analytics for any search results. Its services are built on a cloud computing platform which can be easily scaled to match user demand. The Bumblebee user interface is a rich javascript application which leverages the features of the search engine and integrates a number of additional visualizations such as co-author and co-citation networks which provide a hierarchical view of research groups and research topics, respectively. Displays of paper analytics provide views of the basic article metrics (citations, reads, and age). All visualizations are interactive and provide ways to further refine search results. This new search system, which has been in beta for the past three years, has now matured to the point that it provides feature and content parity with ADS Classic, and has become the recommended way to access ADS content and services. Following a successful transition to Bumblebee, the use of ADS Classic will be discouraged starting in 2018 and phased out in 2019. You can access our new interface at https://ui.adsabs.harvard.edu

  16. The Network marketing of Fresh Agricultural Products in China

    OpenAIRE

    Yang, Xue

    2011-01-01

    The paper introduced the connotation of network marketing of fresh agricultural products and analyzed the fundaments of launching the C2C marketing of fresh agricultural products in China. The fundaments mainly cover the development of e-commerce, the transformation of consumption concept, the change of live style and the features of Chinese agricultural production. The developmental status of the C2C marketing of Chinese fresh vegetables and fresh fruits is introduced and the plights, includ...

  17. Ad skepticisms: Antecedents and consequences

    Directory of Open Access Journals (Sweden)

    Rafique Ahmed

    2016-11-01

    Full Text Available Engaging customer is the burning issue for companies especially the service sector, either online or offline. Minimizing the customer disengagement is the same like reducing dissatisfaction or churn. Customer disengagement may be caused by many factors, ad skepticism is one of them; ad skepticism has two main antecedents personality variable and consumption/influencing varia-bles. This research explores the relationship of ad skepticism with customer disengagement through personality variables which are cynicism, reactance and self-esteem. The unit of analysis is the telecom and banking industry of Pakistan which is foreseeing an era of virtual currency and both are customer oriented industries. Only offline disengagement is researched and data is collected from the Business centers of telecom and banking branches dealing with virtual curren-cy in Pakistan. Hypothetical model is given after digging the relevant literature; model is tested through confirmatory factor analysis and structural equation modeling. Eight hypotheses were purposed from the connections of model, all hypotheses are accepted except the cynicism posi-tive effect on social ad skepticism. This can be due to commonality of social and charity in Paki-stani society, Muslims consider charity as a pious act and they do not think for cynic behavior in charity or social related works. The results manifest that customers in telecom industry are hav-ing ad skepticism and that is becoming the cause of their disengagement. Further, social ad skep-ticism has more impact on the customer disengagement than the general ad skepticism. While the reactance has more effect on general ad skepticism than other antecedents and cynicism has the lowest impact on social ad skepticism than other antecedents.

  18. Surfactant and counter-ion distribution in styrene-butyl acrylate-acrylic acid dry latex submonolayers

    OpenAIRE

    Keslarek Amauri José; Leite Carlos Alberto P; Galembeck Fernando

    2004-01-01

    Styrene-butyl acrylate-acrylic acid latex submonolayers prepared using a non-reactive phosphate surfactant together with a reactive sulfonate surfactant were examined in a transmission microscope using electron energy loss spectroscopy imaging (ESI-TEM). Phosphorus is nearly absent from the particles core but it is detected in a thick shell and in unusual, strongly scattering structures with a low carbon content, and largely made out of inorganic phosphate. P is also dispersed outside the par...

  19. N-Heterocyclic carbene–palladium(II-1-methylimidazole complex catalyzed Mizoroki–Heck reaction of aryl chlorides with styrenes

    Directory of Open Access Journals (Sweden)

    Ting-Ting Gao

    2012-11-01

    Full Text Available A well-defined N-heterocyclic carbene–palladium(II-1-methylimidazole [NHC-Pd(II-Im] complex 1 was found to be an effective catalyst for the Mizoroki–Heck reaction of a variety of aryl chlorides with styrenes. Both activated and deactivated aryl chlorides work well to give the corresponding coupling products in good to excellent yields by using tetrabutylammonium bromide (TBAB as the ionic liquid.

  20. Effect of concentration and humidity on the formation of porous polymer films using Styrene Butadiene Co-Polymer

    Science.gov (United States)

    Jose, Renu; Sujith, A.; Predeep, P.

    2011-10-01

    Honeycomb structured porous materials from complex polymers are formed using water droplet templating method. In the present work microporous films were prepared from styrene butadiene rubber (SBR) using emulsion technique. The pore sizes can be easily tuned by changing the concentration and the humidity condition. The pore size is characterized by optical microscope and Scanning electron microscope (SEM). These films can be used for various applications in optoelectronics, photonics, catalysis, tissue engineering, bioanalytical purposes etc.

  1. Pyrolysis of waste electrical and electronic equipment: effect of antinomy trioxide on the pyrolysis of styrenic polymers.

    Science.gov (United States)

    Hall, W J; Bhaskar, T; Merpati, N M M; Muto, A; Sakata, Y; Williams, P T

    2007-09-01

    This work has investigated the effect that antimony trioxide has on the pyrolysis of styrenic polymers and the effect that different types of brominated flame retardants used in plastics have on the composition of the pyrolysis products. Brominated high impact polystyrene (Br-HIPS) which contained either 5% or 0% antimony trioxide and either decabromodiphenyl oxide (DDO) or decabromodiphenyl ethane (DDE) was pyrolysed in a fixed bed reactor at 430 degrees C. Some experiments on the fixed bed reactor involved mixing the Br-HIPS with polystyrene. The gaseous products were analysed by GC-FID and GC-TCD and it was found that antimony trioxide caused an increase in the proportion of ethane and ethene and suppressed the proportion of butane and butene. When DDE was the flame retardant increased proportions of ethane and ethene were found in the pyrolysis gas compared to when DDO used. When polystyrene was mixed with the Br-HIPS it suppressed the trends observed in the gas composition during the pyrolysis of Br-HIPS. The pyrolysis oils were characterised using FT-IR, GC-MS, GC-FID, and GC-ECD. It was found that the plastic which did not contain antimony trioxide pyrolysed to form mainly toluene, ethylbenzene, styrene, cumene, and alpha-methylstyrene. The oils produced from the pyrolysis of the plastic that contained antimony trioxide did not contain any styrene or alpha-methylstyrene, but instead contained greater concentrations of ethylbenzene and cumene. The absence of styrene and alpha-methylstyrene from the pyrolysis oil occurred even when the Br-HIPS was mixed with polystyrene. GC-ECD analysis of the oils showed that the plastics which did not contain antimony trioxide pyrolysed to form (1-bromoethyl)benzene, which was totally absent from the pyrolysis oils when antimony trioxide was present in the plastic.

  2. Bacterial adhesion to surfaces and microbial safety of fresh produce

    Science.gov (United States)

    Consumption of fresh produce is a central component of a healthy diet. However, contamination of fresh and fresh-cut fruits and vegetables such as leafy greens, tomatoes, cantaloupes is a source of ongoing concern for consumers. Growers, packers, processors and retailers work to control the incidenc...

  3. Simultaneous determination of styrene, toluene, and xylene metabolites in urine by gas chromatography/mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Szucs, Sandor; Toth, Laszlo; Sarvary, Attila; Adany, Roza [Debreceni Egyetem, Orvos- es Egeszsegtudomanyi Centrum, Nepegeszseguegyi Iskola, Megeloza Orvostani Intezet, Debrecen (Hungary); Legoza, Jozsef [Allami Nepegeszseguegyi es Tisztiorvosi Szolgalat Hajdu-Bihar Megyei Intezete, Debreceen (Hungary)

    2002-10-01

    Exposure to styrene, toluene, and xylene (STX) frequently occurs in various industrial settings leading to several adverse health effects. Therefore, the biological monitoring by determination of urinary mandelic acid (MA) and phenylglyoxylic acid (PGA), hippuric acid (HA), and 2-, 3-, and 4-methylhippuric acids (2-, 3-, and 4-MHAs), the metabolites of STX, is required or at least recommended in case of workers exposed by these agents. Considering the fact that co-exposure to STX frequently occurs, methods that have been described for the separate analysis of these compounds in urine samples cannot be used effectively for monitoring. Therefore, a reliable gas chromatographic/mass spectrometric (GC/MS) method was developed for the simultaneous identification and quantification of these metabolites. Following solid phase extraction of the urine samples, the extracts were silylated and analyzed by GC/MS using a HP-5MS capillary column. The method was evaluated for linearity, limits of detection and quantification, and specificity, as well as for precision, extraction efficiency, and stability at three different concentrations prepared in urine. The assay was linear up to 0.16 mg/ml for MA, and 0.32 mg/ml for PGA, HA, and 2-, 3- and 4-MHAs. The limits of detection and quantification of STX metabolites varied between 0.001 and 0.02 mg/ml, and from 0.01 to 0.04 mg/ml, respectively. The within-day and between-day precision, determined at low, medium, and high concentrations, ranged from 2 to 12% and 2 to 19%, respectively. The extraction efficiency was 70-80%. No degradation of the metabolites occurred in the urine samples under the possible working conditions. The method was applied for the analysis of the urine samples from exposed workers. The cost- and time-effectiveness, the technical advantages and validity parameters of this GC/MS analysis make it suitable for biological monitoring of mixed exposure to styrene, toluene and xylene. (orig.)

  4. What is a Fresh Scent in Perfumery? Perceptual Freshness is Correlated with Substantivity

    Directory of Open Access Journals (Sweden)

    Manuel Zarzo

    2012-12-01

    Full Text Available Perfumes are manufactured by mixing odorous materials with different volatilities. The parameter that measures the lasting property of a material when applied on the skin is called substantivity or tenacity. It is well known by perfumers that citrus and green notes are perceived as fresh and they tend to evaporate quickly, while odors most dissimilar to ‘fresh’ (e.g., oriental, powdery, erogenic and animalic scents are tenacious. However, studies aimed at quantifying the relationship between fresh odor quality and substantivity have not received much attention. In this work, perceptual olfactory ratings on a fresh scale, estimated in a previous study, were compared with substantivity parameters and antierogenic ratings from the literature. It was found that the correlation between fresh odor character and odorant substantivity is quite strong (r = −0.85. ‘Fresh’ is sometimes interpreted in perfumery as ‘cool’ and the opposite of ‘warm’. This association suggests that odor freshness might be somehow related to temperature. Assuming that odor perception space was shaped throughout evolution in temperate climates, results reported here are consistent with the hypothesis that ‘fresh’ evokes scents typically encountered in the cool season, while ‘warm’ would be evoked by odors found in nature during summer. This hypothesis is rather simplistic but it may provide a new insight to better understand the perceptual space of scents.

  5. Biofilm formation by staphylococci on fresh, fresh-frozen and processed human and bovine bone grafts.

    Science.gov (United States)

    Clauss, M; Tafin, U F; Bizzini, A; Trampuz, A; Ilchmann, T

    2013-01-30

    Biofilm formation is a multi-step process influenced by surface properties. We investigated early and mature biofilm of Staphylococcus aureus on 4 different biological calcium phosphate (CaP) bone grafts used for filling bone defects. We investigated standardised cylinders of fresh and fresh-frozen human bone grafts were harvested from femoral heads; processed humanand bovine bone grafts were obtained preformed. Biofilm formation was done in tryptic soy broth (TSB) using S. aureus (ATCC 29213) with static conditions. Biofilm density after 3 h (early biofilm) and 24 h (mature biofilm) was investigated by sonication and microcalorimetry. After 3 h, bacterial density was highest on fresh-frozenandfresh bone grafts. After 24 h, biofilm density was lowest on freshbone grafts (p  0.05). The lowest increase in bacterial density was detected on fresh bone grafts (p bone grafts showed minor structural differences in architecture but marked differences concerning serum coverage and the content of bone marrow, fibrous tissue and bone cells. These variations resulted in a decreased biofilm density on freshand fresh-frozenbone grafts after 24 h, despite an increased early biofilm formation and might also be responsible for the variations in colony morphology (small colonies). Detection of small colony variants by microcalorimetry might be a new approach to improve the understanding of biofilm formation.

  6. Influence of Poly(styrene-co-maleic acid) Copolymer Structure on the Properties and Self-Assembly of SMALP Nanodiscs.

    Science.gov (United States)

    Hall, Stephen C L; Tognoloni, Cecilia; Price, Gareth J; Klumperman, Bert; Edler, Karen J; Dafforn, Tim R; Arnold, Thomas

    2018-01-16

    Polymer stabilized nanodiscs are self-assembled structures composed of a polymer belt that wraps around a segment of lipid bilayer, and as such are capable of encapsulating membrane proteins directly from the cell membrane. To date, most studies on these nanodiscs have used poly(styrene-co-maleic acid) (SMA) with the term SMA-lipid particles (SMALPs) coined to describe them. In this study, we have determined the physical and thermodynamic properties of such nanodiscs made with two different SMA copolymers. These include a widely used and commercially available statistical poly(styrene-co-maleic acid) copolymer (coSMA) and a reversible addition-fragmentation chain transfer synthesized copolymer with narrow molecular weight distribution and alternating styrene and maleic acid groups with a polystyrene tail, (altSMA). We define phase diagrams for each polymer, and show that, regardless of polymer topological structure, self-assembly is driven by the free energy change associated with the polymers. We also show that nanodisc size is polymer dependent, but can be modified by varying polymer concentration. The thermal stability of each nanodisc type is similar, and both can effectively solubilize proteins from the E. coli membrane. These data show the potential for the development of different SMA polymers with controllable properties to produce nanodiscs that can be optimized for specific applications and will enable more optimized and widespread use of the SMA-based nanodiscs in membrane protein research.

  7. Formation of secondary aerosols from the ozonolysis of styrene: Effect of SO2 and H2O

    Science.gov (United States)

    Díaz-de-Mera, Yolanda; Aranda, Alfonso; Martínez, Ernesto; Rodríguez, Ana Angustias; Rodríguez, Diana; Rodríguez, Ana

    2017-12-01

    In this work we report the study of the ozonolysis of styrene and the reaction conditions leading to the formation of secondary aerosols. The reactions have been carried out in a Teflon chamber filled with synthetic air mixtures at atmospheric pressure and room temperature. We have found that the ozonolysis of styrene in the presence of low concentrations of SO2 readily produces new particles under concentrations of reactants lower than those required in experiments in the absence of SO2. Thus, nucleation events occur at concentrations around (5.6 ± 1.7) × 108molecule cm-3 (errors are 2σ±20%) and SO2 is consumed during the experiments. The reaction of the Criegee intermediates with SO2 to produce SO3 and then H2SO4 may explain (together with OH reactions' contribution) the high capacity of styrene to produce particulate matter in polluted atmospheres. The formation of secondary aerosols in the smog chamber is inhibited under high H2O concentrations. So, the potential formation of secondary aerosols under atmospheric conditions depends on the concentration of SO2 and relative humidity, with a water to SO2 rate constants ratio kH2O/kSO2 = (2.8 ± 0.7) × 10-5 (errors are 2σ±20%).

  8. A two-stage combined trickle bed reactor/biofilter for treatment of styrene/acetone vapor mixtures.

    Science.gov (United States)

    Vanek, Tomas; Halecky, Martin; Paca, Jan; Zapotocky, Lubos; Gelbicova, Tereza; Vadkertiova, Renata; Kozliak, Evguenii; Jones, Kim

    2015-01-01

    Performance of a two-stage biofiltration system was investigated for removal of styrene-acetone mixtures. High steady-state acetone loadings (above C(in)(Ac) = 0.5 g.m(-3) corresponding to the loadings > 34.5 g.m(-3).h(-1)) resulted in a significant inhibition of the system's performance in both acetone and styrene removal. This inhibition was shown to result from the acetone accumulation within the upstream trickle-bed bioreactor (TBR) circulating mineral medium, which was observed by direct chromatographic measurements. Placing a biofilter (BF) downstream to this TBR overcomes the inhibition as long as the biofilter has a sufficient bed height. A different kind of inhibition of styrene biodegradation was observed within the biofilter at very high acetone loadings (above C(in)(Ac) = 1.1 g.m(-3) or 76 g.m(-3).h(-1) loading). In addition to steady-state measurements, dynamic tests confirmed that the reactor overloading can be readily overcome, once the accumulated acetone in the TBR fluids is degraded. No sizable metabolite accumulation in the medium was observed for either TBR or BF. Analyses of the biodegradation activities of microbial isolates from the biofilm corroborated the trends observed for the two-stage biofiltration system, particularly the occurrence of an inhibition threshold by excess acetone.

  9. ADS/CFT and QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; de Teramond, Guy F.; /Costa Rica U. /SLAC

    2007-02-21

    The AdS/CFT correspondence between string theory in AdS space and conformal .eld theories in physical spacetime leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. Although QCD is not conformally invariant, one can nevertheless use the mathematical representation of the conformal group in five-dimensional anti-de Sitter space to construct a first approximation to the theory. The AdS/CFT correspondence also provides insights into the inherently non-perturbative aspects of QCD, such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space z and a specific impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. This connection allows one to compute the analytic form of the frame-independent light-front wavefunctions, the fundamental entities which encode hadron properties and allow the computation of decay constants, form factors, and other exclusive scattering amplitudes. New relativistic lightfront equations in ordinary space-time are found which reproduce the results obtained using the 5-dimensional theory. The effective light-front equations possess remarkable algebraic structures and integrability properties. Since they are complete and orthonormal, the AdS/CFT model wavefunctions can also be used as a basis for the diagonalization of the full light-front QCD Hamiltonian, thus systematically improving the AdS/CFT approximation.

  10. The controversy over the new star of AD.1408

    Science.gov (United States)

    Guangchao, Wang

    2015-08-01

    In recent years, the likelihood of a supernova occurring in AD 1408 has aroused a controversy in Chinese astronomy. The initial suggestion was made by Li Qi-bin, who discussed several Chinese records of temporary stars seen during the year and suggested that these records related to the same object- a supernova appearing in Cygnus. Stephenson considered that these records might be possible as a comet or meteor. Until now, the two sides still differ with each other over the question of these records. This article examines the controversy over the new star of AD 1408. Based on some fresh historical materials, this article partially support F. Richard Stephenson‘s pinpoint and put forward some ideas of identifying historical novae or supernovae.

  11. Maximal temperature of a gas in AdS spacetime

    Science.gov (United States)

    Dai, De-Chang; Stojkovic, Dejan

    2017-04-01

    Assuming only statistical mechanics and general relativity, we calculate the maximal temperature of gas of particles placed in anti-de Sitter (AdS) spacetime. If two particles with a given center of mass energy come close enough, according to classical gravity, they will form a black hole. We focus only on the black holes with a Hawking temperature lower than the environment, because they do not disappear. The number density of such black holes grows with the temperature in the system. At a certain finite temperature, the thermodynamical system will be dominated by black holes. This critical temperature is lower than the Planck temperature for the values of the AdS vacuum energy density below the Planck density. This result might be interesting from the AdS/CFT correspondence point of view, since it is different from the Hawking-Page phase transition, and it is not immediately clear what effect dynamically limits the maximal temperature of the thermal state on the CFT side of the correspondence.

  12. To transfer fresh or thawed embryos?

    DEFF Research Database (Denmark)

    Pinborg, Anja

    2012-01-01

    and multiple pregnancies, thereby increasing the safety for mother and child. Finally the article describes the accumulating literature on perinatal and long-term child outcome after transfer of frozen/thawed embryos, including a discussion on the concerns regarding cryo techniques and their possible roles...... and cons of FER versus fresh-embryo transfer with regard to both single-cycle and cumulative pregnancy and delivery rates. The review discusses the obvious advantages of FER: minimizing the proportion of pharmacological and surgical treatments, and lowering the risk of ovarian hyperstimulation syndrome...

  13. Analysis of acrylonitrile, 1,3-butadiene, and related compounds in acrylonitrile-butadiene-styrene copolymers for kitchen utensils and children's toys by headspace gas chromatography/mass spectrometry.

    Science.gov (United States)

    Ohno, Hiroyuki; Kawamura, Yoko

    2010-01-01

    A headspace gas chromatography/mass spectrometry method was developed for the simultaneous determination of the residual levels of acrylonitrile (AN), 1,3-butadiene (1,3-BD), and their related compounds containing propionitrile (PN) and 4-vinyl-1-cyclohexene (4-VC) in acrylonitrile-butadiene-styrene (ABS) copolymers for kitchen utensils and children's toys. A sample was cut into small pieces, then N,N-dimethylacetamide and an internal standard were added in a sealed headspace vial. The vial was incubated for 1 h at 90 degrees C and the headspace gas was analyzed by gas chromatography/mass spectrometry. The recovery rates of the analytes were 93.3-101.8% and the coefficients of variation were 0.3-6.5%. In ABS copolymers, the levels were 0.3-50.4 microg/g for AN, ND-4.5 microg/g for PN, 0.06-1.58 microg/g for 1,3-BD, and 1.1-295 microg/g for 4-VC. The highest level was found for 4-VC, which is a dimer of 1,3-BD, and the next highest was for AN, which is one of the monomers of the ABS copolymer. Furthermore, the method was also applied to acrylonitrile-styrene (AS) copolymers and polystyrenes (PS) for kitchen utensils, and nitrile-butadiene rubber (NBR) gloves. In AS copolymers, AN and PN were detected at 16.8-54.5 and 0.8-6.9 microg/g, respectively. On the other hand, the levels in PS and NBR samples were all low.

  14. Experimental acrylonitrile butadiene styrene and polyamide evisceration implant: a rabbit clinical and histopathology study

    Directory of Open Access Journals (Sweden)

    D.C. Gomes Júnior

    Full Text Available ABSTRACT The purpose of this study was to evaluate acrylonitrile butadiene styrene (ABS and polyamide implants in rabbits submitted to evisceration at the macroscopic and microstructure level and to assess clinical response and histopathological changes as well. For the experimental study implants of 12mm diameter were prepared by rapid prototyping, weighed and the outer and inner surfaces evaluated macroscopically and by electron microscopy. In addition, a compression test was performed and ultrastructural damage was then determined. After evisceration of the left eyeball, nine New Zealand rabbits received ABS implants and nine others received polyamide implants. The animals were assessed daily for 15 days after surgery and every seven days until the end of the study (90 days. Histopathological evaluation was performed at 15, 45 and 90 days after surgery. The ABS implants weighed approximately 0.44g, while the polyamide ones weighed 0.61g. Scanning electron microscopy demonstrated that the ABS implants had regular-sized, equidistant micropores, while the polyamide ones showed micropores of various sizes. The force required to fracture the ABS implant was 14.39 ±0.60 Mpa, while for the polyamide one, it was 16.80 ±1.05 Mpa. Fifteen days after surgery, we observed centripetal tissue infiltration and scarce inflammatory infiltrate. Implants may be used in the filling of anophthalmic cavities, because they are inert, biocompatible and allow tissue integration.

  15. Tensile, Creep, and Fatigue Behaviors of 3D-Printed Acrylonitrile Butadiene Styrene

    Science.gov (United States)

    Zhang, Hanyin; Cai, Linlin; Golub, Michael; Zhang, Yi; Yang, Xuehui; Schlarman, Kate; Zhang, Jing

    2018-01-01

    Acrylonitrile butadiene styrene (ABS) is a widely used thermoplastics in 3D printing. However, there is a lack of thorough investigation of the mechanical properties of 3D-printed ABS components, including orientation-dependent tensile strength and creep fatigue properties. In this work, a systematic characterization is conducted on the mechanical properties of 3D-printed ABS components. Specifically, the effect of printing orientation on the tensile and creep properties is investigated. The results show that, in tensile tests, the 0° printing orientation has the highest Young's modulus of 1.81 GPa, and ultimate strength of 224 MPa. In the creep test, the 90° printing orientation has the lowest k value of 0.2 in the plastics creep model, suggesting 90° is the most creep resistant direction. In the fatigue test, the average cycle number under load of 30 N is 3796 cycles. The average cycle number decreases to 128 cycles when the load is 60 N. Using the Paris law, with an estimated crack size of 0.75 mm, and stress intensity factor is varied from 352 to 700 N√ m, the derived fatigue crack growth rate is 0.0341 mm/cycle. This study provides important mechanical property data that is useful for applying 3D-printed ABS in engineering applications.

  16. Sulfonation of cPTFE Film grafted Styrene for Proton Exchange Membrane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Yohan Yohan

    2010-10-01

    Full Text Available Sulfonation of γ-ray iradiated and styrene-grafted crosslinked polytetrafluoroethylene film (cPTFE-g-S film have been done. The aim of the research is to make hydropyl membrane as proton exchange membrane fuel cell. Sulfonation was prepared with chlorosulfonic acid in chloroethane under various conditions. The impact of the percent of grafting, the concentration of chlorosulfonic acid, the reaction time,and the reaction temperature on the properties of sulfonated film is examinated. The results show that sulfonation of surface-grafted films is incomplete at room  temperature. The increasing of concentration of chlorosulfonic acid and reaction temperature accelerates the reaction but they also add favor side reactions. These will lead to decreasing of the ion-exchange capacity, water uptake, and proton conductivity but increasing the resistance to oxidation in a perhidrol solution. The cPTFE-g-SS membrane which is resulted has stability in a H2O2 30% solution for 20 hours.

  17. Tensile, Creep, and Fatigue Behaviors of 3D-Printed Acrylonitrile Butadiene Styrene

    Science.gov (United States)

    Zhang, Hanyin; Cai, Linlin; Golub, Michael; Zhang, Yi; Yang, Xuehui; Schlarman, Kate; Zhang, Jing

    2017-09-01

    Acrylonitrile butadiene styrene (ABS) is a widely used thermoplastics in 3D printing. However, there is a lack of thorough investigation of the mechanical properties of 3D-printed ABS components, including orientation-dependent tensile strength and creep fatigue properties. In this work, a systematic characterization is conducted on the mechanical properties of 3D-printed ABS components. Specifically, the effect of printing orientation on the tensile and creep properties is investigated. The results show that, in tensile tests, the 0° printing orientation has the highest Young's modulus of 1.81 GPa, and ultimate strength of 224 MPa. In the creep test, the 90° printing orientation has the lowest k value of 0.2 in the plastics creep model, suggesting 90° is the most creep resistant direction. In the fatigue test, the average cycle number under load of 30 N is 3796 cycles. The average cycle number decreases to 128 cycles when the load is 60 N. Using the Paris law, with an estimated crack size of 0.75 mm, and stress intensity factor is varied from 352 to 700 N√ m , the derived fatigue crack growth rate is 0.0341 mm/cycle. This study provides important mechanical property data that is useful for applying 3D-printed ABS in engineering applications.

  18. Estimation of the Surface Properties of Styrene-Acrylonitrile Random Copolymers from Contact Angle Measurements.

    Science.gov (United States)

    Adão; Saramago; Fernandes

    1999-09-01

    The surface free energy per unit area of a solid, gamma(S), is a fundamental property of materials and determines their surface and interfacial behavior in processes like wetting and adhesion. In this study the gamma(S) of a series of styrene-acrylonitrile random copolymers is evaluated. Three different approaches are used to determine the components in which the surface free energy can be decomposed. Using the geometric and the harmonic mean approach, the dispersive, gamma(d), and polar, gamma(p), components of the solid surface free energy were determined and compared to the Lifshitz-van der Waals, gamma(LW), and acid-base, gamma(AB), components using the approach developed by C. J. van Oss et al. (1987, Adv. Colloid Interface Sci. 28, 35). The acid-base approach was also used to evaluate the work of adhesion of the test liquids: water, glycerol, and thiodiglycol. It was found that the contact angles of these liquids follow closely the predictions of Cassie equation. The evaluation of the surface free energy components on one hand and the relative magnitude of the work of adhesion components on the other hand, suggest that below 50% of acrylonitrile the polystyrene repeating units are preferentially at the surface. Above 50% of acrylonitrile the segregation of the low-energy homopolymer at the surface decreases. Copyright 1999 Academic Press.

  19. Styrene-butadiene rubber/halloysite nanotubes nanocomposites modified by methacrylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Guo Baochun [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China)], E-mail: psbcguo@scut.edu.cn; Lei Yanda; Chen Feng; Liu Xiaoliang; Du Mingliang; Jia Demin [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2008-12-30

    Methacrylic acid (MAA) was used to improve the performance of styrene-butadiene rubber (SBR)/halloysite nanotubes (HNTs) nanocomposites by direct blending. The detailed interaction mechanisms of MAA and the in situ formed zinc methacrylate (ZDMA) were revealed by X-ray diffraction (XRD), surface area and porosity analysis, X-ray photoelectron spectroscopy (XPS) together with crosslink density determination. The strong interfacial bonding between HNTs and rubber matrix is resulted through ZDMA and MAA intermediated linkages. ZDMA connects SBR and HNTs via grafting/complexation mechanism. MAA bonds SBR and HNTs through grafting/hydrogen bonding mechanism. Significantly improved dispersion of HNTs in virtue of the interactions between HNTs and MAA or ZDMA was achieved. Effects of MAA content on the vulcanization behavior, morphology and mechanical properties of the nanocomposites were investigated. Promising mechanical properties of MAA modified SBR/HNTs nanocomposites were obtained. The changes in vulcanization behavior, mechanical properties and morphology were correlated with the interactions between HNTs and MAA or ZDMA and the largely improved dispersion of HNTs.

  20. Diphenylphosphino Styrene-Containing Homopolymers: Influence of Alkylation and Mobile Anions on Physical Properties.

    Science.gov (United States)

    Jangu, Chainika; Schultz, Alison R; Wall, Candace E; Esker, Alan R; Long, Timothy E

    2016-07-01

    Conventional free radical polymerization and post-alkylation of 4-diphenylphosphino styrene (DPPS) generate a new class of high-molecular-weight phosphonium-containing homopolymers with tunable thermal, viscoelastic, and wetting properties. Post-alkylation and subsequent anion exchange provide an effective method for tuning Tg values and thermal stability as a function of alkyl chain length and counteranion selection (X(-) , BF4 (-) , TfO(-) , and Tf2 N(-) ). Rheological characterization facilitates the generation of time-temperature-superposition (TTS) pseudomaster curves and subsequent analysis of frequency sweeps at various temperatures reveals two relaxation modes corresponding to long-range segmental motion and the onset of viscous flow. Contact angle measurements reveal the influence of counteranion selection on wetting properties, revealing increased contact angles for homopolymers containing nucleophilic counteranions. These investigations provide fundamental insight into phosphonium-containing polymers, aiming to guide future research and applications involving electro-active polymeric devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. About the cure kinetics in natural rubber/styrene Butadiene rubber blends at 433 K

    Energy Technology Data Exchange (ETDEWEB)

    Mansilla, M.A., E-mail: mmansilla@df.uba.ar [Laboratorio de Polimeros y Materiales Compuestos, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, C1428EGA Buenos Aires (Argentina); Marzocca, A.J. [Laboratorio de Polimeros y Materiales Compuestos, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, C1428EGA Buenos Aires (Argentina)

    2012-08-15

    Vulcanized blends of elastomers are employed in several goods mainly to improve physical properties and reduce costs. One of the most used blends of this kind is that composed by natural rubber (NR) and styrene butadiene rubber (SBR). The cure kinetic of these blends depends mainly on the compound formulation and the cure temperature and time. The preparation method of the blends can influence the mechanical properties of the vulcanized compounds. In this work the cure kinetic at 433 K of NR/SBR blends vulcanized with the system sulfur/TBBS (N-t-butyl-2-benzothiazole sulfenamide) is analyzed in samples prepared by mechanical mixing and solution blending. The two methods produce elastomer domains of NR and SBR, which present different microstructure due to the cure level attained during vulcanization. The cure kinetics is studied by means of rheometer tests and the model proposed by Kamal and Sourour. The analysis of the cure rate is presented and is related to the structure obtained during the vulcanization process.

  2. Devulcanization of styrene butadiene rubber by microwave energy: Effect of the presence of ionic liquid

    Directory of Open Access Journals (Sweden)

    S. Seghar

    2015-12-01

    Full Text Available In this study, styrene butadiene rubber (SBR was devulcanized using microwave irradiation. In particular, effect of ionic liquid (IL, pyrrolidinium hydrogen sulfate [Pyrr][HSO4], on the devulcanization performance was studied. It was observed that the evolution of the temperature reached by rubber powder exposed to microwave irradiation for different energy values was favored by the presence of ionic liquid [Pyrr][HSO4] significantly over the whole range of the microwave energy values. Beyond the threshold point of 220 Wh/kg, the soluble fraction after devulcanization sharply increased with increasing devulcanization microwave energy. For the powder mixed with [Pyrr][HSO4], the increase was more significant. Furthermore, the crosslink density was observed to decrease slowly with the microwave energy up to 220 Wh/kg, beyond which the crosslink density decreased significantly for the rubber impregnated with IL. For the rubber with IL, significant and continuous increase in Tg with microwave energy values was observed in comparison with the SBR where no change in transition temperature was observed. Mechanical shearing of rubber gums in the two-roll mill favored the devulcanization process, which indicated that the combination of mechanical loading with microwave energy and IL is an efficient procedure allowing an optimal devulcanization of rubbers.

  3. Application of Composite Powders Recycled from Graphite Tailings in Styrene-Butadiene Rubber

    Science.gov (United States)

    Hai, Yun; Liao, Libing; Lv, Guocheng; Qin, Faxiang; Mei, Lefu; Wei, Yaozu

    2015-11-01

    With styrene-butadiene rubber (SBR) as matrix and composite powders recycled from graphite tailings as fillers, the influence of the particle size and content of the composite powders on the tensile strength and electrical conductivity of the composite powder-filled SBR were studied. The results showed that composite powder recycled from graphite tailings could reinforce SBR, whose tensile strength was significantly increased with reducing the particle size of the composite powder, but it had little effect on the conductivity of the system. With composite powders as fillers in conjunction with conductive carbon black, the tensile strength and electrical conductivity of the system were greatly improved. The maximum tensile strength of the SBR filled with composite powder and conductive carbon black increased by 47% compared to that of the single composite powder-filled SBR. When the filling content of conductive carbon black was 10 phr and that of composite powder was above 30 phr, the volume resistivity of SBR showed a sharp decline, reaching a minimum about 106 Ω cm at 40 phr. All the results indicated that composite powder recycled from graphite tailings can be applied effectively as filler in SBR. It has great economic and environmental benefits.

  4. Carbon nanotube buckypaper reinforced acrylonitrile-butadiene-styrene composites for electronic applications.

    Science.gov (United States)

    Díez-Pascual, Ana M; Gascón, David

    2013-11-27

    Novel acrylonitrile-butadiene-styrene (ABS) nanocomposites reinforced with pristine or functionalized single- or multiwalled carbon nanotube buckypaper (BP) sheets were manufactured via hot-compression and vacuum infiltration. Their morphology, thermal, mechanical, and electrical properties were comparatively investigated. Scanning electron microscopy and thermogravimetric analysis showed that the infiltration process leads to better BP impregnation than the hot-press technique. BPs made from functionalized or short nanotubes form compact networks that hamper the penetration of the matrix chains, whereas those composed of pristine tubes possess large pores that facilitate the polymer flow, resulting in composites with low degree of porosity and improved mechanical performance. Enhanced thermal and electrical properties are found for samples incorporating functionalized BPs since dense networks lead to more conductive pathways, and a stronger barrier effect to the diffusion of degradation products, thus better thermal stability. According to dynamic mechanical analysis these composites exhibit the highest glass transition temperatures, suggesting enhanced filler-matrix interactions as corroborated by the Raman spectra. The results presented herein demonstrate that the composite performance can be tailored by controlling the BP architecture and offer useful insights into the structure-property relationships of these materials to be used in electronic applications, particularly for EMI shielding and packaging of integrated circuits.

  5. Olfactory loss in poly (acrylonitrile-butadiene-styrene) plastic injection-moulding workers.

    Science.gov (United States)

    Cheng, Shu-Fang; Chen, Mei-Lien; Hung, Po-Chen; Chen, Chiou-Jong; Mao, I-Fang

    2004-10-01

    Plastics manufacturing factories are the fifth largest category of factories in industrial estates in Taiwan. It is known that complex airborne compounds and pungent odours are emitted during plastic injection-moulding processes. Workers exposed to acrylonitrile-butadiene-styrene (ABS) thermal decomposition products (TDP) may have olfactory loss. This study examined olfactory loss in injection-moulding workers exposed to ABS TDP. The method recommended by the Connecticut Chemosensory Clinical Research Center (CCCRC) was used to test the olfactory function of subjects, including 1-butanol threshold and odour identification, both pre- and post-work. The study sample included 52 ABS plastic injection-moulding workers (exposed group), as well as 72 workers from other departments (reference group). The results revealed that the exposed group had lower olfactory function after work than the reference group. The decrease in olfactory function after 1 workday was statistically significant. The prevalence of abnormal olfactory function post-work in the exposed group was higher than in the reference group. The findings of this study implied the ABS plastic injection-moulding process may worsen olfactory function among workers. Notably, this effect decreased olfactory threshold scores, not odour identification scores.

  6. Crack initiation and propagation on the polymeric material ABS (Acrylonitrile Butadiene Styrene, under ultrasonic fatigue testing

    Directory of Open Access Journals (Sweden)

    G. M. Domínguez Almaraz

    2015-10-01

    Full Text Available Crack initiation and propagation have been investigated on the polymeric material ABS (Acrylonitrile Butadiene Styrene, under ultrasonic fatigue testing. Three controlled actions were implemented in order to carry out fatigue tests at very high frequency on this material of low thermal conductivity, they are: a The applying load was low to limit heat dissipation at the specimen neck section, b The dimensions of testing specimen were small (but fitting the resonance condition, in order to restraint the temperature gradient at the specimen narrow section, c Temperature at the specimen neck section was restrained by immersion in water or oil during ultrasonic fatigue testing. Experimental results are discussed on the basis of thermo-mechanical behaviour: the tail phenomenon at the initial stage of fatigue, initial shear yielding deformation, crazed development on the later stage, plastic strain on the fracture surface and the transition from low to high crack growth rate. In addition, a numerical analysis is developed to evaluate the J integral of energy dissipation and the stress intensity factor K, with the crack length

  7. Electromechanical properties of poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) films.

    Science.gov (United States)

    Okuzaki, Hidenori; Suzuki, Hiroki; Ito, Takamichi

    2009-08-20

    Free-standing films made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrene sulfonate) (PEDOT/PSS) were prepared by casting water dispersion of its colloidal particles. Morphology, water vapor sorption, and electro-active polymer actuating behavior of the resulting films were investigated by means of atomic force microscopy, sorption isotherm, thermal mechanical analysis, and electromechanical analysis. It was found that the PEDOT/PSS film sorbed 60% of moisture at relative water vapor pressure of 0.95. Upon application of 10 V, the film underwent contraction of 2.4% in air at 50% relative humidity (RH) which significantly increased to 4.5% at 90% RH. The principle lay in desorption of water vapor sorbed in the film due to Joule heating, where electric field was capable of controlling the equilibrium of water vapor sorption. The film generated contractile stress as high as 17 MPa under isometric conditions and work capacity attained 174 kJ m(-3), where Young's modulus of the film increased from 1.8 to 2.6 GPa by application of 6 V at 50% RH.

  8. Surface modification of carbon black for the reinforcement of polycarbonate/acrylonitrile–butadiene–styrene blends

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, B.B. [School of Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); Chen, Y. [School of materials Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002 (China); Wang, F. [School of Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); Hong, R.Y., E-mail: rhong@suda.edu.cn [School of Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); College of Chemistry, Chemical Engineering and Materials Science & Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China)

    2015-10-01

    Highlights: • CB was modified through the method of oxygen plasma treatment. • Surface modified CB applied in PC/ABS blends. • The treated CB showed better compatibility in PC/ABS blends. • PC/ABS blends with treated CB showed better mechanical and thermal properties. - Abstract: The surface of carbon black was modified by oxygen plasma treatment for different times (10, 20 and 30 min). In order to increase the applicability of carbon black (CB), functional groups were grafted on the generally inert surface of CB using oxygen plasma. The surface compositional and structural changes that occurred on CB were investigated by SEM, FT-IR, Raman spectroscopy, XRD and BET. Subsequently, CB reinforced polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) composites were prepared by internal batch mixing with the addition of different content of CB (3, 6, 9, 12 wt%). The morphology of PC/ABS/CB (7/3/6 wt%) nanocomposites was studied through scanning electron microscopy. Observations of SEM images showed that the plasma-treated CB had a better dispersion in the blend matrix. Moreover, the mechanical tests showed that the tensile strength and impact strength were improved by 32.4% and 22.5%, respectively, with the addition of plasma-treated CB. In addition, the thermal stability was improved and glass transition temperatures of both PC and ABS increased as shown by TGA and DSC, respectively.

  9. Styrene-butadiene rubber/halloysite nanotubes nanocomposites modified by sorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Guo Baochun, E-mail: psbcguo@scut.edu.cn [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China); Chen Feng; Lei Yanda; Liu Xiaoliang; Wan Jingjing; Jia Demin [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2009-05-30

    Sorbic acid (SA) was used to improve the performance of styrene-butadiene rubber (SBR)/halloysite nanotubes (HNTs) nanocomposites by direct blending. The detailed mechanisms for the largely improved performance were studied by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), porosity analysis and crosslink density determination. The strong interfacial bonding between HNTs and rubber matrix is resulted through SA intermediated linkages. SA bonds SBR and HNTs through grafting copolymerization/hydrogen bonding mechanism. Significantly improved dispersion of HNTs in virtue of the interactions between HNTs and SA was achieved. Formation of zinc disorbate (ZDS) was revealed during the vulcanization of the composites. However, in the present systems, the contribution of ZDS to the reinforcement was limited. Effects of SA content on the vulcanization behavior, morphology and mechanical properties of the nanocomposites were investigated. Promising mechanical properties of SA modified SBR/HNTs nanocomposites were obtained. The changes in vulcanization behavior, mechanical properties and morphology were correlated with the interactions between HNTs and SA and the largely improved dispersion of HNTs.

  10. Styrene-butadiene rubber/halloysite nanotubes nanocomposites modified by sorbic acid

    Science.gov (United States)

    Guo, Baochun; Chen, Feng; Lei, Yanda; Liu, Xiaoliang; Wan, Jingjing; Jia, Demin

    2009-05-01

    Sorbic acid (SA) was used to improve the performance of styrene-butadiene rubber (SBR)/halloysite nanotubes (HNTs) nanocomposites by direct blending. The detailed mechanisms for the largely improved performance were studied by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), porosity analysis and crosslink density determination. The strong interfacial bonding between HNTs and rubber matrix is resulted through SA intermediated linkages. SA bonds SBR and HNTs through grafting copolymerization/hydrogen bonding mechanism. Significantly improved dispersion of HNTs in virtue of the interactions between HNTs and SA was achieved. Formation of zinc disorbate (ZDS) was revealed during the vulcanization of the composites. However, in the present systems, the contribution of ZDS to the reinforcement was limited. Effects of SA content on the vulcanization behavior, morphology and mechanical properties of the nanocomposites were investigated. Promising mechanical properties of SA modified SBR/HNTs nanocomposites were obtained. The changes in vulcanization behavior, mechanical properties and morphology were correlated with the interactions between HNTs and SA and the largely improved dispersion of HNTs.

  11. Evaluation of Styrene-Divinylbenzene Beads as a Support to Immobilize Lipases

    Directory of Open Access Journals (Sweden)

    Cristina Garcia-Galan

    2014-06-01

    Full Text Available A commercial and very hydrophobic styrene-divinylbenzene matrix, MCI GEL® CHP20P, has been compared to octyl-Sepharose® beads as support to immobilize three different enzymes: lipases from Thermomyces lanuginosus (TLL and from Rhizomucor miehie (RML and Lecitase® Ultra, a commercial artificial phospholipase. The immobilization mechanism on both supports was similar: interfacial activation of the enzymes versus the hydrophobic surface of the supports. Immobilization rate and loading capacity is much higher using MCI GEL® CHP20P compared to octyl-Sepharose® (87.2 mg protein/g of support using TLL, 310 mg/g using RML and 180 mg/g using Lecitase® Ultra. The thermal stability of all new preparations is much lower than that of the standard octyl-Sepharose® immobilized preparations, while the opposite occurs when the inactivations were performed in the presence of organic co-solvents. Regarding the hydrolytic activities, the results were strongly dependent on the substrate and pH of measurement. Octyl-Sepharose® immobilized enzymes were more active versus p-NPB than the enzymes immobilized on MCI GEL® CHP20P, while RML became 700-fold less active versus methyl phenylacetate. Thus, the immobilization of a lipase on this matrix needs to be empirically evaluated, since it may present very positive effects in some cases while in other cases it may have very negative ones.

  12. Reversed preparation of low-density poly(divinylbenzene/styrene) foam columns coated with gold films

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Yinhai; Wang, Ni; Li, Yaling; Yao, Mengqi; Gan, Haibo; Hu, Wencheng, E-mail: huwc@uestc.edu.cn

    2016-06-15

    Highlights: • A reversed fabrication of low density foam columns coated with gold films was proposed. • The uniformity in thickness and purity of gold film are easy to be controlled. • A compact layer is prepared through an electrophoretic deposition method. • A low density (12 mg/cc) foam column coated with gold film is obtained. - Abstract: This work aims to fabricate low-density, porous, non-conductive, structural poly(divinylbenzene/styrene) foam columns by high-internal-phase emulsion templating. We prepare these non-conductive foam columns coated with a thin gold layer by electrochemical deposition and the reversed preparation technique. As expected, the density of the foam obtained through this novel method was about 12 mg cm{sup −3}, and the thickness of the gold coating was about 3 μm. We performed field emission scanning electron microscopy to morphologically and microstructurally characterize the products and X-ray diffraction and energy dispersive spectroscopy to determine the composition of the gold coating.

  13. Catalytic combustion of styrene over copper based catalyst: inhibitory effect of water vapor.

    Science.gov (United States)

    Pan, Hongyan; Xu, Mingyao; Li, Zhong; Huang, Sisi; He, Chun

    2009-07-01

    The effects of water vapor on the activity of the copper based catalysts with different supports such as CuO/gamma-Al2O3, CuO/SiO2 and CuO/TiO2 for styrene combustion were investigated. The catalytic activity of the catalysts was tested in the absence of and presence of water vapor and the catalysts were characterized. Temperature programmed desorption (TPD) experiments and diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) measurements were conducted in order to estimate and explain the water effects. Results showed that the existence of water vapor had a significant negative effect on the catalytic activity of these copper based catalysts due to the competition adsorption of water molecule. DRIFTS studies showed that the catalyst CuO/gamma-Al2O3 had the strongest adsorption of water, while the catalyst CuO/TiO2 had the weakest adsorption of water. H2O-TPD studies also indicated that the order of desorption activation energies of water vapor on the catalysts or the strength of interactions of water molecules with the surfaces of the catalysts was CuO/gamma-Al2O3>CuO/SiO2>CuO/TiO2. As a consequence of that, the CuO/TiO2 exhibited the better durability to water vapor, while CuO/gamma-Al2O3 had the poorest durability to water vapor among these three catalysts.

  14. Acrylonitrile Butadiene Styrene (ABS) plastic based low cost tissue equivalent phantom for verification dosimetry in IMRT.

    Science.gov (United States)

    Kumar, Rajesh; Sharma, S D; Deshpande, Sudesh; Ghadi, Yogesh; Shaiju, V S; Amols, H I; Mayya, Y S

    2009-12-17

    A novel IMRT phantom was designed and fabricated using Acrylonitrile Butadiene Styrene (ABS) plastic. Physical properties of ABS plastic related to radiation interaction and dosimetry were compared with commonly available phantom materials for dose measurements in radiotherapy. The ABS IMRT phantom has provisions to hold various types of detectors such as ion chambers, radiographic/radiochromic films, TLDs, MOSFETs, and gel dosimeters. The measurements related to pre-treatment dose verification in IMRT of carcinoma prostate were carried out using ABS and Scanditronics-Wellhoffer RW3 IMRT phantoms for five different cases. Point dose data were acquired using ionization chamber and TLD discs while Gafchromic EBT and radiographic EDR2 films were used for generating 2-D dose distributions. Treatment planning system (TPS) calculated and measured doses in ABS plastic and RW3 IMRT phantom were in agreement within +/-2%. The dose values at a point in a given patient acquired using ABS and RW3 phantoms were found comparable within 1%. Fluence maps and dose distributions of these patients generated by TPS and measured in ABS IMRT phantom were also found comparable both numerically and spatially. This study indicates that ABS plastic IMRT phantom is a tissue equivalent phantom and dosimetrically it is similar to solid/plastic water IMRT phantoms. Though this material is demonstrated for IMRT dose verification but it can be used as a tissue equivalent phantom material for other dosimetry purposes in radiotherapy.

  15. Method for the separation of high impact polystyrene (HIPS) and acrylonitrile butadiene styrene (ABS) plastics

    Science.gov (United States)

    Jody, Bassam J.; Arman, Bayram; Karvelas, Dimitrios E.; Pomykala, Jr., Joseph A.; Daniels, Edward J.

    1997-01-01

    An improved method is provided for separating acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS) plastics from each other. The ABS and HIPS plastics are shredded to provide a selected particle size. The shredded particles of the ABS and HIPS plastics are applied to a solution having a solution density in a predefined range between 1.055 gm/cm.sup.3 and 1.07 gm/cm.sup.3, a predefined surface tension in a range between 22 dynes/cm to 40 dynes/cm and a pH in the range of 1.77 and 2.05. In accordance with a feature of the invention, the novel method is provided for separating ABS and HIPS, two solid thermoplastics which have similar densities by selectively modifying the effective density of the HIPS using a binary solution with the appropriate properties, such as pH, density and surface tension, such as a solution of acetic acid and water or a quaternary solution having the appropriate density, surface tension, and pH.

  16. Bond Characteristics of Macro Polypropylene Fiber in Cementitious Composites Containing Nanosilica and Styrene Butadiene Latex Polymer

    Directory of Open Access Journals (Sweden)

    Jae-Woong Han

    2015-01-01

    Full Text Available This study evaluated the bond properties of polypropylene (PP fiber in plain cementitious composites (PCCs and styrene butadiene latex polymer cementitious composites (LCCs at different nanosilica contents. The bond tests were evaluated according to JCI SF-8, in which the contents of nanosilica in the cement were 0, 2, 4, 6, 8, and 10 wt%, based on cement weight. The addition of nanosilica significantly affected the bond properties between macro PP fiber and cementitious composites. For PCCs, the addition of 0–2 wt% nanosilica enhanced bond strength and interface toughness, whereas the addition of 4 wt% or more reduced bond strength and interface toughness. The bond strength and interfacial toughness of LCCs also increased with the addition of up to 6% nanosilica. The analysis of the relative bond strength showed that the addition of nanosilica affects the bond properties of both PCC and LCC. This result was confirmed via microstructural analysis of the macro PP fiber surface after the bond tests, which revealed an increase in scratches due to frictional forces and fiber tearing.

  17. Nickel ion removal using nanoporous poly(styrene-co divinyl benzene) copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Bagherian, Abbas; Ghorbani, Mohsen; Mirzababaei, Seyed Nima [Babol University of Technology, Babol (Iran, Islamic Republic of)

    2015-10-15

    To achieve a suitable porous structure and high mechanical strength that is extremely valuable properties in adsorbent polymeric particles, poly(styrene-co-divinylbenzene) with high amounts of cross-linker and diverse proportions of diluent agent (porogen) were synthesized according to the methodology of the suspension polymerization technique. The structural characteristics of the particles and their adsorption properties for adsorption of Nickel ions were studied. Effect of solvent type and monomeric fraction on particles morphology and porosity was discussed. The solvents including n-heptane (HEP) and acetonitrile and monomer fraction was 50% and 30% of divinylbenzene (DVB). From the results obtained, we decided to apply an adsorbent with high mechanical strength and a porous structure appropriate for absorbing the Ni(II). The copolymer was characterized by Fourier transform infrared (FT-IR) analysis. We used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) tests to study the morphology and particle size of the nanoparticles. According to the results, the copolymers synthesized with n-heptane have more porosity. Also an increase in the percentage of DVB caused finer pores. After synthesis of copolymer the applicability of these polymer beads to separation and concentration of Ni(II) is discussed. In separation of Ni(II) from aqueous solution, the effects of pH, temperature and time are discussed and thermodynamic and kinetic calculations are done and its isotherm are fitted with various equations.

  18. Fermionic currents in AdS spacetime with compact dimensions

    Science.gov (United States)

    Bellucci, S.; Saharian, A. A.; Vardanyan, V.

    2017-09-01

    We derive a closed expression for the vacuum expectation value (VEV) of the fermionic current density in a (D +1 )-dimensional locally AdS spacetime with an arbitrary number of toroidally compactified Poincaré spatial dimensions and in the presence of a constant gauge field. The latter can be formally interpreted in terms of a magnetic flux treading the compact dimensions. In the compact subspace, the field operator obeys quasiperiodicity conditions with arbitrary phases. The VEV of the charge density is zero and the current density has nonzero components along the compact dimensions only. They are periodic functions of the magnetic flux with the period equal to the flux quantum and tend to zero on the AdS boundary. Near the horizon, the effect of the background gravitational field is small and the leading term in the corresponding asymptotic expansion coincides with the VEV for a massless field in the locally Minkowski bulk. Unlike the Minkowskian case, in the system consisting of an equal number of fermionic and scalar degrees of freedom, with same masses, charges and phases in the periodicity conditions, the total current density does not vanish. In these systems, the leading divergences in the scalar and fermionic contributions on the horizon are canceled and, as a consequence of that, the charge flux, integrated over the coordinate perpendicular to the AdS boundary, becomes finite. We show that in odd spacetime dimensions the fermionic fields realizing two inequivalent representations of the Clifford algebra and having equal phases in the periodicity conditions give the same contribution to the VEV of the current density. Combining the contributions from these fields, the current density in odd-dimensional C -,P - and T -symmetric models are obtained. As an application, we consider the ground state current density in curved carbon nanotubes described in terms of a (2 +1 )-dimensional effective Dirac model.

  19. New Features in ADS Labs

    Science.gov (United States)

    Accomazzi, Alberto; Kurtz, M. J.; Henneken, E. A.; Grant, C. S.; Thompson, D.; Di Milia, G.; Luker, J.; Murray, S. S.

    2013-01-01

    The NASA Astrophysics Data System (ADS) has been working hard on updating its services and interfaces to better support our community's research needs. ADS Labs is a new interface built on the old tried-and-true ADS Abstract Databases, so all of ADS's content is available through it. In this presentation we highlight the new features that have been developed in ADS Labs over the last year: new recommendations, metrics, a citation tool and enhanced fulltext search. ADS Labs has long been providing article-level recommendations based on keyword similarity, co-readership and co-citation analysis of its corpus. We have now introduced personal recommendations, which provide a list of articles to be considered based on a individual user's readership history. A new metrics interface provides a summary of the basic impact indicators for a list of records. These include the total and normalized number of papers, citations, reads, and downloads. Also included are some of the popular indices such as the h, g and i10 index. The citation helper tool allows one to submit a set of records and obtain a list of top 10 papers which cite and/or are cited by papers in the original list (but which are not in it). The process closely resembles the network approach of establishing "friends of friends" via an analysis of the citation network. The full-text search service now covers more than 2.5 million documents, including all the major astronomy journals, as well as physics journals published by Springer, Elsevier, the American Physical Society, the American Geophysical Union, and all of the arXiv eprints. The full-text search interface interface allows users and librarians to dig deep and find words or phrases in the body of the indexed articles. ADS Labs is available at http://adslabs.org

  20. Entanglement entropy and duality in AdS4

    Directory of Open Access Journals (Sweden)

    Ioannis Bakas

    2015-07-01

    Full Text Available Small variations of the entanglement entropy δS and the expectation value of the modular Hamiltonian δE are computed holographically for circular entangling curves in the boundary of AdS4, using gravitational perturbations with general boundary conditions in spherical coordinates. Agreement with the first law of thermodynamics, δS=δE, requires that the line element of the entangling curve remains constant. In this context, we also find a manifestation of electric–magnetic duality for the entanglement entropy and the corresponding modular Hamiltonian, following from the holographic energy–momentum/Cotton tensor duality.

  1. Fermionic continuous spin gauge field in (AdS space

    Directory of Open Access Journals (Sweden)

    R.R. Metsaev

    2017-10-01

    Full Text Available Fermionic continuous spin field propagating in (AdS space–time is studied. Gauge invariant Lagrangian formulation for such fermionic field is developed. Lagrangian of the fermionic continuous spin field is constructed in terms of triple gamma-traceless tensor–spinor Dirac fields, while gauge symmetries are realized by using gamma-traceless gauge transformation parameters. It is demonstrated that partition function of fermionic continuous spin field is equal to one. Modified de Donder gauge condition that considerably simplifies analysis of equations of motion is found. Decoupling limits leading to arbitrary spin massless, partial-massless, and massive fermionic fields are studied.

  2. Surfactant-Free RAFT Emulsion Polymerization of Styrene Using Thermoresponsive macroRAFT Agents: Towards Smart Well-Defined Block Copolymers with High Molecular Weights

    Directory of Open Access Journals (Sweden)

    Steffen Eggers

    2017-12-01

    Full Text Available The combination of reversible addition–fragmentation chain transfer (RAFT and emulsion polymerization has recently attracted much attention as a synthetic tool for high-molecular-weight block copolymers and their micellar nano-objects. Up to recently, though, the use of thermoresponsive polymers as both macroRAFT agents and latex stabilizers was impossible in aqueous media due to their hydrophobicity at the usually high polymerization temperatures. In this work, we present a straightforward surfactant-free RAFT emulsion polymerization to obtain thermoresponsive styrenic block copolymers with molecular weights of around 100 kDa and their well-defined latexes. The stability of the aqueous latexes is achieved by adding 20 vol % of the cosolvent 1,4-dioxane (DOX, increasing the phase transition temperature (PTT of the used thermoresponsive poly(N-acryloylpyrrolidine (PAPy macroRAFT agents above the polymerization temperature. Furthermore, this cosolvent approach is combined with the use of poly(N,N-dimethylacrylamide-block-poly(N-acryloylpiperidine-co-N-acryloylpyrrolidine (PDMA-b-P(APi-co-APy as the macroRAFT agent owning a short stabilizing PDMA end block and a widely adjustable PTT of the P(APi-co-APy block in between 4 and 47 °C. The temperature-induced collapse of the latter under emulsion polymerization conditions leads to the formation of RAFT nanoreactors, which allows for a very fast chain growth of the polystyrene (PS block. In dynamic light scattering (DLS, as well as cryo-transmission electron microscopy (cryoTEM, moreover, all created latexes indeed reveal a high (temperature stability and a reversible collapse of the thermoresponsive coronal block upon heating. Hence, this paper pioneers a versatile way towards amphiphilic thermoresponsive high-molecular-weight block copolymers and their nano-objects with tailored corona switchability.

  3. Improvement in the etching performance of the acrylonitrile-butadiene-styrene resin by MnO2-H3PO4-H2SO4 colloid.

    Science.gov (United States)

    Zhao, Wenxia; Ding, Jie; Wang, Zenglin

    2013-05-21

    The present study aimed to evaluate the surface etching of the acrylonitrile-butadiene-styrene (ABS) resin in the MnO2-H3PO4-H2SO4 colloid. To enhance the soluble Mn(IV) ion concentration and improve the etching performance of ABS resin, H3PO4 was added as a complexing agent into the MnO2-H2SO4 etching system. The effects of the H2SO4 concentration and etching time on the surface topography, surface roughness, adhesion strength, and the surface chemistry of the ABS substrates were investigated. The optimal oxidation potentials of MnO2 in the colloids decreased from 1.426 to 1.369 V with the addition of H3PO4. Though the etching conditions changed from 70 °C for 20 min to 60 °C for 10 min, the adhesion strength between the ABS substrates and electroless copper film increased from 1.19 to 1.33 KN/m after etching treatment. This could be attributed to the significant increase of the soluble Mn(IV) ion concentration in the MnO2-H3PO4-H2SO4 colloid. The surface chemistry results demonstrated that the oxidation reaction of -C═C- bonds in the polybutadiene phase was accelerated in the etching process by the addition of H3PO4, and the abundant -COOH and -OH groups were formed rapidly on the ABS surface with the etching treatment. These results were in agreement with the results of surface scanning electron microscopic observations and adhesion strength measurement. The results suggested that the MnO2-H3PO4-H2SO4 colloid was an effective surface etching system for the ABS surface roughness.

  4. Introducing ADS 2.0

    Science.gov (United States)

    Accomazzi, Alberto; Kurtz, M. J.; Henneken, E. A.; Grant, C. S.; Thompson, D.; Luker, J.; Chyla, R.; Murray, S. S.

    2014-01-01

    In the spring of 1993, the Smithsonian/NASA Astrophysics Data System (ADS) first launched its bibliographic search system. It was known then as the ADS Abstract Service, a component of the larger Astrophysics Data System effort which had developed an interoperable data system now seen as a precursor of the Virtual Observatory. As a result of the massive technological and sociological changes in the field of scholarly communication, the ADS is now completing the most ambitious technological upgrade in its twenty-year history. Code-named ADS 2.0, the new system features: an IT platform built on web and digital library standards; a new, extensible, industrial strength search engine; a public API with various access control capabilities; a set of applications supporting search, export, visualization, analysis; a collaborative, open source development model; and enhanced indexing of content which includes the full-text of astronomy and physics publications. The changes in the ADS platform affect all aspects of the system and its operations, including: the process through which data and metadata are harvested, curated and indexed; the interface and paradigm used for searching the database; and the follow-up analysis capabilities available to the users. This poster describes the choices behind the technical overhaul of the system, the technology stack used, and the opportunities which the upgrade is providing us with, namely gains in productivity and enhancements in our system capabilities.

  5. Antifungal Edible Coatings for Fresh Citrus Fruit: A Review

    Directory of Open Access Journals (Sweden)

    Lluís Palou

    2015-12-01

    Full Text Available According to their origin, major postharvest losses of citrus fruit are caused by weight loss, fungal diseases, physiological disorders, and quarantine pests. Cold storage and postharvest treatments with conventional chemical fungicides, synthetic waxes, or combinations of them are commonly used to minimize postharvest losses. However, the repeated application of these treatments has led to important problems such as health and environmental issues associated with fungicide residues or waxes containing ammoniacal compounds, or the proliferation of resistant pathogenic fungal strains. There is, therefore, an increasing need to find non-polluting alternatives to be used as part of integrated disease management (IDM programs for preservation of fresh citrus fruit. Among them, the development of novel natural edible films and coatings with antimicrobial properties is a technological challenge for the industry and a very active research field worldwide. Chitosan and other edible coatings formulated by adding antifungal agents to composite emulsions based on polysaccharides or proteins and lipids are reviewed in this article. The most important antifungal ingredients are selected for their ability to control major citrus postharvest diseases like green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, and include low-toxicity or natural chemicals such as food additives, generally recognized as safe (GRAS compounds, plant extracts, or essential oils, and biological control agents such as some antagonistic strains of yeasts or bacteria.

  6. Rainfall Distribution and the Possibility for Healthy and Fresh Drinking Water

    Directory of Open Access Journals (Sweden)

    Alif Noor Anna

    2014-12-01

    Full Text Available The information of rain water quality in Indonesia is rarely recorded, where as it is important for the region in which the source of fresh water is unavailable. Rain water composition is mostly ascertained by water vapour and ions which are available in the atmosphere during vapouration. In fact the rain water composition of coast region is sea water like and rain water chemical composition of urban are then become HNO3 and HSO4, while rain water of active vulcanic region eventuality has a high sulphur-wombed so that its quality sulphuric-acid. For the region in which the source of fresh water is unavailable the rain water is previously sterilized. Sterilization is consecutively done by adding salts, killing all bacteria, spores, and filltering.

  7. Improving the quality of fresh-cut apples, pears, and melons using natural additives.

    Science.gov (United States)

    Alandes, L; Quiles, A; Pérez-Munuera, I; Hernando, I

    2009-03-01

    Improving the quality of different fresh-cut fruits by adding natural substances was studied. "Fuji" apples, "Flor de Invierno" pears, and "Piel de Sapo" melons were treated with calcium lactate, N-acetyl-L-cysteine, glutathione, and malic acid and stored for 4 wk at 4 degrees C. Instrumental texture (penetration), microstructure (light microscopy), acidity, soluble solids, color, pectinmethylesterase activity, and microflora were studied. The results showed that the combined treatment reinforced the cell walls strengthening the structure and texture of these fruits and maintained the L* and a* values throughout 4 wk of storage at 4 degrees C. The combination of additives provided low microbial counts in apples until the 4th week and in melons until the 2nd week. So, this combined treatment could be used to extend the shelf life of some fresh-cut fruits while preserving their quality.

  8. Food Preference of Fresh-Water Invertebrates - Comparing Fresh and Decomposed Angiosperm and a Filamentous Alga

    NARCIS (Netherlands)

    Kornijow, R.; Gulati, R.D.; Ozimek, T.

    1995-01-01

    1. Fresh and decomposed Mougeotia sp. (a filamentous green alga) and Elodea nuttallii (a vascular plant) were offered as food to three species of aquatic macroinvertebrates (Lymnnea peregra, Asellus meridianus and Endochironomus albipennis) to test: (i) if filamentous algae are preferred to aquatic

  9. AdS nonlinear instability: moving beyond spherical symmetry

    Science.gov (United States)

    Dias, Óscar J. C.; Santos, Jorge E.

    2016-12-01

    Anti-de Sitter (AdS) is conjectured to be nonlinear unstable to a weakly turbulent mechanism that develops a cascade towards high frequencies, leading to black hole formation (Dafermos and Holzegel 2006 Seminar at DAMTP (University of Cambridge) available at https://dpmms.cam.ac.uk/~md384/ADSinstability.pdf, Bizon and Rostworowski 2011 Phys. Rev. Lett. 107 031102). We give evidence that the gravitational sector of perturbations behaves differently from the scalar one studied by Bizon and Rostworowski. In contrast with Bizon and Rostworowski, we find that not all gravitational normal modes of AdS can be nonlinearly extended into periodic horizonless smooth solutions of the Einstein equation. In particular, we show that even seeds with a single normal mode can develop secular resonances, unlike the spherically symmetric scalar field collapse studied by Bizon and Rostworowski. Moreover, if the seed has two normal modes, more than one resonance can be generated at third order, unlike the spherical collapse of Bizon and Rostworowski. We also show that weak turbulent perturbative theory predicts the existence of direct and inverse cascades, with the former dominating the latter for equal energy two-mode seeds.

  10. AdS pure spinor superstring in constant backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Chandia, Osvaldo [Departamento de Ciencias, Facultad de Artes Liberales, Universidad Adolfo Ibáñez,Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez,Diagonal Las Torres 2640, Peñalolén, Santiago (Chile); Bevilaqua, L. Ibiapina [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte,Caixa Postal 1524, 59072-970, Natal, RN (Brazil); Vallilo, Brenno Carlini [Facultad de Ciencias Exactas, Departamento de Ciencias Físicas, Universidad Andres Bello,Republica 220, Santiago (Chile)

    2014-06-05

    In this paper we study the pure spinor formulation of the superstring in AdS{sub 5}×S{sup 5} around point particle solutions of the classical equations of motion. As a particular example we quantize the pure spinor string in the BMN background.

  11. Numerical Simulations of Asymptotically AdS Spacetimes

    Science.gov (United States)

    Bantilan, Hans

    In this dissertation, we introduce a numerical scheme to construct asymptotically anti-de Sitter spacetimes with Lorentzian signature, focusing on cases that preserve five-dimensional axisymmetry. We study the field theories that are dual to these spacetimes by appealing to the AdS/CFT correspondence in the regime where the gravity dual is completely described by Einstein gravity. The numerical scheme is based on generalized harmonic evolution, and we begin by obtaining initial data defined on some Cauchy hypersurface. For the study described in this dissertation, we use a scalar field to source deviations from pure AdS5, and obtain data that correspond to highly deformed black holes. We evolve this initial data forward in time, and follow the subsequent ringdown. What is novel about this study is that the initial horizon geometry cannot be considered a small perturbation of the final static horizon, and hence we are probing an initial non-linear phase of the evolution of the bulk spacetime. On the boundary, we find that the dual CFT stress tensor behaves like that of a thermalized N = 4 SYM fluid. We find that the equation of state of this fluid is consistent with conformal invariance, and that its transport coefficients match those previously calculated for an N = 4 SYM fluid via holographic methods. Modulo a brief transient that is numerical in nature, this matching appears to hold from the initial time onwards. We transform these solutions computed in global AdS onto a Minkowski piece of the boundary, and examine the temperature of the corresponding fluid flows. Under this transformation, the spatial profile of temperature at the initial time resembles a Lorentz-flattened pancake centered at the origin of Minkowski space. By interpreting the direction along which the data is flattened as the beam-line direction, our initial data can be thought of as approximating a head-on heavy ion collision at its moment of impact.

  12. Smooth causal patches for AdS black holes

    Science.gov (United States)

    Raju, Suvrat

    2017-06-01

    We review the paradox of low energy excitations of a black hole in anti-de Sitter space (AdS). An appropriately chosen unitary operator in the boundary theory can create a locally strong excitation near the black hole horizon, whose global energy is small as a result of the gravitational redshift. The paradox is that this seems to violate a general rule of statistical mechanics, which states that an operator with energy parametrically smaller than k T cannot create a significant excitation in a thermal system. When we carefully examine the position dependence of the boundary unitary operator that produces the excitation and the bulk observable necessary to detect the anomalously large effect, we find that they do not both fit in a single causal patch. This follows from a remarkable property of position-space AdS correlators that we establish explicitly and resolves the paradox in a generic state of the system, since no combination of observers can both create the excitation and observe its effect. As a special case of our analysis, we show how this resolves the "Born rule" paradox of Marolf and Polchinski [J. High Energy Phys. 01 (2016) 008, 10.1007/JHEP01(2016)008] and we verify our solution using an independent calculation. We then consider boundary states that are finely tuned to display a spontaneous excitation outside the causal patch of the infalling observer, and we propose a version of causal patch complementarity in AdS/CFT that resolves the paradox for such states as well.

  13. ADS-B in space

    DEFF Research Database (Denmark)

    Knudsen, Bjarke Gosvig; Jensen, Morten; Birklykke, Alex

    2014-01-01

    them to the terrestrial receivers. This paper gives an overview of the GATOSS mission and of its highly-sensitive ADS-B software-defined radio receiver payload. Details of the design and implementation of the receiver's decoder are introduced. The first real-life, space-based results show that ADS......-B signals are indeed successfully received in space and retransmitted to a terrestrial station by the GATOSS nano-satellite orbiting at 700+ km altitudes, thus showing that GATOSS is capable of tracking flights, including transoceanic ones, from space....

  14. Development of hand-held nondestructive detection device for assessing meat freshness

    Science.gov (United States)

    Wei, Wensong; Peng, Yankun; Qiao, Lu

    2016-05-01

    Meat freshness is directly related to the health of consumers, and total volatile basic nitrogen (TVB-N) content is an important reference index for evaluating pork freshness. This paper attempted to measure TVB-N content for assessing pork meat freshness using a new self-developed portable and low cost detection device designed by ourselves basing on near infrared technique. The front-end part of this device was an integrated detection component containing a mini probe which was about 5cm in diameter circle. In the signal acquiring component, silicon photodiode detector was embedded in the center of light source in probe and spectral response range was 400-1100nm to receive diffuse light from pork meat surface in mini probe. The main circuits in this device included stabilized current supply circuit which was used to provide a stable power supply for each LED light source in probe and signal processing circuit which was utilized to complete signal amplification and A/D conversion, In addition, another vital function of the signal processing circuit was to analysis detection signals from mini probe in the detection component. For verifying this device performance, 58 pork samples with different freshness attributes and Multiple Linear Regression (MLR) mathematical method and ratio data processing algorithm were employed to build pork TVB-N content prediction model, and comparing with results from raw data model, the correlation coefficient of prediction and validation of TVB-N were 0.8027 and 0.7291 respectively, and the accuracy of predicting pork freshness was about 78.6%. This work demonstrates that it has the potential in nondestructive detection of TVB-N content in pork meat using this device, which can simplify related instruments design structure and reduce their development cost in future.

  15. Use of powdered egg yolk vs fresh egg yolk for the cryopreservation of ovine semen.

    Science.gov (United States)

    Marco-Jiménez, F; Puchades, S; Mocé, E; Viudes-de-Cartro, M P; Vicente, J S; Rodriguez, M

    2004-12-01

    Egg yolk is a common additive to sperm cryopreservation diluents. Because of its animal origin, however, it also represents a potential risk of microbiological contamination in the diluent. This potential contamination can be avoided by using powdered egg yolk, instead of fresh egg yolk, as it is pasteurized. This study was conducted to determine ram sperm cryosurvival was affected by the type of egg yolk used (powdered egg yolk or fresh egg yolk) and by yolk concentration (10, 15 or 20%) in the diluent. Microbiological analyses were also performed to quantify the microbiological contamination in the diluents containing the two types of egg yolk. Sperm cryosurvival was determined by motility and morphology analyses after thawing. Motility parameters were assessed using a computer-assisted sperm analysis (CASA) system, and the percentage of sperm with a normal apical ridge was evaluated using a differential interference contrast microscope. No significant differences were observed between diluents in the percentage of sperm with normal apical ridge. However, higher percentages of total motile cells were observed for samples containing powdered egg yolk (69%) compared to samples containing fresh egg yolk (60%). However, sperm in diluents containing fresh egg yolk, exhibited higher values for average-path velocity, straight-line velocity and beat cross frequency and lower values for amplitude of lateral head displacement (p diluents containing powdered egg yolk. Microbiological contamination was similar (diluents, and no bacterial growth was observed in either, when antibiotics were added. Therefore, powdered egg yolk can be effective used in diluents for the freezing of ram semen. However, the in vivo fertility of sperm frozen in diluents containing powdered egg yolk should be tested, as some motility parameters were different for sperm treated with powdered egg yolk compared to fresh egg yolk.

  16. Preparation and Structural Analysis of Nano-Silver Loaded Poly(styrene-co-acrylic acid) Core-Shell Nanospheres with Defined Shape and Composition.

    Science.gov (United States)

    Zhang, Jin; Zhao, Xiaoyu; Wang, Yanfei; Zhu, Liang; Yang, Libin; Li, Gang; Sha, Zuoliang

    2017-08-23

    A systematic study for the preparation and structural analysis of poly(styrene- co -acrylic acid) composite nanospheres (PSA) and silver nanoparticles loaded poly(styrene- co -acrylic acid) composite nanospheres (nAg@PSA) is reported. Poly(styrene- co -acrylic acid) nanospheres were synthesized by soap-free emulsion polymerization of styrene (St) and acrylic acid (AA) in water. Ag nanoparticles (Ag-NPs) were well-dispersed on the surfaces of poly(styrene- co -acrylic acid) composite nanospheres by in situ chemical reduction of AgNO₃ using NaBH₄ as a reducing agent in water. The particle size of PSA nanospheres was uniform. The surfaces of PSA nanospheres were distributed by highly uniform half-sphere arrays. Those half-sphere protruded more with the increase of the feeding amount of AA or the feed ratios of AA and St. The carboxyl groups content of nanospheres was directly proportional to the nanosphere surface area. This relationship and X-ray photoelectron spectroscopy and transmission electron microscopy images of the PSA nanospheres indicate that the acrylic acid was mainly distributed on the surface of the polystyrene spheres with unnegligible thickness. The number of Ag-NPs depends on immobilized carboxyl groups on the surface of PSA, according to thermogravimetry, ultraviolet-visible, X-ray diffraction and transmission electron microscopy results.

  17. Evaluation of the Parameters and Conditions of Process in the Ethylbenzene Dehydrogenation with Application of Permselective Membranes to Enhance Styrene Yield

    Directory of Open Access Journals (Sweden)

    Paulo Jardel P. Araújo

    2016-01-01

    Full Text Available Styrene is an important monomer in the manufacture of thermoplastic. Most of it is produced by the catalytic dehydrogenation of ethylbenzene. In this process that depends on reversible reactions, the yield is usually limited by the establishment of thermodynamic equilibrium in the reactor. The styrene yield can be increased by using a hybrid process, with reaction and separation simultaneously. It is proposed using permselective composite membrane to remove hydrogen and thus suppress the reverse and secondary reactions. This paper describes the simulation of a dehydrogenation process carried out in a tubular fixed-bed reactor wrapped in a permselective composite membrane. A mathematical model was developed, incorporating the various mass transport mechanisms found in each of the membrane layers and in the catalytic fixed bed. The effects of the reactor feed conditions (temperature, steam-to-oil ratio, and the weight hourly space velocity, the fixed-bed geometry (length, diameter, and volume, and the membrane geometry (thickness of the layers on the styrene yield were analyzed. These variables were used to determine experimental conditions that favour the production of styrene. The simulation showed that an increase of 40.98% in the styrene yield, compared to a conventional fixed-bed process, could be obtained by wrapping the reactor in a permselective composite membrane.

  18. Verification of average daily maximum permissible concentration of styrene in the atmospheric air of settlements under the results of epidemiological studies of the children’s population

    Directory of Open Access Journals (Sweden)

    М.А. Zemlyanova

    2015-03-01

    Full Text Available We presented the materials on the verification of the average daily maximum permissible concentration of styrene in the atmospheric air of settlements performed under the results of own in-depth epidemiological studies of children’s population according to the principles of the international risk assessment practice. It was established that children in the age of 4–7 years when exposed to styrene at the level above 1.2 of threshold level value for continuous exposure develop the negative exposure effects in the form of disorders of hormonal regulation, pigmentary exchange, antioxidative activity, cytolysis, immune reactivity and cytogenetic disbalance which contribute to the increased morbidity of diseases of the central nervous system, endocrine system, respiratory organs, digestion and skin. Based on the proved cause-and-effect relationships between the biomarkers of negative effects and styrene concentration in blood it was demonstrated that the benchmark styrene concentration in blood is 0.002 mg/dm3. The justified value complies with and confirms the average daily styrene concentration in the air of settlements at the level of 0.002 mg/m3 accepted in Russia which provides the safety for the health of population (1 threshold level value for continuous exposure.

  19. Co-polymerization of methyl methacrylate and styrene via surfactant-free emulsion polymerization, as a potential material for photonic crystal application

    Science.gov (United States)

    Kassim, Syara; Zahari, Siti Balqis; Tahrin, Rabiatul Addawiyah Azwa; Harun, Noor Aniza

    2017-09-01

    Photonic crystals are being the great interest of researcher to studies due to a variety of potential application for the interaction of light including the solar cells, optical sensors and paints. In order to evaluate the fabrication of photonic crystals thin film, a free-emulsifier emulsion copolymerization of styrene and methyl methacrylate was carried out. By using the self -assembly approach, this method offers the opportunity to produce crystalline polymer sphere in more ease operation, low cost and environmental friendly. The influences of the mixing ratio of monomer and amount of initiators were studied. In advance, the presence of styrene as co-monomer had improved the thermal degradation of polymer methyl methacrylate. While in changing the mixing ratio of styrene and methyl methacrylate resulted in particle size of the sphere. The size of polymer particles slightly increased on increasing volume of styrene monomer ratio. This occurred because the properties of styrene in water where it sparingly soluble and lead to coagulation of particles. This simple, yet effective method for preparing functional complex 3D structures has the potential to be used generically to fabricate a variety of functional porous 3D structures that could find application not only in new or improved photonic crystal (PC) devices but also in areas such as catalysis, solar cell, separation, fuel cells technology, microelectronics and optoelectronics.

  20. Chitosan/polyanion surface modification of styrene–butadiene–styrene block copolymer membrane for wound dressing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jen Ming, E-mail: jmyang@mail.cgu.edu.tw [Department of Chemical and Materials Engineering, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Yang, Jhe-Hao [Department of Electronic Engineering, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Huang, Huei Tsz [Department of Chemical and Materials Engineering, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan (China)

    2014-01-01

    The surface of styrene–butadiene–styrene block copolymer (SBS) membrane is modified with tri-steps in this study. At first, two step modified SBS membrane (MSBS) was prepared with epoxidation and ring opening reaction with maleated ionomer. Then chitosan was used as the polycation electrolyte and sodium alginate, poly(γ-glutamic acid) (PGA) and poly(aspartic acid) (PAsp) were selected as polyanion electrolytes to deposit on the surfaces of MSBS membrane by the layer-by-layer self-assembly (LbL) deposition technique to get three [chitosan/polyanion] LbL modified SBS membranes, ([CS/Alg], [CS/PGA] and [CS/PAsp]). From the quantitative XPS analysis and water contact angle measurement, it is found that the order of wettability and the content of functional group percentages of COO{sup −} and -O=C-N- on the three [CS/polyanion] systems are [CS/Alg] > [CS/PGA] > [CS/PAsp]. Performances of water vapor transmission rates, fibronectin adsorption, antibacterial assessment and 3T3 fibroblast cell growth on [CS/Alg], [CS/PGA] and [CS/PAsp] membranes were also evaluated. With the evaluation of water vapor transmission rate, these [CS/Alg], [CS/PGA] and [CS/PAsp] membranes are sterile semipermeable with water evaporation at about 82 ± 8 g/day · m{sup 2}. It is found that the amount of fibronectin adsorption on the three [CS/polyanion] systems is significantly determined by the sum of the functional group of COO{sup −} and -O=C-N- on the surfaces of [CS/Alg], [CS/PGA] and [CS/PAsp] systems. The results are inverse with the sum of the functional group of COO{sup −} and -O=C-N- on the three [CS/polyanion]. From the cytotoxicity test and cell adhesion and proliferation assay of 3T3 fibroblasts on the three [CS/polyanion] systems, it revealed that the cells not only remained viable but they also proliferated on the surfaces of [CS/Alg], [CS/PGA] and [CS/PAsp]. The bactericidal activity was found on [CS/Alg], [CS/PGA] and [CS/PAsp]. The transport of bacterial through

  1. Haemophilia home infusions with dried fresh plasma.

    Science.gov (United States)

    Lurie, A; Oberwaldner, B; Shapiro, M

    1975-05-31

    A group of 26 haemophilic patients was successfully managed on a home infusion programme over a one-year period. Single donor units of dried fresh plasma, the coagulant activity of which was adequate to ensure haemostasis of most of the haemorrhagic episodes treated, were used. The transmission of hepatitis was kept to a minimum by careful selection of regular, known donors and by the utilisation of single donor units of plasma in preference to plasma pools. Although the programme was costly, it was less expensive than it would have been had alternate antihaemophilic products been used. The advantages and disadvantages of self-administration are discussed. No serious mishaps occurred, and the programme was considered an outstanding success by both laymen and medical personnel. Minor alterations in liver function tests were demonstrated in several of the recipients. No factor VIII inhibitors were detected.

  2. Fresh perspectives for a better world

    CERN Multimedia

    Danielle Amy Venton

    While it’s no surprise that technology has the ability to change the world, it sometimes changes it in surprising ways. The Citizen Cyberscience Centre project is promoting change for humanitarian causes through distributed volunteer initiatives, such as volunteer computing and ‘volunteer thinking’. The inaugural lecture of a planned series was held at CERN in late October. The United Nations Institute for Training and Research (UNITAR), the University of Geneva (UNIGE), and CERN have recently set up a new partnership and launched a lecture series, which will invite experts in the humanities and technologies to share fresh perspectives on ways to work for a better world. The inaugural lecture at CERN was given by two speakers, Mo Ibrahim and Alpheus Bingham, each of them behind initiatives using technology to address difficult problems. Mo Ibrahim founded Celtel International, one of Africa’s most successful mobile network operators. Ibrahim’s company has ...

  3. [Microbial indicators and fresh water quality assessment].

    Science.gov (United States)

    Briancesco, Rossella

    2005-01-01

    Traditionally, the microbiological quality of waters has been measured by the analysis of indicator microorganisms. The article reviews the sanitary significance of traditional indicators of faecal contamination (total coliforms, faecal coliforms and faecal streptococci) and points out their limits. For some characteristics Escherichia coli may be considered a more useful indicator then faecal coliforms and recently it has been included in all recent laws regarding fresh, marine and drinking water. A clearer taxonomic definition of faecal streptococci evidenced the difficulty into defining a specific standard methodology of enumeration and suggested the more suitable role of enterococci as indicator microorganisms. Several current laws require the detection of enterococci. The resistance of Clostridium perfringens spores may mean that they would serve as a useful indicator of the sanitary quality of sea sediments.

  4. Distribution of water in fresh cod

    DEFF Research Database (Denmark)

    Andersen, Charlotte Møller; Rinnan, A.

    2002-01-01

    can he explained by the smaller muscle cells and muscle fibers in the tail, which may influence the distributions of water into the different pools. The amount of one of the water populations was correlated to the overall water content with a correlation coefficient of -0.94. (C) 2002 Elsevier Science......Low-field (1)H nuclear magnetic resonance (NMR) transverse relaxation was used to measure water mobility and distribution of water in fresh cod fillets. The NMR relaxations were analysed with the so-called SLICING method giving uni-exponential profiles from which the transverse relaxation time (T(2......)-values) and the relative sizes of the water populations were calculated. Two water populations with the T(2)-values of 50 and 94 ms were obtained. The shortest relaxation time was primarily found near the head, and water with the longest relaxation time was primarily found near the tail. This variation...

  5. Adding Value to Indiana's Commodities.

    Science.gov (United States)

    Welch, Mary A., Ed.

    1995-01-01

    Food processing plants are adding value to bulk and intermediate products to sell overseas. The Asian Pacific Rim economies constituted the largest market for consumer food products in 1993. This shift toward consumer food imports in this area is due to more women working outside the home, the internationalization of populations, and dramatic…

  6. Facilities Management and Added Value

    DEFF Research Database (Denmark)

    Jensen, Per Anker

    2010-01-01

    Aim: This paper aims to present different models of the concept of the added value of Facilities Management (FM), including the FM Value Map, which forms the basis of research group in EuroFM, and to present some of the results of this research collaboration. Approach and methodology: The paper i...

  7. Radiation-induced crosslinking of poly(styrene–butadiene–styrene) block copolymers and their sulfonation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun-Young [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Song, Ju-Myung; Sohn, Joon-Yong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Shul, Yong-Gun [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Shin, Junhwa, E-mail: shinj@kaeri.re.kr [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of)

    2013-12-01

    Highlights: • The c-SBS films were prepared using a gamma ray or electron beam. • The crosslinking degree of the c-SBS films were increased with the irradiation dose. • The prepared c-SBS films were sulfonated with various concentration of CSA. • The sulfonation of the c-SBS film is largely dependent on the concentration of CSA. • The sulfonation process is progressed from the surface to the inner part of c-SBS film. -- Abstract: Several crosslinked poly(styrene–butadiene–styrene) (c-SBS) block copolymer films were prepared using a gamma ray or electron beam with various irradiation doses and the prepared c-SBS film was then subjected to sulfonation using a chlorosulfonic acid (CSA) solution to introduce a sulfonic acid group. To estimate the degree of crosslinking, the gel fractions and FT-IR spectra of the c-SBS films were used and the results indicate that the degree of crosslinking is increased with an increase in the radiation dose. The surface morphology and mechanical property of the c-SBS films were observed using SEM and UTM instruments, respectively. The sulfonated c-SBS films were investigated by measuring the ion exchange capacity (IEC) and by observing the cross-sectional distribution patterns of sulfonic acid group using an SEM-EDX instrument. The IEC and SEM-EDX studies indicate that the sulfonated c-SBS membranes can be successfully prepared through the radiation crosslinking of the SBS film and the subsequent sulfonation with a diluted CSA solution.

  8. Electronically Stabilized Copoly(Styrene-Acrylic Acid Submicrocapsules Prepared by Miniemulsion Copolymerization

    Directory of Open Access Journals (Sweden)

    Minkwan Kim

    2017-07-01

    Full Text Available This work reports the preparation and characterization of poly(styrene-acrylic acid (St/AA submicrocapsules by using the miniemulsion copolymerization method. AA was introduced to miniemulsion polymerization of St to increase the zeta potential and the resulting electrostatic stability of St/AA submicrocapsules. Phytoncide oil was adopted as the core model material. Miniemulsion copolymerization of St and AA was conducted at a fixed monomer concentration (0.172 mol with a varying monomer feed ratio [AA]/[St] (0.2, 0.25, 0.33, 0.5, and 1.0. Concentrations of initiator (azobisisobutyronitrile; 1.0 × 10−3, 2.0 × 10−3, 3.0 × 10−3, and 4.0 × 10−3 mol/mol of monomer and surfactant (sodium dodecyl sulfate; 0.6 × 10−3, 1.0 × 10−3, and 1.4 × 10−3 mol were also controlled to optimize the miniemulsion copolymerization of St and AA. Dynamic light scattering and microscopic analyses confirmed the optimum condition of miniemulsion copolymerization of St and AA. Long-term colloidal stability of aqueous St/AA submicrocapsule suspension was evaluated by using TurbiscanTM Lab. In this work, the optimum condition for miniemulsion copolymerization of St and AA was determined ([AA]/[St] = 0.33; [SDS] = 1.0 × 10−3 mol; [AIBN] = 2.0 × 10−3 mol/mol of monomer. St/AA submicrocapsules prepared at the optimum condition (392.6 nm and −55.2 mV of mean particle size and zeta potential, respectively showed almost no variations in backscattering intensity (stable colloids without aggregation.

  9. Screening-level risk assessment for styrene-acrylonitrile (SAN) trimer detected in soil and groundwater.

    Science.gov (United States)

    Kirman, C R; Gargas, M L; Collins, J J; Rowlands, J C

    2012-01-01

    A screening-level risk assessment was conducted for styrene-acrylonitrile (SAN) Trimer detected at the Reich Farm Superfund site in Toms River, NJ. Consistent with a screening-level approach, on-site and off-site exposure scenarios were evaluated using assumptions that are expected to overestimate actual exposures and hazards at the site. Environmental sampling data collected for soil and groundwater were used to estimate exposure point concentrations. Several exposure scenarios were evaluated to assess potential on-site and off-site exposures, using parameter values for exposures to soil (oral, inhalation of particulates, and dermal contact) and groundwater (oral, dermal contact) to reflect central tendency exposure (CTE) and reasonable maximum exposure (RME) conditions. Three reference dose (RfD) values were derived for SAN Trimer for short-term, subchronic, and chronic exposures, based upon its effects on the liver in exposed rats. Benchmark (BMD) methods were used to assess the relationship between exposure and response, and to characterize appropriate points of departure (POD) for each RfD. An uncertainty factor of 300 was applied to each POD to yield RfD values of 0.1, 0.04, and 0.03 mg/kg-d for short-term, subchronic, and chronic exposures, respectively. Because a chronic cancer bioassay for SAN Trimer in rats (NTP 2011a) does not provide evidence of carcinogenicity, a cancer risk assessment is not appropriate for this chemical. Potential health hazards to human health were assessed using a hazard index (HI) approach, which considers the ratio of exposure dose (i.e., average daily dose, mg/kg-d) to toxicity dose (RfD, mg/kg-d) for each scenario. All CTE and RME HI values are well below 1 (where the average daily dose is equivalent to the RfD), indicating that there is no concern for potential noncancer effects in exposed populations even under the conservative assumptions of this screening-level assessment.

  10. Black holes as bubbles of AdS

    Science.gov (United States)

    Danielsson, U. H.; Dibitetto, G.; Giri, S.

    2017-10-01

    In this paper we propose that bubbles of AdS within Minkowski spacetime, stabilized at a finite radius by stiff matter and an electromagnetic gas, can be an alternative endpoint of gravitational collapse. The bubbles are horizonless with a size up to 12.5% larger than their Schwarzschild radius depending on their charge. We argue that they are stable against small perturbations, and have thermodynamical properties similar to those of real black holes. We provide a realization of the bubbles within string theory that relies on a specific brane intersection giving rise to a shell carrying dissolved charges from lower dimensional D-branes as well as a gas of open strings. We also note that our construction provides a new way of understanding the entropy of Reissner-Nordström black holes in the extremal limit.

  11. Colliding waves on a string in AdS$_3$

    CERN Document Server

    Vegh, David

    2015-01-01

    This paper is concerned with the classical motion of a string in global AdS$_3$. The initially static string stretches between two antipodal points on the boundary circle. Both endpoints are perturbed which creates cusps at a steady rate. The cusps propagate towards the interior where they collide. The behavior of the string depends on the strength of forcing. Three qualitatively different phases can be distinguished: transparent, gray, and black. The transparent region is analogous to a standing wave. In the black phase, there is a horizon on the worldsheet and cusps never reach the other endpoint. The string keeps folding and its length grows linearly over time. In the gray phase, the string still grows linearly. However, cusps do cross to the other side. The transparent and gray regions are separated by a transition point where a logarithmic accumulation of cusps is numerically observed. A simple model reproduces the qualitative behavior of the string in the three phases.

  12. Massless AdS 2 scattering and Bethe ansatz

    Science.gov (United States)

    Fontanella, A.; Torrielli, A.

    2017-09-01

    We first analyse the integrable scattering theory describing the massless excitations of AdS 2 × S 2 × T 6 superstrings in the relativistic limit. The matrix part of the S-matrix is obtained in the BMN limit from the conjectured exact expression, and compared to known S-matrices with N=1 supersymmetry in 1 + 1 dimensions. A dressing factor, yet unknown for the complete theory, is here constructed based on relativistic crossing symmetry. We derive a Bethe-ansatz condition by employing a transfer-matrix technique based on the so-called free-fermion condition. This is known to overcome the problem of lack of a reference state. We then generalise the method to the massless non-relativistic case, and compare the resulting Bethe-ansatz condition with a simple massless limit of the one conjectured by Sorokin, Tseytlin, Wulff and Zarembo.

  13. Thermodynamics of charged Lovelock: AdS black holes

    Energy Technology Data Exchange (ETDEWEB)

    Prasobh, C.B.; Suresh, Jishnu; Kuriakose, V.C. [Cochin University of Science and Technology, Department of Physics, Cochin (India)

    2016-04-15

    We investigate the thermodynamic behavior of maximally symmetric charged, asymptotically AdS black hole solutions of Lovelock gravity. We explore the thermodynamic stability of such solutions by the ordinary method of calculating the specific heat of the black holes and investigating its divergences which signal second-order phase transitions between black hole states. We then utilize the methods of thermodynamic geometry of black hole spacetimes in order to explain the origin of these points of divergence. We calculate the curvature scalar corresponding to a Legendre-invariant thermodynamic metric of these spacetimes and find that the divergences in the black hole specific heat correspond to singularities in the thermodynamic phase space. We also calculate the area spectrum for large black holes in the model by applying the Bohr-Sommerfeld quantization to the adiabatic invariant calculated for the spacetime. (orig.)

  14. Adiabatic pumping solutions in global AdS

    Science.gov (United States)

    Carracedo, Pablo; Mas, Javier; Musso, Daniele; Serantes, Alexandre

    2017-05-01

    We construct a family of very simple stationary solutions to gravity coupled to a massless scalar field in global AdS. They involve a constantly rising source for the scalar field at the boundary and thereby we name them pumping solutions. We construct them numerically in D = 4. They are regular and, generically, have negative mass. We perform a study of linear and nonlinear stability and find both stable and unstable branches. In the latter case, solutions belonging to different sub-branches can either decay to black holes or to limiting cycles. This observation motivates the search for non-stationary exactly timeperiodic solutions which we actually construct. We clarify the role of pumping solutions in the context of quasistatic adiabatic quenches. In D = 3 the pumping solutions can be related to other previously known solutions, like magnetic or translationally-breaking backgrounds. From this we derive an analytic expression.

  15. Electron beam processing of fresh produce - A critical review

    Science.gov (United States)

    Pillai, Suresh D.; Shayanfar, Shima

    2018-02-01

    To meet the increasing global demand for fresh produce, robust processing methods that ensures both the safety and quality of fresh produce are needed. Since fresh produce cannot withstand thermal processing conditions, most of common safety interventions used in other foods are ineffective. Electron beam (eBeam) is a non-thermal technology that can be used to extend the shelf life and ensure the microbiological safety of fresh produce. There have been studies documenting the application of eBeam to ensure both safety and quality in fresh produce, however, there are still unexplored areas that still need further research. This is a critical review on the current literature on the application of eBeam technology for fresh produce.

  16. Recycling of mixed plastic waste from electrical and electronic equipment. Added value by compatibilization.

    Science.gov (United States)

    Vazquez, Yamila V; Barbosa, Silvia E

    2016-07-01

    Plastic waste from electrical and electronic equipment (WEEE) grows up exponentially fast in the last two decades. Either consumption increase of technological products, like cellphones or computers, or the short lifetime of this products contributes to this rise generating an accumulation of specific plastic materials such ABS (Acrylonitrile-Butadiene-Styrene), HIPS (High impact Polystyrene), PC (Polycarbonate), among others. All of they can be recycled by themselves. However, to separate them by type is neither easy nor economically viable, then an alternative is recycling them together as a blend. Taking into account that could be a deterioration in final properties, to enhance phase adhesion and add value to a new plastic WEEE blend a compatibilization is needed. In this work, a systematical study of different compatibilizers for blends of HIPS and ABS from WEEE was performed. A screening analysis was carried out by adding two different compatibilizer concentration (2wt% and 20wt%) on a HIPS/ABS physical blend 80/20 proportion from plastic e-waste. Three copolymers were selected as possible compatibilizers by their possible affinity with initial plastic WEEE. A complete characterization of each WEEE was performed and compatibilization efficiency was evaluated by comparing either mechanical or morphological blends aspects. Considering blends analyzed in this work, the best performance was achieved by using 2% of styrene-acrylonitrile rubber, obtaining a compatibilized blend with double ultimate strength and modulus respect to the physical blend, and also improve mechanical properties of initial WEEE plastics. The proposed way is a promise route to improve benefit of e-scrap with sustainable, low costs and easy handling process. Consequently, social recycling interest will be encouraged by both ecological and economical points of view. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Worldsheet dilatation operator for the AdS superstring

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez, Israel [Departamento de Física, Universidad Técnica Federico Santa María,Casilla 110-V, Valparaíso (Chile); Institut für Mathematik und Institut für Physik, Humboldt-Universität zu Berlin,IRIS Haus, Zum Großen Windkanal 6, 12489 Berlin (Germany); Vallilo, Brenno Carlini [Departamento de Ciencias Físicas, Universidad Andres Bello,Republica 220, Santiago (Chile)

    2016-05-23

    In this work we propose a systematic way to compute the logarithmic divergences of composite operators in the pure spinor description of the AdS{sub 5}×S{sup 5} superstring. The computations of these divergences can be summarized in terms of a dilatation operator acting on the local operators. We check our results with some important composite operators of the formalism.

  18. Brownian motion in AdS/CFT

    NARCIS (Netherlands)

    de Boer, J.; Hubeny, V.E.; Rangamani, M.; Shigemori, M.

    2009-01-01

    We study Brownian motion and the associated Langevin equation in AdS/CFT. The Brownian particle is realized in the bulk spacetime as a probe fundamental string in an asymptotically AdS black hole background, stretching between the AdS boundary and the horizon. The modes on the string are excited by

  19. Effects of Molecular Iodine and 4-tert-Butylcatechol Radical Inhibitor on the Radical Polymerization of Styrene

    Directory of Open Access Journals (Sweden)

    Mojtaba Bozorg

    2017-05-01

    Full Text Available The presence of molecular iodine was studied in relation the molecular weight and molecular weight distribution of polystyrene, produced by radical poly merization. Radical polymerization of styrene initiated by 2,2׳-azobisisobutyronitrile (AIBN was performed at 70°C in the presence of molecular iodine. The synthesized polymers were characterized by gel permeation chromatography (GPC and proton- nuclear magnetic resonance (1H NMR techniques. The results of these reactions including conversion data, number-average molecular weight and molecular weight distribution were compared with those obtained for styrene radical polymerization initiated by AIBN at the same temperature in the absence of molecular iodine. It was found that the presence of iodine had a profound effect on the molecular weight and its distribution in the produced polystyrene. This was attributed to the ability of iodine to control the polymerization of styrene initiated by AIBN via reverse iodine transfer polymerization (RITP mechanism. The polymer produced by this method had a molecular weight of 10600 g/mol with a molecular weight polydispersity index of 1.3. Due to the importance of induction period in reverse iodine transfer radical polymerization, increasing the temperature to 120°C during the induction period resulted in shorter induction periods and the produced species led to better control of the molecular weight. Also, due to the role of iodine molecules as a radical inhibitor, the presence of a secondary radical inhibitor, i.e. 4-tert-butylcatechol, along with the iodine was investigated in radical polymerization of polystyrene initiated by AIBN. It was observed that the secondary radical inhibitor prevented the consumption of the iodine molecules by the radicals produced from decomposition of the AIBN initiator; therefore, alkyl halides were not produced during the induction period.

  20. Anatomical Glenoid Reconstruction Using Fresh Osteochondral Distal Tibia Allograft After Failed Latarjet Procedure.

    Science.gov (United States)

    Sanchez, Anthony; Ferrari, Marcio B; Akamefula, Ramesses A; Frank, Rachel M; Sanchez, George; Provencher, Matthew T

    2017-04-01

    In the treatment of recurrent anterior glenohumeral instability, the Latarjet procedure has been shown to fail. This results in a need for viable revisional procedures for patients who present with this challenging pathology. We report our preferred technique for anatomical glenoid reconstruction using a fresh osteochondral distal tibia allograft after a failed Latarjet procedure. This bony augmentation technique employs a readily available dense, weight-bearing osseous tissue source that has excellent conformity, as well as the added benefit of a cartilaginous surface to correct chondral deficiencies. Given its effectiveness in the Latarjet revision setting and low complication rate, the distal tibia allograft is a reasonable treatment option.

  1. Electromyogram as a measure of heavy metal toxicity in fresh water and salt water mussels

    Energy Technology Data Exchange (ETDEWEB)

    Kidder, G.W. III [Illinois State Univ., Normal, IL (United States)]|[Mt. Desert Island Biological Lab., Salsbury Cove, ME (United States); McCoy, A.A. [Mt. Desert Island Biological Lab., Salsbury Cove, ME (United States)]|[Brown Univ., Providence, RI (United States)

    1996-02-01

    The response of bivalves to heavy metals and other toxins has usually been determined by observing valve position. Since mussels close their valves to avoid noxious stimuli, experimental delivery of chemicals ins uncertain. To obtain constant results plastic spacers can be employed to hold the valves apart. This obviates valve position as an index of response and some other method is required. Electromyography of intact mussels is one such index, giving a simple, effective, and quantitative measurement of activity. Experiments are reported in this article on the effects of added mercury on salt water and fresh water species.

  2. Factors affecting quality and safety of fresh-cut produce.

    Science.gov (United States)

    Francis, G A; Gallone, A; Nychas, G J; Sofos, J N; Colelli, G; Amodio, M L; Spano, G

    2012-01-01

    The quality of fresh-cut fruit and vegetable products includes a combination of attributes, such as appearance, texture, and flavor, as well as nutritional and safety aspects that determine their value to the consumer. Nutritionally, fruit and vegetables represent a good source of vitamins, minerals, and dietary fiber, and fresh-cut produce satisfies consumer demand for freshly prepared, convenient, healthy food. However, fresh-cut produce deteriorates faster than corresponding intact produce, as a result of damage caused by minimal processing, which accelerates many physiological changes that lead to a reduction in produce quality and shelf-life. The symptoms of produce deterioration include discoloration, increased oxidative browning at cut surfaces, flaccidity as a result of loss of water, and decreased nutritional value. Damaged plant tissues also represent a better substrate for growth of microorganisms, including spoilage microorganisms and foodborne pathogens. The risk of pathogen contamination and growth is one of the main safety concerns associated with fresh-cut produce, as highlighted by the increasing number of produce-linked foodborne outbreaks in recent years. The pathogens of major concern in fresh-cut produce are Listeria monocytogenes, pathogenic Escherichia coli mainly O157:H7, and Salmonella spp. This article describes the quality of fresh-cut produce, factors affecting quality, and various techniques for evaluating quality. In addition, the microbiological safety of fresh-cut produce and factors affecting pathogen survival and growth on fresh-cut produce are discussed in detail.

  3. Radical polymerization of styrene controlled by half-sandwich Mo(III)/Mo(IV) couples: all basic mechanisms are possible.

    Science.gov (United States)

    Le Grognec, E; Claverie, J; Poli, R

    2001-10-03

    Density functional calculations of bond dissociation energies (BDEs) have been used as a guide to the choice of metal system suitable for controlling styrene polymerization by either the stable free radical polymerization (SFRP) or the atom transfer radical polymerization (ATRP) mechanism. In accord with the theoretical prediction, CpMo(eta(4)-C(4)H(6))(CH(2)SiMe(3))(2), 2, is not capable of yielding SFRP of styrene. Still in accord with theoretical prediction, CpMo(eta(4)-C(4)H(6))Cl(2), 1, CpMo(PMe(3))(2)Cl(2), 3, and CpMo(dppe)Cl(2) (dppe = 1,2-bis(diphenylphosphino)ethane), 4, yield controlled styrene polymerization by the SFRP mechanism in the presence of 2,2'-azobisisobutyronitrile (AIBN). This arises from the generation of a putative Mo(IV) alkyl species from the AIBN-generated radical addition to the Mo(III) compound. The controlled nature of the polymerizations is indicated by linear M(n) progression with the conversion in all cases and moderate polydispersity indices (PDIs). Controlled polymerization of styrene is also given by compounds 3 and 4 in combination with alkyl bromides. These complexes then operate by the ATRP mechanism, again in accord with the theoretical predictions. Controlled character is revealed by linear increase of M(n) versus conversion, low PDIs, a stop-and-go experiment, and (1)H NMR and MALDI-TOF analyses of the polymer end groups. The same controlled polymerization is given by a "reverse" ATRP experiment, starting from AIBN and CpMo(PMe(3))(2)Cl(2)Br, 5. On the other hand, when compound 1 or 2 is used in combination with an alkyl bromide (as for an ATRP experiment), the isolated polystyrene shows by M(n), (1)H NMR, and MALDI-TOF analyses that catalytic chain transfer (CCT) radical polymerization takes place in this case. Kinetics simulations underscore the conditions regulating the radical polymerization mechanism and the living character of the polymerization. The complexes herein described are ineffective at controlling the

  4. The structure and dynamics of thin poly(styrene)-b-(polybutadiene) copolymer films studied by x-ray scattering

    Science.gov (United States)

    Song, Sanghoon; Byun, Youngsuk; Kim, Jeeun; Eom, Daeyong; Cha, Wonsuk; Kim, Hyunjung

    2007-03-01

    We have investigated the structure and dynamics of thin diblock copolymer films of poly(styrene)-b-poly(butadiene) using x-ray reflectivity, diffuse scattering, grazing incidence small angle scattering (GISAXS), and x-ray photon correlation spectroscopy (XPCS), respectively. The measurements were performed at temperatures below and above the order-disorder transition temperature (ODT) of bulk with different film thicknesses. The x-ray reflectivity and GISAXS results show that the structural changes appear at lower temperature than ODT of bulk. These results will be discussed with the findings from the XPCS.

  5. Synthesis of Hydrophilic and Amphiphilic Acryl Sucrose Monomers and Their Copolymerisation with Styrene, Methylmethacrylate and α- and β-Pinenes

    Directory of Open Access Journals (Sweden)

    Maria Teresa Barros

    2010-04-01

    Full Text Available Herein, we report the synthesis of monomethacryloyl sucrose esters, and their successful free radical homo- and co-polymerisation with styrene, methylmethacrylate, α- and β-pinene. The chemical, physical, structural and surface chemical properties of these polymers, containing a hydrophobic olefin backbone and hydrophilic sugar moieties as side chains, have been investigated. Biodegradation tests of the copolymer samples by a microbial fungal culture (Aspergillus niger method showed good biodegradability. The chemical structure and surface chemistry of the synthesized homo- and co-polymers demonstrate their potential technological relevance as amphiphilic and biodegradable polymers.

  6. A study of the initiator concentration’s effect on styrene-divinylbenzene polymerization with iron particles

    Directory of Open Access Journals (Sweden)

    Bárbara M. da Conceição

    2011-01-01

    Full Text Available This paper describes the preparation of magnetic copolymer obtained from suspension polymerization of styrene (Sty and divinylbenzene (DVB in the presence of iron particles treated and not treated with oleic acid. The magnetic copolymers were characterized according to their morphology, particle size distribution and magnetic properties. The results show that incorporation of iron particles significantly changed the particles’ morphology. All samples presented higher saturation magnetization than the values reported in the literature and the particle size distribution was more monodisperse when the polymerization was conducted with 5%wt of benzoyl peroxide (BPO.

  7. Preparation, characterization and conductivity study of nitro-mercurated styrene butadiene rubber/silver doped zinc oxide nanocomposites

    Science.gov (United States)

    Anilkumar, T.; Naik, Adarsh Ajith; Ramesan, M. T.

    2017-06-01

    Here we report the preparation of nitromercurated styrene butadiene rubber (NMSBR)/silver doped zinc oxide nanocomposite by inexpensive and ecofriendly two roll mill mixing. The composites were characterized by UV, FTIR, XRD, SEM, TGA and conductivity measurements. UV and FTIR spectrum indicated the interfacial interaction between the polymer and nanoparticles.XRD and SEM images showed the uniform arrangement of nanoparticles within the macromolecular chain. TGA study indicated the better thermal resistance of the composite. The dielectric properties and AC conductivity ofnanocomposites were much greater than nitromercurated SBR and they may be used as multifunctional materials for nanoelectronic devices.

  8. Effect of crosslinking density on biaxial relaxation of SBR by using reduced variables. [Styrene-Butadiene Rubber

    Science.gov (United States)

    Arenz, R. J.

    1974-01-01

    The use of reduced variables to account for the effect of crosslinking density in a styrene-butadiene rubber (SBR) system is demonstrated for general biaxial stress states. Recently published results from stress relaxation tests on five SBR vulcanizates crosslinked to different degrees by tetramethylthiuram disulfide were superposed by using the crosslinking density as a reduction variable. The equilibrium shear modulus calculated from the master relaxation curve at long reduced times was in satisfactory agreement with other results for SBR. The time-axis shifts were related in a linear logarithmic manner to the crosslinking density but had a slope slightly less than values previously reported for elastomer systems.

  9. Synthesis and Characterization of Amphiphilic Graft Copolymers of Poly (1,3dioxolane) Macromonomers with Styrene and Methyl Methacrylate

    Science.gov (United States)

    Bendaikha, H.; Clisson, G.; Khoukh, A.; François, J.; Kada, S. Ould; Krallafa, A.

    2008-08-01

    Methacrylate-terminated Poly (1,3dioxolane) (PDXL) macromonomers were synthesized by cationic ring-opening polymerization in the presence of 2-hydroxypropyl methacrylate (2-HPMA) as transfer agent. Molecular weights and polydispersity index of the PDXL macromonomers were evaluated by size exclusion chromatography (SEC) and 1H-NMR. Copolymerizations of PDXL macromonomers with styrene (St) and methyl methacrylate (MMA) were carried out using various feed molar ratios. Monomer reactivity ratios between the macromonomers and the comonomers were estimated from the copolymerization results. Glass transition temperatures of the copolymers were found to decrease with an increase in the amount of PDXL in the copolymers.

  10. The Effects of Small amounts of Methanol on the Ionizing Radiation Induced Polymerization and Photopolymerization of Styrene.

    Science.gov (United States)

    Tang, Fuh-Wei

    1990-08-01

    The mechanisms whereby ionizing radiation produce the species which initiate neutral free radical and ionic polymerization are investigated. Of particular interest is the remarkable enhancement effect on radiation induced polymerization of styrene by small concentrations of methanol. The approach is to compare the effects of methanol on the steady state polymerization of styrene induced by two different initiation methods: (1) gamma ray; (2) ultraviolet light (UV). In addition to these steady state reaction studies, microsecond pulse radiolysis with 6 MeV electrons is used to study the transient aspects of styrene polymerization and especially, the effect of methanol on the intiation step. The results for photopolymerization initiated with wavelengths above 280 nm, and therefore dominated by free radical polymerization, show that methanol has no sensitizing effect. This leads to eliminate the interaction between methanol and free radical in the initiation stage of a polymerization. By means of studies with different alcohols and an analysis of the dimer and trimer yield, a proton donor mechanism is successfully established for the enhancement effect of methanol on the radiation induced polymerization of styrene. The role of methanol is explained to serve as a rapid proton donor to the anion radical converting the latter to a neutral propagating free radical. The resulting methoxide anion then neutralizes the cation radical converting it to an additional neutral propagating free radical. Trace amounts of methanol (less than 0.05 M) in system with 2-3 mM water is found to have a desensitizing effect because of a quenching influence of methanol on propagating free ionic species; this effect is not observed in the water saturated (35 mM water) system or even at higher concentrations of methanol in the system with 3 mM water. In pulse radiolysis, a quantitative agreement between steady state polymerization and pulse radiolysis is for the first time obtained in the

  11. Grafting of styrene onto poly(vinylidene fluoride) films by gamma irradiation; Enxertia de estireno em filmes de poli(fluoreto de vinilideno) induzida por irradiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, H.P.; Souza, C.P. de; Parra, D.F.; Lugao, A.B., E-mail: hp.ferreira@yahoo.com.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente

    2010-07-01

    Radiation induced grafting of styrene onto poly(vinylidene fluoride) (PVDF) was studied owing to the crescent interest in use of grafted films to produce membranes with ion exchange capability. A Cobalt-60 source was used, with doses of 5 and 10 kGy, at dose rate of 5 kGy.h{sup -1}, at room temperature, inert atmosphere and according to the simultaneous method. Solutions of styrene/toluene (1:1, v/v) and styrene/N,N-dimethylformamide (DMF) (1:1, v/v) were used. The films were characterized by FT-IR spectroscopy (Infrared Spectroscopy), Differential Scanning Calorimetry (DSC), Thermogravimetric Measurement (TG) and the degree of grafting (DOG) were calculated gravimetrically. Results shown that in studied conditions, DMF allow greatest DOG than toluene and that increasing the irradiation dose correspond an increase in DOG. Infrared and thermal analyses confirmed the presence in the grafted polymers. (author)

  12. Stereoselective Copolymerization of Styrene with Terpenes Catalyzed by an Ansa-Lanthanidocene Catalyst: Access to New Syndiotactic Polystyrene-Based Materials

    Directory of Open Access Journals (Sweden)

    Eva Laur

    2017-11-01

    Full Text Available The copolymerization of bio-renewable β-myrcene or β-farnesene with styrene was examined using an ansa-neodymocene catalyst, affording two series of copolymers with high styrene content and unprecedented syndioregularity of the polystyrene sequences. The incorporation of terpene in the copolymers ranged from 5.6 to 30.8 mol % (β-myrcene and from 2.5 to 9.8 mol % (β-farnesene, respectively. NMR spectroscopy and DSC analyses suggested that the microstructure of the copolymers consists of 1,4- and 3,4-poly(terpene units randomly distributed along syndiotactic polystyrene chains. The thermal properties of the copolymers are strongly dependent on the terpene content, which is easily controlled by the initial feed. The terpolymerization of styrene with β-myrcene in the presence of ethylene was also examined.

  13. Determination of styrene content in Gorgonzola PDO cheese by headspace solid phase micro-extraction (HS-SPME) and gas-chromatography mass-spectrometry (GC-MS).

    Science.gov (United States)

    Chiesa, L M; Panseri, S; Soncin, S; Vallone, L; Dragoni, I

    2010-06-01

    Control of the composition of products that are intended for use as packaging material is essential, particularly when these products come into direct contact with food. It is well known that plastics are not inert and that their residual monomers, starting substances, and additives are able to migrate into the food they contact. Among plastics, styrene is a common compound found in many plastic containers that can also be produced by the oxidation of Penicillium roqueforti used in gorgonzola Protected Denomination of Origin cheese manufacturing. Therefore, solid-phase microextraction combined with gas chromatography/mass spectrometry was applied in the present work to determine the styrene content in packaged and unpackaged gorgonzola cheese samples to understand styrene migration phenomena from plastic containers.

  14. Realizing "value-added" metrology

    Science.gov (United States)

    Bunday, Benjamin; Lipscomb, Pete; Allgair, John; Patel, Dilip; Caldwell, Mark; Solecky, Eric; Archie, Chas; Morningstar, Jennifer; Rice, Bryan J.; Singh, Bhanwar; Cain, Jason; Emami, Iraj; Banke, Bill, Jr.; Herrera, Alfredo; Ukraintsev, Vladamir; Schlessinger, Jerry; Ritchison, Jeff

    2007-03-01

    The conventional premise that metrology is a "non-value-added necessary evil" is a misleading and dangerous assertion, which must be viewed as obsolete thinking. Many metrology applications are key enablers to traditionally labeled "value-added" processing steps in lithography and etch, such that they can be considered integral parts of the processes. Various key trends in modern, state-of-the-art processing such as optical proximity correction (OPC), design for manufacturability (DFM), and advanced process control (APC) are based, at their hearts, on the assumption of fine-tuned metrology, in terms of uncertainty and accuracy. These trends are vehicles where metrology thus has large opportunities to create value through the engineering of tight and targetable process distributions. Such distributions make possible predictability in speed-sorts and in other parameters, which results in high-end product. Additionally, significant reliance has also been placed on defect metrology to predict, improve, and reduce yield variability. The necessary quality metrology is strongly influenced by not only the choice of equipment, but also the quality application of these tools in a production environment. The ultimate value added by metrology is a result of quality tools run by a quality metrology team using quality practices. This paper will explore the relationships among present and future trends and challenges in metrology, including equipment, key applications, and metrology deployment in the manufacturing flow. Of key importance are metrology personnel, with their expertise, practices, and metrics in achieving and maintaining the required level of metrology performance, including where precision, matching, and accuracy fit into these considerations. The value of metrology will be demonstrated to have shifted to "key enabler of large revenues," debunking the out-of-date premise that metrology is "non-value-added." Examples used will be from critical dimension (CD

  15. Combined application of modified atmosphere packaging and superchilled storage to extend the shelf life of fresh cod (Gadus morhua) loins.

    Science.gov (United States)

    Wang, T; Sveinsdóttir, K; Magnússon, H; Martinsdóttir, E

    2008-01-01

    Development of new technologies and preservation methods to offer conveniently packed fish with sufficient keeping quality is important to meet increasing demand for value-added fresh fish products on the market. The aim of this study was to investigate the effect of combined application of modified atmosphere packaging (MAP) and superchilled storage on the shelf life of fresh cod loins. Fresh cod loins were packed in polystyrene boxes and in MA (CO(2)/N(2)/O(2): 50%/45%/5%) on day 3 postcatch and stored at chilled (1.5 degrees C) and superchilled (-0.9 degrees C) temperatures. Quantitative descriptive analysis (QDA) and physical, chemical, and microbial analyses were carried out during the 21 d of storage. Superchilled storage alone compared with traditional chilled storage in polystyrene boxes increased the total shelf life (days from catch) of cod loins from 9 to 16 or 17 d. Chilled MA packaging increased the shelf life from 9 to 14 d and when MAP and superchilled storage were combined, a synergistic effect was observed and the shelf life was further extended to at least 21 d. It is noteworthy that the characteristic fresh and sweet taste can be maintained longer under such conditions. This could contribute to enhanced eating quality of fresh cod fillets for consumers in distant markets. However, MAP combined with superchilled storage resulted in different textural properties. Superchilled MA packed cod loins had more meaty texture compared to other sample groups after 7-d storage.

  16. Liquid-liquid phase separation in dilute solutions of poly(styrene sulfonate) with multivalent cations: Phase diagrams, chain morphology, and impact of temperature.

    Science.gov (United States)

    Hansch, Markus; Hämisch, Benjamin; Schweins, Ralf; Prévost, Sylvain; Huber, Klaus

    2018-01-07

    The dilute solution behavior of sodium poly(styrene sulfonate) is studied in the presence of trivalent Al3+ and bivalent Ba2+ cations at various levels of excess NaCl. The study evaluates the phase behavior and the morphology of the polyelectrolyte chains with increasing extent of decoration with the Al3+ and Ba2+ cations and analyses the effect of temperature on these decorated chains. The phase behavior is presented in the form of the cation concentration versus the respective poly(styrene sulfonate) concentration, recorded at the onset of precipitation. Whereas poly(styrene sulfonate) with Al3+ exhibits a linear phase boundary, denoted as the "threshold line," which increases with increasing poly(styrene sulfonate) concentration, Ba2+ cations show a threshold line which is independent of the poly(styrene sulfonate) concentration. An additional re-entrant phase, at considerably higher cation content than those of the threshold lines, is observed with Al3+ cations but not with Ba2+ cations. The threshold line and the re-entrant phase boundary form parts of the liquid-liquid phase boundary observed at the limit of low polymer concentration. The dimensions of the polyelectrolyte chains shrink considerably while approaching the respective threshold lines on increase of the Al3+ and Ba2+ cation content. However, subtle differences occur between the morphological transformation induced by Al3+ and Ba2+. Most strikingly, coils decorated with Al3+ respond very differently to temperature variations than coils decorated with Ba2+ do. As the temperature increases, the poly(styrene sulfonate) chains decrease their size in the presence of Al3+ cations but increase in size in the presence of Ba2+ cations.

  17. Investigations on neurotoxicity of chemical substances at the workplace. VII. Longitudinal study with determination of nerve conduction velocities in persons occupationally exposed to styrene

    Energy Technology Data Exchange (ETDEWEB)

    Triebig, G.; Schaller, K.H.; Valentin, H.

    1985-01-01

    The aim of this longitudinal study was to investigate whether long-term exposure to styrene is associated with functional disorders of the peripheral nervous system. Eleven workers (age: 24 to 54 years) of a polyester resin boat industry were studied neurophysiologically and biochemically in 1980 and 1983. The duration of styrene-exposure varied from 3 to 7 years, with a median of 4 years. The control group was comprised of 11 non-styrene-exposed workers of similar age. Air Monitoring with passive samplers was performed on different days for each person. The mean styrene concentrations were 114, 97 and 92 ppm respectively and therefore in the magnitude of the current MAK-value of 100 ppm in the Federal Republic of Germany (FRG). For Biological Monitoring styrene in blood (S-B) and mandelic acid (MA) as well as phenylglyoxylic-acid (PGA) in urine were determined in post-shift samples. The median values for MA at four different sampling times were 816, 1660, 1101 and 1224 mg/g creatinine and for PGA 200, 273, 342 and 336 mg/g creatinine respectively. These levels were below the current Biologischer Arbeitsstoff Toleranzwert (BAT-Wert) for MA (2000 mg/l) and MA + PGA (2500 mg/l). The S-B concentrations ranged from 0.05 mg/l to 3.26 mg/l, with mean values of 0.92 and 0.70 mg/l. The nerve conduction velocities (NCV) of motor and sensory nerve fibers (N. ulnaris and/or N. medianus) showed no significant differences between styrene-exposed workers and age-matched control persons. There were no hints of dose-effect-relationships by correlation analyses. Furthermore the follow-up determination revealed no significant changes regarding NCV.

  18. Influence of Glass Fiber on Fresh and Hardened Properties of Self Compacting Concrete

    Science.gov (United States)

    Bharathi Murugan, R.; Haridharan, M. K.; Natarajan, C.; Jayasankar, R.

    2017-07-01

    The practical need of self-compacting concrete (SCC) is increasing due to increase in the infrastructure competence all over the world. The effective way of increasing the strength of concrete and enhance the behaviour under extreme loading (fire) is the keen interest. Glass fibers were added for five different of volume fractions (0%, 0.1%, 0.3%, 0.5% and 0.6%) to determine the optimum percentage of glass fiber without compensating the fresh properties and enhanced hardened properties of SCC concrete. The fresh state of concrete is characterized by slump flow, T-50cm slump flow, and V-funnel and L- box tests. The results obtained in fresh state are compared with the acceptance criteria of EFNARC specification. Concrete specimens were casted to evaluate the hardened properties such as compressive strength, split tensile strength, flexural strength and modulus of elasticity. Incorporation the glass fiber into SCC reduces the workability but within the standard specification. The hardened properties of SCC glass fiber reinforced concrete were enhanced, due to bridging the pre-existing micro cracks in concrete by glass fiber addition.

  19. The model relationship of wastes for parameter design with green lean production of fresh water

    Directory of Open Access Journals (Sweden)

    Mastiadi Tamjidillah

    2017-12-01

    Full Text Available Lean manufacturing is about eliminating waste including the seven traditional, this writing suggested an observation on no value added of seven wastes influencing the process of fresh water production. The relationship value among waste was statistically verified to create an approach for continuous improvement action. Thus, the main goal of this research is to develop a methodology of relationship among wastes and eliminate them. In relationship among wastes, it could be known that the high value indicating how often it happened in the production process gave direct cause in the system of fresh water treatment. A recommendation to reduce the highest value of waste is by doing improvement on parameter setting to obtain an optimum mixing model between water supply, alum and stroke pump with Taguchi method. The interaction of relationship among these seven types of waste can be portrayed using fishbone diagram and a relationship model among wastes using PLS smart (partial least squares. The final relationship model with the highest value of waste was analyzed using off-line quality control to upgrade the quality of fresh water used as the basis to eliminate waste and find out the optimal parameter of mixing process in accordance with the health standard.

  20. FRESH-WATER GREEN ALGAE (CHLOROPHYTA AS A NATURAL PIGMENT FOR MOJOSARI DUCKS

    Directory of Open Access Journals (Sweden)

    B. Indarsih

    2015-09-01

    Full Text Available An experiment in a completely randomize design was undertaken to study the use of fresh-watergreen algae as a yolk coloring agent in Mojosari ducks during a laying period on productiveperformance and egg quality from 36 to 44 wk of age. A total of 80 thirty-six wk–old laying ducks weredivided into four dietary treatments and each of four replicates with 5 birds. Diets were formulated witha commercial concentrate, rice bran and yellow corn (2:4:4 according to a commercial standard diet asa control, and three other dietary treatments with 2, 4 or 8% of green algae were included. Fresh watergreen algae had a significant effect on the feed uptake, egg production, and feed conversion ratio (FCR(p<0.05. Egg production and FCR improved at added 2 and 4% green algae. No differences wereobserved in egg yolk index, albumen index, Haugh Unit, and egg shell thickness (P>0.05 except eggyolk color. The yolk color increased within 7 days after feeding with the test diets. The present studyindicated that fresh-water green algae could be used as a natural coloring agent in laying ducks and at8% of green algae showed the highest score of (Roche Yellow Color-15.