Predictors of occupational exposure to styrene and styrene‐7,8‐oxide in the reinforced plastics industry

PubMed Central

Serdar, B; Tornero‐Velez, R; Echeverria, D; Nylander‐French, L A; Kupper, L L; Rappaport, S M

2006-01-01

Objective To identify demographic and work related factors that predict blood levels of styrene and styrene‐7,8‐oxide (SO) in the fibreglass reinforced plastics (FRP) industry. Methods Personal breathing‐zone air samples and whole blood samples were collected repeatedly from 328 reinforced plastics workers in the Unuted States between 1996 and 1999. Styrene and its major metabolite SO were measured in these samples. Multivariable linear regression analyses were applied to the subject‐specific levels to explain the variation in exposure and biomarker levels. Results Exposure levels of styrene were approximately 500‐fold higher than those of SO. Exposure levels of styrene and SO varied greatly among the types of products manufactured, with an 11‐fold range of median air levels among categories for styrene and a 23‐fold range for SO. Even after stratification by job title, median exposures of styrene and SO among laminators varied 14‐ and 31‐fold across product categories. Furthermore, the relative proportions of exposures to styrene and SO varied among product categories. Multivariable regression analyses explained 70% and 63% of the variation in air levels of styrene and SO, respectively, and 72% and 34% of the variation in blood levels of styrene and SO, respectively. Overall, air levels of styrene and SO appear to have decreased substantially in this industry over the last 10–20 years in the US and were greatest among workers with the least seniority. Conclusions As levels of styrene and SO in air and blood varied among product categories in the FRP industry, use of job title as a surrogate for exposure can introduce unpredictable measurement errors and can confound the relation between exposure and health outcomes in epidemiology studies. Also, inverse relations between the intensity of exposure to styrene and SO and years on the job suggest that younger workers with little seniority are typically exposed to higher levels of styrene and SO

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

PubMed

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

2018-05-01

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.

Styrene induces an inflammatory response in human lung epithelial cells via oxidative stress and NF-{kappa}B activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roeder-Stolinski, Carmen; Fischaeder, Gundula; Oostingh, Gertie Janneke

2008-09-01

Styrene is a volatile organic compound (VOC) that is widely used as a solvent in many industrial settings. Chronic exposure to styrene can result in irritation of the mucosa of the upper respiratory tract. Contact of styrene with epithelial cells stimulates the expression of a variety of inflammatory mediators, including the chemotactic cytokine monocyte chemoattractant protein-1 (MCP-1). To characterise the underlying mechanisms of the induction of inflammatory signals by styrene, we investigated the influence of this compound on the induction of oxidative stress and the activation of the nuclear factor-kappa B (NF-{kappa}B) signalling pathway in human lung epithelial cells (A549).more » The results demonstrate that styrene-induced MCP-1 expression, as well as the expression of the oxidative stress marker glutathione S-transferase (GST), is associated with a concentration dependent pattern of NF-{kappa}B activity. An inhibitor of NF-{kappa}B, IKK-NBD, and the anti-inflammatory antioxidant N-acetylcysteine (NAC) were both effective in suppressing styrene-induced MCP-1 secretion. In addition, NAC was capable of inhibiting the upregulation of GST expression. Our findings suggest that the activation of the NF-{kappa}B signalling pathway by styrene is mediated via a redox-sensitive mechanism.« less

Production of biorenewable styrene: utilization of biomass-derived sugars and insights into toxicity.

PubMed

Lian, Jieni; McKenna, Rebekah; Rover, Marjorie R; Nielsen, David R; Wen, Zhiyou; Jarboe, Laura R

2016-05-01

Fermentative production of styrene from glucose has been previously demonstrated in Escherichia coli. Here, we demonstrate the production of styrene from the sugars derived from lignocellulosic biomass depolymerized by fast pyrolysis. A previously engineered styrene-producing strain was further engineered for utilization of the anhydrosugar levoglucosan via expression of levoglucosan kinase. The resulting strain produced 240 ± 3 mg L(-1) styrene from pure levoglucosan, similar to the 251 ± 3 mg L(-1) produced from glucose. When provided at a concentration of 5 g L(-1), pyrolytic sugars supported styrene production at titers similar to those from pure sugars, demonstrating the feasibility of producing this important industrial chemical from biomass-derived sugars. However, the toxicity of contaminant compounds in the biomass-derived sugars and styrene itself limit further gains in production. Styrene toxicity is generally believed to be due to membrane damage. Contrary to this prevailing wisdom, our quantitative assessment during challenge with up to 200 mg L(-1) of exogenously provided styrene showed little change in membrane integrity; membrane disruption was observed only during styrene production. Membrane fluidity was also quantified during styrene production, but no changes were observed relative to the non-producing control strain. This observation that styrene production is much more damaging to the membrane integrity than challenge with exogenously supplied styrene provides insight into the mechanism of styrene toxicity and emphasizes the importance of verifying proposed toxicity mechanisms during production instead of relying upon results obtained during exogenous challenge.

Rational and combinatorial approaches to engineering styrene production by Saccharomyces cerevisiae.

PubMed

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

2014-08-21

Styrene is an important building-block petrochemical and monomer used to produce numerous plastics. Whereas styrene bioproduction by Escherichia coli was previously reported, the long-term potential of this approach will ultimately rely on the use of hosts with improved industrial phenotypes, such as the yeast Saccharomyces cerevisiae. Classical metabolic evolution was first applied to isolate a mutant capable of phenylalanine over-production to 357 mg/L. Transcription analysis revealed up-regulation of several phenylalanine biosynthesis pathway genes including ARO3, encoding the bottleneck enzyme DAHP synthase. To catalyze the first pathway step, phenylalanine ammonia lyase encoded by PAL2 from A. thaliana was constitutively expressed from a high copy plasmid. The final pathway step, phenylacrylate decarboxylase, was catalyzed by the native FDC1. Expression of FDC1 was naturally induced by trans-cinnamate, the pathway intermediate and its substrate, at levels sufficient for ensuring flux through the pathway. Deletion of ARO10 to eliminate the competing Ehrlich pathway and expression of a feedback-resistant DAHP synthase encoded by ARO4K229L preserved and promoted the endogenous availability precursor phenylalanine, leading to improved pathway flux and styrene production. These systematic improvements allowed styrene titers to ultimately reach 29 mg/L at a glucose yield of 1.44 mg/g, a 60% improvement over the initial strain. The potential of S. cerevisiae as a host for renewable styrene production has been demonstrated. Significant strain improvements, however, will ultimately be needed to achieve economical production levels.

Styrene exposure and risk of cancer

PubMed Central

Huff, James; Infante, Peter F.

2011-01-01

Styrene is widely used in the manufacture of synthetic rubber, resins, polyesters and plastics. Styrene and the primary metabolite styrene-7,8-oxide are genotoxic and carcinogenic. Long-term chemical carcinogenesis bioassays showed that styrene caused lung cancers in several strains of mice and mammary cancers in rats and styrene-7,8-oxide caused tumours of the forestomach in rats and mice and of the liver in mice. Subsequent epidemiologic studies found styrene workers had increased mortality or incidences of lymphohematopoietic cancers (leukaemia or lymphoma or all), with suggestive evidence for pancreatic and esophageal tumours. No adequate human studies are available for styrene-7,8-oxide although this is the primary and active epoxide metabolite of styrene. Both are genotoxic and form DNA adducts in humans. PMID:21724974

Roles of oxyanions in promoting the partial oxidation of styrene on Ag(110): nitrate, carbonate, sulfite, and sulfate.

PubMed

Zhou, Ling; Madix, Robert J

2010-11-02

The promotion roles of nitrate, carbonate, sulfite, and sulfate in oxidation of styrene on Ag(110) have been studied by means of temperature-programmed reaction spectroscopy (TPRS) and X-ray photoelectron spectroscopy (XPS). While isolated nitrate leads only to the secondary oxidation of styrene, a surface co-covered by nitrate, oxygen, and 0.1 ML cesium promotes a low-temperature epoxidation pathway. XPS indicates that adsorbed surface oxygen is the oxidant in this selective reaction pathway, and, though it affects the reactivity of the surface oxygen, nitrate is a spectator. Carbonate acts as an oxygen transfer agent and exhibits similar reactivity and selectivity as an oxidant for styrene as does atomic oxygen on Ag(110). The reactivities of sulfite and sulfate are strongly dependent on their surface structures, the c(6 × 2) sulfite showing the capacity to transfer oxygen to styrene.

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

Code of Federal Regulations, 2010 CFR

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...

Engineering of a Stable Whole-Cell Biocatalyst Capable of (S)-Styrene Oxide Formation for Continuous Two-Liquid-Phase Applications

PubMed Central

Panke, Sven; de Lorenzo, Víctor; Kaiser, Arnë; Witholt, Bernard; Wubbolts, Marcel G.

1999-01-01

Recombinant strains of Pseudomonas putida KT2440 carrying genetic expression cassettes with xylene oxygenase- and styrene monooxygenase-encoding genes on their chromosomes could be induced in shaking-flask experiments to specific activities that rivaled those of multicopy-plasmid-based Escherichia coli recombinants. Such strains maintained the introduced styrene oxidation activity in continuous two-liquid-phase cultures for at least 100 generations, although at a lower level than in the shaking-flask experiments. The data suggest that placement of target genes on the chromosome might be a suitable route for the construction of segregationally stable and highly active whole-cell biocatalysts. PMID:10584030

Enhancing productivity for cascade biotransformation of styrene to (S)-vicinal diol with biphasic system in hollow fiber membrane bioreactor.

PubMed

Gao, Pengfei; Wu, Shuke; Praveen, Prashant; Loh, Kai-Chee; Li, Zhi

2017-03-01

Biotransformation is a green and useful tool for sustainable and selective chemical synthesis. However, it often suffers from the toxicity and inhibition from organic substrates or products. Here, we established a hollow fiber membrane bioreactor (HFMB)-based aqueous/organic biphasic system, for the first time, to enhance the productivity of a cascade biotransformation with strong substrate toxicity and inhibition. The enantioselective trans-dihydroxylation of styrene to (S)-1-phenyl-1,2-ethanediol, catalyzed by Escherichia coli (SSP1) coexpressing styrene monooxygenase and an epoxide hydrolase, was performed in HFMB with organic solvent in the shell side and aqueous cell suspension in the lumen side. Various organic solvents were investigated, and n-hexadecane was found as the best for the HFMB-based biphasic system. Comparing to other reported biphasic systems assisted by HFMB, our system not only shield much of the substrate toxicity but also deflate the product recovery burden in downstream processing as the majority of styrene stayed in organic phase while the diol product mostly remained in the aqueous phase. The established HFMB-based biphasic system enhanced the production titer to 143 mM, being 16-fold higher than the aqueous system and 1.6-fold higher than the traditional dispersive partitioning biphase system. Furthermore, the combination of biphasic system with HFMB prevents the foaming and emulsification, thus reducing the burden in downstream purification. HFMB-based biphasic system could serve as a suitable platform for enhancing the productivity of single-step or cascade biotransformation with toxic substrates to produce useful and valuable chemicals.

SELECTIVE OXIDATION OF STYRENE TO ACETOPHENONE IN PRESENCE OF IONIC LIQUIDS

EPA Science Inventory

Palladium-catalyzed oxidation of styrene (Wacker reaction) in the presence of 1,3-dialkylimidazolium cation based ionic liquids is described. The effect of temperature, use of co-catalyst, and recyclability aspects for the generation of carbonyl compounds using environmentally de...

Depletion by styrene of glutathione in plasma and bronchioalveolar lavage fluid of non-Swiss albino (NSA) mice.

PubMed

Carlson, Gary P

2010-01-01

Styrene is a widely used chemical, but it is known to produce lung and liver damage in mice. This may be related to oxidative stress associated with the decrease in the levels of reduced glutathione (GSH) in the target tissues. The purpose of this study was to investigate the effect of styrene and its primary metabolites R-styrene oxide (R-SO) and S-styrene oxide (S-SO) on GSH levels in the lung lumen, as determined by amounts of GSH in bronchioalveolar lavage fluid (BALF) and in plasma. When non-Swiss albino (NSA) mice were administered styrene (600 mg/kg, ip), there was a significant fall in GSH levels in both BALF and plasma within 3 h. These returned to control levels by 12 h. The active metabolite R-SO (300 mg/kg, ip) also produced significant decreases in GSH in both BALF and plasma, but S-SO was without marked effect. Since GSH is a principal antioxidant in the lung epithelial lining fluid, this fall due to styrene may exert a significant influence on the ability of the lung to buffer oxidative damage.

Reaction of CO2 with propylene oxide and styrene oxide catalyzed by a chromium(III) amine-bis(phenolate) complex.

PubMed

Dean, Rebecca K; Devaine-Pressing, Katalin; Dawe, Louise N; Kozak, Christopher M

2013-07-07

A diamine-bis(phenolate) chromium(III) complex, {CrCl[O2NN'](BuBu)}2 catalyzes the copolymerization of propylene oxide with carbon dioxide. The synthesis of this metal complex is straightforward and it can be obtained in high yields. This catalyst incorporates a tripodal amine-bis(phenolate) ligand, which differs from the salen or salan ligands typically used with Cr and Co complexes that have been employed as catalysts for the synthesis of such polycarbonates. The catalyst reported herein yields low molecular weight polymers with narrow polydispersities when the reaction is performed at room temperature. Performing the reaction at elevated temperatures causes the selective synthesis of propylene carbonate. The copolymerization activity for propylene oxide and carbon dioxide, as well as the coupling of carbon dioxide and styrene oxide to give styrene carbonate are presented.

A FLUORESCENCE BASED ASSAY FOR DNA DAMAGE INDUCED BY STYRENE OXIDE

EPA Science Inventory

A rapid and simple assay to detect DNA damage to calf thymus DNA caused by styrene oxide (SO) is reported. This assay is based on changes observed in the melting and annealing behavior of the damaged DNA. The melting annealing process was monitored using a fluorescence indicat...

REDUCING STYRENE EMISSIONS FROM SPRAYED FILLED RESINS

EPA Science Inventory

Styrene emissions are coming under increasing study as the U.S. Environmental Protection Agency (EPA) develops maximum achievable control technology standards. During the manufacture of fiber-reinforced plastics/composites products, styrene, a volatile organic compound and a haz...

Enantioselective hydrolysis of racemic styrene oxide and its substituted derivatives using newly-isolated Sphingopyxis sp. exhibiting a novel epoxide hydrolase activity.

PubMed

Woo, Jung-Hee; Lee, Eun Yeol

2014-02-01

(S)-Styrene oxide, (S)-2-chlorostyrene oxide (CSO), (S)-3-CSO and (S)-4-CSO with 99.9 %ee were obtained with a yield of 20.6, 39.3, 28.7 and 26.8 % from 4 mM corresponding racemic substrates using 10 mg cells of a newly-isolated Sphingopyxis sp. at pH 8.0 and 25 °C in 1 ml 100 mM Tris/HCl buffer after 420, 100, 120 and 55 min, respectively. For racemic 2CSO, well-known for one of the racemates that is difficult to obtained in enantiomerically pure form, (S)-2-CSO with 99.9 %ee, 39.3 % yield (theoretical yield 50 %) and enantiomeric ratio of 42.1 was obtained. The newly-isolated strain can thus be used as whole-cell biocatalyst in the production of various (S)-CSO with a chlorine group at different positions.

Cooperative effects for CYP2E1 differ between styrene and its metabolites

PubMed Central

Hartman, Jessica H.; Boysen, Gunnar; Miller, Grover P.

2014-01-01

Cooperative interactions are frequently observed in the metabolism of drugs and pollutants by cytochrome P450s; nevertheless, the molecular determinants for cooperativity remain elusive. Previously, we demonstrated that steady-state styrene metabolism by CYP2E1 exhibits positive cooperativity.We hypothesized that styrene metabolites have lower affinity than styrene toward CYP2E1 and limited ability to induce cooperative effects during metabolism. To test the hypothesis, we determined the potency and mechanism of inhibition for styrene and its metabolites toward oxidation of 4-nitrophenol using CYP2E1 Supersomes® and human liver microsomes.Styrene inhibited the reaction through a mixed cooperative mechanism with high affinity for the catalytic site (67 μM) and lower affinity for the cooperative site (1100 μM), while increasing substrate turnover at high concentrations. Styrene oxide and 4-vinylphenol possessed similar affinity for CYP2E1. Styrene oxide behaved cooperatively like styrene, but 4-vinylphenol decreased turnover at high concentrations. Styrene glycol was a very poor competitive inhibitor. Among all compounds, there was a positive correlation with binding and hydrophobicity.Taken together, these findings for CYP2E1 further validate contributions of cooperative mechanisms to metabolic processes, demonstrate the role of molecular structure on those mechanisms and underscore the potential for heterotropic cooperative effects between different compounds. PMID:23327532

Synthesis of cobalt-containing mesoporous catalysts using the ultrasonic-assisted “pH-adjusting” method: Importance of cobalt species in styrene oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Baitao, E-mail: btli@scut.edu.cn; Zhu, Yanrun; Jin, Xiaojing

2015-01-15

Cobalt-containing SBA-15 and MCM-41 (Co-SBA-15 and Co-MCM-41) mesoporous catalysts were prepared via ultrasonic-assisted “pH-adjusting” technique in this study. Their physiochemical structures were comprehensively characterized and correlated with catalytic activity in oxidation of styrene. The nature of cobalt species depended on the type of mesoporous silica as well as pH values. The different catalytic performance between Co-SBA-15 and Co-MCM-41 catalysts originated from cobalt species. Cobalt species were homogenously incorporated into the siliceous framework of Co-SBA-15 in single-site Co(II) state, while Co{sub 3}O{sub 4} particles were loaded on Co-MCM-41 catalysts. The styrene oxidation tests showed that the single-site Co(II) state was moremore » beneficial to the catalytic oxidation of styrene. The higher styrene conversion and benzaldehyde selectivity over Co-SBA-15 catalysts were mainly attributed to single-site Co(II) state incorporated into the framework of SBA-15. The highest conversion of styrene (34.7%) with benzaldehyde selectivity of 88.2% was obtained over Co-SBA-15 catalyst prepared at pH of 7.5, at the mole ratio of 1:1 (styrene to H{sub 2}O{sub 2}) at 70 °C. - Graphical abstract: Cobalt-containing mesoporous silica catalysts were developed via ultrasonic-assisted “pH-adjusting” technique. Compared with Co{sub 3}O{sub 4} in Co-MCM-41, the single-site Co(II) state in Co-SBA-15 was more efficient for the styrene oxidation. - Highlights: • Fast and cost-effective ultrasonic technique for preparing mesoporous materials. • Incorporation of Co via ultrasonic irradiation and “pH-adjusting”. • Physicochemical comparison between Co-SBA-15 and Co-MCM-41. • Correlation of styrene oxidation activity and catalyst structural property.« less

Assessment of Styrene Oxide Neurotoxicity Using In Vitro Auditory Cortex Networks

PubMed Central

Gopal, Kamakshi V.; Wu, Calvin; Moore, Ernest J.; Gross, Guenter W.

2011-01-01

Styrene oxide (SO) (C8H8O), the major metabolite of styrene (C6H5CH=CH2), is widely used in industrial applications. Styrene and SO are neurotoxic and cause damaging effects on the auditory system. However, little is known about their concentration-dependent electrophysiological and morphological effects. We used spontaneously active auditory cortex networks (ACNs) growing on microelectrode arrays (MEA) to characterize neurotoxic effects of SO. Acute application of 0.1 to 3.0 mM SO showed concentration-dependent inhibition of spike activity with no noticeable morphological changes. The spike rate IC50 (concentration inducing 50% inhibition) was 511 ± 60 μM (n = 10). Subchronic (5 hr) single applications of 0.5 mM SO also showed 50% activity reduction with no overt changes in morphology. The results imply that electrophysiological toxicity precedes cytotoxicity. Five-hour exposures to 2 mM SO revealed neuronal death, irreversible activity loss, and pronounced glial swelling. Paradoxical “protection” by 40 μM bicuculline suggests binding of SO to GABA receptors. PMID:23724250

Studies of styrene, styrene oxide and 4-hydroxystyrene toxicity in CYP2F2 knockout and CYP2F1 humanized mice support lack of human relevance for mouse lung tumors.

PubMed

Cruzan, G; Bus, J; Hotchkiss, J; Sura, R; Moore, C; Yost, G; Banton, M; Sarang, S

2013-06-01

Styrene (S) is lung tumorigenic in mice but not in rats. S and its alkene-oxidized metabolite styrene oxide (SO) were not lung toxic in CYP2F2(-/-) [knockout] mice, indicating S-induced mouse lung tumors are mediated through mouse-specific CYP2F2-generated ring-oxidized metabolite(s) in lung bronchioles. The human relevance of the CYP2F MOA was assessed by insertion of a human CYP2F1, 2A13, 2B6 transgene into CYP2F2(-/-) mice; CYP2F1 expression and activity were confirmed in the transgenic (TG) mice. No evidence of cytotoxicity or increased cell proliferation (BrdU labeling) was seen in TG mice treated with either S or SO (200mg/kg/day ip for 5days). In contrast to S and SO, 4HS (105mg/kg/day ip for 5days) increased BrdU labeling 5-10-fold in WT mice, <3-fold increase in KO mice and 2-4-fold in TG mice. The limited response of 4HS in KO and TG mice may result from intrinsic toxicity or from further metabolism; regardless of the MOA, these findings indicate that the CYP2F-mediated tumorigenic MOA in WT mice is not operative for S, SO, or for 4HS putatively derived from metabolism of S by CYP2F1 in humans, and thus S-induced mouse lung tumors are unlikely to be relevant to human risk. Copyright © 2013. Published by Elsevier Inc.

Calcium oxide supported gold nanoparticles as catalysts for the selective epoxidation of styrene by t-butyl hydroperoxide.

PubMed

Dumbre, Deepa K; Choudhary, Vasant R; Patil, Nilesh S; Uphade, Balu S; Bhargava, Suresh K

2014-02-01

Gold nanoparticles are deposited on basic CaO supports as catalysts for the selective conversion of styrene into styrene oxide. Synthetic methods, gold loading and calcination temperatures are varied to permit an understanding of their influence on gold nanoparticle size, the presence of cationic gold species and the nature of interaction between the gold nanoparticles and the CaO support. Based on these studies, optimal conditions are designed to make the Au/CaO catalyst efficient for the selective epoxidation of styrene. Copyright © 2013 Elsevier Inc. All rights reserved.

Reversal of enantioselectivity in the hydroformylation of styrene with [2S,4S-BDPP]Pt(SnCl3)Cl at high temperature arises from a change in the enantioselective-determining step.

PubMed

Casey, Charles P; Martins, Susie C; Fagan, Maureen A

2004-05-05

Deuterioformylation of styrene catalyzed by [(2S,4S)-BDPP]Pt(SnCl(3))Cl at 39 degrees C gave 3-phenylpropanal (3) and 2-phenylpropanal (2) (n:i = 1.8, 71% ee (S)-2) with deuterium only beta to the aldehyde carbonyl and in the formyl group. Small amounts of deuterium were also found in the internal (2.8%), cis terminal (1.4%), and trans terminal (1.3%) vinyl positions of the recovered styrene. Deuterioformylation of styrene at 98 degrees C gave 3- (3) and 2-phenylpropanal (2) (n:i = 2.3, 10% ee (R)-2) with deuterium both alpha and beta to the aldehyde carbonyl and in the formyl group. Deuterium was also found in the internal (20%), cis terminal (12%), and trans terminal (12%) vinyl positions of the recovered styrene. These deuterioformylation results establish that platinum hydride addition to styrene is largely irreversible at 39 degrees C but reversible at 98 degrees C. Hydroformylation of (E)- and (Z)-beta-deuteriostyrene at 40 degrees C, followed by oxidation of the aldehydes to acids, and subsequent derivitization to the (S)-mandelate esters confirmed that 84% of 2-phenylpropanal (2) arises from platinum hydride addition to the si-face of styrene, while 73% of 3-phenylpropanal (3) arises from platinum hydride addition to the re-face of styrene. At 100 degrees C, the effect of variable H(2) and CO pressure on n:i, % ee, and TOF of hydroformylation of styrene was investigated. The results are consistent with enantioselectivity not being fully determined until the final hydrogenolysis of a platinum acyl intermediate.

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

PubMed

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.

Viscoelastic Properties, Ionic Conductivity, and Materials Design Considerations for Poly(styrene-b-ethylene oxide-b-styrene)-Based Ion Gel Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Sipei; Lee, Keun Hyung; Sun, Jingru

2013-03-07

The viscoelastic properties and ionic conductivity of ion gels based on the self-assembly of a poly(styrene-b-ethylene oxide-b-styrene) (SOS) triblock copolymer (M{sub n,S} = 3 kDa, M{sub n,O} = 35 kDa) in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMI][TFSA]) were investigated over the composition range of 10-50 wt % SOS and the temperature range of 25-160 C. The poly(styrene) (PS) end-blocks associate into micelles, whereas the poly(ethylene oxide) (PEO) midblocks are well-solvated by this ionic liquid. The ion gel with 10 wt % SOS melts at 54 C, with the longest relaxation time exhibiting a similar temperature dependence to that of themore » viscosity of bulk PS. However, the actual values of the gel relaxation time are more than 4 orders of magnitude larger than the relaxation time of bulk PS. This is attributed to the thermodynamic penalty of pulling PS end-blocks through the PEO/[EMI][TFSA] matrix. Ion gels with 20-50 wt % SOS do not melt and show two plateaus in the storage modulus over the temperature and frequency ranges measured. The one at higher frequencies is that of an entangled network of PEO strands with PS cross-links; the modulus displays a quadratic dependence on polymer weight fraction and agrees with the prediction of linear viscoelastic theory assuming half of the PEO chains are elastically effective. The frequency that separates the two plateaus, {omega}{sub c}, reflects the time scale of PS end-block pull-out. The other plateau at lower frequencies is that of a congested micelle solution with PS cores and PEO coronas, which has a power law dependence on domain spacing similar to diblock melts. The ionic conductivity of the ion gels is compared to PEO homopolymer solutions at similar polymer concentrations; the conductivity is reduced by a factor of 2.1 or less, decreases with increasing PS volume fraction, and follows predictions based on a simple obstruction model. Our collective results allow the

Biomarkers of early genotoxicity and oxidative stress for occupational risk assessment of exposure to styrene in the fibreglass reinforced plastic industry.

PubMed

Cavallo, Delia; Tranfo, Giovanna; Ursini, Cinzia Lucia; Fresegna, Anna Maria; Ciervo, Aureliano; Maiello, Raffaele; Paci, Enrico; Pigini, Daniela; Gherardi, Monica; Gatto, Maria Pia; Buresti, Giuliana; Iavicoli, Sergio

2018-06-10

This study aimed to identify sensitive and not-invasive biomarkers of early genotoxic/oxidative effect for exposure to styrene in the fibreglass reinforced plastic manufacture. We studied 11 workers of a plastic manufacture using open molding process (A), 16 workers of a manufacture using closed process (B) and 12 controls. We evaluated geno/cytotoxic effects on buccal cells by Buccal Micronucleus Cytome (BMCyt) assay and genotoxic/oxidative effects on lymphocytes by Fpg-comet test. On A workers we also evaluated urinary 8oxoGua, 8oxodGuo and 8oxoGuo to investigate oxidative stress. Personal inhalation exposure to styrene was monitored by passive air sampling and GC/MS. Biological monitoring included urinary metabolites mandelic acid (MA) and phenylglyoxylic acid (PGA). The findings show higher styrene exposure, urinary MA + PGA levels and micronucleus frequency in manufacture A. Higher buccal karyolytic cell frequency vs controls were found in both exposed populations. We found in exposed workers, no induction of direct DNA damage but oxidative DNA damage. Fpg-comet assay and urinary oxidized guanine seem to be sensitive biomarkers of oxidative stress and BMCyt assay a good-not invasive biomarker of cyto-genotoxicity at target organ. The study, although limited by the small number of studied subjects, shows the usefulness of used biomarkers in risk assessment of styrene-exposed workers. Copyright © 2018 Elsevier B.V. All rights reserved.

PALLADIUM-CATALYZED OXIDATION OF STYRENE AND ALKENES IN PRESENCE OF IONIC LIQUIDS (WACKER REACTION)

EPA Science Inventory

The use of ionic liquids in various synthetic transformations is gaining significance due to the enhanced reaction rates, potential for recycling and compatibility with various organic compounds and organometallic catalysts. Palladium-catalyzed oxidation of styrene and other alk...

Origin of pressure effects on regioselectivity and enantioselectivity in the rhodium-catalyzed hydroformylation of styrene with (S,S,S)-BisDiazaphos.

PubMed

Watkins, Avery L; Landis, Clark R

2010-08-04

Gas pressure influences the regioselectivity and enantioselectivity of aryl alkene hydroformylation as catalyzed by rhodium complexes of the BisDiazaphos ligand. Deuterioformylation of styrene at 80 degrees C results in extensive deuterium incorporation into the terminal position of the recovered styrene. This result establishes that rhodium hydride addition to form a branched alkyl rhodium occurs reversibly. The independent effect of carbon monoxide and hydrogen partial pressures on regioselectivity and enantioselectivity were measured. From 40 to 120 psi, both regioisomer (b:l) and enantiomer (R:S) ratios are proportional to the carbon monoxide partial pressure but approximately independent of the hydrogen pressure. The absolute rate for linear aldehyde formation was found to be inhibited by carbon monoxide pressure, whereas the rate for branched aldehyde formation is independent of CO pressure up to 80 psi; above 80 psi one observes the onset of inhibition. The carbon monoxide dependence of the rate and enantioselectivity for branched aldehyde indicates that the rate of production of (S)-2-phenyl propanal is inhibited by CO pressure, while the formation rate of the major enantiomer, (R)-2-phenyl propanal, is approximately independent of CO pressure. Hydroformylation of alpha-deuteriostyrene at 80 degrees C followed by conversion to (S)-2-benzyl-4-nitrobutanal reveals that 83% of the 2-phenylpropanal resulted from rhodium hydride addition to the re face of styrene, and 83% of the 3-phenylpropanal resulted from rhodium hydride addition to the si face of styrene. On the basis of these results, kinetic and steric/electronic models for the determination of regioselectivity and enantioselectivity are proposed.

Conversion Characteristics and Production Evaluation of Styrene/o-Xylene Mixtures Removed by DBD Pretreatment

PubMed Central

Jiang, Liying; Zhu, Runye; Mao, Yubo; Chen, Jianmeng; Zhang, Liang

2015-01-01

The combination of chemical oxidation methods with biotechnology to removal recalcitrant VOCs is a promising technology. In this paper, the aim was to identify the role of key process parameters and biodegradability of the degradation products using a dielectric barrier discharge (DBD) reactor, which provided the fundamental data to evaluate the possibilities of the combined system. Effects of various technologic parameters like initial concentration of mixtures, residence time and relative humidity on the decomposition and the degradation products were examined and discussed. It was found that the removal efficiency of mixed VOCs decreased with increasing initial concentration. The removal efficiency reached the maximum value as relative humidity was approximately 40%–60%. Increasing the residence time resulted in increasing the removal efficiency and the order of destruction efficiency of VOCs followed the order styrene > o-xylene. Compared with the single compounds, the removal efficiency of styrene and o-xylene in the mixtures of VOCs decreased significantly and o-xylene decreased more rapidly. The degradation products were analyzed by gas chromatography and gas chromatography-mass spectrometry, and the main compounds detected were O3, COx and benzene ring derivatives. The biodegradability of mixed VOCs was improved and the products had positive effect on biomass during plasma application, and furthermore typical results indicated that the biodegradability and biotoxicity of gaseous pollutant were quite depending on the specific input energy (SIE). PMID:25629961

Genotoxic effects of styrene-7,8-oxide in human white blood cells: comet assay in relation to the induction of sister-chromatid exchanges and micronuclei.

PubMed

Laffon, B; Pásaro, E; Méndez, J

2001-04-05

Styrene is used in the production of plastics, resins and rubber. The highest human exposures to styrene take place by inhalation during the production of fiberglass reinforced plastics. Styrene is metabolized mainly in the liver to styrene-7,8-oxide (SO), its principal in vivo mutagenic metabolite. In this study, human peripheral white blood cells were exposed to several SO concentrations (10-200 microM) in order to evaluate its genotoxic properties by means of comet assay, sister-chromatid exchanges (SCE) and cytokinesis-blocked micronucleus (MN) test, in addition to determine its clastogenic or aneugenic properties by combining MN with fluorescence in situ hybridization (FISH) procedures. Our results show that SO induces DNA damage, SCE and MN in human leukocytes in vitro at concentrations above 50 microM, and that there is a strong relationship between DNA damage, as measured by the comet assay, and cytogenetic damage induced by SO at the doses employed. SO shows preferentially a clastogenic activity and produces a cytostatic effect at high doses, reflected by the significant decrease of the calculated proliferation indices. A good dose-effect relationship is obtained in the three tests performed at the concentration range assayed.

CYP2E1 Metabolism of Styrene Involves Allostery

PubMed Central

Hartman, Jessica H.; Boysen, Gunnar

2012-01-01

We are the first to report allosterism during styrene oxidation by recombinant CYP2E1 and human liver microsomes. At low styrene concentrations, oxidation is inefficient because of weak binding to CYP2E1 (Ks = 830 μM). A second styrene molecule then binds CYP2E1 with higher affinity (Kss = 110 μM) and significantly improves oxidation to achieve a kcat of 6.3 nmol · min−1 · nmol CYP2E1−1. The transition between these metabolic cycles coincides with reported styrene concentrations in blood from exposed workers; thus, this CYP2E1 mechanism may be relevant in vivo. Scaled modeling of the in vitro-positive allosteric mechanism for styrene metabolism to its in vivo clearance led to significant deviations from the traditional model based on Michaelis-Menten kinetics. Low styrene levels were notably much less toxic than generally assumed. We interrogated the allosteric mechanism using the CYP2E1-specific inhibitor and drug 4-methylpyrazole, which we have shown binds two CYP2E1 sites. From the current studies, styrene was a positive allosteric effector on 4-methylpyrazole binding, based on a 10-fold increase in 4-methylpyrazole binding affinity from Ki 0.51 to Ksi 0.043 μM. The inhibitor was a negative allosteric effector on styrene oxidation, because kcat decreased 6-fold to 0.98 nmol · min−1 · nmol CYP2E1−1. Consequently, mixtures of styrene and other molecules can induce allosteric effects on binding and metabolism by CYP2E1 and thus mitigate the efficiency of their metabolism and corresponding effects on human health. Taken together, our elucidation of mechanisms for these allosteric reactions provides a powerful tool for further investigating the complexities of CYP2E1 metabolism of drugs and pollutants. PMID:22807108

Mesoporous xEr 2O 3·CoTiO 3 composite oxide catalysts for low temperature dehydrogenation of ethylbenzene to styrene using CO 2 as a soft oxidant

DOE PAGES

Yue, Yanfeng; Zhang, Li; Chen, Jihua; ...

2016-01-01

A series of mesoporous xEr 2O 3·CoTiO 3 composite oxide catalysts have been prepared using template method and tested as a new type of catalyst for the oxidative dehydrogenation of ethylbenzene to styrene by using CO 2 as a soft oxidant. Among the catalysts tested, the 0.25Er 2O 3 CoTiO 3 sample with a ratio of 1:4:4 content and calcined at 600 oC exhibited the highest ethylbenzene conversion (58%) and remarkable styrene selectivity (95%) at low temperature (450 °C).

Gold-catalysed oxyarylation of styrenes and mono- and gem-disubstituted olefins facilitated by an iodine(III) oxidant.

PubMed

Ball, Liam T; Lloyd-Jones, Guy C; Russell, Christopher A

2012-03-05

1-Hydroxy-1,2-benziodoxol-3(1H)-one (IBA) is an efficient terminal oxidant for gold-catalysed, three-component oxyarylation reactions. The use of this iodine(III) reagent expands the scope of oxyarylation to include styrenes and gem-disubstituted olefins, substrates that are incompatible with the previously reported Selectfluor-based methodology. Diverse arylsilane coupling partners can be employed, and in benzotrifluoride, homocoupling is substantially reduced. In addition, the IBA-derived co-products can be recovered and recycled. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of graphene oxide/poly (3,4-ethylenedioxytriophene): Poly (styrene sulfonate) (PEDOT:PSS) electrospun nanofibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Efelina, Vita; Widianto, Eri; Rusdiana, Dadi

2016-04-19

Graphene oxide (GO)/Poly (3,4-Ethylenedioxytriophene):Poly (styrene Sulfonate) (PEDOT:PSS) nanofibers have been successfully fabricated by a simple electrospinning technique to develop conductive nanofibers with polyvinyl alcohol (PVA) act as a carrier solution. Graphene oxide has been synthesized by Hummer’s method and has been confirmed by Raman Spectroscopy, FTIR and UV-Vis Spectroscopy. GO/PEDOT:PSS composite nanofibers. The structural and morphological properties were characterized by Scanning Electron Microscopy (SEM). The result of SEM show that GO/PEDOT:PSS nanofibers has a relatively uniform morphology nanofiber with diameter between 180 nm - 340 nm with smooth nanofiber surface. The produced nanofibers from this study can be utilized for various applicationsmore » such as flexible, conductive and transparent electrode.« less

The role of CO 2 as a soft oxidant for dehydrogenation of ethylbenzene to styrene over a high-surface-area ceria catalyst

DOE PAGES

Zhang, Li; Wu, Zili; Nelson, Nicholas; ...

2015-09-22

Catalytic performance and the nature of surface adsorbates were investigated for high-surface-area ceria during ethylbenzene oxidative dehydrogenation (ODH) reaction using CO2 as a soft oxidant. A template assisted method was used to synthesize the high-surface-area ceria. The interactions between ethylbenzene, styrene and CO2 on the surface of ceria and the role of CO2 for the ethylbenzene ODH reaction have been investigated in detail by using activity test, in situ Diffuse Reflectance Infrared and Raman spectroscopy. Not only did CO2 as an oxidant favor the higher yield of styrene, but it also inhibited the deposition of coke during the ethylbenzene ODHmore » reaction. Ethylbenzene ODH reaction over ceria followed a two-step pathway: Ethylbenzene is first dehydrogenated to styrene with H2 formed simultaneously, and then CO2 reacts with H2 via the reverse water gas shift. The styrene produced can easily polymerize to form polystyrene, a key intermediate for coke formation. In the absence of CO2, the polystyrene transforms into graphite-like coke at temperatures above 500 °C, which leads to catalyst deactivation. While in the presence of CO2, the coke deposition can be effectively removed via oxidation with CO2.« less

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

Code of Federal Regulations, 2010 CFR

2010-07-01

... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... 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...

Structure and Ligand Binding Properties of the Epoxidase Component of Styrene Monooxygenase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ukaegbu, Uchechi E.; Kantz, Auric; Beaton, Michelle

2010-07-23

Styrene monooxygenase (SMO) is a two-component flavoprotein monooxygenase that transforms styrene to styrene oxide in the first step of the styrene catabolic and detoxification pathway of Pseudomonas putida S12. The crystal structure of the N-terminally histidine-tagged epoxidase component of this system, NSMOA, determined to 2.3 {angstrom} resolution, indicates the enzyme exists as a homodimer in which each monomer forms two distinct domains. The overall architecture is most similar to that of p-hydroxybenzoate hydroxylase (PHBH), although there are some significant differences in secondary structure. Structural comparisons suggest that a large cavity open to the surface forms the FAD binding site. Atmore » the base of this pocket is another cavity that likely represents the styrene binding site. Flavin binding and redox equilibria are tightly coupled such that reduced FAD binds apo NSMOA {approx}8000 times more tightly than the oxidized coenzyme. Equilibrium fluorescence and isothermal titration calorimetry data using benzene as a substrate analogue indicate that the oxidized flavin and substrate analogue binding equilibria of NSMOA are linked such that the binding affinity of each is increased by 60-fold when the enzyme is saturated with the other. A much weaker {approx}2-fold positive cooperative interaction is observed for the linked binding equilibria of benzene and reduced FAD. The low affinity of the substrate analogue for the reduced FAD complex of NSMOA is consistent with a preferred reaction order in which flavin reduction and reaction with oxygen precede the binding of styrene, identifying the apoenzyme structure as the key catalytic resting state of NSMOA poised to bind reduced FAD and initiate the oxygen reaction.« less

Development of a Novel Escherichia coli–Kocuria Shuttle Vector Using the Cryptic pKPAL3 Plasmid from K. palustris IPUFS-1 and Its Utilization in Producing Enantiopure (S)-Styrene Oxide

PubMed Central

Toda, Hiroshi; Itoh, Nobuya

2017-01-01

The novel cryptic pKPAL3 plasmid was isolated from the Gram-positive microorganism Kocuria palustris IPUFS-1 and characterized in detail. pKPAL3 is a circular plasmid that is 4,443 bp in length. Open reading frame (ORF) and homology search analyses indicated that pKPAL3 possesses four ORFs; however, there were no replication protein coding genes predicted in the plasmid. Instead, there were two nucleotide sequence regions that showed significant identities with untranslated regions of K. rhizophila DC2201 (NBRC 103217) genomic sequences, and these sequences were essential for autonomous replication of pKPAL3 in Kocuria cells. Based on these findings, we constructed the novel Escherichia coli–Kocuria shuttle vectors pKITE301 (kanamycin resistant) and pKITE303 (thiostrepton resistant) from pKPAL3. The copy numbers of the constructed shuttle vectors were estimated to be 20 per cell, and they exhibited low segregation stability in Kocuria transformant cells in the absence of antibiotics. Moreover, constructed vectors showed compatibility with the other K. rhizophila shuttle vector pKITE103. We successfully expressed multiple heterologous genes, including the styrene monooxygenase gene from Rhodococcus sp. ST-10 (rhsmo) and alcohol dehydrogenase gene from Leifsonia sp. S749 (lsadh), in K. rhizophila DC2201 using the pKITE301P and pKITE103P vectors under the control of the glyceraldehyde 3-phosphate dehydrogenase (gapdh) promotor. The RhSMO–LSADH co-expressing K. rhizophila was used as a biocatalyst in an organic solvent–water biphasic reaction system to efficiently convert styrene into (S)-styrene oxide with 99% ee in the presence of 2-propanol as a hydrogen donor. The product concentration of the reaction in the organic solvent reached 235 mM after 30 h under optimum conditions. Thus, we demonstrated that this novel shuttle vector is useful for developing biocatalysts based on organic solvent-tolerant Kocuria cells. PMID:29230202

Development of a Novel Escherichia coli-Kocuria Shuttle Vector Using the Cryptic pKPAL3 Plasmid from K. palustris IPUFS-1 and Its Utilization in Producing Enantiopure (S)-Styrene Oxide.

PubMed

Toda, Hiroshi; Itoh, Nobuya

2017-01-01

The novel cryptic pKPAL3 plasmid was isolated from the Gram-positive microorganism Kocuria palustris IPUFS-1 and characterized in detail. pKPAL3 is a circular plasmid that is 4,443 bp in length. Open reading frame (ORF) and homology search analyses indicated that pKPAL3 possesses four ORFs; however, there were no replication protein coding genes predicted in the plasmid. Instead, there were two nucleotide sequence regions that showed significant identities with untranslated regions of K. rhizophila DC2201 (NBRC 103217) genomic sequences, and these sequences were essential for autonomous replication of pKPAL3 in Kocuria cells. Based on these findings, we constructed the novel Escherichia coli - Kocuria shuttle vectors pKITE301 (kanamycin resistant) and pKITE303 (thiostrepton resistant) from pKPAL3. The copy numbers of the constructed shuttle vectors were estimated to be 20 per cell, and they exhibited low segregation stability in Kocuria transformant cells in the absence of antibiotics. Moreover, constructed vectors showed compatibility with the other K. rhizophila shuttle vector pKITE103. We successfully expressed multiple heterologous genes, including the styrene monooxygenase gene from Rhodococcus sp. ST-10 ( rhsmo ) and alcohol dehydrogenase gene from Leifsonia sp. S749 ( lsadh ), in K . rhizophila DC2201 using the pKITE301P and pKITE103P vectors under the control of the glyceraldehyde 3-phosphate dehydrogenase ( gapdh ) promotor. The RhSMO-LSADH co-expressing K. rhizophila was used as a biocatalyst in an organic solvent-water biphasic reaction system to efficiently convert styrene into ( S )-styrene oxide with 99% ee in the presence of 2-propanol as a hydrogen donor. The product concentration of the reaction in the organic solvent reached 235 mM after 30 h under optimum conditions. Thus, we demonstrated that this novel shuttle vector is useful for developing biocatalysts based on organic solvent-tolerant Kocuria cells.

Comparison of mouse strains for susceptibility to styrene-induced hepatotoxicity and pneumotoxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, G.P.

1997-10-01

Styrene is known to cause both hepatotoxicity and pneumotoxicity in mice. Strain differences have been reported by other investigators suggesting that Swiss mice are less susceptible than non-Swiss mice to styrene-induced liver damage. In this study, All and C57BL16 mice were found to be similar to non-Swiss albino (NSA) mice in susceptibility whereas CD-1 (Swiss) mice were more resistant to hepatotoxicity as assessed by serum sorbitol dehydrogenase levels and pneumotoxicity as determined by gamma-glutamyltranspeptidase and lactate dehydrogenase measurements in bronchoalveolar ravage fluid. Styrene was hepatotoxic in CD-1 mice treated with pyridine to induce CYP2E1. CYP2E1 apoprotein levels and p-nitrophenol hydroxylasemore » activities in control and pyridine-induced mice were similar in the two strains. Hepatic and pulmonary microsomal preparations from both strains metabolized styrene to styrene oxide at similar rates. CD-1 mice were as susceptible as the NSA mice to the effects of styrene oxide. The data suggest that there are no differences in the bioactivation of styrene to styrene oxide or innate susceptibility to the active metabolite that would account for the differences between the CD-1 and NSA mice. 26 refs., 6 tabs.« less

Organic chemistry. A rhodium catalyst for single-step styrene production from benzene and ethylene.

PubMed

Vaughan, Benjamin A; Webster-Gardiner, Michael S; Cundari, Thomas R; Gunnoe, T Brent

2015-04-24

Rising global demand for fossil resources has prompted a renewed interest in catalyst technologies that increase the efficiency of conversion of hydrocarbons from petroleum and natural gas to higher-value materials. Styrene is currently produced from benzene and ethylene through the intermediacy of ethylbenzene, which must be dehydrogenated in a separate step. The direct oxidative conversion of benzene and ethylene to styrene could provide a more efficient route, but achieving high selectivity and yield for this reaction has been challenging. Here, we report that the Rh catalyst ((Fl)DAB)Rh(TFA)(η(2)-C2H4) [(Fl)DAB is N,N'-bis(pentafluorophenyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene; TFA is trifluoroacetate] converts benzene, ethylene, and Cu(II) acetate to styrene, Cu(I) acetate, and acetic acid with 100% selectivity and yields ≥95%. Turnover numbers >800 have been demonstrated, with catalyst stability up to 96 hours. Copyright © 2015, American Association for the Advancement of Science.

The structure of a one-electron oxidized Mn(iii)-bis(phenolate)dipyrrin radical complex and oxidation catalysis control via ligand-centered redox activity.

PubMed

Lecarme, Laureline; Chiang, Linus; Moutet, Jules; Leconte, Nicolas; Philouze, Christian; Jarjayes, Olivier; Storr, Tim; Thomas, Fabrice

2016-10-18

The tetradentate ligand dppH3, which features a half-porphyrin and two electron-rich phenol moieties, was prepared and chelated to manganese. The mononuclear Mn(iii)-dipyrrophenolate complex 1 was structurally characterized. The metal ion lies in a square pyramidal environment, the apical position being occupied by a methanol molecule. Complex 1 displays two reversible oxidation waves at 0.00 V and 0.47 V vs. Fc + /Fc, which are assigned to ligand-centered processes. The one-electron oxidized species 1+ SbF6- was crystallized, showing an octahedral Mn(iii) center with two water molecules coordinated at both apical positions. The bond distance analysis and DFT calculations disclose that the radical is delocalized over the whole aromatic framework. Complex 1+ SbF6- exhibits an S tot = 3/2 spin state due to the antiferromagnetic coupling between Mn(iii) and the ligand radical. The zero field splitting parameters are D = 1.6 cm -1 , E/D = 0.18(1), g ⊥ = 1.99 and g ∥ = 1.98. The dication 12+ is an integer spin system, which is assigned to a doubly oxidized ligand coordinated to a Mn(iii) metal center. Both 1 and 1+ SbF6- catalyze styrene oxidation in the presence of PhIO, but the nature of the main reaction product is different. Styrene oxide is the main reaction product when using 1, but phenylacetaldehyde is formed predominantly when using 1+ SbF6-. We examined the ability of complex 1+ SbF6- to catalyze the isomerization of styrene oxide and found that it is an efficient catalyst for the anti-Markovnikov opening of styrene oxide. The formation of phenylacetaldehyde from styrene therefore proceeds in a tandem E-I (epoxidation-isomerization) mechanism in the case of 1+ SbF6-. This is the first evidence of control of the reactivity for styrene oxidation by changing the oxidation state of a catalyst based on a redox-active ligand.

Engineering Styrene Monooxygenase for Biocatalysis: Reductase-Epoxidase Fusion Proteins.

PubMed

Heine, Thomas; Tucker, Kathryn; Okonkwo, Nonye; Assefa, Berhanegebriel; Conrad, Catleen; Scholtissek, Anika; Schlömann, Michael; Gassner, George; Tischler, Dirk

2017-04-01

The enantioselective epoxidation of styrene and related compounds by two-component styrene monooxygenases (SMOs) has targeted these enzymes for development as biocatalysts. In the present work, we prepare genetically engineered fusion proteins that join the C-terminus of the epoxidase (StyA) to the N-terminus of the reductase (StyB) through a linker peptide and demonstrate their utility as biocatalysts in the synthesis of Tyrain purple and other indigoid dyes. A single-vector expression system offers a simplified platform for transformation and expansion of the catalytic function of styrene monooxygenases, and the resulting fusion proteins are self-regulated and couple efficiently NADH oxidation to styrene epoxidation. We find that the reductase domain proceeds through a sequential ternary-complex mechanism at low FAD concentration and a double-displacement mechanism at higher concentrations of FAD. Single-turnover studies indicate an observed rate constant for FAD-to-FAD hydride transfer of ~8 s -1 . This step is rate limiting in the styrene epoxidation reaction and helps to ensure that flavin reduction and styrene epoxidation reactions proceed without wasteful side reactions. Comparison of the reductase activity of the fusion proteins with the naturally occurring reductase, SMOB, and N-terminally histidine-tagged reductase, NSMOB, suggests that the observed changes in catalytic mechanism are due in part to an increase in flavin-binding affinity associated with the N-terminal extension of the reductase.

Structure-toxicity relationship study of para-halogenated styrene analogues in CYP2E1 transgenic cells

PubMed Central

Chung, Jou-Ku; Shen, Shuijie; Jiang, Zhiteng; Yuan, Wei; Zheng, Jiang

2012-01-01

Styrene is one of the most important industrial intermediates consumed in the world and is mainly used as a monomer for reinforced plastics and rubber. Styrene has been found to be hepatotoxic and pneumotoxic in humans and experimental animals. The toxicity of styrene is suggested to be metabolism-dependent. Styrene-7,8-oxide has been considered as the major metabolite responsible for styrene-induced cytotoxicity. The objective of the study was to investigate the correlation between cytotoxicity of styrene and chemical and biochemical properties of the vinyl group of styrene by development of structure activity relationships (SAR). 4-Fluorostyrene, 4-chlorostyrene and 4-bromostyrene were selected for the SAR study. Cytotoxicity of styrene and the halogenated styrene derivatives with an order of 4-bromostyrene > 4-chlorostyrene > 4-fluorostyrene ≈ styrene was observed in CYP2E1 transgenic cells. Similar orders in the efficiency of the metabolism of styrene and the halogenated styrene analogues to their oxides and in the electrophilicity of the corresponding oxides were observed. Additionally, the order of the potency of cellular glutathione depletion and the degree of protein adduction induced by styrene and the halogenated styrenes were consistent with that of their cytotoxicities. The wild-type cells were less susceptible to the toxicity of the corresponding model compounds than CYP2E1 cells. The present study provided insight into the roles of the biochemical and chemical properties of styrene in its cytotoxicity. PMID:22366341

Heat resistant polymers of oxidized styrylphosphine

NASA Technical Reports Server (NTRS)

Paciorek, K. J. L. (Inventor)

1978-01-01

Homopolymers, copolymers and terpolymers of a styrene based monomer are prepared by polymerizing at least one oxidized styrylphosphine monomer or by polymerizing p-diphenylphosphinestyrene and then oxidizing the polymerized monomer with an organoazide. Copolymers can also be prepared by copolymerizing styrene with at least one oxidized styrylphosphine monomer. Flame resistant vinyl based polymers whose degradation products are non toxic and non corrosive are obtained.

Copper-catalyzed radical carbooxygenation: alkylation and alkoxylation of styrenes.

PubMed

Liao, Zhixiong; Yi, Hong; Li, Zheng; Fan, Chao; Zhang, Xu; Liu, Jie; Deng, Zixin; Lei, Aiwen

2015-01-01

A simple copper-catalyzed direct radical carbooxygenation of styrenes is developed utilizing alkyl bromides as radical resources. This catalytic radical difunctionalization accomplishes both alkylation and alkoxylation of styrenes in one pot. A broad range of styrenes and alcohols are well tolerated in this transformation. The EPR experiment shows that alkyl halides could oxidize Cu(I) to Cu(II) in this transformation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Detection of OH on photolysis of styrene oxide at 193 nm in gas phase

NASA Astrophysics Data System (ADS)

Kumar, Awadhesh; SenGupta, Sumana; Pushpa, K. K.; Naik, P. D.; Bajaj, P. N.

2006-10-01

Photodissociation of styrene oxide at 193 nm in gas phase generates OH, as detected by laser-induced fluorescence technique. Under similar conditions, OH was not observed from ethylene and propylene oxides, primarily because of their low absorption cross-sections at 193 nm. Mechanism of OH formation involves first opening of the three-membered ring from the ground electronic state via cleavage of either of two C sbnd O bonds, followed by isomerization to enolic forms of phenylacetaldehyde and acetophenone, and finally scission of the C sbnd OH bond of enols. Ab initio molecular orbital calculations support the proposed mechanism.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-02

... workers of the subject firm. The workers are engaged in the production of styrene monomer and polystyrene... increased customer imports of styrene monomer and polystyrene pellets. The amended notice applicable to TA-W...

Oxidative stress due to (R)-styrene oxide exposure and the role of antioxidants in non-Swiss albino (NSA) mice.

PubMed

Meszka-Jordan, Anna; Mahlapuu, Riina; Soomets, Ursel; Carlson, Gary P

2009-01-01

Styrene produces lung and liver damage that may be related to oxidative stress. The purpose of this study was to investigate the toxicity of (R)-styrene oxide (R-SO), the more active enantiomeric metabolite of styrene, and the protective properties of the antioxidants glutathione (GSH), N-acetylcysteine (NAC), and 4-methoxy-L-tyrosinyl-gamma-L-glutamyl-L-cysteinyl-glycine (UPF1) against R-SO-induced toxicity in non-Swiss Albino (NSA) mice. UPF1 is a synthetic GSH analog that was shown to have 60 times the ability to scavenge reactive oxygen species (ROS) in comparison to GSH. R-SO toxicity to the lung was measured by elevations in the activity of lactate dehydrogenase (LDH), protein concentration, and number of cells in bronchoalveolar lavage fluid (BALF). Toxicity to the liver was measured by increases in serum sorbitol dehydrogenase (SDH) activity. Antioxidants were not able to decrease the adverse effects of R-SO on lung. However, NAC (200 mg/kg) ip and GSH (600 mg/kg), administered orally prior to R-SO (300 mg/kg) ip, showed significant protection against liver toxicity as measured by SDH activity. Unexpectedly, a synthetic GSH analog, UPF1 (0.8 mg/kg), administered intravenously (iv) prior to R-SO, produced a synergistic effect with regard to liver and lung toxicity. Treatment with UPF1 (0.8 mg/kg) iv every other day for 1 wk for preconditioning prior to R-SO ip did not result in any protection against liver and lung toxicity, but rather enhanced the toxicity when administered prior R-SO. The results of the present study demonstrated protection against R-SO toxicity in liver but not lung by the administration of the antioxidants NAC and GSH.

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

PubMed

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 (<85 dBA p = 0.0001; ≥85 dB(A) p = 0.0192) interacted significantly with styrene exposure. Occupational exposure to styrene is a risk factor for hearing loss, and styrene-exposed workers should be included in hearing loss prevention programs.

Epoxidation of the methamphetamine pyrolysis product, trans-phenylpropene, to trans-phenylpropylene oxide by CYP enzymes and stereoselective glutathione adduct formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanga, Madhu; Younis, Islam R.; Tirumalai, Padma S.

2006-03-01

Pyrolytic products of smoked methamphetamine hydrochloride are well established. Among the various degradation products formed, trans-phenylpropene (trans-{beta}-methylstyrene) is structurally similar to styrene analogues known to be bioactivated by CYP enzymes. In human liver microsomes, trans-phenylpropene was converted to the epoxide trans-phenylpropylene oxide (trans-2-methyl-3-phenyloxirane) and cinnamyl alcohol. Incubation of trans-phenylpropene with microsomes in the presence of enzyme-specific P450 enzyme inhibitors indicated the involvement of CYP2E1, CYP1A2, and CYP3A4 enzymes. Both (R,R)-phenylpropylene oxide and (S,S)-phenylpropylene oxide were formed in human liver microsomal preparations. Enantiomers of trans-phenylpropylene oxide were stereoselectively and regioselectively conjugated in a Phase II drug metabolism reaction catalyzed by humanmore » liver cytosolic enzymes consisting of conjugation with glutathione. The structure of the phenylpropylene oxide-glutathione adduct is consistent with nucleophilic ring-opening by attack at the benzylic carbon. Exposure of cultured C6 glial cells to (S,S)-phenylpropylene oxide produced a cytotoxic response in a concentration-dependent manner based on cell degeneration and death.« less

Adsorption of ethoxylated styrene oxide and polyacrylic acid and mixtures there of on organic pigment.

PubMed

Wijting, W K; Laven, J; van Benthem, R A T M; de With, G

2008-11-01

The adsorption of two polymeric surfactants on an organic pigment was investigated. As surfactants the anionic polyacrylic acid sodium salt (PANa, M(W)=15,000) and a non-ionic block copolymer surfactant based on styrene oxide (SO) and ethylene oxide (EO) (M(W)=1500) were used. The adsorption behavior was analyzed by size exclusion chromatography of the supernatant after centrifugation of the pigment dispersions. It was found that PANa has no affinity to the pigment, whereas SO-EO has a strong affinity to the pigment surface. Competitive adsorption of PANa and SO-EO was not observed. Addition of SO-EO yields stable dispersions.

Solubilization of docetaxel in poly(ethylene oxide)-block-poly(butylene/styrene oxide) micelles.

PubMed

Elsabahy, Mahmoud; Perron, Marie-Eve; Bertrand, Nicolas; Yu, Ga-Er; Leroux, Jean-Christophe

2007-07-01

Poly(ethylene oxide)-block-poly(styrene oxide) (PEO-b-PSO) and PEO-b-poly(butylene oxide) (PEO-b-PBO) of different chain lengths were synthesized and characterized for their self-assembling properties in water by dynamic/static light scattering, spectrofluorimetry, and transmission electron microscopy. The resulting polymeric micelles were evaluated for their ability to solubilize and protect the anticancer drug docetaxel (DCTX) from degradation. The drug release kinetics as well as the cytotoxicity of the loaded micelles were assessed in vitro. All polymers formed micelles with a highly viscous core at low critical association concentrations (<10 mg/L). Micelle morphology depended on the nature of the hydrophobic block, with PBO- and PSO-based micelles yielding monodisperse spherical and cylindrical nanosized aggregates, respectively. The maximum solubilization capacity for DCTX ranged from 0.7 to 4.2% and was the highest for PSO micelles exhibiting the longest hydrophobic segment. Despite their high affinity for DCTX, PEO-b-PSO micelles were not able to efficiently protect DCTX against hydrolysis under accelerated stability testing conditions. Only PEO-b-PBO bearing 24 BO units afforded significant protection against degradation. In vitro, DCTX was released slower from the latter micelles, but all formulations possessed a similar cytotoxic effect against PC-3 prostate cancer cells. These data suggest that PEO-b-P(SO/BO) micelles could be used as alternatives to conventional surfactants for the solubilization of taxanes.

Comparing in situ removal strategies for improving styrene bioproduction.

PubMed

McKenna, Rebekah; Moya, Luis; McDaniel, Matthew; Nielsen, David R

2015-01-01

As an important conventional monomer compound, the biological production of styrene carries significant promise with respect to creating novel sustainable materials. Since end-product toxicity presently limits styrene production by previously engineered Escherichia coli, in situ product removal by both solvent extraction and gas stripping were explored as process-based strategies for circumventing its inhibitory effects. In solvent extraction, the addition of bis(2-ethylhexyl)phthalate offered the greatest productivity enhancement, allowing net volumetric production of 836 ± 64 mg/L to be reached, representing a 320 % improvement over single-phase cultures. Gas stripping rates, meanwhile, were controlled by rates of bioreactor agitation and, to a greater extent, aeration. A periodic gas stripping protocol ultimately enabled up to 561 ± 15 mg/L styrene to be attained. Lastly, by relieving the effects of styrene toxicity, new insight was gained regarding subsequent factors limiting its biosynthesis in E. coli and strategies for future strain improvement are discussed.

Company-level, semi-quantitative assessment of occupational styrene exposure when individual data are not available.

PubMed

Kolstad, Henrik A; Sønderskov, Jette; Burstyn, Igor

2005-03-01

In epidemiological research, self-reported information about determinants and levels of occupational exposures is difficult to obtain, especially if the disease under study has a high mortality rate or follow-up has exceeded several years. In this paper, we present a semi-quantitative exposure assessment strategy for nested case-control studies of styrene exposure among workers of the Danish reinforced plastics industry when no information on job title, task or other indicators of individual exposure were readily available from cases and controls. The strategy takes advantage of the variability in styrene exposure level and styrene exposure probability across companies. The study comprised 1522 cases of selected malignancies and neurodegenerative diseases and controls employed in 230 reinforced plastics companies and other related industries. Between 1960 and 1996, 3057 measurements of styrene exposure level obtained from 191 companies, were identified. Mixed effects models were used to estimate expected styrene exposure levels by production characteristics for all companies. Styrene exposure probability within each company was estimated for all but three cases and controls from the fraction of laminators, which was reported by a sample of 945 living colleagues of the cases and controls and by employers and dealers of plastic raw materials. The estimates were validated from a subset of 427 living cases and controls that reported their own work as laminators in the industry. We computed styrene exposure scores that integrated estimated styrene exposure level and styrene exposure probability. Product (boats), process (hand and spray lamination) and calendar year period were the major determinants of styrene exposure level. Within-company styrene exposure variability increased by calendar year and was accounted for when computing the styrene exposure scores. Exposure probability estimates based on colleagues' reports showed the highest predictive values in the

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

PubMed

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.

The Iodochlorination of Styrene: An Experiment that Makes a Difference

ERIC Educational Resources Information Center

Amiet, R. Gary; Urban, Sylvia

2008-01-01

The iodochlorination of styrene, involving the addition of iodine monochloride to styrene, followed by the sodium methoxide-initiated dehydrohalogenation of the product results in a variable mixture of substituted styrenes by way of various substitution and elimination reaction mechanisms. As a result individual results are obtained for each…

Synchrotron-based FTIR microspectroscopy for the mapping of photo-oxidation and additives in acrylonitrile-butadiene-styrene model samples and historical objects.

PubMed

Saviello, Daniela; Pouyet, Emeline; Toniolo, Lucia; Cotte, Marine; Nevin, Austin

2014-09-16

Synchrotron-based Fourier transform infrared micro-spectroscopy (SR-μFTIR) was used to map photo-oxidative degradation of acrylonitrile-butadiene-styrene (ABS) and to investigate the presence and the migration of additives in historical samples from important Italian design objects. High resolution (3×3 μm(2)) molecular maps were obtained by FTIR microspectroscopy in transmission mode, using a new method for the preparation of polymer thin sections. The depth of photo-oxidation in samples was evaluated and accompanied by the formation of ketones, aldehydes, esters, and unsaturated carbonyl compounds. This study demonstrates selective surface oxidation and a probable passivation of material against further degradation. In polymer fragments from design objects made of ABS from the 1960s, UV-stabilizers were detected and mapped, and microscopic inclusions of proteinaceous material were identified and mapped for the first time. Copyright © 2014 Elsevier B.V. All rights reserved.

Occupational styrene exposure for twelve product categories in the reinforced-plastics industry.

PubMed

Lemasters, G K; Carson, A; Samuels, S J

1985-08-01

Approximately 1500 occupational styrene exposure values from 28 reinforced-plastic manufacturers were collected retrospectively from companies and state and federal agencies. This report describes the major types of manufacturing processes within the reinforced-plastics industry and reports on the availability, collection and analysis of historical exposure information. Average exposure to styrene in most open-mold companies (24-82 ppm) was generally 2-3 times the exposure in press-mold companies (11-26 ppm). Manufacturers of smaller boats had mean styrene exposures of 82 ppm as compared to 37 ppm for yacht companies. There was considerable overlap in styrene exposure among job titles classified as directly exposed within open- and press-mold processing.

Synthesis of a highly dispersed CuO catalyst on CoAl-HT for the epoxidation of styrene.

PubMed

Hu, Rui; Yang, Pengfei; Pan, Yongning; Li, Yunpeng; He, Yufei; Feng, Junting; Li, Dianqing

2017-10-10

A highly dispersed CuO catalyst was prepared by the deposition-precipitation method and evaluated for the catalytic epoxidation of styrene with tert-butyl hydroperoxide (TBHP) as the oxidant under solvent acetonitrile conditions. Compared with MgAl hydrotalcite (MgAl-HT)-, MgO-, TiO 2 -, C-, and MCM-22-supported catalysts, CuO/CoAl-HT exhibited preferable activity and selectivity towards styrene oxide (72% selectivity at 99.5% styrene conversion) due to its high dispersion of CuO and surface area of Cu. The improved dispersion of CuO/CoAl-HT could be ascribed to the nature of HT support, especially the synergistic effect of acidic and basic sites on the surface, which facilitated the formation of highly dispersed CuO species. A structure-performance relationship study indicated that copper(ii) in CuO was the active site for the epoxidation and oxidation of styrene, and that Cu II of rich electronic density favored the improvement of selectivity of styrene oxide. Based on these results, a reaction mechanism was proposed. Moreover, the preferred catalytic performance of CuO/CoAl-HT could be maintained in five reused cycles.

Effect of styrene exposure on plasma parameters, molecular mechanisms and gene expression in rat model islet cells.

PubMed

Niaz, Kamal; Hassan, Fatima Ismail; Mabqool, Faheem; Khan, Fazlullah; Momtaz, Saeideh; Baeeri, Maryam; Navaei-Nigjeh, Mona; Rahimifard, Mahban; Abdollahi, Mohammad

2017-09-01

Styrene is an aromatic hydrocarbon compound present in the environment and have primary exposure through plastic industry. The current study was designed to evaluate styrene-induced toxicity parameters in rat plasma fasting blood glucose (FBG) level, oral glucose tolerance, insulin secretion, oxidative stress, and inflammatory cytokines in cellular and molecular levels. Styrene was dissolved in corn oil and administered at different doses (250, 500, 1000, 1500, 2000mg/kg/day and control) to each rat, for 42days. In treated groups, styrene significantly increased fasting blood glucose, plasma insulin (p<0.001) and glucose tolerance. Glucose tolerance, insulin resistance and hyperglycemia were found to be the main consequences correlating gene expression of islet cells. Styrene caused a significant enhancement of oxidative stress markers (p<0.001) and inflammatory cytokines in a dose and concentration-dependent manner in plasma (p<0.001). Moreover, the activities of caspase-3 and -9 of the islet cells were significantly up-regulated by this compound at 1500 and 2000mg/kg/day styrene administrated groups (p<0.001). The relative fold change of GLUD1 was downregulated (p<0.05) and upregulated at 1500 and 2000mg/kg, respectively (p<0.01). The relative fold changes of GLUT2 were down regulated at 250 and 1000mg/kg and up regulated in 500, 1500 and 2000mg/kg doses of styrene (p<0.01). The expression level of GCK indicated a significant upregulation at 250mg/kg and downregulation of relative fold changes in the remaining doses of styrene, except for no change at 2000mg/kg of styrene for GCK. Targeting genes (GLUD1, GLUT2 and GCK) of the pancreatic islet cells in styrene exposed groups, disrupted gluconeogenesis, glycogenolysis pathways and insulin secretory functions. The present study illustrated that fasting blood glucose, insulin pathway, oxidative balance, inflammatory cytokines, cell viability and responsible genes of glucose metabolism are susceptible to styrene

Proton exchange membranes prepared by grafting of styrene/divinylbenzene into crosslinked PTFE membranes

NASA Astrophysics Data System (ADS)

Li, Jingye; Ichizuri, Shogo; Asano, Saneto; Mutou, Fumihiro; Ikeda, Shigetoshi; Iida, Minoru; Miura, Takaharu; Oshima, Akihiro; Tabata, Yoneho; Washio, Masakazu

2005-07-01

Thin PTFE membranes were prepared by coating the PTFE dispersion onto the aluminum films. Thus the thin crosslinked PTFE (RX-PTFE) membranes were obtained by means of electron beam irradiation above the melting temperature of PTFE under oxygen-free atmosphere. The RX-PTFE membranes were pre-irradiated and grafted by styrene with or without divinylbenzene (DVB) in liquid phase. The existence of DVB accelerated the initial grafting rate. The styrene grafted RX-PTFE membranes are white colored, on the other hand, the styrene/DVB grafted RX-PTFE membranes are colorless. The proton exchange membranes (PEMs) were obtained by sulfonating the grafted membranes using chlorosulfonic acid. The ion exchange capacity (IEC) values of the PEMs ranging from 1.5 to 2.8 meq/g were obtained. The PEMs made from the styrene/DVB grafted membranes showed higher chemical stability than those of the styrene grafted membranes under oxidative circumstance.

Based on an analysis of mode of action, styrene-induced mouse lung tumors are not a human cancer concern.

PubMed

Cruzan, George; Bus, James S; Andersen, Melvin E; Carlson, Gary P; Banton, Marcy I; Sarang, Satinder S; Waites, Robbie

2018-06-01

Based on 13 chronic studies, styrene exposure causes lung tumors in mice, but no tumor increases in other organs in mice or rats. Extensive research into the mode of action demonstrates the key events and human relevance. Key events are: metabolism of styrene by CYP2F2 in mouse lung club cells to ring-oxidized metabolites; changes in gene expression for metabolism of lipids and lipoproteins, cell cycle and mitotic M-M/G1 phases; cytotoxicity and mitogenesis in club cells; and progression to preneoplastic/neoplastic lesions in lung. Although styrene-7,8-oxide (SO) is a common genotoxic styrene metabolite in in vitro studies, the data clearly demonstrate that SO is not the proximate toxicant and that styrene does not induce a genotoxic mode of action. Based on complete attenuation of styrene short-term and chronic toxicity in CYP2F2 knockout mice and similar attenuation in CYP2F1 (humanized) transgenic mice, limited metabolism of styrene in human lung by CYP2F1, 2 + orders of magnitude lower SO levels in human lung compared to mouse lung, and lack of styrene-related increase in lung cancer in humans, styrene does not present a risk of cancer to humans. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Enhancing mechanical and thermal properties of styrene-butadiene rubber/carboxylated acrylonitrile butadiene rubber blend by the usage of graphene oxide with diverse oxidation degrees

NASA Astrophysics Data System (ADS)

Xue, Xiaodong; Yin, Qing; Jia, Hongbing; Zhang, Xuming; Wen, Yanwei; Ji, Qingmin; Xu, Zhaodong

2017-11-01

Graphene oxide (GO) with various oxidation degrees were prepared through a modified Hummer's method by varying the dosage of oxidizing agent. Styrene-butadiene rubber (SBR)/carboxylated acrylonitrile butadiene rubber (XNBR)/GO nanocomposites were fabricated by aqueous-phase mixing of GO colloidal dispersion with SBR latex and a small loading of XNBR latex, followed by co-coagulation. Effects of GO oxidation degree on the morphology, structure, mechanical and thermal properties of nanocomposites were thoroughly investigated. The results showed that the mechanical strength of nanocomposites were enhanced with the increase of oxidation degree of GO. Especially, when the weight ratio of KMnO4 to graphite was 15/5, the tensile strength, tear strength and thermal conductivity of SBR/XNBR/GO filled with 3 phr (parts per hundred rubber) GO increased by 255.3%, 141.5% and 22.8%, respectively, compared to those of neat SBR/XNBR blend. In addition, the thermal stability and the solvent resistance of the nanocomposites were also improved significantly. This work suggested that GO with higher oxidation degree could effectively improve the properties of SBR/XNBR blend.

Ambient ultrafine particles reduce endothelial nitric oxide production via S-glutathionylation of eNOS.

PubMed

Du, Yunfeng; Navab, Mohamad; Shen, Melody; Hill, James; Pakbin, Payam; Sioutas, Constantinos; Hsiai, Tzung K; Li, Rongsong

2013-07-05

Exposure to airborne particulate pollutants is intimately linked to vascular oxidative stress and inflammatory responses with clinical relevance to atherosclerosis. Particulate matter (PM) has been reported to induce endothelial dysfunction and atherosclerosis. Here, we tested whether ambient ultrafine particles (UFP, diameter <200 nm) modulate eNOS activity in terms of nitric oxide (NO) production via protein S-glutathionylation. Treatment of human aortic endothelial cells (HAEC) with UFP significantly reduced NO production. UFP-mediated reduction in NO production was restored in the presence of JNK inhibitor (SP600125), NADPH oxidase inhibitor (Apocynin), anti-oxidant (N-acetyl cysteine), and superoxide dismutase mimetics (Tempol and MnTMPyP). UFP exposure increased the GSSG/GSH ratio and eNOS S-glutathionylation, whereas over-expression of Glutaredoxin-1 (to inhibit S-glutathionylation) restored UFP-mediated reduction in NO production by nearly 80%. Thus, our findings suggest that eNOS S-glutathionylation is a potential mechanism underlying ambient UFP-induced reduction of NO production. Copyright © 2013 Elsevier Inc. All rights reserved.

Ambient ultrafine particles reduce endothelial nitric oxide production via S-glutathionylation of eNOS

PubMed Central

Du, Yunfeng; Navab, Mohamad; Shen, Melody; Hill, James; Pakbin, Payam; Sioutas, Constantinos; Hsiai, Tzung; Li, Rongsong

2013-01-01

Exposure to airborne particulate pollutants is intimately linked to vascular oxidative stress and inflammatory responses with clinical relevance to atherosclerosis. Particulate matter (PM) has been reported to induce endothelial dysfunction and atherosclerosis. Here, we tested whether ambient ultrafine particles (UFP, diameter < 200 nm) modulate eNOS activity in terms of nitric oxide (NO) production via protein S-glutathionylation. Treatment of human aortic endothelial cells (HAEC) with UFP significantly reduced NO production. UFP-mediated reduction in NO production was restored in the presence of JNK inhibitor (SP600125), NADPH oxidase inhibitor (Apocynin), anti-oxidant (N-acetyl cysteine), and superoxide dismutase mimetics (Tempol and MnTMPyP). UFP exposure increased the GSSG/GSH ratio and eNOS S-glutathionylation, whereas over-expression of Glutaredoxin-1 (to inhibit S-glutathionylation) restored UFP-mediated reduction in NO production by nearly 80%. Thus, our findings suggest that eNOS S-glutathionylation is a potential mechanism underlying ambient UFP-induced reduction of NO production. PMID:23751346

Preparation, characterization and conductivity study of nitro-mercurated styrene butadiene rubber/silver doped zinc oxide nanocomposites

NASA Astrophysics Data System (ADS)

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.

Polydispersity effects in poly(isoprene-b-styrene-b-ethylene oxide) triblock terpolymers

NASA Astrophysics Data System (ADS)

Meuler, Adam J.; Ellison, Christopher J.; Qin, Jian; Evans, Christopher M.; Hillmyer, Marc A.; Bates, Frank S.

2009-06-01

Four hydroxyl-terminated poly(isoprene-b-styrene) diblock copolymers with comparable molecular weights and compositions (equivalent volume fractions of polyisoprene and polystyrene) but different polystyrene block polydispersity indices (Mw/Mn=1.06,1.16,1.31,1.44) were synthesized by anionic polymerization using either sec-butyllithium or the functional organolithium 3-triisopropylsilyloxy-1-propyllithium. Poly(ethylene oxide) (PEO) blocks were grown from the end of each of these parent diblocks to yield four series of poly(isoprene-b-styrene-b-ethylene oxide) (ISO) triblock terpolymers that were used to interrogate the effects of varying the polydispersity of the middle bridged polystyrene block. In addition to the neat triblock samples, 13 multicomponent blends were prepared at four different compositions from the ISO materials containing a polystyrene segment with Mw/Mn=1.06; these blends were used to probe the effects of increasing the polydispersity of the terminal PEO block. The melt-phase behavior of all samples was characterized using small-angle X-ray scattering and dynamic mechanical spectroscopy. Numerous polydispersity-driven morphological transitions are reported, including transitions from lamellae to core-shell gyroid, from core-shell gyroid to hexagonally packed cylinders, and from network morphologies [either O70 (the orthorhombic Fddd network) or core-shell gyroid] to lamellae. Domain periodicities and order-disorder transition temperatures also vary with block polydispersities. Self-consistent field theory calculations were performed to supplement the experimental investigations and help elucidate the molecular factors underlying the polydispersity effects. The consequences of varying the polydispersity of the terminal PEO block are comparable to the polydispersity effects previously reported in AB diblock copolymers. Namely, domain periodicities increase with increasing polydispersity and domain interfaces tend to curve toward polydisperse

The microwave-assisted ionic liquid nanocomposite synthesis: platinum nanoparticles on graphene and the application on hydrogenation of styrene

PubMed Central

2013-01-01

The microwave-assisted nanocomposite synthesis of metal nanoparticles on graphene or graphite oxide was introduced in this research. With microwave assistance, the Pt nanoparticles on graphene/graphite oxide were successfully produced in the ionic liquid of 2-hydroxyethanaminium formate [HOCH2CH2NH3][HCO2]. On graphene/graphite oxide, the sizes of Pt nanoparticles were about 5 to 30 nm from transmitted electron microscopy (TEM) results. The crystalline Pt structures were examined by X-ray diffraction (XRD). Since hydrogenation of styrene is one of the important well-known chemical reactions, herein, we demonstrated then the catalytic hydrogenation capability of the Pt nanoparticles on graphene/graphite oxide for the nanocomposite to compare with that of the commercial catalysts (Pt/C and Pd/C, 10 wt.% metal catalysts on activated carbon from Strem chemicals, Inc.). The conversions with the Pt nanoparticles on graphene are >99% from styrene to ethyl benzene at 100°C and under 140 psi H2 atmosphere. However, ethyl cyclohexane could be found as a side product at 100°C and under 1,520 psi H2 atmosphere utilizing the same nanocomposite catalyst. PMID:24103100

Investigating bacterial populations in styrene-degrading biofilters by 16S rDNA tag pyrosequencing.

PubMed

Portune, Kevin J; Pérez, M Carmen; Álvarez-Hornos, F Javier; Gabaldón, Carmen

2015-01-01

Microbial biofilms are essential components in the elimination of pollutants within biofilters, yet still little is known regarding the complex relationships between microbial community structure and biodegradation function within these engineered ecosystems. To further explore this relationship, 16S rDNA tag pyrosequencing was applied to samples taken at four time points from a styrene-degrading biofilter undergoing variable operating conditions. Changes in microbial structure were observed between different stages of biofilter operation, and the level of styrene concentration was revealed to be a critical factor affecting these changes. Bacterial genera Azoarcus and Pseudomonas were among the dominant classified genera in the biofilter. Canonical correspondence analysis (CCA) and correlation analysis revealed that the genera Brevundimonas, Hydrogenophaga, and Achromobacter may play important roles in styrene degradation under increasing styrene concentrations. No significant correlations (P > 0.05) could be detected between biofilter operational/functional parameters and biodiversity measurements, although biological heterogeneity within biofilms and/or technical variability within pyrosequencing may have considerably affected these results. Percentages of selected bacterial taxonomic groups detected by fluorescence in situ hybridization (FISH) were compared to results from pyrosequencing in order to assess the effectiveness and limitations of each method for identifying each microbial taxon. Comparison of results revealed discrepancies between the two methods in the detected percentages of numerous taxonomic groups. Biases and technical limitations of both FISH and pyrosequencing, such as the binding of FISH probes to non-target microbial groups and lack of classification of sequences for defined taxonomic groups from pyrosequencing, may partially explain some differences between the two methods.

Ototoxic effects of occupational exposure to styrene and co-exposure to styrene and noise.

PubMed

Sliwińska-Kowalska, Mariola; Zamyslowska-Szmytke, Ewa; Szymczak, Wieslaw; Kotylo, Piotr; Fiszer, Marta; Wesolowski, Wiktor; Pawlaczyk-Luszczynska, Malgorzata

2003-01-01

Ototoxicity of styrene and the synergistic action of styrene and noise have been shown in rats. The respective data in humans are scarce and equivocal. This study evaluated the effects of occupational exposure to styrene and combined exposures to styrene and noise on hearing. The study group, comprised of 290-yacht yard and plastic factory workers, was exposed to a mixture of organic solvents, having styrene as its main compound. The reference group, totaling 223 subjects, included (1) white-collar workers, exposed neither to solvents nor noise and (2) metal factory workers, exposed exclusively to noise. All subjects were assessed by means of a detailed questionnaire and underwent otorhinolaryngological and audiometric examinations. Multiple logistic regression analysis revealed almost a 4-fold (or 3.9; 95% CI = 2.4-6.2) increase in the odds of developing hearing loss related to styrene exposure. The factors adjusted for were: age, gender, current occupational exposure to noise, and exposure to noise in the past. In cases of the combined exposures to styrene and noise, the odds ratios were two to three times higher than the respective values for styrene-only and noise-only exposed subjects. The mean hearing thresholds--adjusted for age, gender, and exposure to noise--were significantly higher in the solvent-exposed group than in the unexposed reference group at all frequencies tested. A positive linear relationship existed between an averaged working life exposure to styrene concentration and a hearing threshold at the frequencies of 6 and 8 kHz. This study provides the epidemiological evidence that occupational exposure to styrene is related to an increased risk of hearing loss. Combined exposures to noise and styrene seem to be more ototoxic than exposure to noise alone.

Letter to the Editor: Styrene-producing microbes in food-stuff

USDA-ARS?s Scientific Manuscript database

An article was published in Journal of Food Science, August 2009 (Vol. 74, Nr 6) entitled “Natural formation of styrene by cinnamon mold flora”. In the article, the authors reported on the production of styrene from several fungi typically found on cinnamon, and used cinnamic acid and similar analog...

Compound oxidized styrylphosphine. [flame resistant vinyl polymers

NASA Technical Reports Server (NTRS)

Paciorek, K. J. L. (Inventor)

1979-01-01

A process is described for preparing flame resistant, nontoxic vinyl polymers which contain phosphazene groups and which do not emit any toxic or corrosive products when they are oxidatively degraded. Homopolymers, copolymers, and terpolymers of a styrene based monomer are prepared by polymerizing at least one oxidized styrylphosphine monomer from a group of organic azides, or by polymerizing p-diphenylphosphinestyrene and then oxidizing that monomer with an organoazide from the group of (C6H5)2P(O)N3, (C6H5O)2P(O)N3, (C6H5)2C3N3(N3), and C6H5C3N3(N3)2. Copolymers can also be prepared by copolymerizing styrene with at least one oxidized styrylphosphine monomer.

Free volume dependence on electrical properties of Poly (styrene co-acrylonitrile)/Nickel oxide polymer nanocomposites

NASA Astrophysics Data System (ADS)

Ningaraju, S.; Hegde, Vinayakaprasanna N.; Prakash, A. P. Gnana; Ravikumar, H. B.

2018-04-01

Polymer nanocomposites of Poly (styrene co-acrylonitrile)/Nickel Oxide (PSAN/NiO) have been prepared. The increased free volume sizes up to 0.4 wt% of NiO loading indicates overall reduction in packing density of polymer network. The decreased o-Ps lifetime (τ3) at higher concentration of NiO indicates improved interfacial interaction between the surface of NiO nanoparticles and side chain of PSAN polymer matrix. The increased AC/DC conductivity at lower wt% of NiO loading demonstrates increased number of electric charge carriers/mobile ions and their mobility. The increased dielectric constant and dielectric loss up to 0.4 wt% of NiO loading suggests the increased dipoles polarization.

High-performance free-standing capacitor electrodes of multilayered Co9S8 plates wrapped by carbonized poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/reduced graphene oxide

NASA Astrophysics Data System (ADS)

Yao, Tinghui; Li, Yali; Liu, Dequan; Gu, Yipeng; Qin, Shengchun; Guo, Xin; Guo, Hui; Ding, Yongqiang; Liu, Qiming; Chen, Qiang; Li, Junshuai; He, Deyan

2018-03-01

In this paper, a free-standing electrode structure composed of multilayered Co9S8 plates wrapped by carbonized poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/reduced graphene oxide (PEDOT:PSS/rGO) layers is introduced. Excellent supercapacitive behaviors, especially long cycling stability at high current densities are delivered owing to the synergetic effects of stable electrical contact between the active material and carbonized PEDOT:PSS/rGO due to the wrapped configuration, efficient charge exchange between the multilayered Co9S8 plates and electrolyte, improved electrical conductance by rGO, and plenty of voids for accommodating volume changes. For the optimized electrode (starting materials: 0.5 mL PEDOT:PSS, 1.0 mL GO (6.0 mg mL-1) and 10.0 mg Co(OH)2), a specific capacitance of about 788.9 F g-1 at 1.0 A g-1 and good cycling stability of over 100% of the initial capacitance (∼488.6 F g-1) after 10000 cycles at a current density of 15.0 A g-1 can be achieved. The assembled asymmetric supercapacitor based on the optimized electrode//active carbon exhibits an energy density of ∼19.6 Wh kg-1 at a power density of 400.9 W kg-1.

Fabrication of Acrylonitrile-Butadiene-Styrene Nanostructures with Anodic Alumina Oxide Templates, Characterization and Biofilm Development Test for Staphylococcus epidermidis

PubMed Central

Desrousseaux, Camille; Cueff, Régis; Aumeran, Claire; Garrait, Ghislain; Mailhot-Jensen, Bénédicte; Traoré, Ousmane; Sautou, Valérie

2015-01-01

Medical devices can be contaminated by microbial biofilm which causes nosocomial infections. One of the strategies for the prevention of such microbial adhesion is to modify the biomaterials by creating micro or nanofeatures on their surface. This study aimed (1) to nanostructure acrylonitrile-butadiene-styrene (ABS), a polymer composing connectors in perfusion devices, using Anodic Alumina Oxide templates, and to control the reproducibility of this process; (2) to characterize the physico-chemical properties of the nanostructured surfaces such as wettability using captive-bubble contact angle measurement technique; (3) to test the impact of nanostructures on Staphylococcus epidermidis biofilm development. Fabrication of Anodic Alumina Oxide molds was realized by double anodization in oxalic acid. This process was reproducible. The obtained molds present hexagonally arranged 50 nm diameter pores, with a 100 nm interpore distance and a length of 100 nm. Acrylonitrile-butadiene-styrene nanostructures were successfully prepared using a polymer solution and two melt wetting methods. For all methods, the nanopicots were obtained but inside each sample their length was different. One method was selected essentially for industrial purposes and for better reproducibility results. The flat ABS surface presents a slightly hydrophilic character, which remains roughly unchanged after nanostructuration, the increasing apparent wettability observed in that case being explained by roughness effects. Also, the nanostructuration of the polymer surface does not induce any significant effect on Staphylococcus epidermidis adhesion. PMID:26284922

Bacterial degradation of styrene in waste gases using a peat filter.

PubMed

Arnold, M; Reittu, A; von Wright, A; Martikainen, P J; Suihko, M L

1997-12-01

A biofiltration process was developed for styrene-containing off-gases using peat as filter material. The average styrene reduction ratio after 190 days of operation was 70% (max. 98%) and the mean styrene elimination capacity was 12 g m-3 h-1 (max. 30 g m-3 h-1). Efficient styrene degradation required addition of nutrients to the peat, adjustment of the pH to a neutral level and efficient control of the humidity. Maintenance of the water balance was easier in a down-flow than in an up-flow process, the former consequently resulting in much better filtration efficiency. The optimum operation temperature was around 23 degrees C, but the styrene removal was still satisfactory at 12 degrees C. Seven different bacterial isolates belonging to the genera Tsukamurella, Pseudomonas, Sphingomonas, Xanthomonas and an unidentified genus in the gamma group of the Proteobacteria isolated from the microflora of active peat filter material were capable of styrene degradation. The isolates differed in their capacity to decompose styrene to carbon dioxide and assimilate it to biomass. No toxic intermediate degradation products of styrene were detected in the filter outlet gas or in growing cultures of isolated bacteria. The use of these isolates in industrial biofilters is beneficial at low styrene concentrations and is safe from both the environmental and public health points of view.

Synthesis and photooxidation of styrene copolymer bearing camphorquinone pendant groups

PubMed Central

Moszner, Norbert; Lukáč, Ivan

2012-01-01

Summary (±)-10-Methacryloyloxycamphorquinone (MCQ) was synthesized from (±)-10-camphorsulfonic acid either by a known seven-step synthetic route or by a novel, shorter five-step synthetic route. MCQ was copolymerized with styrene (S) and the photochemical behavior of the copolymer MCQ/S was compared with that of a formerly studied copolymer of styrene with monomers containing the benzil (BZ) moiety (another 1,2-dicarbonyl). Irradiation (λ > 380 nm) of aerated films of styrene copolymers with monomers containing the BZ moiety leads to the insertion of two oxygen atoms between the carbonyl groups of BZ and to the formation of benzoyl peroxide (BP) as pendant groups on the polymer backbone. An equivalent irradiation of MCQ/S led mainly to the insertion of only one oxygen atom between the carbonyl groups of camphorquinone (CQ) and to the formation of camphoric anhydride (11) covalently bound to the polymer backbone. While the decomposition of pendant BP groups formed in irradiated films of styrene copolymers with pendant BZ groups leads to crosslinking, only small molecular-weight changes in irradiated MCQ/S were observed. PMID:22509202

Styrene-spaced copolymers including anthraquinone and β-O-4 lignin model units: synthesis, characterization and reactivity under alkaline pulping conditions.

PubMed

Megiatto, Jackson D; Cazeils, Emmanuel; Ham-Pichavant, Frédérique; Grelier, Stéphane; Gardrat, Christian; Castellan, Alain

2012-05-14

A series of random copoly(styrene)s has been synthesized via radical polymerization of functionalized anthraquinone (AQ) and β-O-4 lignin model monomers. The copolymers were designed to have a different number of styrene spacer groups between the AQ and β-O-4 lignin side chains aiming at investigating the distance effects on AQ/β-O-4 electron transfer mechanisms. A detailed molecular characterization, including techniques such as size exclusion chromatography, MALDI-TOF mass spectrometry, and (1)H, (13)C, (31)P NMR and UV-vis spectroscopies, afforded quantitative information about the composition of the copolymers as well as the average distribution of the AQ and β-O-4 groups in the macromolecular structures. TGA and DSC thermal analysis have indicated that the copolymers were thermally stable under regular pulping conditions, revealing the inertness of the styrene polymer backbone in the investigation of electron transfer mechanisms. Alkaline pulping experiments showed that close contact between the redox active side chains in the copolymers was fundamental for an efficient degradation of the β-O-4 lignin model units, highlighting the importance of electron transfer reactions in the lignin degradation mechanisms catalyzed by AQ. In the absence of glucose, AQ units oxidized phenolic β-O-4 lignin model parts, mainly by electron transfer leading to vanillin as major product. By contrast, in presence of glucose, anthrahydroquinone units (formed by reduction of AQ) reduced the quinone-methide units (issued by dehydration of phenolic β-O-4 lignin model part) mainly by electron transfer leading to guaiacol as major product. Both processes were distance dependent.

Enteric glial-derived S100B protein stimulates nitric oxide production in celiac disease.

PubMed

Esposito, Giuseppe; Cirillo, Carla; Sarnelli, Giovanni; De Filippis, Daniele; D'Armiento, Francesco Paolo; Rocco, Alba; Nardone, Gerardo; Petruzzelli, Raffaella; Grosso, Michela; Izzo, Paola; Iuvone, Teresa; Cuomo, Rosario

2007-09-01

Enteric glia participates to the homeostasis of the gastrointestinal tract. In the central nervous system, increased expression of astroglial-derived S100B protein has been associated with the onset and maintaining of inflammation. The role of enteric glial-derived S100B protein in gastrointestinal inflammation has never been investigated in humans. In this study, we evaluated the expression of S100B and its relationship with nitric oxide production in celiac disease. Duodenal biopsy specimens from untreated and on gluten-free diet patients with celiac disease and controls were respectively processed for S100B and inducible nitric oxide synthase (iNOS) protein expression and nitrite production. To evaluate the direct involvement of S100B in the inflammation, control biopsy specimens were exposed to exogenous S100B, and iNOS protein expression and nitrite production were measured. We also tested gliadin induction of S100B-dependent inflammation in cultured biopsy specimens deriving from on gluten-free diet patients in the absence or presence of the specific S100B antibody. S100B messenger RNA and protein expression, iNOS protein expression, and nitrite production were significantly increased in untreated patients but not in on gluten-free diet patients vs controls. Addition of S100B to control biopsy specimens resulted in a significant increase of iNOS protein expression and nitrite production. In celiac disease patients but not in controls biopsy specimens, gliadin challenge significantly increased S100B messenger RNA and protein expression, iNOS protein expression, and nitrite production, but these effects were completely inhibited by S100B antibody. Enteric glial-derived S100B is increased in the duodenum of patients with celiac disease and plays a role in nitric oxide production.

Molecular mechanisms of action of styrene toxicity in blood plasma and liver.

PubMed

Niaz, Kamal; Mabqool, Faheem; Khan, Fazlullah; Ismail Hassan, Fatima; Baeeri, Maryam; Navaei-Nigjeh, Mona; Hassani, Shokoufeh; Gholami, Mahdi; Abdollahi, Mohammad

2017-10-01

Styrene is an aromatic colorless hydrocarbon available in liquid form and highly volatile. In its pure form, it gives a sweet smell. The primary source of exposure in the environment is from plastic materials, rubber industries, packaging materials, insulations, and fiber glass and carpet industry. Natural sources of styrene include: few metabolites in plants which are transferred through food chain. The current study was designed to evaluate styrene toxicity, including: superoxide dismutase (SOD) and protein carbonyl, oxidative stress, glucose-6-phosphatase (G6Pase), glycogen phosphorylase (GP), and phosphoenolpyruvate carboxykinase (PEPCK) activities, adenosine triphosphate (ATP) to adenosine diphosphate (ADP) ratio, and changes in gene expressions such as glutamate dehydrogenase 1 (GLUD1), glucose transporter 2 (GLUT2), and glucokinase (GCK) in the rat liver tissue. For this purpose, styrene was dissolved in corn oil and was administered via gavage, at doses 250, 500, 1000, 1500, 2000, mg/kg/day per mL and control (corn oil) to each rat with one day off in a week, for 42 days. Plasma SOD and protein carbonyl of plasma were significantly up-regulated in 1000, 1500, and 2000 mg/kg/day styrene administrated groups (P < .001). In addition, styrene caused an increase in lipid peroxidation (LPO) and reactive oxygen species (ROS) in the dose-dependent manners in liver tissue (P < .001). Furthermore, the ferrous reducing antioxidant power (FRAP) and total thiol molecules (TTM) in styrene-treated groups were significantly decreased in liver tissue (P < .001) with increasing doses. In treated rats, styrene significantly increased G6Pase activity (P < .001) and down-regulated GP activity (P < .001) as compared to the control group. The PEPCK activity was significantly raised in a dose-dependent manner (P < .001). The ATP/ADP ratio of live cells was significantly raised by increasing the dose (P < .001). There was significantly an up

Styrene vapor control systems in FRP yacht plants.

PubMed

Todd, W F

1985-01-01

The production of large (greater than 25-ft) fiber-reinforced plastic (FRP) yachts has presented problems of styrene exposure in excess of the Occupational Safety and Health Administration permissible exposure level (OSHA PEL) of 100 ppm. Also, the National Institute for Occupational Safety and Health (NIOSH) is currently recommending a 10-hour workshift, 40-hour workweek time weighted average (TWA) of 50 ppm for styrene. Meeting this challenge will require a system of engineering, work practice, personal protective equipment, and monitoring control measures. NIOSH has performed a study of the engineering controls in three FRP yacht plants. Work practices and the use of personal protective equipment (PPE) were also considered in the evaluation. The three systems evaluated included a dilution system, a local ventilation system, and a push-pull ventilation system. The cost of constructing and operating these systems was not evaluated in this study. Study results indicated that each type of ventilation system can meet the present PEL of 100 ppm styrene; however, it is not certain that these systems can meet a lower PEL of 50 ppm styrene.

Development of Styrene-Grafted Polyurethane by Radiation-Based Techniques

PubMed Central

Jeong, Jin-Oh; Park, Jong-Seok; Lim, Youn-Mook

2016-01-01

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. PMID:28773561

[Degradation of styrene by coupling ultraviolet and biofiltration].

PubMed

Sha, Hao-Lei; Yang, Guo-Jing; Xia, Jing-Fen

2013-12-01

Purification of styrene by ultraviolet (UV)-biofiltration was studied in this paper. The light source and the biofilm carrier were ozone producing lamp at 185 nm and the peat, palm fiber, porous acticarbon, respectively. Styrene inlet concentration was controlled between 320-583 mg x m(-3), and the removal efficiency remained above 95% after stabilization. The UV converted styrene into more soluble and biodegradable intermediates, such as alcohol, aldehyde and acid, thus the performance of biofilter can be improved. In the stable operation stage, the variation of inlet concentration did not affect the removal efficiency when the total residence time (TRT) was long, however, the inlet concentration obviously affected the removal efficiency when the TRT decreased. The removal load of coupling system increased linearly with increasing inlet load, and the removal efficiency was higher than 95% under a TRT of 102 s. When TRT was 68 s and the inlet load was low, the variation of removal load complied with the law described above, but it gradually deviated from the straight line and tended to stabilized at a certain value when the inlet load became higher than 30 g x (m3 x h)(-). If considering the fluctuation of styrene concentration only, the contribution rate of ultraviolet photolysis to styrene removal was greater than that of the biofilter, and the removal effect could be restored on the fourth day, after closing the system for ten days and restarting.

Occupational asthma in the furniture industry: is it due to styrene?

PubMed

Oner, Ferda; Mungan, Dilşad; Numanoglu, Numan; Demirel, Yavuz

2004-01-01

Styrene, a volatile monomer, has been reported as a cause of occupational asthma in a few case reports. The aim of this study was to investigate the risk for asthma in relation to exposure to styrene in a large number of workers. A total of 47 workers with a history of exposure to styrene were included in the study. To establish whether asthma was present, each patient underwent a clinical interview, pulmonary function testing and bronchial challenge with methacholine. Specific bronchial challenges with styrene and serial peak expiratory flow (PEF) measurement at home and at work were carried out in subjects with a diagnosis of asthma to evaluate the relationship between their asthma and exposure to styrene in the workplace. Among the 47 subjects, 5 workers had given a history of work-related symptoms, and 3 of them had a positive methacholine challenge test. Specific bronchial challenges with styrene and serial PEF measurement were subsequently carried out in these 3 subjects. Although provocation tests with styrene were negative in the 3 workers, 1 worker had PEF rate records compatible with occupational asthma. We established one patient with occupational asthma from a group of people who have excessive styrene exposure. This finding may be suggestive but is not conclusive about the causative role of styrene in occupational asthma. Since styrene is a frequently used substance in the furniture industry, it is worth performing further studies to investigate the relationship between styrene and occupational asthma. Copyright 2004 S. Karger AG, Basel

Biomonitoring of styrene occupational exposures: Biomarkers and determinants.

PubMed

Persoons, Renaud; Richard, Justine; Herve, Claire; Montlevier, Sarah; Marques, Marie; Maitre, Anne

2018-06-22

High styrene exposures are still experienced in various occupational settings, requesting regular exposure assessments. The aims of this study were to study occupational exposures in various industrial sectors and to determine factors influencing styrene urinary metabolites levels. Biomonitoring was conducted in 141 workers from fiberglass-reinforced plastic (FRP) manufacture, thermoplastic polymers production, vehicle repair shops and cured-in-place pipe lining (CIPP). Urinary styrene (StyU) as well as Mandelic (MA) / Phenyglyoxylic Acids (PGA) were quantified at the beginning and at the end of week, and multivariate linear regression models were used. StyU levels revealed very low, rarely exceeding 3 µg.L -1 . Highest concentrations of MA + PGA were observed in FRP sector, with levels reaching up to 1100 mg.g -1 of creatinine. Factors influencing end-of-week MA + PGA concentrations were levels at the beginning of week, open molding processes, proximity to the emission source, respiratory protection, styrene content in raw materials. Elevated levels were also observed during CIPP process, whereas thermoplastic injection and vehicle repair shop workers exhibited much lower exposures. Intervention on process (decreasing styrene proportion, using closed molding), protective equipment (local exhaust ventilation, respiratory protection) and individual practices (stringent safety rules) are expected to decrease occupational exposures. Urinary MA + PGA remain the most appropriate biomarkers for occupational biomonitoring. Copyright © 2018. Published by Elsevier B.V.

Highly efficient and selective pressure-assisted photon-induced polymerization of styrene

NASA Astrophysics Data System (ADS)

Guan, Jiwen; Song, Yang

2016-06-01

The polymerization process of condensed styrene to produce polystyrene as an industrially important polymeric material was investigated using a novel approach by combining external compression with ultraviolet radiation. The reaction evolution was monitored as a function of time and the reaction products were characterized by in situ Fourier transform infrared spectroscopy. By optimizing the loading pressures, we observed highly efficient and selective production of polystyrene of different tacticities. Specifically, at relatively low loading pressures, infrared spectra suggest that styrene monomers transform to amorphous atactic polystyrene (APS) with minor crystalline isotactic polystyrene. In contrast, APS was found to be the sole product when polymerization occurs at relatively higher loading pressures. The time-dependent reaction profiles allow the examination of the polymerization kinetics by analyzing the rate constant and activation volume as a function of pressure. As a result, an optimized pressure condition, which allows a barrierless reaction to proceed, was identified and attributed to the very desirable reaction yield and kinetics. Finally, the photoinitiated reaction mechanism and the growth geometry of the polymer chains were investigated from the energy diagram of styrene and by the topology analysis of the crystal styrene. This study shows strong promise to produce functional polymeric materials in a highly efficient and controlled manner.

Synergetic effect of graphene oxide-carbon nanotube on nanomechanical properties of acrylonitrile butadiene styrene nanocomposites

NASA Astrophysics Data System (ADS)

Jyoti, Jeevan; Pratap Singh, Bhanu; Chockalingam, Sreekumar; Joshi, Amish G.; Gupta, Tejendra K.; Dhakate, S. R.

2018-04-01

Herein, multiwall carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), graphene oxide-carbon nanotubes (GCNTs) hybrid reinforced acrylonitrile butadiene styrene (ABS) nanocomposites have been prepared by micro twin screw extruder with back flow channel and the effect of different type of fillers on the nanomechanical properties are studied. The combination of both graphene oxide and CNT has enhanced the dispersion in polymer matrix and lower the probability of CNTs aggregation. GCNTs hybrid have been synthesized via novel chemical route and well characterized using Raman spectroscopic technique. The nanoindentation hardness and elastic modulus of GCNTs-ABS hybrid nanocomposites were improved from 211.3 MPa and 4.12 GPa of neat ABS to 298.9 MPa and 6.02 GPa, respectively at 5wt% GCNTs loading. In addition to hardness and elastic modulus, other mechanical properties i.e. plastic index parameter, elastic recovery, ratio of residual displacement after load removal and displacement at the maximum load and plastic deformation energy have also been investigated. These results were correlated with Raman and X-ray photoelectron spectroscopic (XPS) techniques and microstructural characterizations (scanning electron microscopy). Our demonstration would provide guidelines for the fabrication of hard and scratches nanocomposite materials for potential use in, automotive trim components and bumper bars, carrying cases and electronic industries and electromagnetic interference shielding.

N-terminus determines activity and specificity of styrene monooxygenase reductases.

PubMed

Heine, Thomas; Scholtissek, Anika; Westphal, Adrie H; van Berkel, Willem J H; Tischler, Dirk

2017-12-01

Styrene monooxygenases (SMOs) are two-enzyme systems that catalyze the enantioselective epoxidation of styrene to (S)-styrene oxide. The FADH 2 co-substrate of the epoxidase component (StyA) is supplied by an NADH-dependent flavin reductase (StyB). The genome of Rhodococcus opacus 1CP encodes two SMO systems. One system, which we define as E1-type, displays homology to the SMO from Pseudomonas taiwanensis VLB120. The other system, originally reported as a fused system (RoStyA2B), is defined as E2-type. Here we found that E1-type RoStyB is inhibited by FMN, while RoStyA2B is known to be active with FMN. To rationalize the observed specificity of RoStyB for FAD, we generated an artificial reductase, designated as RoStyBart, in which the first 22 amino acid residues of RoStyB were joined to the reductase part of RoStyA2B, while the oxygenase part (A2) was removed. RoStyBart mainly purified as apo-protein and mimicked RoStyB in being inhibited by FMN. Pre-incubation with FAD yielded a turnover number at 30°C of 133.9±3.5s -1 , one of the highest rates observed for StyB reductases. RoStyBart holo-enzyme switches to a ping-pong mechanism and fluorescence analysis indicated for unproductive binding of FMN to the second (co-substrate) binding site. In summary, it is shown for the first time that optimization of the N-termini of StyB reductases allows the evolution of their activity and specificity. Copyright © 2017 Elsevier B.V. All rights reserved.

Kinetics of styrene in workers from a plastics industry after controlled exposure: a comparison with subjects not previously exposed.

PubMed Central

Löf, A; Lundgren, E; Nordqvist, M B

1986-01-01

Eight male workers from a glass reinforced plastics industry were experimentally exposed for 2 hours to 2.84 mmol/m3 (296 mg/m3) styrene during light physical exercise (50 W). About 63% of the amount supplied (4.6 mmol styrene) was taken up in the body. The arterial blood concentration of styrene reached a relatively stable level of 15 mumol/l at the end of exposure which was about 70% of the blood concentration in a group of volunteers with no previous exposure to solvents. The apparent blood clearance was significantly higher in the occupationally exposed subjects 2.01/h X kg compared with 1.51/h X kg. Contrary to the relatively stable level of styrene at the end of exposure the concentration of non-conjugated styrene glycol increased throughout the exposure and reached about 3 mumol/l in both groups. Like styrene, the non-conjugated styrene glycol seemed to be eliminated faster from the occupationally exposed workers. The blood concentration of styrene-7,8-oxide was low and seldom exceeded the detection limit of 0.02 mumol/l. The results show that long term exposure in a glass reinforced plastics industry may facilitate the metabolism of styrene. PMID:3730303

Efficient asymmetric hydrolysis of styrene oxide catalyzed by Mung bean epoxide hydrolases in ionic liquid-based biphasic systems.

PubMed

Chen, Wen-Jing; Lou, Wen-Yong; Zong, Min-Hua

2012-07-01

The asymmetric hydrolysis of styrene oxide to (R)-1-phenyl-1,2-ethanediol using Mung bean epoxide hydrolases was, for the first time, successfully conducted in an ionic liquid (IL)-containing biphasic system. Compared to aqueous monophasic system, IL-based biphasic systems could not only dissolve the substrate, but also effectively inhibit the non-enzymatic hydrolysis, and therefore markedly improve the reaction efficiency. Of all the tested ILs, the best results were observed in the biphasic system containing C(4)MIM·PF(6), which exhibited good biocompatibility with the enzyme and was an excellent solvent for the substrate. In the C(4)MIM·PF(6)/buffer biphasic system, it was found that the optimal volume ratio of IL to buffer, reaction temperature, buffer pH and substrate concentration were 1/6, 35°C, 6.5 and 100 mM, respectively, under which the initial reaction rate, the yield and the product e.e. were 18.4 mM/h, 49.4% and 97.0%. The biocatalytic process was shown to be feasible on a 500-mL preparative scale. Copyright © 2011 Elsevier Ltd. All rights reserved.

Ecotoxicity hazard assessment of styrene.

PubMed

Cushman, J R; Rausina, G A; Cruzan, G; Gilbert, J; Williams, E; Harrass, M C; Sousa, J V; Putt, A E; Garvey, N A; St Laurent, J P; Hoberg, J R; Machado, M W

1997-07-01

The ecotoxicity of styrene was evaluated in acute toxicity studies of fathead minnows (Pimephales promelas), daphnids (Daphnia magna), amphipods (Hyalella azteca), and freshwater green algae (Selenastrum capricornutum), and a subacute toxicity study of earthworms (Eisenia fostida). Stable exposure levels were maintained in the studies with fathead minnows, daphnids, and amphipods using sealed, flowthrough, serial dilution systems and test vessels. The algae were evaluated in a sealed, static system. The earthworms were exposed in artificial soil which was renewed after 7 days. Styrene concentrations in water and soil were analyzed by gas chromatography with flame ionization detection following extraction into hexane. Test results are based on measured concentrations. Styrene was moderately toxic to fathead minnows, daphnids, and amphipods: fathead minnow: LC50 (96 hr), 10 mg/liter, and NOEC, 4.0 mg/liter; daphnids: EC50 (48 hr), 4.7 mg/liter, and NOEC, 1.9 mg/liter; amphipods: LC50 (96 hr), 9.5 mg/liter, and NOEC, 4.1 mg/liter. Styrene was highly toxic to green algae: EC50 (96 hr), 0.72 mg/liter, and NOEC, 0.063 mg/liter; these effects were found to be algistatic rather than algicidal. Styrene was slightly toxic to earthworms: LC50 (14 days), 120 mg/kg, and NOEC, 44 mg/kg. There was no indication of a concern for chronic toxicity based on these studies. Styrene's potential impact on aquatic and soil environments is significantly mitigated by its volatility and biodegradability.

Influence of temperature on styrene emission from a vinyl ester resin thermoset composite material.

PubMed

Crawford, Shaun; Lungu, Claudiu T

2011-08-15

Composite materials made with vinyl ester resins are lighter, stronger and corrosion resistant compared to most metals, and are increasingly being used as building materials and in public transportation. Styrene monomer is used as both a diluent and strengthener in the production of vinyl ester resin (VER) composites. Some researchers contend that free styrene in VER composites is available to diffuse out of the material into air, perhaps leading to adverse health effects via inhalation exposures in humans, yet there is no known data on styrene emissions from these materials in the literature. In this study, a typical VER composite made with resin containing 38% by weight styrene, reinforced with E-glass fiber and formed using a vacuum assisted resin transfer method was characterized for styrene emissions by environmental test chamber (ETC) methodology. Styrene concentrations in the ETC were measured over a temperature range of 10 to 50 °C. Initial evaporative styrene emissions increase with increasing temperature. There is a nearly linear relationship in the total mass of styrene emitted and emission factor as emissions increase with increasing temperature. Styrene emission factors appear to vary for different materials, which could indicate more complex processes or the influence of material physical properties on emission rates. These results can be used to validate and improve mass transfer emission models for the prediction of volatile organic compound concentrations in indoor environments. Published by Elsevier B.V.

[Studies on the industrial styrene poisoning (Part X). Determination of styrene in biological materials by gas chromatography (author's transl)].

PubMed

Teramoto, K; Horiguchi, S

1980-09-01

For monitoring solvents exposure, it is useful to determine not only metabolites of the solvents in urine but also the solvents themselves in blood and tissues. In a series of studies on the industrial styrene poisoning, we have been determining styrene in blood and other tissues as occasion calls. Our examination of the method is presented in this report. The outline on the method is as follows: Aliquots of 0.5g of tissues being added 5 ml of n-hexane are homogenized by a high-speed homogenizer (Polytoron) for 10 to 30 seconds and the filtrates containing extracts are analyzed for styrene by gas chromatography. The linearity was ascertained from the calibration curve obtained by adding the known quantities of styrene (4, 10, 20, 40, 100 ppm) to the blood, liver and adipose tissues of rats. Rates of recoveries of styrene from the above tissues were 92 to 101 per cent. Reproducibility of this method was examined by repeating determinations of styrene in the blood, liver and adipose tissues of rats exposed to 500 ppm styrene for 4 hours, the coefficients of variation being 2.8 to 14.0 per cent. There was an approximately linear relationship between the styrene concentration (0 to 1,000 ppm) of the exposed air and those in the blood of exposed rats. We conclude that our simple and rapid method is applicable to determination of solvents other than styrene in organs and tissues by combining suitable solvents for extraction and packings of gas chromatography.

Styrene

Integrated Risk Information System (IRIS)

Styrene ; CASRN 100 - 42 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

21 CFR 177.1810 - Styrene block polymers.

Code of Federal Regulations, 2010 CFR

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...

21 CFR 177.1810 - Styrene block polymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false 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...

21 CFR 177.1810 - Styrene block polymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false 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...

21 CFR 177.1810 - Styrene block polymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false 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...

21 CFR 177.1810 - Styrene block polymers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Styrene block polymers. 177.1810 Section 177.1810...) 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 block polymers identified in paragraph (a...

The oxidation of alkylaryl sulfides and benzo[b]thiophenes by Escherichia coli cells expressing wild-type and engineered styrene monooxygenase from Pseudomonas putida CA-3.

PubMed

Nikodinovic-Runic, Jasmina; Coulombel, Lydie; Francuski, Djordje; Sharma, Narain D; Boyd, Derek R; Ferrall, Rory Moore O; O'Connor, Kevin E

2013-06-01

Nine different sulfur-containing compounds were biotransformed to the corresponding sulfoxides by Escherichia coli Bl21(DE3) cells expressing styrene monooxygenase (SMO) from Pseudomonas putida CA-3. Thioanisole was consumed at 83.3 μmoles min(-1) g cell dry weight(-1) resulting mainly in the formation of R-thioanisole sulfoxide with an enantiomeric excess (ee) value of 45 %. The rate of 2-methyl-, 2-chloro- and 2-bromo-thioanisole consumption was 2-fold lower than that of thioanisole. Surprisingly, the 2-methylthioanisole sulfoxide product had the opposite (S) configuration to that of the other 2-substituted thioanisole derivatives and had a higher ee value (84 %). The rate of oxidation of 4-substituted thioanisoles was higher than the corresponding 2-substituted substrates but the ee values of the products were consistently lower (10-23 %). The rate of benzo[b]thiophene and 2-methylbenzo[b]thiophene sulfoxidation was approximately 10-fold lower than that of thioanisole. The ee value of the benzo[b]thiophene sulfoxide could not be determined as the product racemized rapidly. E. coli cells expressing an engineered SMO (SMOeng R3-11) oxidised 2-substituted thioanisoles between 1.8- and 2.8-fold faster compared to cells expressing the wild-type enzyme. SMOeng R3-11 oxidised benzo[b]thiophene and 2-methylbenzo[b]thiophene 10.1 and 5.6 times faster that the wild-type enzyme. The stereospecificity of the reaction catalysed by SMOeng was unchanged from that of the wild type. Using the X-ray crystal structure of the P. putida S12 SMO, it was evident that the entrance of substrates into the SMO active site is limited by the binding pocket bottleneck formed by the side chains of Val-211 and Asn-46 carboxyamide group.

Mortality among styrene-exposed workers in the reinforced plastic boatbuilding industry.

PubMed

Ruder, Avima M; Meyers, Alysha R; Bertke, Stephen J

2016-02-01

We updated mortality through 2011 for 5203 boat-building workers potentially exposed to styrene, and analysed mortality among 1678 employed a year or more between 1959 and 1978. The a priori hypotheses: excess leukaemia and lymphoma would be found. Standardised mortality ratios (SMRs) and 95% CIs and standardised rate ratios (SRRs) used Washington State rates and a person-years analysis programme, LTAS.NET. The SRR analysis compared outcomes among tertiles of estimated cumulative potential styrene exposure. Overall, 598 deaths (SMR=0.96, CI 0.89 to 1.04) included excess lung (SMR=1.23, CI 0.95 to 1.56) and ovarian cancer (SMR 3.08, CI 1.00 to 7.19), and chronic obstructive pulmonary disease (COPD) (SMR=1.15, CI 0.81 to 1.58). Among 580 workers with potential high-styrene exposure, COPD mortality increased 2-fold (SMR=2.02, CI 1.08 to 3.46). COPD was more pronounced among those with potential high-styrene exposure. However, no outcome was related to estimated cumulative styrene exposure, and there was no change when latency was taken into account. We found no excess leukaemia or lymphoma mortality. As in most occupational cohort studies, lack of information on lifestyle factors or other employment was a substantial limitation although we excluded from the analyses those (n=3525) who worked <1 year. Unanticipated excess ovarian cancer mortality could be a chance finding. Comparing subcohorts with potential high-styrene and low-styrene exposure, COPD mortality SRR was elevated while lung cancer SRR was not, suggesting that smoking was not the only cause for excess COPD mortality. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Enhanced conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film by acid treatment for indium tin oxide-free organic solar cells

NASA Astrophysics Data System (ADS)

Lin, Chun-Chiao; Huang, Chih-Kuo; Hung, Yu-Chieh; Chang, Mei-Ying

2016-08-01

An acid treatment is used in the enhancement of the conductivity of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin film, which is often used as the anode in organic solar cells. There are three types of acid treatment for PEDOT:PSS thin film: hydrochloric, sulfuric, and phosphoric acid treatments. In this study, we examine and compare these three ways with each other for differences in conductivity. Hydrochloric acid results in the highest conductivity enhancement, from 0.3 to 1109 S/cm. We also discuss the optical transmittance, conductivity, surface roughness, surface morphology, and stability, as well as the factors that can influence device efficiency. The devices are fabricated using an acid-treated PEDOT:PSS thin film as the anode. The highest power conversion efficiency was 1.32%, which is a large improvement over that of the unmodified organic solar cell (0.21%). It is comparable to that obtained when using indium tin oxide (ITO) as an electrode, ca. 1.46%.

Estrogenic reduction of styrene monomer degraded by Phanerochaete chrysosporium KFRI 20742.

PubMed

Lee, Jae-Won; Lee, Soo-Min; Hong, Eui-Ju; Jeung, Eui-Bae; Kang, Ha-Young; Kim, Myung-Kil; Choi, In-Gyu

2006-04-01

The characteristic biodegradation of monomeric styrene by Phanerochaete chrysosporium KFRI 20742, Trametes versicolor KFRI 20251 and Daldinia concentrica KFRI 40-1 was carried out to examine the resistance, its degradation efficiency and metabolites analysis. The estrogenic reduction effect of styrene by the fungi was also evaluated. The mycelium growth of fungi differentiated depending on the concentration levels of styrene. Additionally P. chrysosporium KFRI 20742 showed superior mycelium growth at less than 200 mg/l, while D. concentrica KFRI 40-1 was more than 200 mg/l. The degradation efficiency reached 99% during one day of incubation for all the fungi. Both manganese-dependent peroxidase and laccase activities in liquid medium were the highest at the initial stage of incubation, whereas the lowest was after the addition of styrene. However, both activities were gradually recovered after. The major metabolites of styrene by P. chrysosporium KFRI 20742 were 2-phenyl ethanol, benzoic acid, cyclohexadiene-1,4-dione, butanol and succinic acid. From one to seven days of incubating the fungi, the expression of pS2 mRNA widely known as an estrogen response gene was decreased down to the level of baseline after one day. Also, the estrogenic effect of styrene completely disappeared after treatment with supernatant of P. chrysosporium KFRI 20742 from one week of culture down to the levels of vehicle.

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

PubMed

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.

Trends in Occupational Exposure to Styrene in the European Glass Fibre-Reinforced Plastics Industry

PubMed Central

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

2008-01-01

Aim: This study presents temporal trends of styrene exposure for workers in the European glass fibre-reinforced plastics (GRP) industry during the period 1966–2002. Methods: 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. Results: 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. PMID:18550625

Stable-isotope-based labeling of styrene-degrading microorganisms in biofilters.

PubMed

Alexandrino, M; Knief, C; Lipski, A

2001-10-01

Deuterated styrene ([(2)H(8)]styrene) was used as a tracer in combination with phospholipid fatty acid (PLFA) analysis for characterization of styrene-degrading microbial populations of biofilters used for treatment of waste gases. Deuterated fatty acids were detected and quantified by gas chromatography-mass spectrometry. The method was evaluated with pure cultures of styrene-degrading bacteria and defined mixed cultures of styrene degraders and non-styrene-degrading organisms. Incubation of styrene degraders for 3 days with [(2)H(8)]styrene led to fatty acids consisting of up to 90% deuterated molecules. Mixed-culture experiments showed that specific labeling of styrene-degrading strains and only weak labeling of fatty acids of non-styrene-degrading organisms occurred after incubation with [(2)H(8)]styrene for up to 7 days. Analysis of actively degrading filter material from an experimental biofilter and a full-scale biofilter by this method showed that there were differences in the patterns of labeled fatty acids. For the experimental biofilter the fatty acids with largest amounts of labeled molecules were palmitic acid (16:0), 9,10-methylenehexadecanoic acid (17:0 cyclo9-10), and vaccenic acid (18:1 cis11). These lipid markers indicated that styrene was degraded by organisms with a Pseudomonas-like fatty acid profile. In contrast, the most intensively labeled fatty acids of the full-scale biofilter sample were palmitic acid and cis-11-hexadecenoic acid (16:1 cis11), indicating that an unknown styrene-degrading taxon was present. Iso-, anteiso-, and 10-methyl-branched fatty acids showed no or weak labeling. Therefore, we found no indication that styrene was degraded by organisms with methyl-branched fatty fatty acids, such as Xanthomonas, Bacillus, Streptomyces, or Gordonia spp.

[Changes in the peripheral blood of workers engaged in ethylbenzene-styrene and synthetic rubber and latex manufacture].

PubMed

Khristeva, V

1986-01-01

A total of 67 workers were examined from the production of "Ethyl benzene-styrene" and 184 workers from the production of "Synthetic rubber and latex", as well as a control group of 59 employees. The workers from the first production are exposed to the effect of styrene, ethyl benzene and toluene. The concentrations of the substances surpass MAC, with several times, at the majority of the working places. The workers with a length of service over 10 years predominate. The workers from the second production are exposed to the combined effect of styrene and divinyl, their concentrations fluctuating from 2 to 8 times over MAC. The workers with a length of service over 10 years are 71.7%. The deviations, established in the hematological indices studied are compared with the results from a study on the workers from those productions of 6 years ago. Dynamics in the changes was established among the workers from the production of "Synthetic rubber and latex", associated with the duration of occupational exposure to styrene and divinyl. In case of a shorter length of service, the deviations are functional (reduction of peroxidase activity in granulocytes), increase of hemoglobin and hematocrit, associated with the adaptive reaction of organism. Pronounced anemic syndrome was established in a considerable number (24 workers) after an exposure of 10 years as well as lymphocytosis (35 subjects) and leukopenia (9 subjects).

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

PubMed

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 < 0.0001). A non-significant Cochran's Q test result (Q = 23.2; P = 0.171) and an I 2 of 32.2% (0.0%, 69.9%) indicated low-to-moderate between-study heterogeneity. Funnel plot and trim-and-fill analyses suggested publication bias. This review confirms the hypothesis of occupational styrene-induced dyschromatopsia, suggesting a modest effect size with mild heterogeneity between studies. © 2017 Wiley Periodicals, Inc.

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

PubMed

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.

Kinetics of styrene biodegradation by Pseudomonas sp. E-93486.

PubMed

Gąszczak, Agnieszka; Bartelmus, Grażyna; Greń, Izabela

2012-01-01

The research into kinetics of styrene biodegradation by bacterial strain Pseudomonas sp. E-93486 coming from VTT Culture Collection (Finland) was presented in this work. Microbial growth tests in the presence of styrene as the sole carbon and energy source were performed both in batch and continuous cultures. Batch experiments were conducted for initial concentration of styrene in the liquid phase changed in the range of 5-90 g m(-3). The Haldane model was found to be the best to fit the kinetic data, and the estimated constants of the equation were: μ (m) = 0.1188 h(-1), K(S) = 5.984 mg l(-1), and K (i) = 156.6 mg l(-1). The yield coefficient mean value [Formula in text] for the batch culture was 0.72 g(dry cells weight) (g(substrate))(-1). The experiments conducted in a chemostat at various dilution rates (D = 0.035-0.1 h(-1)) made it possible to determine the value of the coefficient for maintenance metabolism m (d) = 0.0165 h(-1) and the maximum yield coefficient value [Formula in text]. Chemostat experiments confirmed the high value of yield coefficient [Formula in text] observed in the batch culture. The conducted experiments showed high activity of the examined strain in the styrene biodegradation process and a relatively low sensitivity to inhibition of its growth at higher concentrations of styrene in the solution. Such exceptional features of Pseudomonas sp. E-93486 make this bacterial strain the perfect candidate for technical applications.

Predominant 1,2-insertion of styrene in the Pd-catalyzed alternating copolymerization with carbon monoxide.

PubMed

Nozaki, K; Komaki, H; Kawashima, Y; Hiyama, T; Matsubara, T

2001-01-31

The regioselectivity of styrene insertion to an acyl-Pd bond was studied by NMR in (i) a stoichiomeric reaction and (ii) a copolymerization with CO. In the stoichiometric reaction of styrene with [(CH(3)CO)Pd(CH(3)CN)[(R,S)-BINAPHOS

21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... will pass through a U.S. standard sieve No. 10 and will be held on a U.S. standard sieve No. 20 0.02... sieve No. 10 and will be held on a U.S. standard sieve No. 20. 2. Styrene-maleic anhydride copolymer... particles of a size that will pass through a U.S. standard sieve No. 10 and will be held on a U.S. standard...

21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... will pass through a U.S. standard sieve No. 10 and will be held on a U.S. standard sieve No. 20 0.02... sieve No. 10 and will be held on a U.S. standard sieve No. 20. 2. Styrene-maleic anhydride copolymer... particles of a size that will pass through a U.S. standard sieve No. 10 and will be held on a U.S. standard...

Flavone inhibits nitric oxide synthase (NOS) activity, nitric oxide production and protein S-nitrosylation in breast cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Wenzhen; Yang, Bingwu; Fu, Huiling

As the core structure of flavonoids, flavone has been proved to possess anticancer effects. Flavone's growth inhibitory functions are related to NO. NO is synthesized by nitric oxide synthase (NOS), and generally increased in a variety of cancer cells. NO regulates multiple cellular responses by S-nitrosylation. In this study, we explored flavone-induced regulations on nitric oxide (NO)-related cellular processes in breast cancer cells. Our results showed that, flavone suppresses breast cancer cell proliferation and induces apoptosis. Flavone restrains NO synthesis by does-dependent inhibiting NOS enzymatic activity. The decrease of NO generation was detected by fluorescence microscopy and flow cytometry. Flavone-inducedmore » inhibitory effect on NOS activity is dependent on intact cell structure. For the NO-induced protein modification, flavone treatment significantly down-regulated protein S-nitrosylation, which was detected by “Biotin-switch” method. The present study provides a novel, NO-related mechanism for the anticancer function of flavone. - Highlights: • Flavone inhibits proliferation and induces apoptosis in MCF-7 cells. • Flavone decreases nitric oxide production by inhibiting NOS enzymatic activity in breast cancer cells. • Flavone down-regulates protein S-nitrosylation.« less

21 CFR 573.870 - Poly(2-vinylpyridine-co-styrene).

Code of Federal Regulations, 2013 CFR

2013-04-01

... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.870 Poly(2-vinylpyridine-co-styrene). The food additive poly(2... the Federal Food, Drug, and Cosmetic Act, the following: (1) The name of the additive. (2) A statement...

21 CFR 573.870 - Poly(2-vinylpyridine-co-styrene).

Code of Federal Regulations, 2014 CFR

2014-04-01

... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.870 Poly(2-vinylpyridine-co-styrene). The food additive poly(2... the Federal Food, Drug, and Cosmetic Act, the following: (1) The name of the additive. (2) A statement...

21 CFR 573.870 - Poly(2-vinylpyridine-co-styrene).

Code of Federal Regulations, 2011 CFR

2011-04-01

... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.870 Poly(2-vinylpyridine-co-styrene). The food additive poly(2... the Federal Food, Drug, and Cosmetic Act, the following: (1) The name of the additive. (2) A statement...

21 CFR 573.870 - Poly(2-vinylpyridine-co-styrene).

Code of Federal Regulations, 2012 CFR

2012-04-01

... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.870 Poly(2-vinylpyridine-co-styrene). The food additive poly(2... the Federal Food, Drug, and Cosmetic Act, the following: (1) The name of the additive. (2) A statement...

21 CFR 573.870 - Poly(2-vinylpyridine-co-styrene).

Code of Federal Regulations, 2010 CFR

2010-04-01

... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.870 Poly(2-vinylpyridine-co-styrene). The food additive poly(2... the Federal Food, Drug, and Cosmetic Act, the following: (1) The name of the additive. (2) A statement...

Styrene-Associated Health Outcomes at a Windblade Manufacturing Plant

PubMed Central

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

Cancer mortality in an international cohort of reinforced plastics workers exposed to styrene: a reanalysis.

PubMed

Loomis, Dana; Guha, Neela; Kogevinas, Manolis; Fontana, Vincenzo; Gennaro, Valerio; Kolstad, Henrik A; McElvenny, Damien Martin; Sallmén, Markku; Saracci, Rodolfo

2018-04-17

To investigate the carcinogenicity of styrene by reanalysing data from a previous international cohort study of workers in the reinforced plastics industry. Mortality from cancers of prior interest was analysed with more detailed consideration of exposure-response relations and an updated classification of leukaemias and lymphomas in data from a previous international cohort study of 37 021 reinforced plastics workers exposed to airborne styrene. Increased mortality from non-Hodgkin's lymphoma (NHL) was associated with the mean level of exposure to styrene in air (relative risk (RR) 2.31, 95% CI 1.29 to 4.12 per 100 ppm), but not with cumulative styrene exposure. Similar associations with mean exposure were observed for the oesophagus (RR 2.44, 95% CI 1.11 to 5.36 per 100 ppm) and pancreas (RR 1.89, 95% CI 1.17 to 3.09). Oesophageal cancer mortality was also associated with cumulative styrene exposure lagged 20 years (RR 1.16, 95% CI 1.03 to 1.31). No other cancer, including lung cancer, was associated with any indicator of styrene exposure. This reanalysis does not substantially change the conclusions of the original study with respect to NHL or lung cancer but new evidence concerning cancers of the oesophagus and pancreas merits further investigation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Production of Manganese Oxide Nanoparticles by Shewanella Species

PubMed Central

Farooqui, Saad M.; White, Alan R.

2016-01-01

ABSTRACT Several species of the bacterial genus Shewanella are well-known dissimilatory reducers of manganese under anaerobic conditions. In fact, Shewanella oneidensis is one of the most well studied of all metal-reducing bacteria. In the current study, a number of Shewanella strains were tested for manganese-oxidizing capacity under aerobic conditions. All were able to oxidize Mn(II) and to produce solid dark brown manganese oxides. Shewanella loihica strain PV-4 was the strongest oxidizer, producing oxides at a rate of 20.3 mg/liter/day and oxidizing Mn(II) concentrations of up to 9 mM. In contrast, S. oneidensis MR-1 was the weakest oxidizer tested, producing oxides at 4.4 mg/liter/day and oxidizing up to 4 mM Mn(II). Analysis of products from the strongest oxidizers, i.e., S. loihica PV-4 and Shewanella putrefaciens CN-32, revealed finely grained, nanosize, poorly crystalline oxide particles with identical Mn oxidation states of 3.86. The biogenic manganese oxide products could be subsequently reduced within 2 days by all of the Shewanella strains when culture conditions were made anoxic and an appropriate nutrient (lactate) was added. While Shewanella species were detected previously as part of manganese-oxidizing consortia in natural environments, the current study has clearly shown manganese-reducing Shewanella species bacteria that are able to oxidize manganese in aerobic cultures. IMPORTANCE Members of the genus Shewanella are well known as dissimilatory manganese-reducing bacteria. This study shows that a number of species from Shewanella are also capable of manganese oxidation under aerobic conditions. Characterization of the products of the two most efficient oxidizers, S. loihica and S. putrefaciens, revealed finely grained, nanosize oxide particles. With a change in culture conditions, the manganese oxide products could be subsequently reduced by the same bacteria. The ability of Shewanella species both to oxidize and to reduce manganese indicates

Styrene-butadiene latex modifiers for bridge deck overlay concrete.

DOT National Transportation Integrated Search

1978-04-01

Styrene-butadiene (S/B) latex modified concrete overlays are being used to protect : new bridge decks from rapid deicer-borne chloride intrusion and also in bridge : deck rehabilitation efforts. The purposes of this research were to evaluate several ...

Transformations of Aromatic Compounds by Nitrosomonas europaea

PubMed Central

Keener, William K.; Arp, Daniel J.

1994-01-01

Benzene and a variety of substituted benzenes inhibited ammonia oxidation by intact cells of Nitrosomonas europaea. In most cases, the inhibition was accompanied by transformation of the aromatic compound to a more oxidized product or products. All products detected were aromatic, and substituents were often oxidized but were not separated from the benzene ring. Most transformations were enhanced by (NH4)2SO4 (12.5 mM) and were prevented by C2H2, a mechanism-based inactivator of ammonia monooxygenase (AMO). AMO catalyzed alkyl substituent hydroxylations, styrene epoxidation, ethylbenzene desaturation to styrene, and aniline oxidation to nitrobenzene (and unidentified products). Alkyl substituents were preferred oxidation sites, but the ring was also oxidized to produce phenolic compounds from benzene, ethylbenzene, halobenzenes, phenol, and nitrobenzene. No carboxylic acids were identified. Ethylbenzene was oxidized via styrene to two products common also to oxidation of styrene; production of styrene is suggestive of an electron transfer mechanism for AMO. Iodobenzene and 1,2-dichlorobenzene were oxidized slowly to halophenols; 1,4-dichlorobenzene was not transformed. No 2-halophenols were detected as products. Several hydroxymethyl (-CH2OH)-substituted aromatics and p-cresol were oxidized by C2H2-treated cells to the corresponding aldehydes, benzaldehyde was reduced to benzyl alcohol, and o-cresol and 2,5-dimethylphenol were not depleted. PMID:16349282

Enhanced styrene recovery from waste polystyrene pyrolysis using response surface methodology coupled with Box-Behnken design.

PubMed

Mo, Yu; Zhao, Lei; Wang, Zhonghui; Chen, Chia-Lung; Tan, Giin-Yu Amy; Wang, Jing-Yuan

2014-04-01

A work applied response surface methodology coupled with Box-Behnken design (RSM-BBD) has been developed to enhance styrene recovery from waste polystyrene (WPS) through pyrolysis. The relationship between styrene yield and three selected operating parameters (i.e., temperature, heating rate, and carrier gas flow rate) was investigated. A second order polynomial equation was successfully built to describe the process and predict styrene yield under the study conditions. The factors identified as statistically significant to styrene production were: temperature, with a quadratic effect; heating rate, with a linear effect; carrier gas flow rate, with a quadratic effect; interaction between temperature and carrier gas flow rate; and interaction between heating rate and carrier gas flow rate. The optimum conditions for the current system were determined to be at a temperature range of 470-505°C, a heating rate of 40°C/min, and a carrier gas flow rate range of 115-140mL/min. Under such conditions, 64.52% WPS was recovered as styrene, which was 12% more than the highest reported yield for reactors of similar size. It is concluded that RSM-BBD is an effective approach for yield optimization of styrene recovery from WPS pyrolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enantiomeric fraction of styrene glycol as a biomarker of occupational risk exposure to styrene.

PubMed

Lima, J J; Aguilar, A; Sánchez, F G; Díaz, A N

2017-02-01

This work reports a new analytical approach for monitoring the enantiomeric ratios of styrene glycol (SG), encountered during the manufacture of plastics, by chiral liquid chromatography and the application as a biomarker for exposure to styrene. The isomers were separated using an AGP column running in the reverse phase and isocratic mode with a mobile phase consisting of 20 mM phosphate buffer saline (pH 4.15) and methanol at a flow rate of 0.8 mL/min. Photometric, polarimetric, and circular dichroism detectors were employed. The chromatographic enantioselective resolution (Rs) and selectivity index (α) values were determined to be 1.60 and 1.48 (by photometric detection), respectively. Calibration curves used for the quantification of the SG enantiomers were linear with a correlation coefficient >0.99; the detection limits were in the range of 0.03-0.16 μg, depending on the detector used. Recovery assays on synthetic samples (in triplicate) covering the full range of enantiomeric fractions (0.0-1.0) show accuracy values below 5% for the enantiomeric fraction (EF) in every case. An alternative method based on the measurement of anisotropy factors for the determination of EF, which is faster and does not require the separation of enantiomers, has also been developed. The enantiomeric excess of the toxicant biomarker styrene glycol has been determined. No previous direct enantioselective determination of styrene glycol was published. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photoactuation behavior of styrene-b-isoprene-b-styrene filled with covalently modified carbon nanotubes

NASA Astrophysics Data System (ADS)

Mosnáček, Jaroslav; Ilčíková, Markéta; Chorvát, Dušan; Czaniková, Klaudia; Krupa, Igor

2012-07-01

Styrene-b-isoprene-b-styrene (Kraton) was used as polymer matrix for preparation of multiwall carbon nanotubes (MWCNT) based nanocomposites. In order to suppress aggregation of the he carbon nanotubes and to improve the interations with the Kraton matrix, the MWCNT were modified with cholesteryl molecules and/or polystyrene chains. The effect of the modification on the composite materials was evaluated by using DMTA. The nanocomposite materials were thermoformed to achieve Braille text elements and their elastic response to light (photoactuation) was tested by atomic force microscopy in a contact mode.

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

PubMed

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.

Comparison of DNA-Reactive Metabolites from Nitrosamine and Styrene Using Voltammetric DNA/Microsomes Sensors

PubMed Central

Krishnan, Sadagopan; Bajrami, Besnik; Mani, Vigneshwaran; Pan, Shenmin; Rusling, James F.

2012-01-01

Voltammetric sensors made with films of polyions, double-stranded DNA and liver microsomes adsorbed layer-by-layer onto pyrolytic graphite electrodes were evaluated for reactive metabolite screening. This approach features simple, inexpensive screening without enzyme purification for applications in drug or environmental chemical development. Cytochrome P450 enzymes (CYPs) in the liver microsomes were activated by an NADPH regenerating system or by electrolysis to metabolize model carcinogenic compounds nitrosamine and styrene. Reactive metabolites formed in the films were trapped as adducts with nucleobases on DNA. The DNA damage was detected by square-wave voltammetry (SWV) using Ru(bpy)32+ as a DNA-oxidation catalyst. These sensors showed a larger rate of increase in signal vs. reaction time for a highly toxic nitrosamine than for the moderately toxic styrene due to more rapid reactive metabolite-DNA adduct formation. Results were consistent with reported in vivo TD50 data for the formation of liver tumors in rats. Analogous polyion/ liver microsome films prepared on 500 nm silica nanoparticles (nanoreactors) and reacted with nitrosamine or styrene, provided LC-MS or GC analyses of metabolite formation rates that correlated well with sensor response. PMID:23100998

A Toxicological Framework for the Prioritization of Children’s Safe Product Act Data

PubMed Central

Smith, Marissa N.; Grice, Joshua; Cullen, Alison; Faustman, Elaine M.

2016-01-01

In response to concerns over hazardous chemicals in children’s products, Washington State passed the Children’s Safe Product Act (CSPA). CSPA requires manufacturers to report the concentration of 66 chemicals in children’s products. We describe a framework for the toxicological prioritization of the ten chemical groups most frequently reported under CSPA. The framework scores lifestage, exposure duration, primary, secondary and tertiary exposure routes, toxicokinetics and chemical properties to calculate an exposure score. Four toxicological endpoints were assessed based on curated national and international databases: reproductive and developmental toxicity, endocrine disruption, neurotoxicity and carcinogenicity. A total priority index was calculated from the product of the toxicity and exposure scores. The three highest priority chemicals were formaldehyde, dibutyl phthalate and styrene. Elements of the framework were compared to existing prioritization tools, such as the United States Environmental Protection Agency’s (EPA) ExpoCast and Toxicological Prioritization Index (ToxPi). The CSPA framework allowed us to examine toxicity and exposure pathways in a lifestage-specific manner, providing a relatively high throughput approach to prioritizing hazardous chemicals found in children’s products. PMID:27104547

Evaluation of pollution prevention options to reduce styrene emissions from fiber-reinforced plastic open molding processes.

PubMed

Nunez, C M; Ramsey, G H; Kong, E J; Bahner, M A; Wright, R S; Clayton, C A; Baskir, J N

1999-03-01

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 meet this need, the U.S. Environmental Protection Agency's (EPA) Air Pollution Prevention and Control Division, working in collaboration with Research Triangle Institute, measured styrene emissions for several of these P2 options. In addition, the emission factors calculated from these test results were compared with the existing EPA emission factors for gel coat sprayup and resin applications. Results show that styrene emissions can be reduced by up to 52% by using controlled spraying (i.e., reducing overspray), low-styrene and styrene-suppressed materials, and nonatomizing application equipment. Also, calculated emission factors were 1.6-2.5 times greater than the mid-range EPA emission factors for the corresponding gel coat and resin application. These results indicate that facilities using existing EPA emission factors to estimate emissions in open molding processes are likely to underestimate actual emissions. Facilities should investigate the applicability and feasibility of these P2 options to reduce their styrene emissions.

Using graphene/styrene-isoprene-styrene copolymer composite thin film as a flexible microstrip antenna for the detection of heptane vapors

NASA Astrophysics Data System (ADS)

Olejnik, Robert; Matyas, Jiri; Slobodian, Petr; Riha, Pavel

2018-03-01

Most portable devices, such as mobile phones or tablets, use antennas made of copper. This paper demonstrates the possible use of antenna constructed from electrically conductive polymer composite materials for use in those applications. The method of preparation and the properties of the graphene/styrene-isoprene-styrene copolymer as flexible microstrip antenna are described in this contribution. Graphene/styrene-isoprene-styrene copolymer toluene solution was prepared by means of ultrasound and the PET substrate was dip coated to reach a fine thin film. The main advantages of using PET as a substrate are low weight and flexibility. The final size of the flexible microstrip antenna was 10 × 25 mm with thickness of 0.48 mm (PET substrate 0.25 mm) with a weight of 0.110 g. The resulting antenna operates at a frequency of 1.8 GHz and gain ‑40.02 dB.

Water requirements of the styrene, butadiene and synthetic-rubber industries

USGS Publications Warehouse

Durfor, Charles N.

1963-01-01

withdrawn was discharged to surface waters; the warmed salty waters were returned to their source. The remaining 3 percent, or about 23.6 mgd, of makeup water was used consumptively. The styrene industry consumptively used about 2.0 percent of its intake; the butadiene industry, about 4.5 percent; the specialty-rubber industry, about 9.1 percent; and the SBR industry, about 11 percent. The water shipped in the synthetic-rubber products increased the consumptive use of water by these industries.

CASE-COHORT STUDY OF STYRENE EXPOSURE AND ISCHEMIC HEART DISEASE INVESTIGATORS

EPA Science Inventory

Investigators examined workers exposed to styrene while working in styrene-butadiene polymer manufacturing plants between 1943 and 1982. Workers who had died from ischemic heart disease were compared to a subgroup of all men employed in two styrene-butadiene polymer manufac...

Biofiltration of mixtures of gas-phase styrene and acetone with the fungus Sporothrix variecibatus.

PubMed

Rene, Eldon R; Spačková, Radka; Veiga, María C; Kennes, Christian

2010-12-15

The biodegradation performance of a biofilter, inoculated with the fungus Sporothrix variecibatus, to treat gas-phase styrene and acetone mixtures under steady-state and transient conditions was evaluated. Experiments were carried out by varying the gas-flow rates (0.05-0.4m(3)h(-1)), leading to empty bed residence times as low as 17.1s, and by changing the concentrations of gas-phase styrene (0.01-6.3 g m(-3)) and acetone (0.01-8.9 g m(-3)). The total elimination capacities were as high as 360 g m(-3)h(-1), with nearly 97.5% removal of styrene and 75.6% for acetone. The biodegradation of acetone was inhibited by the presence of styrene, while styrene removal was affected only slightly by the presence of acetone. During transient-state experiments, increasing the overall pollutant load by almost 3-fold, i.e., from 220 to 600 g m(-3)h(-1), resulted in a sudden drop of removal efficiency (>90-70%), but still high elimination capacities were maintained. Periodic microscopic observations revealed that the originally inoculated Sporothrix sp. remained present in the reactor and actively dominant in the biofilm. Copyright © 2010 Elsevier B.V. All rights reserved.

21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1830 Styrene-methyl methacrylate copolymers. Styrene-methyl... intended for use in contact with food, subject to the provisions of this section. (a) For the purpose of...

54 FR 38044: National Emission Standards for Hazardous Air Pollutants; Benzene Emissions From Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By- Product Recovery Plants

EPA Pesticide Factsheets

Final Rule on National Emission Standards for Hazardous Air Pollutants; Benzene Emissions From Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By-Product Recovery Plants.

Enhanced interfacial interaction and antioxidative behavior of novel halloysite nanotubes/silica hybrid supported antioxidant in styrene-butadiene rubber

NASA Astrophysics Data System (ADS)

Lin, Jing; Luo, Yuanfang; Zhong, Bangchao; Hu, Dechao; Jia, Zhixin; Jia, Demin

2018-05-01

A novel antioxidant (HS-s-RT) to improve the mechanical properties and anti-aging performance of styrene-butadiene (SBR) composites was prepared by antioxidant intermediate p-aminodiphenylamine (RT) grafting on the surface of halloysite nanotubes/silica hybrid (HS) via the linkage of silane coupling agent. The analysis of SEM and rubber processing analyzer (RPA) demonstrated HS-s-RT was uniformly dispersed in SBR, and stronger interfacial interaction between HS-s-RT and SBR was formed. Consequently, SBR/HS-s-RT composites have improving mechanical properties. Furthermore, the test of the retention of mechanical properties, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), and oxidation induction time (OIT) showed HS-s-RT can effectively improve the anti-aging effect of SBR composites than corresponding low molecular-weight antioxidant N-isopropyl-N‧-phenyl-4-phenylenediamin (4010NA). Then, the mechanism of thermo-oxidative aging of SBR/HS composites was also investigated, and the superior antioxidative efficiency is attributed to the uniform dispersion and excellent migration resistance of HS-s-RT. Hence, this novel antioxidant might open up new opportunities for the fabrication of high-performance rubber composites due to its superior anti-aging effect and reinforcement.

Organocatalytic atroposelective synthesis of axially chiral styrenes

NASA Astrophysics Data System (ADS)

Zheng, Sheng-Cai; Wu, San; Zhou, Qinghai; Chung, Lung Wa; Ye, Liu; Tan, Bin

2017-05-01

Axially chiral compounds are widespread in biologically active compounds and are useful chiral ligands or organocatalysts in asymmetric catalysis. It is well-known that styrenes are one of the most abundant and principal feedstocks and thus represent excellent prospective building blocks for chemical synthesis. Driven by the development of atroposelective synthesis of axially chiral styrene derivatives, we discovered herein the asymmetric organocatalytic approach via direct Michael addition reaction of substituted diones/ketone esters/malononitrile to alkynals. The axially chiral styrene compounds were produced with good chemical yields, enantioselectivities and almost complete E/Z-selectivities through a secondary amine-catalysed iminium activation strategy under mild conditions. Such structural motifs are important precursors for further transformations into biologically active compounds and synthetic useful intermediates and may have potential applications in asymmetric synthesis as olefin ligands or organocatalysts.

21 CFR 177.1050 - Acrylonitrile/styrene copoly-mer modified with butadiene/styrene elastomer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... parts by weight of a grafted rubber consisting of (i) 8-12 parts of butadiene/styrene elastomer... limitations are determined by an infrared spectro-photo-metric method titled “Infrared Spectro-photo-metric...

Sulfonated Styrene-(ethylene-co-butylene)-styrene/Montmorillonite Clay Nanocomposites: Synthesis, Morphology, and Properties

PubMed Central

2008-01-01

Sulfonated styrene-(ethylene-butylene)-styrene triblock copolymer (SSEBS) was synthesized by reaction of acetyl sulfate with SEBS. SSESB-clay nanocomposites were then prepared from hydrophilic Na-montmorillonite (MT) and organically (quaternary amine) modified hydrophobic nanoclay (OMT) at very low loading. SEBS did not show improvement in properties with MT-based nanocomposites. On sulfonation (3 and 6 weight%) of SEBS, hydrophilic MT clay-based nanocomposites exhibited better mechanical, dynamic mechanical, and thermal properties, and also controlled water–methanol mixture uptake and permeation and AC resistance. Microstructure determined by X-ray diffraction, atomic force microscopy, and transmission electron microscopy due to better dispersion of MT nanoclay particles and interaction of MT with SSEBS matrix was responsible for this effect. The resulting nanocomposites have potential as proton transfer membranes for Fuel Cell applications.

Comparative acute toxicity of leachates from plastic products made of polypropylene, polyethylene, PVC, acrylonitrile-butadiene-styrene, and epoxy to Daphnia magna.

PubMed

Lithner, Delilah; Nordensvan, Ildikó; Dave, Göran

2012-06-01

The large global production of plastics and their presence everywhere in the society and the environment create a need for assessing chemical hazards and risks associated with plastic products. The aims of this study were to determine and compare the toxicity of leachates from plastic products made of five plastics types and to identify the class of compounds that is causing the toxicity. Selected plastic types were those with the largest global annual production, that is, polypropylene, polyethylene, and polyvinyl chloride (PVC), or those composed of hazardous monomers (e.g., PVC, acrylonitrile-butadiene-styrene [ABS], and epoxy). Altogether 26 plastic products were leached in deionized water (3 days at 50°C), and the water phases were tested for acute toxicity to Daphnia magna. Initial Toxicity Identification Evaluations (C18 filtration and EDTA addition) were performed on six leachates. For eleven leachates (42%) 48-h EC50s (i.e the concentration that causes effect in 50 percent of the test organisms) were below the highest test concentration, 250 g plastic/L. All leachates from plasticized PVC (5/5) and epoxy (5/5) products were toxic (48-h EC50s ranging from 2 to 235 g plastic/L). None of the leachates from polypropylene (5/5), ABS (5/5), and rigid PVC (1/1) products showed toxicity, but one of the five tested HDPE leachates was toxic (48-h EC50 17-24 g plastic/L). Toxicity Identification Evaluations indicated that mainly hydrophobic organics were causing the toxicity and that metals were the main cause for one leachate (metal release was also confirmed by chemical analysis). Toxic chemicals leached even during the short-term leaching in water, mainly from plasticized PVC and epoxy products.

Selectivity switch for nitrogen functionalization of styrene on Au(1 1 1)

NASA Astrophysics Data System (ADS)

Deng, Xingyi; Friend, Cynthia M.

2008-03-01

Functionalization of styrene to form N-containing hydrocarbons, e.g. 2-phenylaziridine, benzonitrile, and benzyl nitrile, is achieved by reaction with adsorbed NH a and N a on Au(1 1 1). Electron-induced decomposition of condensed NH 3 was used to produce NH a, N a and H a on Au(1 1 1) at 110 K. The selectivity of the reactions is strongly dependent on the relative concentrations of the surface species. The addition of NH to styrene results in the production of 2-phenylaziridine, whereas adsorbed N and H atoms lead to the formation of nitriles benzonitrile and benzyl nitrile and, respectively, ethylbenzene. This work clearly establishes the utility of Au for promoting functionalization of olefins with nitrogen.

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

Code of Federal Regulations, 2010 CFR

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...

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

The high-temperature oxidation of aromatic hydrocarbons

NASA Technical Reports Server (NTRS)

Brezinsky, K.

1986-01-01

Chemical mechanisms of the atmospheric pressure, high-temperature (875-1500 K) gas-phase oxidation of benzene, toluene, ethylbenzene, and propylbenzene are described and discussed. Oxidation trends evident from turbulent flow reactor experiments serve as the basis for the mechanisms of the oxidation of benzene and alkylated aromatics. The potential effects of very high temperatures and pressures on the chemistry of oxidation of aromatics are described. The oxidation of benzene and phenyl radical has been found to proceed in a stepwise C6-C5-C4 sequence. Species profiles obtained from flow-reactor experiments suggest that the oxidation of benzene and phenyl radical follows the generalized route via phenoxy, cyclopentadienyl and butadienyl radical. The oxidation of the C4 species branches into multiple pathways that yield copious amounts of ethylene and acetylene. Certain major trends are evident: the alkylated aromatics on initial attack either form styrene, benzyl radical or benzene. The styrene reacts further to produce a benzyl radical or benzene. The oxidation of an alkylated aromatic hydrocarbon appears eventually to reduce to the oxidation of either phenyl radical or benzene.

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

Code of Federal Regulations, 2010 CFR

2010-07-01

... 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... as modified styrene, divinylbenzene polymer (PMN P-07-642) is subject to reporting under this section...

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... 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... as modified styrene, divinylbenzene polymer (PMN P-07-642) is subject to reporting under this section...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

... 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... as modified styrene, divinylbenzene polymer (PMN P-07-642) is subject to reporting under this section...

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

Code of Federal Regulations, 2014 CFR

2014-07-01

... 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... as modified styrene, divinylbenzene polymer (PMN P-07-642) is subject to reporting under this section...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

... 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... as modified styrene, divinylbenzene polymer (PMN P-07-642) is subject to reporting under this section...

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

PubMed

Pleban, Francis T; Oketope, Olutosin; Shrestha, Laxmi

2017-12-01

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.

Biotrickling filter modeling for styrene abatement. Part 2: Simulating a two-phase partitioning bioreactor.

PubMed

San-Valero, Pau; Dorado, Antonio D; Quijano, Guillermo; Álvarez-Hornos, F Javier; Gabaldón, Carmen

2018-01-01

A dynamic model describing styrene abatement was developed for a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The model was built as a coupled set of two different systems of partial differential equations depending on whether an irrigation or a non-irrigation period was simulated. The maximum growth rate was previously calibrated from a conventional BTF treating styrene (Part 1). The model was extended to simulate the TPPB-BTF based on the hypothesis that the main change associated with the non-aqueous phase is the modification of the pollutant properties in the liquid phase. The three phases considered were gas, a water-silicone liquid mixture, and biofilm. The selected calibration parameters were related to the physical properties of styrene: Henry's law constant, diffusivity, and the gas-liquid mass transfer coefficient. A sensitivity analysis revealed that Henry's law constant was the most sensitive parameter. The model was successfully calibrated with a goodness of fit of 0.94. It satisfactorily simulated the performance of the TPPB-BTF at styrene loads ranging from 13 to 77 g C m -3 h -1 and empty bed residence times of 30-15 s with the mass transfer enhanced by a factor of 1.6. The model was validated with data obtained in a TPPB-BTF removing styrene continuously. The experimental outlet emissions associated to oscillating inlet concentrations were satisfactorily predicted by using the calibrated parameters. Model simulations demonstrated the potential improvement of the mass-transfer performance of a conventional BTF degrading styrene by adding silicone oil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Immobilization of Acidithiobacillus ferrooxidans on sulfonated microporous poly(styrene-divinylbenzene) copolymer with granulated activated carbon and its use in bio-oxidation of ferrous iron.

PubMed

Koseoglu-Imer, Derya Yuksel; Keskinler, Bulent

2013-01-01

The immobilization efficiencies of Acidithiobacillus ferrooxidans cells on different immobilization matrices were investigated for biooxidation of ferrous iron (Fe(2+)) to ferric iron (Fe(3+)). Six different matrices were used such as the polyurethane foam (PUF), granular activated carbon (GAC), raw poly(styrene-divinylbenzene) copolymer (rawSDVB), raw poly(styrene-divinylbenzene) copolymer with granular activated carbon (rawSDVB-GAC), sulfonated poly(styrene-divinylbenzene) copolymer (sulfSDVB) and sulfonated poly(styrene-divinylbenzene) copolymer with granular activated carbon (sulfSDVB-GAC). The sulfSDVB-GAC polymer showed the best performance for Fe(2+) biooxidation. It was used at packed-bed bioreactor and the kinetic parameters were obtained. The highest Fe(2+) biooxidation rate (R) was found to be 4.02 g/L h at the true dilution rate (Dt) of 2.47 1/h and hydraulic retention time (τ) of 0.4 h. The sulfSDVB-GAC polymer was used for the first time as immobilization material for A. ferrooxidans for Fe(2+) biooxidation. Copyright © 2012 Elsevier B.V. All rights reserved.

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

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymers of styrene, cyclohexyl... Significant New Uses for Specific Chemical Substances § 721.9492 Polymers of styrene, cyclohexyl methacrylate... generically as polymers of styrene, cyclohexyl methacrylate and substituted methacrylate (PMNs P-97-143/144...

The Structure of Ethylbenzene, Styrene and Phenylacetylene Determined by Total Neutron Scattering

PubMed Central

Szala‐Bilnik, Joanna; Falkowska, Marta; Bowron, Daniel T.

2017-01-01

Abstract Organic solvents such as phenylacetylene, styrene and ethylbenzene are widely used in industrial processes, especially in the production of rubber or thermoplastics. Despite their important applications detailed knowledge about their structure is limited. In this paper the structures of these three aromatic solvents were investigated using neutron diffraction. The results show that many of their structural characteristics are similar, although the structure of phenylacetylene is more ordered and has a smaller solvation sphere than either ethylbenzene or styrene. Two regions within the first coordination sphere, in which the surrounding molecules show different preferable orientations with respect to the central molecule, were found for each liquid. Additionally, the localisation of the aliphatic chains reveals that they tend to favour closer interactions with each other than to the aromatic rings of the adjacent molecules. PMID:28672104

Occupational styrene exposure induces stress-responsive genes involved in cytoprotective and cytotoxic activities.

PubMed

Strafella, Elisabetta; Bracci, Massimo; Staffolani, Sara; Manzella, Nicola; Giantomasi, Daniele; Valentino, Matteo; Amati, Monica; Tomasetti, Marco; Santarelli, Lory

2013-01-01

The aim of this study was to evaluate the expression of a panel of genes involved in toxicology in response to styrene exposure at levels below the occupational standard setting. Workers in a fiber glass boat industry were evaluated for a panel of stress- and toxicity-related genes and associated with biochemical parameters related to hepatic injury. Urinary styrene metabolites (MA+PGA) of subjects and environmental sampling data collected for air at workplace were used to estimate styrene exposure. Expression array analysis revealed massive upregulation of genes encoding stress-responsive proteins (HSPA1L, EGR1, IL-6, IL-1β, TNSF10 and TNFα) in the styrene-exposed group; the levels of cytokines released were further confirmed in serum. The exposed workers were then stratified by styrene exposure levels. EGR1 gene upregulation paralleled the expression and transcriptional protein levels of IL-6, TNSF10 and TNFα in styrene exposed workers, even at low level. The activation of the EGR1 pathway observed at low-styrene exposure was associated with a slight increase of hepatic markers found in highly exposed subjects, even though they were within normal range. The ALT and AST levels were not affected by alcohol consumption, and positively correlated with urinary styrene metabolites as evaluated by multiple regression analysis. The pro-inflammatory cytokines IL-6 and TNFα are the primary mediators of processes involved in the hepatic injury response and regeneration. Here, we show that styrene induced stress responsive genes involved in cytoprotection and cytotoxicity at low-exposure, that proceed to a mild subclinical hepatic toxicity at high-styrene exposure.

Occupational Styrene Exposure Induces Stress-Responsive Genes Involved in Cytoprotective and Cytotoxic Activities

PubMed Central

Strafella, Elisabetta; Bracci, Massimo; Staffolani, Sara; Manzella, Nicola; Giantomasi, Daniele; Valentino, Matteo; Amati, Monica; Tomasetti, Marco; Santarelli, Lory

2013-01-01

Objective The aim of this study was to evaluate the expression of a panel of genes involved in toxicology in response to styrene exposure at levels below the occupational standard setting. Methods Workers in a fiber glass boat industry were evaluated for a panel of stress- and toxicity-related genes and associated with biochemical parameters related to hepatic injury. Urinary styrene metabolites (MA+PGA) of subjects and environmental sampling data collected for air at workplace were used to estimate styrene exposure. Results Expression array analysis revealed massive upregulation of genes encoding stress-responsive proteins (HSPA1L, EGR1, IL-6, IL-1β, TNSF10 and TNFα) in the styrene-exposed group; the levels of cytokines released were further confirmed in serum. The exposed workers were then stratified by styrene exposure levels. EGR1 gene upregulation paralleled the expression and transcriptional protein levels of IL-6, TNSF10 and TNFα in styrene exposed workers, even at low level. The activation of the EGR1 pathway observed at low-styrene exposure was associated with a slight increase of hepatic markers found in highly exposed subjects, even though they were within normal range. The ALT and AST levels were not affected by alcohol consumption, and positively correlated with urinary styrene metabolites as evaluated by multiple regression analysis. Conclusion The pro-inflammatory cytokines IL-6 and TNFα are the primary mediators of processes involved in the hepatic injury response and regeneration. Here, we show that styrene induced stress responsive genes involved in cytoprotection and cytotoxicity at low-exposure, that proceed to a mild subclinical hepatic toxicity at high-styrene exposure. PMID:24086524

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

PubMed

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.

Structure and Mechanism of Styrene Monooxygenase Reductase: New Insight into the FAD–Transfer Reaction†

PubMed Central

Morrison, Eliot; Kantz, Auric; Gassner, George T.; Sazinsky, Matthew H.

2013-01-01

The two–component flavoprotein styrene monooxygenase (SMO) from Pseudomonas putida S12 catalyzes the NADH– and FAD–dependent epoxidation of styrene to styrene oxide. In this study we investigate the mechanism of flavin reduction and transfer from the reductase (SMOB) to epoxidase (NSMOA) component and report our findings in light of the 2.2–Å crystal structure of SMOB. Upon rapidly mixing with NADH, SMOB forms an NADH→FADox charge–transfer intermediate and catalyzes a hydride–transfer reaction from NADH to FAD, with a rate constant of 49.1 ± 1.4 s−1, in a step that is coupled to the rapid dissociation of NAD+. Electrochemical and equilibrium–binding studies indicate that NSMOA binds FADhq ~13–times more tightly than SMOB, which supports a vectoral transfer of FADhq from the reductase to the epoxidase. After binding to NSMOA, FADhq rapidly reacts with molecular oxygen to form a stable C(4a)–hydroperoxide intermediate. The half–life of apoSMOB generated in the FAD–transfer reaction is increased ~21–fold, supporting the model of a protein–protein interaction between apoSMOB and NSMOA with the peroxide intermediate. The mechanisms of FAD–dissociation and transport from SMOB to NSMOA were probed by monitoring the competitive reduction of cytochrome c in the presence and absence of pyridine nucleotides. Based on these studies, we propose a model in which reduced FAD binds to SMOB in equilibrium between an unreactive, sequestered state (S–state) and more reactive, transfer state (T–state). Dissociation of NAD+ after the hydride transfer–reaction transiently populates the T–state, promoting the transfer of FADhq to NSMOA. The binding of pyridine nucleotides to SMOB–FADhq shifts the FADhq–binding equilibrium from the T–state to the S–state. Additionally, the 2.2–Å crystal structure of SMOB–FADox reported in this work is discussed in light of the pyridine nucleotide–gated flavin–transfer and electron�

Preparation of candidate reference materials for the determination of phosphorus containing flame retardants in styrene-based polymers.

PubMed

Roth, Thomas; Urpi Bertran, Raquel; Latza, Andreas; Andörfer-Lang, Katrin; Hügelschäffer, Claudia; Pöhlein, Manfred; Puchta, Ralph; Placht, Christian; Maid, Harald; Bauer, Walter; van Eldik, Rudi

2015-04-01

Candidate reference materials (RM) for the analysis of phosphorus-based flame retardants in styrene-based polymers were prepared using a self-made mini-extruder. Due to legal requirements of the current restriction for the use of certain hazardous substances in electrical and electronic equipment, focus now is placed on phosphorus-based flame retardants instead of the brominated kind. Newly developed analytical methods for the first-mentioned substances also require RMs similar to industrial samples for validation and verification purposes. Hence, the prepared candidate RMs contained resorcinol-bis-(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), triphenyl phosphate and triphenyl phosphine oxide as phosphorus-based flame retardants. Blends of polycarbonate and acrylonitrile-co-butadiene-co-styrene as well as blends of high-impact polystyrene and polyphenylene oxide were chosen as carrier polymers. Homogeneity and thermal stability of the candidate RMs were investigated. Results showed that the candidate RMs were comparable to the available industrial materials. Measurements by ICP/OES, FTIR and NMR confirmed the expected concentrations of the flame retardants and proved that analyte loss and degradation, respectively, was below the uncertainty of measurement during the extrusion process. Thus, the candidate RMs were found to be suitable for laboratory use.

Biodegradation of gas-phase styrene using the fungus Sporothrix variecibatus: impact of pollutant load and transient operation.

PubMed

Rene, Eldon R; Veiga, María C; Kennes, Christian

2010-03-01

Biofiltration of gas-phase styrene was studied using a newly isolated fungus Sporothrix variecibatus, in a perlite biofilter, at inlet concentrations and gas-flow rates ranging from 0.13 to 14 g m(-3) and 0.075 to 0.34 m(3) h(-1), respectively, corresponding to empty bed residence times (EBRT) ranging between 91 and 20s. Styrene loading rates were varied between 50 and 845 g m(-3) h(-1)and a maximum elimination capacity of 336 g m(-3) h(-1) was attained with nearly 65% styrene removal. On the other hand, the critical inlet loads to achieve more than 90% removal were 301, 240 and 92 g m(-3) h(-1) for EBRT of 91, 40, and 20s, respectively. In order to test the stability and shock bearing capacity of the fungal biofilter, short-term tests were conducted by suddenly increasing the gas-phase styrene concentration, while maintaining the gas-flow rate constant. The response, a restoration in the removal performance to previous high values, after subjecting the biofilter to shock loads proves the resilient nature of the attached Sporothrix sp. and its suitability for biofiltration under non-steady state conditions. 2010 Elsevier Ltd. All rights reserved.

The Structure of Ethylbenzene, Styrene and Phenylacetylene Determined by Total Neutron Scattering.

PubMed

Szala-Bilnik, Joanna; Falkowska, Marta; Bowron, Daniel T; Hardacre, Christopher; Youngs, Tristan G A

2017-09-20

Organic solvents such as phenylacetylene, styrene and ethylbenzene are widely used in industrial processes, especially in the production of rubber or thermoplastics. Despite their important applications detailed knowledge about their structure is limited. In this paper the structures of these three aromatic solvents were investigated using neutron diffraction. The results show that many of their structural characteristics are similar, although the structure of phenylacetylene is more ordered and has a smaller solvation sphere than either ethylbenzene or styrene. Two regions within the first coordination sphere, in which the surrounding molecules show different preferable orientations with respect to the central molecule, were found for each liquid. Additionally, the localisation of the aliphatic chains reveals that they tend to favour closer interactions with each other than to the aromatic rings of the adjacent molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphological and physical characterization of poly(styrene-isobutylene-styrene) block copolymers and ionomers thereof

NASA Astrophysics Data System (ADS)

Baugh, Daniel Webster, III

Poly(styrene-isobutylene-styrene) block copolymers made by living cationic polymerization using a difunctional initiator and the sequential monomer addition technique were analyzed using curve-resolution software in conjunction with high-resolution GPC. Fractional precipitation and selective solvent extraction were applied to a representative sample in order to confirm the identity of contaminating species. The latter were found to be low molecular weight polystyrene homopolymer, diblock copolymer, and higher molecular weight segmented block copolymers formed by intermolecular electrophilic aromatic substitution linking reactions occurring late in the polymerization of the styrene outer blocks. Solvent-cast films of poly(styrene-isobutylene-styrene) (PS-PIB-PS) block copolymers and block ionomers were analyzed using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Four block copolymer samples with center block molecular weights of 52,000 g/mol and PS volume fractions (o sbPS) ranging from 0.17 to 0.31 were studied. All samples exhibited hexagonally packed cylinders of PS within the PIB matrix. Cylinder spacing was in the range 32 to 36 nm for most samples, while cylinder diameters varied from 14 to 21 nm. Porod analysis of the scattering data indicated the presence of isolated phase mixing and sharp phase boundaries. PS-PIB-PS block copolymers and ionomers therefrom were analyzed using dynamic mechanical analysis (DMA) and tensile testing. The study encompassed five block copolymer samples with similar PIB center blocks with molecular weights of approx52,000 g/mol and PS weight fractions ranging from 0.127 to 0.337. Ionomers were prepared from two of these materials by lightly sulfonating the PS outer blocks. Sulfonation levels varied from 1.7 to 4.7 mol % and the sodium and potassium neutralized forms were compared to the parent block copolymers. Dynamic mechanical analysis (DMA) of the block copolymer films indicated the existence

Effect of nanoparticle metal composition: mono- and bimetallic gold/copper dendrimer stabilized nanoparticles as solvent-free styrene oxidation catalysts

NASA Astrophysics Data System (ADS)

Blanckenberg, A.; Kotze, G.; Swarts, A. J.; Malgas-Enus, R.

2018-02-01

A range of mono- and bimetallic AumCun nanoparticles (NPs), with varying metal compositions, was prepared by using a third-generation diaminobutane poly(propylene imine) (G3 DAB-PPI) dendrimer, modified with alkyl chains, as a stabilizer. It was found that the length of the peripheral alkyl chain, ( M1 (C15), M2 (C11), and M3 (C5)), had a direct influence on the average nanoparticle size obtained, confirming the importance of the nanoparticle stabilizer during synthesis. The Au NPs showed the highest degree of agglomeration and polydispersity, whereas the Cu NPs were the smallest and most monodisperse of the NPs. The bimetallic NPs sizes were found to vary between those of the monometallic NPs, depending on the metal composition. Interestingly, the bimetallic NPs were found to be the most stable, showing very little variation in size over time, even up to 9 months. The DSNs were evaluated in the catalytic oxidation of styrene, using either H2O2 or TBHP as oxidant. Here, we show that the bimetallic DSNs are indeed the superior catalysts when compared to their monometallic analogues, under the same reaction conditions, since a good compromise between stability and activity can be achieved where the Au provides catalytic activity and the Cu serves as a stabilizer. These AumCun bimetallic DSNs present a less expensive and more stable catalyst with negligible loss of activity, opening the door to green catalysis.

Enantioconvergent biohydrolysis of racemic styrene oxide to R-phenyl-1, 2-ethanediol by a newly isolated filamentous fungus Aspergillus tubingensis TF1.

PubMed

Duarah, Aparajita; Goswami, Amrit; Bora, Tarun C; Talukdar, Madhumita; Gogoi, Binod K

2013-08-01

An effort was made to isolate biocatalysts hydrolyzing epoxides from various ecological niches of northeast India, a biodiversity hot spot zone of the world and screened for epoxide hydrolase activity to convert different racemic epoxides to the corresponding 1, 2-vicinal diols. Screening of a total of 450 microorganisms isolated was carried out using NBP colorimetric assay. One of the strains TF1, after internal transcribed spacer sequence analysis, identified as Aspergillus tubingensis, showed promising enantioconvergent epoxide hydrolase activity. The hydrolysis of unsubstituted styrene oxide (1) occurred to give 97 % ee of R-(-)-1-phenylethane-1, 2-diol (6) with more than 99 % conversion within 45 min incubation. It is shown to be a cheap and practical biocatalyst for one step asymmetric synthesis of chiral R-diol. The other representative substrates (2-5), although underwent hydrolysis with more than 99 % conversion beyond 15 h, exhibited poor enantioselectivity.

Covalent attachment of microbial lipase onto microporous styrene-divinylbenzene copolymer by means of polyglutaraldehyde.

PubMed

Dizge, Nadir; Keskinler, Bülent; Tanriseven, Aziz

2008-10-01

A novel method for immobilization of Thermomyces lanuginosus lipase onto polyglutaraldehyde-activated poly(styrene-divinylbenzene) (STY-DVB), which is a hydrophobic microporous support has been successfully developed. The copolymer was prepared by the polymerization of the continuous phase of a high internal phase emulsion (polyHIPE). The concentrated emulsion consists of a mixture of styrene and divinylbenzene containing a suitable surfactant and an initiator as the continuous phase and water as the dispersed phase. Lipase from T. lanuginosus was immobilized covalently with 85% yield on the internal surface of the hydrophobic microporous poly(styrene-divinylbenzene) copolymer and used as a biocatalyst for the transesterification reaction. The immobilized enzyme has been fully active 30 days in storage and retained the activity during the 15 repeated batch reactions. The properties of free and immobilized lipase were studied. The effects of protein concentration, pH, temperature, and time on the immobilization, activity, and stability of the immobilized lipase were also studied. The newly synthesized microporous poly(styrene-divinylbenzene) copolymer constitutes excellent support for lipase. It given rise to high immobilization yield, retains enzymatic activity for 30 days, stable in structure and allows for the immobilization of large amount of protein (11.4mg/g support). Since immobilization is simple yet effective, the newly immobilized lipase could be used in several application including oil hydrolysis, production of modified oils, biodiesel synthesis, and removal of fatty acids from oils.

EVALUATION OF TRICKLE-BED AIR BIOFILTER PERFORMANCE FOR STYRENE REMOVAL

EPA Science Inventory

A pilot-scale trickle-bed air biofilter (TBAB) was evaluated for the removal of styrene from a waste gas stream. Six-millimeter (6 mm) Celite pellets (R-635) were used as the biological attachment medium. The operating parameters considered in the study included the styrene vol...

Styrene recovery from polystyrene by flash pyrolysis in a conical spouted bed reactor.

PubMed

Artetxe, Maite; Lopez, Gartzen; Amutio, Maider; Barbarias, Itsaso; Arregi, Aitor; Aguado, Roberto; Bilbao, Javier; Olazar, Martin

2015-11-01

Continuous pyrolysis of polystyrene has been studied in a conical spouted bed reactor with the main aim of enhancing styrene monomer recovery. Thermal degradation in a thermogravimetric analyser was conducted as a preliminary study in order to apply this information in the pyrolysis in the conical spouted bed reactor. The effects of temperature and gas flow rate in the conical spouted bed reactor on product yield and composition have been determined in the 450-600°C range by using a spouting velocity from 1.25 to 3.5 times the minimum one. Styrene yield is strongly influenced by both temperature and gas flow rate, with the maximum yield being 70.6 wt% at 500°C and a gas velocity twice the minimum one. Copyright © 2015 Elsevier Ltd. All rights reserved.

FRP MODEL - VERSION 1.0 FOR ESTIMATING STYRENE EMISSIONS FROM FIBER-REINFORCED PLASTICS FABRICATION PROCESSES

EPA Science Inventory

This software estimates styrene emissions from the manufacture of fiber-reinforced plastics/composite (FRP/C) products. In using the model, the user first chooses the appropriate process: gel coating, resin sprayup, hand layup, etc. Choosing a process will cause the 'baseline' in...

Polymerization of styrene with cyclopentadienyl nickel complex/methylaluminoxane

NASA Astrophysics Data System (ADS)

Yu, Dongping; Zhang, Danfeng

2017-09-01

Polystyrene was synthesized by Cp(CH2CH2OCH3)NiCl(PPh3) in the presence of methylaluminoxane (MAO). This complex displayed a very high activity for styrene polymerization up to 107 g.mol-1Nih-1. 76.6% styrene was converted to polystyrene (PS) with an average molecular (Mn) of 1.13×105 at 50 °C in 30 min. The structure of the obtained polymer was characterized by 1H NMR and FT-IR.

POTENTIAL FOR REDUCING STYRENE EXPOSURES FROM COPIED PAPER THROUGH USE OF LOW-EMITTING TONERS

EPA Science Inventory

The paper reports results of tests, conducted using 53-L chambers to determine styrene emission rates from freshly copied paper produced on a single photocopier using two toners manufactured for the copier having different styrene contents. Copied-paper styrene emissions with bot...

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

EPA Science Inventory

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...

Biofiltration of air contaminated by styrene vapors on inorganic filtering media: an experimental study.

PubMed

St-Pierre, Marie-Claude Dion; Avalos Ramirez, Antonio; Heitz, Michèle

2009-05-01

This paper presents a study on the biofiltration of styrene by using two inorganic filtering materials. The effects of styrene inlet load and nitrogen concentration present in the nutrient solution on biofilter performance were studied. The styrene inlet concentration was varied from 65 to 1115 parts per million by volume (ppmv), whereas the contaminated airflow rate was fixed at 1 m3/hr. The nitrogen concentration in nutrient solution was varied from 1 to 4 gN/L. The maximum elimination capacity obtained was 105 g/m3-hr, which corresponded to a removal efficiency of 80% for a styrene inlet load of 130 g/m3-hr. This study shows that the nitrogen content in the nutrient solution affects the removal rate of styrene, with an optimal nitrogen concentration of 3 gN/L. The performance comparison between two different inorganic bed types was undertaken and a comparative study on biofiltration of two aromatic compounds, styrene and toluene, is also presented.

Guidance of neurite outgrowth on aligned electrospun polypyrrole/poly(styrene-beta-isobutylene-beta-styrene) fiber platforms.

PubMed

Liu, Xiao; Chen, Jun; Gilmore, Kerry J; Higgins, Michael J; Liu, Yong; Wallace, Gordon G

2010-09-15

The purpose of this work was to investigate the potential biomedical application of novel aligned electrospun polypyrrole (PPy)/poly(styrene-beta-isobutylene-beta-styrene) (SIBS) fibers. After successfully aligning the electroactive PPy/SIBS fibers based on our modified electrospinning method, we demonstrated that neurite outgrowth from PC12 cells could be highly orientated parallel to the aligned PPy/SIBS fibers. Physical interactions between the nerve cells and PPy/SIBS fibers through filopodia "sensing" were observed using atomic force microscopy. These observations indicate a role of contact guidance as a mechanism for the observed alignment. This work highlights the capacity for electroactive PPy/SIBS fibers to support and guide nerve cell differentiation through topographic cues, which is a highly desirable characteristic in medical implants for neurological applications. (c) 2010 Wiley Periodicals, Inc.

Techno-economic analysis of biocatalytic processes for production of alkene expoxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borole, Abhijeet P

2007-01-01

A techno-economic analysis of two different bioprocesses was conducted, one for the conversion of propylene to propylene oxide (PO) and other for conversion of styrene to styrene expoxide (SO). The first process was a lipase-mediated chemo-enzymatic reaction, whereas the second one was a one-step enzymatic process using chloroperoxidase. The PO produced through the chemo-enzymatic process is a racemic product, whereas the latter process (based on chloroperoxidase) produces an enantio-pure product. The former process thus falls under the category of high-volume commodity chemical (PO); whereas the latter is a low-volume, high-value product (SO).A simulation of the process was conducted using themore » bioprocess engineering software SuperPro Designer v6.0 (Intelligen, Inc., Scotch Plains, NJ) to determine the economic feasibility of the process. The purpose of the exercise was to compare biocatalytic processes with existing chemical processes for production of alkene expoxides. The results show that further improvements are needed in improving biocatalyst stability to make these bioprocesses competitive with chemical processes.« less

Preparation of hydrophilic styrene maleic anhydride copolymer fibers for use in papermaking

DOEpatents

Rave, Terence W.

1979-01-01

Hydrophilic fibers may be prepared by discharging a heated and pressurized dispersion of a styrene-maleic anhydride copolymer into a zone of reduced temperature and pressure, and then modifying the fibers so produced by treatment with an aqueous admixture of selected cationic and anionic water-soluble, nitrogen-containing polymers. Blends of the hydrophilic fibers with wood pulp provide paper products having improved physical properties.

Roles of Ring-Hydroxylating Dioxygenases in Styrene and Benzene Catabolism in Rhodococcus jostii RHA1▿ †

PubMed Central

Patrauchan, Marianna A.; Florizone, Christine; Eapen, Shawn; Gómez-Gil, Leticia; Sethuraman, Bhanu; Fukuda, Masao; Davies, Julian; Mohn, William W.; Eltis, Lindsay D.

2008-01-01

Proteomics and targeted gene disruption were used to investigate the catabolism of benzene, styrene, biphenyl, and ethylbenzene in Rhodococcus jostii RHA1, a well-studied soil bacterium whose potent polychlorinated biphenyl (PCB)-transforming properties are partly due to the presence of the related Bph and Etb pathways. Of 151 identified proteins, 22 Bph/Etb proteins were among the most abundant in biphenyl-, ethylbenzene-, benzene-, and styrene-grown cells. Cells grown on biphenyl, ethylbenzene, or benzene contained both Bph and Etb enzymes and at least two sets of lower Bph pathway enzymes. By contrast, styrene-grown cells contained no Etb enzymes and only one set of lower Bph pathway enzymes. Gene disruption established that biphenyl dioxygenase (BPDO) was essential for growth of RHA1 on benzene or styrene but that ethylbenzene dioxygenase (EBDO) was not required for growth on any of the tested substrates. Moreover, whole-cell assays of the ΔbphAa and etbAa1::cmrA etbAa2::aphII mutants demonstrated that while both dioxygenases preferentially transformed biphenyl, only BPDO transformed styrene. Deletion of pcaL of the β-ketoadipate pathway disrupted growth on benzene but not other substrates. Thus, styrene and benzene are degraded via meta- and ortho-cleavage, respectively. Finally, catalases were more abundant during growth on nonpolar aromatic compounds than on aromatic acids. This suggests that the relaxed specificities of BPDO and EBDO that enable RHA1 to grow on a range of compounds come at the cost of increased uncoupling during the latter's initial transformation. The stress response may augment RHA1's ability to degrade PCBs and other pollutants that induce similar uncoupling. PMID:17965160

Evaluation of the Parameters and Conditions of Process in the Ethylbenzene Dehydrogenation with Application of Permselective Membranes to Enhance Styrene Yield

PubMed Central

Araújo, Paulo Jardel P.; Leite, Manuela Souza; Kakuta Ravagnani, Teresa M.

2016-01-01

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. PMID:27069982

Evaluation of the Parameters and Conditions of Process in the Ethylbenzene Dehydrogenation with Application of Permselective Membranes to Enhance Styrene Yield.

PubMed

Araújo, Paulo Jardel P; Leite, Manuela Souza; Ravagnani, Teresa M Kakuta

2016-01-01

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.

A proton-exchange membrane prepared by the radiation grafting of styrene and silica into polytetrafluoroethylene films

NASA Astrophysics Data System (ADS)

Yu, Hongyan; Shi, Jianheng; Zeng, Xinmiao; Bao, Mao; Zhao, Xinqing

2009-07-01

A polytetrafluoroethylene (PTFE) based organic-inorganic hybrid proton-exchange membrane was prepared from simultaneous radiation grafting of styrene (St) into porous PTFE membrane with the in situ sol-gel reaction of tetraethoxysilane (TEOS) followed by sulfonation in fuming sulfonic acid. The effect of radiation on the sol-gel reaction was studied. The results show that radiation promotes the sol-gel reaction with the help of St at room temperature. Incorporated silica gel helps to produce higher degree of grafting (DOG). SEM analysis was conducted to confirm that the inorganic silicon oxide was introduced to produce hybrid membrane in this work. The proton conductivity of membrane evaluated using electrochemical impedance spectroscopy is much higher (14.3×10 -2 S cm -1) than that of Nafion ® 117 at temperature of 80 °C with acceptable water uptake 51 wt%.

Ferrate(VI) oxidation of polychlorinated diphenyl sulfides: Kinetics, degradation, and oxidized products.

PubMed

Chen, Jing; Xu, Xinxin; Zeng, Xiaolan; Feng, Mingbao; Qu, Ruijuan; Wang, Zunyao; Nesnas, Nasri; Sharma, Virender K

2018-06-13

This paper presents oxidation of polychlorinated diphenyl sulfides (PCDPSs), dioxin-like compounds, by ferrate(VI) (Fe VI O 4 2- , Fe(VI)). Kinetics of the reactions of Fe(VI) with seventeen PCDPSs, differ in number and positions of chlorine atoms (from 2 to 7), were investigated at pH 8.0. The second-order rate constants (k, M -1 s -1 ) of the reactions varied with the numbers and positions of chlorine atoms and appeared to be related with standard Gibbs free energy of formation (Δ f G 0 ) of PCDPSs. Degradation experiments in the presence of ions and humic acid demonstrated complete removal of PeCDPS by Fe(VI) in minutes. Pathways of the reaction were investigated by identifying oxidized products (OPs) of the reaction between Fe(VI) and 2,2',3',4,5-pentachlorodiphenyl sulfide (PeCDPS) at pH 8.0. Pathways of oxidation involved major pathway of attack on sulfur(II) by Fe(VI) in steps to yield sulfoxide type products, and subsequent breakage of C-S bond with the formation of sulfonic acid-containing trichloro compound. Minor pathways were hydroxylation of benzene ring and substitution of chlorine atom with hydroxyl group. Estimation of toxicity of OPs of the oxidation of PeCDPS by Fe(VI) suggested the decreased toxicity from the parent contaminant. Copyright © 2018. Published by Elsevier Ltd.

Ultrasonic degradation of butadiene, styrene and their copolymers.

PubMed

Sathiskumar, P S; Madras, Giridhar

2012-05-01

Ultrasonic degradation of commercially important polymers, styrene-butadiene (SBR) rubber, acrylonitrile-butadiene (NBR) rubber, styrene-acrylonitrile (SAN), polybutadiene rubber and polystyrene were investigated. The molecular weight distributions were measured using gel permeation chromatography (GPC). A model based on continuous distribution kinetics approach was used to study the time evolution of molecular weight distribution for these polymers during degradation. The effect of solvent properties and ultrasound intensity on the degradation of SBR rubber was investigated using different pure solvents and mixed solvents of varying volatility and different ultrasonic intensities. Copyright © 2011 Elsevier B.V. All rights reserved.

Biomonitoring for Exposure Assessment to Styrene in the Fibreglass Reinforced Plastic Industry: Determinants and Interferents.

PubMed

Bonanni, Rossana Claudia; Gatto, Maria Pia; Paci, Enrico; Gordiani, Andrea; Gherardi, Monica; Tranfo, Giovanna

2015-10-01

Fifty-eight workers exposed to styrene were monitored in four fibreglass reinforced plastic industries of Central Italy. The aim of the study was to explore the factors that can influence the levels of styrene exposure biomarkers of the workers and the aspects that might interfere with the exposure assessment measures, such as the co-exposure to acetone. Personal monitoring of professional exposure to airborne styrene and acetone was carried out by Radiello samplers and GC/MS analysis. Biological monitoring was performed by the determination of urinary metabolites, mandelic (MA), and phenylglyoxylic (PGA) acids with HPLC/MS/MS and unmetabolized styrene in saliva and venous blood by HS/GC/MS. The median values of the four sites ranged between 24.1 to 94.0mg m(-3) and 7.3 to 331.1mg g(-1) creatinine for airborne styrene and MA + PGA, respectively. A good linear correlation was found between styrene in air and its urinary metabolites (r = 0.854). The median value for airborne styrene was found to exceed the (Threshold Limit Value - Time Weighted Average) of 85 mg m(-3) in one site for all the workers and in two if only moulders are considered. The multiple linear regression model showed that the determinants of urinary MA + PGA excretion were the type of process, workers' tasks, level of acetone co-exposure, and the use of respiratory protection devices. Data show that the simultaneous exposure to acetone modify the styrene metabolism with a reduction in the levels of (MA + PGA) excreted. A significant linear log-correlation was found between salivary levels of styrene and blood concentration (r = 0.746) sampled at the same t x time. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Perinatal Toxicity and Carcinogenicity Studies of Styrene –Acrylonitrile Trimer, A Ground Water Contaminant

PubMed Central

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

Characterization of a Poly(styrene-block-methylacrylate-random-octadecylacrylate-block-styrene) Shape Memory ABA Triblock Copolymer

NASA Astrophysics Data System (ADS)

Fei, Pengzhan; Cavicchi, Kevin

2011-03-01

A new ABA triblock copolymer of poly(styrene-block- methylacrylate-random-octadecylacrylate-block-styrene) (PS-b- PMA-r-PODA-b-PS) was synthesized by reversible addition fragmentation chain transfer polymerization. The triblock copolymer can generate a three-dimensional, physically crosslinked network by self-assembly, where the glassy PS domains physically crosslink the midblock chains. The side chain crystallization of the polyoctadecylacrylare (PODA) side chain generates a second reversible network enabling shape memory properties. Shape memory tests by uniaxial deformation and recovery of molded dog-bone shape samples demonstrate that shape fixities above 96% and shape recoveries above 98% were obtained for extensional strains up to 300%. An outstanding advantage of this shape memory material is that it can be very easily shaped and remolded by elevating the temperature to 140circ; C, and after remolding the initial shape memory properties are totally recovered by eliminating the defects introduced by the previous deformation cycling.

Oxidative stability of fermented meat products.

PubMed

Wójciak, Karolina M; Dolatowski, Zbigniew J

2012-04-02

Meat and meat products, which form a major part of our diet, are very susceptible to quality changes resulting from oxidative processes. Quality of fermented food products depends on the course of various physicochemical and biochemical processes. Oxidation of meat components in raw ripening products may be the result of enzymatic changes occurring as a result of activity of enzymes originating in tissues and microorganisms, as well as lipid peroxidation by free radicals. Primary and secondary products of lipid oxidation are extremely reactive and react with other components of meat, changing their physical and chemical properties. Oxidised proteins take on a yellowish, red through brown hue. Products of lipid and protein degradation create a specific flavour and aroma ; furthermore, toxic substances (such as biogenic amines or new substances) are formed as a result of interactions between meat components, e.g. protein-lipid or protein-protein combinations, as well as transverse bonds in protein structures. Oxidation of meat components in raw ripening products is a particularly difficult process. On the one hand it is essential, since the enzymatic and non-enzymatic lipid oxidation creates flavour and aroma compounds characteristic for ripening products; on the other hand excessive amounts or transformations of those compounds may cause the fermented meat product to become a risk to health.

Super-enhanced particle nucleation in styrene emulsion polymerization in the presence of sodium styrene sulfonate.

PubMed

Farias-Cepeda, Lorena; Herrera-Ordonez, Jorge; Hernandez-Martinez, Angel R; Estevez, Miriam; Rosales-Marines, Lucero

2017-08-15

The styrene (St) emulsion polymerization using Aerosol MA80 as surfactant and in the presence of sodium styrene sulfonate (NaSS) was studied. The effect of NaSS content was assessed using MA80 concentrations below and at the critical micellar concentration. It was found that at the higher NaSS and MA80 contents, the number of particles (N) reaches a maximum of the order of 10 17 particles/cm 3 water, a huge value that has never been reported. In this work an explanation for this super-enhanced particle nucleation phenomenon is proposed. Such hypothesis is based on the role of St-NaSS oligomers formed in the aqueous phase and their synergy with MA80 molecules to provide colloidal stability to the system. The proposal seems to be consistent with the experimental data obtained for the evolution of monomer conversion, N, particles size distribution and the wideness of this latter as well as with a theoretical estimation of the N. Copyright © 2017 Elsevier Inc. All rights reserved.

Review: DNA oxidation, its consequences and efficacy of GC-MS and SPME-GC-MS for In Vitro quantification of DNA oxidative products

NASA Astrophysics Data System (ADS)

Singh, Himansha; Udawat, Abhishek; Franklin, Tony; Sarathi, Sai Partha

2012-10-01

DNA oxidation could be one of the main factors contributing to DNA damage, eventually leading to carcinogenesis, mutations or non-carcinogenic diseases such as Parkinsonís and Alzheimerís. Only recently has the focus turned towards identifying oxidative products of DNA and their consequences. Metabolism activities in vitro produce reactive radicals, which can break DNA strands to cause lesions. These lesions could also act as biomarkers for diagnostic purposes. This review provides an insight of the DNA oxidation mechanism, its harmful consequences and the advantages/disadvantages of available techniques to quantify such DNA oxidative products, focussing mainly on the use GC-MS along with derivatization reaction. In addition, the review also discusses the use of Solid Phase Micro Extraction (SPME) before conducting GC-MS as a potential assay to overcome the discrepancies involved in using GC-MS alone for the identification of DNA oxidative products.

The Role of Oxidative Stress in Parkinson’s Disease

PubMed Central

Dias, Vera; Junn, Eunsung; Mouradian, M. Maral

2014-01-01

Oxidative stress plays an important role in the degeneration of dopaminergic neurons in Parkinson’s disease (PD). Disruptions in the physiologic maintenance of the redox potential in neurons interfere with several biological processes, ultimately leading to cell death. Evidence has been developed for oxidative and nitrative damage to key cellular components in the PD substantia nigra. A number of sources and mechanisms for the generation of reactive oxygen species (ROS) are recognized including the metabolism of dopamine itself, mitochondrial dysfunction, iron, neuroinflammatory cells, calcium, and aging. PD causing gene products including DJ-1, PINK1, parkin, alpha-synuclein and LRRK2 also impact in complex ways mitochondrial function leading to exacerbation of ROS generation and susceptibility to oxidative stress. Additionally, cellular homeostatic processes including the ubiquitin-proteasome system and mitophagy are impacted by oxidative stress. It is apparent that the interplay between these various mechanisms contributes to neurodegeneration in PD as a feed forward scenario where primary insults lead to oxidative stress, which damages key cellular pathogenetic proteins that in turn cause more ROS production. Animal models of PD have yielded some insights into the molecular pathways of neuronal degeneration and highlighted previously unknown mechanisms by which oxidative stress contributes to PD. However, therapeutic attempts to target the general state of oxidative stress in clinical trials have failed to demonstrate an impact on disease progression. Recent knowledge gained about the specific mechanisms related to PD gene products that modulate ROS production and the response of neurons to stress may provide targeted new approaches towards neuroprotection. PMID:24252804

Noble metal-free reduced graphene oxide-ZnxCd₁-xS nanocomposite with enhanced solar photocatalytic H₂-production performance.

PubMed

Zhang, Jun; Yu, Jiaguo; Jaroniec, Mietek; Gong, Jian Ru

2012-09-12

Design and preparation of efficient artificial photosynthetic systems for harvesting solar energy by production of hydrogen from water splitting is of great importance from both theoretical and practical viewpoints. ZnS-based solid solutions have been fully proved to be an efficient visible-light driven photocatalysts, however, the H(2)-production rate observed for these solid solutions is far from exciting and sometimes an expensive Pt cocatalyst is still needed in order to achieve higher quantum efficiency. Here, for the first time we report the high solar photocatalytic H(2)-production activity over the noble metal-free reduced graphene oxide (RGO)-Zn(x)Cd(1-x)S nanocomposite prepared by a facile coprecipitation-hydrothermal reduction strategy. The optimized RGO-Zn(0.8)Cd(0.2)S photocatalyst has a high H(2)-production rate of 1824 μmol h(-1) g(-1) at the RGO content of 0.25 wt % and the apparent quantum efficiency of 23.4% at 420 nm (the energy conversion efficiency is ca. 0.36% at simulated one-sun (AM 1.5G) illumination). The results exhibit significantly improved photocatalytic hydrogen production by 450% compared with that of the pristine Zn(0.8)Cd(0.2)S, and are better than that of the optimized Pt-Zn(0.8)Cd(0.2)S under the same reaction conditions, showing that the RGO-Zn(0.8)Cd(0.2)S nanocomposite represents one of the most highly active metal sulfide photocatalyts in the absence of noble metal cocatalysts. This work creates a green and simple way for using RGO as a support to enhance the photocatalytic H(2)-production activity of Zn(x)Cd(1-x)S, and also demonstrates that RGO is a promising substitute for noble metals in photocatalytic H(2)-production.

AN EMPIRICAL MODEL TO PREDICT STYRENE EMISSIONS FROM FIBER-REINFORCED PLASTICS FABRICATION PROCESSES

EPA Science Inventory

Styrene is a designated hazardous air pollutant, per the 1990 Clean Air Act Amendments. It is also a tropospheric ozone precursor. Fiber-reinforced plastics (FRP) fabrication is the primary source of anthropogenic styrene emissions in the United States. This paper describes an em...

Synthesis and stability of L-tryptophan adsorbed on Ti/MCM-41 as a catalyst for the regioselective aminolysis of styrene oxide

NASA Astrophysics Data System (ADS)

Aghapoor, Kioumars; Amini, Mostafa M.; Jadidi, Khosrow; Mohsenzadeh, Farshid; Darabi, Hossein Reza; Sayahi, Hani; Jalali, Mohammad Reza

2015-11-01

L-tryptophan is adsorbed on the titania surface of Ti/MCM-41 (L-tryp≡Ti/MCM-41) as a novel material via two steps. Ti/MCM-41 was first prepared by grafting TiCl4 on activated MCM-41 mesoporous silica in an anhydrous THF. Subsequent adsorption of L-tryptophan on the surface of grafted Ti sites from an aqueous solution afforded L-tryp≡Ti/MCM-41. Characterization of the material was carried out with thermogravimetric and differential thermogravimetric analyses, powder X-ray diffraction, BET and BJH nitrogen adsorption-desorption methods, Fourier transform infrared, UV-Visible, and energy dispersive X-ray spectroscopes. The results indicate that the adsorption of L-tryptophan on the surface of Ti/MCM-41 occurred. L-tryp≡Ti/MCM-41 was applied successfully as a heterogeneous catalyst for the ring opening of styrene oxide with aniline derivatives and demonstrated high to excellent activity and regioselectivity under microwave irradiation and solvent-free conditions. This thermal-resistant catalyst can be recycled at least five times without appreciable loss of activity, which confirms the strong adsorption of L-tryptophan on Ti/MCM-41.

A health risk benchmark for the neurologic effects of styrene: comparison with NOAEL/LOAEL approach.

PubMed

Rabovsky, J; Fowles, J; Hill, M D; Lewis, D C

2001-02-01

Benchmark dose (BMD) analysis was used to estimate an inhalation benchmark concentration for styrene neurotoxicity. Quantal data on neuropsychologic test results from styrene-exposed workers [Mutti et al. (1984). American Journal of Industrial Medicine, 5, 275-286] were used to quantify neurotoxicity, defined as the percent of tested workers who responded abnormally to > or = 1, > or = 2, or > or = 3 out of a battery of eight tests. Exposure was based on previously published results on mean urinary mandelic- and phenylglyoxylic acid levels in the workers, converted to air styrene levels (15, 44, 74, or 115 ppm). Nonstyrene-exposed workers from the same region served as a control group. Maximum-likelihood estimates (MLEs) and BMDs at 5 and 10% response levels of the exposed population were obtained from log-normal analysis of the quantal data. The highest MLE was 9 ppm (BMD = 4 ppm) styrene and represents abnormal responses to > or = 3 tests by 10% of the exposed population. The most health-protective MLE was 2 ppm styrene (BMD = 0.3 ppm) and represents abnormal responses to > or = 1 test by 5% of the exposed population. A no observed adverse effect level/lowest observed adverse effect level (NOAEL/LOAEL) analysis of the same quantal data showed workers in all styrene exposure groups responded abnormally to > or = 1, > or = 2, or > or = 3 tests, compared to controls, and the LOAEL was 15 ppm. A comparison of the BMD and NOAEL/LOAEL analyses suggests that at air styrene levels below the LOAEL, a segment of the worker population may be adversely affected. The benchmark approach will be useful for styrene noncancer risk assessment purposes by providing a more accurate estimate of potential risk that should, in turn, help to reduce the uncertainty that is a common problem in setting exposure levels.

Control of Sulfidogenesis Through Bio-oxidation of H 2S Coupled to (per)chlorate Reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gregoire, Patrick; Engelbrektson, Anna; Hubbard, Christopher G.

2014-04-04

Here, we investigate H 2S attenuation by dissimilatory perchlorate-reducing bacteria (DPRB). All DPRB tested oxidized H 2S coupled to (per)chlorate reduction without sustaining growth. H 2S was preferentially utilized over organic electron donors resulting in an enriched (34S)-elemental sulfur product. Electron microscopy revealed elemental sulfur production in the cytoplasm and on the cell surface of the DPRB Azospira suillum. We also propose a novel hybrid enzymatic-abiotic mechanism for H 2S oxidation similar to that recently proposed for nitrate-dependent Fe(II) oxidation. The results of this study have implications for the control of biosouring and biocorrosion in a range of industrial environments.

Synthesis and crystal structure of an oxovanadium(IV) complex with a pyrazolone ligand and its use as a heterogeneous catalyst for the oxidation of styrene under mild conditions.

PubMed

Parihar, Sanjay; Pathan, Soyeb; Jadeja, R N; Patel, Anjali; Gupta, Vivek K

2012-01-16

1-Phenyl-3-methyl-4-touloyl-5-pyrazolone (ligand) was synthesized and used to prepare an oxovanadium(IV) complex. The complex was characterized by single-crystal X-ray analysis and various spectroscopic techniques. The single-crystal X-ray analysis of the complex shows that the ligands are coordinated in a syn configuration to each other and create a distorted octahedral environment around the metal ion. A heterogeneous catalyst comprising an oxovanadium(IV) complex and hydrous zirconia was synthesized, characterized by various physicochemical techniques, and successfully used for the solvent-free oxidation of styrene. The influence of the reaction parameters (percent loading, molar ratio of the substrate to H(2)O(2), amount of catalyst, and reaction time) was studied. The catalyst was reused three times without any significant loss in the catalytic activity.

Susceptibility of linear and nonlinear otoacoustic emission components to low-dose styrene exposure.

PubMed

Tognola, G; Chiaramello, E; Sisto, R; Moleti, A

2015-03-01

To investigate potential susceptibility of active cochlear mechanisms to low-level styrene exposure by comparing TEOAEs in workers and controls. Two advanced analysis techniques were applied to detect sub-clinical changes in linear and nonlinear cochlear mechanisms of OAE generation: the wavelet transform to decompose TEOAEs into time-frequency components and extract signal-to-noise ratio and latency of each component, and the bispectrum to detect and extract nonlinear TEOAE contributions as quadratic frequency couplings (QFCs). Two cohorts of workers were examined: subjects exposed exclusively to styrene (N = 9), and subjects exposed to styrene and noise (N = 6). The control group was perfectly matched by age and sex to the exposed group. Exposed subjects showed significantly lowered SNR in TEOAE components at mid-to-high frequencies (above 1.6 kHz) and a shift of QFC distribution towards lower frequencies than controls. No systematic differences were observed in latency. Low-level styrene exposure may have induced a modification of cochlear functionality as concerns linear and nonlinear OAE generation mechanisms. The lack of change in latency seems to suggest that the OAE components, where generation region and latency are tightly coupled, may not have been affected by styrene and noise exposure levels considered here.

H2S protects against methionine-induced oxidative stress in brain endothelial cells.

PubMed

Tyagi, Neetu; Moshal, Karni S; Sen, Utpal; Vacek, Thomas P; Kumar, Munish; Hughes, William M; Kundu, Soumi; Tyagi, Suresh C

2009-01-01

Homocysteine (Hcy) causes cerebrovascular dysfunction by inducing oxidative stress. However, to date, there are no strategies to prevent Hcy-induced oxidative damage. Hcy is an H2S precursor formed from methionine (Met) metabolism. We aimed to investigate whether H2S ameliorated Met-induced oxidative stress in mouse brain endothelial cells (bEnd3). The bEnd3 cells were exposed to Met treatment in the presence or absence of NaHS (donor of H2S). Met-induced cell toxicity increased the levels of free radicals in a concentration-dependent manner. Met increased NADPH-oxidase-4 (NOX-4) expression and mitigated thioredxion-1(Trx-1) expression. Pretreatment of bEnd3 with NaHS (0.05 mM) attenuated the production of free radicals in the presence of Met and protected the cells from oxidative damage. Furthermore, NaHS enhanced inhibitory effects of apocynin, N-acetyl-l-cysteine (NAC), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), Nomega-nitro-l-arginine methyl ester (L-NAME) on ROS production and redox enzymes levels induced by Met. In conclusion, the administration of H2S protected the cells from oxidative stress induced by hyperhomocysteinemia (HHcy), which suggested that NaHS/H2S may have therapeutic potential against Met-induced oxidative stress.

Oxidation of Benzene by Persulfate in the Presence of Fe(III)- and Mn(IV)-Containing Oxides: Stoichiometric Efficiency and Transformation Products.

PubMed

Liu, Haizhou; Bruton, Thomas A; Li, Wei; Buren, Jean Van; Prasse, Carsten; Doyle, Fiona M; Sedlak, David L

2016-01-19

Sulfate radical (SO4(•-)) is a strong, short-lived oxidant that is produced when persulfate (S2O8(2-)) reacts with transition metal oxides during in situ chemical oxidation (ISCO) of contaminated groundwater. Although engineers are aware of the ability of transition metal oxides to activate persulfate, the operation of ISCO remediation systems is hampered by an inadequate understanding of the factors that control SO4(•-) production and the overall efficiency of the process. To address these shortcomings, we assessed the stoichiometric efficiency and products of transition metal-catalyzed persulfate oxidation of benzene with pure iron- and manganese-containing minerals, clays, and aquifer solids. For most metal-containing solids, the stoichiometric efficiency, as determined by the loss of benzene relative to the loss of persulfate, approached the theoretical maximum. Rates of production of SO4(•-) or hydroxyl radical (HO(•)) generated from radical chain reactions were affected by the concentration of benzene, with rates of S2O8(2-) decomposition increasing as the benzene concentration increased. Under conditions selected to minimize the loss of initial transformation products through reaction with radicals, the production of phenol only accounted for 30%-60% of the benzene lost in the presence of O2. The remaining products included a ring-cleavage product that appeared to contain an α,β-unsaturated aldehyde functional group. In the absence of O2, the concentration of the ring-cleavage product increased relative to phenol. The formation of the ring-cleavage product warrants further studies of its toxicity and persistence in the subsurface.

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

Code of Federal Regulations, 2010 CFR

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...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

...), 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...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

...), 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...

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

Code of Federal Regulations, 2014 CFR

2014-07-01

...), 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...

FAD C(4a)-hydroxide stabilized in a naturally fused styrene monooxygenase

PubMed Central

Schlömann, Michael; van Berkel, Willem J.H.; Gassner, George T.

2013-01-01

StyA2B represents a new class of styrene monooxygenases that integrates flavin-reductase and styrene-epoxidase activities into a single polypeptide. This naturally-occurring fusion protein offers new avenues for studying and engineering biotechnologically relevant enantioselective biochemical epoxidation reactions. Stopped-flow kinetic studies of StyA2B reported here identify reaction intermediates similar to those reported for the separate reductase and epoxidase components of related two-component systems. Our studies identify substrate epoxidation and elimination of water from the FAD C(4a)-hydroxide as rate-limiting steps in the styrene epoxidation reaction. Efforts directed at accelerating these reaction steps are expected to greatly increase catalytic efficiency and the value of StyA2B as biocatalyst. PMID:24157359

Lipid oxidation. Part 2. Oxidation products of olive oil methyl esters.

PubMed

Pokorný, J; Tài, P; Parízková, H; Smidrkalová, E; El-Tarras, M F; Janícek, G

1976-01-01

Olive oil was converted into methyl esters which were autoxidized at 60 degrees C. The composition of oxidized products was determined by the comparison of infrared spectra and NMR spectra of the original and acetylated samples, the sample reduced with potassium iodide and the acetylated reduced sample. Oxidized products were separated by preparative thin layer chromatography on silica gel and characterized by selective detection and by infrared spectrometry of the fractions. The oxidation products consisted of hydroperoxido butyl oleate, substituted hydroperoxides, mono- and disubstituted monomeric derivatives and a small amount of oligomers.

Preparation and dielectric properties of novel composites based on oxidized styrene-butadienestyrene copolymer and polyaniline modified exfoliated graphite nanoplates

NASA Astrophysics Data System (ADS)

Lv, Qun-Chen; Li, Ying; Zhong, Zhi-Kui; Wu, Hui-Jun; He, Fu-An; Lam, Kwok-Ho

2018-05-01

To improve the dielectric performance of high-dielectric-constant conductive filler/polymer composites, polyaniline was deposited on exfoliated graphite nanoplates (xGNPs) by in-situ polymerization method to form polyaniline (PANI) coated xGNPs (xGNPs@PANI) as the conductive filler for the oxidized styrene-butadienestyrene copolymer (SBS-FH) containing both hydroxyl and formyloxy groups. The results of TEM, SEM, FTIR, TGA, Raman spectrum, XPS, and WAXD showed that PANI had been coated onto the surface of xGNPs successfully. The xGNPs@PANI/SBS-FH composites were prepared by a simple solution-blending method and the homogenous distribution of xGNPs@PANI in the SBS-FH matrix was confirmed by SEM. The presence of xGNPs@PANI was found to significantly improve the dielectric properties of resultant composite compared to the unmodified xGNPs. For example, the xGNPs@PANI/SBS-FH composite near percolation threshold filled with 9.38 vol.% xGNPs@PANI showed a dielectric constant of 56.8 and a dielectric loss factor of 0.51 at 1000 Hz, while the corresponding values of xGNPs (1.19 vol.%)/SBS composite were 15.96 and 2.91 at 1000 Hz, respectively. In addition, the incorporation of xGNPs@PANI into SBS-FH could effectively enhance the thermal conductivity of resultant xGNPs@PANI/SBS-FH composite.

Cellular effect of styrene substituted biscoumarin caused cellular apoptosis and cell cycle arrest in human breast cancer cells.

PubMed

Perumalsamy, Haribalan; Sankarapandian, Karuppasamy; Kandaswamy, Narendran; Balusamy, Sri Renukadevi; Periyathambi, Dhaiveegan; Raveendiran, Nanthini

2017-11-01

Coumarins occurs naturally across plant kingdoms exhibits significant pharmacological properties and pharmacokinetic activity. The conventional, therapeutic agents are often associated with poor stability, absorption and increased side effects. Therefore, identification of a drug that has little or no-side effect on humans is consequential. Here, we investigated the antiproliferative activity of styrene substituted biscoumarin against various human breast cancer cell lines, such as MCF-7, (ER-) MDA-MB-231 and (AR+) MDA-MB-453. Styrene substituted biscoumarin induced cell death by apoptosis in MDA-MB-231 cell line was analyzed. Antiproliferative activity of Styrene substituted biscoumarin was performed by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Styrene substituted biscoumarin induced apoptosis was assessed by Hoechst staining, Annexin V-fluorescein isothiocyanate/propidium iodide (Annexin V-FITC/PI) staining and flow cytometric analysis. Migratory and proliferating characteristic of breast cancer cell line MDA-MB-231 was also analyzed by wound healing and colony formation assay. Furthermore, mRNA expression of BAX and BCL-2 were quantified using qRT-PCR and protein expression level analyzed by Western blot. The inhibition concentration (IC 50 ) of styrene substituted biscoumarin was assayed against three breast cancer cell lines. The inhibition concentration (IC 50 ) value of styrene substituted biscoumarin toward MDA-MB-231, MDA-MB-453 and MCF-7 cell lines was 5.63, 7.30 and 10.84μg/ml respectively. Styrene substituted biscoumarin induced apoptosis was detected by Hoechst staining, DAPI/PI analysis and flow-cytometric analysis. The migration and proliferative efficiency of MDA-MB-231 cells were completely arrested upon styrene substituted biscoumarin treatment. Also, mRNA gene expression and protein expression of pro-apoptotic (BAX) and anti-apoptotic (BCL-2) genes were analyzed by qRT-PCR and western blot analysis upon

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

EPA Science Inventory

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...

Carbonyl group containing products from nopinone oxidation

NASA Astrophysics Data System (ADS)

Kahnt, A.; Iinuma, Y.; Heinold, A.; Böge, O.; Herrmann, H.

2010-12-01

Biogenic volatile organic compounds (BVOC) such as isoprene, monoterpenes and sesquiterpenes account for a large fraction of the fluxes of atmospheric non-methane hydrocarbons. Their atmospheric degradation leads to multifunctional oxidation products that can contribute to aerosol growth. In particular, semi-volatile carbonyl compounds that are formed during the early stage of the BVOC oxidation play an important role in the formation of subsequent secondary organic aerosol (SOA) compounds. In this study, a series of aerosol chamber experiments were performed to better understand the OH initiated oxidation of nopinone and subsequent oxidation products in both the gas- and particle-phase. Nopinone is a first generation oxidation product of β-pinene and has been rarely studied for its oxidation products (Calogirou et al., 1999). The gas- and particle-phase products were sampled using a denuder/filter setup. The combination of XAD-4 and 2,4-dinitrophenylhydrazine was applied on the denuder surface to enable in-situ derivatisation of carbonyl compounds. After extraction and sample purification, the derivatised carbonyl compounds were analysed with HPLC/(-)ESI-TOFMS. The data obtained from the denuder sample analysis were compared to the data obtained from the concurrent PTR-MS measurement. The PTR-MS was used in the scan mode during the OH reactions to detect unknown gaseous oxidation products. The selected ion mode was used for some of the experiments to determine the time evolution of certain compounds. The off-line denuder sample analysis enabled us to elucidate the structures of unknown compounds whereas the PTR-MS delivers the time series of oxidation products . The influences of NOx and seed particle acidity on gas- and particle-phase product distributions will be presented. References: A. Calogirou, N.R. Jensen, C.J. Nielsen, D. Kotzias, J. Hjorth, Environmental Science & Technology 33 (1999) 453.

Solvent effect on post-irradiation grafting of styrene onto poly(ethylene-alt-tetrafluoroethylene) (ETFE) films

NASA Astrophysics Data System (ADS)

Napoleão Geraldes, Adriana; Augusto Zen, Heloísa; Ribeiro, Geise; Fernandes Parra, Duclerc; Benévolo Lugão, Ademar

2013-03-01

Radiation-induced grafting of styrene onto ETFE films in different solvent was investigated after simultaneous irradiation (in post-irradiation condition) using a 60Co source. Grafting of styrene followed by sulfonation onto poly(ethylene-alt-tetrafluoroethylene) (ETFE) are currently studied for synthesis of ion exchange membranes. The ETFE films were immersed in styrene/toluene, styrene/methanol and styrene/isopropyl alcohol and irradiated at 20 and 100 kGy doses at room temperature. The post-irradiation time was established at 14 day and the grafting degree was evaluated. The grafted films were sulfonated using chlorosulfonic acid and 1,2-dichloroethane 20:80 (v/v) at room temperature for 5 h. The degree of grafting (DOG) was determined gravimetrically and physical or chemical changes were evaluated by differential scanning calorimeter analysis (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The ion exchange capacity (IEC) values showed the best performance of sulfonation for ETFE membranes grafted in toluene solvent. Surface images of the grafted films by SEM technique have presented a strong effect of the solvents on the films morphology.

Two-Step Electrochemical Intercalation and Oxidation of Graphite for the Mass Production of Graphene Oxide.

PubMed

Cao, Jianyun; He, Pei; Mohammed, Mahdi A; Zhao, Xin; Young, Robert J; Derby, Brian; Kinloch, Ian A; Dryfe, Robert A W

2017-12-06

Conventional chemical oxidation routes for the production of graphene oxide (GO), such as the Hummers' method, suffer from environmental and safety issues due to their use of hazardous and explosive chemicals. These issues are addressed by electrochemical oxidation methods, but such approaches typically have a low yield due to inhomogeneous oxidation. Herein we report a two-step electrochemical intercalation and oxidation approach to produce GO on the large laboratory scale (tens of grams) comprising (1) forming a stage 1 graphite intercalation compound (GIC) in concentrated sulfuric acid and (2) oxidizing and exfoliating the stage 1 GIC in an aqueous solution of 0.1 M ammonium sulfate. This two-step approach leads to GO with a high yield (>70 wt %), good quality (>90%, monolayer), and reasonable oxygen content (17.7 at. %). Moreover, the as-produced GO can be subsequently deeply reduced (3.2 at. % oxygen; C/O ratio 30.2) to yield highly conductive (54 600 S m -1 ) reduced GO. Electrochemical capacitors based on the reduced GO showed an ultrahigh rate capability of up to 10 V s -1 due to this high conductivity.

Bee products prevent agrichemical-induced oxidative damage in fish.

PubMed

Ferreira, Daiane; Rocha, Helio Carlos; Kreutz, Luiz Carlos; Loro, Vania Lucia; Marqueze, Alessandra; Koakoski, Gessi; da Rosa, João Gabriel Santos; Gusso, Darlan; Oliveira, Thiago Acosta; de Abreu, Murilo Sander; Barcellos, Leonardo José Gil

2013-01-01

In southern South America and other parts of the world, aquaculture is an activity that complements agriculture. Small amounts of agrichemicals can reach aquaculture ponds, which results in numerous problems caused by oxidative stress in non-target organisms. Substances that can prevent or reverse agrichemical-induced oxidative damage may be used to combat these effects. This study includes four experiments. In each experiment, 96 mixed-sex, 6-month-old Rhamdia quelen (118±15 g) were distributed into eight experimental groups: a control group that was not exposed to contaminated water, three groups that were exposed to various concentrations of bee products, three groups that were exposed to various concentrations of bee products plus tebuconazole (TEB; Folicur 200 CE™) and a group that was exposed to 0.88 mg L(-1) of TEB alone (corresponding to 16.6% of the 96-h LC50). We show that waterborne bee products, including royal jelly (RJ), honey (H), bee pollen (BP) and propolis (P), reversed the oxidative damage caused by exposure to TEB. These effects were likely caused by the high polyphenol contents of these bee-derived compounds. The most likely mechanism of action for the protective effects of bee products against tissue oxidation and the resultant damage is that the enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) are increased.

Estimation of the percutaneous absorption of styrene in an industrial situation.

PubMed

Limasset, J C; Simon, P; Poirot, P; Subra, I; Grzebyk, M

1999-01-01

This field study was designed to compare the level of styrene absorbed percutaneously with that absorbed by inhalation in a real situation in the fiberglass-reinforced polyester industry. The study protocol consisted of comparisons of the patterns of urinary excretion of styrene metabolites by four groups of workers, all of whom performed the same task at the same time in the same workshop but wore the following different protective equipment: total protection with an insulating suit and mask, respiratory equipment only, percutaneous protection only, and no protection. The urinary excretion level of the group with total protection did not significantly differ from that of the group with respiratory protection only. Precutaneous absorption is not a particularly important pathway for styrene absorption during stratification work in the polyester industry. Completely insulating personal protective equipment provides no greater level of protection than does a respirator at positive pressure alone.

H2S Protects Against Methionine–Induced Oxidative Stress in Brain Endothelial Cells

PubMed Central

Tyagi, Neetu; Moshal, Karni S.; Sen, Utpal; Vacek, Thomas P.; Kumar, Munish; Hughes, William M.; Kundu, Soumi

2009-01-01

Abstract Homocysteine (Hcy) causes cerebrovascular dysfunction by inducing oxidative stress. However, to date, there are no strategies to prevent Hcy-induced oxidative damage. Hcy is an H2S precursor formed from methionine (Met) metabolism. We aimed to investigate whether H2S ameliorated Met-induced oxidative stress in mouse brain endothelial cells (bEnd3). The bEnd3 cells were exposed to Met treatment in the presence or absence of NaHS (donor of H2S). Met-induced cell toxicity increased the levels of free radicals in a concentration-dependent manner. Met increased NADPH-oxidase-4 (NOX-4) expression and mitigated thioredxion-1(Trx-1) expression. Pretreatment of bEnd3 with NaHS (0.05 mM) attenuated the production of free radicals in the presence of Met and protected the cells from oxidative damage. Furthermore, NaHS enhanced inhibitory effects of apocynin, N-acetyl-l-cysteine (NAC), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), Nω-nitro-l-arginine methyl ester (L-NAME) on ROS production and redox enzymes levels induced by Met. In conclusion, the administration of H2S protected the cells from oxidative stress induced by hyperhomocysteinemia (HHcy), which suggested that NaHS/H2S may have therapeutic potential against Met-induced oxidative stress. Antioxid. Redox Signal. 11, 25–33. PMID:18837652

Biofiltration of air contaminated by styrene: Effect of nitrogen supply, gas flow rate, and inlet concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorio, H.; Bibeau, L.; Heitz, M.

2000-05-01

The biofiltration process is a promising technology for the treatment of dilute styrene emissions in air. The efficiency of this process is however strongly dependent upon various operational parameters such as the filter bed characteristics, nutrient supplies, input contaminant concentrations, and gas flow rates. The biofiltration of air containing styrene vapors was therefore investigated, employing a novel biomass filter material, in two identical but separate laboratory scale biofiltration units (units 1 and 2), both biofilters being initially inoculated with a microbial consortium. Each biofilter was irrigated with a nutrient solution supplying nitrogen in one of two forms; i.e., mainly asmore » ammonia for unit 1 and exclusively as nitrate for unit 2. The experimental results have revealed that greater styrene elimination rates are achieved in the biofilter supplied with ammonia as the major nitrogen source in comparison to the lesser elimination performance obtained with the nitrate provided biofilter. However, in achieving the high styrene removal rates in the ammonia supplied biofilter, the excess of biomass accumulates on the filtering pellets and causes progressive clogging of the filter media. Furthermore, the effectiveness of nitrate supply as the sole nitrogen nutrient form, on reducing or controlling the biomass accumulation in the filter media in comparison to ammonia, could not be satisfactorily demonstrated because the two biofilters operated with very different styrene elimination capacities. The monitoring of the carbon dioxide concentration profile through both biofilters revealed that the ratio of carbon dioxide produced to the styrene removed was approximately 3/1, which confirms the complete biodegradation of removed styrene, given that some of the organic carbon consumed is also used for the microbial growth. The effects of the most important design parameters, namely styrene input concentrations and gas flow rates, were investigated for

S-Nitroglutathione, a product of the reaction between peroxynitrite and glutathione that generates nitric oxide.

PubMed

Balazy, M; Kaminski, P M; Mao, K; Tan, J; Wolin, M S

1998-11-27

Peroxynitrite (ONOO-) has been shown in studies on vascular relaxation and guanylate cyclase activation to react with glutathione (GSH), generating an intermediate product that promotes a time-dependent production of nitric oxide (NO). In this study, reactions of ONOO- with GSH produced a new substance, which was characterized by liquid chromatography, ultraviolet spectroscopy, and electrospray tandem mass spectrometry. The mass spectrometric data provided evidence that the product of this reaction was S-nitroglutathione (GSNO2) and that S-nitrosoglutathione (GSNO) was not a detectable product of this reaction. Further evidence was obtained by comparison of the spectral and chromatographic properties with synthetic standards prepared by reaction of GSH with nitrosonium or nitronium borofluorates. Both the synthetic and ONOO-/GSH-derived GSNO2 generated a protonated ion, GSNO2H+, at m/z 353, which was unusually resistant to decomposition under collision activation, and no fragmentation was observed at collision energy of 25 eV. In contrast, an ion at m/z 337 (GSNOH+), generated from the synthetic GSNO, readily fragmented with the abundant loss of NO at 9 eV. Reactions of ONOO- with GSH resulted in the generation of NO, which was detected by the head space/NO-chemiluminescence analyzer method. The generation of NO was inhibited by the presence of glucose and/or CO2 in the buffers employed. Synthetic GSNO2 spontaneously generated NO in a manner that was not significantly altered by glucose or CO2. Thus, ONOO- reacts with GSH to form GSNO2, and GSNO2 decomposes in a manner that generates NO.

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

PubMed

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.

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

PubMed Central

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

Modeling of nitrous oxide production by autotrophic ammonia-oxidizing bacteria with multiple production pathways.

PubMed

Ni, Bing-Jie; Peng, Lai; Law, Yingyu; Guo, Jianhua; Yuan, Zhiguo

2014-04-01

Autotrophic ammonia oxidizing bacteria (AOB) have been recognized as a major contributor to N2O production in wastewater treatment systems. However, so far N2O models have been proposed based on a single N2O production pathway by AOB, and there is still a lack of effective approach for the integration of these models. In this work, an integrated mathematical model that considers multiple production pathways is developed to describe N2O production by AOB. The pathways considered include the nitrifier denitrification pathway (N2O as the final product of AOB denitrification with NO2(-) as the terminal electron acceptor) and the hydroxylamine (NH2OH) pathway (N2O as a byproduct of incomplete oxidation of NH2OH to NO2(-)). In this model, the oxidation and reduction processes are modeled separately, with intracellular electron carriers introduced to link the two types of processes. The model is calibrated and validated using experimental data obtained with two independent nitrifying cultures. The model satisfactorily describes the N2O data from both systems. The model also predicts shifts of the dominating pathway at various dissolved oxygen (DO) and nitrite levels, consistent with previous hypotheses. This unified model is expected to enhance our ability to predict N2O production by AOB in wastewater treatment systems under varying operational conditions.

Semisynthesis and bioactive evaluation of oxidized products from 20(S)-ginsenoside Rg3, Rh2, protopanaxadiol (PPD) and their 20(R)-epimers as cytotoxic agents.

PubMed

Yang, Jie; Li, Xuwen; Sun, Ting; Gao, Yan; Chen, Yanxin; Jin, Yongri; Li, Yang

2016-02-01

A series of oxidized products have been systematically semisynthesized from 20(S)-ginsenoside Rg3, Rh2, 20(S)-protopanaxadiol (PPD) and their 20(R)-epimers and the majority of these products were evaluated for their cytotoxic activity against HeLa cells and HepG2 cells by MTT assay for the first time. Twenty-two products were obtained and elucidated based on comprehensive (1)H NMR, (13)C NMR, two-dimensional (2D) NMR, and mass spectral data and the results reported in previous literature. All the four ocotillol type saponins (20S,24R(δ86, δ85); 20S,24S(δ87, δ88); 20R,24R(δ86, δ86); 20R,24S(δ86, δ87) were obtained. In addition, eight compounds (3, 8, 9, 10, 15, 16, 19 and 22) with the cyclized side chain were firstly identified. Most of the tested compounds possessed cytotoxicity to a certain degree against the two types of cells which implied these oxidized products could play a certain role on anti-cancer functions of the raw materials in vivo. Meanwhile, the results proved that the configurations at C-20 or C-24 and the number of glycosyl at C-3 have important influence on the cytotoxicity. The products 1, 2, 11-17, 20 and 22 should possess great activities and deserved further investigation as potential cytotoxic agents. Copyright © 2015 Elsevier Inc. All rights reserved.

ENGINEERING THE BIOSYNTHESIS OF STYRENE IN YEAST

EPA Science Inventory

The strategy pursued was to insert genes for phenylalanine ammonia lysase (pal) and phenolic acid decarboxylase (pad) into the yeast that would convert phenylalanine to styrene through a cinnamic acid intermediate.

Highly oxidized graphene oxide and methods for production thereof

DOEpatents

Tour, James M.; Kosynkin, Dmitry V.

2016-08-30

A highly oxidized form of graphene oxide and methods for production thereof are described in various embodiments of the present disclosure. In general, the methods include mixing a graphite source with a solution containing at least one oxidant and at least one protecting agent and then oxidizing the graphite source with the at least one oxidant in the presence of the at least one protecting agent to form the graphene oxide. Graphene oxide synthesized by the presently described methods is of a high structural quality that is more oxidized and maintains a higher proportion of aromatic rings and aromatic domains than does graphene oxide prepared in the absence of at least one protecting agent. Methods for reduction of graphene oxide into chemically converted graphene are also disclosed herein. The chemically converted graphene of the present disclosure is significantly more electrically conductive than is chemically converted graphene prepared from other sources of graphene oxide.

Long-term operation of submerged membrane bioreactor (MBR) for the treatment of synthetic wastewater containing styrene as volatile organic compound (VOC): Effect of hydraulic retention time (HRT).

PubMed

Fallah, N; Bonakdarpour, B; Nasernejad, B; Alavi Moghadam, M R

2010-06-15

In this study, the membrane bioreactor (MBR) was utilized to remove styrene from a synthetic wastewater having a chemical oxygen demand (COD) and styrene concentration of 1500 mg/L and 50 mg/L, respectively. At two hydraulic retention times (HRTs) of 24 h and 18 h, the MBR was operated for a period in excess of 100 days. The HRT effects were studied and it was found out that the removal efficiency of COD and styrene for both HRTs was consistently higher than 99%. Unlike conventional activated sludge processes (CASPs), no styrene was detected in the exhaust air, which meant that biodegradation was the major styrene removal mechanism at both HRTs. The transmembrane pressure (TMP) profile during the operation of the MBR showed a fairly low and constant TMP up to day 70, after which, the TMP showed a dramatic rise, as a result of the occurrence of severe membrane fouling. It was thought that an increase in styrene loading rate, when HRT was reduced to 18 h, resulted in the release of extracellular polymeric substance (EPS) from the bacterial cells, which in turn was responsible for the rise in soluble microbial product (SMP) and sludge deflocculation. The severe fouling observed during operation of MBR at HRT of 18 h was attributed to the rise in SMP concentrations and decrease in mean floc size and increase in the proportion of small particles in the activated sludge. Copyright 2010 Elsevier B.V. All rights reserved.

Kinetics and structure-activity relationship of dendritic bridged hindered phenol antioxidants to protect styrene against free radical induced peroxidation

NASA Astrophysics Data System (ADS)

Li, Cui-Qin; Guo, Su-Yue; Wang, Jun; Shi, Wei-Guang; Zhang, Zhi-Qiu; Wang, Peng-Xiang

2017-12-01

A series of dendritic poly(amido-amine) (PAMAM) bridged hindered phenols antioxidants were synthesized. The active antioxidant group (3-(3,5-di- tert-butyl-4-hydroxyphenyl)propionic acid) was attached to two generations of PAMAM dendrimers, and their structure was verified by nuclear magnetic resonance (NMR) and fourier transform infrared spectra (FT-IR). The antioxidant abilities of the dendritic phenols to inhibit the oxidation of styrene were evaluated and the relationships between the length of core, the generation of dendrimers and the antioxidant activities were established. The reaction kinetics of scavenging peroxyl radicals was followed by oxygen consumption. The inhibition time ( t inh) values showed the dendritic phenols had the ability of scavenging peroxyl radicals, and that the antioxidant ability increased with the increasing length of the core and the generation. The kinetic analysis demonstrated that dendritic phenols could slow the rate of styrene peroxidation induced by AIBN, as shown by the number of trapping ROO· ( n), and this role was in accordance with that of the t inh values.

Transparent conducting oxides and production thereof

DOEpatents

Gessert, Timothy A; Yoshida, Yuki; Coutts, Timothy J

2014-05-27

Transparent conducting oxides and production thereof are disclosed. An exemplary method of producing a transparent conducting oxide (TCO) material may comprise: providing a TCO target (110) doped with either a high-permittivity oxide or a low-permittivity oxide in a process chamber (100). The method may also comprise depositing a metal oxide on the target (110) to form a thin film having enhanced optical properties without substantially decreasing electrical quality.

Transparent conducting oxides and production thereof

DOEpatents

Gessert, Timothy A.; Yoshida, Yuki; Coutts, Timothy J.

2014-06-10

Transparent conducting oxides and production thereof are disclosed. An exemplary method of producing a transparent conducting oxide (TCO) material may comprise: providing a TCO target doped with either a high-permittivity oxide or a low-permittivity oxide in a process chamber. The method may also comprise depositing a metal oxide on the target in the process chamber to form a thin film having enhanced optical properties without substantially decreasing electrical quality.

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

Code of Federal Regulations, 2010 CFR

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...

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

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 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...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

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

PubMed

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

POTENTIAL FOR REDUCING INDOOR STYRENE EXPOSURE FROM COPIED PAPER THROUGH USE OF LOW-EMITTING TONERS

EPA Science Inventory

Tests were conducted, using 53-L dynamic chambers, to determine airborne styrene emission rates over time from freshly copied paper. Copies were produced on a single photocopier, using two toners manufactured for this copier but having different styrene contents. The resulting em...

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

PubMed

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.

Unprecedented Selective Oxidation of Styrene Derivatives using a Supported Iron Oxide Nanocatalyst in Aqueous Medium

EPA Science Inventory

Iron oxide nanoparticles supported on mesoporous silica-type materials have been successfully utilized in the aqueous selective oxidation of alkenes under mild conditions using hydrogen peroxide as a green oxidant. Catalysts could be easily recovered after completion of the reac...

Halonium ion-assisted deiodination of styrene-based vicinal iodohydrins followed by rearrangement through phenyl migration.

PubMed

Agrawal, Manoj K; Ghosh, Pushpito K

2009-10-16

Acid activation of bromate/bromide couple at 0-10 degrees C was found to trigger the deiodination of styrene-based vicinal iodohydrins. Violet coloration of the organic layer was ascribed to formation of IBr. Deiodination was followed by phenyl migration and deprotonation leading to formation of phenyl acetone and 2-phenylpropanal in good yields from 1-iodo-2-phenylpropan-2-ol and 2-iodo-1-phenylpropan-1-ol, respectively. Phenyl acetaldehyde--which was obtained in 92% GC yield from styrene iodohydrin--was also presumably formed in analogous manner. NBS and HOCl too were effective for transformation of styrene iodohydrin into phenyl acetaldehyde.

Cancer Incidence in Workers Exposed to Styrene in the Danish-reinforced Plastics Industry, 1968-2012.

PubMed

Christensen, Mette Skovgaard; Hansen, Johnni; Ramlau-Hansen, Cecilia Høst; Toft, Gunnar; Kolstad, Henrik

2017-03-01

Occupational exposure to styrene is widespread and has been suggested to be carcinogenic. The aim of this study was to investigate whether occupational exposure to styrene increases the risk of cancer, in particular lymphohematopoietic cancers. We established a study population of 72,292 workers employed in 443 small and medium-sized companies producing reinforced plastics 1964-2007 by utilizing several national registries, expert assessment, and worker survey data. We identified incident cancer cases from 1968 to 2012 in the national Danish cancer registry and computed standardized incidence rate ratios (SIRs) with 95% confidence intervals (95% CI) based on national rates. Increasing SIRs of Hodgkin lymphoma, myeloid leukemia, and cancer of nasal cavities and sinuses were inconsistently associated with increasing duration of employment, early year of first employment, or styrene exposure probability. No such trends were observed for cancer of the esophagus, pancreas, lung, kidney, or urinary bladder, which have previously been associated with styrene exposure. Lung cancer showed an overall increased risk that decreased by duration of employment. Occupational styrene exposure may be associated with Hodgkin lymphoma, myeloid leukemia, and cancer of nasal cavities and sinuses. Further studies are needed to evaluate if the observed associations are likely to be causal.

Heme oxygenase-1 induction by (S)-enantiomer of YS-51 (YS-51S), a synthetic isoquinoline alkaloid, inhibits nitric oxide production and nuclear factor-kappaB translocation in ROS 17/2.8 cells activated with inflammatory stimulants.

PubMed

Chaea, Han-Jung; Kim, Hyung-Ryong; Kang, Young Jin; Hyun, Kwang Chul; Kim, Hye Jung; Seo, Han Geuk; Lee, Jae Heun; Yun-Choi, Hye Sook; Chang, Ki Churl

2007-12-05

Activation of the inducible nitric oxide synthase (iNOS) pathway contributes to inflammation-induced osteoporosis by suppressing bone formation and causing osteoblast apoptosis. We investigated the mechanism of action by which YS-51S, a synthetic isoquinoline alkaloid, inhibits iNOS expression and nitric oxide (NO) production in ROS 17/28 osteoblast cells activated with the mixture of TNF-alpha, IFN-gamma and LPS (MIX). YS-51S, concentration- and time-dependently, increased heme oxygenase (HO-1) expression. Treatment with YS-51S 1 h prior to MIX significantly reduced MIX-induced NO production and iNOS expression with the IC50 to NO production of 47+/-3.3 microM. Electrophoretic mobility shift assay (EMSA) and western blot analysis showed that YS-51S inhibited MIX-mediated activation and translocation of NF-kappaB to nucleus by suppressing the degradation of its inhibitory protein IkappaBalpha in cytoplasm. YS-51S also reduced NF-kappaB-luciferase activity. In addition, an HO-1 inhibitor ZnPPIX, antagonized the inhibitory effect of YS-51S on iNOS expression and DNA strand break induced by MIX, indicating prevention of NO production by YS-51S is associated with HO-1 activity. Moreover, YS-51S inhibited the oxidation of cytochrome c(2+) by peroxynitrite (PN). Our results indicated that YS-51S may be beneficial in NO-mediated inflammatory conditions such as rheumatoid arthritis by alleviating iNOS expression and NO-mediated cell death of osteoblast with 1) inducing HO-1 expression, 2) interfering the activation of NF-kappaB and 3) quenching of PN.

A biofilter integrated with gas membrane separation unit for the treatment of fluctuating styrene loads.

PubMed

Li, Lin; Lian, Jing; Han, Yunping; Liu, Junxin

2012-05-01

Biofiltration for volatile organic compound control in waste gas streams is best operated at steady contaminant loadings. To provide long-term stable operation of a biofilter under adverse contaminant feeding conditions, an integrated bioreactor system with a gas separation membrane module installed after a biofilter was proposed for styrene treatment. Styrene was treated effectively, with average styrene effluent concentrations maintained at less than 50 mg m(-3) and a total removal efficiency of over 96% achieved when the biofiltration column faced fluctuating loads. The maximum elimination capacity of the integrated bioreactor system was 93.8 g m(-3)h(-1), which was higher than that obtained with the biofiltration column alone. The combination of these two processes (microbial and chemical) led to more efficient elimination of styrene and buffering of the fluctuating loads. The factors on gas membrane separation, microbial characteristics in the integrated bioreactor and membrane fouling were also investigated in this study. Copyright © 2012 Elsevier Ltd. All rights reserved.

Kinetics, Mechanism, and Secondary Organic Aerosol Yield of Aqueous Phase Photo-oxidation of α-Pinene Oxidation Products.

PubMed

Aljawhary, Dana; Zhao, Ran; Lee, Alex K Y; Wang, Chen; Abbatt, Jonathan P D

2016-03-10

Formation of secondary organic aerosol (SOA) involves atmospheric oxidation of volatile organic compounds (VOCs), the majority of which are emitted from biogenic sources. Oxidation can occur not only in the gas-phase but also in atmospheric aqueous phases such as cloudwater and aerosol liquid water. This study explores for the first time the aqueous-phase OH oxidation chemistry of oxidation products of α-pinene, a major biogenic VOC species emitted to the atmosphere. The kinetics, reaction mechanisms, and formation of SOA compounds in the aqueous phase of two model compounds, cis-pinonic acid (PIN) and tricarballylic acid (TCA), were investigated in the laboratory; TCA was used as a surrogate for 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a known α-pinene oxidation product. Aerosol time-of-flight chemical ionization mass spectrometry (Aerosol-ToF-CIMS) was used to follow the kinetics and reaction mechanisms at the molecular level. Room-temperature second-order rate constants of PIN and TCA were determined to be 3.3 (± 0.5) × 10(9) and 3.1 (± 0.2) × 10(8) M(-1) s(-1), respectively, from which were estimated their condensed-phase atmospheric lifetimes. Aerosol-ToF-CIMS detected a large number of products leading to detailed reaction mechanisms for PIN and MBTCA. By monitoring the particle size distribution after drying, the amount of SOA material remaining in the particle phase was determined. An aqueous SOA yield of 40 to 60% was determined for PIN OH oxidation. Although recent laboratory studies have focused primarily on aqueous-phase processing of isoprene-related compounds, we demonstrate that aqueous formation of SOA materials also occurs from monoterpene oxidation products, thus representing an additional source of biogenically driven aerosol formation.

Formaldehyde Production from Isoprene Oxidation Across NOx Regimes

NASA Technical Reports Server (NTRS)

Wolfe, G. M.; Kaiser, J.; Hanisco, T. F.; Keutsch, F. N.; de Gouw, J. A.; Gilman, J. B.; Graus, M.; Hatch, C. D.; Holloway, J.; Horowitz, L. W.;

Exposure to styrene and chronic health effects: mortality and incidence of solid cancers in the Danish reinforced plastics industry.

PubMed Central

Kolstad, H A; Juel, K; Olsen, J; Lynge, E

1995-01-01

OBJECTIVES--To study the occurrence of non-malignant diseases and solid cancers in workers exposed to styrene in the Danish reinforced plastics industry. METHODS--All 36,610 workers of 386 reinforced plastics companies and 14,293 workers not exposed to styrene from similar industries were followed up from 1970 to 1990. This industry is characterised by simple exposure conditions, exposure to high concentrations of styrene, and a high proportion of small companies, and the exposure assessment was based on experts' classification on a company level. The mortality from non-malignant causes and the incidence of solid cancers were compared with the national rates. Poisson models were used for internal comparisons. RESULTS--A total of 3031 deaths and 1134 newly diagnosed cases of solid cancer were reported in the workers in the reinforced plastics industry. In companies where 50% or more of the workers produced reinforced plastics an increased mortality rate ratio (MRR) for degenerative disorders of the nervous system (multiple sclerosis, parkinsonism, and motor neurone disease; MRR 1.8, 16 cases, 95% confidence interval (95% CI) 0.9-3.8) and an increased incidence rate ratio (IRR) for pancreatic cancer (IRR 2.2, 17 cases, 95% CI 1.1-4.5) was found. For both disease categories increased occurrence was also found among long term workers, workers of the 1960s (the period with the highest exposure to styrene), and workers with a latent period of more than 10 years after the start of employment. No other non-malignant diseases or solid cancers showed these patterns. CONCLUSION--The findings have to be interpreted with caution, due to the company based exposure assessment, but the possible association between exposures in the reinforced plastics industry, mainly styrene, and degenerative disorders of the nervous system and pancreatic cancer, deserves attention. PMID:7795754

Polybutadiene and Styrene-Butadiene rubbers for high-dose dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliveira, Lucas N.; Instituto de Pesquisas Energeticas e Nucleares -IPEN, Sao Paulo-SP; Vieira, Silvio L.

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 responsemore » 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)« less

Improved biocompatibility of poly (styrene-b-(ethylene-co-butylene)-b-styrene) elastomer by a surface graft polymerization of hyaluronic acid.

PubMed

Li, Xiaomeng; Luan, Shifang; Shi, Hengchong; Yang, Huawei; Song, Lingjie; Jin, Jing; Yin, Jinghua; Stagnaro, Paola

2013-02-01

Hyaluronic acid (HA) is an important component of extracellular matrix (ECM) in many tissues, providing a hemocompatible and supportive environment for cell growth. In this study, glycidyl methacrylate-hyaluronic acid (GMHA) was first synthesized and verified by proton nuclear magnetic resonance ((1)H NMR) spectroscopy. GMHA was then grafted to the surface of biomedical elastomer poly (styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) via an UV-initiated polymerization, monitored by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The further improvement of biocompatibility of the GMHA-modified SEBS films was assessed by platelet adhesion experiments and in vitro response of murine osteoblastic cell line MC-3T3-E1 with the virgin SEBS surface as the reference. It showed that the surface modification with HA strongly resisted platelet adhesion whereas improved cell-substrate interactions. Copyright © 2012 Elsevier B.V. All rights reserved.

Improving olefin tolerance and production in E. coli using native and evolved AcrB

DOE PAGES

Mingardon, Florence; Clement, Camille; Hirano, Kathleen; ...

2015-01-20

Microorganisms can be engineered for the production of chemicals utilized in the polymer industry. However many such target compounds inhibit microbial growth and might correspondingly limit production levels. Here, we focus on compounds that are precursors to bioplastics, specifically styrene and representative alpha-olefins; 1-hexene, 1-octene, and 1-nonene. We evaluated the role of the Escherichia coli efflux pump, AcrAB-TolC, in enhancing tolerance towards these olefin compounds. AcrAB-TolC is involved in the tolerance towards all four compounds in E. coli. Both styrene and 1-hexene are highly toxic to E. coli. Styrene is a model plastics precursor with an established route for productionmore » in E. coli (McKenna and Nielsen, 2011). Though our data indicates that AcrAB-TolC is important for its optimal production, we observed a strong negative selection against the production of styrene in E. coli. Thus we used 1-hexene as a model compound to implement a directed evolution strategy to further improve the tolerance phenotype towards this alpha-olefin. We focused on optimization of AcrB, the inner membrane domain known to be responsible for substrate binding, and found several mutations (A279T, Q584R, F617L, L822P, F927S, and F1033Y) that resulted in improved tolerance. Several of these mutations could also be combined in a synergistic manner. Our study shows efflux pumps to be an important mechanism in host engineering for olefins, and one that can be further improved using strategies such as directed evolution, to increase tolerance and potentially production.« less

Production and consumption of nitric oxide by three methanotrophic bacteria.

PubMed

Ren, T; Roy, R; Knowles, R

2000-09-01

We studied nitrogen oxide production and consumption by methanotrophs Methylobacter luteus (group I), Methylosinus trichosporium OB3b (group II), and an isolate from a hardwood swamp soil, here identified by 16S ribosomal DNA sequencing as Methylobacter sp. strain T20 (group I). All could consume nitric oxide (nitrogen monoxide, NO), and produce small amounts of nitrous oxide (N(2)O). Only Methylobacter strain T20 produced large amounts of NO (>250 parts per million by volume [ppmv] in the headspace) at specific activities of up to 2.0 x 10(-17) mol of NO cell(-1) day(-1), mostly after a culture became O(2) limited. Production of NO by strain T20 occurred mostly in nitrate-containing medium under anaerobic or nearly anaerobic conditions, was inhibited by chlorate, tungstate, and O(2), and required CH(4). Denitrification (methanol-supported N(2)O production from nitrate in the presence of acetylene) could not be detected and thus did not appear to be involved in the production of NO. Furthermore, cd(1) and Cu nitrite reductases, NO reductase, and N(2)O reductase could not be detected by PCR amplification of the nirS, nirK, norB, and nosZ genes, respectively. M. luteus and M. trichosporium produced some NO in ammonium-containing medium under aerobic conditions, likely as a result of methanotrophic nitrification and chemical decomposition of nitrite. For Methylobacter strain T20, arginine did not stimulate NO production under aerobiosis, suggesting that NO synthase was not involved. We conclude that strain T20 causes assimilatory reduction of nitrate to nitrite, which then decomposes chemically to NO. The production of NO by methanotrophs such as Methylobacter strain T20 could be of ecological significance in habitats near aerobic-anaerobic interfaces where fluctuating O(2) and nitrate availability occur.

Production and Consumption of Nitric Oxide by Three Methanotrophic Bacteria

PubMed Central

Ren, Tie; Roy, Réal; Knowles, Roger

2000-01-01

We studied nitrogen oxide production and consumption by methanotrophs Methylobacter luteus (group I), Methylosinus trichosporium OB3b (group II), and an isolate from a hardwood swamp soil, here identified by 16S ribosomal DNA sequencing as Methylobacter sp. strain T20 (group I). All could consume nitric oxide (nitrogen monoxide, NO), and produce small amounts of nitrous oxide (N2O). Only Methylobacter strain T20 produced large amounts of NO (>250 parts per million by volume [ppmv] in the headspace) at specific activities of up to 2.0 × 10−17 mol of NO cell−1 day−1, mostly after a culture became O2 limited. Production of NO by strain T20 occurred mostly in nitrate-containing medium under anaerobic or nearly anaerobic conditions, was inhibited by chlorate, tungstate, and O2, and required CH4. Denitrification (methanol-supported N2O production from nitrate in the presence of acetylene) could not be detected and thus did not appear to be involved in the production of NO. Furthermore, cd1 and Cu nitrite reductases, NO reductase, and N2O reductase could not be detected by PCR amplification of the nirS, nirK, norB, and nosZ genes, respectively. M. luteus and M. trichosporium produced some NO in ammonium-containing medium under aerobic conditions, likely as a result of methanotrophic nitrification and chemical decomposition of nitrite. For Methylobacter strain T20, arginine did not stimulate NO production under aerobiosis, suggesting that NO synthase was not involved. We conclude that strain T20 causes assimilatory reduction of nitrate to nitrite, which then decomposes chemically to NO. The production of NO by methanotrophs such as Methylobacter strain T20 could be of ecological significance in habitats near aerobic-anaerobic interfaces where fluctuating O2 and nitrate availability occur. PMID:10966405

21 CFR 177.1040 - Acrylonitrile/styrene copoly-mer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acrylonitrile/styrene copoly-mer. 177.1040 Section 177.1040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Internal Standard Method”; “Infrared Spectrophotometric Determination of Polymer Extracted from Barex 210...

21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... components of plastic articles intended for use in contact with food, subject to the provisions of this... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1830 Styrene-methyl methacrylate...

21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... components of plastic articles intended for use in contact with food, subject to the provisions of this... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1830 Styrene-methyl methacrylate...

21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... components of plastic articles intended for use in contact with food, subject to the provisions of this... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1830 Styrene-methyl methacrylate...

21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Styrene-methyl methacrylate copolymers. 177.1830 Section 177.1830 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as...

Initiation precursors and initiators in laser-induced copolymerization of styrene and maleic anhydride in acetone

NASA Technical Reports Server (NTRS)

Miner, Gilda A.; Meador, Willard E.; Chang, C. Ken

1990-01-01

The initiation step of photopolymerized styrene/maleic anhydride copolymer was investigated at 365 nm. UV absorption measurements provide decisive evidence that the styrene/maleic anhydride charge transfer complex is the sole absorbing species; however, key laser experiments suggest intermediate reactions lead to a monoradical initiating species. A mechanism for the photoinitiation step of the copolymer is proposed.

Cancer incidence among boat-building workers exposed to styrene.

PubMed

Ruder, Avima M; Bertke, Stephen J

2017-07-01

A cancer incidence analysis was conducted on The National Institute for Occupational Safety and Health boat-builders cohort exposed to styrene, a possible carcinogen. Standardized incidence ratios (SIR) and standardized rate ratios (SRR) were calculated using national and Washington State rates and a person-years analysis program. Among 3704 workers living in Washington State after 1991, when cancer registry case accrual began, 516 first primary diagnoses occurred through 2007. While overall cancer incidence was significantly reduced [SIR: 0.83 (0.76, 0.90)], internal comparisons suggest an association with exposure comparing high to low exposed person-time [SRR: 1.28 (1.05, 1.55)]. There is evidence of styrene exposure being linked to cancer incidence, which is notable since the cohort has not yet reached the median age of cancer diagnosis (65) in the United States. © 2017 Wiley Periodicals, Inc.

Small Angle Neutron Scattering Studies on Blends of Poly (Styrene-ran-Vinyl Phenol) with Liquid Crystalline Polyurethane

NASA Astrophysics Data System (ADS)

Mehta, Rujul

2005-03-01

Molecular composites, composed of uniformly dispersed rigid-rod liquid crystalline polymer (LCP) molecules in a flexible amorphous polymer matrix, have remained hitherto elusive due to a scarcity of miscible systems containing a LCP and an amorphous polymer. The production of such a blend, with an experimentally accessible miscibility window, has become possible by modifying the architecture of the flexible polymer, so as to induce favorable intermolecular hydrogen bonding. Specifically, liquid crystalline polyurethanes (LCPU) are found to be miscible with a copolymer of styrene and vinyl phenol; with optimum hydrogen bonding between the carbonyl groups of the urethane linkages and the hydroxyl groups present in the styrenic matrix. Availability of a truly miscible molecular composite presents a unique opportunity of studying the confirmation of polymer chains containing rigid-rods that are uniformly dispersed in a flexible coil matrix. A system consisting of the LCPU and the deuterated styrenic copolymer containing 20% vinyl phenol is examined by Small Angle Neutron Scattering at the National Center for Neutron Research at Gaithersburg and Technology, and the Institute of Solid State Research (IFF) at Jülich. Scattering curves for neat dPS-VPh did not fit the Debye-Bueche model; indicating complex structure. A two correlation length Debye-Bueche model was considered to accommodate for this nonlinear behavior. This model utilizes four fitting parameters, including two correlation lengths a1 and a2, corresponding to a Debye-Bueche model and Guinier model.

EVALUATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE STYRENE EMISSIONS FROM OPEN CONTACT MOLDING PROCESSES - VOLUME 2. APPENDICES

EPA Science Inventory

The report gives results of a study to evaluate several pollution prevention techniques that could be used to reduce styrene emissions from open molding processes in the fiberglass-reinforced plastics/composites (FRP/C) and fiberglass boat building industries. Styrene emissions u...

Styrene-terminated polysulfone oligomers as matrix material for graphite reinforced composites: An initial study

NASA Technical Reports Server (NTRS)

Garcia, Dana; Bowles, Kenneth J.; Vannucci, Raymond D.

1987-01-01

Styrene terminated polysulfone oligomers are part of an oligomeric class of compounds with end groups capable of thermal polymerization. These materials can be used as matrices for graphite reinforced composites. The initial evaluation of styrene terminated polysulfone oligomer based composites are summarized in terms of fabrication methods, and mechanical and environmental properties. In addition, a description and evaluation is provided of the NASA/Industry Fellowship Program for Technology Transfer.

Insight into nitrous oxide production processes in the western North Pacific based on a marine ecosystem isotopomer model

NASA Astrophysics Data System (ADS)

Yoshikawa, C.; Sasai, Y.; Wakita, M.; Honda, M. C.; Fujiki, T.; Harada, N.; Makabe, A.; Matsushima, S.; Toyoda, S.; Yoshida, N.; Ogawa, N. O.; Suga, H.; Ohkouchi, N.

2016-02-01

Based on the observed inverse relationship between the dissolved oxygen and N2O concentrations in the ocean, previous models have indirectly predicted marine N2O emissions from the apparent oxygen utilization (AOU), In this study, a marine ecosystem model that incorporates nitrous oxide (N2O) production processes (i.e., ammonium oxidation during nitrification and nitrite reduction during nitrifier denitrification) was newly developed to estimate the sea-air N2O flux and to quantify N2O production processes. Site preference of 15N (SP) in N2O isotopomers (14N15N16O and 15N14N16O) and the average nitrogen isotope ratio (δ15N) were added to the model because they are useful tracers to distinguish between ammonium oxidation and nitrite reduction. This model was applied to two contrasting time series sites, a subarctic station (K2) and a subtropical station (S1) in the western North Pacific. The model was validated with observed nitrogen concentration and nitrogen isotopomer datasets, and successfully simulated the higher N2O concentrations, higher δ15N values, and higher site preference values for N2O at K2 compared with S1. The annual mean N2O emissions were estimated to be 34 mg N m-2 yr-1 at K2 and 2 mg N m-2 yr-1 at S1. Using this model, we conducted three case studies: 1) estimating the ratio of in-situ biological N2O production to nitrate (NO3-) production during nitrification, 2) estimating the ratio of N2O production by ammonium oxidation to that by nitrite reduction, and 3) estimating the ratio of AOA ammonium oxidation to AOB ammonium oxidation. The results of case studies estimated the ratios of in situ biological N2O production to nitrate production during nitrification to be 0.22% at K2 and 0.06% at S1. It is also suggested that N2O was mainly produced via ammonium oxidation at K2 but was produced via both ammonium oxidation and nitrite reduction at S1. It is also revealed that 80% of the ammonium oxidation at K2 was caused by archaea in the subsurface

Preparation and infrared/raman classification of 630 spectroscopically encoded styrene copolymers.

PubMed

Fenniri, Hicham; Chun, Sangki; Terreau, Owen; Bravo-Vasquez, Juan-Pablo

2008-01-01

The barcoded resins (BCRs) were introduced recently as a platform for encoded combinatorial chemistry. One of the main challenges yet to be overcome is the demonstration that a large number of BCRs could be generated and classified with high confidence. Here, we describe the synthesis and classification of 630 polystyrene-based copolymers prepared from the combinatorial association of 15 spectroscopically active styrene monomers. Each of the 630 copolymers displayed a unique vibrational fingerprint (infrared and Raman), which was converted into a spectral vector. To each of the 630 copolymers, a vector of the known (reference) composition was assigned. Unknown (prediction) vectors were decoded using multivariate data analysis. From the inner product of the reference and prediction vectors, a correlation map comparing 396 900 copolymer pairs (630 x 630) was generated. In 100% of the cases, the highest correlation was obtained for polymer pairs in which the reference and prediction vectors correspond to copolymers prepared from identical styrene monomers, thus demonstrating the high reliability of this encoding strategy. We have also established that the spectroscopic barcodes generated from the Raman and infrared spectra are independent of the copolymers' morphology (beaded versus bulk polymers). Besides the demonstration of the generality of the polymer barcoding strategy, the analytical methods developed here could in principle be extended to the investigation of the composition and purity of any other synthetic polymer and biopolymer library, or even scaffold-based combinatorial libraries.

The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters

DTIC Science & Technology

2016-01-04

AFRL-AFOSR-VA-TR-2016-0075 The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters KIT BOWEN JOHNS HOPKINS UNIV BALTIMORE MD...Hydride and Boron Aluminum Hydride Clusters 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1-0324 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) KIT...of both Aluminum Hydride Cluster Anions and Boron Aluminum Hydride Cluster Anions with Oxygen: Anionic Products The anionic products of reactions

Syntheses and Post-Polymerization Modifications of Well-Defined Styrenic Polymers Containing Three-Membered Heterocyclic Functionalities

NASA Astrophysics Data System (ADS)

McLeod, David Charles

Macromolecules that contain electrophilic moieties, such as benzyl halides, activated esters, and epoxides, will readily undergo efficient nucleophilic substitution reactions with a wide variety of compounds under mild conditions, and are therefore ideally suited to act as "universal" precursors to functional materials. Epoxide-containing polymers derived from the radical polymerization of commercially-available glycidyl methacrylate are often employed in this role; however, methacrylic polymers suffer from certain limitations as a result of the incorporated ester groups, which are not stabile in the presence of strong nucleophiles, acids, bases, or esterase enzymes. Styrenic polymers that do not contain labile carbonyl moieties are usually the precursors of choice when high chemical stability is desired in the end product, but the production of functional materials from epoxide-containing styrenic polymers is relatively unexplored. In this dissertation, improved methods were developed for synthesizing 4-vinylphenyloxirane (4VPO) and 4-vinylphenyl glycidyl ether (4VPGE), two of the better-known epoxide-containing styrenic monomers, in high-yield and purity. Well-defined, epoxide-containing styrenic polymers with targeted molecular weights, narrow molecular weight distributions, and controlled architectures (specifically, linear and star-shaped homopolymers, as well as linear block copolymers with styrene) were produced from 4VPO and 4VPGE for the first time using reversible-deactivation radical polymerization techniques, such as low-catalyst-concentration atom transfer radical polymerization (LCC ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization. The robust nature and utility of poly4VPO and poly4VPGE were then demonstrated by the efficient, ring-opening modification of the pendant epoxide groups with a structurally- and functionally-diverse array of alcohols under acidic conditions at ambient temperature. The macromolecular

Alkylation of pyridines at their 4-positions with styrenes plus yttrium reagent or benzyl Grignard reagents.

PubMed

Mizumori, Tomoya; Hata, Takeshi; Urabe, Hirokazu

2015-01-02

A new regioselective alkylation of pyridines at their 4-position was achieved with styrenes in the presence of yttrium trichloride, BuLi, and diisobutylaluminium hydride (DIBAL-H) in THF. Alternatively, similar products were more simply prepared from pyridines and benzyl Grignard reagents. These reactions are not only a useful preparation of 4-substituted pyridines but are also complementary to other relevant reactions usually giving 2-substituted pyridines. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Natural realgar and amorphous AsS oxidation kinetics

NASA Astrophysics Data System (ADS)

Lengke, Maggy F.; Tempel, Regina N.

2003-03-01

The oxidation rates of natural realgar and amorphous synthetic AsS by dissolved oxygen were evaluated using mixed flow reactors at pH 7.2 to 8.8 and dissolved oxygen contents of 5.9 to 16.5 ppm over a temperature range of 25 to 40°C. The ratios of As/S are stoichiometric for all amorphous AsS oxidation experiments except for two experiments conducted at pH ˜8.8. In these experiments, stoichiometric ratios of As/S were only observed in the early stages of AsS (am) oxidation whereas lower As/S ratios were observed during steady state. For realgar oxidation experiments, the As/S ratio is less than the stoichiometric ratio of realgar, ranging between 0.61 and 0.71. This nonstoichiometric release of As and S to solution indicates that realgar oxidation is more selective for S after the rates of oxidation become constant. All measured oxidation rates at 25°C can be described within experimental uncertainties as follows: Table 1

Formaldehyde production from isoprene oxidation across NOx regimes

PubMed Central

Wolfe, G. M.; Kaiser, J.; Hanisco, T. F.; Keutsch, F. N.; de Gouw, J. A.; Gilman, J. B.; Graus, M.; Hatch, C. D.; Holloway, J.; Horowitz, L. W.; Lee, B. H.; Lerner, B. M.; Lopez-Hilifiker, F.; Mao, J.; Marvin, M. R.; Peischl, J.; Pollack, I. B.; Roberts, J. M.; Ryerson, T. B.; Thornton, J. A.; Veres, P. R.; Warneke, C.

2018-01-01

The chemical link between isoprene and formaldehyde (HCHO) is a strong, non-linear function of NOx (= NO + NO2). This relationship is a linchpin for top-down isoprene emission inventory verification from orbital HCHO column observations. It is also a benchmark for overall photochemical mechanism performance with regard to VOC oxidation. Using a comprehensive suite of airborne in situ observations over the Southeast U.S., we quantify HCHO production across the urban-rural spectrum. Analysis of isoprene and its major first-generation oxidation products allows us to define both a “prompt” yield of HCHO (molecules of HCHO produced per molecule of freshly-emitted isoprene) and the background HCHO mixing ratio (from oxidation of longer-lived hydrocarbons). Over the range of observed NOx values (roughly 0.1 – 2 ppbv), the prompt yield increases by a factor of 3 (from 0.3 to 0.9 ppbv ppbv−1), while background HCHO increases by a factor of 2 (from 1.6 to 3.3 ppbv). We apply the same method to evaluate the performance of both a global chemical transport model (AM3) and a measurement-constrained 0-D steady state box model. Both models reproduce the NOx dependence of the prompt HCHO yield, illustrating that models with updated isoprene oxidation mechanisms can adequately capture the link between HCHO and recent isoprene emissions. On the other hand, both models under-estimate background HCHO mixing ratios, suggesting missing HCHO precursors, inadequate representation of later-generation isoprene degradation and/or under-estimated hydroxyl radical concentrations. Detailed process rates from the box model simulation demonstrate a 3-fold increase in HCHO production across the range of observed NOx values, driven by a 100% increase in OH and a 40% increase in branching of organic peroxy radical reactions to produce HCHO. PMID:29619046

Formaldehyde production from isoprene oxidation across NOx regimes.

PubMed

Wolfe, G M; Kaiser, J; Hanisco, T F; Keutsch, F N; de Gouw, J A; Gilman, J B; Graus, M; Hatch, C D; Holloway, J; Horowitz, L W; Lee, B H; Lerner, B M; Lopez-Hilifiker, F; Mao, J; Marvin, M R; Peischl, J; Pollack, I B; Roberts, J M; Ryerson, T B; Thornton, J A; Veres, P R; Warneke, C

2016-01-01

The chemical link between isoprene and formaldehyde (HCHO) is a strong, non-linear function of NO x (= NO + NO 2 ). This relationship is a linchpin for top-down isoprene emission inventory verification from orbital HCHO column observations. It is also a benchmark for overall photochemical mechanism performance with regard to VOC oxidation. Using a comprehensive suite of airborne in situ observations over the Southeast U.S., we quantify HCHO production across the urban-rural spectrum. Analysis of isoprene and its major first-generation oxidation products allows us to define both a "prompt" yield of HCHO (molecules of HCHO produced per molecule of freshly-emitted isoprene) and the background HCHO mixing ratio (from oxidation of longer-lived hydrocarbons). Over the range of observed NO x values (roughly 0.1 - 2 ppbv), the prompt yield increases by a factor of 3 (from 0.3 to 0.9 ppbv ppbv -1 ), while background HCHO increases by a factor of 2 (from 1.6 to 3.3 ppbv). We apply the same method to evaluate the performance of both a global chemical transport model (AM3) and a measurement-constrained 0-D steady state box model. Both models reproduce the NO x dependence of the prompt HCHO yield, illustrating that models with updated isoprene oxidation mechanisms can adequately capture the link between HCHO and recent isoprene emissions. On the other hand, both models under-estimate background HCHO mixing ratios, suggesting missing HCHO precursors, inadequate representation of later-generation isoprene degradation and/or under-estimated hydroxyl radical concentrations. Detailed process rates from the box model simulation demonstrate a 3-fold increase in HCHO production across the range of observed NO x values, driven by a 100% increase in OH and a 40% increase in branching of organic peroxy radical reactions to produce HCHO.

Development of graphene oxide/poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) thin film-based electrochemical surface plasmon resonance immunosensor for detection of human immunoglobulin G

NASA Astrophysics Data System (ADS)

Pothipor, Chammari; Lertvachirapaiboon, Chutiparn; Shinbo, Kazunari; Kato, Keizo; Kaneko, Futao; Ounnunkad, Kontad; Baba, Akira

2018-02-01

An electrochemically synthesized graphene oxide (GO)/poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(styrene sulfonate) (PSS) thin film-based electrochemical surface plasmon resonance (EC-SPR) sensor chip was developed and employed for the detection of human immunoglobulin G (IgG). GO introduced the carboxylic group on the film surface, which also allowed electrochemical control, for the immobilization of the anti-IgG antibody via covalent bonding through amide coupling reaction. The SPR sensitivity of the detection was improved under the control by applying an electrochemical potential, by which the sensitivity was increased by the increment in applied potential. Among the open-circuit and different applied potentials in the range of -1.0 to 0.50 V, the EC-SPR immunosensor at an applied potential of 0.50 V exhibited the highest sensitivity of 6.08 × 10-3 mL µg-1 cm-2 and linearity in the human IgG concentration range of 1.0 to 10 µg mL-1 with a relatively low detection limit of 0.35 µg mL-1. The proposed sensor chip is promising for immunosensing at the physiological level.

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

PubMed

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

EVALUATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE STYRENE EMISIONS FROM OPEN CONTACT MOLDING PROCESSES - VOLUME 1. FINAL REPORT

EPA Science Inventory

The report gives results of a study to evaluate several pollution prevention techniques that could be used to reduce styrene emissions from open molding processes in the fiberglass-reinforced
plastics/composites (FRP/C) and fiberglass boat building industries. Styrene emission...

Monolithic column modified with bifunctional ionic liquid and styrene stationary phases for capillary electrochromatography.

PubMed

Mao, Zhenkun; Chen, Zilin

2017-01-13

A novel monolithic column with ionic liquid and styrene-modified bifunctional group was prepared for capillary electrochromatography (CEC) by in situ copolymerization in a ternary porogenic solvent. Ionic liquid (1-allyl-methylimidazolium chloride, AlMeIm + Cl - ) and styrene served as the bifunctional monomer, while ethylene dimethacrylate (EDMA) was used as the cross-linker. The monomer of AlMeIm + Cl - was introduced as anion-exchange group, while styrene as hydrophobic and aromatic group; the similar conjugated structure in AlMeIm + Cl - and styrene was beneficial for offeing obvious synergistic effect. The bifunctional stationary phase possessed powerful selectivity for the separation of neutral compounds, acidic analytes and phenols. The highest column efficiency was 2.70×10 5 platesm -1 (theoretical plates, N) for toluene. A relatively strong electroosmotic flow (EOF) was obtained in a wide range of pH values from 2.0 to 12.0, which could successfully achieve the rapid separation of the analytes within 10min. The proposed monolithic column was characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). The results indicated that the resultant monolithic column had good permeability and excellent mechanical stability. Good reproducibility was obtained with relative standard deviations (RSDs) of the retention time in the range of 0.24-0.47% and 0.81-2.17% for run-to-run (n=5) and day-to-day (n=5), while 1.09-2.70% and 0.98-1.70% for column-to-column (n=3) and batch-to-batch (n=3), respectively. The combination of AlMeIm + Cl - and styrene was a promising option in the fabrication of the organic polymer monolithic column. Copyright © 2016 Elsevier B.V. All rights reserved.

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

EPA Science Inventory

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...

Hepatic effects of orally administered styrene in rats.

PubMed

Srivastava, S P; Das, M; Mushtaq, M; Chandra, S V; Seth, P K

1982-08-01

Adult male rats receiving styrene by gavage (200 or 400 mg kg-1, 6 days a week) for 100 days exhibited a significant dose-dependent increase in hepatic benzo[a]pyrene hydroxylase and aminopyrine-N-demethylase, a decrease in glutathione-S-transferase and no change in glucose-6-phosphatase. A decrease in the activity of mitochondrial succinic dehydrogenase and beta-glucuronidase was also observed. Activity of acid phosphatase was decreased only at the higher dose level. Levels of serum glutamic oxaloacetic transaminase and glutamic pyruvic transaminase were elevated only at the higher dose level. The absolute and relative weights of the liver of control and treated animals showed no significant difference. Histopathological studies of the liver tissue revealed tiny areas of focal necrosis, consisting of few degenerated hepatocytes and inflammatory cells at the higher dose level only.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stephenson, Casey J.; Hassan Beyzavi, M.; Klet, Rachel C.

Reaction of styrene oxide with sodium cyanoborohydride and a catalytic amount of Hf-NU-1000 yields the anti-Markovnikov product, 2-phenylethanol, with over 98% regioselectivity. On the other hand, propylene oxide is ring opened in a Markovnikov fashion to form 2-propanol with 95% regioselectivity. Both styrene oxide and propylene oxide failed to react with sodium cyanoborohydride without the addition of Hf-NU-1000 indicative of the crucial role of Hf-NU-1000 as a catalyst in this reaction. To the best of our knowledge, this is the first report of the use of a metal-organic framework material as a catalyst for ring-opening of epoxides with hydrides.

TEMPO addition into pre-irradiated fluoropolymers and living-radical graft polymerization of styrene for preparation of polymer electrolyte membranes

NASA Astrophysics Data System (ADS)

Sawada, Shin-ichi; Suzuki, Akihiro; Terai, Takayuki; Maekawa, Yasunari

2010-04-01

We prepared proton exchange membranes (PEMs) by 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-mediated living-radical graft polymerization (LRGP) of styrene into fluoropolymer films and subsequent sulfonation. Poly(vinylidene fluoride) (PVDF) and poly(ethylene- co-tetrafluoroethylene) (ETFE) films were first irradiated and then treated with TEMPO solutions in various solvents. TEMPO addition was confirmed by the test of styrene grafting into TEMPO-treated films at 60 °C, at which the LRGP never proceeds. This test enabled us to differentiate the LRGP from the conventional graft polymerization. In order to gain a deep insight about TEMPO-addition reaction, the TEMPO-penetration behavior into the base polymer films was examined by a permeation experiment and computer simulation. Xylene and dioxane were appropriate solvents for the complete introduction of TEMPO into PVDF and ETFE films, respectively. Then, the LRGP of styrene was performed based on the fully TEMPO-capped films at 125 °C with various solvents. By using an alcoholic solvent, the degree of grafting was enhanced and it reached a maximum of 38%. This grafted film was sulfonated to prepare a PEM showing an ion exchange capacity of 2.2 meq/g and proton conductivity of 1.6×10 -1 S/cm.

Enantioselective oxidative stress and oxidative damage caused by Rac- and S-metolachlor to Scenedesmus obliquus.

PubMed

Liu, Huijun; Xia, YiLu; Cai, Weidan; Zhang, Yina; Zhang, Xiaoqiang; Du, Shaoting

2017-04-01

The rational use and environmental security of chiral pesticides has gained the interest of many researchers. The enantioselective effects of Rac- and S-metolachlor on oxidative stress in Scenedesmus obliquus were determined in this study. Stronger green fluorescence was observed in response to S-metolachlor treatment than to Rac-metolachlor treatment, suggesting that more reactive oxygen species (ROS) were stimulated by S-metolachlor. ROS levels following S-metolachlor treatment were 1.92-, 8.31-, and 1.08-times higher than those observed following Rac-metolachlor treatment at 0.1, 0.2, and 0.3 mg/L, respectively. Superoxide dismutase (SOD) and catalase (CAT) were stimulated with increasing herbicide concentrations, with S-metolachlor exhibiting a greater effect. Oxidative damage in terms of chlorophyll (Chl) content, cellular membrane permeability, and cellular ultrastructures of S. obliquus were investigated. Chla and Chlb contents in algae treated with Rac-metolachlor were 2-6-fold higher than those in algae treated with S-metolachlor at 0.1, 0.2, and 0.3 mg/L. The cellular membrane permeability of algae exposed to 0.3 mg/L Rac- and S-metolachlor was 6.19- and 42.5-times that of the control. Correlation analysis implied that ROS are the major factor responsible for the oxidative damage caused by Rac- and S-metolachlor. Damage to the chloroplasts and cell membrane of S. obliquus, low production of starch granules, and an increased number of vacuoles were observed upon ultrastructural morphology analysis by transmission electron microscope. These results indicate that S-metolachlor has a greater effect on S. obliquus than Rac-metolachlor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Technology for High Pure Aluminum Oxide Production from Aluminum Scrap

NASA Astrophysics Data System (ADS)

Ambaryan, G. N.; Vlaskin, M. S.; Shkolnikov, E. I.; Zhuk, A. Z.

2017-10-01

In this study a simple ecologically benign technology of high purity alumina production is presented. The synthesis process consists of three steps) oxidation of aluminum in water at temperature of 90 °C) calcinations of Al hydroxide in atmosphere at 1100 °C) high temperature vacuum processing of aluminum alpha oxide at 1750 °C. Oxidation of aluminum scrap was carried out under intensive mixing in water with small addition of KOH as a catalyst. It was shown that under implemented experimental conditions alkali was continuously regenerated during oxidation reaction and synergistic effect of low content alkali aqueous solution and intensive mixing worked. The product of oxidation of aluminum scrap is the powder of Al(OH)3. Then it can be preliminary granulated or directly subjected to thermal treatment deleting the impurities from the product (aluminum oxide). It was shown the possibility to produce the high-purity aluminum oxide of 5N grade (99.999 %). Aluminum oxide, synthesized by means of the proposed method, meets the requirements of industrial manufacturers of synthetic sapphire (aluminum oxide monocrystals). Obtained high pure aluminum oxide can be also used for the manufacture of implants, artificial joints, microscalpels, high-purity ceramics and other refractory shapes for manufacture of ultra-pure products.

Characterization of oxidation products of TNT metabolism in aquatic phytoremediation systems of Myriophyllum aquaticum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhadra, R.; Spanggord, R.J.; Wayment, D.G.

TNT transformation processes in sediment-free, natural, aquatic phytoremediation systems of Myriophyllum aquaticum were investigated with specific interest in oxidation products. Extraction procedures combining liquid-liquid extractions and solid-phase extractions were developed for the isolation of the mostly acidic, oxidized TNT metabolites. Six compounds unique from the reduction products of TNT were isolated and characterized by UV-vis, {sup 1}H, and {sup 13}C NMR spectroscopy, by mass spectroscopy, and by chemical synthesis where feasible. These compounds include 2-amino-4,6-dinitrobenzoic acid, 2,4-dinitro-6-hydroxyl-benzyl alcohol, 2-N-acetoxyamino-4,6-dinitrobenzaldehyde, 2,4-dinitro-6,hydroxytoluene, and two binuclear metabolites unique from the customary azoxytetranitrotoluenes. The monoaryl compounds show clear evidence of oxidative transformations, methyl oxidationmore » and/or aromatic hydroxylation. It is possible that oxidative transformation(s) preceded nitro reduction since studies on exposure of M. aquaticum to either 2-amino-4,6-dinitrotoluene or 4-amino-2,6-dinitrotoluene did not yield any of the oxidation products identified here. The accumulation of oxidation products was significant: 2-amino-4,6-dinitrobenzoic acid, 4.4%; 2,4-dinitro-6-hydroxy-benzyl alcohol, 8.1%; 2-N-acetoxyamino-4,6-dinitrobenzaldehyde, 7.8%; and, 2,4-dinitro-6-hydroxytoluene, 15.6%. The binuclear metabolites accounted for an estimated 5.6%. This study is the first direct evidence for oxidative transformations in aquatic phytoremediation systems.« less

Application of Lignin as Antioxidant in Styrene Butadiene Rubber Composite

NASA Astrophysics Data System (ADS)

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.

Fast and robust method for the determination of microstructure and composition in butadiene, styrene-butadiene, and isoprene rubber by near-infrared spectroscopy.

PubMed

Vilmin, Franck; Dussap, Claude; Coste, Nathalie

2006-06-01

In the tire industry, synthetic styrene-butadiene rubber (SBR), butadiene rubber (BR), and isoprene rubber (IR) elastomers are essential for conferring to the product its properties of grip and rolling resistance. Their physical properties depend on their chemical composition, i. e., their microstructure and styrene content, which must be accurately controlled. This paper describes a fast, robust, and highly reproducible near-infrared analytical method for the quantitative determination of the microstructure and styrene content. The quantitative models are calculated with the help of pure spectral profiles estimated from a partial least squares (PLS) regression, using (13)C nuclear magnetic resonance (NMR) as the reference method. This versatile approach allows the models to be applied over a large range of compositions, from a single BR to an SBR-IR blend. The resulting quantitative predictions are independent of the sample path length. As a consequence, the sample preparation is solvent free and simplified with a very fast (five minutes) hot filming step of a bulk polymer piece. No precise thickness control is required. Thus, the operator effect becomes negligible and the method is easily transferable. The root mean square error of prediction, depending on the rubber composition, is between 0.7% and 1.3%. The reproducibility standard error is less than 0.2% in every case.

Effect of Mesoporous Diatomite Particles on the Kinetics of SR&NI ATRP of Styrene and Butyl Acrylate

NASA Astrophysics Data System (ADS)

Khezri, Khezrollah; Ghasemi, Moosa; Fazli, Yousef

2018-05-01

Mesoporous diatomite particles were employed to prepare different poly(styrene-co-butyl acrylate)/diatomite nanocomposites. Diatomite nanoplatelets were used for in situ copolymerization of styrene and butyl acrylate by SR&NI ATRP to synthesize well-defined poly(styrene-co-butyl acrylate) nanocomposites. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the diatomite nanoplatelets. Evaluation of pore size distribution and morphological studies were also performed by SEM and TEM. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography respectively. Addition of 3 wt% pristine mesoporous diatomite nanoplatelets leads to increase of conversion from 73 to 89%. Molecular weight of poly(styrene-co-butyl acrylate) chains increases from 17,115 to 20,343 g·mol-1 by addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increases from 1.14 to 1.37. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 35.26 to 39.61°C by adding 3 wt% of mesoporous diatomite nanoplatelets.

Superoxide Production by a Manganese-Oxidizing Bacterium Facilitates Iodide Oxidation

PubMed Central

Li, Hsiu-Ping; Daniel, Benjamin; Creeley, Danielle; Grandbois, Russell; Zhang, Saijin; Xu, Chen; Ho, Yi-Fang; Schwehr, Kathy A.; Kaplan, Daniel I.; Santschi, Peter H.; Hansel, Colleen M.

2014-01-01

The release of radioactive iodine (i.e., iodine-129 and iodine-131) from nuclear reprocessing facilities is a potential threat to human health. The fate and transport of iodine are determined primarily by its redox status, but processes that affect iodine oxidation states in the environment are poorly characterized. Given the difficulty in removing electrons from iodide (I−), naturally occurring iodide oxidation processes require strong oxidants, such as Mn oxides or microbial enzymes. In this study, we examine iodide oxidation by a marine bacterium, Roseobacter sp. AzwK-3b, which promotes Mn(II) oxidation by catalyzing the production of extracellular superoxide (O2−). In the absence of Mn2+, Roseobacter sp. AzwK-3b cultures oxidized ∼90% of the provided iodide (10 μM) within 6 days, whereas in the presence of Mn(II), iodide oxidation occurred only after Mn(IV) formation ceased. Iodide oxidation was not observed during incubations in spent medium or with whole cells under anaerobic conditions or following heat treatment (boiling). Furthermore, iodide oxidation was significantly inhibited in the presence of superoxide dismutase and diphenylene iodonium (a general inhibitor of NADH oxidoreductases). In contrast, the addition of exogenous NADH enhanced iodide oxidation. Taken together, the results indicate that iodide oxidation was mediated primarily by extracellular superoxide generated by Roseobacter sp. AzwK-3b and not by the Mn oxides formed by this organism. Considering that extracellular superoxide formation is a widespread phenomenon among marine and terrestrial bacteria, this could represent an important pathway for iodide oxidation in some environments. PMID:24561582

Superoxide production by a manganese-oxidizing bacterium facilitates iodide oxidation.

PubMed

Li, Hsiu-Ping; Daniel, Benjamin; Creeley, Danielle; Grandbois, Russell; Zhang, Saijin; Xu, Chen; Ho, Yi-Fang; Schwehr, Kathy A; Kaplan, Daniel I; Santschi, Peter H; Hansel, Colleen M; Yeager, Chris M

2014-05-01

The release of radioactive iodine (i.e., iodine-129 and iodine-131) from nuclear reprocessing facilities is a potential threat to human health. The fate and transport of iodine are determined primarily by its redox status, but processes that affect iodine oxidation states in the environment are poorly characterized. Given the difficulty in removing electrons from iodide (I(-)), naturally occurring iodide oxidation processes require strong oxidants, such as Mn oxides or microbial enzymes. In this study, we examine iodide oxidation by a marine bacterium, Roseobacter sp. AzwK-3b, which promotes Mn(II) oxidation by catalyzing the production of extracellular superoxide (O2(-)). In the absence of Mn(2+), Roseobacter sp. AzwK-3b cultures oxidized ∼90% of the provided iodide (10 μM) within 6 days, whereas in the presence of Mn(II), iodide oxidation occurred only after Mn(IV) formation ceased. Iodide oxidation was not observed during incubations in spent medium or with whole cells under anaerobic conditions or following heat treatment (boiling). Furthermore, iodide oxidation was significantly inhibited in the presence of superoxide dismutase and diphenylene iodonium (a general inhibitor of NADH oxidoreductases). In contrast, the addition of exogenous NADH enhanced iodide oxidation. Taken together, the results indicate that iodide oxidation was mediated primarily by extracellular superoxide generated by Roseobacter sp. AzwK-3b and not by the Mn oxides formed by this organism. Considering that extracellular superoxide formation is a widespread phenomenon among marine and terrestrial bacteria, this could represent an important pathway for iodide oxidation in some environments.

Effect of oxidation and extent of oxidation on biologically active PACs in asphalt products.

PubMed

Trumbore, David; Osborn, Linda; Blackburn, Gary; Niebo, Ron; Kriech, Anthony; Maxim, L Daniel

2011-10-01

Recent studies have reported divergent results in rodent cancer assays using fume condensates from a variety of asphalt products. This paper presents results of a study investigating the role of oxidation, or extent of oxidation, on these findings. Five straight run asphalts, made from widely used crude oils, were used as inputs to both production scale and laboratory oxidation units and processed to a range of softening points used in common roofing products. For each of the five asphalts studied, the oxidation reaction significantly decreased measures of polycyclic aromatic compounds (PACs) that have been linked, previously and in analyses included in this study, to tumor induction in rodent bioassays. Mutagenicity index determined by the modified Ames assay was reduced between 41% and 50% from the input asphalt to the final oxidized product. A fluorescence method tuned to a subset of PAC compounds that have been associated with carcinogenic behavior in mouse bioassays was reduced between 39% and 71%. The decrease was largest in the first quarter of the oxidation reaction. These findings indicate that oxidation, by itself, was not a likely factor in the tumor induction seen in the previous studies. Rather, other factors such as the conditions of fume generation and crude source (coupled with possible differences in distillation endpoints) were more likely to have determined the outcomes. Analyses of previously published data, presented in this paper, suggest that the modified Ames and fluorescence assays are valuable screening tools for use in future health-related asphalt research.

Membrane protein extraction and purification using styrene-maleic acid (SMA) copolymer: effect of variations in polymer structure.

PubMed

Morrison, Kerrie A; Akram, Aneel; Mathews, Ashlyn; Khan, Zoeya A; Patel, Jaimin H; Zhou, Chumin; Hardy, David J; Moore-Kelly, Charles; Patel, Roshani; Odiba, Victor; Knowles, Tim J; Javed, Masood-Ul-Hassan; Chmel, Nikola P; Dafforn, Timothy R; Rothnie, Alice J

2016-12-01

The use of styrene-maleic acid (SMA) copolymers to extract and purify transmembrane proteins, while retaining their native bilayer environment, overcomes many of the disadvantages associated with conventional detergent-based procedures. This approach has huge potential for the future of membrane protein structural and functional studies. In this investigation, we have systematically tested a range of commercially available SMA polymers, varying in both the ratio of styrene and maleic acid and in total size, for the ability to extract, purify and stabilise transmembrane proteins. Three different membrane proteins (BmrA, LeuT and ZipA), which vary in size and shape, were used. Our results show that several polymers, can be used to extract membrane proteins, comparably to conventional detergents. A styrene:maleic acid ratio of either 2:1 or 3:1, combined with a relatively small average molecular mass (7.5-10 kDa), is optimal for membrane extraction, and this appears to be independent of the protein size, shape or expression system. A subset of polymers were taken forward for purification, functional and stability tests. Following a one-step affinity purification, SMA 2000 was found to be the best choice for yield, purity and function. However, the other polymers offer subtle differences in size and sensitivity to divalent cations that may be useful for a variety of downstream applications. © 2016 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

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

NASA Astrophysics Data System (ADS)

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.

The impact of respiration and oxidative stress response on recombinant α-amylase production by Saccharomyces cerevisiae.

PubMed

Martínez, José L; Meza, Eugenio; Petranovic, Dina; Nielsen, Jens

2016-12-01

Studying protein production is important for fundamental research on cell biology and applied research for biotechnology. Yeast Saccharomyces cerevisiae is an attractive workhorse for production of recombinant proteins as it does not secrete many endogenous proteins and it is therefore easy to purify a secreted product. However, recombinant production at high rates represents a significant metabolic burden for the yeast cells, which results in oxidative stress and ultimately affects the protein production capacity. Here we describe a method to reduce the overall oxidative stress by overexpressing the endogenous HAP1 gene in a S. cerevisiae strain overproducing recombinant α-amylase. We demonstrate how Hap1p can activate a set of oxidative stress response genes and meanwhile contribute to increase the metabolic rate of the yeast strains, therefore mitigating the negative effect of the ROS accumulation associated to protein folding and hence increasing the production capacity during batch fermentations.

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

PubMed

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.

Modulation of DNA repair capacity and mRNA expression levels of XRCC1, hOGG1 and XPC genes in styrene-exposed workers.

PubMed

Hanova, Monika; Stetina, Rudolf; Vodickova, Ludmila; Vaclavikova, Radka; Hlavac, Pavel; Smerhovsky, Zdenek; Naccarati, Alessio; Polakova, Veronika; Soucek, Pavel; Kuricova, Miroslava; Manini, Paola; Kumar, Rajiv; Hemminki, Kari; Vodicka, Pavel

2010-11-01

Decreased levels of single-strand breaks in DNA (SSBs), reflecting DNA damage, have previously been observed with increased styrene exposure in contrast to a dose-dependent increase in the base-excision repair capacity. To clarify further the above aspects, we have investigated the associations between SSBs, micronuclei, DNA repair capacity and mRNA expression in XRCC1, hOGG1 and XPC genes on 71 styrene-exposed and 51 control individuals. Styrene concentrations at workplace and in blood characterized occupational exposure. The workers were divided into low (below 50 mg/m³) and high (above 50 mg/m³)) styrene exposure groups. DNA damage and DNA repair capacity were analyzed in peripheral blood lymphocytes by Comet assay. The mRNA expression levels were determined by qPCR. A significant negative correlation was observed between SSBs and styrene concentration at workplace (R=-0.38, p=0.001); SSBs were also significantly higher in men (p=0.001). The capacity to repair irradiation-induced DNA damage was the highest in the low exposure group (1.34±1.00 SSB/10⁹ Da), followed by high exposure group (0.72±0.81 SSB/10⁹ Da) and controls (0.65±0.82 SSB/10⁹ Da). The mRNA expression levels of XRCC1, hOGG1 and XPC negatively correlated with styrene concentrations in blood and at workplace (p<0.001) and positively with SSBs (p<0.001). Micronuclei were not affected by styrene exposure, but were higher in older persons and in women (p<0.001). In this study, we did not confirm previous findings on an increased DNA repair response to styrene-induced genotoxicity. However, negative correlations of SSBs and mRNA expression levels of XRCC1, hOGG1 and XPC with styrene exposure warrant further highly-targeted study. Copyright © 2010 Elsevier Inc. All rights reserved.

Improving the catalytic activity of magnetic Fe3O4/ZnO-CdO/reduced graphene oxide for ultrasonic degradation of the organic pollutants and the green oxidation of olefins

NASA Astrophysics Data System (ADS)

Mirzazadeh, Hoda; Lashanizadegan, Maryam

2018-05-01

Magnetic Fe3O4/ZnO-CdO/reduced graphene oxide (MFZC/RGO) has been synthesized by simple hydrothermal method. The structure and morphology were investigated by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Diffuse reflectance spectroscopy (DRS), Vibrating sample magnetometer (VSM), Raman and Fourier-transform infrared spectroscopy (FTIR). MFZC/RGO was applied as catalyst in degradation of methylene blue (MB), rhodamin B (RhB) and methylorange (MO) under ultrasonic irradiation. Based on the results, excellent degradation efficiencies of MB, RhB and MO (>99%) were achieved within 10, 20 and 20 min, respectively under oxygen flow. Moreover the catalytic property of MFZC/RGO was investigated in oxidation of styrene, α-methyl styrene, cyclohexene and cyclooctene under oxygen flow. In addition, MFZC/RGO can be easily collected and separated by an external magnet. The catalyst displayed negligible loss in activity and selectivity within several successive runs due to super paramagnetism.

21 CFR 173.70 - Chloromethylated aminated styrene-divinylbenzene resin.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Chloromethylated aminated styrene-divinylbenzene resin. 173.70 Section 173.70 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Polymer...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

Levofloxacin oxidation by ozone and hydroxyl radicals: kinetic study, transformation products and toxicity.

PubMed

Hamdi El Najjar, Nasma; Touffet, Arnaud; Deborde, Marie; Journel, Romain; Leitner, Nathalie Karpel Vel

2013-10-01

This work was carried out to investigate the fate of the antibiotic levofloxacin upon oxidation with ozone and hydroxyl radicals. A kinetic study was conducted at 20 °C for each oxidant. Ozonation experiments were performed using a competitive kinetic method with carbamazepin as competitor. Significant levofloxacin removal was observed during ozonation and a rate constant value of 6.0×10(4) M(-1) s(-1) was obtained at pH 7.2. An H2O2/UV system was used for the formation of hydroxyl radicals HO. The rate constant of HO was determined in the presence of a high H2O2 concentration. The kinetic expressions yielded a [Formula: see text] value of 4.5×10(9) M(-1) s(-1) at pH 6.0 and 5.2×10(9) M(-1) s(-1) at pH 7.2. These results were used to develop a model to predict the efficacy of the ozonation process and pharmaceutical removal was estimated under different ozonation conditions (i.e. oxidant concentrations and contact times). The results showed that levofloxacin was completely degraded by molecular ozone during ozonation of water and that hydroxyl radicals had no effect in real waters conditions. Moreover, LC/MS/MS and toxicity assays using Lumistox test were performed to identify ozonation transformation products. Under these conditions, four transformation products were observed and their chemical structures were proposed. The results showed an increase in toxicity during ozonation, even after degradation of all of the observed transformation products. The formation of other transformation products not identified under our experimental conditions could be responsible for the observed toxicity. These products might be ozone-resistant and more toxic to Vibrio fisheri than levofloxacin. Copyright © 2013 Elsevier Ltd. All rights reserved.

Bacillus sp. PS35 Lipase-Immobilization on Styrene-Divinyl Benzene Resin and Application in Fatty Acid Methyl Ester Synthesis

PubMed Central

Palanisamy, Kanmani; Kuppamuthu, Kumaresan; Jeyaseelan, Aravind

2015-01-01

Background Lipase is an enzyme with immense application potential. Ester synthesis by lipase catalysis in organic media is an area of key industrial relevance. Enzymatic preparations with traits that cater to the needs of this function are hence being intensely researched. Objective The objectives of the study were to immobilize the lipase from Bacillus sp. PS35 by cross-linking and adsorption onto styrene-divinyl benzene (Sty-Dvb) hydrophobic resin and to comparatively characterize the free and immobilized lipase preparations. The work also aimed to apply the immobilized lipase for catalysing the fatty acid methyl ester (FAME) synthesis from palm oil and optimize the process parameters for maximizing the yield. Materials and Methods In this study, the purified lipase from Bacillus sp. PS35 was immobilized by adsorption onto styrene-divinyl benzene hydrophobic resin with gluteraldehyde cross-linking. Results The immobilized enzyme showed better pH and temperature stabilities than the free lipase. Organic solvent stability was also enhanced, with the relative activity in the presence of methanol being shifted from 53% to 81%, thereby facilitating the enzyme’s application in fatty acid methyl ester synthesis. It exhibited remarkable storage stability over a 30-day period and after 20 repetitive uses. Cross-linking also reduced enzyme leakage by 49%. The immobilized lipase was then applied for biodiesel production from palm oil. Methanol and oil molar ratio of 5:1, three step methanol additions, and an incubation temperature of 50°C were established to be the ideal conditions favoring the transesterification reaction, resulting in 97% methyl ester yield. Conclusions These promising results offer scope for further investigation and process scale up, permitting the enzyme’s commercial application in a practically feasible and economically agreeable manner. PMID:28959298

Photocatalytic wastewater purification with simultaneous hydrogen production using MoS2 QD-decorated hierarchical assembly of ZnIn2S4 on reduced graphene oxide photocatalyst.

PubMed

Zhang, Shuqu; Wang, Longlu; Liu, Chengbin; Luo, Jinming; Crittenden, John; Liu, Xia; Cai, Tao; Yuan, Jili; Pei, Yong; Liu, Yutang

2017-09-15

It is attractive to photocatalytically purify wastewater and simultaneously convert solar energy into clean hydrogen energy. However, it is still a challenge owing to the relatively low photocatalytic efficiency of photocatalysts. In this study, we synthesized a molybdenum disulfide (MoS 2 ) quantum dot-decorated 3D nanoarchitecture (MoS 2 QDs) of indium zinc sulfide (ZnIn 2 S 4 ) and reduced grapheme oxide (MoS 2 QDs@ZnIn 2 S 4 @RGO) photocatalyst using a simple solvothermal method. The RGO promotes the electron transfer, and the highly dispersed MoS 2 QDs provides numerous catalytic sites. The photocatalytic purification of rhodamine B (RhB), eosin Y (EY), fulvic acid (FA), methylene blue (MB) and p-nitrophenol (PNP) in simulated wastewaters were further tested. The degradation efficiencies and TOC removal were 91% and 75% for PNP, 92.2% and 72% for FA, 98.5% and 80% for MB, 98.6% and 84% for EY, and 98.8% and 88% for RhB, respectively (C organics  = 20 mg/L, C catalyst  = 1.25 g/L, t = 12 h, I light  = 3.36 × 10 -5  E L -1  s -1 ). Among these tests, the highest hydrogen production was achieved (45 μmol) during RhB degradation. Both experimental and calculational results prove that lower LUMO (lowest unoccupied molecular orbit) level of organic molecules was available for transferring electrons to catalysts, resulting in more efficient hydrogen production. Significantly, the removal efficiencies of natural organic substances in actual river water reached 76.3-98.4%, and COD reduced from 32 to 16 mg/L with 13.8 μmol H 2 production after 12 h. Copyright © 2017 Elsevier Ltd. All rights reserved.

Disposition of styrene-acrylonitrile (SAN) trimer in female rats: single dose intravenous and gavage studies.

PubMed

Gargas, Michael L; Collins, Brad; Fennell, Timothy R; Gaudette, Norman F; Sweeney, Lisa M

2008-04-21

Styrene-acrylonitrile trimer (SAN Trimer), a mixture of six isomers (four isomers of 4-cyano-1,2,3,4-tetrahydro-alpha-methyl-1-naphthaleneacetonitrile [THAN] and two isomers of 4-cyano-1,2,3,4-tetrahydro-1-naphthaleneproprionitrile [THNP]), is a by-product of a specific production process of styrene-acrylonitrile polymer. Disposition studies in female rats were conducted to evaluate the pharmacokinetic behavior of [3H]SAN Trimer following a single intravenous administration (26 mg/kg) to nonpregnant rats; a single gavage administration (nominal doses of 25 mg/kg, 75 mg/kg, or 200 mg/kg in corn oil) to nonpregnant rats; and a single gavage administration (nominal dose of 200 mg/kg in corn oil) to pregnant and lactating rats. SAN Trimer was rapidly eliminated from blood (T1/2 approximately 1h) following a single intravenous dose and following single oral doses (T1/2 approximately 3-4h). SAN Trimer was also rapidly excreted in the urine and feces following single oral doses, while total radioactivity was cleared more slowly. In pregnant rats, the concentrations of both radioactivity and SAN Trimer 2h after dosing were highest in the blood, followed by the placenta, with the lowest levels in the fetus. In lactating rats, the concentrations of both radioactivity and SAN Trimer were higher in milk than in maternal blood. Total radioactivity and SAN Trimer blood concentrations in nonpregnant, pregnant, and lactating rats were both higher in lactating rats compared to nonpregnant and pregnant rats.

New analytical method for the determination of styrene oligomers formed from polystyrene decomposition and its application at the coastlines of the North-West Pacific ocean.

PubMed

Saido, Katsuhiko; Koizumi, Koshiro; Sato, Hideto; Ogawa, Naoto; Kwon, Bum Gun; Chung, Seon-Yong; Kusui, Takashi; Nishimura, Masahiko; Kodera, Yoichi

2014-03-01

The pollution caused by plastic debris is an environmental problem with increasing concern in the oceans. Among the plastic polymers, polystyrene (PS) is one of the most problematic plastics due to the direct public health risk associated with their dispersion, as well as the numerous adverse environmental impacts which arise both directly from the plastics and from their degradation products. Little is known about their potential distribution characteristics throughout the oceans. For the first time, we report here on the regional distribution of styrene monomer (SM), styrene dimers (SD; 2,4-diphenyl-1-butene, SD1; 1,3-diphenyl propane, SD2), and styrene trimer (2,4,6-triphenyl-1-hexene: ST1), as products of PS decomposition determined from samples of sand and seawater from the shorelines of the North-West Pacific ocean. In order to quantitatively determine SM, SD (=SD1+SD2), and ST1, a new analytical method was developed. The detection limit was 3.3 μg L(-1), based on a signal-to-noise ratio of three, which was well-suited to quantify levels of SM, SD, and ST1 in samples. Surprisingly, the concentrations of SM, SD, and ST1 in sand samples from the shorelines were consistently greater than those in seawater samples from the same location. The results of this study suggest that SM, SD, and ST1 can be widely dispersed throughout the North-West Pacific oceans. Copyright © 2013 Elsevier B.V. All rights reserved.

Regio-selectivity of the Oxidative C-S Bond Formation in Ergothioneine and Ovothiol Biosyntheses

PubMed Central

Song, Heng; Leninger, Maureen; Lee, Norman

2014-01-01

Ergothioneine (5) and ovothiol (8) are two novel thiol-containing natural products. Their C-S bonds are formed by oxidative coupling reactions catalyzed by EgtB and OvoA enzymes, respectively. In this work, it was discovered that besides catalyzing the oxidative coupling between histidine and cysteine (1 → 6 conversion), OvoA can also catalyze a direct oxidative coupling between hercynine (2) and cysteine (2 → 4 conversion), which can shorten the ergothioneine biosynthetic pathway by two steps. PMID:24016264

All-solution-processed PbS quantum dot solar modules

NASA Astrophysics Data System (ADS)

Jang, Jihoon; Shim, Hyung Cheoul; Ju, Yeonkyeong; Song, Jung Hoon; An, Hyejin; Yu, Jong-Su; Kwak, Sun-Woo; Lee, Taik-Min; Kim, Inyoung; Jeong, Sohee

2015-05-01

A rapid increase in power conversion efficiencies in colloidal quantum dot (QD) solar cells has been achieved recently with lead sulphide (PbS) QDs by adapting a heterojunction architecture, which consists of small-area devices associated with a vacuum-deposited buffer layer with metal electrodes. The preparation of QD solar modules by low-cost solution processes is required to further increase the power-to-cost ratio. Herein we demonstrate all-solution-processed flexible PbS QD solar modules with a layer-by-layer architecture comprising polyethylene terephthalate (PET) substrate/indium tin oxide (ITO)/titanium oxide (TiO2)/PbS QD/poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag, with an active area of up to 30 cm2, exhibiting a power conversion efficiency (PCE) of 1.3% under AM 1.5 conditions (PCE of 2.2% for a 1 cm2 unit cell). Our approach affords trade-offs between power and the active area of the photovoltaic devices, which results in a low-cost power source, and which is scalable to larger areas.A rapid increase in power conversion efficiencies in colloidal quantum dot (QD) solar cells has been achieved recently with lead sulphide (PbS) QDs by adapting a heterojunction architecture, which consists of small-area devices associated with a vacuum-deposited buffer layer with metal electrodes. The preparation of QD solar modules by low-cost solution processes is required to further increase the power-to-cost ratio. Herein we demonstrate all-solution-processed flexible PbS QD solar modules with a layer-by-layer architecture comprising polyethylene terephthalate (PET) substrate/indium tin oxide (ITO)/titanium oxide (TiO2)/PbS QD/poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag, with an active area of up to 30 cm2, exhibiting a power conversion efficiency (PCE) of 1.3% under AM 1.5 conditions (PCE of 2.2% for a 1 cm2 unit cell). Our approach affords trade

Detailed product analysis during the low temperature oxidation of n-butane

PubMed Central

Herbinet, Olivier; Battin-Leclerc, Frédérique; Bax, Sarah; Le Gall, Hervé; Glaude, Pierre-Alexandre; Fournet, René; Zhou, Zhongyue; Deng, Liulin; Guo, Huijun; Xie, Mingfeng; Qi, Fei

2013-01-01

The products obtained from the low-temperature oxidation of n-butane in a jet-stirred reactor (JSR) have been analysed using two methods: gas chromatography analysis of the outlet gas and reflectron time-of-flight mass spectrometry. The mass spectrometer was combined with tunable synchrotron vacuum ultraviolet photoionization and coupled with a JSR via a molecular-beam sampling system. Experiments were performed under quasi-atmospheric pressure, for temperatures between 550 and 800 K, at a mean residence time of 6s and with a stoichiometric n-butane/oxygen/argon mixture (composition = 4/26/70 in mol %). 36 reaction products have been quantified, including addition to the usual oxidation products, acetic acid, hydrogen peroxide, C1, C2 and C4 alkylhydroperoxides and C4 ketohydroperoxides. Evidence of the possible formation of products (dihydrofuranes, furanones) derived from cyclic ethers has also been found. The performance of a detailed kinetic model of the literature has been assessed with the simulation of the formation of this extended range of species. These simulations have also allowed the analysis of possible pathways for the formation of some obtained products. PMID:21031192

Acute health effects after accidental exposure to styrene from drinking water in Spain

PubMed Central

Arnedo-Pena, Alberto; Bellido-Blasco, Juan; Villamarin-Vazquez, Jose-Luis; Aranda-Mares, Jose-Luis; Font-Cardona, Nuria; Gobba, Fabriziomaria; Kogevinas, Manolis

2003-01-01

Objectives We studied subjective health symptoms in a population accidentally exposed to high styrene concentrations in drinking tap water. The contamination occurred during the reparation of a water tank. Methods Residents of 27 apartments in two buildings using the contaminated water were contacted. A questionnaire on subjective symptoms was administered to 84 out of 93 persons living in the apartments at the time of the accident. Styrene concentration was measured in samples of water collected two days after the accident. The means of exposure associated with appearance of symptoms were examined through case-control analyses. Results Styrene in water reached concentrations up to 900 μg/L. Symptoms were reported by 46 persons (attack rate 55 %). The most frequent symptoms were irritation of the throat (26%), nose (19%), eyes (18%) and the skin (14%). General gastrointestinal symptoms were observed with 11% reporting abdominal pain and 7% diarrhea. The factors most strongly associated with symptoms were drinking tap water (OR = 7.8, 95% CI 1.3–48), exposure to vapors from the basement (OR = 10.4, 2.3–47) and eating foods prepared with tap water (OR = 8.6, 1.9–40). All residents in the ground floor reported symptoms. Conclusions This accidental contamination led to very high styrene concentrations in water and was related to a high prevalence of subjective symptoms of the eyes, respiratory tract and skin. Similar exposures have been described in workers but not in subjects exposed at their residence. Various gastrointestinal symptoms were also observed in this population probably due to a local irritative effect. PMID:12777181

Grafting titanium nitride surfaces with sodium styrene sulfonate thin films

PubMed Central

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

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

NASA Astrophysics Data System (ADS)

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.

An enantioselective approach toward 3,4-dihydroisocoumarin through the bromocyclization of styrene-type carboxylic acids.

PubMed

Chen, Jie; Zhou, Ling; Tan, Chong Kiat; Yeung, Ying-Yeung

2012-01-20

A facile and enantioselective approach toward 3,4-dihydroisocoumarin was developed. The method involved an amino-thiocarbamate catalyzed enantioselective bromocyclization of styrene-type carboxylic acids, yielding 3-bromo-3,4-dihydroisocoumarins with good yields and ee's. 3-Bromo-3,4-dihydroisocoumarins are versatile building blocks for various dihydroisocoumarin derivatives in which the Br group can readily be modified to achieve biologically important 4-O-type and 4-N-type 3,4-dihydroisocoumarin systems. In addition, studies indicated that, by refining some parameters, the synthetically useful 5-exo phthalide products could be achieved with good yields and ee's.

Scope and limitations of the Heck-Matsuda-coupling of phenol diazonium salts and styrenes: a protecting-group economic synthesis of phenolic stilbenes.

PubMed

Schmidt, Bernd; Elizarov, Nelli; Berger, René; Hölter, Frank

2013-06-14

4-Phenol diazonium salts undergo Pd-catalyzed Heck reactions with various styrenes to 4'-hydroxy stilbenes. In almost all cases higher yields and fewer side products were observed, compared to the analogous 4-methoxy benzene diazonium salts. In contrast, the reaction fails completely with 2- and 3-phenol diazonium salts. For these substitution patterns the methoxy-substituted derivatives are superior.

Thiopental inhibits nitric oxide production in rat aorta.

PubMed

Castillo, C; Asbun, J; Escalante, B; Villalón, C M; López, P; Castillo, E F

1999-12-01

We studied whether thiopental affects endothelial nitric oxide dependent vasodilator responses and nitrite production (an indicator of nitric oxide production) elicited by acetylcholine, histamine, and A23187 in rat aorta (artery in which nitric oxide is the main endothelial relaxant factor). In addition, we evaluated the barbiturate effect on nitric oxide synthase (NOS) activity in both rat aorta and kidney homogenates. Thiopental (10-100 microg/mL) reversibly inhibited the endothelium-dependent relaxation elicited by acetylcholine, histamine, and A23187. On the contrary, this anesthetic did not modify the endothelium-independent but cGMP-dependent relaxation elicited by sodium nitroprusside (1 nM - 1 microM) and nitroglycerin (1 nM - 1 microM), thus excluding an effect of thiopental on guanylate cyclase of vascular smooth muscle. Thiopental (100 microg/mL) inhibited both basal (87.8+/-14.3%) and acetylcholine- or A23187-stimulated (78.6+/-3.9 and 39.7+/-5.6%, respectively) production of nitrites in aortic rings. In addition the barbiturate inhibited (100 microg/mL) the NOS (45+/-4 and 42.8+/-9%) in aortic and kidney homogenates, respectively (measured as 14C-labeled citrulline production). In conclusion, thiopental inhibition of endothelium-dependent relaxation and nitrite production in aortic rings strongly suggests an inhibitory effect on NOS. Thiopental inhibition of the NOS provides further support to this contention.

Effects of Styrene-Acrylic Sizing on the Mechanical Properties of Carbon Fiber Thermoplastic Towpregs and Their Composites.

PubMed

Bowman, Sean; Jiang, Qiuran; Memon, Hafeezullah; Qiu, Yiping; Liu, Wanshuang; Wei, Yi

2018-03-01

Thermoplastic towpregs are convenient and scalable raw materials for the fabrication of continuous fiber-reinforced thermoplastic matrix composites. In this paper, the potential to employ epoxy and styrene-acrylic sizing agents was evaluated for the making of carbon fiber thermoplastic towpregs via a powder-coating method. The protective effects and thermal stability of these sizing agents were investigated by single fiber tensile test and differential scanning calorimetry (DSC) measurement. The results indicate that the epoxy sizing agent provides better protection to carbon fibers, but it cannot be used for thermoplastic towpreg processing due to its poor chemical stability at high temperature. The bending rigidity of the tows and towpregs with two styrene-acrylic sizing agents was measured by cantilever and Kawabata methods. The styrene-acrylic sized towpregs show low torque values, and are suitable for further processing, such as weaving, preforming, and winding. Finally, composite panels were fabricated directly from the towpregs by hot compression molding. Both of the composite panels show superior flexural strength (>400 MPa), flexural modulus (>63 GPa), and interlaminar shear strength (>27 MPa), indicating the applicability of these two styrene-acrylic sizing agents for carbon fiber thermoplastic towpregs.

Covalent conjugation of graphene oxide with methotrexate and its antitumor activity

NASA Astrophysics Data System (ADS)

Wojtoniszak, M.; Urbas, K.; Perużyńska, M.; Kurzawski, M.; Droździk, M.; Mijowska, E.

2013-05-01

Here, we have functionalized graphene oxide with anticancer drug methotrexate through amide bonding. A kinetics of the drug release from graphene oxide in physiological solution - phosphate buffered saline (PBS) containing different biocompatible polymers have been investigated. Dispersion of MTX-GO in poly sodium-4-styrene sulfonate and poly ethylene glycol resulted in increase of the release time. The material was characterized with transmission electron microscopy, atomic force microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and UV-vis spectroscopy. Furthermore, antineoplastic action against human breast adenocarcinoma cell line MCF7 of MTX-GO and empty graphene oxide was explored.

Styrene-butadiene-styrene copolymer compatibilized carbon black/polypropylene/polystyrene composites with tunable morphology, electrical conduction and rheological stabilities.

PubMed

Song, Yihu; Xu, Chunfeng; Zheng, Qiang

2014-04-21

We report a facile kinetic strategy in combination with styrene-butadiene-styrene (SBS) copolymer compatibilizers for preparing carbon black (CB) filled immiscible polypropylene (PP)/polystyrene (PS) (1/1) blends with finely tuned morphologies and show the important role of location and migration of CB nanoparticles in determining the electrical conductivity and rheological behaviour of the composites. A novel method of mixing a SBS/CB (5/3) masterbatch with the polymers allowed producing composites with CB aggregates dispersed partially in the unfavorable PP phase and partially in the PP side of the interface to exhibit diverse phase connectivity and electrical conductivity depending on the compounding sequences. A cocontinuous morphology with CB enrichment along the interface was formed in the composite prepared by mixing the SBS/CB masterbatch with the premixed PP/PS blend, giving rise to a highest electrical conductivity and dynamic moduli at low frequencies. On the other hand, mixing the masterbatch with one and then with another polymer yielded droplet (PS)-in-matrix (filled PP) composites. The composites underwent phase coalescence and CB redistribution accompanied by marked dynamic electrical conduction and modulus percolations as a function of time during thermal annealing at 180 °C. The composites with the initial droplet-in-matrix morphology progressed anomalously into the cocontinuous morphology, reflecting a common mechanism being fairly nonspecific for understanding the processing of filled multicomponent composites with tailored performances of general concern.

40 CFR 415.600 - Applicability; description of the stannic oxide production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the production of stannic oxide by the reaction of tin metal with air or oxygen. ... stannic oxide production subcategory. 415.600 Section 415.600 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Stannic Oxide Production Subcategory § 415.600 Applicability; description of the stannic...

The development of a micro-shunt made from poly(styrene-block-isobutylene-block-styrene) to treat glaucoma.

PubMed

Pinchuk, Leonard; Riss, Isabelle; Batlle, Juan F; Kato, Yasushi P; Martin, John B; Arrieta, Esdras; Palmberg, Paul; Parrish, Richard K; Weber, Bruce A; Kwon, Yongmoon; Parel, Jean-Marie

2017-01-01

Glaucoma is the second leading cause of blindness with ∼70 million people worldwide who are blind from this disease. The currently practiced trabeculectomy surgery, the gold standard treatment used to stop the progression of vision loss, is rather draconian, traumatic to the patient and requires much surgical skill to perform. This article summarizes the more than 10-year development path of a novel device called the InnFocus MicroShunt®, which is a minimally invasive glaucoma drainage micro-tube used to shunt aqueous humor from the anterior chamber of the eye to a flap formed under the conjunctiva and Tenon's Capsule. The safety and clinical performance of this device approaches that of trabeculectomy. The impetus to develop this device stemmed from the invention of a new biomaterial called poly(styrene-block-isobutylene-block-styrene), or "SIBS." SIBS is ultra-stable with virtually no foreign body reaction in the body, which manifests in the eye as clinically insignificant inflammation and capsule formation. The quest for an easier, safer, and more effective method of treating glaucoma led to the marriage of SIBS with this glaucoma drainage micro-tube. This article summarizes the development of SIBS and the subsequent three iterations of design and four clinical trials that drove the one-year qualified success rate of the device from 43% to 100%. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 211-221, 2017. © 2015 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc.

21 CFR 177.1030 - Acrylonitrile/butadiene/styrene/methyl methacrylate copolymer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... monomer content of the finished copolymer articles is not more than 11 parts per million as determined by a gas chromatographic method titled “Determination of Residual Acrylonitrile and Styrene Monomers... article shall yield not more than 0.0025 milligram per square inch of acrylonitrile monomer when exposed...

Production of biogenic manganese oxides coupled with methane oxidation in a bioreactor for removing metals from wastewater.

PubMed

Matsushita, Shuji; Komizo, Daisuke; Cao, Linh Thi Thuy; Aoi, Yoshiteru; Kindaichi, Tomonori; Ozaki, Noriatsu; Imachi, Hiroyuki; Ohashi, Akiyoshi

2018-03-01

Biogenic manganese oxide (BioMnO x ) can efficiently adsorb various minor metals. The production of BioMnO x in reactors to remove metals during wastewater treatment processes is a promising biotechnological method. However, it is difficult to preferentially enrich manganese-oxidizing bacteria (MnOB) to produce BioMnO x during wastewater treatment processes. A unique method of cultivating MnOB using methane-oxidizing bacteria (MOB) to produce soluble microbial products is proposed here. MnOB were successfully enriched in a methane-fed reactor containing MOB. BioMnO x production during the wastewater treatment process was confirmed. Long-term continual operation of the reactor allowed simultaneous removal of Mn(II), Co(II), and Ni(II). The Co(II)/Mn(II) and Ni(II)/Mn(II) removal ratios were 53% and 19%, respectively. The degree to which Mn(II) was removed indicated that the enriched MnOB used utilization-associated products and/or biomass-associated products. Microbial community analysis revealed that methanol-oxidizing bacteria belonging to the Hyphomicrobiaceae family played important roles in the oxidation of Mn(II) by using utilization-associated products. Methane-oxidizing bacteria were found to be inhibited by MnO 2 , but the maximum Mn(II) removal rate was 0.49 kg m -3  d -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Reduction of nitric oxide and DNA/RNA oxidation products are associated with active disease in systemic lupus erythematosus patients.

PubMed

Iriyoda, T M V; Stadtlober, N; Lozovoy, M A B; Delongui, F; Costa, N T; Reiche, E M V; Dichi, I; Simão, A N C

2017-09-01

The aims of the present study were to evaluate biomarkers of oxidative and nitrosative stress in systemic lupus erythematosus (SLE) patients, in particular products of DNA/RNA oxidative damage and their correlation with disease activity. This study included 188 controls and 203 patients; 153 with inactive SLE (SLEDAI < 6) and 50 with active SLE (SLEDAI ≥ 6) without renal impairment. Oxidative stress was assessed by tert-butyl hydroperoxide-initiated by chemiluminescence, advanced oxidation protein products (AOPP), total radical-trapping antioxidant parameter (TRAP), nitric oxide metabolites (NOx), and DNA/RNA oxidation products. Patients with SLE showed increased oxidative stress, as demonstrated by the augmentation of lipid hydroperoxides ( p < 0.0001) and AOPP ( p < 0.001) and reduced total antioxidant capacity ( p < 0.0001), without differences between patients with active disease and in remission. NOx levels and DNA/RNA oxidation products were inversely and independently associated with disease activity ( p < 0.0001 and p = 0.021, respectively), regardless of BMI and prednisone use. The linear regression analysis showed that about 5% of the SLEDAI score can be explained by the levels of DNA/RNA oxidation products ( r 2 :0.051; p = 0.002) and about 9% of this score by the levels of NOx ( r 2 :0.091; p < 0.0001). This study provides evidence for an inverse association between serum NOx levels and DNA/RNA oxidation products and SLE disease activity, suggesting that oxidative/nitrosative stress markers may be useful in evaluating SLE disease activity and progression of the disease.

Early stages of styrene-isoprene copolymerization in gas phase clusters probed by resonance enhanced multiphoton ionization.

PubMed

Mahmoud, Hatem; Germanenko, Igor N; El-Shall, M Samy

2006-04-06

We present direct evidence for the formation of the covalent bonded styrene (isoprene)(2) oligomer and the isoprene dimer ions following resonance ionization of the gas phase styrene-isoprene binary clusters. The application of resonance ionization to study polymerization reactions in clusters provides new information on the structure and mechanism of formation of the early stages of polymerization and holds considerable promise for the discovery of new initiation mechanisms and for the development of novel materials with unique properties.

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

PubMed

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.

Homogeneous graft copolymerization of styrene onto cellulose in a sulfur dioxide-diethylamine-dimethyl sulfoxide cellulose solvent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsuzuki, M.; Hagiwara, I.; Shiraishi, N.

1980-12-01

Graft copolymerization of styrene onto cellulose was studied in a homogeneous system (SO/sub 2/(liquid)- diethylamine (DEA)-dimethyl sulfoxide (DMSO) medium)) by ..gamma..-ray mutual irradiation technique. At the same time, homopolymerization of styrene was also examined separately in DMSO, SO/sub 2/-DMSO, DEA-DMSO, and SO/sub 2/-DEA-DMSO media by the same technique. Polymerization of styrene hardly occurs on concentrations above 10 mole SO/sub 2/-DEA complex per mole glucose unit. Maximum percent grafting was obtained in concentrations of 4 mole, after which it decreased rapidly. Total conversion and percent grafting increased with the irradiation time. The value (=0.55) of the slope of the total conversionmore » rate plotted against the dose was only a little higher than the 1/2 which was expected from normal kinetics. No retardation in homopolymerization of styrene in DMSO, SO/sub 2/-DMSO, and DEA-DMSO was evident, while the retardation of homopolymerization in the SO/sub 2/-DEA-DMSO medium was measurable. Sulfur atoms were detected in the polymers obtained in both of SO/sub 2/-DMSO and SO/sub 2/-DEA-DMSO solutions. All of the molecular weights of polymers obtained in the present experiment were very low (3.9 x 10/sup 3/-1.75 x 10/sup 4/).« less

High performance graphene oxide based rubber composites.

PubMed

Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W; Zhang, Liqun; Liang, Yongri; Liu, Li

2013-01-01

In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

Abiotic Nitrous Oxide Production in Natural and Artificial Seawater

NASA Astrophysics Data System (ADS)

Ochoa, H.; Stanton, C. L.; Cavazos, A. R.; Ostrom, N. E.; Glass, J. B.

2014-12-01

The ocean contributes approximately one third of global sources of nitrous oxide (N2O) to the atmosphere. While nitrification is thought to be the dominant pathway for marine N2O production, mechanisms remain unresolved. Previous studies have carried the implicit assumption that marine N2O originates directly from enzymatic sources. However, abiotic production of N2O is possible via chemical reactions between nitrogenous intermediates and redox active trace metals in seawater. In this study, we investigated N2O production and isotopic composition in treatments with and without added hydroxylamine (NH2OH) and nitric oxide (NO), intermediates in microbial oxidation of ammonia to nitrite, and Fe(III). Addition of substrates to sterile artificial seawater was compared with filtered and unfiltered seawater from Sapelo Island, coastal Georgia, USA. N2O production was observed immediately after addition of Fe(III) in the presence of NH2OH at pH 8 in sterile artificial seawater. Highest N2O production was observed in the presence of Fe(III), NO, and NH2OH. The isotopomer site preference of abiotically produced N2O was consistent with previous studies (31 ± 2 ‰). Higher abiotic N2O production was observed in sterile artificial seawater (salinity: 35 ppt) than filtered Sapelo Island seawater (salinity: 25 ppt) whereas diluted sterile artificial seawater (18 ppt) showed lowest N2O production, suggesting that higher salinity promotes enhanced abiotic N2O production. Addition of Fe(III) to unfiltered Sapelo Island seawater stimulated N2O production. The presence of ammonia-oxidizing archaea (AOA), which lack known N2O producing enzymes, in Sapelo Island seawater was confirmed by successful amplification of the archaeal amoA gene, whereas ammonia-oxidizing bacteria (AOB), which contain N2O-producing enzymes were undetected. Given the few Fe-containing proteins present in AOA, it is likely that Fe(III) addition promoted N2O production via an abiotic vs. enzymatic N2O mechanism

Chitosan/polyanion surface modification of styrene-butadiene-styrene block copolymer membrane for wound dressing.

PubMed

Yang, Jen Ming; Yang, Jhe-Hao; Huang, Huei Tsz

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(-) and OCN 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±8g/day·m(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(-) and OCN 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(-) and OCN 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 these [CS/polyanion] membranes was also conducted

Reactivity of Metal Oxide Sorbents for Removal of H{sub 2}S

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, K.C.; Crowe, E.R.

1996-12-31

Removal of hydrogen sulfide contained in hot coal gases produced from integrated gasification combined cycle power generation systems is required to protect downstream combustion turbines from being corroded with sulfur compounds. Removal of sulfur compounds from hot coal gas products is investigated by using various metal oxide sorbents and membrane separation methods. The main requirements of these metal oxide sorbents are durability and high sulfur loading capacity during absorption-regeneration cycles. In this research, durable metal oxide sorbents were formulated. Reactivity of the formulated metal oxide sorbents with simulated coal gas mixtures was examined to search for an ideal sorbent formulationmore » with a high-sulfur loading capacity suitable for removal of hydrogen sulfide from coal gases. The main objectives of this research are to formulate durable metal oxide sorbents with high-sulfur loading capacity by a physical mixing method, to investigate reaction kinetics on the removal of sulfur compounds from coal gases at high temperature and pressure, to study reaction kinetics on the regeneration of sulfided sorbents, to identify effects of hydrogen partial pressures and moisture on equilibrium/dynamic absorption of hydrogen sulfide into formulated metal oxide sorbents as well as initial reaction rates of H{sub 2}S with formulated metal oxide sorbents, and to evaluate intraparticular diffusivity of H{sub 2}S into formulated sorbents at various reaction conditions. The metal oxide sorbents such as TU-1, TU-19, TU-24, TU-25 and TU-28 were formulated with zinc oxide powder as an active sorbent ingredient, bentonite as a binding material and titanium oxide as a supporting metal oxide.« less

Consumer exposure to substances in plastic packaging. I. Assessment of the contribution of styrene from yogurt pots.

PubMed

Vitrac, Olivier; Leblanc, Jean-Charles

2007-02-01

A generic methodology for the assessment of consumer exposure to substances migrating from packaging materials into foodstuffs during storage is presented. Consumer exposure at the level of individual households is derived from the probabilistic modeling of the contamination of all packed food product units (e.g. yogurt pot, milk bottle, etc.) consumed by a given household over 1 year. Exposure of a given population is estimated by gathering the exposure distributions of individual households to suitable weights (conveniently, household sizes). Calculations are made by combining (i) an efficient resolution of migration models and (ii) a methodology utilizing different sources of uncertainty and variability. The full procedure was applied to the assessment of consumer exposure to styrene from yogurt pots based on yearly purchase data of more than 5400 households in France (about 2 million yogurt pots) and an initial concentration c0 of styrene in yogurt pot walls, which is assumed to be normally distributed with an average value of 500 mg kg-1 and a standard deviation of 150 mg kg-1. Results are discussed regarding both sensitivity of the migration model to boundary conditions and household practices. By assuming a partition coefficient of 1 and a Biot number of 100, the estimated median household exposure to styrene ranged between 1 and 35 microg day-1 person-1 (5th and 95th percentiles) with a likely value of 12 microg day-1 person-1 (50th percentile). It was found that exposure does not vary independently with the average consumption rate and contact times. Thus, falsely assuming a uniform contact time equal to the sell-by-date for all yogurts overestimates significantly the daily exposure (5th and 95th percentiles of 2 and 110 microg day-1 person-1, respectively) since high consumers showed quicker turnover of stock.

Emissions of putative isoprene oxidation products from mango branches under abiotic stress

PubMed Central

Jardine, Kolby J.; Meyers, Kimberly; Abrell, Leif; Alves, Eliane G.; Yanez Serrano, Ana Maria; Kesselmeier, Jürgen; Karl, Thomas; Guenther, Alex; Vickers, Claudia; Chambers, Jeffrey Q.

2013-01-01

Although several per cent of net carbon assimilation can be re-released as isoprene emissions to the atmosphere by many tropical plants, much uncertainty remains regarding its biological significance. In a previous study, we detected emissions of isoprene and its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) from tropical plants under high temperature/light stress, suggesting that isoprene is oxidized not only in the atmosphere but also within plants. However, a comprehensive analysis of the suite of isoprene oxidation products in plants has not been performed and production relationships with environmental stress have not been described. In this study, putative isoprene oxidation products from mango (Mangifera indica) branches under abiotic stress were first identified. High temperature/light and freeze–thaw treatments verified direct emissions of the isoprene oxidation products MVK and MACR together with the first observations of 3-methyl furan (3-MF) and 2-methyl-3-buten-2-ol (MBO) as putative novel isoprene oxidation products. Mechanical wounding also stimulated emissions of MVK and MACR. Photosynthesis under 13CO2 resulted in rapid (<30min) labelling of up to five carbon atoms of isoprene, with a similar labelling pattern observed in the putative oxidation products. These observations highlight the need to investigate further the mechanisms of isoprene oxidation within plants under stress and its biological and atmospheric significance. PMID:23881400

Emissions of putative isoprene oxidation products from mango branches under abiotic stress.

PubMed

Jardine, Kolby J; Meyers, Kimberly; Abrell, Leif; Alves, Eliane G; Yanez Serrano, Ana Maria; Kesselmeier, Jürgen; Karl, Thomas; Guenther, Alex; Chambers, Jeffrey Q; Vickers, Claudia

2013-09-01

Although several per cent of net carbon assimilation can be re-released as isoprene emissions to the atmosphere by many tropical plants, much uncertainty remains regarding its biological significance. In a previous study, we detected emissions of isoprene and its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) from tropical plants under high temperature/light stress, suggesting that isoprene is oxidized not only in the atmosphere but also within plants. However, a comprehensive analysis of the suite of isoprene oxidation products in plants has not been performed and production relationships with environmental stress have not been described. In this study, putative isoprene oxidation products from mango (Mangifera indica) branches under abiotic stress were first identified. High temperature/light and freeze-thaw treatments verified direct emissions of the isoprene oxidation products MVK and MACR together with the first observations of 3-methyl furan (3-MF) and 2-methyl-3-buten-2-ol (MBO) as putative novel isoprene oxidation products. Mechanical wounding also stimulated emissions of MVK and MACR. Photosynthesis under (13)CO2 resulted in rapid (<30 min) labelling of up to five carbon atoms of isoprene, with a similar labelling pattern observed in the putative oxidation products. These observations highlight the need to investigate further the mechanisms of isoprene oxidation within plants under stress and its biological and atmospheric significance.

Emissions of putative isoprene oxidation products from mango branches under abiotic stress

DOE PAGES

Jardine, Kolby J.; Meyers, Kimberly; Abrell, Leif; ...

2013-07-23

Although several per cent of net carbon assimilation can be re-released as isoprene emissions to the atmosphere by many tropical plants, much uncertainty remains regarding its biological significance. In a previous study, we detected emissions of isoprene and its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) from tropical plants under high temperature/light stress, suggesting that isoprene is oxidized not only in the atmosphere but also within plants. However, a comprehensive analysis of the suite of isoprene oxidation products in plants has not been performed and production relationships with environmental stress have not been described. In this study, putativemore » isoprene oxidation products from mango (Mangifera indica) branches under abiotic stress were first identified. High temperature/light and freeze–thaw treatments verified direct emissions of the isoprene oxidation products MVK and MACR together with the first observations of 3-methyl furan (3-MF) and 2-methyl-3-buten-2-ol (MBO) as putative novel isoprene oxidation products. Mechanical wounding also stimulated emissions of MVK and MACR. Photosynthesis under 13CO 2 resulted in rapid (<30min) labelling of up to five carbon atoms of isoprene, with a similar labelling pattern observed in the putative oxidation products. These observations highlight the need to investigate further the mechanisms of isoprene oxidation within plants under stress and its biological and atmospheric significance.« less

Emissions of putative isoprene oxidation products from mango branches under abiotic stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jardine, Kolby J.; Meyers, Kimberly; Abrell, Leif

Although several per cent of net carbon assimilation can be re-released as isoprene emissions to the atmosphere by many tropical plants, much uncertainty remains regarding its biological significance. In a previous study, we detected emissions of isoprene and its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) from tropical plants under high temperature/light stress, suggesting that isoprene is oxidized not only in the atmosphere but also within plants. However, a comprehensive analysis of the suite of isoprene oxidation products in plants has not been performed and production relationships with environmental stress have not been described. In this study, putativemore » isoprene oxidation products from mango (Mangifera indica) branches under abiotic stress were first identified. High temperature/light and freeze–thaw treatments verified direct emissions of the isoprene oxidation products MVK and MACR together with the first observations of 3-methyl furan (3-MF) and 2-methyl-3-buten-2-ol (MBO) as putative novel isoprene oxidation products. Mechanical wounding also stimulated emissions of MVK and MACR. Photosynthesis under 13CO 2 resulted in rapid (<30min) labelling of up to five carbon atoms of isoprene, with a similar labelling pattern observed in the putative oxidation products. These observations highlight the need to investigate further the mechanisms of isoprene oxidation within plants under stress and its biological and atmospheric significance.« less

The influences of ammonia on aerosol formation in the ozonolysis of styrene: roles of Criegee intermediate reactions

PubMed Central

Ma, Qiao; Lin, Xiaoxiao; Yang, Chengqiang; Long, Bo; Zhang, Weijun

2018-01-01

The influences of ammonia (NH3) on secondary organic aerosol (SOA) formation from ozonolysis of styrene have been investigated using chamber experiments and quantum chemical calculations. With the value of [O3]0/[styrene]0 ratios between 2 and 4, chamber experiments were carried out without NH3 or under different [NH3]/[styrene]0 ratios. The chamber experiments reveal that the addition of NH3 led to significant decrease of SOA yield. The overall SOA yield decreased with the [NH3]0/[styrene]0 increasing. In addition, the addition of NH3 at the beginning of the reaction or several hours after the reaction occurs had obviously different influence on the yield of SOA. Gas phase reactions of Criegee intermediates (CIs) with aldehydes and NH3 were studied in detail by theoretical methods to probe into the mechanisms behind these phenomena. The calculated results showed that 3,5-diphenyl-1,2,4-trioxolane, a secondary ozonide formed through the reactions of C6H5ĊHOO· with C6H5CHO, could make important contribution to the aerosol composition. The addition of excess NH3 may compete with aldehydes, decreasing the secondary ozonide yield to some extent and thus affect the SOA formation. PMID:29892406

Immobilization of styrene-substituted 1,3,4-oxadiazoles into thermoreversible luminescent organogels and their unexpected photocatalyzed rearrangement.

PubMed

Dumur, Frédéric; Contal, Emmanuel; Wantz, Guillaume; Phan, Trang N T; Bertin, Denis; Gigmes, Didier

2013-01-21

A series of styrene-substituted 1,3,4-oxadiazoles has been designed and investigated as new low-molecular-weight organogelators. The photophysical properties of the resulting thermoreversible organogels have been characterized by UV/Vis absorption and luminescence spectroscopies. Surprisingly, the gelation ability of the oxadiazoles depended on the presence of the styrene moiety as gelation of the investigated oxadiazoles did not take place in its absence. Gel formation was accompanied by a modification of the fluorescence of the organogelators in the supramolecular state. UV irradiation of the gels caused a rearrangement of the immobilized 1,3,4-oxadiazoles bearing a styrene moiety by a tandem [4+2] and [3+2] cascade reaction. Structure modification and color change of the gels were also evident upon irradiation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental data on compressive strength and durability of sulfur concrete modified by styrene and bitumen.

PubMed

Dehestani, M; Teimortashlu, E; Molaei, M; Ghomian, M; Firoozi, S; Aghili, S

2017-08-01

In this data article experimental data on the compressive strength, and the durability of styrene and bitumen modified sulfur concrete against acidic water and ignition are presented. The percent of the sulfur cement and the gradation of the aggregates used are according to the ACI 548.2R-93 and ASTM 3515 respectively. For the styrene modified sulfur concrete different percentages of styrene are used. Also for the bitumen modified sulfur concrete, different percentages of bitumen and the emulsifying agent (triton X-100) are utilized. From each batch three 10×10×10 cm cubic samples were casted. One of the samples was used for the compressive strength on the second day of casting, and one on the twenty-eighth day. Then the two samples were put under the high pressure flame of the burning liquid gas for thirty seconds and their ignition resistances were observed. The third sample was put into the acidic water and after twenty eight days immersion in water was dried in the ambient temperature. After drying its compressive strength has been evaluated.

Amino Acid Degradations Produced by Lipid Oxidation Products.

PubMed

Hidalgo, Francisco J; Zamora, Rosario

2016-06-10

Differently to amino acid degradations produced by carbohydrate-derived reactive carbonyls, amino acid degradations produced by lipid oxidation products are lesser known in spite of being lipid oxidation a major source of reactive carbonyls in food. This article analyzes the conversion of amino acids into Strecker aldehydes, α-keto acids, and amines produced by lipid-derived free radicals and carbonyl compounds, as well as the role of lipid oxidation products on the reactions suffered by these compounds: the formation of Strecker aldehydes and other aldehydes from α-keto acids; the formation of Strecker aldehydes and olefins from amines; the formation of shorter aldehydes from Strecker aldehydes; and the addition reactions suffered by the olefins produced from the amines. The relationships among all these reactions and the effect of reaction conditions on them are discussed. This knowledge should contribute to better control food processing in order to favor the formation of desirable beneficial compounds and to inhibit the production of compounds with deleterious properties.

Volatile profile, lipid oxidation and protein oxidation of irradiated ready-to-eat cured turkey meat products

NASA Astrophysics Data System (ADS)

Feng, Xi; Ahn, Dong Uk

2016-10-01

Irradiation had little effects on the thiobarbituric acid reactive substances (TBARS) values in ready-to-eat (RTE) turkey meat products, while it increased protein oxidation at 4.5 kGy. The volatile profile analyses indicated that the amount of sulfur compounds increased linearly as doses increased in RTE turkey meat products. By correlation analysis, a positive correlation was found between benzene/ benzene derivatives and alcohols with lipid oxidation, while aldehydes, ketones and alkane, alkenes and alkynes were positively correlated with protein oxidation. Principle component analysis showed that irradiated meat samples can be discriminated by two categories of volatile compounds: Strecker degradation products and radiolytic degradation products. The cluster analysis of volatile data demonstrated that low-dose irradiation had minor effects on the volatile profile of turkey sausages (<1.5 kGy). However, as the doses increased, the differences between the irradiated and non-irradiated cured turkey products became significant.

Properties of styrene-maleic anhydride copolymers containing wood-based fillers

Treesearch

John Simonsen; Rodney Jacobson; Roger Rowell

1998-01-01

Recycled newsprint (ONP) and dry process aspen fiber were combined with styrene maleic anhydride (SMA) copolymers containing either 7 or 14 percent maleic anhydride. The fiber-filled SMA composites were equivalent or superior to unfilled SMA in strength, stiffness, and notched Izod impact strength. ONP performed surprisingly well as a filler. Unnotched Izod impact...

Molecular and morphological characterization of midblock-sulfonated styrenic triblock copolymers

DOE PAGES

Mineart, Kenneth P.; Ryan, Justin J.; Lee, Byeongdu; ...

2017-01-11

Midblock-sulfonated triblock copolymers afford a desirable opportunity to generate network-forming amphiphilic materials that are suitable for use in a wide range of emerging technologies as fuel-cell, water-desalination, ion-exchange, photovoltaic, or electroactive membranes. Employing a previously reported synthetic strategy wherein poly( p- tert-butylstyrene) remains unreactive, we have selectively sulfonated the styrenic midblock of a poly( p- tert-butylstyrene- b-styrene- b- p- tert- butylstyrene) (TST) triblock copolymer to different extents. Comparison of the resulting sulfonated copolymers with results from our prior study provides favorable quantitative agreement and suggests that a shortened reaction time is advantageous. An ongoing challenge regarding the morphological development ofmore » charged block copolymers is the competition between microphase separation of the incompatible blocks and physical cross-linking of ionic clusters, with the latter often hindering the former. Here, we expose the sulfonated TST copolymers to solvent-vapor annealing to promote nanostructural refinement. Furthermore, the effect of such annealing on morphological characteristics, as well as on molecular free volume, is explored.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Canfield, R.C.; Cox, R.C.; McCarthy, D.M.

Cumene is manufactured by the alkylation of benzene with propylene and is used almost exclusively as a feedstock for phenol production via the cumene oxidation route. Monsanto's interest in cumene process development dates back to the 60's and 70's when it was a major U.S. producer of both cumene and phenol. Lummus Crest's interest in cumene relates to its position in phenol technology. Interestingly, however, the new Monsanto/Lummus Crest process is more a result of Monsanto and Lummus Crest's research in ethylbenezene/styrene than in cumene.

Co-polymerization of methyl methacrylate and styrene via surfactant-free emulsion polymerization, as a potential material for photonic crystal application

NASA Astrophysics Data System (ADS)

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.

Oxidation of iopamidol with ferrate (Fe(VI)): Kinetics and formation of toxic iodinated disinfection by-products.

PubMed

Dong, Huiyu; Qiang, Zhimin; Liu, Shaogang; Li, Jin; Yu, Jianwei; Qu, Jiuhui

2018-03-01

Presence of iodinated X-ray contrast media (ICMs) in source water is of high concern, because of their potential to form highly toxic iodinated disinfection by-products (I-DBPs). This study investigated kinetics, mechanisms and products for oxidation of one ICMs, iopamidol (IPM) by ferrate (Fe(VI)). The obtained apparent second-order rate constants for oxidation of IPM by Fe(VI) ranged from 0.7 M -1  s -1 to 74.6 M -1  s -1  at pH 6.0-10.0, which were highly dependent on pH. It was found that the oxidation of IPM by Fe(VI) led to the formation of highly toxic I-DBPs. Iodoform (IF), iodoacetic acid and triiodoacetic acid formations were observed during the oxidation and IF dominated the formed I-DBPs. The formation of I-DBPs was also governed by pH and the maximum formation of I-DBPs occurred at pH 9.0. Transformation pathways of IPM by Fe(VI) oxidation were speculated to proceed through deiodination, amide hydrolysis and oxidation of amine reactions. The deiodination reaction during the oxidation of IPM by Fe(VI) contributed to the formation of I-DBPs. The formation of I-DBPs during the oxidation of IPM by Fe(VI) was significantly higher than those of iohexol, diatrizoate and iopromide, which was consistent with the lowest molecular orbital energy gap of IPM. Although Fe(VI) is considered as a green oxidant, the formation of highly toxic I-DBPs during the oxidation of IPM should receive great attention. Copyright © 2017 Elsevier Ltd. All rights reserved.

Increased 5S rRNA oxidation in Alzheimer's disease.

PubMed

Ding, Qunxing; Zhu, Haiyan; Zhang, Bing; Soriano, Augusto; Burns, Roxanne; Markesbery, William R

2012-01-01

It is widely accepted that oxidative stress is involved in neurodegenerative disorders such as Alzheimer's disease (AD). Ribosomal RNA (rRNA) is one of the most abundant molecules in most cells and is affected by oxidative stress in the human brain. Previous data have indicated that total rRNA levels were decreased in the brains of subjects with AD and mild cognitive impairment concomitant with an increase in rRNA oxidation. In addition, level of 5S rRNA, one of the essential components of the ribosome complex, was significantly lower in the inferior parietal lobule (IP) brain area of subjects with AD compared with control subjects. To further evaluate the alteration of 5S rRNA in neurodegenerative human brains, multiple brain regions from both AD and age-matched control subjects were used in this study, including IP, superior and middle temporal gyro, temporal pole, and cerebellum. Different molecular pools including 5S rRNA integrated into ribosome complexes, free 5S rRNA, cytoplasmic 5S rRNA, and nuclear 5S rRNA were studied. Free 5S rRNA levels were significantly decreased in the temporal pole region of AD subjects and the oxidation of ribosome-integrated and free 5S rRNA was significantly increased in multiple brain regions in AD subjects compared with controls. Moreover, a greater amount of oxidized 5S rRNA was detected in the cytoplasm and nucleus of AD subjects compared with controls. These results suggest that the increased oxidation of 5S rRNA, especially the oxidation of free 5S rRNA, may be involved in the neurodegeneration observed in AD.

Adsorption and covalent binding of fibrinogen as a method for probing the chemical composition of poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) microsphere surfaces.

PubMed

Gosecka, Monika; Chehimi, Mohamed M; Basinska, Teresa; Slomkowski, Stanislaw; Makowski, Tomasz

2017-12-01

We investigated the distribution of polyglycidol and polystyrene on the surface of poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) microspheres (random distribution or segregated into hydrophilic and hydrophobic patches), using fibrinogen (Fb) as a macromolecular probe. The fibrinogen was adsorbed or covalently attached to the surface of the poly(styrene-co-α-tert-butoxy-ω-vinylbenzyl-polyglycidol) (P(S/PGLy)) microspheres. The P(S/PGLy) particles were prepared by emulsion copolymerization of styrene and α-tert-butoxy-ω-vinylbenzyl-polyglycidol (PGLy) macromonomer initiated with potassium persulfate. The polymerizations yielded P(S/PGLy) particles with various surface fractions of polyglycidol, depending on the amount of added macromonomer and the addition process. In some syntheses, the entire macromonomer amount was added once at the beginning of the polymerization, while in others, the macromonomer was added gradually after the formation of particle seeds from pure polystyrene. XPS studies revealed that the fraction of polyglycidol in the interfacial layer of the microspheres was larger when the entire amount of macromonomer was added at the beginning of the polymerization than when it was added after formation of the polystyrene seeds. Studies of fibrinogen adsorption provided the first evidence of segregation of the hydrophobic (polystyrene) and hydrophilic (polyglycidol) components at the surface of the composite P(S/PGLy) microspheres into patches. The hydrophobic patches are composed mainly of polystyrene. However, they also contain a small amount of polyglycidol chains, making the adsorption of fibrinogen weaker than the adsorption onto the pure polystyrene. Studies of covalent immobilization of fibrinogen on the microspheres via 1,3,5-trichlorotriazine confirmed these findings. Copyright © 2017 Elsevier B.V. All rights reserved.

Oxidation of a [Cu2S] complex by N2O and CO2: insights into a role of tetranuclearity in the CuZ site of nitrous oxide reductase.

PubMed

Bagherzadeh, Sharareh; Mankad, Neal P

2018-01-25

Oxidation of a [Cu 2 (μ-S)] complex by N 2 O or CO 2 generated a [Cu 2 (μ-SO 4 )] product. In the presence of a sulfur trap, a [Cu 2 (μ-O)] species also formed from N 2 O. A [Cu 2 (μ-CS 3 )] species derived from CS 2 modeled initial reaction intermediates. These observations indicate that one role of tetranuclearity in the Cu Z catalytic site of nitrous oxide reductase is to protect the crucial S 2- ligand from oxidation.

Acute biotoxic effect of styrene on rat liver. Correlation with enzyme-mediated mutagenicity of benzpyrene and acrylonitrile.

PubMed

Roberfroid, M; Poncelet, F; Lambotte-Vandepaer, M; Duverger-Van Bogaert, M; de Meester, C; Mercier, M

1978-01-01

Styrene is commonly used in western Europe for the manufacture of plastics suitable for packaging foodstuffs. This report demonstrates that, injected intraperitoneally at a dose as low as 10 mg/kg, styrene modifies the catalytic properties of aryl hydrocarbon hydroxylase by reducing its KM value. A similar effect is reported for two potent chemical carcinogens, 3-methylcholanthrene and benzo(a)pyrene. Ethylbenzene and benzo(e)pyrene and phenobarbital do not produce the same effect. Pretreatments of the rats with chemicals which modify aryl hydrocarbon hydroxylase also increase the capacity of the liver enzymes to activate benzopyrene to a mutagenic intermediate in vitro, as measured by the Ames test for mutagenicity. Exposure to both styrene and the other modifiers of the xenobiotic-metabolizing enzymes could thus influence the carcinogenic and toxic effects of chemicals which are activated by these enzymes. This hypothesis needs further investigation.

Oxidation driven ZnS Core-ZnO shell photocatalysts under controlled oxygen atmosphere for improved photocatalytic solar water splitting

NASA Astrophysics Data System (ADS)

Bak, Daegil; Kim, Jung Hyeun

2018-06-01

Zinc type photocatalysts attract great attentions in solar hydrogen production due to their easy availability and benign environmental characteristics. Spherical ZnS particles are synthesized with a facile hydrothermal method, and they are further used as core materials to introduce ZnO shell layer surrounding the core part by partial oxidation under controlled oxygen contents. The resulting ZnS core-ZnO shell photocatalysts represent the heterostructural type II band alignment. The existence of oxide layer also influences on proton adsorption power with an aid of strong base cites derived from highly electronegative oxygen atoms in ZnO shell layer. Photocatalytic water splitting reaction is performed to evaluate catalyst efficiency under standard one sun condition, and the highest hydrogen evolution rate (1665 μmolg-1h-1) is achieved from the sample oxidized at 16.2 kPa oxygen pressure. This highest hydrogen production rate is achieved in cooperation with increased light absorption and promoted charge separations. Photoluminescence analysis reveals that the improved visible light response is obtained after thermal oxidation process due to the oxygen vacancy states in the ZnO shell layer. Therefore, overall photocatalytic efficiency in solar hydrogen production is enhanced by improved charge separations, crystallinity, and visible light responses from the ZnS core-ZnO shell structures induced by thermal oxidation.

Domino-Fluorination-Protodefluorination Enables Decarboxylative Cross-Coupling of α-Oxocarboxylic Acids with Styrene via Photoredox Catalysis.

PubMed

Zhang, Muliang; Xi, Junwei; Ruzi, Rehanguli; Li, Nan; Wu, Zhongkai; Li, Weipeng; Zhu, Chengjian

2017-09-15

Domino-fluorination-protodefluorination decarboxylative cross-coupling of α-keto acids with styrene has been developed via photoredox catalysis. The critical part of this strategy is the formation of the carbon-fluorine (C-F) bond by the capture of a carbon-centered radical intermediate, which will overcome side reactions during the styrene radical functionalization process. Experimental studies have provided evidence indicating a domino-fluorination-protodefluorination pathway with α-keto acid initiating the photoredox cycle. The present catalytic protocol also affords a novel approach for the construction of α,β-unsaturated ketones under mild conditions.

Design and testing of digitally manufactured paraffin Acrylonitrile-butadiene-styrene hybrid rocket motors

NASA Astrophysics Data System (ADS)

McCulley, Jonathan M.

This research investigates the application of additive manufacturing techniques for fabricating hybrid rocket fuel grains composed of porous Acrylonitrile-butadiene-styrene impregnated with paraffin wax. The digitally manufactured ABS substrate provides mechanical support for the paraffin fuel material and serves as an additional fuel component. The embedded paraffin provides an enhanced fuel regression rate while having no detrimental effect on the thermodynamic burn properties of the fuel grain. Multiple fuel grains with various ABS-to-Paraffin mass ratios were fabricated and burned with nitrous oxide. Analytical predictions for end-to-end motor performance and fuel regression are compared against static test results. Baseline fuel grain regression calculations use an enthalpy balance energy analysis with the material and thermodynamic properties based on the mean paraffin/ABS mass fractions within the fuel grain. In support of these analytical comparisons, a novel method for propagating the fuel port burn surface was developed. In this modeling approach the fuel cross section grid is modeled as an image with white pixels representing the fuel and black pixels representing empty or burned grid cells.

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

PubMed

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 (K L 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. K L 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 K L 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.

Oxidant induced alteration of carbohydrate production and allocation in plants

Treesearch

Robert L. Heath

1998-01-01

Urban air basin produced oxidants, notably ozone, induce a decline in productivity in plants. This loss of productivity is manifested by slower growth, hindered development, lower reproduction rates, impaired ability to resist disease, and other stresses. While many metabolic events have been linked to oxidant exposure, three major shifts have been well-studied:...

Arginine supplementation induces myoblast fusion via augmentation of nitric oxide production.

PubMed

Long, Jodi H D; Lira, Vitor A; Soltow, Quinlyn A; Betters, Jenna L; Sellman, Jeff E; Criswell, David S

2006-01-01

The semi-essential amino acid, L-arginine (L-Arg), is the substrate for endogenous synthesis of nitric oxide, a molecule that is involved in myoblast proliferation and fusion. Since L-Arg supply may limit nitric oxide synthase (NOS) activity in endothelial cells, we examined L-Arg supplementation in differentiating mouse myoblasts and tested the hypothesis that L-Arg exerts direct effects on myoblast fusion via augmentation of endogenous nitric oxide production. C(2)C(12) myoblasts in differentiation media received one of the following treatments for 120 h: 1 mM L-Arg, 0.1 mM N-nitro-L-arginine methyl ester (L-NAME), L-Arg + L-NAME, 10 mM L-Lysine, or no supplement (Control). Cultures were fixed and stained with hematoxylin and eosin for microphotometric image analysis of myotube density, nuclear density, and fusion index (% of total nuclei in myotubes). Endogenous production of nitric oxide during the treatment period peaked between 24 and 48 h. L-Arg amplified nitric oxide production between 0 and 24 h and increased myotube density, total nuclei number, and nuclear fusion index. These L-Arg effects were prevented by the NOS inhibitor, L-NAME. Further, L-Lysine, a competitive inhibitor of L-Arg uptake, repressed nitric oxide production and reduced myotube density and fusion index. In summary, L-Arg augments myotube formation and increases nitric oxide production in a process limited by cellular L-Arg uptake.

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

PubMed

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 (T m ) 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.

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

PubMed Central

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

2012-01-01

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. PMID:24688940

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

PubMed

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.

Oxidation of cefazolin by potassium permanganate: Transformation products and plausible pathways.

PubMed

Li, Liping; Wei, Dongbin; Wei, Guohua; Du, Yuguo

2016-04-01

Cefazolin was demonstrated to exert high reactivity toward permanganate (Mn(VII)), a common oxidant in water pre-oxidation treatment. In this study, five transformation products were found to be classified into three categories according to the contained characteristic functional groups: three (di-)sulfoxide products, one sulfone product and one di-ketone product. Products analyses showed that two kinds of reactions including oxidation of thioether and the cleavage of unsaturated CC double bond occurred during transformation of cefazolin by Mn(VII). Subsequently, the plausible transformation pathways under different pH conditions were proposed based on the identified products and chemical reaction principles. More importantly, the simulation with real surface water matrix indicated that the proposed transformation pathways of cefazolin could be replayed in real water treatment practices. Copyright © 2016 Elsevier Ltd. All rights reserved.

Visible Light Photocatalysis of [2+2] Styrene Cycloadditions via Energy Transfer

PubMed Central

Lu, Zhan; Yoon, Tehshik P.

2012-01-01

Hip to be square: Styrenes participate in [2+2] cycloadditions upon irradiation with visible light in the presence of an iridium(III) polypyridyl complex. In contrast to previous reports of visible light photoredox catalysis, the mechanism of this process involves photosensitization by energy transfer and not electron transfer. PMID:22965321

Fact and Fiction of Nitrous Oxide Production By Nitrification

NASA Astrophysics Data System (ADS)

Stein, L. Y.; Kozlowski, J.; Stieglmeier, M.; Klotz, M. G.; Schleper, C.

2014-12-01

An accepted dogma in nitrification research is that ammonia-oxidizing bacteria (AOB) produce a modicum of nitrous oxide (N2O) during nitritation via incomplete oxidation of hydroxylamine, and substantially more at low oxygen concentrations via nitrifier denitrification.The nitrifier denitrification pathway involves the reduction of nitrite to N2O via nitric oxide and was thought to require activities of a copper-containing nitrite reductase (NirK) and nitric oxide reductase (NorB); inventory encoded in most, but not all AOB genome sequences. The discovery of nirK genes in ammonia-oxidizing Thaumarchaeota (AOA) resulted in a slew of publications stating that AOA must also perform nitrifier denitrification and, due to their high abundance, must control the majority of nitrification-linked N2O emissions. Prior to a publication by Stieglmeier et al. (2014), which definitively showed a lack of nitrifier denitrification by two axenic AOA cultures, other researchers relied on enrichment cultures, negative data, and heavy inferencing without direct demonstration of either a functional pathway or involvement of specific genes or enzymes. AOA genomes lack recognizable nitric oxide reductases and thermophilic AOA also lack nirK genes. Physiological and microrespirometry experiments with axenic AOB and AOA cultures allowed us to demonstrate that: 1) AOB produce N2O via nitrifier denitrification even though some lack annotated nirK and/or norB genes; 2) nitrifier denitrification by AOB is reliant on nitric oxide but ammonia oxidation is not; 3) ammonia oxidation by AOA is reliant on production of nitric oxide; 4) AOA are incapable of generating N2O via nitrifier denitrification; 5) N2O production by AOA is from chemical interactions between NO and media components, most likely not by enzyme activity. Our results reveal operation of different N oxide transformation pathways in AOB and AOA governed by different environmental controls and involving different mechanisms of N2O

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

EPA Science Inventory

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 ...

Computational investigation of the photochemical deoxygenation of thiophene-S-oxide and selenophene-Se-oxide.

PubMed

Stoffregen, Stacey A; Lee, Stephanie Y; Dickerson, Pearl; Jenks, William S

2014-02-01

CASSCF and multireference MP2 calculations were carried out on thiophene-S-oxide (TO) and selenophene-Se-oxide (SeO), comparing the energies of the ground state to the first two electronically excited singlet and triplet states, using constrained optimizations and multiple fixed S-O or Se-O distances. For both molecules, one of the two triplet states smoothly dissociates to yield O((3)P) with little or no barrier. Single point calculations are consistent with the same phenomenon occurring for dibenzothiophene-S-oxide (DBTO). This provides an explanation for the inefficient unimolecular photochemical dissociation of O((3)P) from DBTO despite a phosphorescence energy below that of S-O dissociation, i.e., that S-O scission probably occurs from a spectroscopically unobserved triplet (T2) state.

Electro-oxidation of the dye azure B: kinetics, mechanism, and by-products.

PubMed

Olvera-Vargas, Hugo; Oturan, Nihal; Aravindakumar, C T; Paul, M M Sunil; Sharma, Virender K; Oturan, Mehmet A

2014-01-01

In this work, the electrochemical degradation of the dye azure B in aqueous solutions was studied by electrochemical advanced oxidation processes (EAOPs), electro-Fenton, and anodic oxidation processes, using Pt/carbon-felt and boron-doped diamond (BDD)/carbon-felt cells with H₂O₂ electrogeneration. The higher oxidation power of the electro-Fenton (EF) process using BDD anode was demonstrated. The oxidative degradation of azure B by the electrochemically generated hydroxyl radicals ((•)OH) follows a pseudo-first-order kinetics. The apparent rate constants of the oxidation of azure B by (•)OH were measured according to pseudo-first-order kinetic model. The absolute rate constant of azure B hydroxylation reaction was determined by competition kinetics method and found to be 1.19 × 10(9) M(-1) s(-1). It was found that the electrochemical degradation of the dye leads to the formation of aromatic by-products which are then oxidized to aliphatic carboxylic acids before their almost mineralization to CO₂ and inorganic ions (sulfate, nitrate, and ammonium). The evolution of the TOC removal and time course of short-chain carboxylic acids during treatment were also investigated.

Sensitive and Selective NH₃ Monitoring at Room Temperature Using ZnO Ceramic Nanofibers Decorated with Poly(styrene sulfonate).

PubMed

Andre, Rafaela S; Kwak, Dongwook; Dong, Qiuchen; Zhong, Wei; Correa, Daniel S; Mattoso, Luiz H C; Lei, Yu

2018-04-01

Ammonia (NH₃) gas is a prominent air pollutant that is frequently found in industrial and livestock production environments. Due to the importance in controlling pollution and protecting public health, the development of new platforms for sensing NH₃ at room temperature has attracted great attention. In this study, a sensitive NH₃ gas device with enhanced selectivity is developed based on zinc oxide nanofibers (ZnO NFs) decorated with poly(styrene sulfonate) (PSS) and operated at room temperature. ZnO NFs were prepared by electrospinning followed by calcination at 500 °C for 3 h. The electrospun ZnO NFs are characterized to evaluate the properties of the as-prepared sensing materials. The loading of PSS to prepare ZnO NFs/PSS composite is also optimized based on the best sensing performance. Under the optimal composition, ZnO NFs/PSS displays rapid, reversible, and sensitive response upon NH₃ exposure at room temperature. The device shows a dynamic linear range up to 100 ppm and a limit of detection of 3.22 ppm and enhanced selectivity toward NH₃ in synthetic air, against NO₂ and CO, compared to pure ZnO NFs. Additionally, a sensing mechanism is proposed to illustrate the sensing performance using ZnO NFs/PSS composite. Therefore, this study provides a simple methodology to design a sensitive platform for NH₃ monitoring at room temperature.

Enantioconvergent hydrolysis of racemic styrene oxide at high concentration by a pair of novel epoxide hydrolases into (R)-phenyl-1,2-ethanediol.

PubMed

Wang, Rui; Hu, Die; Zong, Xuncheng; Li, Jinping; Ding, Lei; Wu, Minchen; Li, Jianfang

2017-12-01

To prepare (R)-phenyl-1,2-ethanediol ((R)-PED) with high enantiomeric excess (ee p ) and yield from racemic styrene oxide (rac-SO) at high concentration by bi-enzymatic catalysis. The bi-enzymatic catalysis was designed for enantioconvergent hydrolysis of rac-SO by a pair of novel epoxide hydrolases (EHs), a Vigna radiata EH3 (VrEH3) and a variant (AuEH2 A250I ) of Aspergillus usamii EH2. The simultaneous addition mode of VrEH3 and AuEH2 A250I , exhibiting the highest average turnover frequency (aTOF) of 0.12 g h -1 g -1 , was selected, by which rac-SO (10 mM) was converted into (R)-PED with 92.6% ee p and 96.3% yield. Under the optimized reaction conditions: dry weight ratio 14:1 of VrEH3-expressing E. coli/vreh3 to AuEH2 A250I -expressing E. coli/Aueh2 A250I and reaction at 20 °C, rac-SO (10 mM) was completely hydrolyzed in 2.3 h, affording (R)-PED with 98% ee p . At the weight ratio 0.8:1 of rac-SO to two mixed dry cells, (R)-PED with 97.4% ee p and 98.7% yield was produced from 200 mM (24 mg/ml) rac-SO in 10.5 h. Enantioconvergent hydrolysis of rac-SO at high concentration catalyzed by both VrEH3 and AuEH2 A250I is an effective method for preparing (R)-PED with high ee p and yield.

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

NASA Astrophysics Data System (ADS)

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.

Formation of highly oxygenated low-volatility products from cresol oxidation

NASA Astrophysics Data System (ADS)

Schwantes, Rebecca H.; Schilling, Katherine A.; McVay, Renee C.; Lignell, Hanna; Coggon, Matthew M.; Zhang, Xuan; Wennberg, Paul O.; Seinfeld, John H.

2017-03-01

Hydroxyl radical (OH) oxidation of toluene produces ring-retaining products: cresol and benzaldehyde, and ring-opening products: bicyclic intermediate compounds and epoxides. Here, first- and later-generation OH oxidation products from cresol and benzaldehyde are identified in laboratory chamber experiments. For benzaldehyde, first-generation ring-retaining products are identified, but later-generation products are not detected. For cresol, low-volatility (saturation mass concentration, C* ˜ 3.5 × 104 - 7.7 × 10-3 µg m-3), first- and later-generation ring-retaining products are identified. Subsequent OH addition to the aromatic ring of o-cresol leads to compounds such as hydroxy, dihydroxy, and trihydroxy methyl benzoquinones and dihydroxy, trihydroxy, tetrahydroxy, and pentahydroxy toluenes. These products are detected in the gas phase by chemical ionization mass spectrometry (CIMS) and in the particle phase using offline direct analysis in real-time mass spectrometry (DART-MS). Our data suggest that the yield of trihydroxy toluene from dihydroxy toluene is substantial. While an exact yield cannot be reported as authentic standards are unavailable, we find that a yield for trihydroxy toluene from dihydroxy toluene of ˜ 0.7 (equal to the reported yield of dihydroxy toluene from o-cresol; Olariu et al., 2002) is consistent with experimental results for o-cresol oxidation under low-NO conditions. These results suggest that even though the cresol pathway accounts for only ˜ 20 % of the oxidation products of toluene, it is the source of a significant fraction (˜ 20-40 %) of toluene secondary organic aerosol (SOA) due to the formation of low-volatility products.

An investigation of oxidation products and SOA yields from OH + pesticide reactions

NASA Astrophysics Data System (ADS)

Murschell, T.; Friedman, B.; Link, M.; Farmer, D.

2016-12-01

Pesticides are used globally in agricultural and residential areas. After application and/or volatilization from a surface, these compounds can be transported over long distances in the atmosphere. However, their chemical fate, including oxidation and gas-particle partitioning in the atmosphere, is not well understood. We present gas and particle measurements of oxidation products from pesticide + OH reactions using a dynamic solution injection system coupled to an Oxidative Flow Reactor. Products were detected with a High Resolution Time of Flight Iodide Chemical Mass Spectrometer (HR-ToF-CIMS) and a Size Mobility Particle Scanner (SMPS). The OFR allows pesticides to react with variable OH radical exposures, ranging from the equivalent of one day to a full week of atmospheric oxidative aging. In this work, we explore pesticide oxidation products from reaction with OH and ozone, and compare those products to photolysis reactions. Pesticides of similar chemical structures were explored, including acetochlor / metolachlor and permethrin / cypermethrin, to explore mechanistic differences. We present chemical parameters including average product oxidation state, average oxygen to carbon ratio, and potential secondary organic aerosol formation for each of these compounds.

The production of oxidants in Europa's surface.

PubMed

Johnson, R E; Quickenden, T I; Cooper, P D; McKinley, A J; Freeman, C G

2003-01-01

The oxidants produced by radiolysis and photolysis in the icy surface of Europa may be necessary to sustain carbon-based biochemistry in Europa's putative subsurface ocean. Because the subduction of oxidants to the ocean presents considerable thermodynamic challenges, we examine the formation of oxygen and related species in Europa's surface ice with the goal of characterizing the chemical state of the irradiated material. Relevant spectral observations of Europa and the laboratory data on the production of oxygen and related species are first summarized. Since the laboratory data are incomplete, we examine the rate equations for formation of oxygen and its chemical precursors by radiolysis and photolysis. Measurements and simple rate equations are suggested that can be used to characterize the production of oxidants in Europa's surface material and the chemical environment produced by radiolysis. Possible precursor molecules and the role of radical trapping are examined. The possibility of oxygen reactions on grain surfaces in Europa's regolith is discussed, and the earlier estimates of the supply of O(2) to the atmosphere are increased.

Graphene oxide and H2 production from bioelectrochemical graphite oxidation.

PubMed

Lu, Lu; Zeng, Cuiping; Wang, Luda; Yin, Xiaobo; Jin, Song; Lu, Anhuai; Jason Ren, Zhiyong

2015-11-17

Graphene oxide (GO) is an emerging material for energy and environmental applications, but it has been primarily produced using chemical processes involving high energy consumption and hazardous chemicals. In this study, we reported a new bioelectrochemical method to produce GO from graphite under ambient conditions without chemical amendments, value-added organic compounds and high rate H2 were also produced. Compared with abiotic electrochemical electrolysis control, the microbial assisted graphite oxidation produced high rate of graphite oxide and graphene oxide (BEGO) sheets, CO2, and current at lower applied voltage. The resultant electrons are transferred to a biocathode, where H2 and organic compounds are produced by microbial reduction of protons and CO2, respectively, a process known as microbial electrosynthesis (MES). Pseudomonas is the dominant population on the anode, while abundant anaerobic solvent-producing bacteria Clostridium carboxidivorans is likely responsible for electrosynthesis on the cathode. Oxygen production through water electrolysis was not detected on the anode due to the presence of facultative and aerobic bacteria as O2 sinkers. This new method provides a sustainable route for producing graphene materials and renewable H2 at low cost, and it may stimulate a new area of research in MES.

Emission pattern of semi-volatile organic compounds from recycled styrenic polymers using headspace solid-phase microextraction gas chromatography-mass spectrometry.

PubMed

Vilaplana, Francisco; Martínez-Sanz, Marta; Ribes-Greus, Amparo; Karlsson, Sigbritt

2010-01-15

The emission of low molecular weight compounds from recycled high-impact polystyrene (HIPS) has been investigated using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). Four released target analytes (styrene, benzaldehyde, acetophenone, and 2-phenylpropanal) were selected for the optimisation of the HS-SPME sampling procedure, by analysing operating parameters such as type of SPME fibre (polarity and operating mechanism), particle size, extraction temperature and time. 26 different compounds were identified to be released at different temperatures from recycled HIPS, including residues of polymerisation, oxidated derivates of styrene, and additives. The type of SPME fibre employed in the sampling procedure affected the detection of emitted components. An adsorptive fibre such as carbowax/polydimethylsiloxane (CAR/PDMS fibre) offered good selectivity for both non-polar and polar volatile compounds at lower temperatures; higher temperatures result in interferences from less-volatile released compounds. An absorptive fibre as polydimethylsiloxane (PDMS) fibre is suitable for the detection of less-volatile non-polar molecules at higher temperatures. The nature and relative amount of the emitted compounds increased with higher exposure temperature and smaller polymeric particle size. HS-SPME proves to be a suitable technique for screening the emission of semi-volatile organic compounds (SVOCs) from polymeric materials; reliable quantification of the content of target analytes in recycled HIPS is however difficult due to the complex mass-transfer processes involved, matrix effects, and the difficulties in equilibrating the analytical system. 2009 Elsevier B.V. All rights reserved.

High Performance Graphene Oxide Based Rubber Composites

PubMed Central

Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

2013-01-01

In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications. PMID:23974435

ω-3 in meat products: benefits and effects on lipid oxidative stability.

PubMed

Bernardi, Daniela Miotto; Bertol, Teresinha Marisa; Pflanzer, Sérgio Bertelli; Sgarbieri, Valdemiro Carlos; Pollonio, Marise Aparecida Rodrigues

2016-06-01

Although ω-3 intake has been associated with numerous health benefits, its addition to certain food matrices, and in particular meat products, may involve various technological barriers influencing the final quality of the products. Lipid oxidation must be highlighted due to the modification of both the sensory characteristics and the shelf-life of meat products. In order to reduce the impact of chemical changes and promote oxidative stability, the use of natural antioxidants has gained ground owing to the health and safety advantages linked to its effectiveness at reducing lipid oxidation. Many natural compounds have also been successfully tested in animal feed, in order to protect the raw meat materials and reduce the risk of lipid oxidation in processed products. This review aims to address the challenges and advantages of the incorporation of ω-3 fatty acids in raw meat materials and processed meat products, and to describe the use of different compounds to enhance lipid oxidative stability. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Liquid-liquid phase separation in dilute solutions of poly(styrene sulfonate) with multivalent cations: Phase diagrams, chain morphology, and impact of temperature

NASA Astrophysics Data System (ADS)

Hansch, Markus; Hämisch, Benjamin; Schweins, Ralf; Prévost, Sylvain; Huber, Klaus

2018-01-01

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.

A photo-assisted microbial electrolysis cell for the exclusive biohydrogen production using a MoS2-coated p-type copper oxide

NASA Astrophysics Data System (ADS)

Jeon, Yongwon; Kim, Jun Hyun; Koo, Kyoungmin; Kim, Sunghyun

2018-01-01

A microbial electrolysis cell (MEC) has been regarded as an emerging new technology for the biohydrogen production from various organic substances, even from wastewater. One major problem is, however, that methane dominates produced gases in a long-term operation. Here we report that a photo-assisted MEC (PAMEC) is an efficient way to produce hydrogen with a p-type semiconductor cathode. When Cu2O coated with MoS2 as cocatalyst (MoS2/Cu2O) is employed, only hydrogen with essentially no methane and carbon dioxide was produced from acetate at -0.8 V bias under visible light illumination at a rate of 2.72 m3H2 m-3d-1. No appreciable performance degradation is observed over 50 days of operation. At lower bias voltage, methane and carbon dioxide begins to be produced. Energy efficiency based on input electricity and hydrogen yield are 225% and 3.4, respectively. This excellent feature of PAMEC is attributed to p-type semiconductor characteristics of Cu2O and proton reduction activity of MoS2. Electrons generated from acetate oxidation at the anode are photoexcited to the conduction band at the Cu2O acquiring enough reduction potential to reduce protons. The concept of PAMEC can be extended to wastewater treatment for the hydrogen production.

Kinetics of abiotic nitrous oxide production via oxidation of hydroxylamine by particulate metals in seawater

NASA Astrophysics Data System (ADS)

Cavazos, A. R.; Taillefert, M.; Glass, J. B.

2016-12-01

The oceans are a significant of nitrous oxide (N2O) to the atmosphere. Current models of global oceanic N2­O flux focus on microbial N2O cycling and often ignore abiotic reactions, such as the thermodynamically favorable oxidation of the nitrification intermediate hydroxylamine (NH2OH) by Mn(IV) or Fe(III). At circumneutral pH, NH2OH oxidation is more thermodynamically favorable via Mn(IV) than Fe(III) reduction. We characterized the kinetics of NH2OH oxidation in synthetic ocean water at pH 5.1-8.8 using microsensor electrodes to measure real-time N2O production. N2O production rates and yield were greater when NH2OH was oxidized by Mn(IV) than Fe(III). Accordingly, the reduction of Mn(IV) was first order with respect to NH2OH whereas the reduction of Fe(III) was zero order with respect to NH2OH. Interestingly, the order of the reaction with respect to Mn(IV) appears to be negative whereas the reaction is second order with respect to Fe(III). The inverse order with respect to Mn(IV) may be due to the aggregation of particles in seawater, which decreases their surface area and changes their reactivity. Finally, the reaction is first order with respect to protons with Fe(III) as the oxidant but zero order with Mn(IV). The stronger effect of the pH on the reaction with Fe(III) as the oxidant compared to Mn(IV) reflects the stoichiometry of these two reactions, as each mole of N2O produced by Fe(III) reduction consumes eight protons while each mole of N2O produced with Mn(IV) as the oxidant requires only four protons. Our data show that abiotic NH2OH oxidation by Mn(IV) or Fe(III) particles may represent a significant source of N2O in seawater. These findings suggest that abiotic N2O production in marine waters may be significant in areas of the oceans where particulate metals originating from aerosols, dust, or rivers may react with NH2OH released from ammonia-oxidizing microorganisms.

Bilirubin and its oxidation products damage brain white matter

PubMed Central

Lakovic, Katarina; Ai, Jinglu; D'Abbondanza, Josephine; Tariq, Asma; Sabri, Mohammed; Alarfaj, Abdullah K; Vasdev, Punarjot; Macdonald, Robert Loch

2014-01-01

Brain injury after intracerebral hemorrhage (ICH) occurs in cortex and white matter and may be mediated by blood breakdown products, including hemoglobin and heme. Effects of blood breakdown products, bilirubin and bilirubin oxidation products, have not been widely investigated in adult brain. Here, we first determined the effect of bilirubin and its oxidation products on the structure and function of white matter in vitro using brain slices. Subsequently, we determined whether these compounds have an effect on the structure and function of white matter in vivo. In all, 0.5 mmol/L bilirubin treatment significantly damaged both the function and the structure of myelinated axons but not the unmyelinated axons in brain slices. Toxicity of bilirubin in vitro was prevented by dimethyl sulfoxide. Bilirubin oxidation products (BOXes) may be responsible for the toxicity of bilirubin. In in vivo experiments, unmyelinated axons were found more susceptible to damage from bilirubin injection. These results suggest that unmyelinated axons may have a major role in white-matter damage in vivo. Since bilirubin and BOXes appear in a delayed manner after ICH, preventing their toxic effects may be worth investigating therapeutically. Dimethyl sulfoxide or its structurally related derivatives may have a potential therapeutic value at antagonizing axonal damage after hemorrhagic stroke. PMID:25160671

Regulation of adrenomedullin and nitric oxide production by periodontal bacteria.

PubMed

Hussain, Q A; McKay, I J; Gonzales-Marin, C; Allaker, R P

2015-10-01

In periodontitis the host response to bacterial challenge includes activity of the multifunctional molecules adrenomedullin (AM) and nitric oxide (NO). The aim of this study was to investigate the role of periodontal bacteria in regulating the production of these molecules from cultured cells. Regulation of AM and NO production from oral keratinocytes when challenged with culture supernatants from Aggregatibacter actinomycetemcomitans, Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Veillonella atypica, Streptococcus salivarius and Candida albicans was examined. AM and NO were measured in cell culture supernatants using an enzyme-linked immunosorbent assay and the nitrate/nitrite (NO metabolites) Griess assay respectively. Cellular production of AM and inducible NO synthase was also analysed in target cells by immunofluorescence and Western blot analysis. The inter-relationship of AM and NO production were further investigated with macrophages. A. actinomycetemcomitans and C. rectus induced maximal levels of both AM and NO after 6 and 48 h respectively from oral keratinocytes. AM production in macrophages was upregulated in response to the NO donor S-nitrosoglutathione and partially blocked by the inducible NO synthase inhibitor, N(ω) -Nitro-l-arginine methyl ester hydrochloride. Likewise, NO production was increased upon exposure to AM, while the AM receptor antagonist AM 22-52 reduced the release of NO. Pathogens associated with aggressive periodontitis, A. actinomycetemcomitans and C. rectus, were more effective than those associated with chronic periodontitis, P. gingivalis and Prev. intermedia, and commensals, S. salivarius and V. atypica, as regards the upregulation of AM and NO production from oral keratinocytes. Interaction between these molecules was also demonstrated with macrophages. Understanding the coordinated regulation of AM and NO production in response to periodontal bacteria may identify

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

USDA-ARS?s Scientific Manuscript database

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...

Identifying initial molecular targets of PDT: protein and lipid oxidation products

NASA Astrophysics Data System (ADS)

Oleinick, Nancy L.; Kim, Junhwan; Rodriguez, Myriam E.; Xue, Liang-yan; Kenney, Malcolm E.; Anderson, Vernon E.

2009-06-01

Photodynamic Therapy (PDT) generates singlet oxygen (1O2) which oxidizes biomolecules in the immediate vicinity of its formation. The phthalocyanine photosensitizer Pc 4 localizes to mitochondria and endoplasmic reticulum, and the primary targets of Pc 4-PDT are expected to be lipids and proteins of those membranes. The initial damage then causes apoptosis in cancer cells via the release of cytochrome c (Cyt-c) from mitochondria into the cytosol, followed by the activation of caspases. That damage also triggers the induction of autophagy, an attempt by the cells to eliminate damaged organelles, or when damage is too extensive, to promote cell death. Cyt-c is bound to the cytosolic side of the mitochondrial inner membrane through association with cardiolipin (CL), a phospholipid containing four unsaturated fatty acids and thus easily oxidized by 1O2 or by other oxidizing agents. Increasing evidence suggests that oxidation of CL loosens its association with Cyt-c, and that the peroxidase activity of Cyt-c can oxidize CL. In earlier studies of Cyt-c in homogeneous medium by MALDI-TOF-MS and LC-ESI-MS, we showed that 1O2 generated by Pc 4-PDT oxidized histidine, methionine, tryptophan, and unexpectedly phenylalanine but not tyrosine. Most of the oxidation products were known to be formed by other oxidizing agents, such as hydroxyl radical, superoxide radical anion, and peroxynitrite. However, two products of histidine were unique to 1O2 and may be useful for reporting the action of 1O2 in cells and tissues. These products, as well as CL oxidation products, have now been identified in liposomes and mitochondria after Pc 4-PDT. In mitochondria, the PDT dose-dependent oxidations can be related to specific changes in mitochondrial function, Bcl-2 photodamage, and Cyt-c release. Thus, the role of PDT-generated 1O2 in oxidizing Cyt-c and CL and the interplay between protein and lipid targets may be highly relevant to understanding one mechanism for cell killing by PDT.

A two-stage combined trickle bed reactor/biofilter for treatment of styrene/acetone vapor mixtures.

PubMed

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.

Birchwood biochar as partial carbon black replacement in styrene-butadiene rubber composites

USDA-ARS?s Scientific Manuscript database

Birchwood feedstock was used to make slow pyrolysis biochar that contained 89% carbon and < 2% ash. This biochar was blended with carbon black as filler for styrene-butadiene rubber. Composites made from blended fillers of 25/75 biochar/carbon black were equivalent to or superior to their 100% carbo...

S-nitrosothiols regulate nitric oxide production and storage in plants through the nitrogen assimilation pathway

PubMed Central

Frungillo, Lucas; Skelly, Michael J.; Loake, Gary J.; Spoel, Steven H.; Salgado, Ione

2014-01-01

Nitrogen assimilation plays a vital role in plant metabolism. Assimilation of nitrate, the primary source of nitrogen in soil, is linked to generation of the redox signal nitric oxide (NO). An important mechanism by which NO regulates plant development and stress responses is through S-nitrosylation, i.e. covalent attachment of NO to cysteines to form S-nitrosothiols (SNO). Despite the importance of nitrogen assimilation and NO signalling, it remains largely unknown how these pathways are interconnected. Here we show that SNO signalling suppresses both nitrate uptake and reduction by transporters and reductases, respectively, to fine-tune nitrate homeostasis. Moreover, NO derived from nitrate assimilation suppresses the redox enzyme S-nitrosoglutathione Reductase 1 (GSNOR1) by S-nitrosylation, preventing scavenging of S-nitrosoglutathione, a major cellular bio-reservoir of NO. Hence, our data demonstrates that (S)NO controls its own generation and scavenging by modulating nitrate assimilation and GSNOR1 activity. PMID:25384398

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

PubMed

Tisdale, Evgenia; Kennedy, Devin; Xu, Xiaodong; Wilkins, Charles

2014-01-15

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 CuBr2) than is the pentafluorostyrene component distribution. Copyright © 2013 Elsevier B.V. All rights reserved.

All-solution-processed PbS quantum dot solar modules.

PubMed

Jang, Jihoon; Shim, Hyung Cheoul; Ju, Yeonkyeong; Song, Jung Hoon; An, Hyejin; Yu, Jong-Su; Kwak, Sun-Woo; Lee, Taik-Min; Kim, Inyoung; Jeong, Sohee

2015-05-21

A rapid increase in power conversion efficiencies in colloidal quantum dot (QD) solar cells has been achieved recently with lead sulphide (PbS) QDs by adapting a heterojunction architecture, which consists of small-area devices associated with a vacuum-deposited buffer layer with metal electrodes. The preparation of QD solar modules by low-cost solution processes is required to further increase the power-to-cost ratio. Herein we demonstrate all-solution-processed flexible PbS QD solar modules with a layer-by-layer architecture comprising polyethylene terephthalate (PET) substrate/indium tin oxide (ITO)/titanium oxide (TiO2)/PbS QD/poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag, with an active area of up to 30 cm(2), exhibiting a power conversion efficiency (PCE) of 1.3% under AM 1.5 conditions (PCE of 2.2% for a 1 cm(2) unit cell). Our approach affords trade-offs between power and the active area of the photovoltaic devices, which results in a low-cost power source, and which is scalable to larger areas.

“Uncontrolled” Preparation of Disperse Poly(lactide)- block -poly(styrene)- block -poly(lactide) for Nanopatterning Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanderlaan, Marie E.; Hillmyer, Marc A.

We report the facile synthesis of well-defined ABA poly(lactide)-block-poly(styrene)-block-poly(lactide) (LSL) triblock copolymers having a disperse poly(styrene) midblock (Ð = 1.27–2.24). The direct synthesis of telechelic α,ω-hydroxypoly(styrene) (HO-PS-OH) midblocks was achieved using a commercially available difunctional free radical diazo initiator 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]. Poly(lactide) (PLA) end blocks were subsequently grown from HO-PS-OH macroinitiators via ring-opening transesterification polymerization of (±)-lactide using the most common and prevalent catalyst system available, tin(II) 2-ethylhexanoate. Fourteen LSL triblock copolymers with total molar masses Mn,total = 24–181 kg/mol and PLA volume fractions fPLA = 0.15–0.68 were synthesized and thoroughly characterized. The self-assembly of symmetric triblocks was analyzed in themore » bulk using small-angle X-ray scattering and in thin films using grazing incidence small-angle X-ray scattering and atomic force microscopy. We demonstrate both the bulk and thin film self-assembly of LSL disperse triblocks gave well-organized nanostructures with uniform domain sizes suitable for nanopatterning applications.« less

40 CFR 721.10574 - Alkylcarboxy polyester acrylate reaction products with mixed metal oxides (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... reaction products with mixed metal oxides (generic). 721.10574 Section 721.10574 Protection of Environment... reaction products with mixed metal oxides (generic). (a) Chemical substance and significant new uses... reaction products with mixed metal oxides (PMN P-09-48) is subject to reporting under this section for the...

40 CFR 721.10574 - Alkylcarboxy polyester acrylate reaction products with mixed metal oxides (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... reaction products with mixed metal oxides (generic). 721.10574 Section 721.10574 Protection of Environment... reaction products with mixed metal oxides (generic). (a) Chemical substance and significant new uses... reaction products with mixed metal oxides (PMN P-09-48) is subject to reporting under this section for the...

Studies toward the oxidative and reductive activation of C-S bonds in 2'-S-aryl-2'-thiouridine derivatives.

PubMed

Rayala, Ramanjaneyulu; Giuglio-Tonolo, Alain; Broggi, Julie; Terme, Thierry; Vanelle, Patrice; Theard, Patricia; Médebielle, Maurice; Wnuk, Stanislaw F

2016-04-21

Studies directed toward the oxidative and reductive desulfurization of readily available 2'- S -aryl-2'-thiouridine derivatives were investigated with the prospect to functionalize the C2'-position of nucleosides. The oxidative desulfurization-difluorination strategy was successful on 2-(arylthio)alkanoate surrogates, while extension of the combination of oxidants and fluoride sources was not an efficient fluorination protocol when applied to 2'- S -aryl-2'-thiouridine derivatives, resulting mainly in C5-halogenation of the pyrimidine ring and C2'-monofluorination without desulfurization. Cyclic voltammetry of 2'-arylsulfonyl-2'-deoxyuridines and their 2'-fluorinated analogues showed that cleavage of the arylsulfone moiety could occur, although at relatively high cathodic potentials. While reductive-desulfonylation of 2'-arylsulfonyl-2'-deoxyuridines with organic electron donors (OEDs) gave predominantly base-induced furan type products, chemical (OED) and electrochemical reductive-desulfonylation of the α-fluorosulfone derivatives yielded the 2'-deoxy-2'-fluorouridine and 2',3'-didehydro-2',3'-dideoxy-2'-fluorouridine derivatives. These results provided good evidence of the generation of a C2'-anion through carbon-sulfur bond cleavage, opening new horizons for the reductive-functionalization approaches in nucleosides.

Studies toward the oxidative and reductive activation of C-S bonds in 2'-S-aryl-2'-thiouridine derivatives

PubMed Central

Rayala, Ramanjaneyulu; Giuglio-Tonolo, Alain; Broggi, Julie; Terme, Thierry; Vanelle, Patrice; Theard, Patricia; Médebielle, Maurice; Wnuk, Stanislaw F.

2016-01-01

Studies directed toward the oxidative and reductive desulfurization of readily available 2'-S-aryl-2'-thiouridine derivatives were investigated with the prospect to functionalize the C2'-position of nucleosides. The oxidative desulfurization-difluorination strategy was successful on 2-(arylthio)alkanoate surrogates, while extension of the combination of oxidants and fluoride sources was not an efficient fluorination protocol when applied to 2'-S-aryl-2'-thiouridine derivatives, resulting mainly in C5-halogenation of the pyrimidine ring and C2'-monofluorination without desulfurization. Cyclic voltammetry of 2'-arylsulfonyl-2'-deoxyuridines and their 2'-fluorinated analogues showed that cleavage of the arylsulfone moiety could occur, although at relatively high cathodic potentials. While reductive-desulfonylation of 2'-arylsulfonyl-2'-deoxyuridines with organic electron donors (OEDs) gave predominantly base-induced furan type products, chemical (OED) and electrochemical reductive-desulfonylation of the α-fluorosulfone derivatives yielded the 2'-deoxy-2'-fluorouridine and 2',3'-didehydro-2',3'-dideoxy-2'-fluorouridine derivatives. These results provided good evidence of the generation of a C2'-anion through carbon-sulfur bond cleavage, opening new horizons for the reductive-functionalization approaches in nucleosides. PMID:27019535

Production of petroleum bitumen by oxidation of heavy oil residue with sulfur

NASA Astrophysics Data System (ADS)

Tileuberdi, Ye.; Akkazyn, Ye. A.; Ongarbayev, Ye. K.; Imanbayev, Ye. I.; Mansurov, Z. A.

2018-03-01

In this paper production of bitumen adding elemental sulfur at oxidation of oil residue are investigated. The objects of research were distilled residue of Karazhanbas crude oil and elemental sulfur. These oil residue characterized by a low output of easy fractions and the high content of tar-asphaltene substances, therefore is the most comprehensible feedstock for producing bitumen. The sulfur is one of the oil product collected in oil extraction regions. Oxidation process of hydrocarbons carried out at temperatures from 180 up to 210 °С without addition of sulfur and with the addition of sulfur (5-10 wt. %) for 4 hours. At 200 °С oxidation of hydrocarbons with 5, 7 and 10 wt.% sulfur within 3-4 h allows receiving paving bitumen on the mark BND 200/300, BND 130/200, BN 90/130 and BN 70/30. Physical and mechanical characteristics of oxidation products with the addition of 5-7 wt. % sulfur corresponds to grade of paving bitumen BND 40/60. At the given temperature oxidized for 2.5-3 h, addition of 10 wt. % sulfur gave the products of oxidation describing on parameters of construction grades of bitumen (BN 90/10).

Modeling SOA production from the oxidation of intermediate volatility alkanes

NASA Astrophysics Data System (ADS)

Aumont, B.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J.; Madronich, S.

2012-12-01

Secondary Organic Aerosols (SOA) production and ageing is a multigenerational oxidation process involving the formation of successive organic compounds with higher oxidation degree and lower vapour pressure. This process was investigated using the explicit oxidation model GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere). Results for the C8-C24 n-alkane series show the expected trends, i.e. (i) SOA yield grows with the carbon backbone of the parent hydrocarbon, (ii) SOA yields decreases with the decreasing pre-existing organic aerosol concentration, (iii) the number of generations required to describe SOA production increases when the pre-existing organic aerosol concentration decreases. Most SOA contributors were found to be not oxidized enough to be categorized as highly oxygenated organic aerosols (OOA) but reduced enough to be categorized as hydrocarbon like organic aerosols (HOA). Branched alkanes are more prone to fragment in the early stage of the oxidation than their corresponding linear analogues. Fragmentation is expected to alter both the yield and the mean oxidation state of the SOA. Here, GECKO-A is applied to generate highly detailed oxidation schemes for various series of branched and cyclised alkanes. Branching and cyclisation effects on SOA yields and oxidation states will be examined.

Complementary sample preparation strategies for analysis of cereal β-glucan oxidation products by UPLC-MS/MS

NASA Astrophysics Data System (ADS)

Boulos, Samy; Nyström, Laura

2017-11-01

��-attack on glucose units irrespective of glycosidic linkage and neighborhood. The method was demonstrated to be 1) sufficiently sensitive to allow for the analysis of oxidation products also from a mild ascorbate-driven Fenton reaction, and 2) to be specific for cereal β-glucan even in the presence of other co-oxidized polysaccharides. This opens doors to applications in food processing to assess potential oxidations and provides the detailed structural basis to understand the effect oxidized functional groups have on β-glucan’s health promoting and technological properties.

Poly(Acrylic Acid-b-Styrene) Amphiphilic Multiblock Copolymers as Building Blocks for the Assembly of Discrete Nanoparticles

PubMed Central

Greene, Anna C.; Zhu, Jiahua; Pochan, Darrin J.; Jia, Xinqiao; Kiick, Kristi L.

2011-01-01

In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by 1H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)9), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)9 (Mn = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)9 was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10-4 mg/mL. The (PAA-PS)9 multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules. PMID:21552373

Graphene oxide and H2 production from bioelectrochemical graphite oxidation

PubMed Central

Lu, Lu; Zeng, Cuiping; Wang, Luda; Yin, Xiaobo; Jin, Song; Lu, Anhuai; Jason Ren, Zhiyong

2015-01-01

Graphene oxide (GO) is an emerging material for energy and environmental applications, but it has been primarily produced using chemical processes involving high energy consumption and hazardous chemicals. In this study, we reported a new bioelectrochemical method to produce GO from graphite under ambient conditions without chemical amendments, value-added organic compounds and high rate H2 were also produced. Compared with abiotic electrochemical electrolysis control, the microbial assisted graphite oxidation produced high rate of graphite oxide and graphene oxide (BEGO) sheets, CO2, and current at lower applied voltage. The resultant electrons are transferred to a biocathode, where H2 and organic compounds are produced by microbial reduction of protons and CO2, respectively, a process known as microbial electrosynthesis (MES). Pseudomonas is the dominant population on the anode, while abundant anaerobic solvent-producing bacteria Clostridium carboxidivorans is likely responsible for electrosynthesis on the cathode. Oxygen production through water electrolysis was not detected on the anode due to the presence of facultative and aerobic bacteria as O2 sinkers. This new method provides a sustainable route for producing graphene materials and renewable H2 at low cost, and it may stimulate a new area of research in MES. PMID:26573014

Scalable Production Method for Graphene Oxide Water Vapor Separation Membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fifield, Leonard S.; Shin, Yongsoon; Liu, Wei

ABSTRACT Membranes for selective water vapor separation were assembled from graphene oxide suspension using techniques compatible with high volume industrial production. The large-diameter graphene oxide flake suspensions were synthesized from graphite materials via relatively efficient chemical oxidation steps with attention paid to maintaining flake size and achieving high graphene oxide concentrations. Graphene oxide membranes produced using scalable casting methods exhibited water vapor flux and water/nitrogen selectivity performance meeting or exceeding that of membranes produced using vacuum-assisted laboratory techniques. (PNNL-SA-117497)

Spectroscopic Analyses of the Biofuels-Critical Phytochemical Coniferyl Alcohol and Its Enzyme-Catalyzed Oxidation Products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Achyuthan, Komandoor; Adams, Paul; Simmons, Blake

2011-07-13

Lignin composition (monolignol types of coniferyl, sinapyl or p-coumaryl alcohol) is causally related to biomass recalcitrance. We describe multiwavelength (220, 228, 240, 250, 260, 290, 295, 300, 310 or 320 nm) absorption spectroscopy of coniferyl alcohol and its laccase- or peroxidase-catalyzed products during real time kinetic, pseudo-kinetic and endpoint analyses, in optical turn on or turn off modes, under acidic or basic conditions. Reactions in microwell plates and 100 mu L volumes demonstrated assay miniaturization and high throughput screening capabilities. Bathochromic and hypsochromic shifts along with hyperchromicity or hypochromicity accompanied enzymatic oxidations by laccase or peroxidase. The limits of detectionmore » and quantitation of coniferyl alcohol averaged 2.4 and 7.1 mu M respectively, with linear trend lines over 3 to 4 orders of magnitude. Coniferyl alcohol oxidation was evident within 10 minutes or with 0.01 mu g/mL laccase and 2 minutes or 0.001 mu g/mL peroxidase. Detection limit improved to 1.0 mu M coniferyl alcohol with Km of 978.7 +/- 150.7 mu M when examined at 260 nm following 30 minutes oxidation with 1.0 mu g/mL laccase. Our assays utilized the intrinsic spectroscopic properties of coniferyl alcohol or its oxidation products for enabling detection, without requiring chemical synthesis or modification of the substrate or product(s). These studies facilitate lignin compositional analyses and augment pretreatment strategies for reducing biomass recalcitrance.« less

Comparison of nitrogen removal rates and nitrous oxide production from enriched anaerobic ammonium oxidizing bacteria in suspended and attached growth reactors.

PubMed

Panwivia, Supaporn; Sirvithayapakorn, Sanya; Wantawin, Chalermraj; Noophan, Pongsak Lek; Munakata-Marr, Junko

2014-01-01

Attached growth-systems for the anaerobic ammonium oxidation (anammox) process have been postulated for implementation in the field. However, information about the anammox process in attached growth-systems is limited. This study compared nitrogen removal rates and nitrous oxide (N2O) production of enriched anammox cultures in both suspended and attached growth sequencing batch reactors (SBRs). Suspended growth reactors (SBR-S) and attached growth reactors using polystyrene sponge as a medium (SBR-A) were used in these experiments. After inoculation with an enriched anammox culture, significant nitrogen removals of ammonium (NH4 (+)) and nitrite (NO2 (-)) were observed under NH4 (+):NO2 (-) ratios ranging from 1:1 to 1:2 in both types of SBRs. The specific rates of total nitrogen removal in SBR-S and SBR-A were 0.52 mg N/mg VSS-d and 0.44 mg N/mg VSS-d, respectively, at an NH4 (+):NO2 (-) ratio of 1:2. N2O production by the enriched anammox culture in both SBR-S and SBR-A was significantly higher at NH4 (+):NO2 (-) ratio of 1:2 than at NH4 (+):NO2 (-) ratios of 1:1 and 1:1.32. In addition, N2O production was higher at a pH of 6.8 than at pH 7.3, 7.8, and 8.3 in both SBR-S and SBR-A. The results of this investigation demonstrate that the anammox process may avoid N2O emission by maintaining an NH4 (+):NO2 (-) ratio of less than 1:2 and pH higher than 6.8.

Nitrous oxide production by nitrification and denitrification in the Eastern Tropical South Pacific oxygen minimum zone

NASA Astrophysics Data System (ADS)

Ji, Qixing; Babbin, Andrew R.; Jayakumar, Amal; Oleynik, Sergey; Ward, Bess B.

2015-12-01

The Eastern Tropical South Pacific oxygen minimum zone (ETSP-OMZ) is a site of intense nitrous oxide (N2O) flux to the atmosphere. This flux results from production of N2O by nitrification and denitrification, but the contribution of the two processes is unknown. The rates of these pathways and their distributions were measured directly using 15N tracers. The highest N2O production rates occurred at the depth of peak N2O concentrations at the oxic-anoxic interface above the oxygen deficient zone (ODZ) because slightly oxygenated waters allowed (1) N2O production from both nitrification and denitrification and (2) higher nitrous oxide production yields from nitrification. Within the ODZ proper (i.e., anoxia), the only source of N2O was denitrification (i.e., nitrite and nitrate reduction), the rates of which were reflected in the abundance of nirS genes (encoding nitrite reductase). Overall, denitrification was the dominant pathway contributing the N2O production in the ETSP-OMZ.

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

NASA Astrophysics Data System (ADS)

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.

Oxidation of trimethoprim by ferrate(VI): kinetics, products, and antibacterial activity.

PubMed

Anquandah, George A K; Sharma, Virender K; Knight, D Andrew; Batchu, Sudha Rani; Gardinali, Piero R

2011-12-15

Kinetics, stoichiometry, and products of the oxidation of trimethoprim (TMP), one of the most commonly detected antibacterial agents in surface waters and municipal wastewaters, by ferrate(VI) (Fe(VI)) were determined. The pH dependent second-order rate constants of the reactions of Fe(VI) with TMP were examined using acid-base properties of Fe(VI) and TMP. The kinetics of reactions of diaminopyrimidine (DAP) and trimethoxytoluene (TMT) with Fe(VI) were also determined to understand the reactivity of Fe(VI) with TMP. Oxidation products of the reactions of Fe(VI) with TMP and DAP were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Reaction pathways of oxidation of TMP by Fe(VI) are proposed to demonstrate the cleavage of the TMP molecule to ultimately result in 3,4,5,-trimethoxybenzaldehyde and 2,4-dinitropyrimidine as among the final identified products. The oxidized products mixture exhibited no antibacterial activity against E. coli after complete consumption of TMP. Removal of TMP in the secondary effluent by Fe(VI) was achieved.

Surface Science and the Advancement of Direct Olefin Epoxidation A Perspective on the Article, ‘‘Partial Oxidation of Higher Olefins on Ag(111) and Ag(110): Conversion of Styrene to Styrene Oxide, Benzene, and Benzoic Acid’’, by Andreas Klust and Robert J. Madix.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barteau, Mark A.

2006-10-04