N-Doped TiO₂-Coated Ceramic Membrane for Carbamazepine Degradation in Different Water Qualities.

Science.gov (United States)

Luster, Enbal; Avisar, Dror; Horovitz, Inna; Lozzi, Luca; Baker, Mark A; Grilli, Rossana; Mamane, Hadas

2017-07-31

The photocatalytic degradation of the model pollutant carbamazepine (CBZ) was investigated under simulated solar irradiation with an N-doped TiO₂-coated Al₂O₃ photocatalytic membrane, using different water types. The photocatalytic membrane combines photocatalysis and membrane filtration in a single step. The impact of each individual constituent such as acidity, alkalinity, dissolved organic matter (DOM), divalent cations (Mg 2+ and Ca 2+ ), and Cl - on the degradation of CBZ was examined. CBZ in water was efficiently degraded by an N-doped TiO₂-coated Al₂O₃ membrane. However, elements added to the water, which simulate the constituents of natural water, had an impact on the CBZ degradation. Water alkalinity inhibited CBZ degradation mostly due to increase in pH while radical scavenging by carbonate was more dominant at higher values (>200 mg/L as CaCO₃). A negative effect of Ca 2+ addition on photocatalytic degradation was found only in combination with phosphate buffer, probably caused by deposition of CaHPO₄ or CaHPO₄·2H₂O on the catalyst surface. The presence of Cl - and Mg 2+ ions had no effect on CBZ degradation. DOM significantly inhibited CBZ degradation for all tested background organic compounds. The photocatalytic activity of N-doped TiO₂-coated Al₂O₃ membranes gradually decreased after continuous use; however, it was successfully regenerated by 0.1% HCl chemical cleaning. Nevertheless, dissolution of metals like Al and Ti should be monitored following acid cleaning.

A review of proton exchange membrane water electrolysis on degradation mechanisms and mitigation strategies

Science.gov (United States)

Feng, Qi; Yuan, Xiao-Zi; Liu, Gaoyang; Wei, Bing; Zhang, Zhen; Li, Hui; Wang, Haijiang

2017-10-01

Proton exchange membrane water electrolysis (PEMWE) is an advanced and effective solution to the primary energy storage technologies. A better understanding of performance and durability of PEMWE is critical for the engineers and researchers to further advance this technology for its market penetration, and for the manufacturers of PEM water electrolyzers to implement quality control procedures for the production line or on-site process monitoring/diagnosis. This paper reviews the published works on performance degradations and mitigation strategies for PEMWE. Sources of degradation for individual components are introduced. With degradation causes discussed and degradation mechanisms examined, the review emphasizes on feasible strategies to mitigate the components degradation. To avoid lengthy real lifetime degradation tests and their high costs, the importance of accelerated stress tests and protocols is highlighted for various components. In the end, R&D directions are proposed to move the PEMWE technology forward to become a key element in future energy scenarios.

On the use of supported ceria membranes for oxyfuel process/syngas production

DEFF Research Database (Denmark)

Lobera, M.P.; Serra, J.M.; Foghmoes, Søren Preben Vagn

2011-01-01

Ceramic oxygen transport membranes (OTMs) enable selective oxygen separation from air at high temperatures. Among several potential applications for OTMs, the use in (1) oxygen production for oxyfuel power plants and (2) the integration in high-temperature catalytic membrane reactors for alkane...... upgrading through selective oxidative reactions are of special interest. Nevertheless, these applications involve the direct contact of the membrane surface with carbon-rich atmospheres. Most state-of-the-art permeable membranes are based on perovskites, which are prone to carbonation under operation in CO2......-rich environments and/or decomposition in reducing gas environments. The oxygen flux through supported thin film membranes of Ce0.9Gd0.1O1.95−δ (CGO) with 2 mol.% of cobalt was measured for oxygen separation in oxyfuel processes and in syngas production and degradation was compared to perovskite...

DIDS prevents ischemic membrane degradation in cultured hippocampal neurons by inhibiting matrix metalloproteinase release.

Directory of Open Access Journals (Sweden)

Matthew E Pamenter

Full Text Available During stroke, cells in the infarct core exhibit rapid failure of their permeability barriers, which releases ions and inflammatory molecules that are deleterious to nearby tissue (the penumbra. Plasma membrane degradation is key to penumbral spread and is mediated by matrix metalloproteinases (MMPs, which are released via vesicular exocytosis into the extracellular fluid in response to stress. DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid preserves membrane integrity in neurons challenged with an in vitro ischemic penumbral mimic (ischemic solution: IS and we asked whether this action was mediated via inhibition of MMP activity. In cultured murine hippocampal neurons challenged with IS, intracellular proMMP-2 and -9 expression increased 4-10 fold and extracellular latent and active MMP isoform expression increased 2-22 fold. MMP-mediated extracellular gelatinolytic activity increased ∼20-50 fold, causing detachment of 32.1±4.5% of cells from the matrix and extensive plasma membrane degradation (>60% of cells took up vital dyes and >60% of plasma membranes were fragmented or blebbed. DIDS abolished cellular detachment and membrane degradation in neurons and the pathology-induced extracellular expression of latent and active MMPs. DIDS similarly inhibited extracellular MMP expression and cellular detachment induced by the pro-apoptotic agent staurosporine or the general proteinase agonist 4-aminophenylmercuric acetate (APMA. Conversely, DIDS-treatment did not impair stress-induced intracellular proMMP production, nor the intracellular cleavage of proMMP-2 to the active form, suggesting DIDS interferes with the vesicular extrusion of MMPs rather than directly inhibiting proteinase expression or activation. In support of this hypothesis, an antagonist of the V-type vesicular ATPase also inhibited extracellular MMP expression to a similar degree as DIDS. In addition, in a proteinase-independent model of vesicular exocytosis, DIDS

Degradation and contamination of perfluorinated sulfonic acid membrane due to swelling-dehydration cycles

DEFF Research Database (Denmark)

Andersen, Shuang Ma; Morgen, Per; Skou, Eivind Morten

Formation of sulfonic anhydride S-O-S (from the condensation of sulfonic acids) was known one of the important degradation mechanisms [i] for Nafion membrane under hydrothermal aging condition, which is especially critical for hydrogen fuel cells. Similar mechanism would also have be desirable...... to the membrane degradation in direct methanol fuel cells (DMFCs), where liquid water has direct contact with the electrolyte. An ex-situ experiment was established with swelling-dehydration cycles on the membrane. However, formation of sulfonic anhydride was not detected during the entire treatment; instead...

N-Doped TiO2-Coated Ceramic Membrane for Carbamazepine Degradation in Different Water Qualities

Science.gov (United States)

Luster, Enbal; Avisar, Dror; Horovitz, Inna; Lozzi, Luca; Baker, Mark A.; Grilli, Rossana; Mamane, Hadas

2017-01-01

The photocatalytic degradation of the model pollutant carbamazepine (CBZ) was investigated under simulated solar irradiation with an N-doped TiO2-coated Al2O3 photocatalytic membrane, using different water types. The photocatalytic membrane combines photocatalysis and membrane filtration in a single step. The impact of each individual constituent such as acidity, alkalinity, dissolved organic matter (DOM), divalent cations (Mg2+ and Ca2+), and Cl− on the degradation of CBZ was examined. CBZ in water was efficiently degraded by an N-doped TiO2-coated Al2O3 membrane. However, elements added to the water, which simulate the constituents of natural water, had an impact on the CBZ degradation. Water alkalinity inhibited CBZ degradation mostly due to increase in pH while radical scavenging by carbonate was more dominant at higher values (>200 mg/L as CaCO3). A negative effect of Ca2+ addition on photocatalytic degradation was found only in combination with phosphate buffer, probably caused by deposition of CaHPO4 or CaHPO4·2H2O on the catalyst surface. The presence of Cl− and Mg2+ ions had no effect on CBZ degradation. DOM significantly inhibited CBZ degradation for all tested background organic compounds. The photocatalytic activity of N-doped TiO2-coated Al2O3 membranes gradually decreased after continuous use; however, it was successfully regenerated by 0.1% HCl chemical cleaning. Nevertheless, dissolution of metals like Al and Ti should be monitored following acid cleaning. PMID:28758982

Photocatalytic Degradation of Oil using Polyvinylidene Fluoride/Titanium Dioxide Composite Membrane for Oily Wastewater Treatment

Directory of Open Access Journals (Sweden)

Rusli Ummi Nadiah

2016-01-01

Full Text Available Production of industrial wastewater is increasing as the oil and gas industry grows rapidly over the years. The constituents in the industrial wastewater such as organic and inorganic matters, dispersed and lubricant oil and metals which have high toxicity become the major concern to the environment and ecosystem. There are many technologies are being used for oil removal from industrial wastewater. However, there are still needs to find an effective technology to treat oily wastewater before in can be discharge safely to the environment. Membrane technology is an attractive separation technology to treat oily wastewater. The aim of this study is to fabricate polyvinylidene/titanium dioxide (PVDF/TiO2 composite membrane with further treatment using hot pressed method to enhance the adhesion between TiO2 with the membrane surfaces. In this study the structural and physical properties of fabricated membrane were conducted using X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR respectively. The photocatalytic degradation of oil was measured using UV-Vis Spectroscopy. The FTIR results confirmed that, hot pressed PVDF/TiO2 membrane TiO2 was successfully deposited onto PVDF membranes surface and XRD results shows that the XRD pattern of PVDF//TiO2 found that the crystalline structure was remained unchanged after hot pressed. Clear water was obtained after synthetic oily wastewater was exposed to visible light for at least 6 hours. In conclusion, PVDF/TiO2 composite membrane can be a potential candidate to degrade oil in oily wastewater and suggested to possess an excellent performance if perform simultaneously with membrane separation process.

Oxidative degradation of acid doped polybenzimidazole membranes and fuel cell durability in the presence of ferrous ions

DEFF Research Database (Denmark)

Liao, Jianhui; Yang, Jingshuai; Li, Qingfeng

2013-01-01

Phosphoric acid doped polybenzimidazole membranes have been explored as proton exchange membranes for high temperature polymer electrolyte membrane fuel cells. Long-term durability of the membrane is of critical concern and has been evaluated by accelerated degradation tests under Fenton conditions...... of the polymer. Fuel cell durability tests with contaminations of ferrous ions did show considerable performance degradation, however, primarily due to the catalyst deterioration rather than the membrane degradation........ In this study effects of phosphoric acid and ferrous ions were investigated by measurements of the weight loss, intrinsic viscosity and size exclusion chromatography (SEC) of the polymer membranes. Ferrous ions resulted in, as expected, catalytic formation of peroxide radicals and hence the accelerated polymer...

Performance and dye-degrading bacteria isolation of a hybrid membrane process

Energy Technology Data Exchange (ETDEWEB)

You, Sheng-Jie, E-mail: sjyou@cycu.edu.tw [Department of Bioenvironmental Engineering and R and D Center for Membrane Technology, Chung Yuan Christian University, No. 200, Rd. Chung-Pei, Chungli 320, Taiwan (China); Teng, Jun-Yu, E-mail: nickprometheus@yahoo.com.tw [Department of Civil Engineering, Chung Yuan Christian University, Chungli 320, Taiwan (China)

2009-12-15

Textile dyeing wastewater contains harmful compounds, which are toxic to both marine organisms and human beings if it discharged into an aquatic environmental without suitable treatment. In this study, the wastewater containing the azo dye, Reactive Black 5 (RB5), was partially treated in an anaerobic sequencing batch reactor which was further treated either in an aerobic membrane bioreactors (AOMBR) or in combined aerobic membrane bioreactor/reverse osmosis (AOMBR/RO) process. The results showed that in the anaerobic sequencing batch reactor the RB5 dye was degraded to form aromatic amine intermediate metabolites, which were further mineralized in the AOMBR. It was also observed that although all effluents from the AOMBR and AOMBR/RO processes met the Taiwan EPA's effluent criteria, irrespective of which membranes were used in the aerobic tank, the effluent from the AOMBR/RO process met the criteria for reuse for toilet flushing, landscaping, irrigation, and cooling water purposes, where as the AOMBR effluent only met the criteria for cooling water due to incomplete color removal. Five anaerobic high dye-degrading bacteria were isolated, which were identified to be the same species of Lactococcus lactis by 16S rRNA sequencing. The L. lactis showed complete degradation of RB5 and further studies showed that it can also able to degrade Reactive Red 120 and Reactive Yellow 84 efficiently within 6 h.

Performance and dye-degrading bacteria isolation of a hybrid membrane process

International Nuclear Information System (INIS)

You, Sheng-Jie; Teng, Jun-Yu

2009-01-01

Textile dyeing wastewater contains harmful compounds, which are toxic to both marine organisms and human beings if it discharged into an aquatic environmental without suitable treatment. In this study, the wastewater containing the azo dye, Reactive Black 5 (RB5), was partially treated in an anaerobic sequencing batch reactor which was further treated either in an aerobic membrane bioreactors (AOMBR) or in combined aerobic membrane bioreactor/reverse osmosis (AOMBR/RO) process. The results showed that in the anaerobic sequencing batch reactor the RB5 dye was degraded to form aromatic amine intermediate metabolites, which were further mineralized in the AOMBR. It was also observed that although all effluents from the AOMBR and AOMBR/RO processes met the Taiwan EPA's effluent criteria, irrespective of which membranes were used in the aerobic tank, the effluent from the AOMBR/RO process met the criteria for reuse for toilet flushing, landscaping, irrigation, and cooling water purposes, where as the AOMBR effluent only met the criteria for cooling water due to incomplete color removal. Five anaerobic high dye-degrading bacteria were isolated, which were identified to be the same species of Lactococcus lactis by 16S rRNA sequencing. The L. lactis showed complete degradation of RB5 and further studies showed that it can also able to degrade Reactive Red 120 and Reactive Yellow 84 efficiently within 6 h.

Performance Degradation Tests of Phosphoric Acid Doped Polybenzimidazole Membrane Based High Temperature Polymer Electrolyte Membrane Fuel Cells

DEFF Research Database (Denmark)

Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

2015-01-01

Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2 and meth...

A novel catalytic ceramic membrane fabricated with CuMn2O4 particles for emerging UV absorbers degradation from aqueous and membrane fouling elimination.

Science.gov (United States)

Guo, Yang; Song, Zilong; Xu, Bingbing; Li, Yanning; Qi, Fei; Croue, Jean-Philippe; Yuan, Donghai

2018-02-15

A novel catalytic ceramic membrane (CM) for improving ozonation and filtration performance was fabricated by surface coating CuMn 2 O 4 particles on a tubular CM. The degradation of ultraviolet (UV) absorbers, reduction of toxicity, elimination of membrane fouling and catalytic mechanism were investigated. The characterization results suggested the particles were well-fixed on membrane surface. The modified membrane showed improved benzophenone-3 removal performance (from 28% to 34%), detoxification (EC 50 as 12.77%) and the stability of catalytic activity. In the degradation performance of model UV absorbers, the developed membrane significantly decreased the UV254 and DOC values in effluent. Compared with a virgin CM, this CM ozonation increased water flux as 29.9% by in-situ degrade effluent organic matters. The CuMn 2 O 4 modified membrane enhanced the ozone self-decompose to generate O 2 - and initiated the chain reaction of ozone decomposition, and subsequently reacted with molecule ozone to produce OH. Additionally, CM was able to promote the interaction between ozone and catalyst/organic chemicals to form H 2 O 2 that promoted the formation of OH. This catalytic ceramic membrane combining with ozonation showed potential applications in emerging pollutant degradation and membrane fouling elimination, and acted as a novel ternary technology for wastewater treatment and water reuse. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced enzymatic cellulose degradation by cellobiohydrolases via product removal

DEFF Research Database (Denmark)

Ahmadi Gavlighi, Hassan; Meyer, Anne S.; Mikkelsen, Jørn Dalgaard

2013-01-01

Product inhibition by cellobiose decreases the rate of enzymatic cellulose degradation. The optimal reaction conditions for two Emericella (Aspergillus) nidulans-derived cellobiohydrolases I and II produced in Pichia pastoris were identified as CBHI: 52 °C, pH 4.5–6.5, and CBHII: 46 °C, pH 4.......8. The optimum in a mixture of the two was 50 °C, pH 4.9. An almost fourfold increase in enzymatic hydrolysis yield was achieved with intermittent product removal of cellobiose with membrane filtration (2 kDa cut-off): The conversion of cotton cellulose after 72 h was ~19 % by weight, whereas the conversion...

In-vitro Degradation Behaviour of Irradiated Bacterial Cellulose Membrane

International Nuclear Information System (INIS)

Darwis, D.; Khusniya, T.; Hardiningsih, L.; Nurlidar, F.; Winarno, H.

2012-01-01

Bacterial cellulose membrane synthesized by Acetobacter xylinum in coconut water medium has potential application for Guided bone Regeneration. However, this membrane may not meet some application requirements due to its low biodegradation properties. In this paper, incorporation of gamma irradiation into the membrane is a developed strategy to increase its biodegradability properties. The in-vitro degradation study in synthetic body fluid (SBF) of the irradiated membrane has been analyzed during periods of 6 months by means of weight loss, mechanical properties and scanning electron microscopy observation compared to that the un-irradiated one. The result showed that weight loss of irradiated membrane with 25 kGy and 50 kGy and immersed in SBF solution for 6 months reached 18% and 25% respectively. While un-irradiated membrane did not give significant weight loss. Tensile strength of membranes decreases with increasing of irradiation dose and further decreases in tensile strength is observed when irradiated membrane was followed by immersion in SBF solution. Microscope electron image of cellulose membranes shows that un-irradiated bacterial cellulose membrane consists of dense ultrafine fibril network structures, while irradiation result in cleavage of fibrils network of cellulose. The fibrils network become loosely after irradiated membrane immersed in SBF solution due to released of small molecular weight carbohydrates formed during by irradiation from the structure (author)

Effect of perfluorosulfonic acid membrane equivalent weight on degradation under accelerated stress conditions

International Nuclear Information System (INIS)

Rodgers, Marianne P.; Pearman, Benjamin P.; Mohajeri, Nahid; Bonville, Leonard J.; Slattery, Darlene K.

2013-01-01

The equivalent weight of proton exchange membranes has a large effect on their properties and can impact performance and durability in hydrogen fuel cells. For example, increasing the EW increases the crystallinity of perfluorosulfonic acid membranes, while water content and glass transition temperature decrease. The length of the sulfonic acid side chain also impacts membrane properties. Perfluorosulfonic acid membranes with shorter sulfonic acid side chains, though they exhibit similar gas permeability, have been shown to have higher crystallinity, higher glass transition temperature, slightly lower water content, and lower proton conductivity than membranes with longer sulfonic acid side chains for a given EW. Although many reports have investigated cell performance for membranes as a function of low EW and side chains length, their impact on cell durability is not well understood. Because side chain attack by radicals formed during fuel cell operation is a major source of membrane degradation, it is reasonable to hypothesize that membranes with lower EW and, therefore, more sulfonic acid side chains, would have lower durability. This study evaluates membrane degradation for cells containing PFSA membranes with 750 EW, 950 EW, and 1100 EW. The 750 EW membrane contained short sulfonic acid side-chains while the 950 EW and 1100 EW membranes were Nafion ® -based with long sulfonic acid side-chains. Membranes were tested in fuel cells for 100 h under open circuit voltage, at 90 °C and 30% relative humidity. Diagnostic tests conducted on the cells included hydrogen crossover, fluoride emission, catalyst electrochemical surface area, posttest membrane scanning electron microscopy/transmission electron microscopy evaluation, and defect identification in membranes. The 950 EW cell had the highest decay metrics including fluoride emission, voltage decay, loss in ECA, and loss in cell performance. In all cases, the 1100 EW cell showed the lowest degradation. This has

Chemical degradation of proton conducting perflurosulfonic acid ionomer membranes studied by solid-state nuclear magnetic resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Ghassemzadeh, L. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Institut fuer Physikalische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Marrony, M. [European Institute for Energy Research, Emmy-Noether-Strasse 11, D-76131 Karlsruhe (Germany); Barrera, R. [Edison, Via Giorgio La Pira, 2, I-10028 Trofarello (Italy); Kreuer, K.D.; Maier, J. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Mueller, K. [Institut fuer Physikalische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)

2009-01-15

The degradation of two different types of perfluorinated polymer membranes, Nafion and Hyflon Ion, has been examined by solid-state {sup 19}F and {sup 13}C NMR spectroscopy. This spectroscopic technique is demonstrated to be a valuable tool for the study of the membrane structure and its alterations after in situ degradation in a fuel cell. The structural changes in different parts of the polymers are clearly distinguished, which provides unique insight into details of the degradation processes. The experimental NMR spectra prove that degradation mostly takes place within the polymer side chains, as reflected by the intensity losses of NMR signals associated with SO{sub 3}H, CF{sub 3}, OCF{sub 2} and CF groups. The integral degree of degradation is found to decrease with increasing membrane thickness while for a given thickness, Hyflon Ion appears to degrade less than Nafion. (author)

Free-standing hierarchical α-MnO2@CuO membrane for catalytic filtration degradation of organic pollutants.

Science.gov (United States)

Luo, Xinsheng; Liang, Heng; Qu, Fangshu; Ding, An; Cheng, Xiaoxiang; Tang, Chuyang Y; Li, Guibai

2018-06-01

Catalytic membrane, due to its compact reactor assembling, high catalytic performance as well as low energy consumption, has proved to be more attractive for wastewater treatment. In this work, a free-standing α-MnO 2 @CuO membrane with hierarchical nanostructures was prepared and evaluated as the catalytic membrane to generate radicals from peroxymonosulfate (PMS) for the oxidative degradation of organic dyes in aqueous solution. Benefiting from the high mass transport efficiency and the hierarchical nanostructures, a superior catalytic activity of the membrane was observed for organic dyes degradation. As a typical organic dye, more than 99% of methylene blue (MB) was degraded within 0.23 s using dead-end filtration cell. The effects of flow rate, PMS concentration and buffer solution on MB degradation were further investigated. Besides MB, the catalytic membrane also showed excellent performance for the removal of other dyes, such as congo red, methyl orange, rhodamine B, acid chrome blue K and malachite green. Moreover, the mechanism study indicated that OH and SO 4 - generated from the interaction between PMS and Mn/Cu species with different oxidation states mainly accounted for the dyes degradation. The catalytic filtration process using α-MnO 2 @CuO catalytic membrane could provide a novel method for wastewater purification with high efficiency and low energy consumption. Copyright © 2018 Elsevier Ltd. All rights reserved.

Degradation of surface-labeled hepatoma membrane polypeptides: effect of inhibitors

International Nuclear Information System (INIS)

Hare, J.F.; Huston, M.

1984-01-01

When their membrane proteins were labeled with 125I by lactoperoxidase, dividing hepatoma cells lost radioactivity to the medium in a biphasic manner (T1/2 . 16-26 h, greater than 40 h). Lysosomotropic weak bases, chloroquine, and NH4Cl inhibited the rapid phase by 59%. More than 50% of the radioactivity which accumulates in the media from dividing cells during the first 4 h after labeling was trichloroacetic acid-soluble, and was identified as iodotyrosine. Iodotyrosine release from labeled membrane proteins was 60-71% inhibited by lysosomotropic agents chloroquine and NH4Cl as well as the sodium-proton ionophore, monensin. The inhibitory effect of NH4Cl and monensin was reversible. Inhibitors of microtubule and microfilament function and transglutamination had no effect on release of iodotyrosine to the medium, but trypsin-like protease inhibitors, p-aminobenzamidine, tosyl-L-lysine/chloromethylketone, and phenylmethylsulfonyl fluoride, as well as the cathepsin B inhibitor, leupeptin, inhibited by 21-24%. Iodotyrosine release showed a biphasic Arrhenius plot with an activation energy of 17 kcal/mol above but 27 kcal/mol below 20 degrees C. These results indicate that cell membrane polypeptides require a temperature-limiting event as well as passage through an ion-sensitive compartment prior to their complete degradation to constituent amino acids. In contrast to other lysosomal-mediated events, however, iodinated membrane proteins of dividing cells are degraded in a manner insensitive to agents which disrupt the cytoskeleton

Degradation of organic pollutants by an integrated photo-Fenton-like catalysis/immersed membrane separation system

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yuanyuan, E-mail: jiedeng05@sina.com [School of Environment, Guang Xi University, Nanning 530004 (China); School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Xiong, Ya [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Tang, Yankui; Wang, Yinghui [School of Environment, Guang Xi University, Nanning 530004 (China)

2013-01-15

Highlights: ► The photo-Fenton-like reaction and membrane separation was coupled. ► FeVO{sub 4} was used as catalyst in the PFM reactor. ► Dynamics simulation would direct the actual application of the reactor. -- Abstract: To resolve the continuously reuse problem of fine catalysts, a new reactor was investigated by coupling the heterogeneous photo-Fenton-like oxidation with membrane separation. The reactor consisted of a Xe lamp, a submerged membrane module and FeVO{sub 4} as catalyst with high activity. Results showed that the catalyst was successfully left in the reactor. It was proved by the kinetics study of membrane fouling that the avoidless membrane fouling was brought mainly by surface cake, at catalyst concentration of 4 g/L, it accounted for more than 90% of the total resistance. The kinetics study of catalytic degradation of AO II under sub-critical flux showed the optimal concentration of catalyst was 0.5 g/L and under this concentration the membrane fouling was negligible. For a residence time of 60 min, the degradation efficiency of AO II reached more than 99% and the chemical oxygen demand (COD) removal efficiency was as high as 91%. The model of continuous stirred tank reactor could predict well for the degradation which was consistent with hydrodynamics study. Moreover, the PFM reactor shows a long-term behavior with both membrane and catalyst in it and merits consideration for scaled-up trials.

Membrane complexes of Syntrophomonas wolfei involved in syntrophic butyrate degradation and hydrogen formation

Directory of Open Access Journals (Sweden)

Bryan Regis Crable

2016-11-01

Full Text Available Syntrophic butyrate metabolism involves the thermodynamically unfavorable production of hydrogen and/or formate from the high potential electron donor, butyryl-CoA. Such redox reactions can occur only with energy input by a process called reverse electron transfer. Previous studies have demonstrated that hydrogen production from butyrate requires the presence of a proton gradient, but the biochemical machinery involved has not been clearly elucidated. In this study, the gene and enzyme systems involved in reverse electron transfer by Syntrophomonas wolfei were investigated using proteomic and gene expression approaches. S. wolfei was grown in coculture with Methanospirillum hungatei or Dehalococcoides mccartyi under conditions requiring reverse electron transfer and compared to both axenic S. wolfei cultures and cocultures grown in conditions that do not require reverse electron transfer. Blue native gel analysis of membranes solubilized from syntrophically grown cells revealed the presence of a membrane-bound hydrogenase, Hyd2, which exhibited hydrogenase activity during in gel assays. Bands containing a putative iron-sulfur (FeS oxidoreductase were detected in membranes of crotonate-grown and butyrate grown S. wolfei cells. The genes for the corresponding hydrogenase subunits, hyd2ABC, were differentially expressed at higher levels during syntrophic butyrate growth when compared to growth on crotonate. The expression of the FeS oxidoreductase gene increased when S. wolfei was grown with M. hungatei. Additional membrane-associated proteins detected included FoF1 ATP synthase subunits and several membrane transporters that may aid syntrophic growth. Furthermore, syntrophic butyrate metabolism can proceed exclusively by interspecies hydrogen transfer, as demonstrated by growth with D. mccartyi, which is unable to use formate. These results argue for the importance of Hyd2 and FeS oxidoreductase in reverse electron transfer during syntrophic

Photocatalytic reusable membranes for the effective degradation of tartrazine with a solar photoreactor.

Science.gov (United States)

Aoudjit, L; Martins, P M; Madjene, F; Petrovykh, D Y; Lanceros-Mendez, S

2018-02-15

Recalcitrant dyes present in effluents constitute a major environmental concern due to their hazardous properties that may cause deleterious effects on aquatic organisms. Tartrazine is a widely-used dye, and it is known to be resistant to biological and chemical degradation processes and by its carcinogenic and mutagenic nature. This study presents the use of TiO 2 (P25) nanoparticles immobilized into a poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) membrane to assess the photocatalytic degradation of this dye in a solar photoreactor. The nanocomposite morphological properties were analyzed, confirming an interconnected porous microstructure and the homogeneous distribution of the TiO 2 nanoparticles within the membrane pores. It is shown that the nanocomposite with 8wt% TiO 2 exhibits a remarkable sunlight photocatalytic activity over five hours, with 78% of the pollutant being degraded. It was also demonstrated that the degradation follows pseudo-first-order kinetics model at low initial tartrazine concentration. Finally, the effective reusability of the produced nanocomposite was also assessed. Copyright © 2017 Elsevier B.V. All rights reserved.

Nuclear liquid wastes treatment: study of the reverse osmosis membranes degradation under γ irradiation

International Nuclear Information System (INIS)

Combernoux, Nicolas

2015-01-01

The treatment of nuclear liquid wastes by reverse osmosis (RO) involved issues of the water radiolysis and the membrane ageing due to γ irradiation effects. Membrane performances (permeability, strontium and cesium retention) were assessed after γ irradiation. Irradiation was carried out with an external 60 Co source in different conditions that simulated real used of the process (dose from 0.1 to 1 MGy, dose rate of 0.5 and 5 kGy.h -1 , with or without oxygen or water). Several analytical methods were performed to evaluate irradiation effects (ATR-FTIR, XPS, gas production, water soluble species released from the membrane). The methodology developed led to relevant information due to an innovative analytical protocol. Membrane performances started dropping between 0.2 and 0.5 MGy with oxygen and water (dose rate 0.5 kGy.h -1 ). This shift was linked to chains scissions inside the membrane active layer. The membrane degradation was weaker without oxygen or water or at high dose rate (5 kGy.h -1 ). Results showed that each analysis comforted each other. Membrane performances were also evaluated with three different types of liquid effluents, representing radioactive effluents from a post-disaster situation (groundwater type), disaster situation (seawater) or process water. Experiments were carried out at lab and pilot scales. Results indicated that the treatment of each effluent was possible by RO with an adequate choice of membrane and operating parameters. Finally, the time to reach an integrated dose threshold for the membrane in real conditions was estimated with the RABBI software: a dozen of days in the case of disaster situation to several years in the two other cases. (author) [fr

Removal and Degradation Pathways of Sulfamethoxazole Present in Synthetic Municipal Wastewater via an Anaerobic Membrane Bioreactor

KAUST Repository

Sanchez Huerta, Claudia

2016-05-01

The current global water crisis in addition to continues contamination of natural water bodies with harmful organic micropollutants (OMPs) have driven the development of new water treatment technologies that allow the efficient removal of such compounds. Among a long list of OMPs, antibiotics are considered as top priority pollutants to be treated due to their great resistance to biological treatments and their potential to develop bacterial resistance. Different approaches, such as membrane-based and advance oxidation processes have been proposed to alleviate or minimize antibiotics discharge into aquatic environments. However most of these processes are costly and generate either matrices with high concentration of OMPs or intermediate products with potentially greater toxicity or persistence. Therefore, this thesis proposes the study of an anaerobic membrane bioreactor (AnMBR) for the treatment of synthetic municipal wastewater containing sulfamethoxazole (SMX), a world widely used antibiotic. Besides the general evaluation of AnMBR performance in the COD removal and biogas production, this research mainly focuses on the SMX removal and its degradation pathway. Thus 5 SMX quantification was performed through solid phase extraction-liquid chromatography/mass spectrometry and the identification of its transformation products (TPs) was assessed by gas chromatography/mass spectrometry technique. The results achieved showed that, working under optimal conditions (35°C, pH 7 and ORP around -380 to -420 mV) and after a biomass adaptation period (maintaining 0.85 VSS/TSS ratio), the AnMBR process provided over 95% COD removal and 95-98% SMX removal, while allowing stable biogas composition and methane production (≈130 mL CH4/g CODremoved). Kinetic analysis through a batch test showed that after 24 h of biological reaction, AnMBR process achieved around 94% SMX removal, indicating a first order kinetic reaction with K= 0.119, which highlights the high degradation

Determination of impurities and degradation products from veterinary medicinal products by HPLC method

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Elena Gabriela Oltean

2014-06-01

Full Text Available The organic or inorganic impurities in the veterinary medicinal product can derive from starting materials, manufacturing process, incomplete purification, inappropriate storage. The acceptable levels of impurities in pharmaceuticals are estimated by comparison with standard solutions, according to the appropriate monographs. Forced degradation studies determine the stability of the method of dosage for the active compounds and for the entire finished product under excessive accelerated degradation conditions. They also provide information on degradation pathways and selectivity of analytical methods applied. The information provided by the degradation studies on the active compound and finished pharmaceutical product should demonstrate the specificity of the analytical method regarding impurities. Forced degradation studies should demonstrate that the impurities and degradation products generated do not interfere with the active compound. The current forced degradation methods consist of acid hydrolysis, basic hydrolysis, oxidation, exposure of the medicinal product to temperature and light. HPLC methods are an integral analytical instrument for the analysis of the medicinal product. The HPLC method should be able to separate, detect and quantify various specific degradation products that can appear after manufacture or storage of the medicinal product, as well as new elements appearing after synthesis. FDA and ICH guidelines recommend the enclosure of the results, including the chromatograms specific to the forced degradation-subjected medicinal product, in the documentation for marketing authorization. Using HPLC methods in forced degradation studies on medicinal products provides relevant information on the method of determination for the formulation of the medicinal product, synthesis product, packaging methods and storage.

Reduction in energy consumption of electrochemical pesticide degradation through combination with membrane filtration

DEFF Research Database (Denmark)

Madsen, Henrik Tækker; Søgaard, Erik Gydesen; Muff, Jens

2015-01-01

A significant challenge for large-scale use of electrochemical oxidation (EO) is high energy consumption, and for EO to become accepted as a standard technique, the amount of energy consumed in the process must be reduced. In this study, it was investigated how the energy consumption of EO could...... be lowered by combining the process with membrane filtration, in a setup where EO was applied to the membrane retentate stream. Use of two types of membranes, a nanofiltration (NF) and a reverse osmosis (RO) membrane, was investigated, and to provide realistic estimates on the energy consumption...... of the treatment, natural groundwater spiked with the pesticide residue 2,6-dichlorobenzamide (BAM) was used as matrix in the experiments. To understand the effect of the membranes on the energy consumption, their effect on the EO degradation efficiency was also determined. The results showed that membranes...

Recent advances on membranes and membrane reactors for hydrogen production

NARCIS (Netherlands)

Gallucci, F.; Fernandez Gesalaga, E.; Corengia, P.; Sint Annaland, van M.

2013-01-01

Membranes and membrane reactors for pure hydrogen production are widely investigated not only because of the important application areas of hydrogen, but especially because mechanically and chemically stable membranes with high perm-selectivity towards hydrogen are available and are continuously

Degradation of endothelial basement membrane by human breast cancer cell lines

International Nuclear Information System (INIS)

Yee, C.; Shiu, R.P.

1986-01-01

During metastasis, it is believed that tumor cells destroy the basement membrane (BM) of blood vessels in order to disseminate through the circulatory system. By radioactively labeling the extracellular matrix produced by primary endothelial cells in vitro, the ability of human breast cancer cells to degrade BM components was studied. We found that T-47D, a human breast cancer line, was able to degrade significant amounts of [35S]methionine-labeled and [3H]proline-labeled BM, but not 35SO4-labeled BM. Six other tumor cell lines of human breast origin were assayed in the same manner and were found to degrade BM to varying degrees. Several non-tumor cell lines tested showed relatively little degrading activity. The use of serum-free medium greatly enhanced degradation of the BM by tumor cells, suggesting a role for naturally occurring enzyme inhibitors in the serum. Direct cell contact with the BM was required for BM degradation, suggesting that the active enzymes are cell associated. The addition of hormones implicated in the etiology of breast cancer did not significantly alter the ability of T-47D cells to degrade the BM. The use of this assay affords future studies on the mechanism of invasion and metastasis of human breast cancer

Unraveling micro- and nanoscale degradation processes during operation of high-temperature polymer-electrolyte-membrane fuel cells

Science.gov (United States)

Hengge, K.; Heinzl, C.; Perchthaler, M.; Varley, D.; Lochner, T.; Scheu, C.

2017-10-01

The work in hand presents an electron microscopy based in-depth study of micro- and nanoscale degradation processes that take place during the operation of high-temperature polymer-electrolyte-membrane fuel cells (HT-PEMFCs). Carbon supported Pt particles were used as cathodic catalyst material and the bimetallic, carbon supported Pt/Ru system was applied as anode. As membrane, cross-linked polybenzimidazole was used. Scanning electron microscopy analysis of cross-sections of as-prepared and long-term operated membrane-electrode-assemblies revealed insight into micrometer scale degradation processes: operation-caused catalyst redistribution and thinning of the membrane and electrodes. Transmission electron microscopy investigations were performed to unravel the nanometer scale phenomena: a band of Pt and Pt/Ru nanoparticles was detected in the membrane adjacent to the cathode catalyst layer. Quantification of the elemental composition of several individual nanoparticles and the overall band area revealed that they stem from both anode and cathode catalyst layers. The results presented do not demonstrate any catastrophic failure but rather intermediate states during fuel cell operation and indications to proceed with targeted HT-PEMFC optimization.

Potentialities of a Membrane Reactor with Laccase Grafted Membranes for the Enzymatic Degradation of Phenolic Compounds in Water

Directory of Open Access Journals (Sweden)

Vorleak Chea

2014-10-01

Full Text Available This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR. The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L−1, consumption increased with flux (up to 7.9 × 103 mg·h−1·m−2 at 128 L·h−1·m−2, whereas at the highest substrate concentration (500 mg·L−1, it was shown that the reaction was limited by the oxygen content.

Degradation of Reactive Black 5 dye using anaerobic/aerobic membrane bioreactor (MBR) and photochemical membrane reactor

International Nuclear Information System (INIS)

You, Sheng-Jie; Damodar, Rahul A.; Hou, Sheng-Chon

2010-01-01

Three different types of advance treatment methods were evaluated for the degradation of Reactive Black 5 (RB5). The performance of two stage anaerobic SBR-aerobic MBR, anaerobic MBR with immobilized and suspended biocells and an integrated membrane photocatalytic reactor (MPR) using slurry UV/TiO 2 system were investigated. The results suggest that, nearly 99.9% color removal and 80-95% organic COD and TOC removal can be achieved using different reactor systems. Considering the Taiwan EPA effluent standard discharge criteria for COD/TOC, the degree of treatment achieved by combining the anaerobic-aerobic system was found to be acceptable. Anew, Bacilluscereus, high color removal bacterium was isolated from Anaerobic SBR. Furthermore, when this immobilized into PVA-calcium alginate pellets, and suspended in the anaerobic MBR was able to achieve high removal efficiencies, similar to the suspended biocells system. However, the immobilized cell Anaerobic MBR was found to be more advantageous, due to lower fouling rates in the membrane unit. Results from slurry type MPR system showed that this system was capable of mineralizing RB5 dyes with faster degradation rate as compared to other systems. The reactor was also able to separate the catalyst effectively and perform efficiently without much loss of catalyst activity.

Degradation analysis and modeling of reinforced catalyst coated membranes operated under OCV conditions

Energy Technology Data Exchange (ETDEWEB)

Kundu, Sumit; Fowler, Michael W.; Simon, Leonardo C. [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario (Canada); Abouatallah, Rami; Beydokhti, Natasha [Hydrogenics Corporation, 5985 McLaughlin Road, Mississauga, Ontario (Canada)

2008-09-01

This paper studies the degradation of Gore trademark PRIMEA {sup registered} series 5510 catalyst coated membranes with an ePTFE reinforcement layer under open circuit voltage conditions at 90 C, 75% RH, and no backpressure. Scanning electron microscopy (SEM) imaging of cross-sections revealed extensive cathode-side ionomer degradation and the presence of a platinum band. Cumulative fluoride release measurements show more fluoride exiting with the cathode effluent. Furthermore, both anode and cathode cumulative fluoride release plateau after long degradation times. Open circuit voltage was also monitored and the degradation rate was found to decrease after a long duration. It is proposed that all fluoride species are generated from the cathode-side ionomer degradation process and that the fluoride then diffuses to the anode and cathode channels. Further, once the cathode-side ionomer is consumed the degradation reaction slows as the ''degradation front'' passes through the inert reinforcement layer. This process was modeled using a semi-empirical transient model and compared to experimental results. (author)

Functional elastic hydrogel as recyclable membrane for the adsorption and degradation of methylene blue.

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Song Bao

Full Text Available Developing the application of high-strength hydrogels has gained much attention in the fields of medical, pharmacy, and pollutant removal due to their versatility and stimulus-responsive properties. In this presentation, a high-strength freestanding elastic hydrogel membrane was constructed by clay nanosheets, N, N-dimethylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid for adsorption of methylene blue and heavy metal ions. The maximum values of elongation and Young's modulus for 0.5% AMPSNa hydrogel were 1901% and 949.4 kPa, respectively, much higher than those of traditional hydrogels. The adsorptions were confirmed to follow pseudo-second kinetic equation and Langmuir isotherm model fits the data well. The maximum adsorption capacity of hydrogel towards methylene blue was 434.8 mg g(-1. The hydrogel also exhibited higher separation selectivity to Pb(2+ than Cu(2+. The methylene blue adsorbed onto the hydrogel membrane can be photocatalytically degraded by Fenton agent and the hydrogel membrane could be recycled at least five times without obvious loss in mechanical properties. In conclusion, this presentation demonstrates a convenient strategy to prepare tough and elastic clay nanocomposite hydrogel, which can not only be applied as recyclable membrane for the photocatalytic degradation of organic dye, but also for the recovery of valuables.

Research of the degradation products of chitosan's angiogenic function

International Nuclear Information System (INIS)

Wang Jianyun; Chen Yuanwei; Ding Yulong; Shi Guoqi; Wan Changxiu

2008-01-01

Angiogenesis is of great importance in tissue engineering and has gained large attention in the past decade. But how it will be influenced by the biodegradable materials, especially their degradation products, remains unknown. Chitosan (CS) is a kind of naturally occurred polysaccharide which can be degraded in physiological environment. In order to gain some knowledge of the influences of CS degradation products on angiogenesis, the interaction of vascular endothelial cells with the degradation products was investigated in the present study. The CS degradation products were prepared by keeping CS sample in physiological saline aseptically at 37 deg. C for 120 days. Endothelial cells were co-cultured with the degradation products and the angiogenic cell behaviors, including cell proliferation, migration and tube-like structure (TLS) formation, were tested by MTT assay, cell migration quantification method (CMQM), and tube-like structure quantification method (TLSQM) respectively. Furthermore, mRNA expressions of vascular endothelial growth factor (VEGF) and matrix metallo proteinase (MMP-2) were determined by real-time reverse transcriptional polymerase chain reaction (RT-PCR). Physiological saline served as a negative control. As the results showed, the degradation products obtained from 20th to 60th day significantly inhibited the proliferation, migration, and TLS formation of endothelial cells. However, degradation products of the first 14 days and the last 30 days were found to be proangiogenic. At the molecular level, the initial results indicated that the mRNA expressions of VEGF and MMP-2 were increased by the degradation products of 7th day, but were decreased by the ones of 60th day. According to all the results, it could be concluded that the angiogenic behaviors of endothelial cells at both cellular and molecular level could be significantly stimulated or suppressed by the degradation products of CS and the influences are quite time-dependent

A membrane stirrer for product recovery and substrate feeding.

Science.gov (United States)

Femmer, T; Carstensen, F; Wessling, M

2015-02-01

During fermentation processes, in situ product recovery (ISPR) using submerged membranes allows a continuous operation mode with effective product removal. Continuous recovery reduces product inhibition and organisms in the reactor are not exposed to changing reaction conditions. For an effective in situ product removal, submerged membrane systems should have a sufficient large membrane area and an anti-fouling concept integrated in a compact device for the limited space in a lab-scale bioreactor. We present a new membrane stirrer with integrated filtration membranes on the impeller blades as well as an integrated gassing concept in an all-in-one device. The stirrer is fabricated by rapid prototyping and is equipped with a commercial micromesh membrane. Filtration performance is tested using a yeast cell suspension with different stirring speeds and aeration fluxes. We reduce membrane fouling by backflushing through the membrane with the product stream. © 2014 Wiley Periodicals, Inc.

Influence of radiolytic degradation products from organic phase

International Nuclear Information System (INIS)

Azevedo, H.L.P. de.

1980-01-01

The influence of primary and secondary degradation products from TBP - dodecane on zirconium extraction is studied. The presence of radiolytical degradation at organic phase, in systems of initial concentration of HNO 3 1 and 4M, and absorbed γ radiation doses from 0,5 to 4,5 Wh/l, lead to an increase of zirconium extraction, being the HDBP the main product of degradation responsable by this effect. The influence of secondary degradation products is significative in systems of HNO 3 1M initial concentration. The formation of precipitator in extractions of Zr in HNO 3 1M with irradiated TBP-dodecane was observed. (M.C.K.) [pt

Multienzyme Immobilized Polymeric Membrane Reactor for the Transformation of a Lignin Model Compound

Directory of Open Access Journals (Sweden)

Rupam Sarma

2018-04-01

Full Text Available We have developed an integrated, multienzyme functionalized membrane reactor for bioconversion of a lignin model compound involving enzymatic catalysis. The membrane bioreactors were fabricated through the layer-by-layer assembly approach to immobilize three different enzymes (glucose oxidase, peroxidase and laccase into pH-responsive membranes. This novel membrane reactor couples the in situ generation of hydrogen peroxide (by glucose oxidase to oxidative conversion of a lignin model compound, guaiacylglycerol-β-guaiacyl ether (GGE. Preliminary investigation of the efficacy of these functional membranes towards GGE degradation is demonstrated under convective flow mode. Over 90% of the initial feed could be degraded with the multienzyme immobilized membranes at a residence time of approximately 22 s. GGE conversion product analysis revealed the formation of oligomeric oxidation products upon reaction with peroxidase, which may be a potential hazard to membrane bioreactors. These oxidation products could further be degraded by laccase enzymes in the multienzymatic membranes, explaining the potential of multi enzyme membrane reactors. The multienzyme incorporated membrane reactors were active for more than 30 days of storage time at 4 °C. During this time span, repetitive use of the membrane reactor was demonstrated involving 5–6 h of operation time for each cycle. The membrane reactor displayed encouraging performance, losing only 12% of its initial activity after multiple cycles of operation.

Characterization of the thermolysis products of Nafion membrane: A potential source of perfluorinated compounds in the environment

Science.gov (United States)

Feng, Mingbao; Qu, Ruijuan; Wei, Zhongbo; Wang, Liansheng; Sun, Ping; Wang, Zunyao

2015-05-01

The thermal decomposition of Nafion N117 membrane, a typical perfluorosulfonic acid membrane that is widely used in various chemical technologies, was investigated in this study. Structural identification of thermolysis products in water and methanol was performed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). The fluoride release was studied using an ion-chromatography system, and the membrane thermal stability was characterized by thermogravimetric analysis. Notably, several types of perfluorinated compounds (PFCs) including perfluorocarboxylic acids were detected and identified. Based on these data, a thermolysis mechanism was proposed involving cleavage of both the polymer backbone and its side chains by attack of radical species. This is the first systematic report on the thermolysis products of Nafion by simulating its high-temperature operation and disposal process via incineration. The results of this study indicate that Nafion is a potential environmental source of PFCs, which have attracted growing interest and concern in recent years. Additionally, this study provides an analytical justification of the LC/ESI-MS/MS method for characterizing the degradation products of polymer electrolyte membranes. These identifications can substantially facilitate an understanding of their decomposition mechanisms and offer insight into the proper utilization and effective management on these membranes.

The tissue-specific Rep8/UBXD6 tethers p97 to the endoplasmic reticulum membrane for degradation of misfolded proteins.

Directory of Open Access Journals (Sweden)

Louise Madsen

Full Text Available The protein known as p97 or VCP in mammals and Cdc48 in yeast is a versatile ATPase complex involved in several biological functions including membrane fusion, protein folding, and activation of membrane-bound transcription factors. In addition, p97 plays a central role in degradation of misfolded secretory proteins via the ER-associated degradation pathway. This functional diversity of p97 depends on its association with various cofactors, and to further our understanding of p97 function it is important that these cofactors are identified and analyzed. Here, we isolate and characterize the human protein named Rep8 or Ubxd6 as a new cofactor of p97. Mouse Rep8 is highly tissue-specific and abundant in gonads. In testes, Rep8 is expressed in post-meiotic round spermatids, whereas in ovaries Rep8 is expressed in granulosa cells. Rep8 associates directly with p97 via its UBX domain. We show that Rep8 is a transmembrane protein that localizes to the ER membrane with its UBX domain facing the cytoplasm. Knock-down of Rep8 expression in human cells leads to a decreased association of p97 with the ER membrane and concomitantly a retarded degradation of misfolded ER-derived proteasome substrates. Thus, Rep8 tethers p97 to the ER membrane for efficient ER-associated degradation.

Vitamin C degradation products and pathways in the human lens.

Science.gov (United States)

Nemet, Ina; Monnier, Vincent M

2011-10-28

Vitamin C and its degradation products participate in chemical modifications of proteins in vivo through non-enzymatic glycation (Maillard reaction) and formation of different products called advanced glycation end products. Vitamin C levels are particularly high in selected tissues, such as lens, brain and adrenal gland, and its degradation products can inflict substantial protein damage via formation of advanced glycation end products. However, the pathways of in vivo vitamin C degradation are poorly understood. Here we have determined the levels of vitamin C oxidation and degradation products dehydroascorbic acid, 2,3-diketogulonic acid, 3-deoxythreosone, xylosone, and threosone in the human lens using o-phenylenediamine to trap both free and protein-bound adducts. In the protein-free fraction and water-soluble proteins (WSP), all five listed degradation products were identified. Dehydroascorbic acid, 2,3-diketogulonic acid, and 3-deoxythreosone were the major products in the protein-free fraction, whereas in the WSP, 3-deoxythreosone was the most abundant measured dicarbonyl. In addition, 3-deoxythreosone in WSP showed positive linear correlation with age (p degradation product bound to human lens proteins provides in vivo evidence for the non-oxidative pathway of dehydroascorbate degradation into erythrulose as a major pathway for vitamin C degradation in vivo.

Track membranes, production, properties, applications

International Nuclear Information System (INIS)

Oganesjan, Yu.Ts.

1994-01-01

The problems of producing track membranes on heavy ion beams of the Flerov Laboratory are considered. The parameters of the running accelerators and equipment for the irradiation of polymer foils are presented. The process of production of track membranes based on different polymeric materials and various applications of the membranes are described. Special attention is given to the principally new applications and devices developed at the Laboratory. This report presents the results obtained by a big group of scientists and engineers working in the field of elaboration, investigation and application of track membranes (author). 21 refs, 20 figs, 1 tab

An Integrated Membrane Process for Butenes Production

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Leonardo Melone

2016-11-01

Full Text Available Iso-butene is an important material for the production of chemicals and polymers. It can take part in various chemical reactions, such as hydrogenation, oxidation and other additions owing to the presence of a reactive double bond. It is usually obtained as a by-product of a petroleum refinery, by Fluidized Catalytic Cracking (FCC of naphtha or gas-oil. However, an interesting alternative to iso-butene production is n-butane dehydroisomerization, which allows the direct conversion of n-butane via dehydrogenation and successive isomerization. In this work, a simulation analysis of an integrated membrane system is proposed for the production and recovery of butenes. The dehydroisomerization of n-butane to iso-butene takes place in a membrane reactor where the hydrogen is removed from the reaction side with a Pd/Ag alloys membrane. Afterwards, the retentate and permeate post-processing is performed in membrane separation units for butenes concentration and recovery. Four different process schemes are developed. The performance of each membrane unit is analyzed by appropriately developed performance maps, to identify the operating conditions windows and the membrane permeation properties required to maximize the recovery of the iso-butene produced. An analysis of integrated systems showed a yield of butenes higher than the other reaction products with high butenes recovery in the gas separation section, with values of molar concentration between 75% and 80%.

Investigation of electrolyte leaching in the performance degradation of phosphoric acid-doped polybenzimidazole membrane-based high temperature fuel cells

Science.gov (United States)

Jeong, Yeon Hun; Oh, Kyeongmin; Ahn, Sungha; Kim, Na Young; Byeon, Ayeong; Park, Hee-Young; Lee, So Young; Park, Hyun S.; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Ju, Hyunchul; Kim, Jin Young

2017-09-01

Precise monitoring of electrolyte leaching in high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) devices during lifetime tests is helpful in making a diagnosis of their quality changes and analyzing their electrochemical performance degradation. Here, we investigate electrolyte leaching in the performance degradation of phosphoric acid (PA)-doped polybenzimidazole (PBI) membrane-based HT-PEMFCs. We first perform quantitative analyses to measure PA leakage during cell operation by spectrophotometric means, and a higher PA leakage rate is detected when the current density is elevated in the cell. Second, long-term degradation tests under various current densities of the cells and electrochemical impedance spectroscopy (EIS) analysis are performed to examine the influence of PA loss on the membrane and electrodes during cell performance degradation. The combined results indicate that PA leakage affect cell performance durability, mostly due to an increase in charge transfer resistance and a decrease in the electrochemical surface area (ECSA) of the electrodes. Additionally, a three-dimensional (3-D) HT-PEMFC model is applied to a real-scale experimental cell, and is successfully validated against the polarization curves measured during various long-term experiments. The simulation results highlight that the PA loss from the cathode catalyst layer (CL) is a significant contributor to overall performance degradation.

Hydrolytic Degradation and Mechanical Stability of Poly(ε-Caprolactone)/Reduced Graphene Oxide Membranes as Scaffolds for In Vitro Neural Tissue Regeneration.

Science.gov (United States)

Sánchez-González, Sandra; Diban, Nazely; Urtiaga, Ane

2018-03-05

The present work studies the functional behavior of novel poly(ε-caprolactone) (PCL) membranes functionalized with reduced graphene oxide (rGO) nanoplatelets under simulated in vitro culture conditions (phosphate buffer solution (PBS) at 37 °C) during 1 year, in order to elucidate their applicability as scaffolds for in vitro neural regeneration. The morphological, chemical, and DSC results demonstrated that high internal porosity of the membranes facilitated water permeation and procured an accelerated hydrolytic degradation throughout the bulk pathway. Therefore, similar molecular weight reduction, from 80 kDa to 33 kDa for the control PCL, and to 27 kDa for PCL/rGO membranes, at the end of the study, was observed. After 1 year of hydrolytic degradation, though monomers coming from the hydrolytic cleavage of PCL diffused towards the PBS medium, the pH was barely affected, and the rGO nanoplatelets mainly remained in the membranes which envisaged low cytotoxic effect. On the other hand, the presence of rGO nanomaterials accelerated the loss of mechanical stability of the membranes. However, it is envisioned that the gradual degradation of the PCL/rGO membranes could facilitate cells infiltration, interconnectivity, and tissue formation.

Polymer electrolyte membrane water electrolysis: Restraining degradation in the presence of fluctuating power

Science.gov (United States)

Rakousky, Christoph; Reimer, Uwe; Wippermann, Klaus; Kuhri, Susanne; Carmo, Marcelo; Lueke, Wiebke; Stolten, Detlef

2017-02-01

Polymer electrolyte membrane (PEM) water electrolysis generates 'green' hydrogen when conducted with electricity from renewable - but fluctuating - sources like wind or solar photovoltaic. Unfortunately, the long-term stability of the electrolyzer performance is still not fully understood under these input power profiles. In this study, we contrast the degradation behavior of our PEM water electrolysis single cells that occurs under operation with constant and intermittent power and derive preferable operating states. For this purpose, five different current density profiles are used, of which two were constant and three dynamic. Cells operated at 1 A cm-2 show no degradation. However, degradation was observed for the remaining four profiles, all of which underwent periods of high current density (2 A cm-2). Hereby, constant operation at 2 A cm-2 led to the highest degradation rate (194 μV h-1). Degradation can be greatly reduced when the cells are operated with an intermittent profile. Current density switching has a positive effect on durability, as it causes reversible parts of degradation to recover and results in a substantially reduced degradation per mole of hydrogen produced. Two general degradation phenomena were identified, a decreased anode exchange current density and an increased contact resistance at the titanium porous transport layer (Ti-PTL).

RING finger protein 121 facilitates the degradation and membrane localization of voltage-gated sodium channels

Science.gov (United States)

Ogino, Kazutoyo; Low, Sean E.; Yamada, Kenta; Saint-Amant, Louis; Zhou, Weibin; Muto, Akira; Asakawa, Kazuhide; Nakai, Junichi; Kawakami, Koichi; Kuwada, John Y.; Hirata, Hiromi

2015-01-01

Following their synthesis in the endoplasmic reticulum (ER), voltage-gated sodium channels (NaV) are transported to the membranes of excitable cells, where they often cluster, such as at the axon initial segment of neurons. Although the mechanisms by which NaV channels form and maintain clusters have been extensively examined, the processes that govern their transport and degradation have received less attention. Our entry into the study of these processes began with the isolation of a new allele of the zebrafish mutant alligator, which we found to be caused by mutations in the gene encoding really interesting new gene (RING) finger protein 121 (RNF121), an E3-ubiquitin ligase present in the ER and cis-Golgi compartments. Here we demonstrate that RNF121 facilitates two opposing fates of NaV channels: (i) ubiquitin-mediated proteasome degradation and (ii) membrane localization when coexpressed with auxiliary NaVβ subunits. Collectively, these results indicate that RNF121 participates in the quality control of NaV channels during their synthesis and subsequent transport to the membrane. PMID:25691753

Sinalbin degradation products in mild yellow mustard paste

Directory of Open Access Journals (Sweden)

Paunović Dragana

2012-01-01

Full Text Available Sinalbin degradation products in mild yellow mustard paste were investigated. The analyzed material consisted of a mild yellow mustard paste condiment and ground white mustard seeds which were originally used in the mustard paste production process. The samples were extracted in a Soxhlet extraction system and analyzed by gas chromatography - mass spectrometry (GC-MS technique. The only sinalbin degradation product in ground mustard seeds was 2-(4-hydroxyphenylacetonitrile. The most abundant sinalbin degradation product in yellow mustard paste was 4-(hydroxymethylphenol. Other compounds identified in this sample were: 4-methyl phenol, 4-ethyl phenol, 4-(2-hydroxyethylphenol and 2-(4-hydroxyphenyl ethanoic acid.

Proteasome-mediated degradation of integral inner nuclear membrane protein emerin in fibroblasts lacking A-type lamins

International Nuclear Information System (INIS)

Muchir, Antoine; Massart, Catherine; Engelen, Baziel G. van; Lammens, Martin; Bonne, Gisele; Worman, Howard J.

2006-01-01

We previously identified and characterized a homozygous LMNA nonsense mutation leading to the absence of A-type lamins in a premature neonate who died at birth. We show here that the absence of A-type lamins is due to degradation of the aberrant mRNA transcript with a premature termination codon. In cultured fibroblasts from the subject with the homozygous LMNA nonsense mutation, there was a decreased steady-state expression of the integral inner nuclear membrane proteins emerin and nesprin-1α associated with their mislocalization to the bulk endoplasmic reticulum and a hyperphosphorylation of emerin. To determine if decreased emerin expression occurred post-translationally, we treated cells with a selective proteasome inhibitor and observed an increase in expression. Our results show that mislocalization of integral inner nuclear membrane proteins to the endoplasmic reticulum in human cells lacking A-type lamins leads to their degradation and provides the first evidence that their degradation is mediated by the proteasome

21 CFR 864.7320 - Fibrinogen/fibrin degradation products assay.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Fibrinogen/fibrin degradation products assay. 864.7320 Section 864.7320 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN....7320 Fibrinogen/fibrin degradation products assay. (a) Identification. A fibrinogen/fibrin degradation...

Modelling the behaviour of organic degradation products

International Nuclear Information System (INIS)

Cross, J.E.; Ewart, F.T.; Greenfield, B.F.

1989-03-01

Results are presented from recent studies at Harwell which show that the degradation products which are formed when certain organic waste materials are exposed to the alkaline conditions typical of a cementitious environment, can enhance the solubility of plutonium, even at pH values as high as 12, by significant factors. Characterisation of the degradation products has been undertaken but the solubility enhancement does not appear to be related to the concentration of any of the major organic species that have been identified in the solutions. While it has not been possible to identify by analysis the organic ligand responsible for the increased solubility of plutonium, the behaviour of D-Saccharic acid does approach the behaviour of the degradation products. The PHREEQE code has been used to simulate the solubility of plutonium in the presence of D-Saccharic acid and other model degradation products, in order to explain the solubility enhancement. The extrapolation of the experimental conditions to the repository is the major objective, but in this work the ability of a model to predict the behaviour of plutonium over a range of experimental conditions has been tested. (author)

Open-source FCPEM-Performance & Durability Model Consideration of Membrane Properties on Cathode Degradation

Energy Technology Data Exchange (ETDEWEB)

Knights, Shanna [Ballard Fuel Cell Systems, Bend, OR (United States); Harvey, David [Ballard Fuel Cell Systems, Bend, OR (United States)

2017-01-20

The durability of PEM fuel cells is a primary requirement for large scale commercialization of these power systems in transportation and stationary market applications which target operational lifetimes of 5,000 hours and 60,000 hours by 2020, respectively. Key degradation modes contributing to fuel cell lifetime limitations have been largely associated with the platinum-based cathode catalyst layer. Furthermore, as fuel cells are driven to low cost materials and lower catalyst loadings in order to meet the cost targets for commercialization, the catalyst durability has become even more important. While over the past few years significant progress has been made in identifying the underlying causes of fuel cell degradation and key parameters that greatly influence the degradation rates, many gaps with respect to knowledge of the driving mechanisms still exist; in particular, the acceleration of the mechanisms due to different membrane compositions remains an area not well understood. The focus of this project extension was to enhance the predictive capability of the PEM Fuel Cell Performance & Durability Model called FC-APOLLO (Application Package for Open-source Long Life Operation) by including interaction effects of membrane transport properties such as water transport, changes in proton conductivity, and overall water uptake/adsorption and the state of the catalyst layer local conditions to further understand the driving forces for platinum dissolution.

Analysis of the Durability of PEM FC Membrane Electrode Assemblies in Automotive Applications through the Fundamental Understanding of Membrane and MEA Degradation Pathways

Energy Technology Data Exchange (ETDEWEB)

Perry, Randal L. [DuPont

2013-10-31

The Project focused on mitigation of degradation processes on membrane electrode assemblies. The approach was to develop a model to improve understanding of the mechanisms, and to use it to focus mitigation strategies. The detailed effects of various accelerated stress tests (ASTs) were evaluated to determine the best subset to use in model development. A combination of ASTs developed by the Fuel Cell Commercialization Conference of Japan and the Fuel Cell Tech Team were selected for use. The ASTs were compared by measuring effects on performance, running in-situ diagnostics, and performing microscopic analyses of the membrane electrode assemblies after the stress tests were complete. Nissan ran FCCJ AST protocols and performed in situ and ex-situ electrochemical testing. DuPont ran FCTT and USFCC AST protocols, performed scanning and transmission electron microscopy and ran in-situ electrochemical tests. Other ex-situ testing was performed by IIT, along with much of the data analysis and model development. These tests were then modified to generate time-dependent data of the degradation mechanisms. Three different catalyst types and four membrane variants were then used to generate data for a theoretically-based degradation model. An important part of the approach was to use commercially available materials in the electrodes and membranes made in scalable semiworks processes rather than lab-based materials. This constraint ensured all materials would be practicable for full-scale testing. The initial model for the electrode layer was tested for internal consistency and agreement with the data. A Java-based computer application was developed to analyze the time-dependent AST data using polarization curves with four different cathode gas feeds and generate model parameters. Data showed very good reproducibility and good consistency as cathode catalyst loadings were varied. At the point of termination of the project, a basic electrode model was in hand with several

Vitamin C Degradation Products and Pathways in the Human Lens*

OpenAIRE

Nemet, Ina; Monnier, Vincent M.

2011-01-01

Vitamin C and its degradation products participate in chemical modifications of proteins in vivo through non-enzymatic glycation (Maillard reaction) and formation of different products called advanced glycation end products. Vitamin C levels are particularly high in selected tissues, such as lens, brain and adrenal gland, and its degradation products can inflict substantial protein damage via formation of advanced glycation end products. However, the pathways of in vivo vitamin C degradation ...

Liquid chromatography and liquid chromatography-mass spectrometry analysis of donepezil degradation products

Directory of Open Access Journals (Sweden)

Mladenović Aleksandar R.

2015-01-01

Full Text Available This study describes the investigation of degradation products of donepezil (DP using stability indicating RP-HPLC method for determination of donepezil, which is a centrally acting reversible acetylcholinesterase inhibitor. In order to investigate the stability of drug and formed degradation products, a forced degradation study of drug sample and finished product under different forced degradation conditions has been conducted. Donepezil hydrochloride and donepezil tablets were subjected to stress degradation conditions recommended by International Conference on Harmonization (ICH. Donepezil hydrochloride solutions were subjected to acid and alkali hydrolysis, chemical oxidation and thermal degradation. Significant degradation was observed under alkali hydrolysis and oxidative degradation conditions. Additional degradation products were observed under the conditions of oxidative degradation. The degradation products observed during forced degradation studies were monitored using the high performance liquid chromatography (HPLC method developed. The parent method was modified in order to obtain LC-MS compatible method which was used to identify the degradation products from forced degradation samples using high resolution mass spectrometry. The mass spectrum provided the precise mass from which derived molecular formula of drug substance and degradation products formed and proved the specificity of the method unambiguously. [Projekat Ministarstva nauke Republike Srbije, br. 172013

Anthocyanins degradation during storage of Hibiscus sabdariffa extract and evolution of its degradation products.

Science.gov (United States)

Sinela, André; Rawat, Nadirah; Mertz, Christian; Achir, Nawel; Fulcrand, Hélène; Dornier, Manuel

2017-01-01

Degradation parameters of two main anthocyanins from roselle extract (Hibiscus sabdariffa L.) stored at different temperatures (4-37°C) over 60days were determined. Anthocyanins and some of their degradation products were monitored and quantified using HPLC-MS and DAD. Degradation of anthocyanins followed first-order kinetics and reaction rate constants (k values), which were obtained by non-linear regression, showed that the degradation rate of delphinidin 3-O-sambubioside was higher than that of cyanidin 3-O-sambubioside with k values of 9.2·10(-7)s(-1) and 8.4·10(-7)s(-1) at 37°C respectively. The temperature dependence of the rate of anthocyanin degradation was modeled by the Arrhenius equation. Degradation of delphinidin 3-O-sambubioside (Ea=90kJmol(-1)) tended to be significantly more sensitive to an increase in temperature than cyanidin 3-O-sambubioside (Ea=80kJmol(-1)). Degradation of these anthocyanins formed scission products (gallic and protocatechuic acids respectively) and was accompanied by an increase in polymeric color index. Copyright © 2016 Elsevier Ltd. All rights reserved.

Membrane bioreactors' potential for ethanol and biogas production: a review.

Science.gov (United States)

Ylitervo, Päivi; Akinbomia, Julius; Taherzadeha, Mohammad J

2013-01-01

Companies developing and producing membranes for different separation purposes, as well as the market for these, have markedly increased in numbers over the last decade. Membrane and separation technology might well contribute to making fuel ethanol and biogas production from lignocellulosic materials more economically viable and productive. Combining biological processes with membrane separation techniques in a membrane bioreactor (MBR) increases cell concentrations extensively in the bioreactor. Such a combination furthermore reduces product inhibition during the biological process, increases product concentration and productivity, and simplifies the separation of product and/or cells. Various MBRs have been studied over the years, where the membrane is either submerged inside the liquid to be filtered, or placed in an external loop outside the bioreactor. All configurations have advantages and drawbacks, as reviewed in this paper. The current review presents an account of the membrane separation technologies, and the research performed on MBRs, focusing on ethanol and biogas production. The advantages and potentials of the technology are elucidated.

Sinalbin degradation products in mild yellow mustard paste

OpenAIRE

Paunović, Dragana; Šolević-Knudsen, Tatjana; Krivokapić, Mirjana; Zlatković, Branislav; Antić, Mališa

2012-01-01

Sinalbin degradation products in mild yellow mustard paste were investigated. The analyzed material consisted of a mild yellow mustard paste condiment and ground white mustard seeds which were originally used in the mustard paste production process. The samples were extracted in a Soxhlet extraction system and analyzed by gas chromatography - mass spectrometry (GC-MS) technique. The only sinalbin degradation product in ground mustard seeds was 2-(4-hydroxyphenyl)acetonitrile. The most a...

Carbamazepine degradation using a N-doped TiO_2 coated photocatalytic membrane reactor: Influence of physical parameters

International Nuclear Information System (INIS)

Horovitz, Inna; Avisar, Dror; Baker, Mark A.; Grilli, Rossana; Lozzi, Luca; Di Camillo, Daniela; Mamane, Hadas

2016-01-01

Highlights: • UV–vis N-doped TiO_2 was deposited by sol-gel onto Al_2O_3 microfiltration membranes. • Coating decreased permeability by 50 and 12% for 200- and 800-nm Al_2O_3 membranes. • Flow through membrane results in higher reaction rates compared to flow on top. • Higher vis photocatalytic activity for N-doped TiO_2 vs. non-doped TiO_2 membranes. • Mass transfer is a critical parameter for the design of immobilized PMR. - Abstract: Commercial α-Al_2O_3 photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO_2 photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO_2 films are in the form of anatase with 78–84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3–0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO_2-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydraulic effect and in-pore PCA. N-doped TiO_2-coated membranes showed enhanced activity for UV wavelengths, in addition to activity under visible light. Experiments of PCA under varying flow rates concluded that the process is in the mass-transfer control regime. Carbamazepine removal rate increased with temperature, despite the decrease in dissolved oxygen concentration.

Membrane engineering via trans unsaturated fatty acids production improves Escherichia coli robustness and production of biorenewables.

Science.gov (United States)

Tan, Zaigao; Yoon, Jong Moon; Nielsen, David R; Shanks, Jacqueline V; Jarboe, Laura R

2016-05-01

Constructing microbial biocatalysts that produce biorenewables at economically viable yields and titers is often hampered by product toxicity. For production of short chain fatty acids, membrane damage is considered the primary mechanism of toxicity, particularly in regards to membrane integrity. Previous engineering efforts in Escherichia coli to increase membrane integrity, with the goal of increasing fatty acid tolerance and production, have had mixed results. Herein, a novel approach was used to reconstruct the E. coli membrane by enabling production of a novel membrane component. Specifically, trans unsaturated fatty acids (TUFA) were produced and incorporated into the membrane of E. coli MG1655 by expression of cis-trans isomerase (Cti) from Pseudomonas aeruginosa. While the engineered strain was found to have no increase in membrane integrity, a significant decrease in membrane fluidity was observed, meaning that membrane polarization and rigidity were increased by TUFA incorporation. As a result, tolerance to exogenously added octanoic acid and production of octanoic acid were both increased relative to the wild-type strain. This membrane engineering strategy to improve octanoic acid tolerance was found to require fine-tuning of TUFA abundance. Besides improving tolerance and production of carboxylic acids, TUFA production also enabled increased tolerance in E. coli to other bio-products, e.g. alcohols, organic acids, aromatic compounds, a variety of adverse industrial conditions, e.g. low pH, high temperature, and also elevated styrene production, another versatile bio-chemical product. TUFA permitted enhanced growth due to alleviation of bio-product toxicity, demonstrating the general effectiveness of this membrane engineering strategy towards improving strain robustness. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Degradation behaviour and excess sludge production of mixed biocoenoses in membrane bioreactors; Abbauverhalten und Ueberschussschlammproduktion von Mischbiozoenosen in Membranbioreaktoren

Energy Technology Data Exchange (ETDEWEB)

Kraume, M. [Technische Univ. Berlin (Germany). Inst. fuer Verfahrenstechnik; Szewzyk, U. [Technische Univ. Berlin (Germany). Fachgebiet Oekologie und Mikroorganismen

1999-07-01

In three different membrane bioreactors (technical scale and pilot scale), process engineering and microbiological studies were carried out over a period of up to three years. The sewage used was sugar-beet molasses slop and municipal sewage. All three plants exhibited stable COD degradation rates of 87 % (molasses slop) and 95 % (municipal sewage). They could be operated during the test period without regular removal of excess sludge. (orig.) [German] An drei unterschiedlichen Membranbioreaktoren (Technikums- und Pilotmassstab) wurden ueber einen Zeitraum von bis zu 3 Jahren verfahrenstechnische und mirkobiologische Untersuchungen durchgefuehrt. Als Abwasser wurde Zuckerrueben-Melasseschlempe und kommunales Abwasser eingesetzt. Alle drei Anlagen zeigten stabile CSB-Abbaugrade von 87% (Melasseschlempe) und 95% (kommunale Abwasser). Sie konnten ueber den Vesuchszeitraum ohne regelmaessigen Abzug von Ueberschussschlamm betrieben werden. (orig.)

Charcoal production and environmental degradation

International Nuclear Information System (INIS)

Hosier, R.H.

1993-01-01

This paper examines the environmental impacts of continued tree harvesting for charcoal production to supply the urban areas in Tanzania. Woodlands appear to recover relatively well following harvesting for charcoal production. Selective harvesting, where the high quality, low cost fuel production species and specimens are culled first from a piece of land, serves to maintain the viability of the woodlands resource while providing charcoal. This recovery period can be prolonged through any number of human induced activities, such as heavy grazing, multiple burns and extended cultivation periods. At the same time, post-harvest management techniques, such as coppice management, sprout protection and fertilization, can also improve the ability of woodlands to recover following harvesting. The environmental history of a given area determines why certain areas continue to be strong suppliers of woodfuel while others are not. For example, Shinyanga started from a low productivity base and has been degraded by successive waves of tree harvesting compounded by heavy grazing pressure. It is this multiple complex of pressures over a long period of time on land which is intrinsically of low productivity, and not the harvesting of woodlands for fuels, which has led to the environmental degradation in these areas. (author)

Detergent resistant membrane-associated IDE in brain tissue and cultured cells: Relevance to Aβ and insulin degradation

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Castaño Eduardo M

2008-12-01

Full Text Available Abstract Background Insulin degrading enzyme (IDE is implicated in the regulation of amyloid β (Aβ steady-state levels in the brain, and its deficient expression and/or activity may be a risk factor in sporadic Alzheimer's disease (AD. Although IDE sub-cellular localization has been well studied, the compartments relevant to Aβ degradation remain to be determined. Results Our results of live immunofluorescence, immuno gold electron-microscopy and gradient fractionation concurred to the demonstration that endogenous IDE from brain tissues and cell cultures is, in addition to its other localizations, a detergent-resistant membrane (DRM-associated metallopeptidase. Our pulse chase experiments were in accordance with the existence of two pools of IDE: the cytosolic one with a longer half-life and the membrane-IDE with a faster turn-over. DRMs-associated IDE co-localized with Aβ and its distribution (DRMs vs. non-DRMs and activity was sensitive to manipulation of lipid composition in vitro and in vivo. When IDE was mis-located from DRMs by treating cells with methyl-β-cyclodextrin (MβCD, endogenous Aβ accumulated in the extracellular space and exogenous Aβ proteolysis was impaired. We detected a reduced amount of IDE in DRMs of membranes isolated from mice brain with endogenous reduced levels of cholesterol (Chol due to targeted deletion of one seladin-1 allele. We confirmed that a moderate shift of IDE from DRMs induced a substantial decrement on IDE-mediated insulin and Aβ degradation in vitro. Conclusion Our results support the notion that optimal substrate degradation by IDE may require its association with organized-DRMs. Alternatively, DRMs but not other plasma membrane regions, may act as platforms where Aβ accumulates, due to its hydrophobic properties, reaching local concentration close to its Km for IDE facilitating its clearance. Structural integrity of DRMs may also be required to tightly retain insulin receptor and IDE for

Bioinspired Synthesis of Photocatalytic Nanocomposite Membranes Based on Synergy of Au-TiO2 and Polydopamine for Degradation of Tetracycline under Visible Light.

Science.gov (United States)

Wang, Chen; Wu, Yilin; Lu, Jian; Zhao, Juan; Cui, Jiuyun; Wu, Xiuling; Yan, Yongsheng; Huo, Pengwei

2017-07-19

A bioinspired photocatalytic nanocomposite membrane was successfully prepared via polydopamine (pDA)-coated poly(vinylidene fluoride) (PVDF) membrane, as a secondary platform for vacuum-filtrated Au-TiO 2 nanocomposites, with enhanced photocatalytic activity. The degradation efficiency of Au-TiO 2 /pDA/PVDF membranes reached 92% when exposed to visible light for 120 min, and the degradation efficiency of Au-TiO 2 /pDA/PVDF membranes increased by 26% compared to that of Au-TiO 2 powder and increased by 51% compared to that of TiO 2 /pDA/PVDF nanocomposite membranes. The degradation efficiency remained about 90% after five cycle experiments, and the Au-TiO 2 /pDA/PVDF nanocomposite membranes showed good stability, regeneration performance, and easy recycling. The pDA coating not only served as a bioadhesion interface to improve the bonding force between the catalyst and the membrane substrate but also acted as a photosensitizer to broaden the wavelength response range of TiO 2 , and the structure of Au-TiO 2 /pDA/PVDF also improves the transfer rate of photogenerated electrons; the surface plasmon resonance effect of Au also played a positive role in improving the activity of the catalyst. Therefore, we believe that this study opens up a new strategy in preparing the bioinspired photocatalytic nanocomposite membrane for potential wastewater purification, catalysis, and as a membrane separation field.

Removal of nalidixic acid and its degradation products by an integrated MBR-ozonation system.

Science.gov (United States)

Pollice, A; Laera, G; Cassano, D; Diomede, S; Pinto, A; Lopez, A; Mascolo, G

2012-02-15

Chemical-biological degradation of a widely spread antibacterial (nalidixic acid) was successfully obtained by an integrated membrane bioreactor (MBR)-ozonation process. The composition of the treated solution simulated the wastewater from the production of the target pharmaceutical, featuring high salinity and a relevant concentration of sodium acetate. Aim of treatment integration was to exploit the synergistic effects of chemical oxidation and bioprocesses, by adopting the latter to remove most of the COD and the ozonation biodegradable products. Integration was achieved by placing ozonation in the recirculation stream of the bioreactor effluent. The recirculation flow rate was three-fold the MBR feed, and the performance of the integrated system was compared to the standard polishing configuration (single ozonation step after the MBR). Results showed that the introduction of the ozonation step did not cause relevant drawbacks to both biological and filtration processes. nalidixic acid passed undegraded through the MBR and was completely removed in the ozonation step. Complete degradation of most of the detected ozonation products was better achieved with the integrated MBR-ozonation process than using the sequential treatment configuration, i.e. ozone polishing after MBR, given the same ozone dosage. Copyright © 2011 Elsevier B.V. All rights reserved.

Lactic acid Production with in situ Extraction in Membrane Bioreactor

Directory of Open Access Journals (Sweden)

Hamidreza Ghafouri Taleghani

2017-01-01

Full Text Available Background and Objective: Lactic acid is widely used in the food, chemical and pharmaceutical industries. The major problems associated with lactic acid production are substrate and end-product inhibition, and by-product formation. Membrane technologyrepresents one of the most effective processes for lactic acid production. The aim of this work is to increase cell density and lactic acid productivity due to reduced inhibition effect of substrate and product in membrane bioreactor.Material and Methods: In this work, lactic acid was produced from lactose in membrane bioreactor. A laboratory scale membrane bioreactor was designed and fabricated. Five types of commercial membranes were tested at the same operating conditions (transmembrane pressure: 500 KPa and temperature: 25°C. The effects of initial lactose concentration and dilution rate on biomass growth, lactic acid production and substrate utilization were evaluated.Results and Conclusion: The high lactose retention of 79% v v-1 and low lactic acid retention of 22% v v-1 were obtained with NF1 membrane; therefore, this membrane was selected for membrane bioreactor. The maximal productivity of 17.1 g l-1 h-1 was obtainedwith the lactic acid concentration of 71.5 g l-1 at the dilution rate of 0.24 h−1. The maximum concentration of lactic acid was obtained at the dilution rate of 0.04 h−1. The inhibiting effect of lactic acid was not observed at high initial lactose concentration. The critical lactose concentration at which the cell growth severely hampered was 150 g l-1. This study proved that membrane bioreactor had great advantages such as elimination of substrate and product inhibition, high concentration of process substrate, high cell density,and high lactic acid productivity.Conflict of interest: There is no conflict of interest.

Enhancement of organic matter degradation and methane gas production of anaerobic granular sludge by degasification of dissolved hydrogen gas.

Science.gov (United States)

Satoh, Hisashi; Bandara, Wasala M K R T W; Sasakawa, Manabu; Nakahara, Yoshihito; Takahashi, Masahiro; Okabe, Satoshi

2017-11-01

A hollow fiber degassing membrane (DM) was applied to enhance organic matter degradation and methane gas production of anaerobic granular sludge process by reducing the dissolved hydrogen gas (D-H 2 ) concentration in the liquid phase. DM was installed in the bench-scale anaerobic granular sludge reactors and D-H 2 was removed through DM using a vacuum pump. Degasification improved the organic matter degradation efficiency to 79% while the efficiency was 62% without degasification at 12,000mgL -1 of the influent T-COD concentration. Measurement of D-H 2 concentrations in the liquid phase confirmed that D-H 2 was removed by degasification. Furthermore, the effect of acetate concentrations on the organic matter degradation efficiency was investigated. At acetate concentrations above 3gL -1 , organic matter degradation deteriorated. Degasification enhanced the propionate and acetate degradation. These results suggest that degasification reduced D-H 2 concentration and volatile fatty acids concentrations, prevented pH drop, and subsequent enhanced organic matter degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of Furfural on Rapid Ethanol Production Using a Membrane Bioreactor

Directory of Open Access Journals (Sweden)

Mohammad J. Taherzadeh

2013-03-01

Full Text Available A membrane bioreactor was developed to counteract the inhibition effect of furfural in ethanol production. Furfural, a major inhibitor in lignocellulosic hydrolyzates, is a highly toxic substance which is formed from pentose sugars released during the acidic degradation of lignocellulosic materials. Continuous cultivations with complete cell retention were performed at a high dilution rate of 0.5 h−1. Furfural was added directly into the bioreactor by pulse injection or by addition into the feed medium to obtain furfural concentrations ranging from 0.1 to 21.8 g L−1. At all pulse injections of furfural, the yeast was able to convert the furfural very rapidly by in situ detoxification. When injecting 21.8 g L−1 furfural to the cultivation, the yeast converted it by a specific conversion rate of 0.35 g g−1 h−1. At high cell density, Saccharomyces cerevisiae could tolerate very high furfural levels without major changes in the ethanol production. During the continuous cultures when up to 17.0 g L−1 furfural was added to the inlet medium, the yeast successfully produced ethanol, whereas an increase of furfural to 18.6 and 20.6 g L−1 resulted in a rapidly decreasing ethanol production and accumulation of sugars in the permeate. This study show that continuous ethanol fermentations by total cell retention in a membrane bioreactor has a high furfural tolerance and can conduct rapid in situ detoxification of medium containing high furfural concentrations.

Effective Degradation of Aqueous Tetracycline Using a Nano-TiO2/Carbon Electrocatalytic Membrane

Directory of Open Access Journals (Sweden)

Zhimeng Liu

2016-05-01

Full Text Available In this work, an electrocatalytic membrane was prepared to degrade aqueous tetracycline (TC using a carbon membrane coated with nano-TiO2 via a sol-gel process. SEM, XRD, EDS, and XPS were used to characterize the composition and structure of the electrocatalytic membrane. The effect of operating conditions on the removal rate of tetracycline was investigated systematically. The results show that the chemical oxygen demand (COD removal rate increased with increasing residence time while it decreased with increasing the initial concentration of tetracycline. Moreover, pH had little effect on the removal of tetracycline, and the electrocatalytic membrane could effectively remove tetracycline with initial concentration of 50 mg·L−1 (pH, 3.8–9.6. The 100% tetracycline and 87.8% COD removal rate could be achieved under the following operating conditions: tetracycline concentration of 50 mg·L−1, current density of 1 mA·cm−2, temperature of 25 °C, and residence time of 4.4 min. This study provides a new and feasible method for removing antibiotics in water with the synergistic effect of electrocatalytic oxidation and membrane separation. It is evident that there will be a broad market for the application of electrocatalytic membrane in the field of antibiotic wastewater treatment.

Four new degradation products of doxorubicin: An application of forced degradation study and hyphenated chromatographic techniques

Directory of Open Access Journals (Sweden)

Dheeraj Kaushik

2015-10-01

Full Text Available Forced degradation study on doxorubicin (DOX was carried out under hydrolytic condition in acidic, alkaline and neutral media at varied temperatures, as well as under peroxide, thermal and photolytic conditions in accordance with International Conference on Harmonization (ICH guidelines Q1(R2. It was found extremely unstable to alkaline hydrolysis even at room temperature, unstable to acid hydrolysis at 80 °C, and to oxidation at room temperature. It degraded to four products (O-I–O-IV in oxidative condition, and to single product (A-I in acid hydrolytic condition. These products were resolved on a C8 (150 mm×4.6 mm, 5 µm column with isocratic elution using mobile phase consisting of HCOONH4 (10 mM, pH 2.5, acetonitrile and methanol (65:15:20, v/v/v. Liquid chromatography–photodiode array (LC–PDA technique was used to ascertain the purity of the products noted in LC–UV chromatogram. For their characterization, a six stage mass fragmentation (MS6 pattern of DOX was outlined through mass spectral studies in positive mode of electrospray ionization (+ESI as well as through accurate mass spectral data of DOX and the products generated through liquid chromatography–time of flight mass spectrometry (LC–MS–TOF on degraded drug solutions. Based on it, O-I–O-IV were characterized as 3-hydroxy-9-desacetyldoxorubicin-9-hydroperoxide, 1-hydroxy-9-desacetyldoxorubicin-9-hydroperoxide, 9-desacetyldoxorubicin-9-hydroperoxide and 9-desacetyldoxorubicin, respectively, whereas A-I was characterized as deglucosaminyl doxorubicin. While A-I was found to be a pharmacopoeial impurity, all oxidative products were found to be new degradation impurities. The mechanisms and pathways of degradation of doxorubicin were outlined and discussed. Keywords: Doxorubicin, TOF, Forced degradation, Liquid chromatography, Degradation product, Mass fragmentation pattern

The tissue-specific Rep8/UBXD6 tethers p97 to the endoplasmic reticulum membrane for degradation of misfolded proteins

DEFF Research Database (Denmark)

Madsen, Louise; Kriegenburg, Franziska; Lages Lino Vala, Andrea

2011-01-01

is a transmembrane protein that localizes to the ER membrane with its UBX domain facing the cytoplasm. Knock-down of Rep8 expression in human cells leads to a decreased association of p97 with the ER membrane and concomitantly a retarded degradation of misfolded ER-derived proteasome substrates. Thus, Rep8 tethers p......The protein known as p97 or VCP in mammals and Cdc48 in yeast is a versatile ATPase complex involved in several biological functions including membrane fusion, protein folding, and activation of membrane-bound transcription factors. In addition, p97 plays a central role in degradation of misfolded...... protein named Rep8 or Ubxd6 as a new cofactor of p97. Mouse Rep8 is highly tissue-specific and abundant in gonads. In testes, Rep8 is expressed in post-meiotic round spermatids, whereas in ovaries Rep8 is expressed in granulosa cells. Rep8 associates directly with p97 via its UBX domain. We show that Rep8...

Effects of organic degradation products on the sorption of actinides

International Nuclear Information System (INIS)

Baston, G.M.N.; Berry, J.A.; Bond, K.A.; Brownsword, M.; Linklater, C.M.

1992-01-01

Previous work has shown that products from the chemical degradation of cellulosic matter can significantly reduce sorption of uranium(VI) and plutonium(IV) on geological materials. Uranium(IV) batch sorption experiments have now been performed to study the effect of organic degradation products in a reducing environment. Thorium(IV) sorption has also been studied since thorium is an important radioelement in its own right and has potential use as a simulant for other tetravalent actinides. Sorption onto London clay, Caithness flagstones and St. Bees sandstone was investigated. Experimental conditions were chosen to simulate both those expected close to cementitious repository (pH ∝ 11) and at the edge of the zone of migration of the alkaline plume (pH ∝ 8). Work was carried out with both authentic degradation products and with gluconate, acting as a well-characterized simulant for cellulosic degradation products. The results show that the presence of organic species can cause a reduction in sorption. This is especially so in the presence of a high concentration of gluconate ions, but the reduction is significantly less with authentic degradation products. (orig.)

Carbamazepine degradation using a N-doped TiO{sub 2} coated photocatalytic membrane reactor: Influence of physical parameters

Energy Technology Data Exchange (ETDEWEB)

Horovitz, Inna [School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); The Hydro-Chemistry Laboratory, Faculty of Geography and the Environment, Tel Aviv University, Tel Aviv 69978 (Israel); Avisar, Dror [The Hydro-Chemistry Laboratory, Faculty of Geography and the Environment, Tel Aviv University, Tel Aviv 69978 (Israel); Baker, Mark A.; Grilli, Rossana [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom); Lozzi, Luca; Di Camillo, Daniela [Department of Physical and Chemical Sciences, University of L' Aquila, Via Vetoio, I-67100 L' Aquila (Italy); Mamane, Hadas, E-mail: hadasmg@post.tau.ac.il [School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

2016-06-05

Highlights: • UV–vis N-doped TiO{sub 2} was deposited by sol-gel onto Al{sub 2}O{sub 3} microfiltration membranes. • Coating decreased permeability by 50 and 12% for 200- and 800-nm Al{sub 2}O{sub 3} membranes. • Flow through membrane results in higher reaction rates compared to flow on top. • Higher vis photocatalytic activity for N-doped TiO{sub 2} vs. non-doped TiO{sub 2} membranes. • Mass transfer is a critical parameter for the design of immobilized PMR. - Abstract: Commercial α-Al{sub 2}O{sub 3} photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO{sub 2} photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO{sub 2} films are in the form of anatase with 78–84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3–0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO{sub 2}-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydraulic effect and in-pore PCA. N-doped TiO{sub 2}-coated membranes showed enhanced activity for UV wavelengths, in addition to activity under visible light. Experiments of PCA under varying flow rates concluded that the process is in the mass-transfer control regime. Carbamazepine removal rate increased with temperature, despite the decrease in dissolved oxygen concentration.

A Review on Catalytic Membranes Production and Applications

Directory of Open Access Journals (Sweden)

Heba Abdallah

2017-05-01

Full Text Available The development of the chemical industry regarding reducing the production cost and obtaining a high-quality product with low environmental impact became the essential requirements of the world in these days. The catalytic membrane is considered as one of the new alternative solutions of catalysts problems in the industries, where the reaction and separation can be amalgamated in one unit. The catalytic membrane has numerous advantages such as breaking the thermodynamic equilibrium limitation, increasing conversion rate, reducing the recycle and separation costs. But the limitation or most disadvantages of catalytic membranes related to the high capital costs for fabrication or the fact that manufacturing process is still under development. This review article summarizes the most recent advances and research activities related to preparation, characterization, and applications of catalytic membranes. In this article, various types of catalytic membranes are displayed with different applications and explained the positive impacts of using catalytic membranes in various reactions. Copyright © 2017 BCREC Group. All rights reserved. Received: 1st April 2016; Revised: 14th February 2017; Accepted: 22nd February 2017 How to Cite: Abdallah, H. (2017. A Review on Catalytic Membranes Production and Applications. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2: 136-156 (doi:10.9767/bcrec.12.2.462.136-156 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.462.136-156

Effects of organic degradation products on the sorption of actinides

Energy Technology Data Exchange (ETDEWEB)

Baston, G.M.N.; Berry, J.A.; Bond, K.A.; Brownsword, M.; Linklater, C.M. (AEA Decommissioning and Radwaste, Harwell Lab. (United Kingdom))

1992-01-01

Previous work has shown that products from the chemical degradation of cellulosic matter can significantly reduce sorption of uranium(VI) and plutonium(IV) on geological materials. Uranium(IV) batch sorption experiments have now been performed to study the effect of organic degradation products in a reducing environment. Thorium(IV) sorption has also been studied since thorium is an important radioelement in its own right and has potential use as a simulant for other tetravalent actinides. Sorption onto London clay, Caithness flagstones and St. Bees sandstone was investigated. Experimental conditions were chosen to simulate both those expected close to cementitious repository (pH [proportional to] 11) and at the edge of the zone of migration of the alkaline plume (pH [proportional to] 8). Work was carried out with both authentic degradation products and with gluconate, acting as a well-characterized simulant for cellulosic degradation products. The results show that the presence of organic species can cause a reduction in sorption. This is especially so in the presence of a high concentration of gluconate ions, but the reduction is significantly less with authentic degradation products. (orig.).

Core degradation and fission product release

International Nuclear Information System (INIS)

Wright, R.W.; Hagen, S.J.L.

1992-01-01

Experiments on core degradation and melt progression in severe LWR accidents have provided reasonable understanding of the principal processes involved in the early phase of melt progression that extends through core degradation and metallic material melting and relocation. A general but not a quantitative understanding of late phase melt progression that involves ceramic material melting and relocation has also been obtained, primarily from the TMI-2 core examination. A summary is given of the current state of knowledge on core degradation and melt progression obtained from these integral experiments and of the principal remaining significant uncertainties. A summary is also given of the principal results on in-vessel fission product release obtained from these experiments. (author). 8 refs, 5 figs, 3 tabs

Novel amphiphilic polymeric ionic liquid-solid phase micro-extraction membrane for the preconcentration of aniline as degradation product of azo dye Orange G under sonication by liquid chromatography-tandem mass spectrometry.

Science.gov (United States)

Cai, Mei-Qiang; Wei, Xiao-Qing; Du, Chun-Hui; Ma, Xu-Ming; Jin, Mi-Cong

2014-07-04

A novel amphiphilic polymeric ionic liquid membrane containing a hydrophilic bromide anion and a hydrophobic carbonyl group was synthesized in dimethylformamide (DMF) systems using the ionic liquid 1-butyl-3-vinylimidazolium bromide (BVImBr) and the methylmethacrylate (MMA) as monomers. The prepared amphiphilic ploy-methylmethacrylate-1-butyl-3-vinylimidazolium bromide (MMA-BVImBr) was characterized by a scanning electron microscope and an infrared spectrum instrument. The results of solid-phase micro-extraction membrane (SPMM) experiments showed that the adsorption capacity of membrane was about 0.76μgμg(-1) for aniline. Based on this, a sensitive method for the determination of trace aniline, as a degradation product of azo dye Orange G under sonication, was developed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The calibration curve showed a good linearity ranging from 0.5 to 10.0μgL(-1) with a correlation coefficient value of 0.9998. The limit of quantification was 0.5μgL(-1). The recoveries ranged from 90.6% to 96.1%. The intra- and inter-day relative standard deviations were less than 8.3% and 10.9%. The developed SPMM-LC-MS/MS method was used successfully for preconcentration of trace aniline produced during the sonication of Orange G solution. Copyright © 2014 Elsevier B.V. All rights reserved.

Ion transport membrane reactor systems and methods for producing synthesis gas

Science.gov (United States)

Repasky, John Michael

2015-05-12

Embodiments of the present invention provide cost-effective systems and methods for producing a synthesis gas product using a steam reformer system and an ion transport membrane (ITM) reactor having multiple stages, without requiring inter-stage reactant injections. Embodiments of the present invention also provide techniques for compensating for membrane performance degradation and other changes in system operating conditions that negatively affect synthesis gas production.

Mapping intermediate degradation products of poly(lactic-co-glycolic acid) in vitro.

Science.gov (United States)

Li, Jian; Nemes, Peter; Guo, Ji

2018-04-01

There is widespread interest in using absorbable polymers, such as poly(lactic-co-glycolic acid) (PLGA), as components in the design and manufacture of new-generation drug eluting stents (DES). PLGA undergoes hydrolysis to progressively degrade through intermediate chemical entities to simple organic acids that are ultimately absorbed by the human body. Understanding the composition and structure of these intermediate degradation products is critical not only to elucidate polymer degradation pathways accurately, but also to assess the safety and performance of absorbable cardiovascular implants. However, analytical approaches to determining the intermediate degradation products have yet to be established and evaluated in a standard or regulatory setting. Hence, we developed a methodology using electrospray ionization mass spectrometry to qualitatively and quantitatively describe intermediate degradation products generated in vitro from two PLGA formulations commonly used in DES. Furthermore, we assessed the temporal evolution of these degradation products using time-lapse experiments. Our data demonstrated that PLGA degradation products via heterogeneous cleavage of ester bonds are modulated by multiple intrinsic and environmental factors, including polymer chemical composition, degradants solubility in water, and polymer synthesis process. We anticipate the methodologies and outcomes presented in this work will elevate the mechanistic understanding of comprehensive degradation profiles of absorbable polymeric devices, and facilitate the design and regulation of cardiovascular implants by supporting the assessments of the associated biological response to degradation products. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1129-1137, 2018. © 2017 Wiley Periodicals, Inc.

Insulin degradation products from perfused rat kidney

International Nuclear Information System (INIS)

Duckworth, W.C.; Hamel, F.G.; Liepnieks, J.; Peavy, D.; Frank, B.; Rabkin, R.

1989-01-01

The kidney is a major site for insulin metabolism, but the enzymes involved and the products generated have not been established. To examine the products, we have perfused rat kidneys with insulin specifically iodinated on either the A14 or the B26 tyrosine. Labeled material from both the perfusate and kidney extract was examined by Sephadex G50 and high-performance liquid chromatography (HPLC). In perfusate from a filtering kidney, 22% of the insulin-sized material was not intact insulin on HPLC. With the nonfiltering kidney, 10.6% was not intact insulin. Labeled material from HPLC was sulfitolyzed and reinjected on HPLC. By use of 125 I-iodo(A14)-insulin, almost all the degradation products contained an intact A-chain. By use of 125 I-iodo(B26)-insulin, several different B-chain-cleaved products were obtained. The material extracted from the perfused kidney was different from perfusate products but similar to intracellular products from hepatocytes, suggesting that cellular metabolism by kidney and liver are similar. The major intracellular product had characteristics consistent with a cleavage between the B16 and B17 amino acids. This product and several of the perfusate products are also produced by insulin protease suggesting that this enzyme is involved in the degradation of insulin by kidney

A thermodynamic approach to choosing pervaporatives membranes

Directory of Open Access Journals (Sweden)

Mahacine Amrani

2006-09-01

Full Text Available This work describes separating a mixture of several components obtained as a product of methyl polymethyl metha- crylate (PMMA thermo-degradation. It was aimed at purifying methyl methacrylate monomer (MMA obtained by 95% mass thermal degradation to reach 99.5% maximum pervaporation concentration. This work studied the theory of pervaporation and applying the main thermodynamic criteria for choosing suitable polymer membranes for separating the MMA/PRP/ISB mixture. Such thermodynamic criteria were based on monomer interaction with and solubility on the membrane. The advantage of using this separation technique lies mainly in the fact that this method has low energy consumption compared to other processes, such as distillation or crystallisation.

In-Vitro gas production technique as for feed evaluation: volume of gas production and feed degradability

International Nuclear Information System (INIS)

Asih Kurniawati

2007-01-01

In-vitro gas production technique can be used to predict feed quality. The effect of molasses supplementation as a source of degradable carbohydrate to protein source red clover silage has been done using this technique. Data showed there were positive correlation between total volume gas produced and feed degradability (r = 0.96), between total volume gas produced and microbial biomass (r = 0,96). Dry matter degradability, dry matter degraded, microbial biomass production and efficiency of nitrogen utilization, highly significant (P<0,01) increased due to increasing of degradable carbohydrate. The addition of 0.3 g molasses gave the best result whereas the addition of 0.15 g and 0.225 g have better effect than 0.0625 g molasses addition and red clover only. This result suggested that In-vitro production technique can be used as tool for feed evaluation. (author)

Report: More Information Is Needed On Toxaphene Degradation Products

Science.gov (United States)

Report #2006-P-00007, Dec 16, 2005. Toxaphene in the environment changes, or degrades. The degradation products are different from the original toxaphene in chemical composition and how they appear to testing instruments, so they could go unreported.

Gamma radiolytic degradation of 4-chlorophenol determination of degraded products with HPLC and GC-MS

International Nuclear Information System (INIS)

Butt, S.B.; Masood, M.N.

2007-01-01

Contamination by chlorophenols of surface water and groundwater is an emerging issue in environmental science and engineering. After their usage as pesticide, herbicide and disinfectant, these organic compounds subsequently enter the aquatic environment through a number of routes. Some of the chlorophenols are slightly biodegradable, while others are more persistent and mobile in the aquatic environment especially chlorophenols. Gamma radiolytic degradation is one of advance oxidation process that has been thought to be one of the promising treatments to deal with this problem. This radiolytic study was carried out in methanolic 4-CP (4-chlorophenol) samples. Among several factors effecting radiolytic degradation of 4-CP, dose and concentration are important that were evaluated under atmospheric conditions. A degradation yield (G -value) for 4- CP of 0.38 and 1.35 was achieved in 20 and 100 mg/dm/sup 3/ solution. It was observed that degradation yield decreases with increasing 4-CP concentration. Gamma radiolysis produce free radicals in solvent which further react with 4-CP molecules to generate different products. The identification of degradation products was proposed using HPLC and GC-MS. (author)

Oxygen activation at the plasma membrane: relation between superoxide and hydroxyl radical production by isolated membranes.

Science.gov (United States)

Heyno, Eiri; Mary, Véronique; Schopfer, Peter; Krieger-Liszkay, Anja

2011-07-01

Production of reactive oxygen species (hydroxyl radicals, superoxide radicals and hydrogen peroxide) was studied using EPR spin-trapping techniques and specific dyes in isolated plasma membranes from the growing and the non-growing zones of hypocotyls and roots of etiolated soybean seedlings as well as coleoptiles and roots of etiolated maize seedlings. NAD(P)H mediated the production of superoxide in all plasma membrane samples. Hydroxyl radicals were only produced by the membranes of the hypocotyl growing zone when a Fenton catalyst (FeEDTA) was present. By contrast, in membranes from other parts of the seedlings a low rate of spontaneous hydroxyl radical formation was observed due to the presence of small amounts of tightly bound peroxidase. It is concluded that apoplastic hydroxyl radical generation depends fully, or for the most part, on peroxidase localized in the cell wall. In soybean plasma membranes from the growing zone of the hypocotyl pharmacological tests showed that the superoxide production could potentially be attributed to the action of at least two enzymes, an NADPH oxidase and, in the presence of menadione, a quinone reductase.

Achievements of European projects on membrane reactor for hydrogen production

NARCIS (Netherlands)

di Marcoberardino, G.; Binotti, M.; Manzolini, G.; Viviente, J.L.; Arratibel Plazaola, A.; Roses, L.; Gallucci, F.

2017-01-01

Membrane reactors for hydrogen production can increase both the hydrogen production efficiency at small scale and the electric efficiency in micro-cogeneration systems when coupled with Polymeric Electrolyte Membrane fuel cells. This paper discusses the achievements of three European projects

Linear equations on thermal degradation products of wood chips in alkaline glycerol

International Nuclear Information System (INIS)

Demirbas, Ayhan

2004-01-01

Wood chips of 0.3 and 2 mm depth from poplar and spruce wood samples, respectively, were degraded by using glycerol as a solvent and alkaline glycerol with and without Na 2 CO 3 and NaOH catalysts at different degradation temperatures: 440, 450, 460, 470, 480, 490 and 500 K. By products from the degradation processes of the ligno celluloses include lignin degradation products. Lignin and its degradation products have fuel values. The total degradation degree and cellulose degradation of the wood chips were determined to find the relationship, if any, between the yields of total degradation degree (YTD) and degradation temperature (T). There is a good linear relationship between YTD or the yields of cellulose degradation (YCD) and T (K). For the wood samples, the regression equations from NaOH (10%) catalytic runs for 0.3 mm x 15 mm x 15 mm chip size are: For poplar wood: (YTD=0.7250T-267.507) (YCD=0.1736T-71.707) For spruce wood: (YTD=0.2650T-105.979) (YCD=0.0707T-27.507) For Eqs., the square of the correlation coefficient (r 2 ) were 0.9841, 0.9496, 0.9839 and 0.9447, respectively

Identification of Degradation Products of Lincomycin and Iopromide by Electron Beam Irradiation

International Nuclear Information System (INIS)

Cha, Yongbyoung; Ham, Hyunsun; Myung, Seungwoon

2013-01-01

Lincomycin and Iopromide are major species among the Pharmaceuticals and Personal Care Products (PPCPs) from four major rivers in Korea. The structure characterization of six lincomycin's and two iopromide's degradation products formed under the irradiation of electron beam was performed, and the degradation efficiency as a function of the various irradiation dose and sample concentration was investigated. Electron beam (10 MeV, 0.5 mA and 5 kW) experiments for the structural characterization of the degradation products, which is fortified with lincomycin, were performed at the dose of 10 kGy. The separation of its degradation products and lincomycin was carried by C18 column (2.1 Χ 100 mm, 3.5 μm), using gradient elution with 20 mM ammonium acetate and acetonitrile. The structures of degradation products of lincomycin and iopromide were proposed by interpretation of mass spectra and chromatograms by LC/MS/MS, and also the mass fragmentation pathways of mass spectra in tandem mass spectrometry were proposed. The experiments of the degradation efficiency as a function of the irradiation dose intensity and the initial concentration of lincomycin in aqueous environment were performed, and higher dose of electron beam and lower concentration was observed the increased degradation efficiency

Radiation degradation-adsorption treatment of some toxic dyes present in wastewater

International Nuclear Information System (INIS)

El-Kelesh, N.A.; Dessouki, A.M.; Amer, S.I.

2002-01-01

The radiolysis or three toxic dyes, viz. Reactive Yellow 3, Reactive Black 39, and Basic Blue 26, was investigated as a function of the dye concentration, pH, irradiation dose and dose rate. The radiolytic degradation was more pronounced with Reactive yellow 3 and Reactive Black 39 than with Basic Blue 26. The degree of degradation could be increased by combining the irradiation procedure with the conventional treatment, such as addition of oxygen or hydrogen peroxide; addition of nitrogen, on the other hand, resulted in no change. A pH drop was observed and tentatively attributed to the degradation of the dye molecules to lower molecular weight compounds such as organic acids. The primary radiolysis products as well as the secondary products are responsible for the degradation of the dye chromophore. Experiments with the adsorption or exchange of the dyes on GAC, some ion exchange resins and polymeric membranes were carried out to find that the polymeric membranes have the highest adsorption capacity for the pollutants except the basic dye. The combined treatment by irradiation and adsorption resulted in a complete removal of the toxic dyes in question

Performance Degradation Tests of Phosphoric Acid Doped PBI Membrane Based High Temperature PEM Fuel Cells

DEFF Research Database (Denmark)

Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

2014-01-01

Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation. Continuous tests with H2 and simulated reformate which was composed...... of H2, water steam and methanol as the fuel were performed on both single cells. 12-h-startup/12-h-shutdown dynamic tests were performed on the first single cell with pure dry H2 as the fuel and on the second single cell with simulated reformate as the fuel. Along with the tests electrochemical...... techniques such as polarization curves and electrochemical impedance spectroscopy (EIS) were employed to study the degradation mechanisms of the fuel cells. Both single cells showed an increase in the performance in the H2 continuous tests, because of a decrease in the ORR kinetic resistance probably due...

Development of a mixed-conductive ceramic membrane for syngas production

International Nuclear Information System (INIS)

Etchegoyen, G.

2005-10-01

Natural gas conversion into syngas (H 2 +CO) is very attractive for hydrogen and clean fuel production via GTL technology by providing an alternative to oil products and reducing greenhouse gas emission. Syngas production, using a mixed ionic-electronic conducting ceramic membrane, is thought to be particularly promising. The purpose of this PhD thesis was to develop this type of membrane. Mixed-conducting oxide was synthesized, characterized and then, shaped via tape casting and co-sintered in order to obtain multilayer membranes with controlled architectures and microstructures. Oxygen permeation fluxes were measured with a specific device to evaluate membrane performances. As a result, the optimisation of architecture and microstructure made it possible to increase oxygen permeation flux by a factor 30. Additional researches were focused on the oxide composition in order to achieve higher dimensional stability. (author)

Degradation of Histamine by Lactobacillus plantarum Isolated from Miso Products.

Science.gov (United States)

Kung, Hsien-Feng; Lee, Yi-Chen; Huang, Ya-Ling; Huang, Yu-Ru; Su, Yi-Cheng; Tsai, Yung-Hsiang

2017-10-01

Histamine is a toxic chemical and is the causative agent of food poisoning. This foodborne toxin may be degraded by the oxidative deamination activity of certain microorganisms. In this study, we isolated four histamine-degrading Lactobacillus plantarum bacteria from miso products. Among them, L. plantarum D-103 exhibited 100% degradation of histamine in de Man Rogosa Sharpe (MRS) broth containing 50 ppm of histamine after 24 h of incubation at 30°C. The optimal growth, histamine oxidase, and histamine-degrading activity of L. plantarum D-103 were observed in histamine MRS broth at pH 7.0, 3% NaCl, and 30°C. It also exhibited tolerance to broad ranges of pH (4 to 10) and salt concentrations (0 to 12%) in histamine MRS broth. Therefore, the histamine-degrading L. plantarum D-103 might be used as an additive culture to prevent histamine accumulation in miso products during fermentation.

Production of membrane proteins without cells or detergents.

Science.gov (United States)

Rajesh, Sundaresan; Knowles, Timothy; Overduin, Michael

2011-04-30

The production of membrane proteins in cellular systems is besieged by several problems due to their hydrophobic nature which often causes misfolding, protein aggregation and cytotoxicity, resulting in poor yields of stable proteins. Cell-free expression has emerged as one of the most versatile alternatives for circumventing these obstacles by producing membrane proteins directly into designed hydrophobic environments. Efficient optimisation of expression and solubilisation conditions using a variety of detergents, membrane mimetics and lipids has yielded structurally and functionally intact membrane proteins, with yields several fold above the levels possible from cell-based systems. Here we review recently developed techniques available to produce functional membrane proteins, and discuss amphipols, nanodisc and styrene maleic acid lipid particle (SMALP) technologies that can be exploited alongside cell-free expression of membrane proteins. Copyright © 2010 Elsevier B.V. All rights reserved.

Radiation degradation and crosslinking of polytetrafluoroethylene and its application

International Nuclear Information System (INIS)

Wu Guozhong; Wang Mouhua; Tang Zhongfeng

2009-01-01

Polytetrafluoroethylene (PTFE) is a high-performance engineering plastic and known as a typical material of radiation degradation. PTFE can be degraded by radiation under various conditions and PTFE micro-powder is usually fabricated by a combination of radiation and milling. PTFE can also be crosslinked by irradiation in the melt state (330∼340 degree C). The materials can be applied as a special additive due to its excellent wear resistance. Crosslinked PTFE may also be applied in lithography and fuel cell membrane in the future. In this paper, history and application of PTFE degradation and crosslinking products are reviewed. (authors)

A practical method for measuring the ion exchange capacity decrease of hydroxide exchange membranes during intrinsic degradation

Science.gov (United States)

Kreuer, Klaus-Dieter; Jannasch, Patric

2018-01-01

In this work we present a practical thermogravimetric method for quantifying the IEC (ion exchange capacity) decrease of hydroxide exchange membranes (HEMs) during intrinsic degradation mainly occurring through nucleophilic attack of the anion exchanging group by hydroxide ions. The method involves measuring weight changes under controlled temperature and relative humidity. These conditions are close to these in a fuel cell, i.e. the measured degradation rate includes all effects originating from the polymeric structure, the consumption of hydroxide ions and the release of water. In particular, this approach involves no added solvents or base, thereby avoiding inaccuracies that may arise in other methods due to the presence of solvents (other than water) or co-ions (such as Na+ or K+). We demonstrate the method by characterizing the decomposition of membranes consisting of poly(2,6-dimethyl-1,4-phenylene oxide) functionalized with trimethyl-pentyl-ammonium side chains. The decomposition rate is found to depend on temperature, relative humidity RH (controlling the hydration number λ) and the total water content (controlled by the actual IEC and RH).

Development of a mixed-conductive ceramic membrane for syngas production; Developpement d'une membrane ceramique conductrice mixte pour la production de gaz de synthese

Energy Technology Data Exchange (ETDEWEB)

Etchegoyen, G

2005-10-15

Natural gas conversion into syngas (H{sub 2}+CO) is very attractive for hydrogen and clean fuel production via GTL technology by providing an alternative to oil products and reducing greenhouse gas emission. Syngas production, using a mixed ionic-electronic conducting ceramic membrane, is thought to be particularly promising. The purpose of this PhD thesis was to develop this type of membrane. Mixed-conducting oxide was synthesized, characterized and then, shaped via tape casting and co-sintered in order to obtain multilayer membranes with controlled architectures and microstructures. Oxygen permeation fluxes were measured with a specific device to evaluate membrane performances. As a result, the optimisation of architecture and microstructure made it possible to increase oxygen permeation flux by a factor 30. Additional researches were focused on the oxide composition in order to achieve higher dimensional stability. (author)

Oxidative degradation property of the proton-exchange membranes based on fluorinated polymer using radiation-induced grafting

International Nuclear Information System (INIS)

Mitani, N.; Muto, F.; Fujii, K.; Sato, Y.; Kakigi, T.; Matsuura, A.; Li Jingye; Miura, T.; Oshima, A.; Washio, M.

2006-01-01

To grow popularity of polymer electrolyte fuel cells (PEFCs), it is important that the life-time of FC will be evaluated. In the PEFCs operation, the oxygenated water would be produced by fuel gases crossover reaction. Moreover, the metal ions such as Fe 2+ would dissolve from piping and humidification bubblers in FC systems. As the results, the dissolved metal ions catalyze with oxygenated water, and then active oxidative radicals such as hydroxy and hydroperoxy radicals are induced by Fenton reaction. The oxidative radicals have considered one of the reasons of deterioration of FC performance. In our previous study, the partial-fluorinated sulfonic acid membranes based on crosslinked PTFE (sulfonated RX-PTFE) have been fabricated by pre EB-grafting method. In this study, in order to evaluate the chemical durability exerted on the PEFC performance of sulfonated RX-PTFE, we carried out the accelerated degradation test by Fenton reaction. The test conditions were 6 vol% H 2 O 2 with 5 ppm Fe 2+ solution at 60 degree C. The properties of sulfonated RX-PTFE before and after degradation tests were measured by means of X-ray photoelectron spectroscopy (XPS) and other methods. According to oxidative degradation test, the sulfonated RX-PTFE with higher crosslinking density of main chain became hard to deteriorate. On the contrary, the higher grafting yields became easy to degrade. It is suggested that the oxidative degradation would be greatly influenced to the grafted chain length and crosslinking density of main chain. From XPS after Fenton treated sulfonated RX-PTFE, the signal of S 2p and S 2s was disappeared. And also, by TGA and TG-MS analysis, it was found that the reduction of grafted chains was taken place. Furthermore, the crosslinked PTFE chains may be degraded through the reduction of grafted chain. The PEFC operation tests of sulfonated RX-PTFE before and after degradation tests were carried out. When the weight loss of sulfonated RX-PTFE was almost the same

Enzymatic degradation behavior and cytocompatibility of silk fibroin-starch-chitosan conjugate membranes

Energy Technology Data Exchange (ETDEWEB)

Baran, Erkan T., E-mail: erkantur@metu.edu.tr; Tuzlakoglu, Kadriye, E-mail: kadriye@dep.uminho.pt; Mano, Joao F., E-mail: jmano@dep.uminho.pt; Reis, Rui L., E-mail: rgreis@dep.uminho.pt

2012-08-01

The objective of this study was to investigate the influence of silk fibroin and oxidized starch conjugation on the enzymatic degradation behavior and the cytocompatability of chitosan based biomaterials. The tensile stress of conjugate membranes, which was at 50 Megapascal (MPa) for the lowest fibroin and starch composition (10 weight percent (wt.%)), was decreased significantly with the increased content of fibroin and starch. The weight loss of conjugates in {alpha}-amylase was more notable when the starch concentration was the highest at 30 wt.%. The conjugates were resistant to the degradation by protease and lysozyme except for the conjugates with the lowest starch concentration. After 10 days of cell culture, the proliferation of osteoblast-like cells (SaOS-2) was stimulated significantly by higher fibroin compositions and the DNA synthesis on the conjugate with the highest fibroin (30 wt.%) was about two times more compared to the native chitosan. The light microscopy and the image analysis results showed that the cell area and the lengths were decreased significantly with higher fibroin/chitosan ratio. The study proved that the conjugation of fibroin and starch with the chitosan based biomaterials by the use of non-toxic reductive alkylation crosslinking significantly improved the cytocompatibility and modulated the biodegradation, respectively. - Highlights: Black-Right-Pointing-Pointer Silk fibroin, starch and chitosan conjugates were prepared by reductive alkylation. Black-Right-Pointing-Pointer The enzymatic biodegradation and the cytocompatibility of conjugates were tested. Black-Right-Pointing-Pointer The conjugate with 30% starch composition was degraded by {alpha}-amylase significantly. Black-Right-Pointing-Pointer Higher starch composition in conjugates prevented protease and lysozyme degradation. Black-Right-Pointing-Pointer Fibroin incorporation effectively increased the cell proliferation of conjugates.

Degradation of chitosan hydrogel dispersed in dilute carboxylic acids by solution plasma and evaluation of anticancer activity of degraded products

Science.gov (United States)

Chokradjaroen, Chayanaphat; Rujiravanit, Ratana; Theeramunkong, Sewan; Saito, Nagahiro

2018-01-01

Chitosan is a polysaccharide that has been extensively studied in the field of biomedicine, especially its water-soluble degraded products called chitooligosaccharides (COS). In this study, COS were produced by the degradation of chitosan hydrogel dispersed in a dilute solution (i.e., 1.55 mM) of various kinds of carboxylic acids using a non-thermal plasma technology called solution plasma (SP). The degradation rates of chitosan were influenced by the type of carboxylic acids, depending on the interaction between chitosan and each carboxylic acid. After SP treatment, the water-soluble degraded products containing COS could be easily separated from the water-insoluble residue of chitosan hydrogel by centrifugation. The production yields of the COS were mostly higher than 55%. Furthermore, the obtained COS products were evaluated for their inhibitory effect as well as their selectivity against human lung cancer cells (H460) and human lung normal cells (MRC-5).

Bio-Gas production from municipal sludge waste using anaerobic membrane bioreactor

International Nuclear Information System (INIS)

Lee, Y. H.; Lee, S.

2009-01-01

A laboratory scale anaerobic membrane bioreactor (AnMBR) system for the bio-methane gas production was operated for 60 days with municipal sludge wastes as a sole carbon source. The AnMRR system utilized the external cross-flow membrane module and was equipped with on-line data acquisition which enables continuous monitoring of the performance of both bioreactor and membrane through the analyses of pH, temperature, gas production; permeate flow rate, and transmembrane pressure (TMP). Such a configuration also provides an efficient tool to study rapid variations of monitoring membrane pressure (TMP). (Author)

Biogas Production from Citrus Waste by Membrane Bioreactor

Directory of Open Access Journals (Sweden)

Rachma Wikandari

2014-08-01

Full Text Available Rapid acidification and inhibition by d-limonene are major challenges of biogas production from citrus waste. As limonene is a hydrophobic chemical, this challenge was encountered using hydrophilic polyvinylidine difluoride (PVDF membranes in a biogas reactor. The more sensitive methane-producing archaea were encapsulated in the membranes, while freely suspended digesting bacteria were present in the culture as well. In this membrane bioreactor (MBR, the free digesting bacteria digested the citrus wastes and produced soluble compounds, which could pass through the membrane and converted to biogas by the encapsulated cell. As a control experiment, similar digestions were carried out in bioreactors containing the identical amount of just free cells. The experiments were carried out in thermophilic conditions at 55 °C, and hydraulic retention time of 30 days. The organic loading rate (OLR was started with 0.3 kg VS/m3/day and gradually increased to 3 kg VS/m3/day. The results show that at the highest OLR, MBR was successful to produce methane at 0.33 Nm3/kg VS, while the traditional free cell reactor reduced its methane production to 0.05 Nm3/kg VS. Approximately 73% of the theoretical methane yield was achieved using the membrane bioreactor.

A Bayesian approach to degradation-based burn-in optimization for display products exhibiting two-phase degradation patterns

International Nuclear Information System (INIS)

Yuan, Tao; Bae, Suk Joo; Zhu, Xiaoyan

2016-01-01

Motivated by the two-phase degradation phenomena observed in light displays (e.g., plasma display panels (PDPs), organic light emitting diodes (OLEDs)), this study proposes a new degradation-based burn-in testing plan for display products exhibiting two-phase degradation patterns. The primary focus of the burn-in test in this study is to eliminate the initial rapid degradation phase, while the major purpose of traditional burn-in tests is to detect and eliminate early failures from weak units. A hierarchical Bayesian bi-exponential model is used to capture two-phase degradation patterns of the burn-in population. Mission reliability and total cost are introduced as planning criteria. The proposed burn-in approach accounts for unit-to-unit variability within the burn-in population, and uncertainty concerning the model parameters, mainly in the hierarchical Bayesian framework. Available pre-burn-in data is conveniently incorporated into the burn-in decision-making procedure. A practical example of PDP degradation data is used to illustrate the proposed methodology. The proposed method is compared to other approaches such as the maximum likelihood method or the change-point regression. - Highlights: • We propose a degradation-based burn-in test for products with two-phase degradation. • Mission reliability and total cost are used as planning criteria. • The proposed burn-in approach is built within the hierarchical Bayesian framework. • A practical example was used to illustrate the proposed methodology.

A biodegradable vascularizing membrane: a feasibility study.

Science.gov (United States)

Kaushiva, Anchal; Turzhitsky, Vladimir M; Darmoc, Marissa; Backman, Vadim; Ameer, Guillermo A

2007-09-01

Regenerative medicine and in vivo biosensor applications require the formation of mature vascular networks for long-term success. This study investigated whether biodegradable porous membranes could induce the formation of a vascularized fibrous capsule and, if so, the effect of degradation kinetics on neovascularization. Poly(l-lactic acid) (PLLA) and poly(dl-lactic-co-glycolic) acid (PLGA) membranes were created by a solvent casting/salt leaching method. Specifically, PLLA, PLGA 75:25 and PLGA 50:50 polymers were used to vary degradation kinetics. The membranes were designed to have an average 60mum pore diameter, as this pore size has been shown to be optimal for inducing blood vessel formation around nondegradable polymer materials. Membrane samples were imaged by scanning electron microscopy at several time points during in vitro degradation to assess any changes in pore structure. The in vivo performance of the membranes was assessed in Sprague-Dawley rats by measuring vascularization within the fibrous capsule that forms adjacent to implants. The vascular density within 100microm of the membranes was compared with that seen in normal tissue, and to that surrounding the commercially available vascularizing membrane TheraCyte. The hemoglobin content of tissue containing the membranes was measured by four-dimensional elastic light scattering as a novel method to assess tissue perfusion. Results from this study show that slow-degrading membranes induce greater amounts of neovascularization and a thinner fibrous capsule relative to fast degrading membranes. These results may be due both to an initially increased number of macrophages surrounding the slower degrading membranes and to the maintenance of their initial pore structure.

Possible Appearance of Degradation Products of Paraquat in Crops

Energy Technology Data Exchange (ETDEWEB)

Slade, P. [Imperial Chemical Industries LTD., Jealott' s Hill Research Station, Bracknell, Berks. (United Kingdom)

1966-05-15

Chemical analysis has established that residue levels of paraquat in crops harvested after use of the chemical are at such a low level as to constitute no hazard to the consuming public. (Paraquat dichloride is 1,1'-dimethyl-4,4'-bipyridylium dichloride). There remained the possibility that toxic metabolites or other conversion products of paraquat might appear in crops. This paper is concerned with attempts to evaluate this possibility, and demonstrates that no hazard arises from the formation of degradation products. It has been shown, using paraquat labelled with {sup 14}C in the methyl groups and in the pyridine nuclei, that the chemical is not metabolically degraded in plants. However, photochemical degradation of paraquat can occur on the surface of leaves in sunlight. In vitro experiments involving ultra-violet irradiation of aqueous solutions of {sup 14}C-paraquat have shown that 4-carboxy-1-methylpyridinium chloride and methylamine hydrochloride are the only products formed in significant amount in the photochemical degradation. Paper chromatography and isotope dilution have shown that these products are formed on leaves of plants treated with {sup 14}C-paraquat (mostly after the plants are dead). Whole plant radioautography has established that 4-carboxy-1-{sup 14}C methylpyridinium chloride is not translocated at all from the dead leaves on which it is formed and certainly this compound will not appear in harvested crops. This has been confirmed in an experiment in which {sup 14}C-paraquat was used to desiccate the tops of potato plants before harvesting the tubers. All the radioactivity subsequently found in the tubers could be accounted for as paraquat (level 0.08 ppm). There was no evidence for the presence of significant amounts of other radioactive compounds in the tubers, even though chromatography of extracts of the desiccated plants showed that photochemical degradation products were formed on the leaves: these were not translocated into the

Photocatalytic degradation of dairy effluent using AgTiO2 nanostructures/polyurethane nanofiber membrane

DEFF Research Database (Denmark)

Kanjwal, Muzafar Ahmad; Barakat, Nasser A.M.; Chronakis, Ioannis S.

2015-01-01

Dairy effluent (DE) is environmentally toxic and needs special attention. Photocatalytic degradation of DE was studied using novel polyurethane (PU)-based membranes. Typically, silver-titanium dioxide nanofibers (AgTiO2 NFs) and silver-titanium dioxide nanoparticles (AgTiO2 NPs) were individually...... incorporated in PU electrospun nanofibers to overcome the mandatory sophisticated separation of the nanocatalysts, which can create a secondary pollution, after the treatment process. These nanomembranes were characterized in SEM, TEM, XRD and UV studies. The polymeric electrospun nanofibers were smooth...

The sources, fate, and toxicity of chemical warfare agent degradation products.

Science.gov (United States)

Munro, N B; Talmage, S S; Griffin, G D; Waters, L C; Watson, A P; King, J F; Hauschild, V

1999-01-01

We include in this review an assessment of the formation, environmental fate, and mammalian and ecotoxicity of CW agent degradation products relevant to environmental and occupational health. These parent CW agents include several vesicants: sulfur mustards [undistilled sulfur mustard (H), sulfur mustard (HD), and an HD/agent T mixture (HT)]; nitrogen mustards [ethylbis(2-chloroethyl)amine (HN1), methylbis(2-chloroethyl)amine (HN2), tris(2-chloroethyl)amine (HN3)], and Lewisite; four nerve agents (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX), tabun (GA), sarin (GB), and soman (GD)); and the blood agent cyanogen chloride. The degradation processes considered here include hydrolysis, microbial degradation, oxidation, and photolysis. We also briefly address decontamination but not combustion processes. Because CW agents are generally not considered very persistent, certain degradation products of significant persistence, even those that are not particularly toxic, may indicate previous CW agent presence or that degradation has occurred. Of those products for which there are data on both environmental fate and toxicity, only a few are both environmentally persistent and highly toxic. Major degradation products estimated to be of significant persistence (weeks to years) include thiodiglycol for HD; Lewisite oxide for Lewisite; and ethyl methyl phosphonic acid, methyl phosphonic acid, and possibly S-(2-diisopropylaminoethyl) methylphosphonothioic acid (EA 2192) for VX. Methyl phosphonic acid is also the ultimate hydrolysis product of both GB and GD. The GB product, isopropyl methylphosphonic acid, and a closely related contaminant of GB, diisopropyl methylphosphonate, are also persistent. Of all of these compounds, only Lewisite oxide and EA 2192 possess high mammalian toxicity. Unlike other CW agents, sulfur mustard agents (e.g., HD) are somewhat persistent; therefore, sites or conditions involving potential HD contamination should include an

Effects of cellulosic degradation products on uranium sorption in the geosphere

International Nuclear Information System (INIS)

Baston, G.M.N.; Berry, J.A.; Bond, K.A.; Boult, K.A.; Brownsword, M.; Linklater, C.M.

1994-01-01

The current design concept for intermediate- and some low-level radioactive waste disposal in the UK involves emplacement in a cementitious repository deep underground. The movement of radionuclides away from such a repository through the host rock formation towards the biosphere is expected to be retarded to a significant degree by sorption processes. One major issue being studied is the effect on uranium sorption of degradation products arising from organic waste matter, especially cellulosic materials. The sorption of uranium could be reduced by degradation products, either because of complexation, or through the organic materials competing for sorption sites. Because of the complexity of authentic degradation products, work has also been carried out using gluconate and iso-saccharinate as well-characterised simulants. In the presence of high concentrations of either the authentic or simulated degradation products, significant reductions in uranium sorption have been observed. However, in the presence of lower concentrations of these organic materials, such as would be present in the repository, sorption was reduced at most by only a small margin and, in some cases, the results suggested a slight increase. ((orig.))

Effects of cellulosic degradation products on uranium sorption in the geosphere

Energy Technology Data Exchange (ETDEWEB)

Baston, G.M.N. (AEA Technology, Harwell, Didcot, Oxon OX11 0RA (United Kingdom)); Berry, J.A. (AEA Technology, Harwell, Didcot, Oxon OX11 0RA (United Kingdom)); Bond, K.A. (AEA Technology, Harwell, Didcot, Oxon OX11 0RA (United Kingdom)); Boult, K.A. (AEA Technology, Harwell, Didcot, Oxon OX11 0RA (United Kingdom)); Brownsword, M. (AEA Technology, Harwell, Didcot, Oxon OX11 0RA (United Kingdom)); Linklater, C.M. (AEA Technology, Harwell, Didcot, Oxon OX11 0RA (United Kingdom))

1994-10-01

The current design concept for intermediate- and some low-level radioactive waste disposal in the UK involves emplacement in a cementitious repository deep underground. The movement of radionuclides away from such a repository through the host rock formation towards the biosphere is expected to be retarded to a significant degree by sorption processes. One major issue being studied is the effect on uranium sorption of degradation products arising from organic waste matter, especially cellulosic materials. The sorption of uranium could be reduced by degradation products, either because of complexation, or through the organic materials competing for sorption sites. Because of the complexity of authentic degradation products, work has also been carried out using gluconate and iso-saccharinate as well-characterised simulants. In the presence of high concentrations of either the authentic or simulated degradation products, significant reductions in uranium sorption have been observed. However, in the presence of lower concentrations of these organic materials, such as would be present in the repository, sorption was reduced at most by only a small margin and, in some cases, the results suggested a slight increase. ((orig.))

ANALYTICAL METHOD DEVELOPMENT FOR ALACHLOR ESA AND OTHER ACETANILIDE HERBICIDE DEGRADATION PRODUCTS

Science.gov (United States)

In 1998, USEPA published a Drinking Water Contaminant Candidate List (CCL) of 50 chemicals and 10 microorganisms. "Alachlor ESA and other acetanilide herbicide degradation products" is listed on the the 1998 CCL. Acetanilide degradation products are generally more water soluble...

Pressure retarded osmosis for energy production: membrane materials and operating conditions.

Science.gov (United States)

Kim, H; Choi, J-S; Lee, S

2012-01-01

Pressure retarded osmosis (PRO) is a novel membrane process to produce energy. PRO has the potential to convert the osmotic pressure difference between fresh water (i.e. river water) and seawater to electricity. Moreover, it can recover energy from highly concentrated brine in seawater desalination. Nevertheless, relatively little research has been undertaken for fundamental understanding of the PRO process. In this study, the characteristics of the PRO process were examined using a proof-of-concept device. Forward osmosis (FO), reverse osmosis (RO), and nanofiltration (NF) membranes were compared in terms of flux rate and concentration polarization ratio. The results indicated that the theoretical energy production by PRO depends on the membrane type as well as operating conditions (i.e. back pressure). The FO membrane had the highest energy efficiency while the NF membrane had the lowest efficiency. However, the energy production rate was low due to high internal concentration polarization (ICP) in the PRO membrane. This finding suggests that the control of the ICP is essential for practical application of PRO for energy production.

Forced degradation studies of lansoprazole using LC-ESI HRMS and 1 H-NMR experiments: in vitro toxicity evaluation of major degradation products.

Science.gov (United States)

Shankar, G; Borkar, R M; Suresh, U; Guntuku, L; Naidu, V G M; Nagesh, N; Srinivas, R

2017-07-01

Regulatory agencies from all over the world have set up stringent guidelines with regard to drug degradation products due to their toxic effects or carcinogenicity. Lansoprazole, a proton-pump inhibitor, was subjected to forced degradation studies as per ICH guidelines Q1A (R2). The drug was found to degrade under acidic, basic, neutral hydrolysis and oxidative stress conditions, whereas it was found to be stable under thermal and photolytic conditions. The chromatographic separation of the drug and its degradation products were achieved on a Hiber Purospher, C18 (250 × 4.6 mm, 5 μ) column using 10 mM ammonium acetate and acetonitrile as a mobile phase in a gradient elution mode at a flow rate of 1.0 ml/min. The eight degradation products (DP1-8) were identified and characterized by UPLC/ESI/HRMS with in-source CID experiments combined with accurate mass measurements. DP-1, DP-2 and DP-3 were formed in acidic, DP-4 in basic, DP-5 in neutral and DP-1, DP-6, DP-7 and DP-8 were in oxidation stress condition Among eight degradation products, five were hitherto unknown degradation products. In addition, one of the major degradation products, DP-2, was isolated by using semi preparative HPLC and other two, DP-6 and DP-7 were synthesized. The cytotoxic effect of these degradation products (DP-2, DP-6 and DP-7) were tested on normal human cells such as HEK 293 (embryonic kidney cells) and RWPE-1(normal prostate epithelial cells) by MTT assay. From the results of cytotoxicity, it was found that lansoprazole as well as its degradation products (DP-2, DP-6 and DP-7) were nontoxic up to 50-μM concentrations, and the latter showed slightly higher cytotoxicity when compared with that of lansoprazole. DNA binding studies using spectroscopic techniques indicate that DP-2, DP-6 and DP-7 molecules interact with ctDNA and may bind to its surface. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

On-Site Enzyme Production by Trichoderma asperellum for the Degradation of Duckweed

DEFF Research Database (Denmark)

Bech, Lasse; Herbst, Florian-Alexander; Grell, Morten Nedergaard

2015-01-01

The on-site production of cell wall degrading enzymes is an important strategy for the development of sustainable bio-refinery processes. This study concerns the optimization of production of plant cell wall-degrading enzymes produced by Trichoderma asperellum. A comparative secretome analysis...

Oxygen transport and degradation properties of high-temperature membranes for CO{sub 2}-free power plants; Sauerstofftransport und Degradationsverhalten von Hochtemperaturmembranen fuer CO{sub 2}-freie Kraftwerke

Energy Technology Data Exchange (ETDEWEB)

Schlehuber, Dominic

2010-07-01

This thesis deals with membranes for oxygen separation from air for high temperature application in fossil power plants within the scope of the oxyfuel-process. Different perovskite membrane materials (ABO3-ae) were investigated concerning the oxygen transport and their chemical stability under operation condition. The association between oxygen transport properties and both the thermodynamic boundary conditions as well as the material properties (membrane thickness and surface properties) was studied. One possibility to achieve higher oxygen fluxes through the membrane is to reduce the thickness. In this case the influence of surface processes on the overall permeation becomes noteworthy. The effect of different membrane surface modifications on the permeation rate was investigated. For example it could be confirmed, that a porous layer on the membrane surface significantly increases the permeation flux due to the compensation of surface exchange limitations. Beyond that, degradation processes during the operation under power plant condition were investigated. Special attention was attached to the influence of degradation on the permeation flux during long term operation. Thereby kinetic demixing of the membrane material was observed. (orig.)

Photocatalytic degradation of tetracycline by Ti-MCM-41 prepared at room temperature and biotoxicity of degradation products

Science.gov (United States)

Zhou, Kefu; Xie, Xiao-Dan; Chang, Chang-Tang

2017-09-01

Ti-doped MCM-41 with different Si/Ti molar ratios was prepared at room temperature to degrade tetracycline antibiotics in aqueous solution. The Ti was doped into the skeleton structure of MCM-41. The photocatalytic activity of Ti-doped MCM-41 was investigated. The optimal catalyst had Si/Ti molar ratio of 25 and over 99% removal of oxytetracycline in 150 min, and the removal could maintain 98% after 5 reuses. Ions and soluble organic matters in natural water affected the degradation reaction when Ti-doped MCM-41 was used to treat simulated wastewater of chicken farms. The degradation products of oxytetracycline, tetracycline and chlortetracycline were detected by Escherichia coli DH5α and HPLC-MS/MS. No intermediate product with higher toxicity was detected.

Extrusion: An environmentally friendly process for PEMFC membrane elaboration

Energy Technology Data Exchange (ETDEWEB)

Sanchez, J.-Y.; Iojoiu, C.; Marechal, M. [LEPMI, UMR 5631 CNRS-INPG-UJF, ENSEEG, BP 75, F-38402, Saint Martin d' Heres (France); Chabert, F.; El Kissi, N. [Rheologie, UMR 5520 CNRS-INPG-UJF, ENSHMG, BP 53, F-38041, Grenoble (France); Salomon, J.; Mercier, R. [LMOPS UMR CNRS 5041, BP 24, F-69390 Vernaison (France); Piffard, Y. [CNRS Universite de Nantes, Institut des Materiaux Jean Rouxel, UMR 6502, BP 32229, F-44322, Nantes Cedex 3 (France); Galiano, H. [CEA, Le Ripault Research Center, BP 16, F-37260, Monts (France)

2007-12-31

The paper deals with the use of extrusion to process PEMFC filled and unfilled membranes. Several routes including the sulfonation of filled and unfilled extruded membranes and the extrusion of filled and unfilled ionomers are reported. Thanks to the use of selected water-soluble aid process plasticizers, acid and alkaline forms of sulfonated polyethersulfone were, for the first time, successfully extruded. The extrusion process did not lead to any degradation of the ionomer performances. Decreasing the membrane cost while using environmentally friendly elaboration conditions, it should be helpful to an industrial production. In addition, avoiding filler sedimentation it should allow homogeneous composite membranes to be obtained. (author)

Anaerobic membrane bioreactors and the influence of space velocity and biomass concentration on methane production for liquid dairy manure

International Nuclear Information System (INIS)

Wallace, James M.; Safferman, Steven I.

2014-01-01

Two pilot-scale anaerobic membrane bioreactors (AnMBRs) and a control completely mixed digester (CMD) were constructed to evaluate the influence of space velocity and biomass concentration on methane production for sand separated dairy manure. A negative impact on methane production resulted with operating the AnMBR system at 972 μHz–2960 μHz but no impact was found when operating at 69 μHz and 312 μHz. Operating at 69 μHz–350 μHz is realistic for a field installation. Despite the higher biomass concentration, the methane production of the AnMBRs was nearly equal to the CMD. An AnMBR with 69 μHz was operated equivalent to a CMD by returning all permeate to the digester tank and removing excess biomass directly from the reactor tank resulting in a hydraulic retention time (HRT) equal to the solids retention time (SRT). When using sand separated dairy manure and an HRT (and equal SRT) of 12 d, both systems produced methane at an equal rate, suggesting that the pump/membrane system did not influence methane production. The most likely reason was mass transfer limitations of hydrolytic enzymes. Based on methane production and volatile fatty acids analysis, it appears the fermentable substrate available for degradation was similar. The AnMBR proved to have benefit as part of an integrated nutrient management system that produced water that is virtually free of particulate nutrients, especially phosphorus. This enables the irrigation of the water to crops that need nitrogen and the efficient movement of phosphorus, as a solid, to needed locations. - Highlights: • Manure AnMBRs with a high space velocity inhibit methane production. • Manure AnMBRs with a low space velocity perform similar to conventional digesters. • Decoupled HRT and SRT in manure AnMBRs do not increase methane production. • Ultrafiltration membranes effectively partitioned manure nutrients from the liquid. • Manure does not foul ultrafiltration membranes and require mild

Membrane Protein Production in Lactococcus lactis for Functional Studies.

Science.gov (United States)

Seigneurin-Berny, Daphne; King, Martin S; Sautron, Emiline; Moyet, Lucas; Catty, Patrice; André, François; Rolland, Norbert; Kunji, Edmund R S; Frelet-Barrand, Annie

2016-01-01

Due to their unique properties, expression and study of membrane proteins in heterologous systems remains difficult. Among the bacterial systems available, the Gram-positive lactic bacterium, Lactococcus lactis, traditionally used in food fermentations, is nowadays widely used for large-scale production and functional characterization of bacterial and eukaryotic membrane proteins. The aim of this chapter is to describe the different possibilities for the functional characterization of peripheral or intrinsic membrane proteins expressed in Lactococcus lactis.

Extracellular membrane vesicles in blood products-biology and clinical relevance

Directory of Open Access Journals (Sweden)

Emilija Krstova Krajnc

2016-01-01

Full Text Available Extracellular membrane vesicles are fragments shed from plasma membranes off all cell types that are undergoing apoptosis or are being subjected to various types of stimulation or stress.  Even in the process of programmed cell death (apoptosis, cell fall apart of varying size vesicles. They expose phosphatidylserine (PS on the outer leaflet of their membrane, and bear surface membrane antigens reflecting their cellular origin. Extracellular membrane vesicles have been isolated from many types of biological fluids, including serum, cerebrospinal fluid, urine, saliva, tears and conditioned culture medium. Flow cytometry is one of the many different methodological approaches that have been used to analyze EMVs. The method attempts to characterize the EMVs cellular origin, size, population, number, and structure. EMVs are present and accumulate in blood products (erythrocytes, platelets as well as in fresh frozen plasma during storage. The aim of this review is to highlight the importance of extracellular vesicles as a cell-to-cell communication system and the role in the pathogenesis of different diseases. Special emphasis will be given to the implication of extracellular membrane vesicles in blood products and their clinical relevance. Although our understanding of the role of  EMVs in disease is far from comprehensive, they display promise as biomarkers for different diseases in the future and also as a marker of quality and safety in the quality control of blood products.

Smart membranes for monitoring membrane based desalination processes

KAUST Repository

Laleg-Kirati, Taous-Meriem

2017-10-12

Various examples are related to smart membranes for monitoring membrane based process such as, e.g., membrane distillation processes. In one example, a membrane, includes a porous surface and a plurality of sensors (e.g., temperature, flow and/or impedance sensors) mounted on the porous surface. In another example, a membrane distillation (MD) process includes the membrane. Processing circuitry can be configured to monitor outputs of the plurality of sensors. The monitored outputs can be used to determine membrane degradation, membrane fouling, or to provide an indication of membrane replacement or cleaning. The sensors can also provide temperatures or temperature differentials across the porous surface, which can be used to improve modeling or control the MD process.

Production and application of cation/anion exchange membranes of high performance

International Nuclear Information System (INIS)

Xu Zhili; Tan Chunhong; Yang Xiangmin

1995-01-01

A third affiliated factory of our university has been established for the production in batches of cation/anion exchange membranes of high performance, trade marks of which are HF-1 and HF-2. Membrane products have been applied in various fields (including industries and research institutions) with great success

Solution phase and membrane immobilized iron-based free radical reactions: Fundamentals and applications for water treatment

Science.gov (United States)

Lewis, Scott Romak

Membrane-based separation processes have been used extensively for drinking water purification, wastewater treatment, and numerous other applications. Reactive membranes synthesized through functionalization of the membrane pores offer enhanced reactivity due to increased surface area at the polymer-solution interface and low diffusion limitations. Oxidative techniques utilizing free radicals have proven effective for both the destruction of toxic organics and non-environmental applications. Most previous work focuses on reactions in the homogeneous phase; however, the immobilization of reactants in membrane pores offers several advantages. The use of polyanions immobilized in a membrane or chelates in solution prevents ferric hydroxide precipitation at near-neutral pH, a common limitation of iron(Fe(II/III))-catalyzed hydrogen peroxide (H 2O2) decomposition. The objectives of this research are to develop a membrane-based platform for the generation of free radicals, degrade toxic organic compounds using this and similar solution-based reactions, degrade toxic organic compounds in droplet form, quantify hydroxyl radical production in these reactions, and develop kinetic models for both processes. In this study, a functionalized membrane containing poly(acrylic acid) (PAA) was used to immobilize iron ions and conduct free radical reactions by permeating H2O2 through the membrane. The membrane's responsive behavior to pH and divalent cations was investigated and modeled. The conversion of Fe(II) to Fe(III) in the membrane and its effect on the decomposition of hydrogen peroxide were monitored and used to develop kinetic models for predicting H2O2 decomposition in these systems. The rate of hydroxyl radical production, and hence contaminant degradation can be varied by changing the residence time, H2O2 concentration, and/or iron loading. Using these membrane-immobilized systems, successful removal of toxic organic compounds, such as pentachlorophenol (PCP), from water

Gamma irradiation prolongs the sea bass (Dicentrarchus labrax L) storage and delays the lipids membrane degradation

International Nuclear Information System (INIS)

Barkallah, Insaf; Mahjoub, Abdelmajid; Cheour, F.

2005-01-01

Sea bass have been submitted to gamma rays radiation at doses 0, 1, 2, 3 or 4 KGy at 0,087KGY/min rate and stored during 21 days at 1 0 C to evaluate the effects on the development of microorganisms as well as on the conservation and the degradation of membranes lipids Microbiological analysis has revealed only the presence of mesophils germs in muscles which are totally eliminated at dose 4 KGy. The presence of psychrophiles, halophiles, coliformes, fecaux and totals, Staphylococcus aureus and Clostridium sulfutoreducteurs has been noted in the visceres of sea bass. They are completely eliminated at dose 1KGy. Contents in nitrogen basic fowl (ABVT) and in trimethylamine (TMA), as well as the pH increase during storage of fish in relation with the reduction of phospholipids, the diminution of the degree of insaturation of the phospholipids and the free fat acidic fraction, and the increase of the report sterols on phospholipids. The irradiation to gamma rays allows to slow these changes and consequently reduced the deterioration of the sea bass. We conclude that the irradiation to gamma rays could have prolong the conservation of sea bass sea bass by preserving probably lipids membranes of the degradation and by inhibiting the development of microorganisms

Fouling in a MBR system with rotating membrane discs

DEFF Research Database (Denmark)

Jørgensen, Mads Koustrup; Bentzen, Thomas Ruby; Christensen, Morten Lykkegaard

concentrations and a clear effluent with no bacteria present in the permeate [1]. However, the process performance is limited by membrane fouling, which results in a lower productivity and higher energy demand and hence places demands for limitation of fouling and/or cleaning of the membranes. One way to do...... uses rotating ceramic membrane discs for creation of shear, which can be changed by controlling the membrane rotation speed of the membrane. Furthermore, the influence of shear on fouling is studied at different radii from the center of rotation, by dividing membranes into different concentric rings......Membrane bioreactors (MBR) are an attractive alternative solution for municipal and industrial wastewater treatment. The MBR, which is a combination of a bioreactor for sludge degradation and a membrane for separation, has the advantages of a low footprint, ability to handle high sludge...

Membrane processes in production of functional whey components

Directory of Open Access Journals (Sweden)

Lutfiye Yilmaz-Ersan

2009-12-01

Full Text Available In recent years, whey has been recognised as a major source of nutritional and functional ingredients for the food industry. Commercial whey products include various powders, whey protein concentrates and isolates, and fractionated proteins, such as a-lactalbumin and b-lactoglobulin. The increased interest in separation and fractionation of whey proteins arises from the differences in their functional, biological and nutritional properties. In response to concerns about environmental aspects, research has been focused on membrane filtration technology, which provides exciting new opportunities for large-scale protein and lactose fractionation. Membrane separation is such technique in which particles are separated according to their molecular size. The types of membrane processing techniques are ultrafiltration, microfiltration, reverse osmosis, pervaporation, electrodialysis and nanofiltration. A higher purification of whey proteins is possible by combining membrane separation with ion-exchange. This paper provides an overview of types and applications of membrane separation techniques

RADIATION STABILITY OF NAFION MEMBRANES USED FOR ISOTOPE SEPARATION BY PROTON EXCHANGE MEMBRANE ELECTROLYSIS

International Nuclear Information System (INIS)

Fox, E.

2009-01-01

Proton Exchange Membrane Electrolyzers have potential interest for use for hydrogen isotope separation from water. In order for PEME to be fully utilized, more information is needed on the stability of Nafion when exposed to radiation. This work examines Nafion 117 under varying exposure conditions, including dose rate, total dosage and atmospheric condition. Analytical tools, such as FT-IR, ion exchange capacity, DMA and TIC-TOC were used to characterize the exposed membranes. Analysis of the water from saturated membranes can provide important data on the stability of the membranes during radiation exposure. It was found that the dose rate of exposure plays an important role in membrane degradation. Potential mechanisms for membrane degradation include peroxide formation by free radicals

RADIATION STABILITY OF NAFION MEMBRANES USED FOR ISOTOPE SEPARATION BY PROTON EXCHANGE MEMBRANE ELECTROLYSIS

Energy Technology Data Exchange (ETDEWEB)

Fox, E

2009-05-15

Proton Exchange Membrane Electrolyzers have potential interest for use for hydrogen isotope separation from water. In order for PEME to be fully utilized, more information is needed on the stability of Nafion when exposed to radiation. This work examines Nafion 117 under varying exposure conditions, including dose rate, total dosage and atmospheric condition. Analytical tools, such as FT-IR, ion exchange capacity, DMA and TIC-TOC were used to characterize the exposed membranes. Analysis of the water from saturated membranes can provide important data on the stability of the membranes during radiation exposure. It was found that the dose rate of exposure plays an important role in membrane degradation. Potential mechanisms for membrane degradation include peroxide formation by free radicals.

Reliability demonstration methodology for products with Gamma Process by optimal accelerated degradation testing

International Nuclear Information System (INIS)

Zhang, Chunhua; Lu, Xiang; Tan, Yuanyuan; Wang, Yashun

2015-01-01

For products with high reliability and long lifetime, accelerated degradation testing (ADT) may be adopted during product development phase to verify whether its reliability satisfies the predetermined level within feasible test duration. The actual degradation from engineering is usually a strictly monotonic process, such as fatigue crack growth, wear, and erosion. However, the method for reliability demonstration by ADT with monotonic degradation process has not been investigated so far. This paper proposes a reliability demonstration methodology by ADT for this kind of product. We first apply Gamma process to describe the monotonic degradation. Next, we present a reliability demonstration method by converting the required reliability level into allowable cumulative degradation in ADT and comparing the actual accumulative degradation with the allowable level. Further, we suggest an analytical optimal ADT design method for more efficient reliability demonstration by minimizing the asymptotic variance of decision variable in reliability demonstration under the constraints of sample size, test duration, test cost, and predetermined decision risks. The method is validated and illustrated with example on reliability demonstration of alloy product, and is applied to demonstrate the wear reliability within long service duration of spherical plain bearing in the end. - Highlights: • We present a reliability demonstration method by ADT for products with monotonic degradation process, which may be applied to verify reliability with long service life for products with monotonic degradation process within feasible test duration. • We suggest an analytical optimal ADT design method for more efficient reliability demonstration, which differs from the existed optimal ADT design for more accurate reliability estimation by different objective function and different constraints. • The methods are applied to demonstrate the wear reliability within long service duration of

A continuous membrane microbioreactor system for development of integrated pectin modification and separation processes

DEFF Research Database (Denmark)

Zainal Alam, Muhd Nazrul Hisham Bin; Pinelo, Manuel; Samanta, Kama

2011-01-01

present a continuous membrane microbioreactor prototype for development of enzyme catalyzed degradation of pectin. Membrane reactors are becoming increasingly important for the novel ‘biorefining’ type of processes that either require product removal to avoid product inhibition or rest on partial...... hydrolysis of the substrate to obtain e.g. value-added oligosaccharides from complex biopolymers. The microbioreactor prototype was fabricated from poly(methylmethacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) and designed as a loop reactor (working volume approximately 190μL) integrated...... with a regenerated cellulose membrane for separation of low molecular weight products. The main technical considerations and challenges related to establishing the continuous membrane microbioreactor are discussed. The workability of the prototype was validated by comparing the process data at microscale to those...

Degradation products of irradiated haloperidol: implications for the development of an implantible delivery system

Energy Technology Data Exchange (ETDEWEB)

Booker, J

1988-01-01

Haloperidol was chosen as a model compound to determine whether the degradation products created by sterilizing dose of gamma radiation would contaminate an implantible delivery device and be hazardous to the health of the person using it. Acrolein, chlorobenzene, and several other products were identified among the degradation products. They were quantitated and evaluated as being potentially dangerous. It is recommended that the development protocol for a radiation-sterilized, implantible drug include the identification and evaluation of the degradation products.

Degradation products of irradiated haloperidol: implications for the development of an implantible delivery system

International Nuclear Information System (INIS)

Booker, J.

1988-01-01

Haloperidol was chosen as a model compound to determine whether the degradation products created by sterilizing dose of gamma radiation would contaminate an implantible delivery device and be hazardous to the health of the person using it. Acrolein, chlorobenzene, and several other products were identified among the degradation products. They were quantitated and evaluated as being potentially dangerous. It is recommended that the development protocol for a radiation-sterilized, implantible drug include the identification and evaluation of the degradation products. (author)

TBP degradation products. Separation and gas-chromatographic determination

International Nuclear Information System (INIS)

Kuada, T.A.; Alem, C.M.; Matsuda, H.T.; Araujo, B.F. de; Araujo, J.A de.

1991-11-01

A separation method for di butylphosphate, mono butylphosphate and phosphoric acid as degradation products in organic and aqueous streams of the process containing variable amounts of actinides and fission products is described. The products were separated by extraction and after methylation the final determination was carried out by gas chromatography. TPP was used as internal standard and 5 to 500 mg/L concentration range was determined with 1 to 10% deviation depending on the concentration of organo phosphates. (author)

Microbial degradation of coconut coir dust for biomass production

Energy Technology Data Exchange (ETDEWEB)

Uyenco, F.R.; Ochoa, J.A.K.

Several species of white-rot fungi were studied for its ability to degrade the lignocellulose components of coir dust at optimum conditions. The most effective fungi was Phanerochaeta chrysosporium UPCC 4003. This organism degraded the lignocellulose complex of coir dust at a rate of about 25 percent in 4 weeks. The degradation process was carried on with minimal nitrogen concentration, coconut water supplementation and moisture levels between 85-90 percent. Shake flask cultures of the degraded coir dust using cellulolytic fungi were not effective. In fermentor cultures with Chaetomium cellulolyticum UPCC 3934, supplemented coir dust was converted into a microbial biomass product (MBP) with 15.58 percent lignin, 19.20 percent cellulose and 18.87 percent protein. More work is being done on the utilization of coir dust on a low technology.

Assessment of proteolytic degradation of the basement membrane: a fragment of type IV collagen as a biochemical marker for liver fibrosis

DEFF Research Database (Denmark)

Veidal, Sanne S.; Karsdal, Morten A.; Nawrocki, Arkadiusz

2011-01-01

Collagen deposition and an altered matrix metalloproteinase (MMP) expression profile are hallmarks of fibrosis. Type IV collagen is the most abundant structural basement membrane component of tissue, which increases 14-fold during fibrogenesis in the liver. Proteolytic degradation of collagens...

Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water

Energy Technology Data Exchange (ETDEWEB)

Gui Minghui; Smuleac, Vasile [University of Kentucky, Department of Chemical and Materials Engineering (United States); Ormsbee, Lindell E. [University of Kentucky, Department of Civil Engineering (United States); Sedlak, David L. [University of California at Berkeley, Department of Civil and Environmental Engineering (United States); Bhattacharyya, Dibakar, E-mail: db@engr.uky.edu [University of Kentucky, Department of Chemical and Materials Engineering (United States)

2012-05-15

The potential for using hydroxyl radical (OH{sup Bullet }) reactions catalyzed by iron oxide nanoparticles (NPs) to remediate toxic organic compounds was investigated. Iron oxide NPs were synthesized by controlled oxidation of iron NPs prior to their use for contaminant oxidation (by H{sub 2}O{sub 2} addition) at near-neutral pH values. Cross-linked polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) microfiltration membranes were prepared by in situ polymerization of acrylic acid inside the membrane pores. Iron and iron oxide NPs (80-100 nm) were directly synthesized in the polymer matrix of PAA/PVDF membranes, which prevented the agglomeration of particles and controlled the particle size. The conversion of iron to iron oxide in aqueous solution with air oxidation was studied based on X-ray diffraction, Moessbauer spectroscopy and BET surface area test methods. Trichloroethylene (TCE) was selected as the model contaminant because of its environmental importance. Degradations of TCE and H{sub 2}O{sub 2} by NP surface generated OH{sup Bullet} were investigated. Depending on the ratio of iron and H{sub 2}O{sub 2}, TCE conversions as high as 100 % (with about 91 % dechlorination) were obtained. TCE dechlorination was also achieved in real groundwater samples with the reactive membranes.

Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water

International Nuclear Information System (INIS)

Gui Minghui; Smuleac, Vasile; Ormsbee, Lindell E.; Sedlak, David L.; Bhattacharyya, Dibakar

2012-01-01

The potential for using hydroxyl radical (OH • ) reactions catalyzed by iron oxide nanoparticles (NPs) to remediate toxic organic compounds was investigated. Iron oxide NPs were synthesized by controlled oxidation of iron NPs prior to their use for contaminant oxidation (by H 2 O 2 addition) at near-neutral pH values. Cross-linked polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) microfiltration membranes were prepared by in situ polymerization of acrylic acid inside the membrane pores. Iron and iron oxide NPs (80–100 nm) were directly synthesized in the polymer matrix of PAA/PVDF membranes, which prevented the agglomeration of particles and controlled the particle size. The conversion of iron to iron oxide in aqueous solution with air oxidation was studied based on X-ray diffraction, Mössbauer spectroscopy and BET surface area test methods. Trichloroethylene (TCE) was selected as the model contaminant because of its environmental importance. Degradations of TCE and H 2 O 2 by NP surface generated OH • were investigated. Depending on the ratio of iron and H 2 O 2 , TCE conversions as high as 100 % (with about 91 % dechlorination) were obtained. TCE dechlorination was also achieved in real groundwater samples with the reactive membranes.

Computational Modeling of Degradation of Substituted Benzyltrimethyl Ammonium: Preprint

Energy Technology Data Exchange (ETDEWEB)

Long, H.; Pivovar, B. S.

2014-09-01

The degradation of cations on the alkaline exchange membranes is the major challenge for alkaline membrane fuel cells. In this paper, we investigated the degradation barriers by density functional theory for substituted benzyltrimethyl ammonium (BTMA+) cations, which is one of the most commonly used cations for alkaline exchange membranes. We found that substituted cations with electron-releasing substituent groups at meta-position of the benzyl ring could result in improved degradation barriers. However, after investigating more than thirty substituted BTMA+ cations with ten different substituent groups, the largest improvement of degradation barriers is only 1.6 kcal/mol. This implies that the lifetime of alkaline membrane fuel cells could increase from a few months to a few years by using substituted BTMA+ cations, an encouraging but still limited improvement for real-world applications.

Degradation modeling and operational optimization for improving the lifetime of high-temperature PEM (proton exchange membrane) fuel cells

International Nuclear Information System (INIS)

Kim, Jintae; Kim, Minjin; Kang, Taegon; Sohn, Young-Jun; Song, Taewon; Choi, Kyoung Hwan

2014-01-01

High-temperature PEMFCs (proton exchange membrane fuel cells) using PA (phosphoric acid)-doped PBI (polybenzimidazole) membranes have received attention as a potential solution to several of the issues with traditional low-temperature PEMFCs. However, the durability of high-temperature PEMFCs deteriorates rapidly with increasing temperature, although its performance improves. This characteristic makes it difficult to select the proper operating temperature to achieve its target lifetime. In this paper, to resolve this problem, models were developed to predict the performance and durability of the high-temperature PEMFC as a function of operating temperature. The optimal operating temperature was then determined for a variety of lifetimes. Theoretical model to estimate cell performance and empirical model to predict the degradation rate of cell performance were constructed, respectively. The prediction results of the developed models agreed well with the experimental data. From the simulation, we could obtain higher average cell performances by optimizing the operating temperature for the given target lifetime compared to the cell performance at some temperatures determined using an existing rule of thumb. It is expected that the proposed methodologies will lead to the more rapid commercialization of this technology in such applications as stationary and automotive fuel cell systems. - Highlights: • High-temperature PEMFCs (proton exchange membrane fuel cells). • Operational optimization for improving the lifetime. • Development of the degradation modeling for high-temperature PEMFCs

Degradation product characterization of therapeutic oligonucleotides using liquid chromatography mass spectrometry.

Science.gov (United States)

Elzahar, N M; Magdy, N; El-Kosasy, Amira M; Bartlett, Michael G

2018-05-01

Synthetic antisense phosphorothioate oligonucleotides (PS) have undergone rapid development as novel therapeutic agents. The increasing significance of this class of drugs requires significant investment in the development of quality control methods. The determination of the many degradation pathways of such complex molecules presents a significant challenge. However, an understanding of the potential impurities that may arise is necessary to continue to advance these powerful new therapeutics. In this study, four different antisense oligonucleotides representing several generations of oligonucleotide therapeutic agents were evaluated under various stress conditions (pH, thermal, and oxidative stress) using ion-pairing reversed-phase liquid chromatography tandem mass spectrometry (IP-RPLC-MS/MS) to provide in-depth characterization and identification of the degradation products. The oligonucleotide samples were stressed under different pH values at 45 and 90 °C. The main degradation products were observed to be losses of nucleotide moieties from the 3'- and 5'-terminus, depurination, formation of terminal phosphorothioates, and production of ribose, ribophosphorothioates (Rp), and phosphoribophosphorothioates (pRp). Moreover, the effects of different concentrations of hydrogen peroxide were studied resulting in primarily extensive desulfurization and subsequent oxidation of the phosphorothioate linkage to produce the corresponding phosphodiester. The reaction kinetics for the degradation of the oligonucleotides under the different stress conditions were studied and were found to follow pseudo-first-order kinetics. Differences in rates exist even for oligonucleotides of similar length but consisting of different sequences. Graphical abstract Identification of degradation products across several generations of oligonucleotide therapeutics using LC-MS.

Durability of PEM Fuel Cell Membranes

Science.gov (United States)

Huang, Xinyu; Reifsnider, Ken

Durability is still a critical limiting factor for the commercialization of polymer electrolyte membrane (PEM) fuel cells, a leading energy conversion technology for powering future hydrogen fueled automobiles, backup power systems (e.g., for base transceiver station of cellular networks), portable electronic devices, etc. Ionic conducting polymer (ionomer) electrolyte membranes are the critical enabling materials for the PEM fuel cells. They are also widely used as the central functional elements in hydrogen generation (e.g., electrolyzers), membrane cell for chlor-alkali production, etc. A perfluorosulfonic acid (PFSA) polymer with the trade name Nafion® developed by DuPont™ is the most widely used PEM in chlor-alkali cells and PEM fuel cells. Similar PFSA membranes have been developed by Dow Chemical, Asahi Glass, and lately Solvay Solexis. Frequently, such membranes serve the dual function of reactant separation and selective ionic conduction between two otherwise separate compartments. For some applications, the compromise of the "separation" function via the degradation and mechanical failure of the electrolyte membrane can be the life-limiting factor; this is particularly the case for PEM in hydrogen/oxygen fuel cells.

Analysis of the Precursors, Simulants and Degradation Products of Chemical Warfare Agents.

Science.gov (United States)

Witkiewicz, Zygfryd; Neffe, Slawomir; Sliwka, Ewa; Quagliano, Javier

2018-09-03

Recent advances in analysis of precursors, simulants and degradation products of chemical warfare agents (CWA) are reviewed. Fast and reliable analysis of precursors, simulants and CWA degradation products is extremely important at a time, when more and more terrorist groups and radical non-state organizations use or plan to use chemical weapons to achieve their own psychological, political and military goals. The review covers the open source literature analysis after the time, when the chemical weapons convention had come into force (1997). The authors stated that during last 15 years increased number of laboratories are focused not only on trace analysis of CWA (mostly nerve and blister agents) in environmental and biological samples, but the growing number of research are devoted to instrumental analysis of precursors and degradation products of these substances. The identification of low-level concentration of CWA degradation products is often more important and difficult than the original CWA, because of lower level of concentration and a very large number of compounds present in environmental and biological samples. Many of them are hydrolysis products and are present in samples in the ionic form. For this reason, two or three instrumental methods are used to perform a reliable analysis of these substances.

Identification and in vitro cytotoxicity of ochratoxin A degradation products formed during coffee roasting.

Science.gov (United States)

Cramer, Benedikt; Königs, Maika; Humpf, Hans-Ulrich

2008-07-23

The mycotoxin ochratoxin A is degraded by up to 90% during coffee roasting. In order to investigate this degradation, model heating experiments with ochratoxin A were carried out, and the reaction products were analyzed by HPLC-DAD and HPLC-MS/MS. Two ochratoxin A degradation products were identified, and their structure and absolute configuration were determined. As degradation reactions, the isomerization to 14-(R)-ochratoxin A and the decarboxylation to 14-decarboxy-ochratoxin A were identified. Subsequently, an analytical method for the determination of these compounds in roasted coffee was developed. Quantification was carried out by HPLC-MS/MS and the use of stable isotope dilution analysis. By using this method for the analysis of 15 coffee samples from the German market, it could be shown that, during coffee roasting, the ochratoxin A diastereomer 14-(R)-ochratoxin A was formed in amounts of up to 25.6% relative to ochratoxin A. The decarboxylation product was formed only in traces. For toxicity evaluations, first preliminary cell culture assays were performed with the two new substances. Both degradation products exhibited higher IC50 values and caused apoptotic effects with higher concentrations than ochratoxin A in cultured human kidney epithelial cells. Thus, these cell culture data suggest that the degradation products are less cytotoxic than ochratoxin A.

Identification and ecotoxicity of degradation products of chloroacetamide herbicides from UV-treatment of water

DEFF Research Database (Denmark)

Souissi, Yasmine; Bouchonnet, Stéphane; Bourcier, Sophie

2013-01-01

The widespread occurrence of chlorinated herbicides and their degradation products in the aquatic environment raises health and environmental concerns. As a consequence pesticides, and to a lesser degree their degradation products, are monitored by authorities both in surface waters and drinking...... waters. In this study the formation of degradation products from ultraviolet (UV) treatment of the three chloroacetamide herbicides acetochlor, alachlor and metolachlor and their biological effects were investigated. UV treatment is mainly used for disinfection in water and wastewater treatments. First...

Modelling and sequential simulation of multi-tubular metallic membrane and techno-economics of a hydrogen production process employing thin-layer membrane reactor

KAUST Repository

Shafiee, Alireza

2016-09-24

A theoretical model for multi-tubular palladium-based membrane is proposed in this paper and validated against experimental data for two different sized membrane modules that operate at high temperatures. The model is used in a sequential simulation format to describe and analyse pure hydrogen and hydrogen binary mixture separations, and then extended to simulate an industrial scale membrane unit. This model is used as a sub-routine within an ASPEN Plus model to simulate a membrane reactor in a steam reforming hydrogen production plant. A techno-economic analysis is then conducted using the validated model for a plant producing 300 TPD of hydrogen. The plant utilises a thin (2.5 μm) defect-free and selective layer (Pd75Ag25 alloy) membrane reactor. The economic sensitivity analysis results show usefulness in finding the optimum operating condition that achieves minimum hydrogen production cost at break-even point. A hydrogen production cost of 1.98 $/kg is estimated while the cost of the thin-layer selective membrane is found to constitute 29% of total process capital cost. These results indicate the competiveness of this thin-layer membrane process against conventional methods of hydrogen production. © 2016 Hydrogen Energy Publications LLC

Degradation study of pesticides by direct photolysis - Structural characterization and potential toxicity of photo products

International Nuclear Information System (INIS)

Rifai, A.

2013-01-01

Pesticides belong to the large family of organic pollutants. In general, they are intended to fight against crop pests. Distribution of pesticides in nature creates pollution in DIFFERENT compartments of the biosphere (water, soil and air) and can induce acute toxic effects on human beings of the terrestrial and aquatic living biomass. It is now shown that some pesticides are endocrine disruptors and are particularly carcinogenic and mutagenic effects in humans. Pesticides can undergo various processes of transformation in the natural life cycle (biodegradation, volatilization, solar radiation ...) or following applied in the sectors of natural water purification and treatment stations sewage treatment. The presence of degradation products of pesticides in our environment is even more alarming that their structures and potential toxicities generally unknown. Molecules belonging to two families of pesticides were selected for this study: herbicides, represented by metolachlor, and fungicides represented by procymidone, pyrimethanil and boscalid. The first part of the thesis focused on the development of an analytical strategy to characterize the structures of compounds from degradation by photolysis of pesticides. The second part focused on estimating the toxicity of degradation products using a test database in silico. Identification of degradation products was achieved through two complementary analysis techniques: the gas chromatography coupled to a mass spectrometer ''multi-stage'' (GC-MSn) and liquid chromatography coupled to a tandem mass spectrometer (LC-MS/MS). The estimation of the toxicity of the degradation products was performed using the TEST program QSAR recently developed to try to predict the toxicity of molecules. The strategy of the structural elucidation of degradation products of pesticides studied is based on studying of the mechanisms of fragmentation of parent molecules of the degradation products. The molar mass of parent

Identification of major degradation products of 5-aminosalicylic acid formed in aqueous solutions and in pharmaceuticals

DEFF Research Database (Denmark)

Jensen, J.; Cornett, Claus; Olsen, C. E.

1992-01-01

of polymeric species by oxidative self-coupling of 5-ASA moieties. These results indicate that the degradation of 5-ASA follows the same mechanism as observed for the autooxidation of 4-aminophenol and 1,4-phenylenediamine. Some of the identified degradation products were found in 5-ASA......The formation of four major degradation products of 5-aminosalicylic acid (5-ASA) in buffered solutions at pH 7.0 was demonstrated by gradient HPLC analysis. The isolation and structural elucidation of the resulting degradation products showed that the degradation of 5-ASA led to the formation...

Identification of thermal degradation products of polymers by capillary gas chromatography

NARCIS (Netherlands)

Pacakova, V.; Borecka, M.; Leclercq, P.A.; Kaiser, R.E.

1981-01-01

Samples of polyethylene, polypropylene, polystyrene and five styrene copolymers were thermally degraded in a quartz tubular reactor at 5100e in an inert atmosphere. The degradation products were separated on-line on capillary coltmlS coated with squalane, OV-17 and SE-30 as stationary phases. The

Study on hydrophobicity degradation of gas diffusion layer in proton exchange membrane fuel cells

International Nuclear Information System (INIS)

Yu, Shuchun; Li, Xiaojin; Li, Jin; Liu, Sa; Lu, Wangting; Shao, Zhigang; Yi, Baolian

2013-01-01

Highlights: • The hydrophobicity degradation mechanism of GDL was proposed thoroughly. • C-O and C=O groups appeared on the surfaces of GDL after immersion. • The relative content of PTFE in GDL decreased after immersion. • The surfaces and inner structure of GDL destroyed after immersion. - Abstract: As one of the essential components of proton exchange membrane fuel cell (PEMFC), gas diffusion layer (GDL) is of importance on water management, as well on the performance and durability of PEMFC. In this paper, the hydrophobicity degradation of GDL was investigated by immersing it in the 1.0 mol L −1 H 2 SO 4 solution saturated by air for 1200 h. From the measurements of contact angle and water permeability, the hydrophobic characteristics of the pristine and immersed GDLs were compared. To investigate the causes for hydrophobicity degradation, the GDLs were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetry. Further, the chemical compositions of H 2 SO 4 solutions before and after immersion test were analyzed with infrared spectroscopy. Results showed that the hydrophobicity of immersed GDL decreased distinctly, which was caused by the damage of physical structure and surface characteristics. Moreover, the immersed GDL showed a worse fuel cell performance than the pristine GDL, especially under a low humidity condition

Identification of Forced Degradation Products of Itopride by LC-PDA and LC-MS.

Science.gov (United States)

Joshi, Payal; Bhoir, Suvarna; Bhagwat, A M; Vishwanath, K; Jadhav, R K

2011-05-01

Degradation products of itopride formed under different forced conditions have been identified using LC-PDA and LC-MS techniques. Itopride was subjected to forced degradation under the conditions of hydrolysis, photolysis, oxidation, dry and wet heat, in accordance with the International Conference on Harmonization. The stress solutions were chromatographed on reversed phase C18 (250×4.6 mm, 5 μm) column with a mobile phase methanol:water (55:45, v/v) at a detection wavelength of 215 nm. Itopride degraded in acid, alkali and oxidative stress conditions. The stability indicating method was developed and validated. The degradation pathway of the drug to products II-VIII is proposed.

Organochlorine Pesticides and Degradation Products in Soil around ...

African Journals Online (AJOL)

The levels and compositions of organochlorine pesticides and degradation products in soil samples collected from a former formulation plant in Morogoro municipality, Tanzania, were determined. Extraction was performed by pressurized fluid extraction using n-hexane:acetone (75:25) mixture. Clean-up of extracts was ...

Dependence of transformation product formation on pH during photolytic and photocatalytic degradation of ciprofloxacin

International Nuclear Information System (INIS)

Salma, Alaa; Thoröe-Boveleth, Sven; Schmidt, Torsten C.; Tuerk, Jochen

2016-01-01

Highlights: • Identification of transformation products using an isotopically labeled surrogate. • 4 of 18 detected transformation products have been identified for the first time. • Revision of 2 molecular structures of previously reported transformation products. • PH dependence of photolytic and photocatalytic degradation of ciprofloxacin. - Abstract: Ciprofloxacin (CIP) is a broad-spectrum antibiotic with five pH dependent species in aqueous medium, which makes its degradation behavior difficult to predict. For the identification of transformation products and prediction of degradation mechanisms, a new experimental concept making use of isotopically labeled compounds together with high resolution mass spectrometry was successfully established. The utilization of deuterated ciprofloxacin (CIP-d8) facilitated the prediction of three different degradation pathways and the corresponding degradation products, four of which were identified for the first time. Moreover, two molecular structures of previously reported transformation products were revised according to the mass spectra and product ion spectra of the deuterated transformation products. Altogether, 18 transformation products have been identified during the photolytic and photocatalytic reactions at different pH values (3, 5, 7 and 9). In this work the influence of pH on both reaction kinetics and degradation mechanism was investigated for direct ultraviolet photolysis (UV-C irradiation) and photocatalysis (TiO_2/UV-C). It could be shown that the removal rates strongly depended on pH with highest removal rates at pH 9. A comparison with those at pH 3 clearly indicated that under acidic conditions ciprofloxacin cannot be easily excited by UV irradiation. We could confirm that the first reaction step for both oxidative treatment processes is mainly defluorination, followed by degradation at the piperazine ring of CIP.

Dependence of transformation product formation on pH during photolytic and photocatalytic degradation of ciprofloxacin

Energy Technology Data Exchange (ETDEWEB)

Salma, Alaa [Institut für Energie- und Umwelttechnik e. V. (IUTA, Institute of Energy and Environmental Technology), Bliersheimer Straße 58-60, 47229 Duisburg (Germany); Thoröe-Boveleth, Sven [University Hospital Aachen, Institute for Hygiene and Environmental Medicine, Pauwelsstraße 30, 52074 Aachen (Germany); Schmidt, Torsten C. [University Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, 45141 Essen (Germany); Centre for Water and Environmental Research (ZWU), University Duisburg-Essen, Universitätsstraße 2, 45141 Essen (Germany); Tuerk, Jochen, E-mail: tuerk@iuta.de [Institut für Energie- und Umwelttechnik e. V. (IUTA, Institute of Energy and Environmental Technology), Bliersheimer Straße 58-60, 47229 Duisburg (Germany); Centre for Water and Environmental Research (ZWU), University Duisburg-Essen, Universitätsstraße 2, 45141 Essen (Germany)

2016-08-05

Highlights: • Identification of transformation products using an isotopically labeled surrogate. • 4 of 18 detected transformation products have been identified for the first time. • Revision of 2 molecular structures of previously reported transformation products. • PH dependence of photolytic and photocatalytic degradation of ciprofloxacin. - Abstract: Ciprofloxacin (CIP) is a broad-spectrum antibiotic with five pH dependent species in aqueous medium, which makes its degradation behavior difficult to predict. For the identification of transformation products and prediction of degradation mechanisms, a new experimental concept making use of isotopically labeled compounds together with high resolution mass spectrometry was successfully established. The utilization of deuterated ciprofloxacin (CIP-d8) facilitated the prediction of three different degradation pathways and the corresponding degradation products, four of which were identified for the first time. Moreover, two molecular structures of previously reported transformation products were revised according to the mass spectra and product ion spectra of the deuterated transformation products. Altogether, 18 transformation products have been identified during the photolytic and photocatalytic reactions at different pH values (3, 5, 7 and 9). In this work the influence of pH on both reaction kinetics and degradation mechanism was investigated for direct ultraviolet photolysis (UV-C irradiation) and photocatalysis (TiO{sub 2}/UV-C). It could be shown that the removal rates strongly depended on pH with highest removal rates at pH 9. A comparison with those at pH 3 clearly indicated that under acidic conditions ciprofloxacin cannot be easily excited by UV irradiation. We could confirm that the first reaction step for both oxidative treatment processes is mainly defluorination, followed by degradation at the piperazine ring of CIP.

A new-generation asymmetric multi-bore hollow fiber membrane for sustainable water production via vacuum membrane distillation.

Science.gov (United States)

Wang, Peng; Chung, Tai-Shung

2013-06-18

Due to the growing demand for potable water, the capacities for wastewater reclamation and saline water desalination have been increasing. More concerns are raised on the poor efficiency of removing certain contaminants by the current water purification technologies. Recent studies demonstrated superior separation performance of the vacuum membrane distillation (VMD) technology for the rejection of trace contaminants such as boron, dye, endocrine-disruptive chemical, and chloro-compound. However, the absence of suitable membranes with excellent wetting resistance and high permeation flux has severely hindered the VMD application as an effective water production process. This work presents a new generation multibore hollow fiber (MBF) membrane with excellent mechanical durability developed for VMD. Its micromorphology was uniquely designed with a tight surface and a fully porous matrix to maximize both high wetting resistance and permeation flux. Credit to the multibore configuration, a 65% improvement was obtained on the antiwetting property. Using a synthetic seawater feed, the new membrane with optimized fabrication condition exhibits a high flux and the salt rejection is consistently greater than 99.99%. In addition, a comparison of 7-bore and 6-bore MBF membranes was performed to investigate the optimum geometry design. The newly designed MBF membrane not only demonstrates its suitability for VMD but also makes VMD come true as an efficient process for water production.

Permeability testing of biomaterial membranes

Energy Technology Data Exchange (ETDEWEB)

Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B [NMI Natural and Medical Sciences Institute at University Tuebingen, Markwiesenstr. 55, D-72770 Reutlingen (Germany); Ahlers, M [GELITA AG, Gammelsbacher Str. 2, D-69412 Eberbach (Germany)], E-mail: schlosshauer@nmi.de

2008-09-01

The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation.

Permeability testing of biomaterial membranes

International Nuclear Information System (INIS)

Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B; Ahlers, M

2008-01-01

The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation

Degradation of graphene coated copper in simulated proton exchange membrane fuel cell environment: Electrochemical impedance spectroscopy study

Science.gov (United States)

Ren, Y. J.; Anisur, M. R.; Qiu, W.; He, J. J.; Al-Saadi, S.; Singh Raman, R. K.

2017-09-01

Metallic materials are most suitable for bipolar plates of proton exchange membrane fuel cell (PEMFC) because they possess the required mechanical strength, durability, gas impermeability, acceptable cost and are suitable for mass production. However, metallic bipolar plates are prone to corrosion or they can passivate under PEMFC environment and interrupt the fuel cell operation. Therefore, it is highly attractive to develop corrosion resistance coating that is also highly conductive. Graphene fits these criteria. Graphene coating is developed on copper by chemical vapor deposition (CVD) with an aim to improving corrosion resistance of copper under PEMFC condition. The Raman Spectroscopy shows the graphene coating to be multilayered. The electrochemical degradation of graphene coated copper is investigated by electrochemical impedance spectroscopy (EIS) in 0.5 M H2SO4 solution at room temperature. After exposure to the electrolyte for up to 720 h, the charge transfer resistance (Rt) of the graphene coated copper is ∼3 times greater than that of the bare copper, indicating graphene coatings could improve the corrosion resistance of copper bipolar plates.

Relationship between gas production and starch degradation in feed samples

NARCIS (Netherlands)

Chai, W.Z.; Gelder, van A.H.; Cone, J.W.

2004-01-01

An investigation was completed of the possibilities to estimate starch fermentation in rumen fluid using the gas production technique by incubating the total sample. Gas production from six starchy feed ingredients and eight maize silage samples were recorded and related to starch degradation

Rapid establishment of phenol- and quinoline-degrading consortia driven by the scoured cake layer in an anaerobic baffled ceramic membrane bioreactor.

Science.gov (United States)

Wang, Wei; Wang, Shun; Ren, Xuesong; Hu, Zhenhu; Yuan, Shoujun

2017-11-01

Although toxic and refractory organics, such as phenol and quinoline, are decomposed by anaerobic bacteria, the establishment of specific degrading consortia is a relatively slow process. An anaerobic membrane bioreactor allows for complete biomass retention that can aid the establishment of phenol- and quinoline-degrading consortia. In this study, the anaerobic digestion of phenol (500 mg L -1 ) and quinoline (50 mg L -1 ) was investigated using an anaerobic baffled ceramic membrane bioreactor (ABCMBR). The results showed that, within 30 days, 99% of phenol, 98% of quinoline and 88% of chemical oxygen demand (COD) were removed. The substrate utilisation rates of the cake layer for phenol and quinoline, and specific methanogenic activity of the cake layer, were 7.58 mg phenol g -1  mixed liquor volatile suspended solids (MLVSS) day -1 , 8.23 mg quinoline g -1  MLVSS day -1 and 0.55 g COD CH4  g -1  MLVSS day -1 , respectively. The contribution of the cake layer to the removals of phenol and quinoline was extremely underestimated because the uncounted scoured cake layer was disregarded. Syntrophus was the key population for phenol and quinoline degradation, and it was more abundant in the cake layer than in the bulk sludge. The highly active scattered cake layer sped up the establishment of phenol- and quinoline-degrading consortia in the ABCMBR.

Conversion of waste polystyrene through catalytic degradation into valuable products

Energy Technology Data Exchange (ETDEWEB)

Shah, Jasmin; Jan, Muhammad Rasul; Adnan [University of Peshawar, Peshawar (Pakistan)

2014-08-15

Waste expanded polystyrene (EPS) represents a source of valuable chemical products like styrene and other aromatics. The catalytic degradation was carried out in a batch reactor with a mixture of polystyrene (PS) and catalyst at 450 .deg. C for 30 min in case of Mg and at 400 .deg. C for 2 h both for MgO and MgCO{sub 3} catalysts. At optimum degradation conditions, EPS was degraded into 82.20±3.80 wt%, 91.60±0.20 wt% and 81.80±0.53 wt% liquid with Mg, MgO and MgCO{sub 3} catalysts, respectively. The liquid products obtained were separated into different fractions by fractional distillation. The liquid fractions obtained with three catalysts were compared, and characterized using GC-MS. Maximum conversion of EPS into styrene monomer (66.6 wt%) was achieved with Mg catalyst, and an increase in selectivity of compounds was also observed. The major fraction at 145 .deg. C showed the properties of styrene monomer. The results showed that among the catalysts used, Mg was found to be the most effective catalyst for selective conversion into styrene monomer as value added product.

Optimization of a membrane reactor for hydrogen production with genetic algorithms

International Nuclear Information System (INIS)

Raceanu, Mircea; Iordache, Ioan; Curuia, Marian; Rasoi, Gabriel; Patularu, Laurentiu; Enache, Adrian

2009-01-01

Full text: Hydrogen is produced via steam reforming of hydrocarbons such as natural gas or methane by using conventional systems. Unfortunately, these systems need at least four different stages, consisting of three reactors and a purification system. Moreover, the steam reforming reaction is an endothermic thermodynamically limited system, meaning that high temperature energy supply is needed for complete conversion. Among different technologies related to production, separation and purification of H 2 , membrane technologies seem to really play a fundamental role. The specific thermodynamic limits are overcome using the so-called membrane reactors, systems in which both reaction and separation occur simultaneously. The hydrogen is driven across the membrane by the pressure difference, depending on the temperature, pressure and reactor length the methane can be completely converted and consequently very pure hydrogen is produced. A membrane reactor has two components which can be optimized namely, the membrane and the reactor dimensions. This paper presents a study on optimization of membrane reactor for enhancing the overall production. A mathematical heterogeneous model of the reactor was used for optimization of reactor performance. Genetic algorithms were used as powerful methods for optimization of complex problems. (authors)

An integrated membrane system for the biocatalytic production of 3′-sialyllactose from dairy by-products

DEFF Research Database (Denmark)

Luo, Jianquan; Nordvang, Rune Thorbjørn; Morthensen, Sofie Thage

2014-01-01

An integrated membrane system was investigated for the production of 30-sialyllactose by an engineered sialidase using casein glycomacropeptide (CGMP) and lactose as substrates. CGMP was purified by ultrafiltration (UF) to remove any small molecules present and then an enzymatic membrane reactor ...

Analysis of deltamethrin's degradation products by irradiation

International Nuclear Information System (INIS)

Wu Ling; Huang Min; Chen Chun; Lei Qing; Du Xiaoying; Xie Yan; Wang Yan; Gao Peng; He Jiang

2012-01-01

Deltamethrin were dissolved in ethanol and water; acetone and water; dimethylsulfoxide and water, irradiating these liquors by 60 Co-γ under the dose of 5∼50 kGy. The irradiation system were analyzed by GC/MS, result shows: there were some differences under different irradiation doses; the main degradation products are: α-cyano-3-phenoxy benzyl alcohol, 3-Phenoxybenzaldehyde, 3-Phenoxybenzacetonitrile and bromomethane. (authors)

Palladium based membranes and membrane reactors for hydrogen production and purification : An overview of research activities at Tecnalia and TU/e

NARCIS (Netherlands)

Fernandez, E.; Helmi Siasi Farimani, A.; Medrano Jimenez, J.A.; Coenen, K.T.; Arratibel Plazaola, A.; Melendez Rey, J.; de Nooijer, N.C.A.; Viviente, J.L.; Zuniga, J.; van Sint Annaland, M.; Gallucci, F.; Pacheco Tanaka, D.A.

2017-01-01

In this paper, the main achievements of several European research projects on Pd based membranes and Pd membrane reactors for hydrogen production are reported. Pd-based membranes have received an increasing interest for separation and purification of hydrogen. In addition, the integration of such

Inorganic membranes for hydrogen production and purification: a critical review and perspective.

Science.gov (United States)

Lu, G Q; Diniz da Costa, J C; Duke, M; Giessler, S; Socolow, R; Williams, R H; Kreutz, T

2007-10-15

Hydrogen as a high-quality and clean energy carrier has attracted renewed and ever-increasing attention around the world in recent years, mainly due to developments in fuel cells and environmental pressures including climate change issues. In thermochemical processes for hydrogen production from fossil fuels, separation and purification is a critical technology. Where water-gas shift reaction is involved for converting the carbon monoxide to hydrogen, membrane reactors show great promises for shifting the equilibrium. Membranes are also important to the subsequent purification of hydrogen. For hydrogen production and purification, there are generally two classes of membranes both being inorganic: dense phase metal and metal alloys, and porous ceramic membranes. Porous ceramic membranes are normally prepared by sol-gel or hydrothermal methods, and have high stability and durability in high temperature, harsh impurity and hydrothermal environments. In particular, microporous membranes show promises in water gas shift reaction at higher temperatures. In this article, we review the recent advances in both dense phase metal and porous ceramic membranes, and compare their separation properties and performance in membrane reactor systems. The preparation, characterization and permeation of the various membranes will be presented and discussed. We also aim to examine the critical issues in these membranes with respect to the technical and economical advantages and disadvantages. Discussions will also be made on the relevance and importance of membrane technology to the new generation of zero-emission power technologies.

Treatment of low level radioactive liquid waste containing appreciable concentration of TBP degraded products.

Science.gov (United States)

Valsala, T P; Sonavane, M S; Kore, S G; Sonar, N L; De, Vaishali; Raghavendra, Y; Chattopadyaya, S; Dani, U; Kulkarni, Y; Changrani, R D

2011-11-30

The acidic and alkaline low level radioactive liquid waste (LLW) generated during the concentration of high level radioactive liquid waste (HLW) prior to vitrification and ion exchange treatment of intermediate level radioactive liquid waste (ILW), respectively are decontaminated by chemical co-precipitation before discharge to the environment. LLW stream generated from the ion exchange treatment of ILW contained high concentrations of carbonates, tributyl phosphate (TBP) degraded products and problematic radio nuclides like (106)Ru and (99)Tc. Presence of TBP degraded products was interfering with the co-precipitation process. In view of this a modified chemical treatment scheme was formulated for the treatment of this waste stream. By mixing the acidic LLW and alkaline LLW, the carbonates in the alkaline LLW were destroyed and the TBP degraded products got separated as a layer at the top of the vessel. By making use of the modified co-precipitation process the effluent stream (1-2 μCi/L) became dischargeable to the environment after appropriate dilution. Based on the lab scale studies about 250 m(3) of LLW was treated in the plant. The higher activity of the TBP degraded products separated was due to short lived (90)Y isotope. The cement waste product prepared using the TBP degraded product was having good chemical durability and compressive strength. Copyright © 2011 Elsevier B.V. All rights reserved.

Phosphorus, carbon- and nitrogen interactions in productive and degraded tropical pastures

Science.gov (United States)

Oberson, A.; Hegglin, D. D.; Nesper, M.; Rao, I.; Fonte, S.; Ramirez, B.; Velasquez, J.; Tamburini, F.; Bünemann, E. K.; Frossard, E.

2011-12-01

Pastures are the main land use in deforested areas of tropical South America. The highly weathered soils of these regions usually have low total and available phosphorus (P) contents. Low P availability can strongly limit plant and animal productivity and other soil ecosystem functions. Most introduced pastures of Brachiaria spp. are grass-alone (GA) while some are grass-legume (GL) pastures. The majority of the introduced pastures, particularly the grass-alone are at some state of degradation (GD). Pasture degradation induces severe loss of plant biomass production, with drastic ecological and economic implications. Although the importance of P deficiency in pasture degradation has been recognized, the knowledge generated on stoichiometry of carbon (C), nitrogen (N) and P along pathways of the nutrient cycles of pastures, with different botanical composition and productivity, has been very limited. We will present results of a case study realized during 2010 to 2011 in the forest margins agro-ecosystem of the department of Caquetá, Colombia. Our objectives were to determine: i) whether P availability is lower in degraded compared to productive pastures, and ii) whether the introduction of legumes in the pasture increases P availability through enhanced biological P cycling through plant growth, plant litter decomposition and the soil microbial biomass; and iii) whether pasture types (GA vs GL) and the state of pasture degradation affect the C:N:P ratios in nutrient pools of the soil-plant system. An on-farm study was conducted on nine farms in the department of Caquetá, Colombia. On every farm three different pasture types were studied: degraded grass alone pastures (GD), productive grass-alone pastures (GA) and productive grass-legume pastures (GL). Basic soil characteristics and indicators on soil P status, microbial P cycling, plant biomass production, plant litter deposition and nutrient concentrations in plant tissue were determined. Analysis of P, C and N

High performance liquid chromatographic analysis of insulin degradation products from a cultured kidney cell line

International Nuclear Information System (INIS)

Duckworth, W.C.; Hamel, F.G.; Liepnieks, J.; Frank, B.H.; Yagil, C.; Rabkin, R.

1988-01-01

The kidney is a major site for insulin removal and degradation, but the subcellular processes and enzymes involved have not been established. We have examined this process by analyzing insulin degradation products by HPLC. Monoiodoinsulin specifically labeled on either the A14 or B26 tyrosine residue was incubated with a cultured kidney epithelial cell line, and both intracellular and extracellular products were examined on HPLC. The products were then compared with products of known structure generated by hepatocytes and the enzyme insulin protease. Intracellular and extracellular products were different, suggesting two different degradative pathways, as previously shown in liver. The extracellular degradation products eluted from HPLC both before and after sulfitolysis similarly with hepatocyte products and products generated by insulin protease. The intracellular products also eluted identically with hepatocyte products. Based on comparisons with identified products, the kidney cell generates two fragments from the A chain of intact insulin, one with a cleavage at A13-A14 and the other at A14-A15. The B chain of intact insulin is cleaved in a number of different sites, resulting in peptides that elute identically with B chain peptides cleaved at B9-B10, B13-B14, B16-B17, B24-B25, and B25-B26. These similarities with hepatocytes and insulin protease suggest that liver and kidney have similar mechanisms for insulin degradation and that insulin protease or a very similar enzyme is involved in both tissues

A Miniature Membrane Reactor for Evaluation of Process Design Options on the Enzymatic Degradation of Pectin

DEFF Research Database (Denmark)

Zainal Alam, Muhd Nazrul Hisham; Pinelo, Manuel; Arnous, Anis

2011-01-01

was fabricated from poly(methylmethacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) with a working volume of ∼190 μL. The prototype also contained the necessary sensors and actuators, i.e., pressure transducer, mixing via magnetic stirrer bar and a temperature controller. The functionality of the prototype...... was demonstrated by performing a continuous enzymatic degradation of pectin experiment for a range of reactor conditions: different membrane molecular weight cutoff (MWCO) values, enzyme-to-substrate ratios (E/S), and substrate feeding rates (F) were assessed. Based on the experimental data, it was found...

Quantifying Contribution of Synthrophic Acetate Oxidation to Methane Production in Thermophilic Anaerobic Reactors by Membrane Inlet Mass Spectrometry

DEFF Research Database (Denmark)

Mulat, Daniel Girma; Ward, Alastair James; Adamsen, Anders Peter S.

2014-01-01

A unique method was developed and applied for monitoring methanogenesis pathways based on isotope labeled substrates combined with online membrane inlet quadrupole mass spectrometry (MIMS). In our study, a fermentation sample from a full-scale biogas plant fed with pig and cattle manure, maize...... silage, and deep litter was incubated with 100 mM of [2-13C] sodium acetate under thermophilic anaerobic conditions. MIMS was used to measure the isotopic distribution of dissolved CO2 and CH4 during the degradation of acetate, while excluding interference from water by applying a cold trap. After 6 days...... a new approach for online quantification of the relative contribution of methanogenesis pathways to methane production with a time resolution shorter than one minute. The observed contribution of SAO-HM to methane production under the tested conditions challenges the current widely accepted anaerobic...

Production of Biodiesel Using a Membrane Reactor to Minimize Separation Cost

Science.gov (United States)

Olagunju, O. A.; Musonge, P.

2017-07-01

This study investigates the performance of a packed bed membrane reactor in the transesterification process of triglycerides to methyl ester using soyabean oil as feedstock. A TiO2/Al2O3 ceramic microporous membrane was selected due to its chemical inert nature and thermal stability to selectively remove the product from the reaction medium. CaO impregnated on the surface of activated carbon was packed into the membrane and acted as catalyst. The synthesized catalyst had a total loading of 40.50 % and was characterized by XRD and temperature-programmed desorption of CO2 (CO2-TPD). The crude biodiesel produced was micro-filtered by the ceramic membrane with a pore size of 0.02 μm to retain the unreacted oil and free glycerol, at the transmembrane pressure of 100 KPa. The best condition was achieved with a temperature of 65 °C, methanol/oil molar ratio of 6:1 for 150 minutes, which resulted in the highest FAME yield of 94 %. Methyl ester produced met the ASTM D6751 and SANS 1935 specifications. The product obtained was mainly composed of methyl esters. Glycerol was not detected in the product stream due to the ability of the membrane to retain the glycerol and the unreacted oil in the medium, which solved the issue of glycerol separation from biodiesel.

Suppression of type I interferon production by porcine epidemic diarrhea virus and degradation of CREB-binding protein by nsp1

Energy Technology Data Exchange (ETDEWEB)

Zhang, Qingzhan; Shi, Kaichuang; Yoo, Dongwan, E-mail: dyoo@illinois.edu

2016-02-15

Type I interferons (IFN-α/β) are the major components of the innate immune response of hosts, and in turn many viruses have evolved to modulate the host response during infection. We found that the IFN-β production was significantly suppressed during PEDV infection in cells. To identify viral IFN antagonists and to study their suppressive function, viral coding sequences for the entire structural and nonstructural proteins were cloned and expressed. Of 16 PEDV nonstructural proteins (nsps), nsp1, nsp3, nsp7, nsp14, nsp15 and nsp16 were found to inhibit the IFN-β and IRF3 promoter activities. The sole accessory protein ORF3, structure protein envelope (E), membrane (M), and nucleocapsid (N) protein were also shown to inhibit such activities. PEDV nsp1 did not interfere the IRF3 phosphorylation and nuclear translocation but interrupted the enhanceosome assembly of IRF3 and CREB-binding protein (CBP) by degrading CBP. A further study showed that the CBP degradation by nsp1 was proteasome-dependent. Our data demonstrate that PEDV modulates the host innate immune responses by degrading CBP and suppressing ISGs expression. - Highlights: • PEDV modulates the host innate immune system by suppressing the type I interferon production and ISGs expression. • Ten viral proteins were identified as IFN antagonists, and nsp1 was the most potent viral IFN antagonist. • PEDV nsp1 did not interfere the IRF3 phosphorylation and nuclear translocation but interrupted the enhanceosome assembly of IRF3 and CREB-binding protein (CBP). • PEDV nsp1 caused the CBP degradation in the nucleus, which may be the key mechanism for PEDV-mediated IFN downregulation.

Particulate and gas-phase products from the atmospheric degradation of chlorpyrifos and chlorpyrifos-oxon

Science.gov (United States)

Borrás, Esther; Ródenas, Milagros; Vázquez, Mónica; Vera, Teresa; Muñoz, Amalia

2015-12-01

The phosphorothioate structure is highly present in several pesticides. However, there is a lack of information about its degradation process in air and the secondary pollutants formed. Herein, the atmospheric reactions of chlorpyrifos, one of the most world-used insecticide, and its main degradation product - chlorpyrifos-oxon - are described. The photo-oxidation under the presence of NOx was studied in a large outdoor simulation chamber for both chlorpyrifos and chlorpyrifos-oxon, observing a rapid degradation (Half lifetime < 3.5 h for both compounds). Also, the photolysis reactions of both were studied. The formation of particulate matter (aerosol mass yield ranged 6-59%) and gaseous products were monitored. The chemical composition of minor products was studied, identifying 15 multi-oxygenated derivatives. The most abundant products were ring-retaining molecules such as 3,5,6-trichloropyridin-2-ol and ethyl 3,5,6-trichloropyridin-2-yl hydrogen phosphate. An atmospheric degradation mechanism has been amplified based on an oxidation started with OH-nucleophilic attack to Pdbnd S bond.

Investigation of degradation products of cocaine and benzoylecgonine in the aquatic environment

International Nuclear Information System (INIS)

Bijlsma, Lubertus; Boix, Clara; Niessen, Wilfried M.A.; Ibáñez, María; Sancho, Juan V.; Hernández, Félix

2013-01-01

In this work, ultra-high-performance liquid chromatography (UHPLC) coupled to a hybrid quadrupole time-of-flight mass spectrometer (QTOF MS) has allowed the discovery and elucidation of degradation products of cocaine and its main metabolite benzoylecgonine (BE) in water. Spiked surface water was subjected to hydrolysis, chlorination and photo-degradation (both ultraviolet irradiation and simulated sunlight). After degradation of cocaine, up to sixteen compounds were detected and tentatively identified (1 resulting from hydrolysis; 8 from chlorination; 7 from photo-degradation), three of which are well known cocaine metabolites (BE, norbenzoylecgonine and norcocaine). Regarding BE degradation, up to ten compounds were found (3 from chlorination; 7 from photo-degradation), including one known metabolite (norbenzoylecgonine). Since reference standards were available for the major metabolites, they could be confirmed using information on retention time and fragment ions. The other degradates resulted from chlorination, dealkylation, hydroxylation and nitration, or from a combination of these processes. Several influent and effluent sewage water, and surface water samples were then screened for the identified compounds (known and unknown) using UHPLC–tandem MS with triple quadrupole. BE, norcocaine and norbenzoylecgonine were identified in these samples as major metabolites. Four previously unreported degradates were also found in some of the samples under study, illustrating the usefulness and applicability of the degradation experiments performed in this work. Highlights: ► Cocaine and benzoylecgonine degradation/transformation products investigated in water ► Hydrolysis, chlorination and photo degradation studied under laboratory conditions ► Several TPs discovered and tentatively elucidated by high resolution MS ► Structures of non-previously reported TPs have been suggested. ► Several reported/known TPs but also new TPs were found in sewage and surface

Investigation of degradation products of cocaine and benzoylecgonine in the aquatic environment

Energy Technology Data Exchange (ETDEWEB)

Bijlsma, Lubertus; Boix, Clara [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellón (Spain); Niessen, Wilfried M.A. [hyphen MassSpec, Leiden (Netherlands); Ibáñez, María; Sancho, Juan V. [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellón (Spain); Hernández, Félix, E-mail: felix.hernandez@uji.es [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellón (Spain)

2013-01-15

In this work, ultra-high-performance liquid chromatography (UHPLC) coupled to a hybrid quadrupole time-of-flight mass spectrometer (QTOF MS) has allowed the discovery and elucidation of degradation products of cocaine and its main metabolite benzoylecgonine (BE) in water. Spiked surface water was subjected to hydrolysis, chlorination and photo-degradation (both ultraviolet irradiation and simulated sunlight). After degradation of cocaine, up to sixteen compounds were detected and tentatively identified (1 resulting from hydrolysis; 8 from chlorination; 7 from photo-degradation), three of which are well known cocaine metabolites (BE, norbenzoylecgonine and norcocaine). Regarding BE degradation, up to ten compounds were found (3 from chlorination; 7 from photo-degradation), including one known metabolite (norbenzoylecgonine). Since reference standards were available for the major metabolites, they could be confirmed using information on retention time and fragment ions. The other degradates resulted from chlorination, dealkylation, hydroxylation and nitration, or from a combination of these processes. Several influent and effluent sewage water, and surface water samples were then screened for the identified compounds (known and unknown) using UHPLC–tandem MS with triple quadrupole. BE, norcocaine and norbenzoylecgonine were identified in these samples as major metabolites. Four previously unreported degradates were also found in some of the samples under study, illustrating the usefulness and applicability of the degradation experiments performed in this work. Highlights: ► Cocaine and benzoylecgonine degradation/transformation products investigated in water ► Hydrolysis, chlorination and photo degradation studied under laboratory conditions ► Several TPs discovered and tentatively elucidated by high resolution MS ► Structures of non-previously reported TPs have been suggested. ► Several reported/known TPs but also new TPs were found in sewage and surface

Chemical and photochemical degradation of chlorantraniliprole and characterization of its transformation products.

Science.gov (United States)

Lavtižar, Vesna; van Gestel, Cornelis A M; Dolenc, Darko; Trebše, Polonca

2014-01-01

This study aimed at assessing the photodegradation of the insecticide chlorantraniliprole (CAP) in deionized water and in tap water amended with humic acids and nitrate. Photolysis was carried out under simulated solar or UV-A light. CAP (39 μM) photodegradation was slightly faster in tap water than in deionized water with half lives of 4.1 and 5.1 days, respectively. Photodegradation rate of CAP was hardly affected by humic acids (up to 100 mg L(-1)) and nitrate. Photodegradation pattern was different in slightly acidic (pH=6.1) deionized water compared to basic (pH=8.0) tap water. Four main degradation products have been isolated and characterized spectroscopically, and crystal structure was recorded for the first two photodegradation products. CAP also degraded in the dark controls, but only at basic pH (23% loss at pH 8.0 in tap water after 6 days), resulting in the formation of one single degradation product. Our study shows that the degradation of chlorantraniliprole in water is a combination of chemical and photochemical reactions, which are highly dependent on the pH of the solution. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dilaton dynamics from production of tensionless membranes

International Nuclear Information System (INIS)

Cremonini, Sera; Watson, Scott

2006-01-01

In this paper we consider classical and quantum corrections to cosmological solutions of 11D supergravity (SUGRA) coming from dynamics of membrane states. We first consider the supermembrane spectrum following the approach of Russo and Tseytlin for consistent quantization. We calculate the production rate of Bogomol'nyi-Prasad-Sommerfield (BPS) membrane bound states in a cosmological background and find that such effects are generically suppressed by the Planck scale, as expected. However, for a modified brane spectrum possessing enhanced symmetry, production can be finite and significant. We stress that this effect could not be anticipated given only a knowledge of the low-energy effective theory. Once on shell, inclusion of these states leads to an attractive force pulling the dilaton towards a fixed point of S-duality, namely g s =1. Although the SUGRA description breaks down in this regime, inclusion of the enhanced states suggests that the center of M-theory moduli space is a dynamical attractor. Moreover, our results seem to suggest that string dynamics does indeed favor a vacuum near fixed points of duality

LC/MS/MS identification of some folic acid degradation products after E-beam irradiation

International Nuclear Information System (INIS)

Araújo, M.M.; Marchioni, E.; Zhao, M.; Kuntz, F.; Di Pascoli, T.; Villavicencio, A.L.C.H.; Bergaentzle, M.

2012-01-01

Folates belong to the B vitamin group based on the parental compound folic acid (FA). They are involved in important biochemical processes like DNA synthesis and repair. FA is composed of a pteridine ring, p-aminobenzoic acid and glutamate moieties. The human metabolism is not able to synthesize folates and therefore obtain them from diet. FA, a synthetic vitamin, is used as a food fortificant because of its low price, relative stability and increased bioavailability compared to natural folate forms. FA is known to be a sensitive compound easily degradable in aqueous solution by ultraviolet and visible light towards various by-products. Irradiation is a process for preservation of foods that uses accelerated electrons, gamma rays or X-rays. Irradiation is proposed for the treatment of various food products, eliminating or reducing pathogens and insects, increasing the storage time and replacing chemical fumigants. This study concerns the identification of degradation products of FA after E-beam irradiation. FA aqueous solutions were irradiated with a Van de Graaff electrons beam accelerator (2 MeV, 100 μA current, 20 cm scan width, dose rate about 2 kGy/s). Applied doses were between 0 (control) and 10.0 kGy. Absorbed doses were monitored with FWT 60.00 radiochromic dosimeters. - Highlights: ► We investigated the degradation of folic acid aqueous solution after electron beam treatment. ► Radiation doses over 5 kGy promote huge folic acid degradation and appearance of several degradation products. ► PCA, PABA and pABGA, already known folic acid degradation products, are formed due to E-beam treatment. ► Xanthopterin, a new radio-induced breakdown product, is formed after irradiation treatment.

Isolation and characterization of the E. coli membrane protein production strain Mutant56(DE3)

DEFF Research Database (Denmark)

Baumgarten, Thomas; Schlegel, Susan; Wagner, Samuel

2017-01-01

Membrane protein production is usually toxic to E. coli. However, using genetic screens strains can be isolated in which the toxicity of membrane protein production is reduced, thereby improving production yields. Best known examples are the C41(DE3) and C43(DE3) strains, which are both derived...... from the T7 RNA polymerase (P)-based BL21(DE3) protein production strain. In C41(DE3) and C43(DE3) mutations lowering t7rnap expression levels result in strongly reduced T7 RNAP accumulation levels. As a consequence membrane protein production stress is alleviated in the C41(DE3) and C43(DE3) strains......, thereby increasing membrane protein yields. Here, we isolated Mutant56(DE3) from BL21(DE3) using a genetic screen designed to isolate BL21(DE3)-derived strains with mutations alleviating membrane protein production stress other than the ones in C41(DE3) and C43(DE3). The defining mutation of Mutant56(DE3...

Membrane reforming in converting natural gas to hydrogen: Production costs, Part II

Energy Technology Data Exchange (ETDEWEB)

Iaquaniello, G; Cosenza, S [Technip-KTI S.p.A., via Castello della Magliana 75, Rome (Italy); Giacobbe, F; Morico, B; Farace, A [Processi Innovativi s.r.l., L' Aquila (Italy)

2008-11-15

This paper evaluates the production costs of a hybrid system based on a new membrane reforming MRR concept to convert natural gas to hydrogen and electricity. Membrane reforming with hydrogen-selective, palladium-silver membranes pushes the chemical equilibrium and allows higher methane conversions at lower temperature such as 650 C. The new MRR concept formed of a series of modules is put forward herein. Each module is made up of a reforming step and an external membrane separation unit. The estimates, based on utilities costs of a typical Italian refinery (end of 2006), show that the production costs for the hybrid system are 30% less than conventional tubular steam reforming technology, and 13% less than a gas-fired cogeneration plant coupled with a conventional H{sub 2} plant. (author)

Characteristics and fates of soluble microbial products in ceramic membrane bioreactor at various sludge retention times.

Science.gov (United States)

Shin, Hang-Sik; Kang, Seok-Tae

2003-01-01

The formation and fate of soluble microbial products (SMP) in membrane bioreactor (MBR) was investigated at various sludge retention times (SRT) for 170 days. The SMP concentration was estimated by feeding glucose, which could be completely degraded, and by measuring the dissolved organic carbon (DOC) of the effluent from MBR. Under the conditions of SRT of 20 days, influent DOC of 112 mg/l and HRT of 6 h, the produced SMP was 4.7 mg DOC/l of which 57% was removed or retained by the membrane. DOC of MBR supernatant increased during 100 days and then gradually decreased. Specific UV absorbance showed that the accumulated compounds had a portion of larger, more aromatic, more hydrophobic and double-bond-rich organics, which originated from the decayed biomass. Molecular weight distributions of SMP in MBR supernatant showed that the acclimated microorganisms in a long SRT could decompose high molecular weight organics, it caused the shift of molecular weight distributions of SMP to a lower range. During the operation period, enumeration of active cells in the MBR showed that microbial inhibitions by accumulated SMP was not observed.

Simulation of a porous ceramic membrane reactor for hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Yu, W.; Ohmori, T.; Yamamoto, T.; Endo, A.; Nakaiwa, M.; Hayakawa, T. [National Inst. of Advanced Industrial Science and Technology, Tsukuba (Japan); Itoh, N. [National Inst. of Advanced Industrial Science and Technology, Tsukuba (Japan); Utsunomiya Univ. (Japan). Dept. of Applied Chemistry

2005-08-01

A systematic simulation study was performed to investigate the performance of a porous ceramic membrane reactor for hydrogen production by means of methane steam reforming. The results show that the methane conversions much higher than the corresponding equilibrium values can be achieved in the membrane reactor due to the selective removal of products from the reaction zone. The comparison of isothermal and non-isothermal model predictions was made. It was found that the isothermal assumption overestimates the reactor performance and the deviation of calculation results between the two models is subject to the operating conditions. The effects of various process parameters such as the reaction temperature, the reaction side pressure, the feed flow rate and the steam to methane molar feed ratio as well as the sweep gas flow rate and the operation modes, on the behavior of membrane reactor were analyzed and discussed. (author)

Nanofiltration and Tight Ultrafiltration Membranes for the Recovery of Polyphenols from Agro-Food By-Products

Directory of Open Access Journals (Sweden)

Alfredo Cassano

2018-01-01

Full Text Available Pressure-driven membrane-based technologies represent a valid approach to reduce the environmental pollution of several agro-food by-products. Recently, in relation to the major interest for natural compounds with biological activities, their use has been also addressed to the recovery, separation and fractionation of phenolic compounds from such by-products. In particular, tight ultrafiltration (UF and nanolfiltration (NF membranes have been recognized for their capability to recover phenolic compounds from several types of agro-food by-products. The separation capability of these membranes, as well as their productivity, depends on multiple factors such as membrane material, molecular weight cut-off (MWCO and operating conditions (e.g., pressure, temperature, feed flow rate, volume reduction factor, etc.. This paper aims at providing a critical overview of the influence of these parameters on the recovery of phenolic compounds from agro-food by-products by using tight UF and NF membranes. The literature data are analyzed and discussed in relation to separation processes, molecule properties, membrane characteristics and other phenomena occurring in the process. Current extraction methodologies of phenolic compounds from raw materials are also introduced in order to drive the implementation of integrated systems for the production of actractive phenolic formulations of potential interest as food antioxidants.

Nanofiltration and Tight Ultrafiltration Membranes for the Recovery of Polyphenols from Agro-Food By-Products.

Science.gov (United States)

Cassano, Alfredo; Conidi, Carmela; Ruby-Figueroa, René; Castro-Muñoz, Roberto

2018-01-24

Pressure-driven membrane-based technologies represent a valid approach to reduce the environmental pollution of several agro-food by-products. Recently, in relation to the major interest for natural compounds with biological activities, their use has been also addressed to the recovery, separation and fractionation of phenolic compounds from such by-products. In particular, tight ultrafiltration (UF) and nanolfiltration (NF) membranes have been recognized for their capability to recover phenolic compounds from several types of agro-food by-products. The separation capability of these membranes, as well as their productivity, depends on multiple factors such as membrane material, molecular weight cut-off (MWCO) and operating conditions (e.g., pressure, temperature, feed flow rate, volume reduction factor, etc.). This paper aims at providing a critical overview of the influence of these parameters on the recovery of phenolic compounds from agro-food by-products by using tight UF and NF membranes. The literature data are analyzed and discussed in relation to separation processes, molecule properties, membrane characteristics and other phenomena occurring in the process. Current extraction methodologies of phenolic compounds from raw materials are also introduced in order to drive the implementation of integrated systems for the production of actractive phenolic formulations of potential interest as food antioxidants.

Degradation of the pharmaceuticals diclofenac and sulfamethoxazole and their transformation products under controlled environmental conditions

International Nuclear Information System (INIS)

Poirier-Larabie, S.; Segura, P.A.; Gagnon, C.

2016-01-01

Contamination of the aquatic environment by pharmaceuticals via urban effluents is well known. Several classes of drugs have been identified in waterways surrounding these effluents in the last 15 years. To better understand the fate of pharmaceuticals in ecosystems, degradation processes need to be investigated and transformation products must be identified. Thus, this study presents the first comparative study between three different natural environmental conditions: photolysis and biodegradation in aerobic and anaerobic conditions both in the dark of diclofenac and sulfamethoxazole, two common drugs present in significant amounts in impacted surface waters. Results indicated that degradation kinetics differed depending on the process and the type of drug and the observed transformation products also differed among these exposure conditions. Diclofenac was nearly degraded by photolysis after 4 days, while its concentration only decreased by 42% after 57 days of exposure to bacteria in aerobic media and barely 1% in anaerobic media. For sulfamethoxazole, 84% of the initial concentration was still present after 11 days of exposure to light, while biodegradation decreased its concentration by 33% after 58 days of exposure under aerobic conditions and 5% after 70 days of anaerobic exposure. In addition, several transformation products were observed and persisted over time while others degraded in turn. For diclofenac, chlorine atoms were lost primarily in the photolysis, while a redox reaction was promoted by biodegradation under aerobic conditions. For sulfamethoxazole, isomerization was favored by photolysis while a redox reaction was also favored by the biodegradation under aerobic conditions. To summarize this study points out the occurrence of different transformation products under variable degradation conditions and demonstrates that specific functional groups are involved in the tested natural attenuation processes. Given the complexity of environmental

Degradation of the pharmaceuticals diclofenac and sulfamethoxazole and their transformation products under controlled environmental conditions

Energy Technology Data Exchange (ETDEWEB)

Poirier-Larabie, S. [Aquatic Contaminants Research Division, Science and Water Technology Directorate, Environment Canada, Montréal, Québec H2Y 2E7 (Canada); Segura, P.A. [Department of Chemistry, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1 (Canada); Gagnon, C., E-mail: christian.gagnon@canada.ca [Aquatic Contaminants Research Division, Science and Water Technology Directorate, Environment Canada, Montréal, Québec H2Y 2E7 (Canada)

2016-07-01

Contamination of the aquatic environment by pharmaceuticals via urban effluents is well known. Several classes of drugs have been identified in waterways surrounding these effluents in the last 15 years. To better understand the fate of pharmaceuticals in ecosystems, degradation processes need to be investigated and transformation products must be identified. Thus, this study presents the first comparative study between three different natural environmental conditions: photolysis and biodegradation in aerobic and anaerobic conditions both in the dark of diclofenac and sulfamethoxazole, two common drugs present in significant amounts in impacted surface waters. Results indicated that degradation kinetics differed depending on the process and the type of drug and the observed transformation products also differed among these exposure conditions. Diclofenac was nearly degraded by photolysis after 4 days, while its concentration only decreased by 42% after 57 days of exposure to bacteria in aerobic media and barely 1% in anaerobic media. For sulfamethoxazole, 84% of the initial concentration was still present after 11 days of exposure to light, while biodegradation decreased its concentration by 33% after 58 days of exposure under aerobic conditions and 5% after 70 days of anaerobic exposure. In addition, several transformation products were observed and persisted over time while others degraded in turn. For diclofenac, chlorine atoms were lost primarily in the photolysis, while a redox reaction was promoted by biodegradation under aerobic conditions. For sulfamethoxazole, isomerization was favored by photolysis while a redox reaction was also favored by the biodegradation under aerobic conditions. To summarize this study points out the occurrence of different transformation products under variable degradation conditions and demonstrates that specific functional groups are involved in the tested natural attenuation processes. Given the complexity of environmental

The Impact of Charcoal Production on Forest Degradation: a Case Study in Tete, Mozambique

Science.gov (United States)

Sedano, F.; Silva. J. A.; Machoco, R.; Meque, C. H.; Sitoe, A.; Ribeiro, N.; Anderson, K.; Ombe, Z. A.; Baule, S. H.; Tucker, C. J.

2016-01-01

Charcoal production for urban energy consumption is a main driver of forest degradation in sub-Saharan Africa. Urban growth projections for the continent suggest that the relevance of this process will increase in the coming decades. Forest degradation associated to charcoal production is difficult to monitor and commonly overlooked and underrepresented in forest cover change and carbon emission estimates. We use a multi-temporal dataset of very high-resolution remote sensing images to map kiln locations in a representative study area of tropical woodlands in central Mozambique. The resulting maps provided a characterization of the spatial extent and temporal dynamics of charcoal production. Using an indirect approach we combine kiln maps and field information on charcoal making to describe the magnitude and intensity of forest degradation linked to charcoal production, including aboveground biomass and carbon emissions. Our findings reveal that forest degradation associated to charcoal production in the study area is largely independent from deforestation driven by agricultural expansion and that its impact on forest cover change is in the same order of magnitude as deforestation. Our work illustrates the feasibility of using estimates of urban charcoal consumption to establish a link between urban energy demands and forest degradation. This kind of approach has potential to reduce uncertainties in forest cover change and carbon emission assessments in sub-Saharan Africa.

Production of hydrogen from bio-ethanol in catalytic membrane reactor

International Nuclear Information System (INIS)

Gernot, E.; Aupretre, F.; Deschamps, A.; Etievant, C.; Epron, F.; Marecot, P.; Duprez, D.

2006-01-01

Production of hydrogen from renewable energy sources offers a great potential for CO 2 emission reduction, responsible for global warming. Among renewable energies, liquid biofuels are very convenient hydrogen carriers for decentralized applications such as micro-cogeneration and transports. Ethanol, produced from sugar plants and cereals, allows a reduction of more than 60% of CO 2 emissions in comparison to gasoline. BIOSTAR is an R and D project, co-funded by the French Agency for Environment and Energy Management (ADEME) which aims at developing an efficient source of hydrogen from bio-ethanol, suitable for proton exchange membrane fuel cell systems. The objectives are to obtain, through catalytic process at medium temperature range, an efficient conversion of bio-ethanol into pure hydrogen directly usable for PEMFC. CETH has developed a catalytic membrane reformer (CMR), based on a patented technology, integrating a steam reforming catalyst as well as a combustion catalyst. Both catalysts have been developed and optimized for membrane reactor in partnership with the University of Poitiers. The composite metallic membrane developed by CETH allows hydrogen extraction near the hydrogen production sites, which enhances both efficiency and compactness. (authors)

Diesel degradation and biosurfactant production by Gram-positive ...

African Journals Online (AJOL)

The ability of Gram-positive bacteria to degrade diesel increased in a comparable trend as its biosurfactant production increased. The E24 index was highest at 87.6% for isolate D9. Isolates D2, D9 and D10, were identified as Paenibacillus sp. whilst isolate DJLB was found to belong to Stenotrophomonas sp. This study ...

Quantitative analysis of Loperamide hydrochloride in the presence its acid degradation products

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Savić Ivana M.

2009-01-01

Full Text Available The aim of this work was to develop a new RP-HPLC method for the determination of loperamide hydrochloride in the presence of its acid degradation products. Separation of loperamide from degradation products was performed using ZORBAX Eclipse XDB C-18, column with a mobile phase consisting of 0.1% sodium-octansulphonate, 0.05% triethylamine, 0.1% ammonium hydroxide in water:acetonitrile (45:55 v/v. The mobile phase was adjusted to pH 3.2 with phosphoric acid. The method showed high sensitivity with good linearity over the concentration range of 10 to 100 μg cm-3. The method was successfully applied to the analysis of a pharmaceutical formulation (Loperamide, Zdravlje-Actavis, Serbia containing loperamide hydrochloride with excellent recovery. The loperamide hydrochloride degradation during acid hydrolysis and kinetics investigation was carried out in hydrochloric acid solutions of 0.1, 1.0 and 1.5 mol dm-3, at different temperatures (25 and 40°C, by monitoring the parent compound itself. The first order reaction of loperamide degradation in acid solution was determined. The activation energy was estimated from the Arrhenius plot and it was found to be 38.81 kJ mol-1 at 40°C. The developed procedure was successfully applied for the rapid determination of loperamide hydrochloride in pharmaceutical formulation (Loperamide, Zdravlje-Actavis, Serbia and in the presence of its acid degradation products.

The degradation of lining of rotary furnaces in the production of zinc oxide

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Natália Luptáková

2014-06-01

Full Text Available This paper is closely connected with the complex problem of degradation relating to the refractories of rotary furnace linings in the production of zinc oxide. Zinc oxide can be produced by variety of ways, but the most common method of production which is used in Europe is indirect, i.e. pyrolytic combustion of zinc. This method is also called "French process" of manufacturing ZnO. But this mentioned method of preparation leads to the creation of the enormous amount of zinc slag including chemical complexes of elements Fe, Zn and Al. The mechanism of degradation of the lining leads to slag rests and it is closely connected with the mutual interaction of the aggressive agents with the components of the lining. This process creates a new undesired surface layer which increased the overall thickness of zinc slag. Stuck slag has the influence on rapid degradation of the linings and moreover it also decreases the production quality of ZnO. Analysis results introduced in this paper are significant information for minimizing of degradation of rotary furnaces.  

Novel chromatographic separation and carbon solid-phase extraction of acetanilide herbicide degradation products.

Science.gov (United States)

Shoemaker, Jody A

2002-01-01

One acetamide and 5 acetanilide herbicides are currently registered for use in the United States. Over the past several years, ethanesulfonic acid (ESA) and oxanilic acid (OA) degradation products of these acetanilide/acetamide herbicides have been found in U.S. ground waters and surface waters. Alachlor ESA and other acetanilide degradation products are listed on the U.S. Environmental Protection Agency's (EPA) 1998 Drinking Water Contaminant Candidate List. Consequently, EPA is interested in obtaining national occurrence data for these contaminants in drinking water. EPA currently does not have a method for determining these acetanilide degradation products in drinking water; therefore, a research method is being developed using liquid chromatography/negative ion electrospray/mass spectrometry with solid-phase extraction (SPE). A novel chromatographic separation of the acetochlor/alachlor ESA and OA structural isomers was developed which uses an ammonium acetate-methanol gradient combined with heating the analytical column to 70 degrees C. Twelve acetanilide degradates were extracted by SPE from 100 mL water samples using carbon cartridges with mean recoveries >90% and relative standard deviations < or =16%.

Mitigation of membrane biofouling by a quorum quenching bacterium for membrane bioreactors.

Science.gov (United States)

Ham, So-Young; Kim, Han-Shin; Cha, Eunji; Park, Jeong-Hoon; Park, Hee-Deung

2018-06-01

In this study, a quorum-quenching (QQ) bacterium named HEMM-1 was isolated at a membrane bioreactor (MBR) plant. HEMM-1 has diplococcal morphology and 99% sequence identity to Enterococcus species. The HEMM-1 cell-free supernatant (CFS) showed higher QQ activities than the CFS of other QQ bacteria, mostly by degrading N-acyl homoserine lactones (AHLs) with short acyl chains. Instrumental analyses revealed that HEMM-1 CFS degraded AHLs via lactonase activity. Under static, flow, and shear conditions, the HEMM-1 CFS was effective in reducing bacterial and activated-sludge biofilms formed on membrane surfaces. In conclusion, the HEMM-1 isolate is a QQ bacterium applicable to the control of biofouling in MBRs via inhibition of biofilm formation on membrane surfaces. Copyright © 2018 Elsevier Ltd. All rights reserved.

Membrane bioreactors for waste gas treatment.

NARCIS (Netherlands)

Reij, M.W.; Keurentjes, J.T.F.; Hartmans, S.

1998-01-01

This review describes the recent development of membrane reactors for biological treatment of waste gases. In this type of bioreactor gaseous pollutants are transferred through a membrane to the liquid phase, where micro-organisms degrade the pollutants. The membrane bioreactor combines the

Membrane bioreactors for waste gas treatment

NARCIS (Netherlands)

Reij, M.W.; Keurentjes, J.T.F.; Hartmans, S.

1998-01-01

This review describes the recent development of membrane reactors for biological treatment of waste gases. In this type of bioreactor gaseous pollutants are transferred through a membrane to the liquid phase, where micro-organisms degrade the pollutants. The membrane bioreactor combines the

Time extrapolation of radiolytic degradation product kinetics: the case of polyurethane

International Nuclear Information System (INIS)

Dannoux, A.

2007-02-01

The prediction of the environmental impact of organic materials in nuclear waste geological storage needs knowledge of radiolytic degradation mechanisms and kinetics in aerobic and anaerobic conditions. In this framework, the effect of high doses (> MGy) and the variation of dose rate have to be considered. The material studied is a polyurethane composed of polyether soft segment and aromatic hard segments. Mechanisms were built on the analysis of material submitted to irradiations of simulation (high energy electrons and gamma radiation) by FTIR spectroscopy and gaseous and liquid degradation products by gas mass spectrometry and size exclusion chromatography. The electron paramagnetic resonance study of radical process and the determination of oxygen consumption and gas formation radiolytic yields allowed us to acquire kinetic data and to estimate dose rate and high doses effects. The polyurethane radio-oxidation mainly concerns soft segments and induced cross-linkings and production by scissions of oxidised compounds (esters, alcohols, carboxylic acids). The kinetic of radical termination is rapid and the dose rate effect is limited. After 10 MGy, branching and scission reactions are in equilibrium and low molecular weight products accumulate. At last, the degradation products release in water is influenced by the oxidation rate and the temperature. After 10 MGy, the soluble fraction is stabilised at 25%. The water soluble products identified by electro-spray ionisation mass spectrometry (alcohols, aldehydes, carboxylic acids) potentially formed complexes with radionuclides. (author)

Reticulophagy and Ribophagy: Regulated Degradation of Protein Production Factories

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Eduardo Cebollero

2012-01-01

Full Text Available During autophagy, cytosol, protein aggregates, and organelles are sequestered into double-membrane vesicles called autophagosomes and delivered to the lysosome/vacuole for breakdown and recycling of their basic components. In all eukaryotes this pathway is important for adaptation to stress conditions such as nutrient deprivation, as well as to regulate intracellular homeostasis by adjusting organelle number and clearing damaged structures. For a long time, starvation-induced autophagy has been viewed as a nonselective transport pathway; however, recent studies have revealed that autophagy is able to selectively engulf specific structures, ranging from proteins to entire organelles. In this paper, we discuss recent findings on the mechanisms and physiological implications of two selective types of autophagy: ribophagy, the specific degradation of ribosomes, and reticulophagy, the selective elimination of portions of the ER.

Carbon-coated ceramic membrane reactor for the production of hydrogen by aqueous-phase reforming of sorbitol.

Science.gov (United States)

Neira D'Angelo, M F; Ordomsky, V; Schouten, J C; van der Schaaf, J; Nijhuis, T A

2014-07-01

Hydrogen was produced by aqueous-phase reforming (APR) of sorbitol in a carbon-on-alumina tubular membrane reactor (4 nm pore size, 7 cm long, 3 mm internal diameter) that allows the hydrogen gas to permeate to the shell side, whereas the liquid remains in the tube side. The hydrophobic nature of the membrane serves to avoid water loss and to minimize the interaction between the ceramic support and water, thus reducing the risks of membrane degradation upon operation. The permeation of hydrogen is dominated by the diffusivity of the hydrogen in water. Thus, higher operation temperatures result in an increase of the flux of hydrogen. The differential pressure has a negative effect on the flux of hydrogen due to the presence of liquid in the larger pores. The membrane was suitable for use in APR, and yielded 2.5 times more hydrogen than a reference reactor (with no membrane). Removal of hydrogen through the membrane assists in the reaction by preventing its consumption in undesired reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Repeated batch and continuous degradation of chlorpyrifos by Pseudomonas putida.

Science.gov (United States)

Pradeep, Vijayalakshmi; Subbaiah, Usha Malavalli

2015-01-01

The present study was undertaken with the objective of studying repeated batch and continuous degradation of chlorpyrifos (O,O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) using Ca-alginate immobilized cells of Pseudomonas putida isolated from an agricultural soil, and to study the genes and enzymes involved in degradation. The study was carried out to reduce the toxicity of chlorpyrifos by degrading it to less toxic metabolites. Long-term stability of pesticide degradation was studied during repeated batch degradation of chlorpyrifos, which was carried out over a period of 50 days. Immobilized cells were able to show 65% degradation of chlorpyrifos at the end of the 50th cycle with a cell leakage of 112 × 10(3) cfu mL(-1). During continuous treatment, 100% degradation was observed at 100 mL h(-1) flow rate with 2% chlorpyrifos, and with 10% concentration of chlorpyrifos 98% and 80% degradation was recorded at 20 mL h(-1) and 100 mL h(-1) flow rate respectively. The products of degradation detected by liquid chromatography-mass spectrometry analysis were 3,5,6-trichloro-2-pyridinol and chlorpyrifos oxon. Plasmid curing experiments with ethidium bromide indicated that genes responsible for the degradation of chlorpyrifos are present on the chromosome and not on the plasmid. The results of Polymerase chain reaction indicate that a ~890-bp product expected for mpd gene was present in Ps. putida. Enzymatic degradation studies indicated that the enzymes involved in the degradation of chlorpyrifos are membrane-bound. The study indicates that immobilized cells of Ps. putida have the potential to be used in bioremediation of water contaminated with chlorpyrifos.

Study of the Effect of Nanoparticles and Surface Morphology on Reverse Osmosis and Nanofiltration Membrane Productivity

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Steven J. Duranceau

2013-08-01

Full Text Available To evaluate the significance of reverse osmosis (RO and nanofiltration (NF surface morphology on membrane performance, productivity experiments were conducted using flat-sheet membranes and three different nanoparticles, which included SiO2, TiO2 and CeO2. In this study, the productivity rate was markedly influenced by membrane surface morphology. Atomic force microscopy (AFM analysis of membrane surfaces revealed that the higher productivity decline rates associated with polyamide RO membranes as compared to that of a cellulose acetate NF membrane was due to the inherent ridge-and-valley morphology of the active layer. The unique polyamide active layer morphology was directly related to the surface roughness, and was found to contribute to particle accumulation in the valleys causing a higher flux decline than in smoother membranes. Extended RO productivity experiments using laboratory grade water and diluted pretreated seawater were conducted to compare the effect that different nanoparticles had on membrane active layers. Membrane flux decline was not affected by particle type when the feed water was laboratory grade water. On the other hand, membrane productivity was affected by particle type when pretreated diluted seawater served as feed water. It was found that CeO2 addition resulted in the least observable flux decline, followed by SiO2 and TiO2. A productivity simulation was conducted by fitting the monitored flux data into a cake growth rate model, where the model was modified using a finite difference method to incorporate surface thickness variation into the analysis. The ratio of cake growth term (k1 and particle back diffusion term (k2 was compared in between different RO and NF membranes. Results indicated that k2 was less significant for surfaces that exhibited a higher roughness. It was concluded that the valley areas of thin-film membrane surfaces have the ability to capture particles, limiting particle back diffusion.

Microbial transformation of biomacromolecules in a membrane bioreactor: implications for membrane fouling investigation.

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Zhongbo Zhou

Full Text Available BACKGROUND: The complex characteristics and unclear biological fate of biomacromolecules (BMM, including colloidal and soluble microbial products (SMP, extracellular polymeric substances (EPS and membrane surface foulants (MSF, are crucial factors that limit our understanding of membrane fouling in membrane bioreactors (MBRs. FINDINGS: In this study, the microbial transformation of BMM was investigated in a lab-scale MBR by well-controlled bioassay tests. The results of experimental measurements and mathematical modeling show that SMP, EPS, and MSF had different biodegradation behaviors and kinetic models. Based on the multi-exponential G models, SMP were mainly composed of slowly biodegradable polysaccharides (PS, proteins (PN, and non-biodegradable humic substances (HS. In contrast, EPS contained a large number of readily biodegradable PN, slowly biodegradable PS and HS. MSF were dominated by slowly biodegradable PS, which had a degradation rate constant similar to that of SMP-PS, while degradation behaviors of MSF-PN and MSF-HS were much more similar to those of EPS-PN and EPS-HS, respectively. In addition, the large-molecular weight (MW compounds (>100 kDa in BMM were found to have a faster microbial transformation rate compared to the small-MW compounds (<5 kDa. The parallel factor (PARAFAC modeling of three-dimensional fluorescence excitation-emission matrix (EEM spectra showed that the tryptophan-like PN were one of the major fractions in the BMM and they were more readily biodegradable than the HS. Besides microbial mineralization, humification and hydrolysis could be viewed as two important biotransformation mechanisms of large-MW compounds during the biodegradation process. SIGNIFICANCE: The results of this work can aid in tracking the origin of membrane foulants from the perspective of the biotransformation behaviors of SMP, EPS, and MSF.

Advances of zeolite based membrane for hydrogen production via water gas shift reaction

Science.gov (United States)

Makertihartha, I. G. B. N.; Zunita, M.; Rizki, Z.; Dharmawijaya, P. T.

2017-07-01

Hydrogen is considered as a promising energy vector which can be obtained from various renewable sources. However, an efficient hydrogen production technology is still challenging. One technology to produce hydrogen with very high capacity with low cost is through water gas shift (WGS) reaction. Water gas shift reaction is an equilibrium reaction that produces hydrogen from syngas mixture by the introduction of steam. Conventional WGS reaction employs two or more reactors in series with inter-cooling to maximize conversion for a given volume of catalyst. Membrane reactor as new technology can cope several drawbacks of conventional reactor by removing reaction product and the reaction will favour towards product formation. Zeolite has properties namely high temperature, chemical resistant, and low price makes it suitable for membrane reactor applications. Moreover, it has been employed for years as hydrogen selective layer. This review paper is focusing on the development of membrane reactor for efficient water gas shift reaction to produce high purity hydrogen and carbon dioxide. Development of membrane reactor is discussed further related to its modification towards efficient reaction and separation from WGS reaction mixture. Moreover, zeolite framework suitable for WGS membrane reactor will be discussed more deeply.

Online Monitoring of Electrochemical Degradation of Paracetamol through a Biomimetic Sensor

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Mariana Calora Quintino de Oliveira

2011-01-01

Full Text Available This paper reports, for the first time, the online monitoring to the electrochemical degradation of the paracetamol using a biomimetic sensor coupled to a Flow Injection Analysis (FIA system. The electrochemical degradation of the drug was carried out in aqueous medium using a flow-by reactor with a DSA anode. The process efficiency was monitored at real time by the biomimetic sensor constructed by modifying a glassy carbon electrode with a Nafion membrane doped with iron tetrapyridinoporphyrazine (FeTPyPz. Simultaneously, we carried out off-line analysis by liquid chromatography (HPLC during the experiments in order to validate the proposed system. In addition, to investigate the degradation products of the paracetamol electrolysis, we used the techniques of UPLC/MS and GC/MS.

Degradation pathway of malachite green in a novel dual-tank photoelectrochemical catalytic reactor

International Nuclear Information System (INIS)

Diao, Zenghui; Li, Mingyu; Zeng, Fanyin; Song, Lin; Qiu, Rongliang

2013-01-01

Highlights: • A novel dual-tank photoelectrochemical catalytic reactor was designed. • Malachite green degraded in bipolar double-effect mode. • Salt bridge replaced by a cation exchange membrane in the reactor. • Degradation pathways of malachite green in the cathode and anode tanks were similar. -- Abstract: A novel dual-tank photoelectrochemical catalytic reactor was designed to investigate the degradation pathway of malachite green. A thermally formed TiO 2 /Ti thin film electrode was used as photoanode, graphite was used as cathode, and a saturated calomel electrode was employed as the reference electrode in the reactor. In the reactor, the anode and cathode tanks were connected by a cation exchange membrane. Results showed that the decolorization ratio of malachite green in the anode and cathode was 98.5 and 96.5% after 120 min, respectively. Malachite green in the two anode and cathode tanks was oxidized, achieving the bipolar double effect. Malachite green in both the anode and cathode tanks exhibited similar catalytic degradation pathways. The double bond of the malachite green molecule was attacked by strong oxidative hydroxyl radicals, after which the organic compound was degraded by the two pathways into 4,4-bis(dimethylamino) benzophenone, 4-(dimethylamino) benzophenone, 4-(dimethylamino) phenol, and other intermediate products. Eventually, malachite green was degraded into oxalic acid as a small molecular organic acid, which was degraded by processes such as demethylation, deamination, nitration, substitution, addition, and other reactions

Halotolerance, ligninase production and herbicide degradation ability of basidiomycetes strains

Directory of Open Access Journals (Sweden)

R.L. Arakaki

2013-12-01

Full Text Available Fungi have been recently recognized as organisms able to grow in presence of high salt concentration with halophilic and halotolerance properties and their ligninolytic enzyme complex have an unspecific action enabling their use to degradation of a number of xenobiotic compounds. In this work, both the effect of salt and polyols on growth of the basidiomycetes strains, on their ability to produce ligninolytic enzyme and diuron degradation were evaluated. Results showed that the presence of NaCl in the culture medium affected fungal specimens in different ways. Seven out of ten tested strains had growth inhibited by salt while Dacryopinax elegans SXS323, Polyporus sp MCA128 and Datronia stereoides MCA167 fungi exhibited higher biomass production in medium containing 0.5 and 0.6 mol.L-1 of NaCl, suggesting to be halotolerant. Polyols such as glycerol and mannitol added into the culture media improved the biomass and ligninases production by D. elegans but the fungus did not reveal consumption of these polyols from media. This fungus degraded diuron in medium control, in presence of NaCl as well as polyols, produced MnP, LiP and laccase.

Halotolerance, ligninase production and herbicide degradation ability of basidiomycetes strains.

Science.gov (United States)

Arakaki, R L; Monteiro, D A; Boscolo, M; Dasilva, R; Gomes, E

2013-12-01

Fungi have been recently recognized as organisms able to grow in presence of high salt concentration with halophilic and halotolerance properties and their ligninolytic enzyme complex have an unspecific action enabling their use to degradation of a number of xenobiotic compounds. In this work, both the effect of salt and polyols on growth of the basidiomycetes strains, on their ability to produce ligninolytic enzyme and diuron degradation were evaluated. Results showed that the presence of NaCl in the culture medium affected fungal specimens in different ways. Seven out of ten tested strains had growth inhibited by salt while Dacryopinax elegans SXS323, Polyporus sp MCA128 and Datronia stereoides MCA167 fungi exhibited higher biomass production in medium containing 0.5 and 0.6 mol.L(-1) of NaCl, suggesting to be halotolerant. Polyols such as glycerol and mannitol added into the culture media improved the biomass and ligninases production by D. elegans but the fungus did not reveal consumption of these polyols from media. This fungus degraded diuron in medium control, in presence of NaCl as well as polyols, produced MnP, LiP and laccase.

Alternate Fuel Cell Membranes for Energy Independence

Energy Technology Data Exchange (ETDEWEB)

Storey, Robson, F.; Mauritz, Kenneth, A.; Patton, Derek, L.; Savin, Daniel, A.

2012-12-18

performance properties of experimental membranes, 9) fabrication and FC performance testing of membrane electrode assemblies (MEA) from experimental membranes, and 10) measurement of ex situ and in situ membrane durability of experimental membranes. Although none of the experimental hydrocarbon membranes that issued from the project displayed proton conductivities that met DOE requirements, the project contributed to our basic understanding of membrane structure-property relationships in a number of key respects. An important finding of the benchmark studies is that physical degradation associated with humidity and temperature variations in the FC tend to open new fuel crossover pathways and act synergistically with chemical degradation to accelerate overall membrane degradation. Thus, for long term membrane survival and efficient fuel utilization, membranes must withstand internal stresses due to humidity and temperature changes. In this respect, rigid aromatic hydrocarbon fuel cell membranes, e.g. PAES, offer an advantage over un-modified Nafion membranes. The benchmark studies also showed that broadband dielectric spectroscopy is a potentially powerful tool in assessing shifts in the fundamental macromolecular dynamics caused by Nafion chemical degradation, and thus, this technique is of relevance in interrogating proton exchange membrane durability in fuel cells and macromolecular dynamics as coupled to proton migration, which is of fundamental relevance in proton exchange membranes in fuel cells. A key finding from the hydrocarbon membrane synthesis effort was that rigid aromatic polymers containing isolated ion exchange groups tethered tightly to the backbone (short tether), such as HPPS, provide excellent mechanical and durability properties but do not provide sufficient conductivity, in either random or block configuration, when used as the sole ion exchange monomer. However, we continue to hypothesize that longer tethers, and tethered groups spaced more closely

Model for Stress-induced Protein Degradation in Lemna minor1

Science.gov (United States)

Cooke, Robert J.; Roberts, Keith; Davies, David D.

1980-01-01

Transfer of Lemna minor fronds to adverse or stress conditions produces a large increase in the rate of protein degradation. Cycloheximide partially inhibits stress-induced protein degradation and also partially inhibits the protein degradation which occurs in the absence of stress. The increased protein degradation does not appear to be due to an increase in activity of soluble proteolytic enzymes. Biochemical evidence indicates that stress, perhaps acting via hormones, affects the permeability of certain membranes, particularly the tonoplast. A general model for stress-induced protein degradation is presented in which changes in membrane properties allow vacuolar proteolytic enzymes increased access to cytoplasmic proteins. PMID:16661588

Studies on membrane acid electrolysis for hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Silva, Marco Antonio Oliveira da; Linardi, Marcelo; Saliba-Silva, Adonis Marcelo [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Celulas a Combustivel e Hidrogenio], Email: saliba@ipen.br

2010-07-01

Hydrogen represents great opportunity to be a substitute for fossil fuels in the future. Water as a renewable source of hydrogen is of great interest, since it is abundant and can decompose, producing only pure H{sub 2} and O{sub 2}. This decomposition of water can be accomplished by processes such as electrolysis, thermal decomposition and thermochemical cycles. The electrolysis by membrane has been proposed as a viable process for hydrogen production using thermal and electrical energy derived from nuclear energy or any renewable source like solar energy. In this work, within the context of optimization of the electrolysis process, it is intended to develop a mathematical model that can simulate and assist in parameterization of the electrolysis performed by polymer membrane electrolytic cell. The experimental process to produce hydrogen via the cell membrane, aims to optimize the amount of gas produced using renewable energy with noncarbogenic causing no harm by producing gases deleterious to the environment. (author)

Development of a Novel Degradation-Controlled Magnesium-Based Regeneration Membrane for Future Guided Bone Regeneration (GBR Therapy

Directory of Open Access Journals (Sweden)

Da-Jun Lin

2017-11-01

Full Text Available This study aimed to develop and evaluate the ECO-friendly Mg-5Zn-0.5Zr (ECO505 alloy for application in dental-guided bone regeneration (GBR. The microstructure and surface properties of biomedical Mg materials greatly influence anti-corrosion performance and biocompatibility. Accordingly, for the purpose of microstructure and surface modification, heat treatments and surface coatings were chosen to provide varied functional characteristics. We developed and integrated both an optimized solution heat-treatment condition and surface fluoride coating technique to fabricate a Mg-based regeneration membrane. The heat-treated Mg regeneration membrane (ARRm-H380 and duplex-treated regeneration membrane group (ARRm-H380-F24 h were thoroughly investigated to characterize the mechanical properties, as well as the in vitro corrosion and in vivo degradation behaviors. Significant enhancement in ductility and corrosion resistance for the ARRm-H380 was obtained through the optimized solid-solution heat treatment; meanwhile, the corrosion resistance of ARRm-H380-F24 h showed further improvement, resulting in superior substrate integrity. In addition, the ARRm-H380 provided the proper amount of Mg-ion concentration to accelerate bone growth in the early stage (more than 80% new bone formation. From a specific biomedical application point of view, these research results point out a successful manufacturing route and suggest that the heat treatment and duplex treatment could be employed to offer custom functional regeneration membranes for different clinical patients.

Current strategies for protein production and purification enabling membrane protein structural biology.

Science.gov (United States)

Pandey, Aditya; Shin, Kyungsoo; Patterson, Robin E; Liu, Xiang-Qin; Rainey, Jan K

2016-12-01

Membrane proteins are still heavily under-represented in the protein data bank (PDB), owing to multiple bottlenecks. The typical low abundance of membrane proteins in their natural hosts makes it necessary to overexpress these proteins either in heterologous systems or through in vitro translation/cell-free expression. Heterologous expression of proteins, in turn, leads to multiple obstacles, owing to the unpredictability of compatibility of the target protein for expression in a given host. The highly hydrophobic and (or) amphipathic nature of membrane proteins also leads to challenges in producing a homogeneous, stable, and pure sample for structural studies. Circumventing these hurdles has become possible through the introduction of novel protein production protocols; efficient protein isolation and sample preparation methods; and, improvement in hardware and software for structural characterization. Combined, these advances have made the past 10-15 years very exciting and eventful for the field of membrane protein structural biology, with an exponential growth in the number of solved membrane protein structures. In this review, we focus on both the advances and diversity of protein production and purification methods that have allowed this growth in structural knowledge of membrane proteins through X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and cryo-electron microscopy (cryo-EM).

PRODUCTION AND RECOVERY OF POLY-Β-HYDROXYBUTYRATE FROM WHEY DEGRADATION BY AZOTOBACTER

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A. Khanafari , A. Akhavan Sepahei, M. Mogharab

2006-07-01

Full Text Available Three strains of Azotobacter chroococcum were studied to produce poly-β hydroxybutyrate as a inclusion body by whey degradation. Optimum degradation whey results were obtained when using whey broth as a fermentation medium without extra salt, temperature at 35 °C and pH 7 (P<0.05. Lambda max for whey broth medium was determined probably about 400 nm. The effect of different nitrogenous rich compounds (NH4NO3, Bactopeptone, Casein, Yeast extract, Meat extract, Protease peptone and Tryptone on whey degradation showed that incorporation of nitrogenous compounds into the medium did not increase whey degradation by Azotobacter chroococcum 1723 (P<0.05. But poly-β hydroxyl-butyrate production was increased in presence Meat extract up to 75% of the cell dry weight after 48h. The addition of nitrogenous sourced (except ammonium nitrate had a positive effect on poly-β hydroxyl-butyrate production as it peaked in the presence of Meat extract and 4.43 g/L was accumulated in comparison to 0.5g at diazotrophically growing cells. Increasing the O2 values resulted by shaking at 122 rpm in decreased poly-β hydroxyl-butyrate yield form 4.43 to 0.04 g/L. The results show that this medium supports the growth of strain 1735 and also that this waste could be utilized as a carbon and nitrogen source. Production of poly-β hydroxyl-butyrate by using whey as a medium looks promising, since the use of inexpensive feed-stocks for poly-β hydroxyl-butyrate is essential if bioplastics are to become competitive products.

A validated stability-indicating RP-HPLC method for levofloxacin in the presence of degradation products, its process related impurities and identification of oxidative degradant.

Science.gov (United States)

Lalitha Devi, M; Chandrasekhar, K B

2009-12-05

The objective of current study was to develop a validated specific stability indicating reversed-phase liquid chromatographic method for the quantitative determination of levofloxacin as well as its related substances determination in bulk samples, pharmaceutical dosage forms in the presence of degradation products and its process related impurities. Forced degradation studies were performed on bulk sample of levofloxacin as per ICH prescribed stress conditions using acid, base, oxidative, water hydrolysis, thermal stress and photolytic degradation to show the stability indicating power of the method. Significant degradation was observed during oxidative stress and the degradation product formed was identified by LCMS/MS, slight degradation in acidic stress and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies and the impurity spiked solution. Good resolution between the peaks corresponds to process related impurities and degradation products from the analyte were achieved on ACE C18 column using the mobile phase consists a mixture of 0.5% (v/v) triethyl amine in sodium dihydrogen orthophosphate dihydrate (25 mM; pH 6.0) and methanol using a simple linear gradient. The detection was carried out at 294 nm. The limit of detection and the limit of quantitation for the levofloxacin and its process related impurities were established. The stressed test solutions were assayed against the qualified working standard of levofloxacin and the mass balance in each case was in between 99.4 and 99.8% indicating that the developed LC method was stability indicating. Validation of the developed LC method was carried out as per ICH requirements. The developed LC method was found to be suitable to check the quality of bulk samples of levofloxacin at the time of batch release and also during its stability studies (long term and accelerated stability).

THE CHALLENGE OF PD PATIENTS: GLUCOSE AND GLUCOSE DEGRADATION PRODUCTS IN PD SOLUTION

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Yong-Lim Kim

2012-06-01

Full Text Available The main osmotic agent found in the peritoneal dialysis (PD solution is glucose. It has been of a wide use for great crystalloid osmotic power at a low concentration, simple metabolism, and excellent safety. On the other hand, anywhere between 60 to 80% of the glucose in the PD solution is absorbed - a 100 to 300 mg of daily glucose absorption. Once into the systemic circulation, glucose can be a cause for metabolic complications including obesity. Indeed, the diabetiform change observed in the peritoneal membrane in the long-term PD patients is believed attributable to the high-concentration glucose in the PD solution. The glucose absorbed from peritoneal cavity raises the risk of ‘glucose toxicity’, leading to insulin resistance and beta cell failure. Clinical similarity can be found in postprandial hyperglycemia, which is known to be associated with oxidative stress, endothelial dysfunction, NF-κb, and inflammation, affecting myocardial blood flow. Moreover, it is a proven independent risk factor of coronary artery disease in patients with type 2 diabetes, particularly of female gender. Though speculative yet, glucose toxicity might explain a higher mortality of PD patients after the first year compared with those on hemodialysis (more so in female, advanced-age patients with diabetes. Also included in the picture are glucose degradation products (GDPs generated along the course of heat sterilization or storage of the PD solution. They have been shown to induce apoptosis of peritoneal mesothelial cells, renal tubular epithelial cells, and endothelial cells, while spurring production of TGF-β and VEGF and facilitating epithelial mesenchymal transition. GDPs provide a stronger reactivity than glucose in the formation of AGEs, a known cause for microvascular complications and arteriosclerosis. Unfortunately, clinical studies using a low-GDP PD solution have provided mixed results on the residual renal function, peritonitis, peritoneal

Toxicity and physical properties of atrazine and its degradation products: A literature survey

Energy Technology Data Exchange (ETDEWEB)

Pugh, K.C.

1994-10-01

The Tennessee Valley Authority`s Environmental Research Center has been developing a means of detoxifying atrazine waste waters using TiO{sub 2} photocatalysis. The toxicity and physical properties of atrazine and its degradation products will probably be required information in obtaining permits from the United States Environmental Protection Agency for the demonstration of any photocatalytic treatment of atrazine waste waters. The following report is a literature survey of the toxicological and physical properties of atrazine and its degradation products.

Defect production in Ar irradiated graphene membranes under different initial applied strains

Energy Technology Data Exchange (ETDEWEB)

Martinez-Asencio, J., E-mail: jesusmartinez@ua.es [Dept. Física Aplicada, Facultad de Ciencias, Fase II, Universidad de Alicante, Alicante E-036090 (Spain); Ruestes, C.J.; Bringa, E. [CONICET and Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza 5500 (Argentina); Caturla, M.J. [Dept. Física Aplicada, Facultad de Ciencias, Fase II, Universidad de Alicante, Alicante E-036090 (Spain)

2017-02-15

Highlights: • Defects in graphene membranes are formed due to 140 eV Ar ions irradiation using MD. • Different initial strains are applied, which influence the type and number of defects. • Mono-vacancies, di-vacancies and tri-vacancies production behaves linearly with dose. • The total number of defects under compression is slightly higher than under tension. - Abstract: Irradiation with low energy Ar ions of graphene membranes gives rise to changes in the mechanical properties of this material. These changes have been associated to the production of defects, mostly isolated vacancies. However, the initial state of the graphene membrane can also affect its mechanical response. Using molecular dynamics simulations we have studied defect production in graphene membranes irradiated with 140 eV Ar ions up to a dose of 0.075 × 10{sup 14} ions/cm{sup 2} and different initial strains, from −0.25% (compressive strain) to 0.25% (tensile strain). For all strains, the number of defects increases linearly with dose with a defect production of about 80% (80 defects every 100 ions). Defects are mostly single vacancies and di-vacancies, although some higher order clusters are also observed. Two different types of di-vacancies have been identified, the most common one being two vacancies at first nearest neighbours distance. Differences in the total number of defects with the applied strain are observed which is related to the production of a higher number of di-vacancies under compressive strain compared to tensile strain. We attribute this effect to the larger out-of-plane deformations of compressed samples that could favor the production of defects in closer proximity to others.

Time extrapolation of radiolytic degradation product kinetics: the case of polyurethane; Extrapolation dans le temps des cinetiques de production des produits de degradation radiolytique: application a un polyurethane

Energy Technology Data Exchange (ETDEWEB)

Dannoux, A

2007-02-15

The prediction of the environmental impact of organic materials in nuclear waste geological storage needs knowledge of radiolytic degradation mechanisms and kinetics in aerobic and anaerobic conditions. In this framework, the effect of high doses (> MGy) and the variation of dose rate have to be considered. The material studied is a polyurethane composed of polyether soft segment and aromatic hard segments. Mechanisms were built on the analysis of material submitted to irradiations of simulation (high energy electrons and gamma radiation) by FTIR spectroscopy and gaseous and liquid degradation products by gas mass spectrometry and size exclusion chromatography. The electron paramagnetic resonance study of radical process and the determination of oxygen consumption and gas formation radiolytic yields allowed us to acquire kinetic data and to estimate dose rate and high doses effects. The polyurethane radio-oxidation mainly concerns soft segments and induced cross-linkings and production by scissions of oxidised compounds (esters, alcohols, carboxylic acids). The kinetic of radical termination is rapid and the dose rate effect is limited. After 10 MGy, branching and scission reactions are in equilibrium and low molecular weight products accumulate. At last, the degradation products release in water is influenced by the oxidation rate and the temperature. After 10 MGy, the soluble fraction is stabilised at 25%. The water soluble products identified by electro-spray ionisation mass spectrometry (alcohols, aldehydes, carboxylic acids) potentially formed complexes with radionuclides. (author)

Environmental, biochemical and genetic drivers of DMSP degradation and DMS production in the Sargasso Sea.

Science.gov (United States)

Levine, Naomi Marcil; Varaljay, Vanessa A; Toole, Dierdre A; Dacey, John W H; Doney, Scott C; Moran, Mary Ann

2012-05-01

Dimethylsulfide (DMS) is a climatically relevant trace gas produced and cycled by the surface ocean food web. Mechanisms driving intraannual variability in DMS production and dimethylsulfoniopropionate (DMSP) degradation in open-ocean, oligotrophic regions were investigated during a 10-month time-series at the Bermuda Atlantic Time-series Study site in the Sargasso Sea. Abundance and transcription of bacterial DMSP degradation genes, DMSP lyase enzyme activity, and DMS and DMSP concentrations, consumption rates and production rates were quantified over time and depth. This interdisciplinary data set was used to test current hypotheses of the role of light and carbon supply in regulating upper-ocean sulfur cycling. Findings supported UV-A-dependent phytoplankton DMS production. Bacterial DMSP degraders may also contribute significantly to DMS production when temperatures are elevated and UV-A dose is moderate, but may favour DMSP demethylation under low UV-A doses. Three groups of bacterial DMSP degraders with distinct intraannual variability were identified and niche differentiation was indicated. The combination of genetic and biochemical data suggest a modified 'bacterial switch' hypothesis where the prevalence of different bacterial DMSP degradation pathways is regulated by a complex set of factors including carbon supply, temperature and UV-A dose. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Solar fuel production at high temperatures using ceria as a dense membrane

International Nuclear Information System (INIS)

Zhu, Liya; Lu, Youjun; Shen, Shaohua

2016-01-01

In this paper, ceria was proposed as a candidate material of membrane reactor for solar fuel production. A thermodynamic model of the membrane reactor system based on ceria with heat recovery was established and solar-to-fuel efficiency of both inert gas-assisted and pump-assisted CO_2 splitting was calculated under a broad range of conditions. For system using inert gas, gas heat recovery is the determining factor for energy conversion efficiency. The energy efficiency is calculated to be >10% at 1800 K when the oxygen pressure at the inlet of reduction zone is lower than 10"−"6MPa. Increase of total pressure of the oxidation zone could improve the energy efficiency due to decrease of gas heat loss. Significant promotion in efficiency could be expected when a pump is applied to avoid using inert gas. Solar-to-fuel efficiency could be above 40% assuming good heat recovery. For the membrane reactor with a pump applied to maintain a vacuum atmosphere of the reduction zone, a simplified steady state model was put forward to predict the converting process and estimate the productivity. The diffusion rate of oxygen ions in the membrane is fast enough for conversion of considerable amount of CO_2 in the reactor with a limited geometry. - Highlights: • Ceria membrane reactor was proposed for solar fuel production. • A thermodynamic model of the ceria membrane reactor system was established. • Inert gas-assisted and pump-assisted systems were evaluated. • High efficiency >40% could be expected when using a pump instead of inert gas. • A steady state model concerning oxygen diffusion rate was established.

Determination of trace amounts of chemical warfare agent degradation products in decontamination solutions with NMR spectroscopy.

Science.gov (United States)

Koskela, Harri; Rapinoja, Marja-Leena; Kuitunen, Marja-Leena; Vanninen, Paula

2007-12-01

Decontamination solutions are used for an efficient detoxification of chemical warfare agents (CWAs). As these solutions can be composed of strong alkaline chemicals with hydrolyzing and oxidizing properties, the analysis of CWA degradation products in trace levels from these solutions imposes a challenge for any analytical technique. Here, we present results of application of nuclear magnetic resonance spectroscopy for analysis of trace amounts of CWA degradation products in several untreated decontamination solutions. Degradation products of the nerve agents sarin, soman, and VX were selectively monitored with substantially reduced interference of background signals by 1D 1H-31P heteronuclear single quantum coherence (HSQC) spectrometry. The detection limit of the chemicals was at the low part-per-million level (2-10 microg/mL) in all studied solutions. In addition, the concentration of the degradation products was obtained with sufficient confidence with external standards.

Degradable polyphosphazene/poly(alpha-hydroxyester) blends: degradation studies.

Science.gov (United States)

Ambrosio, Archel M A; Allcock, Harry R; Katti, Dhirendra S; Laurencin, Cato T

2002-04-01

Biomaterials based on the polymers of lactic acid and glycolic acid and their copolymers are used or studied extensively as implantable devices for drug delivery, tissue engineering and other biomedical applications. Although these polymers have shown good biocompatibility, concerns have been raised regarding their acidic degradation products, which have important implications for long-term implantable systems. Therefore, we have designed a novel biodegradable polyphosphazene/poly(alpha-hydroxyester) blend whose degradation products are less acidic than those of the poly(alpha-hydroxyester) alone. In this study, the degradation characteristics of a blend of poly(lactide-co-glycolide) (50:50 PLAGA) and poly[(50% ethyl glycinato)(50% p-methylphenoxy) phosphazene] (PPHOS-EG50) were qualitatively and quantitatively determined with comparisons made to the parent polymers. Circular matrices (14mm diameter) of the PLAGA, PPHOS-EG50 and PLAGA-PPHOS-EG50 blend were degraded in non-buffered solutions (pH 7.4). The degraded polymers were characterized for percentage mass loss and molecular weight and the degradation medium was characterized for acid released in non-buffered solutions. The amounts of neutralizing base necessary to bring about neutral pH were measured for each polymer or polymer blend during degradation. The poly(phosphazene)/poly(lactide-co-glycolide) blend required significantly less neutralizing base in order to bring about neutral solution pH during the degradation period studied. The results indicated that the blend degraded at a rate intermediate to that of the parent polymers and that the degradation products of the polyphosphazene neutralized the acidic degradation products of PLAGA. Thus, results from these in vitro degradation studies suggest that the PLAGA-PPHOS-EG50 blend may provide a viable improvement to biomaterials based on acid-releasing organic polymers.

Characterization of stress degradation products of benazepril by using sophisticated hyphenated techniques.

Science.gov (United States)

Narayanam, Mallikarjun; Sahu, Archana; Singh, Saranjit

2013-01-04

Benazepril, an anti-hypertensive drug, was subjected to forced degradation studies. The drug was unstable under hydrolytic conditions, yielding benazeprilat, which is a known major degradation product (DP) and an active metabolite. It also underwent photochemical degradation in acid and neutral pH conditions, resulting in multiple minor DPs. The products were separated on a reversed phase (C18) column in a gradient mode, and subjected to LC-MS and LC-NMR studies. Initially, comprehensive mass fragmentation pathway of the drug was established through support of high resolution mass spectrometric (HR-MS) and multi stage tandem mass spectrometric (MS(n)) data. The DPs were also subjected to LC-MS/TOF studies to obtain their accurate masses. Along with, on-line H/D exchange data were obtained to ascertain the number of exchangeable hydrogens in each molecule. LC-(1)H NMR and LC-2DNMR data were additionally acquired in a fraction loop mode. The whole information was successfully employed for the characterization of all the DPs. A complete degradation pathway of the drug was also established. Copyright © 2012 Elsevier B.V. All rights reserved.

Reliability modeling of degradation of products with multiple performance characteristics based on gamma processes

International Nuclear Information System (INIS)

Pan Zhengqiang; Balakrishnan, Narayanaswamy

2011-01-01

Many highly reliable products usually have complex structure, with their reliability being evaluated by two or more performance characteristics. In certain physical situations, the degradation of these performance characteristics would be always positive and strictly increasing. In such a case, the gamma process is usually considered as a degradation process due to its independent and non-negative increments properties. In this paper, we suppose that a product has two dependent performance characteristics and that their degradation can be modeled by gamma processes. For such a bivariate degradation involving two performance characteristics, we propose to use a bivariate Birnbaum-Saunders distribution and its marginal distributions to approximate the reliability function. Inferential method for the corresponding model parameters is then developed. Finally, for an illustration of the proposed model and method, a numerical example about fatigue cracks is discussed and some computational results are presented.

A positive feedback-based gene circuit to increase the production of a membrane protein

Directory of Open Access Journals (Sweden)

Gennis Robert B

2010-05-01

Full Text Available Abstract Background Membrane proteins are an important class of proteins, playing a key role in many biological processes, and are a promising target in pharmaceutical development. However, membrane proteins are often difficult to produce in large quantities for the purpose of crystallographic or biochemical analyses. Results In this paper, we demonstrate that synthetic gene circuits designed specifically to overexpress certain genes can be applied to manipulate the expression kinetics of a model membrane protein, cytochrome bd quinol oxidase in E. coli, resulting in increased expression rates. The synthetic circuit involved is an engineered, autoinducer-independent variant of the lux operon activator LuxR from V. fischeri in an autoregulatory, positive feedback configuration. Conclusions Our proof-of-concept experiments indicate a statistically significant increase in the rate of production of the bd oxidase membrane protein. Synthetic gene networks provide a feasible solution for the problem of membrane protein production.

Mixed hydrocarbon/fluoropolymer membrane/ionomer MEAs for durability studies

Energy Technology Data Exchange (ETDEWEB)

Li, Bo [Los Alamos National Laboratory; Kim, Yu Seung [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory; Borup, Rodney L [Los Alamos National Laboratory; Wilson, Mahlon S [Los Alamos National Laboratory; Welch, Cynthia [Los Alamos National Laboratory; Fenton, James [FLORIDA SOLAR ENERGY CENTER

2010-01-01

The durability of polymer electrolyte membrane (PEM) fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. Commercial viability depends on improving the durability of the fuel cell components to increase the system reliability. The aim of this work is to separate ionomer degradation from membrane degradation via mixed membrane/ionomer MEA experiments. The challenges of mixed MEA fabrication due to the incompatibility of the membrane and the electrode are addressed. OCV accelerated testing experiment (AST) were performed. Development of in situ diagnostics and unique experiments to characterize the performance and properties of the ionomer in the electrode as a function of time is reported. These measurements, along with extensive ex situ and post-mortem characterization, can delineate the degradation mechanisms in order to develop more durable fuel cells and fuel cell components.

LC-MS characterization of valsartan degradation products and comparison with LC-PDA

Directory of Open Access Journals (Sweden)

Sumaia Araújo Pires

2015-12-01

Full Text Available abstract Valsartan was submitted to forced degradation under acid hydrolysis condition as prescribed by the ICH. Degraded sample aliquots were separated via HPLC using a Hypersil ODS (C18 column (250 x 4.6 mm i.d., 5 µm. Either photodiode array (PDA detection or mass spectrometry (MS full scan monitoring of HPLC runs were used. HPLC-PDA failed to indicate Valsartan degradation under forced acid degradation, showing an insignificant peak area variation and that Valsartan apparently remained pure. HPLC-MS using electrospray ionization (ESI and total ionic current (TIC monitoring did not reveal any peak variation either, but inspection of the ESI mass spectra showed the appearance of m/z 306 and m/z 352 ions for the same retention time as that of Valsartan (m/z 436. These ions were identified as being protonated molecules of two co-eluting degradation products formed by hydrolysis. These assignments were confirmed by ESI-MS/MS with direct infusion of the degraded samples. The results showed that the use of selective HPLC-MS is essential for monitoring Valsartan degradation. Efficient HPLC separation coupled to selective and structural diagnostic MS monitoring seems therefore mandatory for comprehensive drug degradation studies, particularly for new drugs and formulations, and for method development.

System design study of a membrane reforming hydrogen production plant using a small sized sodium cooled reactor

International Nuclear Information System (INIS)

Chikazawa, Y.; Konomura, M.; Hori, T.; Sato, H.; Uchida, S.

2004-01-01

In this study, a membrane reforming hydrogen production plant using a small sized sodium cooled reactor was designed as one of promising concepts. In the membrane reformer, methane and steam are reformed into carbon dioxide and hydrogen with sodium heat at a temperature 500 deg-C. In the equilibrium condition, steam reforming proceeds with catalyst at a temperature more than 800 deg-C. Using membrane reformers, the steam reforming temperature can be decreased from 800 to 500 deg-C because the hydrogen separation membrane removes hydrogen selectively from catalyst area and the partial pressure of hydrogen is kept much lower than equilibrium condition. In this study, a hydrogen and electric co-production plant has been designed. The reactor thermal output is 375 MW and 25% of the thermal output is used for hydrogen production (70000 Nm 3 /h). The hydrogen production cost is estimated to 21 yen/Nm 3 but it is still higher than the economical goal (17 yen/Nm 3 ). The major reason of the high cost comes from the large size of hydrogen separation reformers because of the limit of hydrogen separation efficiency of palladium membrane. A new highly efficient hydrogen separation membrane is needed to reduce the cost of hydrogen production using membrane reformers. There is possibility of multi-tube failure in the membrane reformers. In future study, a design of measures against tube failure and elemental experiments of reaction between sodium and reforming gas will be needed. (authors)

Synthesis of a catalytic reactor membrane for synthesis gas production; Elaboration d'une membrane de reacteur catalytique pour la production de gaz de synthese

Energy Technology Data Exchange (ETDEWEB)

Juste, E.; Julian, A.; Chartier, T. [Limoges Univ., Lab. Science des Procedes Ceramiques et de Traitements de Surface (SPCTS, UMR 6638 CNRS), 87 (France); Juste, E.; Julian, A.; Del Gallo, P.; Richet, N. [Centre de Recherche Claude-Delorme, Air Liquide, 78 - Jouy en Josas (France)

2007-07-01

The conversion of natural gas to synthesis gas (mixture of H{sub 2} and CO) is a main challenge for the hydrogen and clean fuels production. Mixed (ionic O{sup 2-} and electronic) conducing ceramics membrane reactors seem particularly promising. The design considered for the membrane is a tri-layer system integrating a reforming catalyst and a dense membrane laying on a porous support. Among the materials considered for the dense membrane, perovskites La{sub 1-x}Sr{sub x}Fe{sub 1-y}Ga{sub y}O{sub 3-{delta}} seem to be interesting for their performances and stability. The oxygen flux through the membrane is measured in terms of temperature under different oxygen partial pressure gradients. In the industrial experimental conditions, the membrane is submitted to a strong oxygen (air/methane) partial pressure gradient of about 900 C which induces mechanical stresses, on account of the material expansion difference, in terms of p{sub O2}. In this framework, the evolutions of the performances and of the expansion coefficient have been followed in terms of the substitutions rates in La{sub (1-x)}Sr{sub x}Fe{sub (1-y)}Ga{sub y}O{sub 3-{delta}} with x{<=}0.5 and y{<=}0.5. (O.M.)

Zeolite Membrane Reactor for Water Gas Shift Reaction for Hydrogen Production

Energy Technology Data Exchange (ETDEWEB)

Lin, Jerry Y.S. [Arizona State Univ., Mesa, AZ (United States)

2013-01-29

Gasification of biomass or heavy feedstock to produce hydrogen fuel gas using current technology is costly and energy-intensive. The technology includes water gas shift reaction in two or more reactor stages with inter-cooling to maximize conversion for a given catalyst volume. This project is focused on developing a membrane reactor for efficient conversion of water gas shift reaction to produce a hydrogen stream as a fuel and a carbon dioxide stream suitable for sequestration. The project was focused on synthesizing stable, hydrogen perm-selective MFI zeolite membranes for high temperature hydrogen separation; fabricating tubular MFI zeolite membrane reactor and stable water gas shift catalyst for membrane reactor applications, and identifying experimental conditions for water gas shift reaction in the zeolite membrane reactor that will produce a high purity hydrogen stream. The project has improved understanding of zeolite membrane synthesis, high temperature gas diffusion and separation mechanisms for zeolite membranes, synthesis and properties of sulfur resistant catalysts, fabrication and structure optimization of membrane supports, and fundamentals of coupling reaction with separation in zeolite membrane reactor for water gas shift reaction. Through the fundamental study, the research teams have developed MFI zeolite membranes with good perm-selectivity for hydrogen over carbon dioxide, carbon monoxide and water vapor, and high stability for operation in syngas mixture containing 500 part per million hydrogen sulfide at high temperatures around 500°C. The research teams also developed a sulfur resistant catalyst for water gas shift reaction. Modeling and experimental studies on the zeolite membrane reactor for water gas shift reaction have demonstrated the effective use of the zeolite membrane reactor for production of high purity hydrogen stream.

Methanogenic degradation of toilet-paper cellulose upon sewage treatment in an anaerobic membrane bioreactor at room temperature.

Science.gov (United States)

Chen, Rong; Nie, Yulun; Kato, Hiroyuki; Wu, Jiang; Utashiro, Tetsuya; Lu, Jianbo; Yue, Shangchao; Jiang, Hongyu; Zhang, Lu; Li, Yu-You

2017-03-01

Toilet-paper cellulose with rich but refractory carbon sources, are the main insoluble COD fractions in sewage. An anaerobic membrane bioreactor (AnMBR) was configured for sewage treatment at room temperature and its performance on methanogenic degradation of toilet paper was highlighted. The results showed, high organic removal (95%), high methane conversion (90%) and low sludge yield (0.08gVSS/gCOD) were achieved in the AnMBR. Toilet-paper cellulose was fully biodegraded without accumulation in the mixed liquor and membrane cake layer. Bioconversion efficiency of toilet paper approached 100% under a high organic loading rate (OLR) of 2.02gCOD/L/d and it could provide around 26% of total methane generation at most of OLRs. Long sludge retention time and co-digestion of insoluble/soluble COD fractions achieving mutualism of functional microorganisms, contributed to biodegradation of toilet-paper cellulose. Therefore the AnMBR successfully implemented simultaneously methanogenic bioconversion of toilet-paper cellulose and soluble COD in sewage at room temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimating grass and grass silage degradation characteristics by in situ and in vitro gas production methods

Directory of Open Access Journals (Sweden)

Danijel Karolyi

2010-01-01

Full Text Available Fermentation characteristics of grass and grass silage at different maturities were studied using in situ and in vitro gas production methods. In situ data determined difference between grass and silage. Degradable fraction decreased as grass matured while the undegradable fraction increased. Rate of degradation (kd was slower for silage than fresh grass. Gas production method (GP data showed that fermentation of degradable fraction was different between stage of maturity in both grass and silage. Other data did not show any difference with the exception for the rate of GP of soluble and undegradable fraction. The in situ degradation characteristics were estimated from GP characteristics. The degradable and undegradable fractions could be estimated by multiple relationships. Using the three-phases model for gas production kd and fermentable organic matter could be estimated from the same parameters. The only in situ parameter that could not be estimated with GP parameters was the soluble fraction. The GP method and the three phases model provided to be an alternative to the in situ method for animal feed evaluations.

Tailoring Escherichia coli for the L-rhamnose PBAD promoter-based production of membrane and secretory proteins

NARCIS (Netherlands)

Hjelm, Anna; Karyolaimos, Alexandros; Zhang, Zhe; Rujas, Edurne; Vikström, David; Slotboom, Dirk Jan; de Gier, Jan-Willem

Membrane and secretory protein production in Escherichia coli requires precisely controlled production rates to avoid the deleterious saturation of their biogenesis pathways. Based on this requirement, the E. coli L-rhamnose PBAD promoter (PrhaBAD) is often used for membrane and secretory protein

In vitro degradation of the 32kDa PS II reaction centre protein

International Nuclear Information System (INIS)

Eckenswiller, L.C.; Greenberg, B.M.

1989-01-01

The 32kDa thylakoid membrane protein is an integral component of the PS II reaction centre. The protein, although stable in the dark, undergoes light dependent turnover. Light from the UV, visible and far-red spectral regions induce 32kDa protein degradation. To better understand 32kDa protein metabolism, an in vitro degradation system is being developed. It consists of isolated thylakoid membranes than contain radiolabelled protein. The 32kDa protein is actively and specifically degraded when the thylakoid preparation is exposed to UV or visible radiation. The protein is stable in the dark. The herbicides (atrazine and DCMU) inhibit degradation in the in vitro system as they do in vivo. Additionally, several methods of isolating thylakoids are being compared to optimize the 32kDa protein degradation reaction. The preparations will be evaluated based on their ability to permit light dependent degradation of the 32kDa protein without affecting the other membrane components

Full Product Pattern Recognition in β-Carotene Thermal Degradation through Ionization Enhancement

Energy Technology Data Exchange (ETDEWEB)

Xiao, Xiaoyin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Miller, Lance Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bernstein, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hochrein, James M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-07-01

The full product pattern including both volatile and nonvolatile compounds was presented for the first time for β-Carotene thermal degradation at variable temperatures up to 600°C. Solvent-enhanced ionization was used to confirm and distinguish between the dissociation mechanisms that lead to even and odd number mass products.

Photochemical hydrogen production through solar radiation by means of the membrane principle

International Nuclear Information System (INIS)

Broda, E.

1976-01-01

This report was written by Enelbert Broda from the University of Vienna for the UNESCO-Solar-Energy-Symposium in Geneva in 1976. Nuclear experts are considering a 'hydrogen economy' where H 2 serves as a fuel to make electricity, as a chemical reactant, as a metallurgical reductant and as a source of food. Now H 2 could also be made by photolysis of water. Theoretically, a quantum of green light carries enough energy for the reaction H 2 0 = H 2 + 0.5 0 2 . With long-wave light, photolysis could be achieved by combination of 2 quanta. Yet attempts to photolyze water, in presence of sensitizers (photocatalysts), have failed. In the last analysis, this is due to re-combination of the primary, highly reactive, products of the photochemical reaction. A solution of the problem is to be found by the spatial separation of the primary production by development of suitable membranes where these products, and therefore also the stable gases H 2 and 0 2 , come out on opposite sides. The feasibility of this 'membrane principle' has been shown in Nature for 3 giga-years. Using membranes, all photosynthetic cells (photosynthetic bacteria and plants) succeed in the photo-production of a reductant (in many cases at least ferredoxin in the reduced form) with a redox potential equal to that of H 2 in neutral solution (-0.4 v). The reductant can, but need not, be used by the cells for C0 2 assimilation. In man-made technology, the reducing power would be diverted as H 2 . Here it is not suggested to use or copy living cells. Rather their operation is to be studied so that technically useful membranes for water photolysis can be constructed abiotically. The scientific and practical aspects of large-scale photolytic H 2 production are discussed. (author)

Evaluation of anaerobic degradation, biogas and digestate production of cereal silages using nylon-bags.

Science.gov (United States)

Negri, Marco; Bacenetti, Jacopo; Fiala, Marco; Bocchi, Stefano

2016-06-01

In this study, the degradation efficiency and the biogas and digestate production during anaerobic digestion were evaluated for the cereal silages most used to feed biogas plants. To this purpose, silages of: maize from the whole plant, maize from the ear, triticale and wheat were digested, inside of nylon bags, in laboratory scale digesters, for 75days. Overall, the test involved 288 nylon bags. After 75days of digestion, the maize ear silage shows the highest degradation efficiency (about 98%) while wheat silage the lowest (about 83%). The biogas production ranges from 438 to 852Nm(3)/t of dry matter for wheat and ear maize silage, respectively. For all the cereal silages, the degradation as well as the biogas production are faster at the beginning of the digestion time. Digestate mass, expressed as percentage of the fresh matter, ranges from 38% to 84% for wheat and maize ear silage, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Durability Improvements Through Degradation Mechanism Studies

Energy Technology Data Exchange (ETDEWEB)

Borup, Rodney L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mukundan, Rangachary [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Spernjak, Dusan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baker, Andrew M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lujan, Roger W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Langlois, David Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ahluwalia, Rajesh [Argonne National Lab. (ANL), Argonne, IL (United States); Papadia, D. D. [Argonne National Lab. (ANL), Argonne, IL (United States); Weber, Adam Z. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kusoglu, Ahmet [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shi, Shouwnen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); More, K. L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Grot, Steve [Ion Power, New Castle, DE (United States)

2015-08-03

The durability of polymer electrolyte membrane (PEM) fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. By investigating cell component degradation modes and defining the fundamental degradation mechanisms of components and component interactions, new materials can be designed to improve durability. To achieve a deeper understanding of PEM fuel cell durability and component degradation mechanisms, we utilize a multi-institutional and multi-disciplinary team with significant experience investigating these phenomena.

Hydrogen production by water dissociation using ceramic membranes - annual report for FY 2010.

Energy Technology Data Exchange (ETDEWEB)

Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J. (Energy Systems)

2011-03-14

The objective of this project is to develop dense ceramic membranes that can produce hydrogen via coal/coal gas-assisted water dissociation without using an external power supply or circuitry. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen using OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

Nutrient utilization and oxygen production by Chlorella Vulgaris in a hybrid membrane bioreactor and algal membrane photobioreactor system

KAUST Repository

Najm, Yasmeen Hani Kamal; Jeong, Sanghyun; Leiknes, TorOve

2017-01-01

This work studied oxygen production and nutrient utilization by Chlorella Vulgaris at different organic/inorganic carbon (OC/IC) and ammonium/nitrate (NH4+-N/NO3--N) ratios to design a hybrid aerobic membrane bioreactor (MBR) and membrane photobioreactor (MPBR) system. Specific oxygen production by C. vulgaris was enough to support the MBR if high growth is accomplished. Nearly 100% removal (or utilization) of PO43--P and IC was achieved under all conditions tested. Optimal growth was achieved at mixotrophic carbon conditions (0.353 d-1) and the highest NH4+-N concentration (0.357 d-1), with preferable NH4+-N utilization rather than NO3--N. The results indicate the potential of alternative process designs to treat domestic wastewater by coupling the hybrid MBR - MPBR systems.

Nutrient utilization and oxygen production by Chlorella Vulgaris in a hybrid membrane bioreactor and algal membrane photobioreactor system

KAUST Repository

Najm, Yasmeen Hani Kamal

2017-02-17

This work studied oxygen production and nutrient utilization by Chlorella Vulgaris at different organic/inorganic carbon (OC/IC) and ammonium/nitrate (NH4+-N/NO3--N) ratios to design a hybrid aerobic membrane bioreactor (MBR) and membrane photobioreactor (MPBR) system. Specific oxygen production by C. vulgaris was enough to support the MBR if high growth is accomplished. Nearly 100% removal (or utilization) of PO43--P and IC was achieved under all conditions tested. Optimal growth was achieved at mixotrophic carbon conditions (0.353 d-1) and the highest NH4+-N concentration (0.357 d-1), with preferable NH4+-N utilization rather than NO3--N. The results indicate the potential of alternative process designs to treat domestic wastewater by coupling the hybrid MBR - MPBR systems.

Analysis of deltamethrin's degradation products by irradiation

International Nuclear Information System (INIS)

Wu Ling; Huang Min; Chen Chun; Lei Qing; Du Xiaoying; Xie Yan; Wang Yan; Gao Peng; He Jiang

2011-01-01

Deltamethrin were dissolved in ethanol and water; acetone and water; dimethylsulfoxide and water, irradiating these liquors by 60 Co-γ under the dose of 5∼50 kGy. The irradiation system were analyzed by GC/MS, result shows: there were some differences under different irradiation doses; the main degradation products are: α-cyano-3-phenoxy benzyl alcohol, 3-Phenoxybenzaldehyde, 3-Phenoxybenzacetonitrile and bromomethane. (authors)

Identification of soil bacteria able to degrade phenanthrene bound to a hydrophobic sorbent in situ

Energy Technology Data Exchange (ETDEWEB)

Regonne, Raïssa Kom [CEA, DSV/iRTSV, Chimie et Biologie des Métaux, 38054, Grenoble cedex 9 (France); Univ. Grenoble Alpes and CNRS, UMR 5249, 38042, Grenoble (France); Laboratoire de Substances Actives et Pollution, ENSAI, Université de Ngaoundéré, BP 455, Ngaoundéré (Cameroon); Martin, Florence [CEA, DSV/iRTSV, Chimie et Biologie des Métaux, 38054, Grenoble cedex 9 (France); Univ. Grenoble Alpes and CNRS, UMR 5249, 38042, Grenoble (France); Mbawala, Augustin [Laboratoire de Microbiologie, ENSAI, Université de Ngaoundéré, BP 455, Ngaoundéré (Cameroon); Ngassoum, Martin Benoît [Laboratoire de Substances Actives et Pollution, ENSAI, Université de Ngaoundéré, BP 455, Ngaoundéré (Cameroon); Jouanneau, Yves [CEA, DSV/iRTSV, Chimie et Biologie des Métaux, 38054, Grenoble cedex 9 (France); Univ. Grenoble Alpes and CNRS, UMR 5249, 38042, Grenoble (France)

2013-09-15

Efficient bioremediation of PAH-contaminated sites is limited by the hydrophobic character and poor bioavailability of pollutants. In this study, stable isotope probing (SIP) was implemented to track bacteria that can degrade PAHs adsorbed on hydrophobic sorbents. Temperate and tropical soils were incubated with {sup 13}C-labeled phenanthrene, supplied by spiking or coated onto membranes. Phenanthrene mineralization was faster in microcosms with PAH-coated membranes than in microcosms containing spiked soil. Upon incubation with temperate soil, phenanthrene degraders found in the biofilms that formed on coated membranes were mainly identified as Sphingomonadaceae and Actinobacteria. In the tropical soil, uncultured Rhodocyclaceae dominated degraders bound to membranes. Accordingly, ring-hydroxylating dioxygenase sequences recovered from this soil matched PAH-specific dioxygenase genes recently found in Rhodocyclaceae. Hence, our SIP approach allowed the detection of novel degraders, mostly uncultured, which differ from those detected after soil spiking, but might play a key role in the bioremediation of PAH-polluted soils. -- Highlights: •Soil bacteria with the ability to degrade sorbent-bound PAHs were investigated. •In soil, membrane-bound phenanthrene was readily mineralized. •PAH degraders found in biofilms were different in temperate and tropical soils. •Uncultured Rhodocyclaceae were dominant phenanthrene degraders in the tropical soil. •PAH-specific ring-hydroxylating dioxygenase sequences were identified in soil DNA. -- Bacteria able to degrade PAHs bound to a hydrophobic sorbent were mainly identified as uncultured Rhodocyclaceae and Sphingomonadaceae in polluted soils from tropical and temperate area, respectively.

Identification of soil bacteria able to degrade phenanthrene bound to a hydrophobic sorbent in situ

International Nuclear Information System (INIS)

Regonne, Raïssa Kom; Martin, Florence; Mbawala, Augustin; Ngassoum, Martin Benoît; Jouanneau, Yves

2013-01-01

Efficient bioremediation of PAH-contaminated sites is limited by the hydrophobic character and poor bioavailability of pollutants. In this study, stable isotope probing (SIP) was implemented to track bacteria that can degrade PAHs adsorbed on hydrophobic sorbents. Temperate and tropical soils were incubated with 13 C-labeled phenanthrene, supplied by spiking or coated onto membranes. Phenanthrene mineralization was faster in microcosms with PAH-coated membranes than in microcosms containing spiked soil. Upon incubation with temperate soil, phenanthrene degraders found in the biofilms that formed on coated membranes were mainly identified as Sphingomonadaceae and Actinobacteria. In the tropical soil, uncultured Rhodocyclaceae dominated degraders bound to membranes. Accordingly, ring-hydroxylating dioxygenase sequences recovered from this soil matched PAH-specific dioxygenase genes recently found in Rhodocyclaceae. Hence, our SIP approach allowed the detection of novel degraders, mostly uncultured, which differ from those detected after soil spiking, but might play a key role in the bioremediation of PAH-polluted soils. -- Highlights: •Soil bacteria with the ability to degrade sorbent-bound PAHs were investigated. •In soil, membrane-bound phenanthrene was readily mineralized. •PAH degraders found in biofilms were different in temperate and tropical soils. •Uncultured Rhodocyclaceae were dominant phenanthrene degraders in the tropical soil. •PAH-specific ring-hydroxylating dioxygenase sequences were identified in soil DNA. -- Bacteria able to degrade PAHs bound to a hydrophobic sorbent were mainly identified as uncultured Rhodocyclaceae and Sphingomonadaceae in polluted soils from tropical and temperate area, respectively

How early studies on secreted and membrane protein quality control gave rise to the ER associated degradation (ERAD) pathway: the early history of ERAD.

Science.gov (United States)

Needham, Patrick G; Brodsky, Jeffrey L

2013-11-01

All newly synthesized proteins are subject to quality control check-points, which prevent aberrant polypeptides from harming the cell. For proteins that ultimately reside in the cytoplasm, components that also reside in the cytoplasm were known for many years to mediate quality control. Early biochemical and genetic data indicated that misfolded proteins were selected by molecular chaperones and then targeted to the proteasome (in eukaryotes) or to proteasome-like particles (in bacteria) for degradation. What was less clear was how secreted and integral membrane proteins, which in eukaryotes enter the endoplasmic reticulum (ER), were subject to quality control decisions. In this review, we highlight early studies that ultimately led to the discovery that secreted and integral membrane proteins also utilize several components that constitute the cytoplasmic quality control machinery. This component of the cellular quality control pathway is known as ER associated degradation, or ERAD. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum. Copyright © 2013 Elsevier B.V. All rights reserved.

Modeling Degradation Product Partitioning in Chlorinated-DNAPL Source Zones

Science.gov (United States)

Boroumand, A.; Ramsburg, A.; Christ, J.; Abriola, L.

2009-12-01

Metabolic reductive dechlorination degrades aqueous phase contaminant concentrations, increasing the driving force for DNAPL dissolution. Results from laboratory and field investigations suggest that accumulation of cis-dichloroethene (cis-DCE) and vinyl chloride (VC) may occur within DNAPL source zones. The lack of (or slow) degradation of cis-DCE and VC within bioactive DNAPL source zones may result in these dechlorination products becoming distributed among the solid, aqueous, and organic phases. Partitioning of cis-DCE and VC into the organic phase may reduce aqueous phase concentrations of these contaminants and result in the enrichment of these dechlorination products within the non-aqueous phase. Enrichment of degradation products within DNAPL may reduce some of the advantages associated with the application of bioremediation in DNAPL source zones. Thus, it is important to quantify how partitioning (between the aqueous and organic phases) influences the transport of cis-DCE and VC within bioactive DNAPL source zones. In this work, abiotic two-phase (PCE-water) one-dimensional column experiments are modeled using analytical and numerical methods to examine the rate of partitioning and the capacity of PCE-DNAPL to reversibly sequester cis-DCE. These models consider aqueous-phase, nonaqueous phase, and aqueous plus nonaqueous phase mass transfer resistance using linear driving force and spherical diffusion expressions. Model parameters are examined and compared for different experimental conditions to evaluate the mechanisms controlling partitioning. Biot number, a dimensionless number which is an index of the ratio of the aqueous phase mass transfer rate in boundary layer to the mass transfer rate within the NAPL, is used to characterize conditions in which either or both processes are controlling. Results show that application of a single aqueous resistance is capable to capture breakthrough curves when DNAPL is distributed in porous media as low

Microbial surface displayed enzymes based biofuel cell utilizing degradation products of lignocellulosic biomass for direct electrical energy.

Science.gov (United States)

Fan, Shuqin; Hou, Chuantao; Liang, Bo; Feng, Ruirui; Liu, Aihua

2015-09-01

In this work, a bacterial surface displaying enzyme based two-compartment biofuel cell for the direct electrical energy conversion from degradation products of lignocellulosic biomass is reported. Considering that the main degradation products of the lignocellulose are glucose and xylose, xylose dehydrogenase (XDH) displayed bacteria (XDH-bacteria) and glucose dehydrogenase (GDH) displayed bacteria (GDH-bacteria) were used as anode catalysts in anode chamber with methylene blue as electron transfer mediator. While the cathode chamber was constructed with laccase/multi-walled-carbon nanotube/glassy-carbon-electrode. XDH-bacteria exhibited 1.75 times higher catalytic efficiency than GDH-bacteria. This assembled enzymatic fuel cell exhibited a high open-circuit potential of 0.80 V, acceptable stability and energy conversion efficiency. Moreover, the maximum power density of the cell could reach 53 μW cm(-2) when fueled with degradation products of corn stalk. Thus, this finding holds great potential to directly convert degradation products of biomass into electrical energy. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Inhibitory Effect of Natural Products on Protein Fibrillation May Be Caused by Degradation Products – A Study Using Aloin and Insulin

DEFF Research Database (Denmark)

Lobbens, Eva Stephanie; Foderà, Vito; Nyberg, Nils

2016-01-01

, high-performance liquid chromatography and transmission electron microscopy it was found that a degradation product of aloin, formed over weeks of storage, was able to significantly inhibit insulin fibrillation. The activity of the stored aloin was significantly reduced in the presence of small amounts...... of sodium azide or ascorbic acid, suggesting the active compound to be an oxidation product. A high-performance liquid chromatography method and a liquid chromatography-mass spectrometry method were developed to investigate the degradation products in the aged aloin solution. We found that the major...

Biodegradation of the alkaline cellulose degradation products generated during radioactive waste disposal.

Science.gov (United States)

Rout, Simon P; Radford, Jessica; Laws, Andrew P; Sweeney, Francis; Elmekawy, Ahmed; Gillie, Lisa J; Humphreys, Paul N

2014-01-01

The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP) including α and β forms of isosaccharinic acid (ISA) and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates. No significant difference (n = 6, p = 0.118) in α and β ISA degradation rates were seen under either iron reducing, sulphate reducing or methanogenic conditions, giving an overall mean degradation rate of 4.7 × 10(-2) hr(-1) (SE ± 2.9 × 10(-3)). These results suggest that a radioactive waste disposal site is likely to be colonised by organisms able to degrade CDP and associated ISA's during the construction and operational phase of the facility.

Infection-Induced Thrombin Production: A Potential Novel Mechanism for Preterm Premature Rupture of Membranes (PPROM).

Science.gov (United States)

Feng, Liping; Allen, Terrence K; Marinello, William P; Murtha, Amy P

2018-04-13

Preterm premature rupture of membranes (PPROM) is a leading contributor to maternal and neonatal morbidity and mortality. Epidemiologic and experimental studies have demonstrated that thrombin causes fetal membrane weakening and subsequently PPROM. Although blood is suspected as the likely source of thrombin in fetal membranes and amniotic fluid of patients with PPROM, this has not been proven. Ureaplasma Parvum (U. parvum) is emerging as a pathogen involved in prematurity, including PPROM, but until now, prothrombin production directly induced by bacteria in fetal membranes has not been described. This study was designed to investigate whether U. parvum exposure can induce prothrombin production in fetal membranes cells. Primary fetal membrane cells (amnion epithelial, chorion trophoblast, and decidua stromal) or full-thickness fetal membrane tissue explants from elective, term, uncomplicated cesarean deliveries were harvested. Cells or tissue explants were infected with live U. parvum (1 x 10 5 , 1 x 10 6 , or 1 x 10 7 colony forming units (cfu)/ml) or lipopolysaccharide (Escherichia coli J5, L-5014, Sigma, 100 ng/ml or 1000 ng/ml) for 24 hours. Tissue explants were fixed for immunohistochemistry staining of thrombin/prothrombin. Fetal membrane cells were fixed for confocal immunofluorescent staining of the biomarkers of fetal membrane cell types and thrombin/prothrombin. Protein and mRNA were harvested from the cells and tissue explants for Western blot or qRT-PCR to quantify thrombin/prothrombin protein or mRNA production, respectively. Data are presented as mean values ± standard errors of mean. Data were analyzed using one-way ANOVA with post hoc Dunnett's test. Prothrombin production and localization was confirmed by Western blot and immunostainings in all primary fetal membrane cells and tissue explants. Immunofluorescence observations revealed a perinuclear localization of prothrombin in amnion epithelial cells. Localization of prothrombin in chorion and

Radiolytic gas production in the alpha particle degradation of plastics

International Nuclear Information System (INIS)

Reed, D.T.; Hoh, J.; Emery, J.; Hobbs, D.

1992-01-01

Net gas generation due to alpha particle irradiation of polyethylene and polyvinyl chloride was investigated. Experiments were performed in an air environment at 30, 60, and 100 degree C. The predominant radiolytic degradation products of polyethylene were hydrogen and carbon dioxide with a wide variety of trace organic species noted. Irradiation of polyvinyl chloride resulted in the formation of HCl in addition to the products observed for polyethylene. For both plastic materials, a strong enhancement of net yields was noted at 100 degree C

Membrane treatment of alkaline bleaching effluents from elementary chlorine free kraft softwood cellulose production.

Science.gov (United States)

Oñate, Elizabeth; Rodríguez, Edgard; Bórquez, Rodrigo; Zaror, Claudio

2015-01-01

This paper reports experimental results on the sequential use of ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) to fractionate alkaline extraction bleaching effluents from kraft cellulose production. The aim was to unveil the way key pollutants are distributed when subjected to sequential UF/NF/RO membrane separation processes. Alkaline bleaching effluents were obtained from a local pinewood-based mill, featuring elementary chlorine free bleaching to produce high-brightness cellulose. The experimental system was based on a laboratory-scale membrane system, DSS LabStak® M20 Alfa Laval, using Alfa Laval UF and NF/RO membranes, operated at a constant transmembrane pressure (6 bar for UF membranes and 32 bar for NF/RO membranes), at 25°C. Results show that 78% chemical oxygen demand (COD) and total phenols, 82% adsorbable organic halogens (AOX) and 98% colour were retained by UF membranes which have molecular weight cut-off (MWCO) above 10 kDa. In all, 16% of original COD, total phenols and AOX, and the remaining 2% colour were retained by UF membranes within the 1 to 10 kDa MWCO range. Chloride ions were significantly present in all UF permeates, and RO was required to obtain a high-quality permeate with a view to water reuse. It is concluded that UF/NF/RO membranes offer a feasible option for water and chemicals recovery from alkaline bleaching effluents in kraft pulp production.

Polymeric membranes for guided bone regeneration.

Science.gov (United States)

Gentile, Piergiorgio; Chiono, Valeria; Tonda-Turo, Chiara; Ferreira, Ana M; Ciardelli, Gianluca

2011-10-01

In this review, different barrier membranes for guided bone regeneration (GBR) are described as a useful surgical technique to enhance bone regeneration in damaged alveolar sites before performing implants and fitting other dental appliances. The GBR procedure encourages bone regeneration through cellular exclusion and avoids the invasion of epithelial and connective tissues that grow at the defective site instead of bone tissue. The barrier membrane should satisfy various properties, such as biocompatibility, non-immunogenicity, non-toxicity, and a degradation rate that is long enough to permit mechanical support during bone formation. Other characteristics such as tissue integration, nutrient transfer, space maintenance and manageability are also of interest. In this review, various non-resorbable and resorbable commercially available membranes are described, based on expanded polytetrafluoroethylene, poly(lactic acid), poly(glycolic acid) and their copolymers. The polyester-based membranes are biodegradable, permit a single-stage procedure, and have higher manageability than non-resorbable membranes; however, they have shown poor biocompatibility. In contrast, membranes based on natural materials, such as collagen, are biocompatible but are characterized by poor mechanical properties and stability due to their early degradation. Moreover, new approaches are described, such as the use of multi-layered, graft-copolymer-based and composite membranes containing osteoconductive ceramic fillers as alternatives to conventional membranes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Membrane engineering - A novel strategy to enhance the production and accumulation of β-carotene in Escherichia coli.

Science.gov (United States)

Wu, Tao; Ye, Lijun; Zhao, Dongdong; Li, Siwei; Li, Qingyan; Zhang, Bolin; Bi, Changhao; Zhang, Xueli

2017-09-01

Carotenoids are a class of terpenes of commercial interest that exert important biological functions. While various strategies have been applied to engineer β-carotene production in microbial cell factories, no work has been done to study and improve the storage of hydrophobic terpene products inside the heterologous host cells. Although the membrane is thought to be the cell compartment that accumulates hydrophobic terpenes such as β-carotene, direct evidence is still lacking. In this work, we engineered the membrane of Escherichia coli in both its morphological and biosynthetic aspects, as a means to study and improve its storage capacity for β-carotene. Engineering the membrane morphology by overexpressing membrane-bending proteins resulted in a 28% increase of β-carotene specific producton value, while engineering the membrane synthesis pathway led to a 43% increase. Moreover, the combination of these two strategies had a synergistic effect, which caused a 2.9-fold increase of β-carotene specific production value (from 6.7 to 19.6mg/g DCW). Inward membrane stacks were observed in electron microscopy images of the engineered E. coli cells, which indicated that morphological changes were associated with the increased β-carotene storage capacity. Finally, membrane separation and analysis confirmed that the increased β-carotene was mainly accumulated within the cell membrane. This membrane engineering strategy was also applied to the β-carotene hyperproducing strain CAR025, which led to a 39% increase of the already high β-carotene specific production value (from 31.8 to 44.2mg/g DCW in shake flasks), resulting in one of the highest reported specific production values under comparable culture conditions. The membrane engineering strategy developed in this work opens up a new direction for engineering and improving microbial terpene producers. It is quite possible that a wide range of strains used to produce hydrophobic compounds can be further improved

Patterned ion exchange membranes for improved power production in microbial reverse-electrodialysis cells

KAUST Repository

Liu, Jia

2014-12-01

Power production in microbial reverse-electrodialysis cells (MRCs) can be limited by the internal resistance of the reverse electrodialysis stack. Typical MRC stacks use non-conductive spacers that block ion transport by the so-called spacer shadow effect. These spacers can be relatively thick compared to the membrane, and thus they increase internal stack resistance due to high solution (ohmic) resistance associated with a thick spacer. New types of patterned anion and cation exchange membranes were developed by casting membranes to create hemispherical protrusions on the membranes, enabling fluid flow between the membranes without the need for a non-conductive spacer. The use of the patterned membrane decreased the MRC stack resistance by ∼22 Ω, resulting in a 38% increase in power density from 2.50 ± 0.04 W m-2 (non-patterned membrane with a non-conductive spacer) to 3.44 ± 0.02 W m-2 (patterned membrane). The COD removal rate, coulombic efficiency, and energy efficiency of the MRC also increased using the patterned membranes compared to the non-patterned membranes. These results demonstrate that these patterned ion exchange membranes can be used to improve performance of an MRC. © 2014 Elsevier B.V. All rights reserved.

Fabrication of electrospun polyacrylonitrile ion-exchange membranes for application in lysozyme adsorption

Directory of Open Access Journals (Sweden)

2011-04-01

Full Text Available Ion exchange (IEX chromatography is commonly used in separation and purification systems. However, micropore blockage within its resin structure can easily lead to a reduction in the effectiveness of purification. To tackle this problem, we adopted the concept of membrane separation by combining electrospinning techniques with rapid alkaline hydrolysis to prepare a weak acid IEX nanofibrous membrane (AEA-COOH, consisting of polyethyleneterephthalate (PET meltblown fabric as a supporting layer, with upper and lower IEX layers consisting of polyacrylonitrile (PAN nanofibrous membranes. To determine the characteristics of the AEA-COOH membrane, we used the commercial product Sartobind© C IEX membrane as the standard of comparison. Results showed that the base weight and thickness of AEACOOH were 33 and 64%, relative to Sartobind© C membrane. The thermo-degradable temperature of AEA-COOH membrane (320°C was far higher than that of Sartobind© C (115°C, indicating high thermal stability. Finally, comparisons between the lysozyme adsorption rates and capacity of various IEX membranes confirmed that AEA-COOH was lighter, thinner, faster, possessing higher protein adsorption efficiency than Sartobind© C membrane.

Technical Performance and Economic Evaluation of Evaporative and Membrane-Based Concentration for Biomass-Derived Sugars

International Nuclear Information System (INIS)

Sievers, David A.; Stickel, Jonathan J.; Grundl, Nicholas J.; Tao, Ling

2017-01-01

Several conversion pathways of lignocellulosic biomass to advanced biofuels require or benefit from using concentrated sugar syrups of 600 g/L or greater. And while concentration may seem straightforward, thermal sugar degradation and energy efficiency remain major concerns. This study evaluated the trade-offs in product recovery, energy consumption, and economics between evaporative and membrane-based concentration methods. The degradation kinetics of xylose and glucose were characterized and applied to an evaporator process simulation. Though significant sugar loss was predicted for certain scenarios due to the Maillard reaction, industrially common falling-film plate evaporators offer short residence times (<5 min) and are expected to limit sugar losses. Membrane concentration experiments characterized flux and sugar rejection, but diminished flux occurred at >100 g/L. A second step using evaporation is necessary to achieve target concentrations. Techno-economic process model simulations evaluated the overall economics of concentrating a 35 g/L sugar stream to 600 g/L in a full-scale biorefinery. A two-step approach of preconcentrating using membranes and finishing with an evaporator consumed less energy than evaporation alone but was more expensive because of high capital expenses of the membrane units.

Ruminal degradation kinetics of protein foods by in vitro gas production technique

Directory of Open Access Journals (Sweden)

Ivone Yurika Mizubuti

2014-02-01

Full Text Available Chemical analysis of carbohydrates and nitrogen fractions, as well as, determination their carbohydrates digestion rates in soyben meal (SM, crambe meal (CM, radish meal (RM, wet brewery residue (WBR and dehydrated silkworm chrysalis (SCD were accomplished. The kinetics parameters of non-fibrous carbohydrates (NFC and B2 fraction were estimated using cumulative gas production technique. Among the foods studied there was considerable variation in chemical composition. The crambe meal was the only food that did not present synchronism between carbohydrate and nitrogen fractions. In this food there was predominance of A+B1 carbohydrates fractions and B1+B2 nitrogen compounds fraction, and for the other predominated B2 carbohydrate fraction and B1+ B2 nitrogen compounds fraction. There were differences among the digestive kinetic parameters for all foods. The greater participation in gas production due to non-fibrous carbohydrates was found in the crambe meal and oilseed radish meal. The fermentation of fibrous carbohydrates provided higher gas volume in the wet brewery residue and in the soybean meal, however, the soybean meal was food with higher total gas volume. Non fibrous carbohydrates degradation rates of wet brewery residue and dehydrated silkworm chrysalis were far below the limits of degradation of this fraction. Due to the parameters obtained by the cumulative gas production, the soybean meal was the best food, however, all others have potential for use in animal nutrition. The cumulative gas production technique allows the estimative of degradation rates and provides further information about the ruminal fermentation kinetics of foods.

Maize production and land degradation: a Portuguese agriculture field case study

Science.gov (United States)

Ferreira, Carla S. S.; Pato, João V.; Moreira, Pedro M.; Valério, Luís M.; Guilherme, Rosa; Casau, Fernando J.; Santos, Daniela; Keizer, Jacob J.; Ferreira, António J. D.

2016-04-01

While food security is a main challenge faced by human kind, intensive agriculture often leads to soil degradation which then can threaten productivity. Maize is one of the most important crops across the world, with 869 million tons produced worldwide in 2012/2013 (IGC 2015), of which 929.5 thousand tons in Portugal (INE 2014). In Portugal, maize is sown in April/May and harvest occurs generally in October. Conventional maize production requires high inputs of water and fertilizers to achieve higher yields. As Portuguese farmers are typically rather old (on average, 63 years) and typically have a low education level (INE 2014), sustainability of their land management practises is often not a principal concern. This could explain why, in 2009, only 4% of the Portuguese temporary crops were under no-tillage, why only 8% of the farmers performed soil analyses in the previous three years, and why many soils have a low organic matter content (INE 2014). Nonetheless, sustainable land management practices are generally accepted to be the key to reducing agricultural soil degradation, preventing water pollution, and assuring long-term crop production objectives and food security. Sustainable land management should therefore not only be a concern for policy makers but also for farmers, since land degradation will have negative repercussions on the productivity, thus, on their economical income. This paper aims to assess the impact of maize production on soil properties. The study focusses on an 8 ha maize field located in central Portugal, with a Mediterranean climate on a gently sloping terrain (<3%) and with a soil classified as Eutric Fluvisol. On the field, several experiments were carried out with different maize varieties as well as with different fertilizers (solid, liquid and both). Centre pivot irrigation was largely used. Data is available from 2003, and concerns crop yield, fertilization and irrigation practices, as well as soil properties assessed through

Structural characterization of chemical warfare agent degradation products in decontamination solutions with proton band-selective (1)H-(31)P NMR spectroscopy.

Science.gov (United States)

Koskela, Harri; Hakala, Ullastiina; Vanninen, Paula

2010-06-15

Decontamination solutions, which are usually composed of strong alkaline chemicals, are used for efficient detoxification of chemical warfare agents (CWAs). The analysis of CWA degradation products directly in decontamination solutions is challenging due to the nature of the matrix. Furthermore, occasionally an unforeseen degradation pathway can result in degradation products which could be eluded to in standard analyses. Here, we present the results of the application of proton band-selective (1)H-(31)P NMR spectroscopy, i.e., band-selective 1D (1)H-(31)P heteronuclear single quantum coherence (HSQC) and band-selective 2D (1)H-(31)P HSQC-total correlation spectroscopy (TOCSY), for ester side chain characterization of organophosphorus nerve agent degradation products in decontamination solutions. The viability of the approach is demonstrated with a test mixture of typical degradation products of nerve agents sarin, soman, and VX. The proton band-selective (1)H-(31)P NMR spectroscopy is also applied in characterization of unusual degradation products of VX in GDS 2000 solution.

By-products formation during degradation of isoproturon in aqueous solution. II: Chlorination.

Science.gov (United States)

Mascolo, G; Lopez, A; James, H; Fielding, M

2001-05-01

After a previous study in which the considered oxidant was ozone (Part I), a laboratory investigation has been carried out to study the degradation of the herbicide isoproturon during its reaction with another oxidant, i.e. chlorine, in aqueous solution (Part II; this paper). The specific aim was to identify the by-products formed. The effects of pH and the presence of bromide ions were studied. Reactions have been carried out at room temperature, in phosphate buffered aqueous solutions, at four pHs (6, 7, 8 and 9). By-products identification was first performed using relatively high initial reagent concentrations which were analytically convenient ([isoproturon] = 40 mg/l, [HClO + ClO-] = 160 mg Cl/l, [Br-] = 80 mg/l). In follow-up studies, the by-products identified during this preliminary step were searched for when using concentration values closer to those actually encountered at real water treatment plants ([isoproturon] = 0.4 and 0.004 mg/l, [HClO + ClO-] = 1.6 mg Cl/l, [Br-] = 0.8 and 0.008 mg/l). Under all of the studied conditions, the results showed that isoproturon is completely degraded and that it decays much faster in the presence of bromide. The pH has a negligible influence when bromide ions are absent. On the contrary, if bromide ions are present, the isoproturon decay is slower at higher pH values. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses have led to the identification of several by-products as a result of simultaneous oxidation and substitution reactions, both occurring on the aromatic ring of the herbicide. However, the more abundant by-products are those resulting from the oxidation of the isoproturon aromatic ring. As far as halogenated by-products are concerned, the higher the bromide ion concentration the higher the ratio of brominated to chlorinated by-products. On the basis of the analytical results, a pathway for isoproturon degradation under the studied conditions is proposed.

Using membrane transporters to improve crops for sustainable food production

Science.gov (United States)

With the global population predicted to grow by at least 25% by 2050, the need for sustainable production of nutritious foods is critical for human and environmental well-being. Recent advances show that specialized plant membrane transporters can be utilized to enhance yields of staple crops, incre...

Comparison of filtration and treatment performance between polymeric and ceramic membranes in anaerobic membrane bioreactor treatment of domestic wastewater

KAUST Repository

Jeong, Yeongmi

2018-02-28

The feasibility of an anaerobic ceramic membrane bioreactor (AnCMBR) was investigated by comparison with a conventional anaerobic membrane bioreactor (AnMBR). With regard to treatment performance, the AnCMBR achieved higher organic removal rates than the AnMBR because the ceramic membranes retained a high concentration of biomass in the reactor. Despite a high mixed liquor suspended solid (MLSS) concentration, the AnCMBR exhibited lower membrane fouling. To elucidate effects of sludge properties on membrane fouling in the AnCMBR and AnMBR, soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) were analyzed. The SMP and EPS concentrations in the AnCMBR were higher than in the AnMBR. This may be because some suspended solids bio-degraded and likely released protein-like SMPs in the AnCMBR. Hydrophobicity and surface charges were analyzed; the sludge in the AnCMBR was found to be more hydrophobic and less negative than in the AnMBR because protein was abundant in the AnCMBR. Despite the adverse properties of the sludge in the AnCMBR, it showed more stable filtration performance than the AnMBR. This is because the alumina-based ceramic membrane had a superhydrophilic surface and could thus mitigate membrane fouling by hydrophilic-hydrophobic repulsion. The findings from this study have significant implications for extending the application of AnCMBRs to, for example, treatment of high-strength organic waste such as food waste or livestock manure.

Comparison of filtration and treatment performance between polymeric and ceramic membranes in anaerobic membrane bioreactor treatment of domestic wastewater

KAUST Repository

Jeong, Yeongmi; Kim, Youngjin; Jin, Yongxun; Hong, Seungkwan; Park, Chanhyuk

2018-01-01

The feasibility of an anaerobic ceramic membrane bioreactor (AnCMBR) was investigated by comparison with a conventional anaerobic membrane bioreactor (AnMBR). With regard to treatment performance, the AnCMBR achieved higher organic removal rates than the AnMBR because the ceramic membranes retained a high concentration of biomass in the reactor. Despite a high mixed liquor suspended solid (MLSS) concentration, the AnCMBR exhibited lower membrane fouling. To elucidate effects of sludge properties on membrane fouling in the AnCMBR and AnMBR, soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) were analyzed. The SMP and EPS concentrations in the AnCMBR were higher than in the AnMBR. This may be because some suspended solids bio-degraded and likely released protein-like SMPs in the AnCMBR. Hydrophobicity and surface charges were analyzed; the sludge in the AnCMBR was found to be more hydrophobic and less negative than in the AnMBR because protein was abundant in the AnCMBR. Despite the adverse properties of the sludge in the AnCMBR, it showed more stable filtration performance than the AnMBR. This is because the alumina-based ceramic membrane had a superhydrophilic surface and could thus mitigate membrane fouling by hydrophilic-hydrophobic repulsion. The findings from this study have significant implications for extending the application of AnCMBRs to, for example, treatment of high-strength organic waste such as food waste or livestock manure.

Large-scale bioreactor production of the herbicide-degrading Aminobacter sp. strain MSH1

DEFF Research Database (Denmark)

Schultz-Jensen, Nadja; Knudsen, Berith Elkær; Frkova, Zuzana

2014-01-01

The Aminobacter sp. strain MSH1 has potential for pesticide bioremediation because it degrades the herbicide metabolite 2,6-dichlorobenzamide (BAM). Production of the BAM-degrading bacterium using aerobic bioreactor fermentation was investigated. A mineral salt medium limited for carbon and with ......The Aminobacter sp. strain MSH1 has potential for pesticide bioremediation because it degrades the herbicide metabolite 2,6-dichlorobenzamide (BAM). Production of the BAM-degrading bacterium using aerobic bioreactor fermentation was investigated. A mineral salt medium limited for carbon...... and with an element composition similar to the strain was generated. The optimal pH and temperature for strain growth were determined using shaker flasks and verified in bioreactors. Glucose, fructose, and glycerol were suitable carbon sources for MSH1 (μ =0.1 h−1); slower growth was observed on succinate and acetic...... acid (μ =0.01 h−1). Standard conditions for growth of theMSH1 strain were defined at pH 7 and 25 °C, with glucose as the carbon source. In bioreactors (1 and 5 L), the specific growth rate of MSH1 increased from μ =0.1 h−1 on traditional mineral salt medium to μ =0.18 h−1 on the optimized mineral salt...

Novel Water Treatment Processes Based on Hybrid Membrane-Ozonation Systems: A Novel Ceramic Membrane Contactor for Bubbleless Ozonation of Emerging Micropollutants

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Stylianos K. Stylianou

2015-01-01

Full Text Available The aim of this study is the presentation of novel water treatment systems based on ozonation combined with ceramic membranes for the treatment of refractory organic compounds found in natural water sources such as groundwater. This includes, firstly, a short review of possible membrane based hybrid processes for water treatment from various sources. Several practical and theoretical aspects for the application of hybrid membrane-ozonation systems are discussed, along with theoretical background regarding the transformation of target organic pollutants by ozone. Next, a novel ceramic membrane contactor, bringing into contact the gas phase (ozone and water phase without the creation of bubbles (bubbleless ozonation, is presented. Experimental data showing the membrane contactor efficiency for oxidation of atrazine, endosulfan, and methyl tert-butyl ether (MTBE are shown and discussed. Almost complete endosulfan degradation was achieved with the use of the ceramic contactor, whereas atrazine degradation higher than 50% could not be achieved even after 60 min of reaction time. Single ozonation of water containing MTBE could not result in a significant MTBE degradation. MTBE mineralization by O3/H2O2 combination increased at higher pH values and O3/H2O2 molar ratio of 0.2 reaching a maximum of around 65%.

Identification of degradation products of ionic liquids in an ultrasound assisted zero-valent iron activated carbon micro-electrolysis system and their degradation mechanism.

Science.gov (United States)

Zhou, Haimei; Lv, Ping; Shen, Yuanyuan; Wang, Jianji; Fan, Jing

2013-06-15

Ionic liquids (ILs) have potential applications in many areas of chemical industry because of their unique properties. However, it has been shown that the ILs commonly used to date are toxic and not biodegradable in nature, thus development of efficient chemical methods for the degradation of ILs is imperative. In this work, degradation of imidazolium, piperidinium, pyrrolidinium and morpholinium based ILs in an ultrasound and zero-valent iron activated carbon (ZVI/AC) micro-electrolysis system was investigated, and some intermediates generated during the degradation were identified. It was found that more than 90% of 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br, n = 2, 4, 6, 8, 10) could be degraded within 110 min, and three intermediates 1-alkyl-3-methyl-2,4,5-trioxoimidazolidine, 1-alkyl-3-methylurea and N-alkylformamide were detected. On the other hand, 1-butyl-1-methylpiperidinium bromide ([C4mpip]Br), 1-butyl-1-methylpyrrolidinium bromide ([C4mpyr]Br) and N-butyl-N-methylmorpholinium bromide ([C4mmor]Br) were also effectively degraded through the sequential oxidization into hydroxyl, carbonyl and carboxyl groups in different positions of the butyl side chain, and then the N-butyl side chain was broken to form the final products of N-methylpiperidinium, N-methylpyrrolidinium and N-methylmorpholinium, respectively. Based on these intermediate products, degradation pathways of these ILs were suggested. These findings may provide fundamental information on the assessment of the factors related to the environmental fate and environmental behavior of these commonly used ILs. Copyright © 2013 Elsevier Ltd. All rights reserved.

Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole on nanocrystalline titania films in alkaline media: Effect of applied electrical bias on degradation and transformation products

Energy Technology Data Exchange (ETDEWEB)

Tantis, Iosif [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); Bousiakou, Leda [Department of Physics and Astronomy, King Saud University, Riyadh (Saudi Arabia); Department of Automation Engineering, Technological Educational Institute of Pireaus, GR-12244 Athens (Greece); Frontistis, Zacharias; Mantzavinos, Dionissios [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); Konstantinou, Ioannis; Antonopoulou, Maria [Department of Environmental and Natural Resources Management, University of Patras, GR-30100 Agrinio (Greece); Karikas, George-Albert [Department of Medical Laboratories Technology, Technological Educational Institute of Athens, 12210 Athens (Greece); Lianos, Panagiotis, E-mail: lianos@upatras.gr [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); FORTH/ICE-HT, P.O. Box 1414, GR-26504 Patras (Greece)

2015-08-30

Highlights: • Photocatalytic and photoelectrocatalytic degradation of the proton pump omeprazole. • Improvement of photocatalysis rate by applying a moderate forward bias. • Highlighting of the advantages of photoelectrocatalysis in a straightforward manner. • HPLC and HR-LC–MS analysis of transformation products. - Abstract: Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole has been studied in the presence of nanocrystalline titania films supported on glass slides or transparent FTO electrodes in alkaline environment. Its photocatalytic degradation rate was assessed by its UV absorbance and by HPLC, while its transformation products were analyzed by HR-LC–MS. Based on UV absorbance, omeprazole can be photocatalytically degraded at an average rate of 6.7 × 10{sup −4} min{sup −1} under low intensity UVA irradiation of 1.5 mW cm{sup −2} in the presence of a nanoparticulate titania film. This corresponds to degradation of 1.4 mg of omeprazole per gram of the photocatalyst per liter of solution per hour. The photodegradation rate can be accelerated in a photoelectrochemical cell by applying a forward bias. In this case, the maximum rate reached under the present conditions was 11.6 × 10{sup −4} min{sup −1} by applying a forward bias of +0.6 V vs. Ag/AgCl. Four major transformation products were successfully identified and their profiles were followed by HR-LC–MS. The major degradation path includes the scission of the sulfoxide bridge into the corresponding pyridine and benzimidazole ring derivates and this is accompanied by the release of sulfate anions in the reaction mixture.

Reverse membrane bioreactor: Introduction to a new technology for biofuel production.

Science.gov (United States)

Mahboubi, Amir; Ylitervo, Päivi; Doyen, Wim; De Wever, Heleen; Taherzadeh, Mohammad J

2016-01-01

The novel concept of reverse membrane bioreactors (rMBR) introduced in this review is a new membrane-assisted cell retention technique benefiting from the advantageous properties of both conventional MBRs and cell encapsulation techniques to tackle issues in bioconversion and fermentation of complex feeds. The rMBR applies high local cell density and membrane separation of cell/feed to the conventional immersed membrane bioreactor (iMBR) set up. Moreover, this new membrane configuration functions on basis of concentration-driven diffusion rather than pressure-driven convection previously used in conventional MBRs. These new features bring along the exceptional ability of rMBRs in aiding complex bioconversion and fermentation feeds containing high concentrations of inhibitory compounds, a variety of sugar sources and high suspended solid content. In the current review, the similarities and differences between the rMBR and conventional MBRs and cell encapsulation regarding advantages, disadvantages, principles and applications for biofuel production are presented and compared. Moreover, the potential of rMBRs in bioconversion of specific complex substrates of interest such as lignocellulosic hydrolysate is thoroughly studied. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Characterization of degradation products from alkaline wet oxidation of wheat straw

DEFF Research Database (Denmark)

Klinke, H.B.; Ahring, B.K.; Schmidt, A.S.

2002-01-01

to their chemical structure, e.g. diacids (oxalic and succinic acids), furan aldehydes, phenol aldehydes, phenol ketones and phenol acids. Aromatic aldehyde formation was correlated to severe conditions with high temperatures and low pH. Apart from CO2 and water, carboxylic acids were the main degradation products...... degreesC with addition of 12 bar oxygen and 6.5 g l(-1) Na2CO3. At these conditions the hemicellulose fraction from 100 g straw consisted of soluble hemicellulose (16 g), low molecular weight carboxylic acids (11 g), monomeric phenols (0.48 g) and 2-furoic acid (0.01 g). Formic acid and acetic acid...... constituted the majority of degradation products (8.5 g). The main phenol monomers were 4-hydroxybenzaldehyde, vanillin, syringaldehyde, acetosyringone (4-hydroxy-3,5-dimethoxy-acetophenone), vanillic acid and syringic acid, occurring in 0.04-0.12 g per 100 g straw concentrations. High lignin removal from...

Biocatalytic Self-Cleaning Polymer Membranes

Directory of Open Access Journals (Sweden)

Agnes Schulze

2015-09-01

Full Text Available Polymer membrane surfaces have been equipped with the digestive enzyme trypsin. Enzyme immobilization was performed by electron beam irradiation in aqueous media within a one-step method. Using this method, trypsin was covalently and side-unspecific attached to the membrane surface. Thus, the use of preceding polymer functionalization and the use of toxic solvents or reagents can be avoided. The resulting membranes showed significantly improved antifouling properties as demonstrated by repeated filtration of protein solutions. Furthermore, the biocatalytic membrane can be simply “switched on” to actively degrade a fouling layer on the membrane surface and regain the initial permeability. The membrane pore structure (pore size and porosity was neither damaged by the electron beam treatment nor blocked by the enzyme loading, ensuring a stable membrane performance.

Phytase production by Aspergillus niger NCIM 563 for a novel application to degrade organophosphorus pesticides.

Science.gov (United States)

Shah, Parin C; Kumar, V Ravi; Dastager, Syed G; Khire, Jayant M

2017-12-01

The production of phytase using Aspergillus niger NCIM 563 under submerged fermentation conditions was studied using protein rich chickpea flour as substrate. Employing a hybrid statistical media optimization strategy of Plackett-Burman and Box-Behnken experimental designs in shake-flasks gave an increased phytase activity from an initial 66 IU/mL in 216 h to 160 IU/mL in a reduced time of 132 h. Productivity, thus increased by 3.97 times from 7.3 to 29 IU/mL/day. Using the optimized media, the production was successfully scaled-up further and improved up to 164 IU/mL in 96 h by studies carried out employing 2 and 10-L fermenters. The enzyme supernatant was recovered using centrifugal separation of biomass and the stability of the produced phytase was tested for animal feed applications under gastric conditions. In vitro degradation studies of water soluble monocrotophos, methyl parathion and water insoluble chlorpyrifos, pesticides used extensively in agriculture was carried out. It was observed by HPLC analysis that phytase could degrade 72% of chlorpyrifos at pH 7.0, 35 °C. Comparable results were obtained with monocrotophos and methyl parathion. With chlorpyrifos at higher temperature 50 °C as much as 91% degradation could be obtained. The degradation of chlorpyrifos was further validated by spraying phytase on harvested green chilli (Capsicum annuum L) under normal conditions of pH 7.0, 35 °C and the degradation products obtained analyzed by LCMS. Thus, the present study brings out a potentially novel application of phytase for biodegradation of organophosphorus pesticides.

Rapid quantification of TBP and TBP degradation product ratios by FTIR-ATR

International Nuclear Information System (INIS)

Gillens, A.R.; Powell, B.A.; Clemson University, Clemson, SC

2013-01-01

Tri-n-butyl phosphate (TBP) is the key complexant within the plutonium and uranium reduction extraction process used to extract uranium and plutonium from used nuclear fuel. During reprocessing TBP degrades to dibutyl phosphate (DBP), butyl acid phosphate (MBP), butanol, and phosphoric acid over time. A method for rapidly monitoring TBP degradation is needed for the support of nuclear forensics. Therefore, a Fourier transform infrared spectrometry-attenuated total reflectance (FTIR-ATR) technique was developed to determine approximate peak intensity ratios of TBP and its degradation products. The technique was developed by combining variable concentrations of TBP, DBP, and MBP to simulate TBP degradation. This method is achieved by analyzing selected peak positions and peak intensity ratios of TBP and DBP at different stages of degradation. The developed technique was tested on TBP samples degraded with nitric acid. In mock degradation samples, the 1,235 cm -1 peak position shifts to 1,220 cm -1 as the concentration of TBP decreases and DBP increases. Peak intensity ratios of TBP positions at 1,279 and 1,020 cm -1 relative to DBP positions at 909 and 1,003 cm -1 demonstrate an increasing trend as the concentration of DBP increases. The same peak intensity ratios were used to analyze DBP relative to MBP whereas a decreasing trend is seen with increasing DBP concentrations. The technique developed from this study may be used as a tool to determine TBP degradation in nuclear reprocessing via a rapid FTIR-ATR measurement without gas chromatography analysis. (author)

Method for determination of methyl tert-butyl ether and its degradation products in water

Science.gov (United States)

Church, C.D.; Isabelle, L.M.; Pankow, J.F.; Rose, D.L.; Tratnyek, P.G.

1997-01-01

An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method can also give simultaneous identification of polar compounds that might occur as degradation products of gasoline oxygenates, such as TBA, TBF, TAA, methyl acetate, and acetone. When the method was applied to effluent from a column microcosm prepared with core material from an urban site in New Jersey, conversion of MTBE to TBA was observed after a lag period of 35 days. However, to date, analyses of water samples from six field sites using the DAI-GC/MS method have not produced evidence for the expected products of in situ degradation of MTBE.An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method

Hydrogen and Carbon Black Production from the Degradation of Methane by Thermal Plasma

Directory of Open Access Journals (Sweden)

Leila Cottet

2014-05-01

Full Text Available Methane gas (CH4 is the main inducer of the so called greenhouse gases effect. Recent scientific research aims to minimize the accumulation of this gas in the atmosphere and to develop processes capable of producing stable materials with added value. Thermal plasma technology is a promising alternative to these applications, since it allows obtaining H2 and solid carbon from CH4, without the parallel formation of byproducts such as CO2 and NOx. In this work, CH4 was degraded by thermal plasma in order to produce hydrogen (H2 and carbon black. The degradation efficiency of CH4, selectivity for H2 production as well as the characterization of carbon black were studied. The best results were obtained in the CH4 flow rate of 5 L min-1 the degradation percentage and the selectivity for H2 production reached 98.8 % and 48.4 %, respectively. At flow rates of less than 5 L min-1 the selectivity for H2 production increases and reaches 91.9 %. The carbon black has obtained amorphous with hydrophobic characteristics and can be marketed to be used in composite material, and can also be activated chemically and/or physically and used as adsorbent material.

Internalization, lysosomal degradation and new synthesis of surface membrane CD4 in phorbol ester-activated T-lymphocytes and U-937 cells

DEFF Research Database (Denmark)

Petersen, C M; Christensen, E I; Andresen, B S

1992-01-01

degradation was low in resting cells. Endocytosis and/or degradation of anti-CD4 mAb was suppressed by H7, and by inhibitors of membrane traffic (Monensin) and lysosome function (methylamine, chloroquine). Immunocytochemistry localized CD4 to the surface of unstimulated T-cells. Upon PMA stimulation...... occasional labeling was seen in endosomes but whole cell CD4 decreased dramatically. However, methylamine-treated PMA blasts showed accumulation of CD4 in lysosomes and accordingly, pulse-chase experiments in biolabeled cell cultures suggested a manifest reduction of CD4 half-life in response to PMA. Despite...... in activated cells was further evidenced by metabolic labeling and Northern blot analysis demonstrating unaltered or slightly increased CD4 protein and mRNA levels resulting from PMA. Our findings demonstrate that phorbol esters downregulate the cellular CD4 pool by endocytosis and subsequent lysosomal...

Biodegradation of the alkaline cellulose degradation products generated during radioactive waste disposal.

Directory of Open Access Journals (Sweden)

Simon P Rout

Full Text Available The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP including α and β forms of isosaccharinic acid (ISA and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates. No significant difference (n = 6, p = 0.118 in α and β ISA degradation rates were seen under either iron reducing, sulphate reducing or methanogenic conditions, giving an overall mean degradation rate of 4.7 × 10(-2 hr(-1 (SE ± 2.9 × 10(-3. These results suggest that a radioactive waste disposal site is likely to be colonised by organisms able to degrade CDP and associated ISA's during the construction and operational phase of the facility.

Fate of CL-20 in sandy soils: Degradation products as potential markers of natural attenuation

International Nuclear Information System (INIS)

Monteil-Rivera, Fanny; Halasz, Annamaria; Manno, Dominic; Kuperman, Roman G.; Thiboutot, Sonia; Ampleman, Guy; Hawari, Jalal

2009-01-01

Hexanitrohexaazaisowurtzitane (CL-20) is an emerging explosive that may replace the currently used explosives such as RDX and HMX, but little is known about its fate in soil. The present study was conducted to determine degradation products of CL-20 in two sandy soils under abiotic and biotic anaerobic conditions. Biotic degradation was prevalent in the slightly acidic VT soil, which contained a greater organic C content, while the slightly alkaline SAC soil favored hydrolysis. CL-20 degradation was accompanied by the formation of formate, glyoxal, nitrite, ammonium, and nitrous oxide. Biotic degradation of CL-20 occurred through the formation of its denitrohydrogenated derivative (m/z 393 Da) while hydrolysis occurred through the formation of a ring cleavage product (m/z 156 Da) that was tentatively identified as CH 2 =N-C(=N-NO 2 )-CH=N-CHO or its isomer N(NO 2 )=CH-CH=N-CO-CH=NH. Due to their chemical specificity, these two intermediates may be considered as markers of in situ attenuation of CL-20 in soil. - Two key intermediates of CL-20 degradation are potential markers of its natural attenuation in soil

Nanostructured Ceramic Photocatalytic Membrane Modified with a Polymer Template for Textile Wastewater Treatment

Directory of Open Access Journals (Sweden)

Rizwan Ahmad

2017-12-01

Full Text Available Photocatalytic ceramic membranes have attracted considerable attention for industrial wastewater treatment. However, morphological control of the membrane surface to improve its photocatalytic reactivity for the degradation of organic pollutants remains a challenge. Herein, we report a new nanostructured TiO2/Al2O3 composite ceramic membrane prepared from a poly(oxyethylene methacrylate (POEM template through a sol–gel method and its photocatalytic performance in the treatment of a model dye compound. The POEM polymeric template allowed the homogeneous distribution of catalytic sites, i.e., the TiO2 layer, on the Al2O3 membrane surface, resulting in improved organic dye degradation along with effective fouling mitigation. The immobilization of a TiO2 layer on the Al2O3 membrane support also significantly enhanced the membrane adsorption capacity toward dye organic compounds. An organic removal efficiency of over 96% was achieved with the TiO2/Al2O3 composite membrane under Ultraviolet (UV irradiation. In addition, the self-cleaning efficiency of the TiO2/Al2O3 composite membrane was remarkably improved by the degradation of organic foulants on the membrane under UV illumination.

Membrane-anchored MucR mediates nitrate-dependent regulation of alginate production in Pseudomonas aeruginosa

KAUST Repository

Wang, Yajie

2015-04-29

Alginates exhibit unique material properties suitable for medical and industrial applications. However, if produced by Pseudomonas aeruginosa, it is an important virulence factor in infection of cystic fibrosis patients. The alginate biosynthesis machinery is activated by c-di-GMP imparted by the inner membrane protein, MucR. Here, it was shown that MucR impairs alginate production in response to nitrate in P. aeruginosa. Subsequent site-specific mutagenesis of MucR revealed that the second MHYT sensor motif (MHYT II, amino acids 121–124) of MucR sensor domain was involved in nitrate sensing. We also showed that both c-di-GMP synthesizing and degrading active sites of MucR were important for alginate production. Although nitrate and deletion of MucR impaired alginate promoter activity and global c-di-GMP levels, alginate yields were not directly correlated with alginate promoter activity or c-di-GMP levels, suggesting that nitrate and MucR modulate alginate production at a post-translational level through a localized pool of c-di-GMP. Nitrate increased pel promoter activity in the mucR mutant while in the same mutant the psl promoter activity was independent of nitrate. Nitrate and deletion of mucR did not impact on swarming motility but impaired attachment to solid surfaces. Nitrate and deletion of mucR promoted the formation of biofilms with increased thickness, cell density, and survival. Overall, this study provided insight into the functional role of MucR with respect to nitrate-mediated regulation of alginate biosynthesis. © 2015 Springer-Verlag Berlin Heidelberg

Fate of products of degradation processes: consequences for climatic change

International Nuclear Information System (INIS)

Slanina, J.; Brink, H.M. ten; Khlystov, A.

1999-01-01

The end products of atmospheric degradation are not only CO 2 and H 2 O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due to formation of greenhouse gases but also of aerosols. Aerosols of a diameter of 0.1 to 2 micrometer, reflect short wave sunlight very efficiently leading to a radiative forcing which is estimated to be about -0.8 watt per m 2 by IPCC. Aerosols also influence the radiative balance by way of cloud formation. If more aerosols are present, clouds are formed with more and smaller droplets and these clouds have a higher albedo and are more stable compared to clouds with larger droplets. Not only sulfate, but also nitrate and polar organic compounds, formed as intermediates in degradation processes, contribute to this direct and indirect aerosol effect. Estimates for the Netherlands indicate a direct effect of -4 watt m -2 and an indirect effect of as large as -5 watt m -2 . About one third is caused by sulfates, one third by nitrates and last third by polar organic compounds. This large radiative forcing is obviously non-uniform and depends on local conditions. (author)

Analysis of micromixers and biocidal coatings on water-treatment membranes to minimize biofouling.

Energy Technology Data Exchange (ETDEWEB)

Webb, Stephen W.; James, Darryl L. (Texas Tech University, Lubbock, TX); Hibbs, Michael R.; Jones, Howland D. T.; Hart, William Eugene; Khalsa, Siri Sahib; Altman, Susan Jeanne; Clem, Paul Gilbert; Elimelech, Menachem (Yale University, New Haven, CT); Cornelius, Christopher James; Sanchez, Andres L. (LMATA Government Services LLC, Albuquerque, NM); Noek, Rachael M.; Ho, Clifford Kuofei; Kang, Seokatae (Yale University, New Haven, CT); Sun, Amy Cha-Tien; Adout, Atar (Yale University, New Haven, CT); McGrath, Lucas K. (LMATA Government Services LLC, Albuquerque, NM); Cappelle, Malynda A.; Cook, Adam W.

2009-12-01

Biofouling, the unwanted growth of biofilms on a surface, of water-treatment membranes negatively impacts in desalination and water treatment. With biofouling there is a decrease in permeate production, degradation of permeate water quality, and an increase in energy expenditure due to increased cross-flow pressure needed. To date, a universal successful and cost-effect method for controlling biofouling has not been implemented. The overall goal of the work described in this report was to use high-performance computing to direct polymer, material, and biological research to create the next generation of water-treatment membranes. Both physical (micromixers - UV-curable epoxy traces printed on the surface of a water-treatment membrane that promote chaotic mixing) and chemical (quaternary ammonium groups) modifications of the membranes for the purpose of increasing resistance to biofouling were evaluated. Creation of low-cost, efficient water-treatment membranes helps assure the availability of fresh water for human use, a growing need in both the U. S. and the world.

All electrochemical fabrication of a bilayer membrane composed of nanotubular photocatalyst and palladium toward high-purity hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Hattori, Masashi [Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga 816-8580 (Japan); Noda, Kei, E-mail: nodakei@elec.keio.ac.jp [Department of Electronics and Electrical Engineering, Keio University, Hiyoshi, Yokohama 223-8522 (Japan)

2015-12-01

Graphical abstract: - Highlights: • A bilayer membrane composed of TiO{sub 2} nanotube array and palladium was fabricated. • The TiO{sub 2}/Pd bilayer membrane was prepared with an all-electrochemical process. • The membrane consists of pure Pd and anatase TiO{sub 2} nanotubes with no alloy formation. • Photocatalytic H{sub 2} production and concomitant separation were demonstrated. • High-purity H{sub 2} production rate and apparent quantum yield were evaluated. - Abstract: We developed an all-electrochemical technique for fabricating a bilayer structure of a titanium dioxide (TiO{sub 2}) nanotube array (TNA) and a palladium film (TNA/Pd membrane), which works for photocatalytic high-purity hydrogen production. Electroless plating was used for depositing the Pd film on the TNA surface prepared by anodizing a titanium foil. A 3-μm-thick TNA/Pd membrane without any pinholes in a 1.5-cm-diameter area was fabricated by transferring a 1-μm-thick TNA onto an electroless-plated 2-μm-thick Pd film with a mechanical peel-off process. This ultrathin membrane with sufficient mechanical robustness showed photocatalytic H{sub 2} production via methanol reforming under ultraviolet illumination on the TNA side, immediately followed by the purification of the generated H{sub 2} gas through the Pd layer. The hydrogen production rate and the apparent quantum yield for high-purity H{sub 2} production from methanol/water mixture with the TNA/Pd membrane were also examined. This work suggests that palladium electroless plating is more suitable and practical for preparing a well-organized TNA/Pd heterointerface than palladium sputter deposition.

Process simulation and economic analysis of biodiesel production from waste cooking oil with membrane bioreactor

Science.gov (United States)

Abdurakhman, Yuanita Budiman; Putra, Zulfan Adi; Bilad, Muhammad Roil

2017-10-01

Pollution and shortage of clean energy supply are among major problems that are caused by rapid population growth. Due to this growth, waste cooking oil is one of the pollution sources. On the other hand, biodiesel appears to be one of the most promising and feasible energy sources as it emits less toxic pollutants and greenhouse gases than petroleum diesel. Thus, biodiesel production using waste cooking oil offers a two-in-one solution to cater pollution and energy issues. However, the conventional biodiesel production process using homogeneous base catalyst and stirred tank reactor is unable to produce high purity of biodiesel from waste cooking oil. It is due its sensitivity to free fatty acid (FFA) content in waste cooking oil and purification difficulties. Therefore, biodiesel production using heterogeneous acid catalyst in membrane reactor is suggested. The product of this process is fatty acid methyl esters (FAME) or biodiesel with glycerol as by-product. This project is aimed to study techno-economic feasibility of biodiesel production from waste cooking oil via heterogeneous acid catalyst in membrane reactor. Aspen HYSYS is used to accomplish this aim. Several cases, such as considering different residence times and the production of pharmaceutical (USP) grade glycerol, are evaluated and compared. Economic potential of these cases is calculated by considering capital expenditure, utilities cost, product and by-product sales, as well as raw material costs. Waste cooking oil, inorganic pressure-driven membrane and WAl is used as raw material, type of membrane and heterogeneous acid catalyst respectively. Based on literature data, FAME yield formulation is developed and used in the reactor simulation. Simulation results shows that economic potential increases by 30% if pharmaceutical (USP) grade glycerol is produced regardless the residence time of the reactor. In addition, there is no significant effect of residence time on the economic potential.

Enhanced sulfamethoxazole degradation through ammonia oxidizing bacteria co-metabolism and fate of transformation products.

Science.gov (United States)

Kassotaki, Elissavet; Buttiglieri, Gianluigi; Ferrando-Climent, Laura; Rodriguez-Roda, Ignasi; Pijuan, Maite

2016-05-01

The occurrence of the widely-used antibiotic sulfamethoxazole (SFX) in wastewaters and surface waters has been reported in a large number of studies. However, the results obtained up-to-date have pointed out disparities in its removal. This manuscript explores the enhanced biodegradation potential of an enriched culture of Ammonia Oxidizing Bacteria (AOB) towards SFX. Several sets of batch tests were conducted to establish a link between SFX degradation and specific ammonia oxidation rate. The occurrence, degradation and generation of SFX and some of its transformation products (4-Nitro SFX, Desamino-SFX and N(4)-Acetyl-SFX) was also monitored. A clear link between the degradation of SFX and the nitrification rate was found, resulting in an increased SFX removal at higher specific ammonia oxidation rates. Moreover, experiments conducted under the presence of allylthiourea (ATU) did not present any removal of SFX, suggesting a connection between the AMO enzyme and SFX degradation. Long term experiments (up to 10 weeks) were also conducted adding two different concentrations (10 and 100 μg/L) of SFX in the influent of a partial nitrification sequencing batch reactor, resulting in up to 98% removal. Finally, the formation of transformation products during SFX degradation represented up to 32%, being 4-Nitro-SFX the most abundant. Copyright © 2016 Elsevier Ltd. All rights reserved.

Wood Degradation by Thermotolerant and Thermophilic Fungi for Sustainable Heat Production

NARCIS (Netherlands)

Caizan Juanarena, Leire; ter Heijne, Annemiek; Buisman, Cees; Van der Wal, A.

2016-01-01

The use of renewable biomass for production of heat and electricity plays an important role in the circular economy. Degradation of wood biomass to produce heat is a clean and novel process proposed as an alternative to wood burning, and could be used for various heating applications. So far, wood

The effects of mediator and granular activated carbon addition on degradation of trace organic contaminants by an enzymatic membrane reactor.

Science.gov (United States)

Nguyen, Luong N; Hai, Faisal I; Price, William E; Leusch, Frederic D L; Roddick, Felicity; Ngo, Hao H; Guo, Wenshan; Magram, Saleh F; Nghiem, Long D

2014-09-01

The removal of four recalcitrant trace organic contaminants (TrOCs), namely carbamazepine, diclofenac, sulfamethoxazole and atrazine by laccase in an enzymatic membrane reactor (EMR) was studied. Laccases are not effective for degrading non-phenolic compounds; nevertheless, 22-55% removal of these four TrOCs was achieved by the laccase EMR. Addition of the redox-mediator syringaldehyde (SA) to the EMR resulted in a notable dose-dependent improvement (15-45%) of TrOC removal affected by inherent TrOC properties and loading rates. However, SA addition resulted in a concomitant increase in the toxicity of the treated effluent. A further 14-25% improvement in aqueous phase removal of the TrOCs was consistently observed following a one-off dosing of 3g/L granular activated carbon (GAC). Mass balance analysis reveals that this improvement was not due solely to adsorption but also enhanced biodegradation. GAC addition also reduced membrane fouling and the SA-induced toxicity of the effluent. Copyright © 2014 Elsevier Ltd. All rights reserved.

Rapid and Simultaneous Determination of Acetylsalicylic Acid, Paracetamol, and Their Degradation and Toxic Impurity Products by HPLC in Pharmaceutical Dosage Forms

OpenAIRE

AKAY, Cemal

2008-01-01

Aims: Determinations of drug impurity and drug degradation products are very important from both pharmacological and toxicological perspectives. Establishment of monitoring methods for impurities and degradation products during pharmaceutical development is necessary because of their potential toxicity. The aim of this study was to develop a rapid and simultaneous determination method for paracetamol and acetylsalicylic acid (ACA) and their degradation and toxic impurity products by high perf...

Enhanced mitochondrial degradation of yeast cytochrome c with amphipathic structures.

Science.gov (United States)

Chen, Xi; Moerschell, Richard P; Pearce, David A; Ramanan, Durga D; Sherman, Fred

2005-02-01

The dispensable N-terminus of iso-1-cytochrome c (iso-1) in the yeast Saccharomyces cerevisiae was replaced by 11 different amphipathic structures. Rapid degradation of the corresponding iso-1 occurred, with the degree of degradation increasing with the amphipathic moments; and this amphipathic-dependent degradation was designated ADD. ADD occurred with the holo-forms in the mitochondria but not as the apo-forms in the cytosol. The extreme mutant type degraded with a half-life of approximately 12 min, whereas the normal iso-1 was stable over hours. ADD was influenced by the rho+/rho- state and by numerous chromosomal genes. Most importantly, ADD appeared to be specifically suppressed to various extents by deletions of any of the YME1, AFG3, or RCA1 genes encoding membrane-associated mitochondrial proteases, probably because the amphipathic structures caused a stronger association with the mitochondrial inner membrane and its associated proteases. The use of ADD assisted in the differentiation of substrates of different mitochondrial degradation pathways.

Herp enhances ER-associated protein degradation by recruiting ubiquilins

International Nuclear Information System (INIS)

Kim, Tae-Yeon; Kim, Eunmin; Yoon, Sungjoo Kim; Yoon, Jong-Bok

2008-01-01

ER-associated protein degradation (ERAD) is a protein quality control system of ER, which eliminates misfolded proteins by proteasome-dependent degradation and ensures export of only properly folded proteins from ER. Herp, an ER membrane protein upregulated by ER stress, is implicated in regulation of ERAD. In the present study, we show that Herp interacts with members of the ubiquilin family, which function as a shuttle factor to deliver ubiquitinated substrates to the proteasome for degradation. Knockdown of ubiquilin expression by small interfering RNA stabilized the ERAD substrate CD3δ, whereas it did not alter or increased degradation of non-ERAD substrates tested. CD3δ was stabilized by overexpressed Herp mutants which were capable of binding to ubiquilins but were impaired in ER membrane targeting by deletion of the transmembrane domain. Our data suggest that Herp binding to ubiquilin proteins plays an important role in the ERAD pathway and that ubiquilins are specifically involved in degradation of only a subset of ubiquitinated targets, including Herp-dependent ERAD substrates

Effects of cellulose degradation products on the mobility of Eu(III) in repositories for low and intermediate level radioactive waste.

Science.gov (United States)

Diesen, Veronica; Forsberg, Kerstin; Jonsson, Mats

2017-10-15

The deep repository for low and intermediate level radioactive waste SFR in Sweden will contain large amounts of cellulosic waste materials contaminated with radionuclides. Over time the repository will be filled with water and alkaline conditions will prevail. In the present study degradation of cellulosic materials and the ability of cellulosic degradation products to solubilize and thereby mobilise Eu(III) under repository conditions has been investigated. Further, the possible immobilization of Eu(III) by sorption onto cement in the presence of degradation products has been investigated. The cellulosic material has been degraded under anaerobic and aerobic conditions in alkaline media (pH: 12.5) at ambient temperature. The degradation was followed by measuring the total organic carbon (TOC) content in the aqueous phase as a function of time. After 173days of degradation the TOC content is highest in the anaerobic artificial cement pore water (1547mg/L). The degradation products are capable of solubilising Eu(III) and the total europium concentration in the aqueous phase was 900μmol/L after 498h contact time under anaerobic conditions. Further it is shown that Eu(III) is adsorbed to the hydrated cement to a low extent (<9μmol Eu/g of cement) in the presence of degradation products. Copyright © 2017 Elsevier B.V. All rights reserved.

Reactive Membrane Barriers for Containment of Subsurface Contamination

Energy Technology Data Exchange (ETDEWEB)

William A. Arnold; Edward L. Cussler

2007-02-26

The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe{sup 0}) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents and cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe{sup 0} and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu{sup 2+}) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe{sup 0} barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a

Reactive Membrane Barriers for Containment of Subsurface Contamination

International Nuclear Information System (INIS)

William A. Arnold; Edward L. Cussler

2007-01-01

The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe 0 ) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents and cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe 0 and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu 2+ ) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe 0 barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a factor of three when

Plasma membrane profiling defines an expanded class of cell surface proteins selectively targeted for degradation by HCMV US2 in cooperation with UL141.

Directory of Open Access Journals (Sweden)

Jye-Lin Hsu

2015-04-01

Full Text Available Human cytomegalovirus (HCMV US2, US3, US6 and US11 act in concert to prevent immune recognition of virally infected cells by CD8+ T-lymphocytes through downregulation of MHC class I molecules (MHC-I. Here we show that US2 function goes far beyond MHC-I degradation. A systematic proteomic study using Plasma Membrane Profiling revealed US2 was unique in downregulating additional cellular targets, including: five distinct integrin α-chains, CD112, the interleukin-12 receptor, PTPRJ and thrombomodulin. US2 recruited the cellular E3 ligase TRC8 to direct the proteasomal degradation of all its targets, reminiscent of its degradation of MHC-I. Whereas integrin α-chains were selectively degraded, their integrin β1 binding partner accumulated in the ER. Consequently integrin signaling, cell adhesion and migration were strongly suppressed. US2 was necessary and sufficient for degradation of the majority of its substrates, but remarkably, the HCMV NK cell evasion function UL141 requisitioned US2 to enhance downregulation of the NK cell ligand CD112. UL141 retained CD112 in the ER from where US2 promoted its TRC8-dependent retrotranslocation and degradation. These findings redefine US2 as a multifunctional degradation hub which, through recruitment of the cellular E3 ligase TRC8, modulates diverse immune pathways involved in antigen presentation, NK cell activation, migration and coagulation; and highlight US2's impact on HCMV pathogenesis.

The product of the ABC half-transporter gene ABCG2 (BCRP/MXR/ABCP) is expressed in the plasma membrane

DEFF Research Database (Denmark)

Rocchi, E; Khodjakov, A; Volk, E L

2000-01-01

by Western blot and immunohistochemistry. This protein is highly overexpressed in several drug-resistant cell lines and localizes predominantly to the plasma membrane, instead of to intracellular membranes as seen with all other known half-transporters. Therefore, BCRP/MXR is unique among the ABC half......The products of the ABC gene family can be generally classified as either full-transporters of half-transporters. Full-transporters are expressed in the plasma membrane, whereas half-transporters are usually found in intracellular membranes. Recently, an ABC half-transporter, the ABCG2 gene product......-transporters by being localized to the plasma membrane....

A stability indicating HPLC method for determination of mebeverine in the presence of its degradation products and kinetic study of its degradation in oxidative condition.

Science.gov (United States)

Souri, E; Aghdami, A Negahban; Adib, N

2014-01-01

An HPLC method for determination of mebeverine hydrochloride (MH) in the presence of its degradation products was developed. The degradation of MH was studied under hydrolysis, oxidative and photolysis stress conditions. Under alkaline, acidic and oxidative conditions, degradation of MH was observed. The separation was performed using a Symmetry C18 column and a mixture of 50 mM KH2PO4, acetonitrile and tetrahydrfuran (THF) (63:35:2; v/v/v) as the mobile phase. No interference peaks from degradation products in acidic, alkaline and oxidative conditions were observed. The linearity, accuracy and precision of the method were studied. The method was linear over the range of 1-100 μg/ml MH (r(2)>0.999) and the CV values for intra-day and inter-day variations were in the range of 1.0-1.8%. The limit of quantification (LOQ) and the limit of detection (LOD) of the method were 1.0 and 0.2 μg/ml, respectively. Determination of MH in pharmaceutical dosage forms was performed using the developed method. Furthermore the kinetics of the degradation of MH in the presence of hydrogen peroxide was investigated. The proposed method could be a suitable method for routine quality control studies of mebeverine dosage forms.

Manipulation of host membranes by bacterial effectors.

Science.gov (United States)

Ham, Hyeilin; Sreelatha, Anju; Orth, Kim

2011-07-18

Bacterial pathogens interact with host membranes to trigger a wide range of cellular processes during the course of infection. These processes include alterations to the dynamics between the plasma membrane and the actin cytoskeleton, and subversion of the membrane-associated pathways involved in vesicle trafficking. Such changes facilitate the entry and replication of the pathogen, and prevent its phagocytosis and degradation. In this Review, we describe the manipulation of host membranes by numerous bacterial effectors that target phosphoinositide metabolism, GTPase signalling and autophagy.

Evaluation and Characterization of Membranes for HI/H2O/I2 Water Separation for the S-I Cycle

Energy Technology Data Exchange (ETDEWEB)

Frederick F. Stewart

2005-09-01

In the Sulfur-Iodine (S-I) thermochemical cycle, iodine is added to the product of the Bunsen reaction to facilitate the separation of sulfuric acid (H2SO4) from hydriodic acid (HI). The amount of iodine can be as high as 83% of the overall mass load of the Bunsen product stream, which potentially introduces a large burden on the cycle’s efficiency. Removal of water from the HI and I2 mixture would substantially reduce the amount of required additional iodine. In this work, Nafion® membranes have been studied for their use as de-watering membranes. Specifically, two thicknesses of Nafion membranes have been found to be effective in this application. The thicker membrane, Nafion-117®, produces moderate fluxes of water with very high separation factors. On the other hand, the thinner membrane, Nafion-112®, yielded very large fluxes of water, however with smaller separation factors. All membranes were found to be durable and did not degrade in contact with the feed stream over periods of time up to three months.

Genome comparison implies the role of Wsm2 in membrane trafficking and protein degradation

Directory of Open Access Journals (Sweden)

Guorong Zhang

2018-04-01

Wsm2 may combat WSMV disease through a molecular mechanism involving protein degradation and/or membrane trafficking. The 93 putative Wsm2 ancestor loci discovered in this study could serve as good candidates for future genetic isolation of the true Wsm2 locus.

High yield cell-free production of integral membrane proteins without refolding or detergents.

Science.gov (United States)

Wuu, Jessica J; Swartz, James R

2008-05-01

Integral membrane proteins act as critical cellular components and are important drug targets. However, difficulties in producing membrane proteins have hampered investigations of structure and function. In vivo production systems are often limited by cell toxicity, and previous in vitro approaches have required unnatural folding pathways using detergents or lipid solutions. To overcome these limitations, we present an improved cell-free expression system which produces high yields of integral membrane proteins without the use of detergents or refolding steps. Our cell-free reaction activates an Escherichia coli-derived cell extract for transcription and translation. Purified E. coli inner membrane vesicles supply membrane-bound components and the lipid environment required for insertion and folding. Using this system, we demonstrated successful synthesis of two complex integral membrane transporters, the tetracycline pump (TetA) and mannitol permease (MtlA), in yields of 570+/-50 microg/mL and 130+/-30 microg/mL of vesicle-associated protein, respectively. These yields are up to 400 times typical in vivo concentrations. Insertion and folding of these proteins are verified by sucrose flotation, protease digestion, and activity assays. Whereas TetA incorporates efficiently into vesicle membranes with over two-thirds of the synthesized protein being inserted, MtlA yields appear to be limited by insufficient concentrations of a membrane-associated chaperone.

Identification of Forced Degradation Products of Itopride by LC-PDA and LC-MS

OpenAIRE

Joshi, Payal; Bhoir, Suvarna; Bhagwat, A. M.; Vishwanath, K.; Jadhav, R. K.

2011-01-01

Degradation products of itopride formed under different forced conditions have been identified using LC-PDA and LC-MS techniques. Itopride was subjected to forced degradation under the conditions of hydrolysis, photolysis, oxidation, dry and wet heat, in accordance with the International Conference on Harmonization. The stress solutions were chromatographed on reversed phase C18 (250×4.6 mm, 5 μm) column with a mobile phase methanol:water (55:45, v/v) at a detection wavelength of 215 nm. Itop...

In-situ product removal from fermentations by membrane extraction: conceptual process design and economics

NARCIS (Netherlands)

Heerema, L.; Roelands, C.P.M.; Goetheer, E.L.V.; Verdoes, D.; Keurentjes, J.

2011-01-01

This paper describes a conceptual process design for the production of the model component phenol by a recombinant strain of the micro-organism Pseudomonas putida S12. The (bio)production of the inhibiting component phenol in a bioreactor is combined with direct product removal by membrane

Global sensitivity analysis for UNSATCHEM simulations of crop production with degraded waters

Science.gov (United States)

One strategy for maintaining irrigated agricultural productivity in the face of diminishing resource availability is to make greater use of marginal quality waters and lands. A key to sustaining systems using degraded irrigation waters is salinity management. Advanced simulation models and decision ...

HYDROLOGIC CONDITIONS AFFECTING THE TROPOSPHERIC FLUX OF VINCLOZOLIN AND ITS DEGRADATION PRODUCTS

Science.gov (United States)

A laboratory chamber was used to determine hydrologic conditions that lead to the tropospheric flux of a suspected anti-androgenic dicarboximide fungicide, vinclozolin (3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-oxzoli-dine-2,4-dione) and three degradation products from sterilized...

Isolation and characterization of a degradation product in leflunomide and a validated selective stability-indicating HPLC–UV method for their quantification

Directory of Open Access Journals (Sweden)

Balraj Saini

2015-06-01

Full Text Available Leflunomide (LLM is subjected to forced degradation under conditions of hydrolysis, oxidation, dry heat, and photolysis as recommended by International Conference on Harmonization guideline Q1A(R2. In total, four degradation products (I–IV were formed under different conditions. Products I, II and IV were formed in alkaline hydrolytic, acidic hydrolytic and alkaline photolytic conditions. LLM and all degradation products were optimally resolved by gradient elution over a C18 column. The major degradation product (IV formed in hydrolytic alkaline conditions was isolated through column chromatography. Based on its 1H NMR, IR and mass spectral data, it was characterized as a British Pharmacopoeial impurity B. The HPLC method was found to be linear, accurate, precise, sensitive, specific, rugged and robust for quantification of LLM as well as product IV. Finally, the method was applied to stability testing of the commercially available LLM tablets. Keywords: Leflunomide, Characterization, Forced degradation, Degradation product, HPLC–UV

A New Platform for Profiling Degradation-Related Impurities Via Exploiting the Opportunities Offered by Ion-Selective Electrodes: Determination of Both Diatrizoate Sodium and Its Cytotoxic Degradation Product.

Science.gov (United States)

Riad, Safaa M; Abd El-Rahman, Mohamed K; Fawaz, Esraa M; Shehata, Mostafa A

2018-05-01

Although the ultimate goal of administering active pharmaceutical ingredients (APIs) is to save countless lives, the presence of impurities and/or degradation products in APIs or formulations may cause harmful physiological effects. Today, impurity profiling (i.e., the identity as well as the quantity of impurity in a pharmaceutical) is receiving critical attention from regulatory authorities. Despite the predominant use of spectroscopic and chromatographic methods over electrochemical methods for impurity profiling of APIs, this work investigates the opportunities offered by electroanalytical methods, particularly, ion-selective electrodes (ISEs), for profiling degradation-related impurities (DRIs) compared with conventional spectroscopic and chromatographic methods. For a meaningful comparison, diatrizoate sodium (DTA) was chosen as the anionic X-ray contrast agent based on its susceptibility to deacetylation into its cytotoxic and mutagenic degradation product, 3,5-diamino-2,4,6 triiodobenzoic acid (DTB). This cationic diamino compound can be also detected as an impurity in the final product because it is used as a synthetic precursor for the synthesis of DTA. In this study, four novel sensitive and selective sensors for the determination of both DTA and its cytotoxic degradation products are presented. Sensors I and II were developed for the determination of the anionic drug, DTA, and sensors III and IV were developed for the determination of the cationic cytotoxic impurity. The use of these novel sensors not only provides a stability-indicating method for the selective determination of DTA in the presence of its degradation product, but also permits DRI profiling. Moreover, a great advantage of these proposed ISE systems is their higher sensitivity for the quantification of DTB relative to other spectroscopic and chromatographic methods, so it can measure trace amounts of DTB impurities in DTA bulk powder and pharmaceutical formulation without a need for

Application of Microextraction Techniques Including SPME and MESI to the Thermal Degradation of Polymers: A Review.

Science.gov (United States)

Kaykhaii, Massoud; Linford, Matthew R

2017-03-04

Here, we discuss the newly developed micro and solventless sample preparation techniques SPME (Solid Phase Microextraction) and MESI (Membrane Extraction with a Sorbent Interface) as applied to the qualitative and quantitative analysis of thermal oxidative degradation products of polymers and their stabilizers. The coupling of these systems to analytical instruments is also described. Our comprehensive literature search revealed that there is no previously published review article on this topic. It is shown that these extraction techniques are valuable sample preparation tools for identifying complex series of degradation products in polymers. In general, the number of products identified by traditional headspace (HS-GC-MS) is much lower than with SPME-GC-MS. MESI is particularly well suited for the detection of non-polar compounds, therefore number of products identified by this technique is not also to the same degree of SPME. Its main advantage, however, is its ability of (semi-) continuous monitoring, but it is more expensive and not yet commercialized.

Production efficiency of micellar casein concentrate using polymeric spiral-wound microfiltration membranes.

Science.gov (United States)

Beckman, S L; Zulewska, J; Newbold, M; Barbano, D M

2010-10-01

Most current research has focused on using ceramic microfiltration (MF) membranes for micellar casein concentrate production, but little research has focused on the use of polymeric spiral-wound (SW) MF membranes. A method for the production of a serum protein (SP)-reduced micellar casein concentrate using SW MF was compared with a ceramic MF membrane. Pasteurized (79°C, 18s) skim milk (1,100 kg) was microfiltered at 50°C [about 3 × concentration] using a 0.3-μm polyvinylidene fluoride spiral-wound membrane, bleed-and-feed, 3-stage process, using 2 diafiltration stages, where the retentate was diluted 1:2 with reverse osmosis water. Skim milk, permeate, and retentate were analyzed for SP content, and the reduction of SP from skim milk was determined. Theoretically, 68% of the SP content of skim milk can be removed using a single-stage 3× MF. If 2 subsequent water diafiltration stages are used, an additional 22% and 7% of the SP can be removed, respectively, giving a total SP removal of 97%. Removal of SP greater than 95% has been achieved using a 0.1-μm pore size ceramic uniform transmembrane pressure (UTP) MF membrane after a 3-stage MF with diafiltration process. One stage of MF plus 2 stages of diafiltration of 50°C skim milk using a polyvinylidene fluoride polymeric SW 0.3-μm membrane yielded a total SP reduction of only 70.3% (stages 1, 2, and 3: 38.6, 20.8, and 10.9%, respectively). The SP removal rate for the polymeric SW MF membrane was lower in all 3 stages of processing (stages 1, 2, and 3: 0.05, 0.04, and 0.03 kg/m(2) per hour, respectively) than that of the comparable ceramic UTP MF membrane (stages 1, 2, and 3: 0.30, 0.11, and 0.06 kg/m(2) per hour, respectively), indicating that SW MF is less efficient at removing SP from 50°C skim milk than the ceramic UTP system. To estimate the number of steps required for the SW system to reach 95% SP removal, the third-stage SP removal rate (27.4% of the starting material SP content) was used to

Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells.

Science.gov (United States)

Yamauchi, Noboru; Gosho, Tadashi; Asatuma, Satoru; Toyooka, Kiminori; Fujiwara, Toru; Matsuoka, Ken

2013-01-01

In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP) in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM). This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species.

Butanol production from concentrated lactose/whey permeate: Use of pervaporation membrane to recover and concentrate product

Science.gov (United States)

In these studies butanol (acetone butanol ethanol, or ABE) was produced from concentrated lactose/whey permeate containing 211 gL-1 lactose. Fermentation of such a highly concentrated lactose solution was possible due to simultaneous product removal using a pervaporation membrane. In this system a p...

The Use of Membranes Prepared by Radiation - Induced Grafting in Waste Water Treatment

International Nuclear Information System (INIS)

El-Arnaouty, M.B.; Abdel Aal, S.E.; Dessouki, A.M.

2000-01-01

Membranes were prepared by the radiation-induced grafting of N-vinylpyrrolidone onto low density polyethylene and the possibility for their practical use in the removal of two dyes: Acid red 116(Erionyl red 2B) and blue reactive (Brilliant bright blue) was studied. The effect of the degree of grafting on the adsorption of these pollutants was investigated and showed maximum adsorption occurred at 394 % grafting. Radiation degradation of the dyes with a dose of ∼ 5 KGy was followed by adsorption of the residual concentration of the dyes by the membranes, which resulted in the complete removal of these pollutants as well as the radiolysis products present in the irradiated solutions. Also, characterization of the membranes before and after adsorption was carried out using thermogravimetric analysis and scanning electron microscopy

Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration

Directory of Open Access Journals (Sweden)

Mehrdad Ebrahimi

2015-12-01

Full Text Available Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD and remove residual lignin from the effluent flow during sulfite pulp production. A comparison of the ceramic membranes in terms of separation efficiency and performance revealed that the two-stage process configuration with microfiltration followed by ultrafiltration was most suitable for the efficient treatment of the alkaline bleaching effluent tested herein, reducing the COD concentration and residual lignin levels by more than 35% and 70%, respectively.

Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration.

Science.gov (United States)

Ebrahimi, Mehrdad; Busse, Nadine; Kerker, Steffen; Schmitz, Oliver; Hilpert, Markus; Czermak, Peter

2015-12-31

Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD) and remove residual lignin from the effluent flow during sulfite pulp production. A comparison of the ceramic membranes in terms of separation efficiency and performance revealed that the two-stage process configuration with microfiltration followed by ultrafiltration was most suitable for the efficient treatment of the alkaline bleaching effluent tested herein, reducing the COD concentration and residual lignin levels by more than 35% and 70%, respectively.

Efficient photocatalytic degradation of gaseous N,N-dimethylformamide in tannery waste gas using doubly open-ended Ag/TiO2 nanotube array membranes

Science.gov (United States)

Zhao, Yang; Ma, Lin; Chang, Wenkai; Huang, Zhiding; Feng, Xugen; Qi, Xiaoxia; Li, Zenghe

2018-06-01

Gaseous N,N-dimethylformamide (DMF), typical volatile organic compound exhausted from manufacturing factories, may damage the health of workers under long-term exposure even at low levels. The defined geometry, porous surface and highly ordered channels make the free-standing anodic TiO2 nanotube (TiNT) arrays particularly suitable for applications of practical air purification by flow-through photocatalysis. In the present work, crystallized doubly open-ended Ag/TiNT array membranes were designed and prepared by employing a lift-off process based on an anodization-annealing-anodization-etching sequence, followed by uniform Ag nanoparticles decoration. For the photocatalytic degradation of gaseous DMF at low concentration levels close to that found in realistic pollutant air, an analytical methodology for the monitoring and determination of degradation process was developed based on the coupling of headspace sampling with gas chromatography mass spectrometry (HS-GC-MS). The doubly open-ended Ag/TiNT arrays exhibited higher removal efficiency of gaseous DMF from air compared with conventional bottom-closed Ag/TiNT arrays and pure bottomless TiNT arrays. These results indicated that the photocatalytic properties of TiNT arrays were improved with the open-bottom morphology and the Ag nanoparticles decoration. Based on the analysis with GC-MS and high performance ion chromatography (HPIC), it was found that demethylation is the main pathway of DMF degradation in photocatalytic reactions. Furthermore, decontamination of actual polluted tannery waste gas collected in leather factory proved that the photocatalysis on doubly open-ended Ag/TiNT array membrane is an efficient way and a promising application to treat air contaminated by DMF despite the complexity of various volatile organic compounds.

Toxicity of tetracyclines and tetracycline degradation products to environmentally relevant bacteria, including selected tetracycline-resistant bacteria

DEFF Research Database (Denmark)

Halling-Sørensen, B.; Sengeløv, G.; Tjørnelund, J.

2002-01-01

Tetracyclines used in veterinary therapy invariably will find their way as parent compound and degradation products to the agricultural field. Major degradation products formed due to the limited stability of parent tetracyclines (tetracycline, chlortetracycline, and oxytetracycline) in aqueous...... at the same concentration level as tetracycline, chlortetracycline, and oxytetracycline on both the sludge and the tetracycline-sensitive soil bacteria. Further, both 5a,6-anhydrotetracychne and 5a,6-anhydrochlortetracycline had potency on tetracycline-resistant bacteria supporting a mode of action different...

Design of flexible polyphenylene proton-conducting membrane for next-generation fuel cells.

Science.gov (United States)

Miyake, Junpei; Taki, Ryunosuke; Mochizuki, Takashi; Shimizu, Ryo; Akiyama, Ryo; Uchida, Makoto; Miyatake, Kenji

2017-10-01

Proton exchange membrane fuel cells (PEMFCs) are promising devices for clean power generation in automotive, stationary, and portable applications. Perfluorosulfonic acid (PFSA) ionomers (for example, Nafion) have been the benchmark PEMs; however, several problems, including high gas permeability, low thermal stability, high production cost, and environmental incompatibility, limit the widespread dissemination of PEMFCs. It is believed that fluorine-free PEMs can potentially address all of these issues; however, none of these membranes have simultaneously met the criteria for both high performance (for example, proton conductivity) and durability (for example, mechanical and chemical stability). We present a polyphenylene-based PEM (SPP-QP) that fulfills the required properties for fuel cell applications. The newly designed PEM exhibits very high proton conductivity, excellent membrane flexibility, low gas permeability, and extremely high stability, with negligible degradation even under accelerated degradation conditions, which has never been achieved with existing fluorine-free PEMs. The polyphenylene PEM also exhibits reasonably high fuel cell performance, with excellent durability under practical conditions. This new PEM extends the limits of existing fluorine-free proton-conductive materials and will help to realize the next generation of PEMFCs via cost reduction as well as the performance improvement compared to the present PFSA-based PEMFC systems.

Review of Supported Pd-Based Membranes Preparation by Electroless Plating for Ultra-Pure Hydrogen Production.

Science.gov (United States)

Alique, David; Martinez-Diaz, David; Sanz, Raul; Calles, Jose A

2018-01-23

In the last years, hydrogen has been considered as a promising energy vector for the oncoming modification of the current energy sector, mainly based on fossil fuels. Hydrogen can be produced from water with no significant pollutant emissions but in the nearest future its production from different hydrocarbon raw materials by thermochemical processes seems to be more feasible. In any case, a mixture of gaseous compounds containing hydrogen is produced, so a further purification step is needed to purify the hydrogen up to required levels accordingly to the final application, i.e., PEM fuel cells. In this mean, membrane technology is one of the available separation options, providing an efficient solution at reasonable cost. Particularly, dense palladium-based membranes have been proposed as an ideal chance in hydrogen purification due to the nearly complete hydrogen selectivity (ideally 100%), high thermal stability and mechanical resistance. Moreover, these membranes can be used in a membrane reactor, offering the possibility to combine both the chemical reaction for hydrogen production and the purification step in a unique device. There are many papers in the literature regarding the preparation of Pd-based membranes, trying to improve the properties of these materials in terms of permeability, thermal and mechanical resistance, poisoning and cost-efficiency. In this review, the most relevant advances in the preparation of supported Pd-based membranes for hydrogen production in recent years are presented. The work is mainly focused in the incorporation of the hydrogen selective layer (palladium or palladium-based alloy) by the electroless plating, since it is one of the most promising alternatives for a real industrial application of these membranes. The information is organized in different sections including: (i) a general introduction; (ii) raw commercial and modified membrane supports; (iii) metal deposition insights by electroless-plating; (iv) trends in

Development of membrane technology for production of concentrated fertilizer and clean water

DEFF Research Database (Denmark)

Camilleri Rumbau, Maria Salud

The global increasing livestock production is reflected in a high rate of animal waste production, commonly known as manure or animal slurry. These effluents are rich in nutrients such as nitrogen, phosphorus and potassium. Solid-liquid separation of farm effluents is a common practice...... for obtaining a phosphorus-rich fraction and a liquid fraction rich in nitrogen and potassium. However, the nutrient concentration in the obtained liquid fractions remains unbalanced due to the high water content. Membrane technologies have previously proved to be a suitable technology for separation....... During FO processing of digestate liquid fractions, membranes were able to retain ammonia nitrogen -TAN while using a highly saline wastewater from a tannery beam house. A salt rejection higher than 90% was achieved along the experiments. However, when acidification of the feed digestate liquid fraction...

Source of fibrin/fibrinogen degradation products in the CSF after subarachnoid hemorrhage

NARCIS (Netherlands)

Vermeulen, M.; van Vliet, H. H.; Lindsay, K. W.; Hijdra, A.; van Gijn, J.

1985-01-01

In 48 patients with a subarachnoid hemorrhage, levels of fibrin/fibrinogen degradation products (FDP's), total protein, and plasminogen were measured in the cerebrospinal fluid (CSF) between Days 9 and 15 after the bleed. Of these 48 patients, 22 received tranexamic acid. Despite a significant

Reforming and filtration Dual membrane for the production of hydrogen by cracking reaction

International Nuclear Information System (INIS)

Hafsaoui, J.

2009-02-01

In a context of rarefaction and increasing of prices of fossil energetic resources, it is necessary to diversify the energetic offer. Hydrogen seems to be one of the most promising vectors, although technological matters associated to its production slow down its development. In this context, the present work aims at elaborating a system able to produce pure hydrogen from hydrocarbon, and in particularly from methane. It is constituted of three membranes, which specific roles are reforming, separation and restitution of molecular hydrogen. The first membrane is porous and is made of a cermet BaCe 0.85 Y 0.15 O 3-α / nickel. The second one is dense and is elaborated either simply from BaCe 0.85 Y 0.15 O 3-α , or from the same cermet as the first membrane, depending whether the system operates in a galvanic or in a non-galvanic mode. The last one is of the same nature and morphology as the first one. The three membranes are fabricated and coupled one with the others by the process called co-tape-casting in organic solvent followed by a step of co-sintering. Hydrogen enters then in the porosity of the first membrane where it is oxidized when meeting with triple phases boundaries. In a non-galvanic system, protons and electrons can go through the second membrane, following the percolating proton and ion conducting paths, to reach the third membrane. In a galvanic system, electrons are transported toward the third membrane via an external circuit, which imposes a voltage. At the third membrane triple phase boundaries, electrons and protons recombine to form pure molecular hydrogen. These two systems galvanic and non galvanic have been designed and fabricated, and the motivation that has led to the choice of the materials used was given at each step of the process. Thanks to the comprehension of the different phenomena taking place during operating conditions, a rather optimized process leading to a system of production and purification of hydrogen was realized

Metal complexation in near field conditions of nuclear waste repository - stability constant of copper complexation with cellulose degradation products, in alkaline conditions

International Nuclear Information System (INIS)

Guede, Kipre Bertin

2005-11-01

Copper is a stable element and spent fuel component which constitutes the radioactive waste. The reaction of Copper with cellulose degradation products in alkaline conditions was performed to mimic what occurs in near field conditions of nuclear waste repository. From the characteristics of Cu (II), this thesis aims at inferring the behaviour of radionuclides vis a vis the degradation products of cellulose. The contribution of the present work is therefore the assessment of the stability of the major cellulose degradation product, its affinity for Copper and the extent of the complexation function 13 between Cu (II) and the organic moieties. The formation of cellulose degradation products was followed by measurement of p11, Conductivity, Angle of rotation, relative abundance of aliphatics and aromatics (E4/E6 ) aid by UV-visible spectroscopy. The TOC was determined using the Walkley and Black titration after respectively 31 weeks and 13 weeks of degradation for the reaction mixtures T and A, N. The stability of the major degradation products gave the following figures: ISA(A): - 13 43.39 <ΔG -10639.88 ISA(N): - Ii 436.45<ΔG< -9103.6. The study of the characteristics of Gluconic Acid, as a model compound, was carried out in an attempt to give a general picture of the roper ties of cellulose degradation products. The Complexation between Cu (II) and the organic ligand (Cellulose degradation products) was performed using UV-visible spectroscopy and Ion Distribution technique. The Log B value obtained from the complexation studies at 336 nm for 1 = 0. I Ni NaClO4 and I = 0.01 M NaClO4, falls within a range of 3.48 to 3.74 for the standard reference material (Gluconic Acid), and within I .87 to 2.3 I, and I .6 to 2.01, respectively for the degradation Products ISA (A) and ISA(N). The ion distribution studies showed that: • In (he absence of the degradation product ISA and at pH = 3.68. 56. 17 % of Cu (II) was bound to the resin. • In the presence of ISA and at 2

Podocytes degrade endocytosed albumin primarily in lysosomes.

Science.gov (United States)

Carson, John M; Okamura, Kayo; Wakashin, Hidefumi; McFann, Kim; Dobrinskikh, Evgenia; Kopp, Jeffrey B; Blaine, Judith

2014-01-01

Albuminuria is a strong, independent predictor of chronic kidney disease progression. We hypothesize that podocyte processing of albumin via the lysosome may be an important determinant of podocyte injury and loss. A human urine derived podocyte-like epithelial cell (HUPEC) line was used for in vitro experiments. Albumin uptake was quantified by Western blot after loading HUPECs with fluorescein-labeled (FITC) albumin. Co-localization of albumin with lysosomes was determined by confocal microscopy. Albumin degradation was measured by quantifying FITC-albumin abundance in HUPEC lysates by Western blot. Degradation experiments were repeated using HUPECs treated with chloroquine, a lysosome inhibitor, or MG-132, a proteasome inhibitor. Lysosome activity was measured by fluorescence recovery after photo bleaching (FRAP). Cytokine production was measured by ELISA. Cell death was determined by trypan blue staining. In vivo, staining with lysosome-associated membrane protein-1 (LAMP-1) was performed on tissue from a Denys-Drash trangenic mouse model of nephrotic syndrome. HUPECs endocytosed albumin, which co-localized with lysosomes. Choloroquine, but not MG-132, inhibited albumin degradation, indicating that degradation occurs in lysosomes. Cathepsin B activity, measured by FRAP, significantly decreased in HUPECs exposed to albumin (12.5% of activity in controls) and chloroquine (12.8%), and declined further with exposure to albumin plus chloroquine (8.2%, plysosomes are involved in the processing of endocytosed albumin in podocytes, and lysosomal dysfunction may contribute to podocyte injury and glomerulosclerosis in albuminuric diseases. Modifiers of lysosomal activity may have therapeutic potential in slowing the progression of glomerulosclerosis by enhancing the ability of podocytes to process and degrade albumin.

Study on methane separation from steam reforming product gas with polyimide membrane

International Nuclear Information System (INIS)

Koiso, Hiroshi; Inagaki, Yoshiyuki; Aita, Hideki; Sekita, Kenji; Haga, Katsuhiro; Hino, Ryutaro.

1997-10-01

In the HTTR hydrogen production system by steam reforming of natural gas (main component: CH 4 ), CH 4 conversion rate is limited to approximately 65% due to high pressure and low temperature conditions (4.5 MPa, 800degC). The one of the measures to improve CH 4 conversion is recycling of residual CH 4 extracted from steam reforming product gas with a gas separator. Experimental and analytical studies on CH 4 separation from gas mixture composed of CH 4 , H 2 , CO 2 and CO were carried out to investigate gas separation characteristics of a polyimide membrane gas separator. Measured permeability of each gas in gas mixture was reduced from 1/3 to 1/14 of that obtained with a single gas (catalog value). The polyimide membrane could extracted CH 4 of approximately 80% from gas mixture, then, H 2 and CO 2 more than 98% were removed. It was confirmed that the polyimide membrane could be available to residual CH 4 recycling. The analytical results by a difference method gave good prospects of experimental results such as permeated flow rate, mol-fraction profiles and so on. Therefore, it can be said the analysis method was established. (author)

Lipid Droplet Formation Is Dispensable for Endoplasmic Reticulum-associated Degradation*

Science.gov (United States)

Olzmann, James A.; Kopito, Ron R.

2011-01-01

Proteins that fail to fold or assemble in the endoplasmic reticulum (ER) are destroyed by cytoplasmic proteasomes through a process known as ER-associated degradation. Substrates of this pathway are initially sequestered within the ER lumen and must therefore be dislocated across the ER membrane to be degraded. It has been proposed that generation of bicellar structures during lipid droplet formation may provide an “escape hatch” through which misfolded proteins, toxins, and viruses can exit the ER. We have directly tested this hypothesis by exploiting yeast strains defective in lipid droplet formation. Our data demonstrate that lipid droplet formation is dispensable for the dislocation of a plant toxin and the degradation of both soluble and integral membrane glycoproteins. PMID:21693705

Investigation of forced and total degradation products of amlodipine besylate by liquid chromatography and liquid chromatography-mass spectrometry

Directory of Open Access Journals (Sweden)

Stoiljković Zora Ž.

2014-01-01

Full Text Available An isocratic, reversed-phase liquid chromatographic method was applied for the investigation of the degradation products of amlodipine besylate under the stressed conditions in solution. Amlodipine besylate stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation and photodegradation as well as to the electrochemical degradation by cyclic voltammetry in 0.05 mol/L NaHCO3 on gold electrode. The total degradation of amlodipine besylate was achieved in 5 mol/L NaOH at 80°C for 6 h and the compound with molecular formula C15H16NOCl was identified as a main degradation product. Under acidic (5 mol/L HCl at 80°C for 6 h stress conditions 75.2% of amlodipine besylate degradation was recorded. Oxidative degradation in the solution of 3% H2O2-methanol 80:20 at 80°C for 6 h showed that amlodipine besylate degraded to 80.1%. After 14 days of expose in photostability chamber amlodipine besylate solution showed degradation of 32.2%. In electrochemical degradation after 9 hours of cyclization the beginning of amlodipine oxidation was shifted for 200 mV to more negative potentials, with the degradation of 66.5%. Mass spectrometry analysis confirmed the presence of dehydro amlodipine derivate with molecular formula C20H23N2O5Cl in oxidative and acidic conditions while in electrochemical degradation was detected in traces. [Projekat Ministarsva nauke Republike Srbije, br. 172013

Open circuit voltage durability study and model of catalyst coated membranes at different humidification levels

Energy Technology Data Exchange (ETDEWEB)

Kundu, Sumit; Fowler, Michael W.; Simon, Leonardo C. [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario (Canada); Abouatallah, Rami; Beydokhti, Natasha [Hydrogenics Corporation, 5985 McLaughlin Road, Mississauga, Ontario (Canada)

2010-11-01

Fuel cell material durability is an area of extensive research today. Chemical degradation of the ionomer membrane is one important degradation mechanism leading to overall failure of fuel cells. This study examined the effects of relative humidity on the chemical degradation of the membrane during open circuit voltage testing. Five Gore trademark PRIMEA {sup registered} series 5510 catalyst coated membranes were degraded at 100%, 75%, 50%, and 20% RH. Open circuit potential and cumulative fluoride release were monitored over time. Additionally scanning electron microscopy images were taken at end of the test. The results showed that with decreasing RH fluoride release rate increased as did performance degradation. This was attributed to an increase in gas crossover with a decrease in RH. Further, it is also shown that interruptions in testing may heavily influence cumulative fluoride release measurements where frequent stoppages in testing will cause fluoride release to be underestimated. SEM analysis shows that degradation occurred in the ionomer layer close to the cathode catalyst. A chemical degradation model of the ionomer membrane was used to model the results. The model was able to predict fluoride release trends, including the effects of interruptions, showing that changes in gas crossover with RH could explain the experimental results. (author)

Limited and selective transfer of plasma membrane glycoproteins to membrane of secondary lysosomes

International Nuclear Information System (INIS)

Haylett, T.; Thilo, L.

1986-01-01

Radioactive galactose, covalently bound to cell surface glycoconjugates on mouse macrophage cells, P388D 1 , was used as a membrane marker to study the composition, and the kinetics of exchange, of plasma membrane-derived constituents in the membrane of secondary lysosomes. Secondary lysosomes were separated from endosomes and plasma membrane by self-forming Percoll density gradients. Horseradish peroxidase, taken up by fluid-phase pinocytosis, served as a vesicle contents marker to monitor transfer of endosomal contents into secondary lysosomes. Concurrently, the fraction of plasma membrane-derived label of secondary lysosomes increased by first order kinetics from 4 PAGE, labeled molecules of M/sub r/ 160-190 kD were depleted and of the M/sub r/ 100-120 kD were enriched in lysosome membrane compared with the relative composition of label on the cell surface. No corresponding selectivity was observed for the degradation of label, with all M/sub r/ classes being affected to the same relative extent. The results indicate that endocytosis-derived transfer of plasma membrane constitutents to secondary lysosomes is a limited and selective process, and that only ∼1% of internalized membrane is recycled via a membrane pool of secondary lysosomes

REVERSE OSMOSIS CONCENTRATION OF ORANGE JUICE USING SPIRAL WOUND MEMBRANES

Directory of Open Access Journals (Sweden)

W. A. de ARAUJO

2009-03-01

Full Text Available

Flavor and odor components of foods are often lost during processing which leads to a poorer quality final product compared with the fresh ingredients. The orange juice industry concentrates juice (45-66ºBrix in TASTE (Thermally Accelerated Short Time Evaporator to remove excess water, and thus reduce storage and transportation costs, but also to improve product stability. Evaporation results in a loss of fresh juice flavors, color degradation and “cooked” taste due to the thermal effects. Methods using less heat for thermal damage reduction must be investigated to establish parameters for future commercial processes. The promising alternative is Reverse Osmosis (RO, but it cannot achieve concentrations greater than 30ºBrix. RO has advantages over traditional evaporation techniques in removing water. Because less heat is used, thermal damage to products is generally eliminated. In this project tests were performed using unpasteurised Single Strength Orange Juice (SSOJ, spiral wound membranes (Polyamide, and a DESAL pilot system model 4040. The aim was to evaluate spiral wound membranes on the basis of flux as a function of time. Retentate concentrations were 15-20ºBrix, and GC-FID analyses were used in order to understand aroma losses. KEYWORDS: Orange; juice; membrane; concentration; osmosis; reverse.

Stimulated-healing of proton exchange membrane fuel cell catalyst

NARCIS (Netherlands)

Latsuzbaia, R.; Negro, E.; Koper, G.J.M.

2013-01-01

Platinum nanoparticles, which are used as catalysts in Proton Exchange Membrane Fuel Cells (PEMFC), tend to degrade after long-term operation. We discriminate the following mechanisms of the degradation: poisoning, migration and coalescence, dissolution, and electrochemical Ostwald ripening. There

Ethanol production in a membrane bioreactor: pilot-scale trials in a corn wet mill.

Science.gov (United States)

Escobar, J M; Rane, K D; Cheryan, M

2001-01-01

Pilot plant trials were conducted in a corn wet mill with a 7000-L membrane recycle bioreactor (MRB) that integrated ceramic microfiltration membranes in a semi-closed loop configuration with a stirred-tank reactor. Residence times of 7.5-10 h with ethanol outputs of 10-11.5% (v/v) were obtained when the cell concentration was 60-100 g/L dry wt of yeast, equivalent to about 10(9)-10(10) cells/mL. The performance of the membrane was dependent on the startup mode and pressure management techniques. A steady flux of 70 L/(m2 x h) could be maintained for several days before cleaning was necessary. The benefits of the MRB include better productivity; a clear product stream containing no particulates or yeast cells, which should improve subsequent stripping and distillation operations; and substantially reduced stillage handling. The capital cost of the MRB is $21-$34/(m3 x yr) ($0.08-$0.13/[gal x yr]) of ethanol capacity. Operating cost, including depreciation, energy, membrane replacement, maintenance, labor, and cleaning, is $4.5-9/m3 ($0.017-$0.034/gal) of ethanol.

Fouling characteristics and cleaning strategies of NF membranes for the advanced treatment of antibiotic production wastewater.

Science.gov (United States)

Wang, Jianxing; Li, Kun; Yu, Dawei; Zhang, Junya; Wei, Yuansong

2017-04-01

The nanofiltration (NF) membrane fouling characteristics and cleaning strategies were investigated through a laboratory-scale NF fouling test treating membrane bioreactor (MBR) effluent and MBR-granular activated carbon (GAC) effluent of an antibiotic production wastewater by DK and NF90 membranes, respectively. Results showed that organic fouling is the main NF membrane fouling for treating both the MBR effluent and MBR-GAC effluent. Soluble microbial by-product (SMP)-like and aromatic protein-like substances were the dominant components in the foulants, whereas humic-like substances had little contribution to the NF fouling. The fouling of DK was more severe than that of NF90. However, foulants respond by UV 254 were more easily to foul NF90 membrane. It could get satisfactory effect using combined cleaning of acid (HCl, pH 2.0∼2.5) and alkali (NaOH + 0.3 wt% NaDS, pH 10.0∼10.5). The favorable cleaning strategy is "acid + alkali" for treating MBR-GAC effluent, while it is "alkali + acid" for treating MBR effluent.

Functionalized PCL/HA nanocomposites as microporous membranes for bone regeneration

Energy Technology Data Exchange (ETDEWEB)

Basile, Maria Assunta; Gomez d' Ayala, Giovanna; Malinconico, Mario [Institute for Polymers, Composites and Biomaterials, CNR, Via Campi Flegrei 34, Pozzuoli (Naples) (Italy); Laurienzo, Paola, E-mail: paola.laurienzo@ipcb.cnr.it [Institute for Polymers, Composites and Biomaterials, CNR, Via Campi Flegrei 34, Pozzuoli (Naples) (Italy); Coudane, Jean; Nottelet, Benjamin [Institut des Biomolécules Max Mousseron (IBMM), Artificial Biopolymers Group, CNRS UMR 5247, University of Montpellier 1, Faculty of Pharmacy, 15 Av. C. Flahault, Montpellier 34093 (France); Ragione, Fulvio Della [Department of Biochemistry and Biophysics, Second University of Naples, Via L. De Crecchio 7, Naples (Italy); Oliva, Adriana, E-mail: adriana.oliva@unina2.it [Department of Biochemistry and Biophysics, Second University of Naples, Via L. De Crecchio 7, Naples (Italy)

2015-03-01

In the present work, microporous membranes based on poly(ε-caprolactone) (PCL) and PCL functionalized with amine (PCL-DMAEA) or anhydride groups (PCL-MAGMA) were realized by solvent–non solvent phase inversion and proposed for use in Guided Tissue Regeneration (GTR). Nanowhiskers of hydroxyapatite (HA) were also incorporated in the polymer matrix to realize nanocomposite membranes. Scanning Electron Microscopy (SEM) showed improved interfacial adhesion with HA for functionalized polymers, and highlighted substantial differences in the porosity. A relationship between the developed porous structure of the membrane and the chemical nature of grafted groups was proposed. Compared to virgin PCL, hydrophilicity increases for functionalized PCL, while the addition of HA influences significantly the hydrophilic characteristics only in the case of virgin polymer. A significant increase of in vitro degradation rate was found for PCL-MAGMA based membranes, and at lower extent of PCL-DMAEA membranes. The novel materials were investigated regarding their potential as support for cell growth in bone repair using multipotent mesenchymal stromal cells (MSC) as a model. MSC plated onto the various membranes were analyzed in terms of adhesion, proliferation and osteogenic capacity that resulted to be related to chemical as well as porous structure. In particular, PCL-DMAEA and the relative nanocomposite membranes are the most promising in terms of cell-biomaterial interactions. - Graphical abstract: Functionalized PCL is used to realize nanocomposites with hydroxyapatite (HA) in the form of microporous membranes. The influence of different grafted groups on mechanical properties, in vitro degradation, porous membrane structure and interaction with mesenchymal stromal cells (MSC) is discussed. - Highlights: • Functionalized PCL shows faster in vitro degradation rate. • Functionalized PCL shows superior cell adhesion, proliferation and differentiation. • Nanocomposites based

Functionalized PCL/HA nanocomposites as microporous membranes for bone regeneration

International Nuclear Information System (INIS)

Basile, Maria Assunta; Gomez d'Ayala, Giovanna; Malinconico, Mario; Laurienzo, Paola; Coudane, Jean; Nottelet, Benjamin; Ragione, Fulvio Della; Oliva, Adriana

2015-01-01

In the present work, microporous membranes based on poly(ε-caprolactone) (PCL) and PCL functionalized with amine (PCL-DMAEA) or anhydride groups (PCL-MAGMA) were realized by solvent–non solvent phase inversion and proposed for use in Guided Tissue Regeneration (GTR). Nanowhiskers of hydroxyapatite (HA) were also incorporated in the polymer matrix to realize nanocomposite membranes. Scanning Electron Microscopy (SEM) showed improved interfacial adhesion with HA for functionalized polymers, and highlighted substantial differences in the porosity. A relationship between the developed porous structure of the membrane and the chemical nature of grafted groups was proposed. Compared to virgin PCL, hydrophilicity increases for functionalized PCL, while the addition of HA influences significantly the hydrophilic characteristics only in the case of virgin polymer. A significant increase of in vitro degradation rate was found for PCL-MAGMA based membranes, and at lower extent of PCL-DMAEA membranes. The novel materials were investigated regarding their potential as support for cell growth in bone repair using multipotent mesenchymal stromal cells (MSC) as a model. MSC plated onto the various membranes were analyzed in terms of adhesion, proliferation and osteogenic capacity that resulted to be related to chemical as well as porous structure. In particular, PCL-DMAEA and the relative nanocomposite membranes are the most promising in terms of cell-biomaterial interactions. - Graphical abstract: Functionalized PCL is used to realize nanocomposites with hydroxyapatite (HA) in the form of microporous membranes. The influence of different grafted groups on mechanical properties, in vitro degradation, porous membrane structure and interaction with mesenchymal stromal cells (MSC) is discussed. - Highlights: • Functionalized PCL shows faster in vitro degradation rate. • Functionalized PCL shows superior cell adhesion, proliferation and differentiation. • Nanocomposites based

Enzymatic degradation of plutonium-contaminated cellulose products

International Nuclear Information System (INIS)

Heintz, C.E.; Rainwater, K.A.; Swift, L.M.; Barnes, D.L.; Worl, L.; Avens, L.

1999-01-01

Enzyme solutions produced for commercial purposes unrelated to waste management have the potential for reducing the volume of wastes in streams containing cellulose, lipid and protein materials. For example, the authors have shown that cellulases used in denim production and in detergent formulations are able to digest cellulose-containing sorbents and other cellulose-based wastes contaminated either with crude oil or with radionuclides. This presentation describes the use of one such enzyme preparation (Rapidase trademark) for the degradation of cotton sorbents intentionally contaminated with low levels of plutonium. This is part of a feasibility study to determine if such treatments have a role in reducing the volume of low level and transuranic wastes to minimize the amount of radionuclide-contaminated waste that must be disposed of in secured storage areas

Enzymatic degradation of plutonium-contaminated cellulose products

International Nuclear Information System (INIS)

Heintz, C.E.; Rainwater, K.A.; Swift, L.M.; Barnes, D.L.; Worl, L.A.

1999-01-01

Enzyme solutions produced for commercial purposes unrelated to waste management have the potential for reducing the volume of wastes in streams containing cellulose, lipid and protein materials. For example, the authors have shown previously that cellulases used in denim production and in detergent formulations are able to digest cellulose-containing sorbents and other cellulose-based wastes contaminated either with crude oil or with uranium. This presentation describes the use of one such enzyme preparation (Rapidase trademark, manufactured by Genencor, Rochester, NY) for the degradation of cotton sorbents intentionally contaminated with low levels of plutonium. This is part of a feasibility study to determine if such treatments have a role in reducing the volume of low level and transuranic wastes to minimize the amount of radionuclide-contaminated waste destined for costly disposal options

Characterization of degradation products of amorphous and polymorphic forms of clopidogrel bisulphate under solid state stress conditions

DEFF Research Database (Denmark)

Raijada, Dhara K; Prasad, Bhagwat; Paudel, Amrit

2010-01-01

The present study deals with the stress degradation studies on amorphous and polymorphic forms of clopidogrel bisulphate. The objective was to characterize the degradation products and postulate mechanism of decomposition of the drug under solid state stress conditions. For that, amorphous form, ...

Adaptation mechanisms of bacteria during the degradation of polychlorinated biphenyls in the presence of natural and synthetic terpenes as potential degradation inducers

Energy Technology Data Exchange (ETDEWEB)

Zoradova-Murinova, Slavomira; Dudasova, Hana; Lukacova, Lucia; Certik, Milan; Dercova, Katarina [Slovak Univ. of Technology, Bratislava (Slovakia). Inst. of Biotechnology and Food Science; Silharova, Katarina; Vrana, Branislav [Water Research Institute, Bratislava (Slovakia)

2012-06-15

In this study, we examined the effect of polychlorinated biphenyls (PCBs) in the presence of natural and synthetic terpenes and biphenyl on biomass production, lipid accumulation, and membrane adaptation mechanisms of two PCB-degrading bacterial strains Pseudomonas stutzeri and Burkholderia xenovorans LB400. According to the results obtained, it could be concluded that natural terpenes, mainly those contained in ivy leaves and pine needles, decreased adaptation responses induced by PCBs in these strains. The adaptation processes under investigation included growth inhibition, lipid accumulation, composition of fatty acids, cis/trans isomerization, and membrane saturation. Growth inhibition effect decreased upon addition of these natural compounds to the medium. The amount of unsaturated fatty acids that can lead to elevated membrane fluidity increased in both strains after the addition of the two natural terpene sources. The cells adaptation changes were more prominent in the presence of carvone, limonene, and biphenyl than in the presence of natural terpenes, as indicated by growth inhibition, lipid accumulation, and cis/trans isomerization. Addition of biphenyl and carvone simultaneously with PCBs increased the trans/cis ratio of fatty acids in membrane fractions probably as a result of fluidizing effects of PCBs. This stimulation is more pronounced in the presence of PCBs as a sole carbon source. This suggests that PCBs alone have a stronger effect on bacterial membrane adaptation mechanisms than when added together with biphenyl or natural or synthetic terpenes. (orig.)

Membrane recognition and dynamics of the RNA degradosome.

Directory of Open Access Journals (Sweden)

Henrik Strahl

2015-02-01

Full Text Available RNase E, which is the central component of the multienzyme RNA degradosome, serves as a scaffold for interaction with other enzymes involved in mRNA degradation including the DEAD-box RNA helicase RhlB. Epifluorescence microscopy under live cell conditions shows that RNase E and RhlB are membrane associated, but neither protein forms cytoskeletal-like structures as reported earlier by Taghbalout and Rothfield. We show that association of RhlB with the membrane depends on a direct protein interaction with RNase E, which is anchored to the inner cytoplasmic membrane through an MTS (Membrane Targeting Sequence. Molecular dynamics simulations show that the MTS interacts with the phospholipid bilayer by forming a stabilized amphipathic α-helix with the helical axis oriented parallel to the plane of the bilayer and hydrophobic side chains buried deep in the acyl core of the membrane. Based on the molecular dynamics simulations, we propose that the MTS freely diffuses in the membrane by a novel mechanism in which a large number of weak contacts are rapidly broken and reformed. TIRFm (Total Internal Reflection microscopy shows that RNase E in live cells rapidly diffuses over the entire inner membrane forming short-lived foci. Diffusion could be part of a scanning mechanism facilitating substrate recognition and cooperativity. Remarkably, RNase E foci disappear and the rate of RNase E diffusion increases with rifampicin treatment. Control experiments show that the effect of rifampicin is specific to RNase E and that the effect is not a secondary consequence of the shut off of E. coli transcription. We therefore interpret the effect of rifampicin as being due to the depletion of RNA substrates for degradation. We propose a model in which formation of foci and constraints on diffusion arise from the transient clustering of RNase E into cooperative degradation bodies.

Membrane steam reforming of natural gas for hydrogen production by utilization of medium temperature nuclear reactor

International Nuclear Information System (INIS)

Djati Hoesen Salimy

2010-01-01

The assessment of steam reforming process with membrane reactor for hydrogen production by utilizing of medium temperature nuclear reactor has been carried out. Difference with the conventional process of natural gas steam reforming that operates at high temperature (800-1000°C), the process with membrane reactor operates at lower temperature (~500°C). This condition is possible because the use of perm-selective membrane that separate product simultaneously in reactor, drive the optimum conversion at the lower temperature. Besides that, membrane reactor also acts the role of separation unit, so the plant will be more compact. From the point of nuclear heat utilization, the low temperature of process opens the chance of medium temperature nuclear reactor utilization as heat source. Couple the medium temperature nuclear reactor with the process give the advantage from the point of saving fossil fuel that give direct implication of decreasing green house gas emission. (author)

Modification of chitosan membranes with nanosilica particles as polymer electrolyte membranes

Energy Technology Data Exchange (ETDEWEB)

Kusumastuti, Ella, E-mail: ella.kusuma@gmail.com; Siniwi, Widasari Trisna, E-mail: wsiniwi@gmail.com; Mahatmanti, F. Widhi; Jumaeri [Department of Chemistry, Faculty of Mathematics and Natural Sciences, State University of Semarang D6 Building 2" n" d floor, Sekaran Unnes Campus, Gunungpati, Semarang (Indonesia); Atmaja, Lukman; Widiastuti, Nurul [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Tenth November Institute of Technology Keputih ITS Campus, Sukolilo, Surabaya (Indonesia)

2016-04-19

Chitosan has been widely used as polymer matrix for Polymer Electrolyte Membrane (PEM) application replacing Nafion which has shortcomings in terms of high methanol permeability that degrades the performance of fuel cells. Chitosan membranes modification is performed by adding nanosilica to prevent methanol transport through the membrane. Nanosilica is synthesized by sol-gel method and the particle diameter is obtained by analysis using Breunner Emmet Teller (BET) that is 6.59 nm. Nanosilica is mixed with chitosan solution to obtain nanosilica-chitosan as polymer electrolyte membrane. The membranes are synthesized through phase inversion method with nanosilica composition including 0; 0.5; 1; 2; 3; 5; and 10% w/w of chitosan. Characterization of the membranes indicate that the results of water swelling, proton conductivity and methanol permeability of the membrane with 3% nanosilica respectively were 49.23%, 0.231 S/cm, and 5.43 x 10{sup −7} cm{sup 2}/s. Based on the results of membrane selectivity calculation, the optimum membrane is the composition of 3% nanosilica with value 5.91 x 105 S s cm{sup −3}. The results of functional groups analysis with FTIR showed that it was only physical interaction that occurred between chitosan and nanosilica since no significant changes found in peak around the wave number 1000-1250 cm{sup −-1}.

Natural and enhanced anaerobic degradation of 1,1,1-trichloroethane and its degradation products in the subsurface – A critical review

DEFF Research Database (Denmark)

Scheutz, Charlotte; Durant, Neal D.; Hansen, Maria Heisterberg

2011-01-01

1,1,1-Trichloroethane (TCA) in groundwater is susceptible to a variety of natural degradation mechanisms. Evidence of intrinsic decay of TCA in aquifers is commonly observed; however, TCA remains a persistent pollutant at many sites and some of the daughter products that accumulate from intrinsic...

Effectiveness of commercial microbial products in enhancing oil degradation in Prince William Sound field plots

International Nuclear Information System (INIS)

Venosa, A.D.; Haines, J.R.; Allen, D.M.

1991-01-01

In the spring of 1990, previously reported laboratory experiments were conducted on 10 commercial microbial products to test for enhanced biodegradation of weathered crude oil from the Exxon Valdez oil spill. The laboratory tests measured the rate and extent of oil degradation in closed flasks. Weathered oil from the beaches in Alaska and seawater from Prince William Sound were used in the tests. Two of the 10 products were found to provide significantly greater alkane degradation than flasks supplemented with mineral nutrients alone. These two products were selected for further testing on a beach in Prince William Sound. A randomized complete block experiment was designed to compare the effectiveness of these two products in enhancing oil degradation compared to simple fertilizer alone. Four small plots consisting of a no nutrient control, a mineral nutrient plot, and two plots receiving mineral nutrients plus the two products, were laid out on a contaminated beach. These four plots comprised a 'block' of treatments, and this block was replicated four times on the same beach. Triplicate samples of beach sediment were collected at four equally spaced time intervals and analyzed for oil residue weight and alkane hydrocarbon profile changes with time. The objective was to determine if either of the two commercial microbiological products was able to enhance bioremediation of an oil-contaminated beach in Prince William Sound to an extent greater than that achievable by simple fertilizer application. Results indicated no significant differences among the four treatments in the 27-day period of the experiment

Experimental evaluation of methane dry reforming process on a membrane reactor to hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Silva, Fabiano S.A.; Benachour, Mohand; Abreu, Cesar A.M. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. of Chemical Engineering], Email: f.aruda@yahoo.com.br

2010-07-01

In a fixed bed membrane reactor evaluations of methane-carbon dioxide reforming over a Ni/{gamma}- Al{sub 2}O{sub 3} catalyst were performed at 773 K, 823 K and 873 K. A to convert natural gas into syngas a fixed-bed reactor associate with a selective membrane was employed, where the operating procedures allowed to shift the chemical equilibrium of the reaction in the direction of the products of the process. Operations under hydrogen permeation, at 873 K, promoted the increase of methane conversion, circa 83%, and doubled the yield of hydrogen production, when compared with operations where no hydrogen permeation occurred. (author)

Estimation of PMI depends on the changes in ATP and its degradation products.

Science.gov (United States)

Mao, Shiwei; Fu, Gaowen; Seese, Ronald R; Wang, Zhen-Yuan

2013-09-01

Estimating the time since death, or postmortem interval (PMI), has been one of the biggest difficulties in modern forensic investigation. This study tests if the concentrations of breakdown products of adenosine triphosphate (ATP) correlate with PMI in multiple organs from rat. Brains, spleens, and kidneys of rats were harvested at different time points in carcasses maintained at 4°C or 20°C. High Performance Liquid Chromatography (HPLC) was used to quantify concentrations of metabolites related to ATP degradation. A K value (Kv=100×(Hx+HxR)/(ATP+ADP+AMP+IMP+HxR+Hx)) was calculated and correlated with PMI for each organ and temperature. The results indicate that the K value is a robust index for the estimation of PMI based on highly significant linear correlations between PMI and concentrations of ATP breakdown products. Compared with other current research methods, the changing tendency of ATP and its degradation products may be potentially a better way for the estimation of PMI in medico-legal practice. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Degradation pathway of malachite green in a novel dual-tank photoelectrochemical catalytic reactor.

Science.gov (United States)

Diao, Zenghui; Li, Mingyu; Zeng, Fanyin; Song, Lin; Qiu, Rongliang

2013-09-15

A novel dual-tank photoelectrochemical catalytic reactor was designed to investigate the degradation pathway of malachite green. A thermally formed TiO₂/Ti thin film electrode was used as photoanode, graphite was used as cathode, and a saturated calomel electrode was employed as the reference electrode in the reactor. In the reactor, the anode and cathode tanks were connected by a cation exchange membrane. Results showed that the decolorization ratio of malachite green in the anode and cathode was 98.5 and 96.5% after 120 min, respectively. Malachite green in the two anode and cathode tanks was oxidized, achieving the bipolar double effect. Malachite green in both the anode and cathode tanks exhibited similar catalytic degradation pathways. The double bond of the malachite green molecule was attacked by strong oxidative hydroxyl radicals, after which the organic compound was degraded by the two pathways into 4,4-bis(dimethylamino) benzophenone, 4-(dimethylamino) benzophenone, 4-(dimethylamino) phenol, and other intermediate products. Eventually, malachite green was degraded into oxalic acid as a small molecular organic acid, which was degraded by processes such as demethylation, deamination, nitration, substitution, addition, and other reactions. Copyright © 2013 Elsevier B.V. All rights reserved.

End-to-end gene fusions and their impact on the production of multifunctional biomass degrading enzymes

International Nuclear Information System (INIS)

Rizk, Mazen; Antranikian, Garabed; Elleuche, Skander

2012-01-01

Highlights: ► Multifunctional enzymes offer an interesting approach for biomass degradation. ► Size and conformation of separate constructs play a role in the effectiveness of chimeras. ► A connecting linker allows for maximal flexibility and increased thermostability. ► Genes with functional similarities are the best choice for fusion candidates. -- Abstract: The reduction of fossil fuels, coupled with its increase in price, has made the search for alternative energy resources more plausible. One of the topics gaining fast interest is the utilization of lignocellulose, the main component of plants. Its primary constituents, cellulose and hemicellulose, can be degraded by a series of enzymes present in microorganisms, into simple sugars, later used for bioethanol production. Thermophilic bacteria have proven to be an interesting source of enzymes required for hydrolysis since they can withstand high and denaturing temperatures, which are usually required for processes involving biomass degradation. However, the cost associated with the whole enzymatic process is staggering. A solution for cost effective and highly active production is through the construction of multifunctional enzyme complexes harboring the function of more than one enzyme needed for the hydrolysis process. There are various strategies for the degradation of complex biomass ranging from the regulation of the enzymes involved, to cellulosomes, and proteins harboring more than one enzymatic activity. In this review, the construction of multifunctional biomass degrading enzymes through end-to-end gene fusions, and its impact on production and activity by choosing the enzymes and linkers is assessed.

Effects of cellulosic degradation product concentration on actinide sorption on tuffs from the Borrowdale Volcanic Group, Sellafield, Cumbria

International Nuclear Information System (INIS)

Baston, G.M.N.; Berry, J.A.; Bond, K.A.; Boult, K.A.; Linklater, C.M.

1994-01-01

The Nirex Safety Assessment Research Programme includes an investigation into the effects of cellulosic degradation products on the sorption of radioelements onto geological materials. Previous batch sorption studies have shown that the presence of high concentrations of both authentic cellulosic degradation products (produced by alkaline degradation of wood/tissue) and the well-characterised simulant, gluconate, can cause marked reductions in actinide sorption. This work has now been extended to cover a range of concentrations of both authentic cellulosic degradation products and their simulants, gluconate and iso-saccharinate. Geological samples were from the proposed Nirex underground radioactive waste disposal site at Sellafied, Cumbria. The nuclides studied were thorium and plutonium. In the presence of gluconate or iso-saccharinate, at concentrations above 10 -4 M, the present work has confirmed the trends shown by earlier experiments, with a significant reduction in actinide sorption (R D values reduced by less than a factor of two), and in some cases the results suggested a slight increase (R D values increased by up to a factor of four). (orig.)

Effects of cellulosic degradation product concentration on actinide sorption on tuffs from the Borrowdale Volcanic Group, Sellafield, Cumbria

Energy Technology Data Exchange (ETDEWEB)

Baston, G.M.N. [AEA Technology, Decommissioning and Waste Management, Harwell (United Kingdom); Berry, J.A. [AEA Technology, Decommissioning and Waste Management, Harwell (United Kingdom); Bond, K.A. [AEA Technology, Decommissioning and Waste Management, Harwell (United Kingdom); Boult, K.A. [AEA Technology, Decommissioning and Waste Management, Harwell (United Kingdom); Linklater, C.M. [AEA Technology, Decommissioning and Waste Management, Harwell (United Kingdom)

1994-12-31

The Nirex Safety Assessment Research Programme includes an investigation into the effects of cellulosic degradation products on the sorption of radioelements onto geological materials. Previous batch sorption studies have shown that the presence of high concentrations of both authentic cellulosic degradation products (produced by alkaline degradation of wood/tissue) and the well-characterised simulant, gluconate, can cause marked reductions in actinide sorption. This work has now been extended to cover a range of concentrations of both authentic cellulosic degradation products and their simulants, gluconate and iso-saccharinate. Geological samples were from the proposed Nirex underground radioactive waste disposal site at Sellafied, Cumbria. The nuclides studied were thorium and plutonium. In the presence of gluconate or iso-saccharinate, at concentrations above 10{sup -4} M, the present work has confirmed the trends shown by earlier experiments, with a significant reduction in actinide sorption (R{sub D} values reduced by less than a factor of two), and in some cases the results suggested a slight increase (R{sub D} values increased by up to a factor of four). (orig.)

The vascular basement membrane in the healthy and pathological brain.

Science.gov (United States)

Thomsen, Maj S; Routhe, Lisa J; Moos, Torben

2017-10-01

The vascular basement membrane contributes to the integrity of the blood-brain barrier (BBB), which is formed by brain capillary endothelial cells (BCECs). The BCECs receive support from pericytes embedded in the vascular basement membrane and from astrocyte endfeet. The vascular basement membrane forms a three-dimensional protein network predominantly composed of laminin, collagen IV, nidogen, and heparan sulfate proteoglycans that mutually support interactions between BCECs, pericytes, and astrocytes. Major changes in the molecular composition of the vascular basement membrane are observed in acute and chronic neuropathological settings. In the present review, we cover the significance of the vascular basement membrane in the healthy and pathological brain. In stroke, loss of BBB integrity is accompanied by upregulation of proteolytic enzymes and degradation of vascular basement membrane proteins. There is yet no causal relationship between expression or activity of matrix proteases and the degradation of vascular matrix proteins in vivo. In Alzheimer's disease, changes in the vascular basement membrane include accumulation of Aβ, composite changes, and thickening. The physical properties of the vascular basement membrane carry the potential of obstructing drug delivery to the brain, e.g. thickening of the basement membrane can affect drug delivery to the brain, especially the delivery of nanoparticles.

Different Spectrophotometric Methods for Simultaneous Determination of Trelagliptin and Its Acid Degradation Product

Science.gov (United States)

Hassan, Mostafa A.; Zaghary, Wafaa A.

2018-01-01

New spectrophotometric and chemometric methods were carried out for the simultaneous assay of trelagliptin (TRG) and its acid degradation product (TAD) and applied successfully as a stability indicating assay to recently approved Zafatek® tablets. TAD was monitored using TLC to ensure complete degradation. Furthermore, HPLC was used to confirm dealing with one major acid degradation product. The proposed methods were developed by manipulating zero-order, first-derivative, and ratio spectra of TRG and TAD using simultaneous equation, first-derivative, and mean-centering methods, respectively. Using Spectra Manager II and Minitab v.14 software, the absorbance at 274 nm–260.4 nm, amplitudes at 260.4 nm–274.0 nm, and mean-centered values at 287.6 nm–257.2 nm were measured against methanol as a blank for TRG and TAD, respectively. Linearity and the other validation parameters were acceptable at concentration ranges of 5–50 μg/mL and 2.5–25 μg/mL for TRG and TAD, respectively. Using one-way analysis of variance (ANOVA), the optimized methods were compared and proved to be accurate for the simultaneous assay of TRG and TAD. PMID:29629213

In situ ruminal crude protein degradability of by-products from cereals, oilseeds and animal origin

NARCIS (Netherlands)

Habib, G.; Khan, N.A.; Ali, M.; Bezabih, M.

2013-01-01

The aim of this study was to establish a database on in situ ruminal crude protein (CP) degradability characteristics of by-products from cereal grains, oilseeds and animal origin commonly fed to ruminants in Pakistan and South Asian Countries. The oilseed by-products were soybean meal, sunflower

Phospholipase C-catalyzed sphingomyelin hydrolysis in a membrane reactor for ceramide production

DEFF Research Database (Denmark)

Zhang, Long; Liang, Shanshan; Hellgren, Lars

2008-01-01

A membrane reactor for the production of ceramide through sphingomyelin hydrolysis with phospholipase C from Clostridium perfringens was studied for the first time. Ceramide has raised a large interest as an active component in both pharmaceutical and cosmetic industry. The enzymatic hydrolysis...

Degradation signals for ubiquitin system proteolysis in Saccharomyces cerevisiae.

Science.gov (United States)

Gilon, T; Chomsky, O; Kulka, R G

1998-01-01

Combinations of different ubiquitin-conjugating (Ubc) enzymes and other factors constitute subsidiary pathways of the ubiquitin system, each of which ubiquitinates a specific subset of proteins. There is evidence that certain sequence elements or structural motifs of target proteins are degradation signals which mark them for ubiquitination by a particular branch of the ubiquitin system and for subsequent degradation. Our aim was to devise a way of searching systematically for degradation signals and to determine to which ubiquitin system subpathways they direct the proteins. We have constructed two reporter gene libraries based on the lacZ or URA3 genes which, in Saccharomyces cerevisiae, express fusion proteins with a wide variety of C-terminal extensions. From these, we have isolated clones producing unstable fusion proteins which are stabilized in various ubc mutants. Among these are 10 clones whose products are stabilized in ubc6, ubc7 or ubc6ubc7 double mutants. The C-terminal extensions of these clones, which vary in length from 16 to 50 amino acid residues, are presumed to contain degradation signals channeling proteins for degradation via the UBC6 and/or UBC7 subpathways of the ubiquitin system. Some of these C-terminal tails share similar sequence motifs, and a feature common to almost all of these sequences is a highly hydrophobic region such as is usually located inside globular proteins or inserted into membranes. PMID:9582269

Mass spectrometry for the elucidation of the subtle molecular structure of biodegradable polymers and their degradation products.

Science.gov (United States)

Kowalczuk, Marek; Adamus, Grażyna

2016-01-01

Contemporary reports by Polish authors on the application of mass spectrometric methods for the elucidation of the subtle molecular structure of biodegradable polymers and their degradation products will be presented. Special emphasis will be given to natural aliphatic (co)polyesters (PHA) and their synthetic analogues, formed through anionic ring-opening polymerization (ROP) of β-substituted β-lactones. Moreover, the application of MS techniques for the evaluation of the structure of biodegradable polymers obtained in ionic and coordination polymerization of cyclic ethers and esters as well as products of step-growth polymerization, in which bifunctional or multifunctional monomers react to form oligomers and eventually long chain polymers, will be discussed. Furthermore, the application of modern MS techniques for the assessment of polymer degradation products, frequently bearing characteristic end groups that can be revealed and differentiated by MS, will be discussed within the context of specific degradation pathways. Finally, recent Polish accomplishments in the area of mass spectrometry will be outlined. © 2015 Wiley Periodicals, Inc.

Biosurfactant production by Pseudomonas fluorescens growing on molasses and its application in phenol degradation

Science.gov (United States)

Suryantia, Venty; Marliyana, Soerya Dewi; Wulandari, Astri

2015-12-01

A molasses based medium for the biosurfactant production by Pseudomonas fluorescens was developed, where the effect of pre-treated of molasses and medium composition were evaluated. Biosurfactant production was followed by measuring optical density (OD), surface tension and emulsifying index (E24) over 12 days of fermentation. The optimum condition for the biosurfactant production was obtained when a medium containing of 8 g/L nutrient broth, 5 g/L NaCl, 1 g/L NH4NO3 and 5% v/v pre-treated molasses with centrifugation was used as media with 3 days of fermentation. The biosurfactant was identified as a rhamnolipid type biosurfactant which had critical micelle concentration (CMC) value of 801 mg/L and was able to reduce the surface tension of the water from 80 mN/m to 51 mN/m. The biosurfactants had water in oil (w/o) emulsion type. Biosurfactant was able to emulsify various hydrocarbons, which were able to decrase the interfacial tension about 50-75% when benzyl chloride, anisaldehyde and palm oil were used as immiscible compounds. The biosurfactant exhibited the E24 value of about 50% and the stable emulsion was reached up to 30 days when lubricant was used as an immiscible compound. Up to 68% of phenol was degraded in the presence of biosurfactant within 15 days, whereas only 56% of phenol was degraded in the absence of biosurfactant. Overall, the results exhibited that molasses are recommended for the rhamnolipids production which possessed good surface-active properties and had potential application in the enhancement of phenol degradation.

Ion-conducting membranes

Science.gov (United States)

Masel, Richard I.; Sajjad, Syed Dawar; Gao, Yan; Liu, Zengcai; Chen, Qingmei

2017-12-26

An anion-conducting polymeric membrane comprises a terpolymer of styrene, vinylbenzyl-R.sub.s and vinylbenzyl-R.sub.x. R.sub.s is a positively charged cyclic amine group. R.sub.x is at least one constituent selected from the group consisting Cl, OH and a reaction product between an OH or Cl and a species other than a simple amine or a cyclic amine. The total weight of the vinylbenzyl-R.sub.x groups is greater than 0.3% of the total weight of the membrane. In a preferred embodiment, the membrane is a Helper Membrane that increases the faradaic efficiency of an electrochemical cell into which the membrane is incorporated, and also allows product formation at lower voltages than in cells without the Helper Membrane.

Continuous production of polymethylpentene membranes

Science.gov (United States)

Epperson, B.J.; Burnett, L.J.; Helm, V.D.

1983-11-15

Gas separation membranes may be prepared in a continuous manner by passing a porous support which may, if so desired, be backed by a fabric through a solution of polymethylpentene dissolved in an organic solvent such as hexane. The support member is passed through the solution while one side thereof is in contact with a roller, thereby permitting only one side of the support member to be coated with the polymer. After continuously withdrawing the support member from the bath, the solvent is allowed to evaporate and the resulting membrane is recovered.

Investigation of relationships between removals of tetracycline and degradation products and physicochemical parameters in municipal wastewater treatment plant.

Science.gov (United States)

Topal, Murat; Uslu Şenel, Gülşad; Öbek, Erdal; Arslan Topal, E Işıl

2016-05-15

Determination of the effect of physicochemical parameters on the removal of tetracycline (TC) and degradation products is important because of the importance of the removal of antibiotics in Wastewater Treatment Plant (WWTP). Therefore, the purpose of this study was to investigate the relationships between removals of TC and degradation products and physicochemical parameters in Municipal Wastewater Treatment Plant (MWWTP). For this aim, (i) the removals of physicochemical parameters in a MWWTP located in Elazığ city (Turkey) were determined (ii) the removals of TC and degradation products in MWWTP were determined (iii) the relationships between removals of TC and degradation products and physicochemical parameters were investigated. TC, 4-epitetracycline (ETC), 4-epianhydrotetracycline (EATC), anhydrotetracycline (ATC), and physicochemical parameters (pH, temperature, electrical conductivity (EC), suspended solids (SS), BOD5, COD, total organic carbon (TOC), NH4(+)-N, NO2(-)-N, NO3(-)-N and O-PO4(-3)) were determined. The calculation of the correlation coefficients of relationships between the physicochemical parameters and TC, EATC, ATC showed that, among the investigated parameters, EATC and SS most correlated. The removals of other physicochemical parameters were not correlated with TC, EATC and ATC. Copyright © 2016 Elsevier Ltd. All rights reserved.

Generation of toxic degradation products by sonication of Pluronic® dispersants: implications for nanotoxicity testing.

Science.gov (United States)

Wang, Ruhung; Hughes, Tyler; Beck, Simon; Vakil, Samee; Li, Synyoung; Pantano, Paul; Draper, Rockford K

2013-11-01

Poloxamers (known by the trade name Pluronic®) are triblock copolymer surfactants that contain two polyethylene glycol blocks and one polypropylene glycol block of various sizes. Poloxamers are widely used as nanoparticle dispersants for nanotoxicity studies wherein nanoparticles are sonicated with a dispersant to prepare suspensions. It is known that poloxamers can be degraded during sonication and that reactive oxygen species contribute to the degradation process. However, the possibility that poloxamer degradation products are toxic to mammalian cells has not been well studied. We report here that aqueous solutions of poloxamer 188 (Pluronic® F-68) and poloxamer 407 (Pluronic® F-127) sonicated in the presence or absence of multi-walled carbon nanotubes (MWNTs) can became highly toxic to cultured cells. Moreover, toxicity correlated with the sonolytic degradation of the polymers. These findings suggest that caution should be used in interpreting the results of nanotoxicity studies where the potential sonolytic degradation of dispersants was not controlled.

Studies on the Conditioning Methods of Spent Tri-butyl Phosphate/Kerosene and its Degradation Product in Different Matrices

International Nuclear Information System (INIS)

El-Dessouky, M.I.; El-sourougy, M.R.; Abed El-Aziz, M.M.; Aly, H.F.

1999-01-01

The destruction of spent TBP/Kerosene (odourless Kerosene (OK)) with potassium permanganate have been investigated. Comparative studies on the immobilization of spent TBP/Kerosene and its degradation product into different matrices have been carried out. The matrices used include, ordinary Portland cement, silica fume, treated fly ash, epoxy resin and cement mixed with epoxy resin.The different factors affecting solidified waste forms such as, compressive strength, water resistance, thermal stability, chemical resistance, radiological stability and leachability have been investigated. It was found that, epoxy resin and cement mixed with 5,10,20, and 50% of epoxy resin enhance the compressive strength of the solidified waste forms with spent TBP/OK more than that obtained from degradation products. The leaching rates of 152 and 154 Eu and 181 Hf from waste forms containing TBP/OK was found lower than that with degradation product

Application of CO{sub 2} selective membrane reactors in pre-combustion decarbonisation systems for power production

Energy Technology Data Exchange (ETDEWEB)

Steven C.A. Kluiters; Virginie C. Feuillade; Jan Wilco Dijkstra; Daniel Jansen; Wim G. Haije [Energy research Centre of the Netherlands (ECN), Petten (Netherlands)

2006-07-01

For pre-combustion decarbonisation of fuels for large-scale power production or H{sub 2} generation both CO{sub 2} and H{sub 2} selective membranes are viable candidates for use in steam reforming and water gas shift membrane reactors. It will be shown that the choice between either option is not a matter of taste, but dictated by the fuel used and, to a lesser extent, the total system layout. Hydrotalcites, clay-like materials, are shown to be promising candidates as membrane material for low temperature, below 400{sup o}C, membrane shift reactors. 7 refs., 6 figs., 1 tab.

Analysis of Gas Separated for Silica Membrane in Hydrogen Gas Production by Using Nuclear Reactor Thermal

International Nuclear Information System (INIS)

Pandiangan, Tumpal

2007-01-01

One of the hydrogen production method that have been developed is a thermo-chemical method. This method is permissible to increase thermal efficiency up to 70 % and to decrease of operational temperature from 800℃ down to 450 ℃. One of several factor that can increase of the hydrogen production thermal efficiency at the above method is to apply a separated membrane that have a relative good for permeansce and selectivity performance. It had been carried out for analyzing of time and temperature CVD (Chemical Vapouration Deposition) that is affected to permeansce and power selecting performance of the membrane. The layering membrane silica process was carried out by means of the CVD method at atmosphere pressure. The membrane silica layering that was observed was developed by a CVD method in atmospheric pressure. The silica membrane was formed at the out side surface of the alumina gamma cylinder that had been coated by alumina gamma which it has average porosity about of 0.01 mic.meter. A permeansce and separation power performance of the membrane silica that was carried out by means of CVD method at 600 ℃ on H 2 , He and N 2 are : 2 x 10 -10 , 9 x 10 -9 and 4 x 10 -7 mol Pa/m 2 s and the selected power of H 2 /N 2 = 45. The permeansce of that membrane is relative good but the selected power is relative not so good. (author)

Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass

DEFF Research Database (Denmark)

Klinke, H.B.; Thomsen, A.B.; Ahring, Birgitte Kiær

2004-01-01

for ethanol fermentation. The resulting hydrolyzsates contain substances inhibitory to fermentation-depending on both the raw material (biomass) and the pre-treatment applied. An overview of the inhibitory effect on ethanol production by yeast and bacteria is presented. Apart from furans formed by sugar......An overview of the different inhibitors formed by pre-treatment of lignocellulosic materials and their inhibition of ethanol production in yeast and bacteria is given. Different high temperature physical pre-treatment methods are available to render the carbohydrates in lignocellulose accessible...... degradation, phenol monomers from lignin degradation are important co-factors in hydrolysate inhibition, and inhibitory effects of these aromatic compounds on different ethanol producing microorganisms is reviewed. The furans and phenols generally inhibited growth and ethanol production rate (Q...

Complexation of Cu2+, Ni2+ and UO22+ by radiolytic degradation products of bitumen

International Nuclear Information System (INIS)

Loon, L.R. Van; Kopajtic, Z.

1990-05-01

The radiolytic degradation of bitumen was studied under conditions which reflect those which will exist in the near field of a cementitious radioactive waste repository. The potential complexation capacity of the degradation products was studied and complexation experiments with Cu 2+ , Ni 2+ and UO 2 2+ were performed. In general 1:1 complexes with Cu 2+ , Ni 2+ and UO 2 2+ , with log K values of between 5.7 and 6.0 for Cu 2+ , 4.2 for Ni 2+ and 6.1 for UO 2 2+ , were produced at an ionic strength of 0.1 M. The composition of the bitumen water was analysed by GC-MS and IC. The major proportion of the bitumen degradation products in solution were monocarboxylic acids (acetic acid, formic acid, myric acid, stearic acid ...), dicarboxylic acids (oxalic acid, phthalic acid) and carbonates. The experimentally derived log K data are in good agreement with the literature and suggest that oxalate determines the speciation of Cu 2+ , Ni 2+ and UO 2 2+ in the bitumen water below pH=7. However, under the high pH conditions typical of the near field of a cementitious repository, competition with OH-ligands will be large and oxalate, therefore, will not play a significant role in the speciation of radionuclides. The main conclusion of the study is that the radiolytic degradation products of bitumen will have no influence on radionuclide speciation in a cementitious near field and, as such, need not to be considered in the appropriate safety assessment models. (author) 12 figs., 11 tabs., 31 refs

Biological activity of anthocyanins and their phenolic degradation products and metabolites in human vascular endothelial cells

OpenAIRE

Edwards, Michael

2013-01-01

Human, animal, and in vitro data indicate significant vasoprotective activity of anthocyanins. However, few studies have investigated the activity of anthocyanin degradation products and metabolites which are likely to mediate bioactivity in vivo. The present thesis therefore examined the vascular bioactivity in vitro of anthocyanins, their phenolic degradants, and the potential for interactions between dietary bioactive compounds. Seven treatment compounds (cyanidin-, peonidin-, petunidin- &...

Hydrogenation of Maltose in Catalytic Membrane Reactor for Maltitol Production